WO2008098245A2 - Nmda receptor modulation and treatments for addictive behavior - Google Patents

Abstract

The instant disclosure relates generally to methods for treating an individual with a psychiatric disorder with a pharmacologic agent that enhances learning or conditioning in combination with psychotherapy. In one aspect, the disclosure provides a method of treating addictive disorder comprising administering to a subject in need thereof a pharmaceutically effective amount of a NMDA receptor modulatory agent prior to, concurrent with, or following extinction training whereby the reinstatement of drug seeking behavior is reduced.

Description

NMDA RECEPTOR MODULATION AND TREATMENTS FOR ADDICTIVE

BEHAVIOR

RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application Serial No. 60/888, 959, filed February 9th, 2007, the content of which is incorporated by reference in its entirety.

U.S. GOVERNMENT RIGHTS

[0002] This invention was supported in part by United States Government Grant No. DAO 16302 awarded by National Institutes of Health. The United States Government may have certain rights in the invention.

FIELD

[0003] The instant disclosure relates generally to methods for treating an individual with a psychiatric disorder with a pharmacologic agent that enhances learning or conditioning in combination with psychotherapy. In one aspect, the instant disclosure is directed to the modulation of the NMDA receptor in extinction training and the reduction of the reinstatement of drug seeking behavior.

BACKGROUND

[0004] The following includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art, or relevant, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.

[0005] In rodent models for relapse of drug seeking behavior in humans, exposure to various modes of priming stimuli (e.g. environmental context, conditioned cues, addictive drugs, stressors) following either extinction or abstinence can evoke, or reinstate, instrumental behaviors previously associated with the self-administration of an addictive substance (Shaham Y, et al., Psychopharmacology (Berl), 2003; 168: 3-20). An extinction training phase is typically incorporated into such protocols, in order to reduce instrumental responding to a low, stable baseline level from which the effectiveness of primed reinstatement can be assessed, although reinstatement can also be assessed following periods of prolonged abstinence (Shalev U, et al., Pharmacol Rev, 2002; 54: 1-42). Much effort has been directed toward determining the neural substrates involved in the mechanisms of priming itself induced by various stimuli (See RE. Eur J Pharmacol, 2005; 526; 140-146), however, little information is available concerning the mechanisms underlying the effectiveness of an extinction training experience to reduce instrumental responding following a priming event.

[0006] Using other behavioral models, evidence indicates that new learning is occurring during the extinction training experience (Bouton ME, et al., Biol Psychiat, 2006; 60: 352-60). This new learning may be dependent upon the activation of n-methyl-d-aspartate receptors (NMDARs). For example, conditioned fear has been used to demonstrate that NMDAR antagonists administered prior to extinction sessions can significantly inhibit extinction (Baker JD, Azorlosa JL. Behav Neurosci, 1996;110: 618-620), and recent reports have indicated that treatment with D-cycloserine (an NMDAR coagonist) can facilitate extinction of conditioned fear (Ledgerwood L, et al., Behav Neurosci, 2003; 117: 341-349; Walker DL, et al., J Neurosci, 2002;22: 2343-2351). Together, these findings indicate an involvement of NMDARs in the learning process that occurs during an extinction training experience.

[0007] Grimm & See reported that inactivation of the NAc was effective in preventing drug (cocaine) induced drug seeking, but had no effect on CS induced priming of reinstatement (Grimm JW, See RE. Neuropsychopharmacology, 2000; 22: 473-479). The opposite relationship was found to exist for BLA inactivation, as TTX infusion into the BLA did not affect drug-primed reinstatement. These studies established a basis for multiple, discrete neuronal mechanisms in mediating the primed reinstatement of drug-seeking behavior.

[0008] U.S. published patent applications US20040208923, US20050096396, and US20060252761 to Davis et al report the use of pharmacologic augmentation of psychotherapy in the treatment of phobia or post traumatic stress syndrome (PTSD). However, there is very little neurophysiological evidence indicating the extinction of fear conditioning and the extinction of drug seeking share the same mechanism. Thus, there is an unmet need for definitive novel methods and/or compositions for pharmacologic augmentation of psychotherapy in the treatment of addiction.

[0009] The instant disclosure is based on the surprising discovery that pharmacologic augmentation of psychotherapy has an unexpected utility in the treatment of addiction.

SUMMARY OF THE INVENTION

[0010] The inventions described and claimed herein have many attributes and embodiments including, but not limited to, those set forth or described or referenced in this Brief Summary. It is not intended to be all-inclusive and the inventions described and claimed herein are not limited to or by the features or embodiments identified in this Brief Summary, which is included for purposes of illustration only and not restriction.

[0011] Accordingly, aspects of the instant disclosure are directed to the use of glycine modulators (e.g. agonists) at the NMDA receptor as adjunctive pharmacotherapy with behavioral modification therapy for the treatment of addiction. Aspects include methods of treating addiction comprising the use of such agents in conjunction with behavioral therapy to enhance the effectiveness of said therapy.

BRIEF DESCRIPTION OF THE FIGURES

[0012] Figure 1. Self-administration of cocaine is stable prior to extinction training.

The results from one cocaine group of rats (open boxes, n=22) illustrate the average number cocaine infusions earned daily during each 90 minute session during the SA phase (days 1-15). Transition to the FR3 schedule on day 13 did not significantly alter the number of earned infusions. During the extinction phase (days 16-20), no infusions were delivered (the active lever had no programmed consequences), but the number of earned infusions was counted. A saline control group of rats (filled triangles, n=10) is illustrated for comparison.

[0013] Figure 2. Extinction behavior between and within sessions. A) Active and inactive lever presses of a cocaine extinguished group (n=22) are illustrated (mean ± SEM) for the 90 minute sessions on the last day of SA (day 15) and on each day of extinction (days 16-20). In the absence of both CS and US the animals extinguished their drug seeking behavior over a period of 5 days. Active lever presses on extinction days 2-5 were significantly decreased (** p<.001, RM Anova, Bonferroni) from those measured on last day of SA and first day of extinction, (i.e. protocol days 17-20 vs 15 & 16). B) Extinction behavior within a session on the fifth day of extinction (protocol day 20) is illustrated using 10 minute bins. Data are the mean ± SEM of lever presses throughout the 90 minute extinction session.

[0014] Figure 3. Extinction training reduces the response to the contextual drug stimuli. Data show the mean ± SEM of active lever presses for the first 10 minute bin of time on the first extinction day (protocol day 16) and the first reinstatement test day (day 21) when the animals were placed back into the operant environment after either 5 days of extinction training or 5 days of enforced abstinence. Drug seeking behavior on day 21 in response to the contextual drug stimuli was significantly decreased in the extinguished group (n=22, ** p< .01, unpaired t- test) as compared to that observed in the abstinent group (n=15).

[0015] Figure 4. Noncontingent CS prime evoked drug seeking behavior. A) Data show the mean ± SEM of active and inactive lever presses in 10 minute bins for 30-70 minutes of the CS prime test session on the first reinstatement test day (day 21) for the extinguished (n=22) and the abstinent groups (n=14). Lever pressing responses during the '"pre priming" period (30-40 min) were minimal. The delivery of a single noncontingent CS prime (light and tone) at time=40 minutes reinstated the response specifically on the active lever, whereas inactive lever responses remained low throughout the session. B) Data represent the mean ± SEM of the active lever presses for 10 minutes pre prime (30-40 minute bin) and for 10 minutes post prime (40-50 minute bin) for both the extinguished (n=22) and the abstinent groups (n=15). Post prime responses on the active lever were significantly higher for both groups when compared to the pre prime responses (* p<.05, ** p<.01, paired t-test). In addition, the abstinent group showed significantly higher responding to the single noncontingent CS prime as compared to the extinguished group (p<.05, unpaired t-test).

[0016] Figure 5. Extinction training significantly reduces US primed reinstatement.

Data represent the mean ± SEM of the active lever presses for a 30 minute window after the single noncontingent intravenous delivery of a drug prime at the doses indicated (0.5x: 0.25mg/kg, Ix: 0.5mg/kg, 2x: lmg/kg) administered at time=40 minutes on each reinstatement test day (protocol days 22-24). For both extinguished and abstinent groups, the post prime response was significantly greater than the pre prime response at all of the cocaine doses tested (data not shown) and the drug seeking responses of the abstinent animals (n=14 for Ix and n=l 1 for 2x) were significantly higher than those of the extinguished animals (n=21 for Ix and 2x) at priming doses of Ix and 2x (* p<.05, unpaired t-test).

[0017] Figure 6. Influence of NMDAR activity on the progression of extinction.

Data shows the mean ± SEM of active lever presses for the entire 90 minute extinction sessions on protocol days 16-20. The saline treated control group data is replotted from Fig. 2A for comparison. Active lever pressing behavior was extinguished across the 5 daily extinction sessions and responding on extinction days 2-5 was significantly decreased (p<.001, RM Anova, Bonferroni test) from that measured on the first day of extinction (i.e. protocol days 17-20 vs. 16) within each treatment group. A trend was evident in the D-serine treated group (n=15) for an enhancing effect on the rate of extinction as compared to the animals treated with (±)CPP (n=17) or saline, and the drug seeking responses of the D-serine group were significantly lower (* p<.05, Anova/Bonferroni) on the third day of extinction (protocol day 18).

[0018] Figure 7. Altering NMDAR activity during extinction had no effect on reinstatement to the contextual cues or the CS prime, but did affect the response to US prime. The saline group data depicted in panels A-C was previously designated as the "extinguished group" in Figs. 3-5 and is replotted here for comparison. A) Data show the mean ± SEM of active lever presses for the first 10 minute bin of time on the first reinstatement test day (protocol day 21). Neither D-serine (100 mg/kg i.p., n=15) nor (±) CPP (5 mg/kg i.p., n=17) treatment during extinction training had a significant effect on responding as compared with the saline treated controls. B) Data represent the mean ± SEM of the active lever presses for 10 minutes pre prime (30-40 minute bin) and for 10 minutes post prime (40-50 minute bin) for all three extinguished groups. Post prime responses on the active lever were significantly higher for all groups when compared to their pre prime response (* p<.05, ** p<.01 , paired t-test). C) Data represent the mean ± SEM of the active lever presses for a 30 minute bin of time after the single noncontingent intravenous delivery of a drug prime at the doses indicated (0.5x; 0.25mg/kg, Ix; 0.5mg/kg, 2x: 1 mg/kg) administered at time=40 minutes on each reinstatement test day (protocol days 22-24). For all extinguished groups, the post prime response was significantly greater than the pre prime response measured during a 30 minute period of time immediately prior to the drug prime at all of the cocaine doses tested (data not shown). The drug seeking responses of the (±)CPP treatment group (n=13) were significantly higher than those of both the saline treated animals and the D-serine treated animals (n=12) at the Ix priming dose (* p<.05, unpaired t-test)

[0019] Figure 8 shows data confirming that treatment with D-serine can significantly enhance the effectiveness of a sub-optimal extinction training experience (See Example 3).

[0020] Figure 9 shows drug prime reinstatement data obtained from rats that were allowed to self-administer cocaine for 6hrs/day or "long access conditions" instead of 90min/day or "short access" conditions.

DETAILED DESCRIPTIONS

[0021] Accordingly, aspects of the present disclosure are directed to methods for treating addictive behavior in a subject comprising administering a NMDA receptor modulatory agents to said subject in combination with extinction training, wherein the NMDA receptor modulatory agent is administrated prior to, during or following extinction training.

[0022] In particular, aspects of the instant disclosure are directed to the use of glycine agonists at the NMDA receptor as agents for adjunctive pharmacotherapy in combination with behavioral modification therapy for the treatment of addiction disorders. Aspects include the use of such agents in the treatment for addictive behaviors, and that they be used in conjunction with behavioral therapy to enhance the effectiveness of said therapy.

[0023] In one aspect, the disclosure provides a method of treating addictive disorder comprising administering to a subject in need thereof a pharmaceutically effective amount of a NMDA receptor modulatory agent prior to, concurrent with, or following extinction training whereby the reinstatement of drug seeking behavior is reduced. [0024] General Methodology

[0025] The present disclosure is directed to methods for treating an individual with a psychiatric disorder, including, for example, an additive disorder. The methods comprise subjecting the individual to one or more sessions of an adjuvant / combination therapy protocol, where the combination therapy protocol comprises an administration of a therapeutically effective amount of a pharmacologic agent that enhances learning or conditioning in combination with a session of psychotherapy.

[0026] Methods for treating a psychiatric disorder in an individual are provided. The methods comprise subjecting the individual in need of treatment to at least one session of a combination therapy protocol, wherein said protocol comprises administering a therapeutically effective amount of a pharmacologic agent that enhances learning or conditioning within about a suitable prescribed time frame (e.g. 24, 48, 72 or more hours) prior to conducting a session of psychotherapy.

[0027] In certain aspects, the methods comprise blocking the NMDARs with administration of an effective amount of an antagonists or facilitating NMDAR activity with the administration of an effective amount of a coagonists to affect the ability of an extinction training experience to alter the response to primed reinstatement.

[0028] In one aspect, the efficacy of therapy used for the treatment of addictive behavior is enhanced by the adjuvant administration of NMDA receptor modulating compounds such as, for example, D-serine, D-cycloserine, and/or sarcosine. In certain embodiments, the number of such treatment sessions required for a clinical outcome is reduced by such adjuvant pharmacotherapy.

[0029] In another aspect, the method comprises combining coagonist therapy (D-serine, D-cycloserine, glycine) with an inhibitor of glycine uptake in the brain whereby the synergistic/potentiation interaction allows for lower doses of the coagonist to be administered, thus avoiding toxicity/side effects. Suitable exemplary glycine uptake inhibitors are well known in the art and are commercially available from Pfizer, Akzo Nobel, and/or Telik, Inc. [0030] In certain other aspects, methods for decreasing the likelihood of relapse following an extinction experience are provided. In some aspects, the method decreases reinstatement by delaying the onset of reinstatement to a later time point (days/weeks later).

[0031] In certain other aspects, exemplary suitable agents that enhance learning or conditioning can include pharmacologic agents that increase the level of norepinephrine in the brain, pharmacologic agents that increase the level of acetylcholine in the brain and pharmacologic agents that enhance NMDA receptor transmission in the brain. The methods find use in the treatment of a variety of psychiatric disorders, including addictive disorders.

[0032] Definitions

[0033] As used herein, "subject" may include any mammals, including humans, domestic and farm animals, and zoo, sports, or pet animals, such as dogs, horses, cats, sheep, pigs, cows, etc. The preferred mammal herein is a human, including adults, children, and the elderly.

[0034] As used herein, "preventing" means preventing in whole or in part, or ameliorating or controlling.

[0035] As used herein, the term "treating" or "treatment" or "alleviation" refers to both therapeutic treatment and prophylactic or preventative measures and "wherein the object is to prevent or slow down (lessen) the targeted pathologic condition or disorder. The terms "treatment" and "treating" include the amelioration, cessation, or otherwise beneficial alteration of a specified disease, disorder, and/or associated condition or symptoms. Treatment also encompasses prophylaxis. For example, the present invention is useful for preventing relapse in subjects who have previously been cured of the condition.

[0036] As used herein, a "therapeutically effective amount" or "effective amount" in reference to the compositions of the instant disclosure refers to the amount when administered in accordance to the combination therapy protocol of the invention, results in an improved therapeutic benefit relative to that observed with psychotherapy in the absence of administering the pharmacologic agent. For example, where the pharmacologic agent is an agent that enhances NMDA receptor activation or transmission in the brain, a therapeutically effective dose or amount is that amount of the pharmacologic agent that enhances NMDA receptor activation or transmission in the brain relative to the level of NMDA receptor activation or transmission in the brain in the absence of administration of the pharmacologic agent.

[0037] As used herein, the term "medicament" or "drug" is intended to encompass all types of pharmaceutical compounds and includes agents suitable for treating a targeted condition in a subject, e.g., a targeted condition of the brain, and capable of being delivered in active form, in vivo usin ¹gB the methods of the invention.

[0038] As used herein, "psychiatric disorder" refers to a disorder that can be treated with the methods of the present disclosure. Thus an individual may have a single disorder, or may have a constellation of disorders that are to be treated by the methods described herein. Exemplary psychiatric disorders contemplated in the present invention include, but are not limited to addictive disorders, including substance-abuse disorders. The disorders contemplated herein are defined in, for example, the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders (4th ed., American Psychiatric Association, Washington D. C, 1994)), which is herein incorporated by reference.

[0039] As used herein, "reinstatement" may include, or be characterized in whole or in part by, the recovery of a learned response (e.g., lever-pressing behavior) that occurs when a subject is exposed noncontingently to the unconditioned stimulus (e.g., food) after extinction. For example, in studies of reinstatement of drug seeking, reinstatement typically refers to the resumption of drug seeking after extinction following exposure to drugs, drug cues, or stressors. Reinstatement may include "within-session reinstatement procedure" in which drug self- administration training, extinction training, and tests for reinstatement are conducted on the same day; "between-session reinstatement procedure" in which drug self-administration training, extinction training, and tests for reinstatement of drug seeking are conducted on separate daily sessions; or "between-within session reinstatement procedure" in which drug self-administration training is conducted over days, and then extinction training and tests for reinstatement of drug seeking are examined on the same day following different periods of drug withdrawal. [0040] As used herein, "cross-reinstatement" may include reinstatement of drug seeking, following extinction of the drug -reinforced behavior by drugs that are different from the self- administered drug.

[0041] In general, extinction refers to discontinuing the reinforcement (e.g., food, drug) of a response (e.g., lever press). In the terminology of classical conditioning, extinction refers to the presentation of a conditioned stimulus(i), previously paired with a given unconditioned stimulus (e.g., food, drug), in the absence of the primary reinforcer. In studies of cue- induced reinstatement, extinction may refer to lever pressing in the absence of both the drug and the conditioned cues that had previously been paired with drug injections. As used herein, "extinction training" refers to a method wherein a subject having deleterious responses to a given stimulus, is exposed to the stimulus such that the conditions of the exposure are manipulated to control the outcome or otherwise reduce the likelihood of an event occurring that would tend to reinforce the response. The goal of extinction training is to pair the previously aversive stimulus with a new learning resulting from a non-deleterious outcome resulting from the stimulus, thereby generating, in future exposures to the stimulus, a more appropriate response in place of the previous deleterious response.

[0042] As used hererin, exemplary "CPP procedure" can include classical conditioning procedure used to study the conditioned reinforcing effects of drugs or nondrug reinforcers. For example, during training, one portion of a test chamber is associated with injections of a drug and another portion is associated with injections of a vehicle. During testing for CPP, conducted in a drug-free state, the subject is allowed to choose between the drug-paired and the vehicle- paired environment. An increase in preference for the drug-paired context serves as a measure of the conditioned reinforcing effects of the drug.

[0043] As used herein, "contextual drug cue" can include a diffuse set of "background" stimuli (e.g., operant chamber fan, time of day) in the drug self-administration context that becomes associated with the availability and the effects of the drug following repeated daily training sessions. [0044] As used herein, "discrete conditioned drug cue" may include any neutral stimulus (e.g., cue light, tone, sound of infusion pump) that becomes a conditioned reinforcer following repeated pairing with drug infusions and effects during self-administration training.

[0045] As used herein, "discriminative drug cue" can include an environmental stimulus that after discrimination training sets the occasion for drug self-administration behavior (rendering the behavior more likely). During training, this stimulus termed the S (or SD) is presented just before the drug becomes available or throughout the period of self-administration; a different stimulus, termed the S (or S), is presented when the drug is not available either on alternate days or sessions.

[0046] As used herein, "drug self-administration procedure" may include procedures in which laboratory animals typically lever press for drug injections. The premise of this procedure is that psychoactive drugs control behavior by functioning as positive reinforcers. A high concordance exists between drugs self-administered by laboratory animals and those abused by humans.

[0047] As used herein, the term "NMDA receptor" or "NMDA channel" refers to the glutamate receptor channel NMDA subtype (Yamakura and Shimoji (1999) Prog. Neurobiol. 59(3):279-298). The term "agonist" can include any compound that increases the flow of cations through an ionotrophic receptor such as the NMDA receptor, i.e., a channel opener, and which has not been observed to decrease the flow of cations through the same receptor.

[0048] As used herein, NMDA modulatory agents can include, for example, NMDA receptor modulatory agents, including, for example, NMDA receptor agonist and/or NMDA receptor glycine site co-agonist. Exemplary NMDA receptor agonist can include D-serine, glycine, sarcosine and/or D-cycloserine.

[0049] As used herein, the term "antagonist" can includes any compound that reduces the flow of cations through an ionotropic receptor such as the NMDA receptor, i.e., a channel closer, and which has not been observed to increase the flow of cations through the same receptor. [0050] The term "partial agonist" can include a compound that regulates an allosteric site on an ionotropic receptor, such as the NMDA receptor, to increase or decrease the flux of cations through the ligand-gated channel depending on the presence or absence of the principal site ligand, that is, in the presence or absence of a known endogenous ligand binding to a site on the receptor. In the absence of the principal site ligand, a partial agonist increases the flow of cations through the ligand-gated channel, but at a lower flux than achieved by the principal site ligand. A partial agonist partially opens the receptor channel. In the presence of the principal site ligand, a partial agonist decreases the flow of cations through the ligand-gated channel below the flux normally achieved by the principal site ligand.

[0051] As used herein, "glycine agonist" can include pharmacologic agents that enhance N-methyl-D-aspartate (NMDA) receptor activation or transmission (cation flow) in the brain without adverse consequences such as neurotoxic effects. Such enhanced NMDA receptor transmission can be measured by a variety of methods known to the skilled artisan. For example, Luteinizing Hormone (LH) secretion is used as a measure of NMDA receptor activation (see van Berckel et al. (1997) Neuropsychopharm. 16(5):317-324). Other methods include electrophysiological and chemical methods (see Mothet et al. (2000) Proc. Natl. Acad. Sci. USA 97(9):4926-4931). Neurotoxicity can be measured by, for example, the cultured cerebellar granule neuron system described in Boje et al. (1993) Brain Res. 603(2):207-214.

[0052] As used herein, "NMDA receptor agonist," "NMDA receptor antagonist," and "NMDA receptor partial agonist," may be alternately referred to as "NMDA agonist," "NMDA antagonist, " and "NMDA partial antagonist," respectively. Also, "NMDA receptor partial agonist" is intended to be interchangeable with "partial NMDA receptor agonist." The present invention contemplates a variety of molecules acting as such partial NMDA receptor agonists. Examples of such pharmacologic agents include, but are not limited to, compounds that act at the glycine modulatory site of the NMDA receptor (see Yamakura and Shimoji (1999) Prog. Neurobiol. 59(3) :279-298), including, for example, D-cycloserine (DCS), D-serine, and 1- aminocyclopropane-carboxylic acid (ACPC), and sarcosine. Other pharmacologic agents that act as partial NMDA agonists, including polyamines such as spermine and spermidine, are also suitable for use as described herein (Yamakura and Shimoji (1999) Prog. Neurobiol. 59(3):279- 298). Exemplary agonists include D-serine, a full agonist at the glycine modulatory site on the NMDAR, whereas D-cycloserine is a partial agonist.

[0053] As used herein, exemplary agents (including therapeutic agents) suitable for combination, co-administration, and/or co-formulation therapy can include, for example, memory/cognitive enhancers, such as, for example, ampakines (e.g. CX516) and/or other cognitive enhancers that act via the AMPA class of glutamate receptor to enhance learning; calcium channel agonists, including activators of the L-type calcium channels, such as, for example, Bay K 8644, (methyl- l,4-dihydro-2,6-dimethyl-3-nitro-4-(2- trifluoromethylphenyl)- pyridine-5-carboxylate); as well as other NMDA modulatory agents. In certain embodiments, exemplary agents for combination can also include inhibitors of brain glycine transporters (e.g. GIyTl w/sarcosine), which can achieve similar effects by raising endogenous glycine levels.

[0054] Other Agents suitable for combination therapy / co-administration and/or co- formulation can include any pharmacologic agent that is recognized by the skilled artisan as being a pharmacologic agent that enhances learning or conditioning. For example, one such class of pharmacologic agents contemplated herein comprises compounds that increase the level of norepinephrine in the brain. Such compounds include those acting as norepinephrine reuptake inhibitors, for example tomoxetine, reboxetine (Edronax or Vestra), duloxetine, venlafaxine (Effexor®), and milnacipran (see, for example, U.S. Pat. No. 6,028,070, the contents of which are herein incorporated by reference), and those compounds that cause release of norepinephrine, for example amphetamine, dextroamphetamine (Dexedrine®), pemoline (Cylert®), and methylphenidate (Ritalin®). Another class of such pharmacologic agents is compounds that increase the level of acetylcholine in the brain, including, for example, compounds that block its breakdown. Examples of such compounds include, but are not limited to, donepezil HCl or E2020 (Aricept®) and tacrine (THA, Cognex®), which inhibit cholinesterase activity.

[0055] As used herein, "psychotherapy" includes any type of psychotherapy that is suitable for the particular psychiatric disorder for which the individual is undergoing treatment. Suitable methods of psychotherapy may include exposure-based psychotherapy, cognitive psychotherapy, and psychodynamically oriented psychotherapy. See, for example, Foa (2000) J. CHn. Psych. 61(suppl. 5):43-38. Exemplary protocol may include adjunctive pharmacotherapy, behavioral modification therapy, or behavioral therapy.

[0056] As used herein, extinction conditioned by drug addiction and extinction conditioned by fear are based on divergent mechanisms. Drug addicts can be "self-medicating" in response to their anxiety/phobias/etc. , but the underlying mechanisms involved in these pathological conditions is distinct at the neurobiological and neurocircuitry levels. On a physiologic level, for example, response to drugs of abuse involves the so-called "reward pathway", the dopaminergic projection from the ventral tegmental area to the nucleus accumbens and the prefrontal cortex (Roy A Wise, in J Comp Neurol 493:115-121 (2005)).

[0057] As used herein, "fear conditioning" can be characterized in whole or in part by a rapid, "single trial" type of conditioning protocol that is usually accomplished in one day. Fear conditioning can involve the use of aversive stimuli (e.g. shock), whereas self-administration can involve the use of appetitive stimuli (e.g. rewarding drug). Fear conditioning can involve the sensory cortex, thalamus and both basolateral and central nuclei of the amygdale (Phelps & LeDoux in Neuron, Vol. 48, 175-187, October 20, 2005). "Self-administration" behavior can develop over several days and eventually involve a form of "habit learning" in addition to any "associative learning" that has occurred following acquisition of the drug-seeking behavior.

[0058] As used herein, "addiction" can include conditions characterized by a persistent desire or compulsion to use a stimulus (e.g. alcohol, drugs, cocaine, food, sexual activity, gambling, shopping). Addictive disorder can be characterized in whole or in part by, for example, a loss of control of drug intake, a reduction in the level of other activities due to over stimulation (e.g. drug use), a desire for continued usage thereof despite knowledge of harm, marked tolerance, characteristic withdrawal symptoms, and/or an increased negative emotional state or stress when the stimulus is unavailable. [0059] Dosage / Formulation/ Administration

[0060] Pharmaceutical compositions for use in accordance with the present invention may be formulated in conventional manner using one or more physiologically acceptable carriers or excipients.

[0061] Any suitable concentration of active ingredient may be used, where the active ingredient is administered in an effective amount to achieve its intended purpose. Determination of a therapeutically effective amount for a particular active ingredient is well within the capability of persons skilled in the art, especially in light of the detailed disclosure provided herein.

[0062] The specific therapeutically effective dose level for any particular patient will depend upon a variety of factors including the addictive disorder being treated and the severity of the disorder; activity of the specific compound employed; the specific composition employed; the age, body weight, general health, sex and diet of the patient; the time of administration, route of administration, and rate of excretion of the specific compound employed; the duration of the treatment; drugs used in combination or coincidentally with the specific compound employed; and like factors well known in the medical arts.

[0063] Pharmaceutical compositions of the present invention may be formulated for administration by direct injection, inhalation, insufflation, oral, parenteral, mucosal (such as buccal, vaginal, rectal, sublingual), or intravenous administration. Methods of preparing pharmaceutical formulations are well known in the art. Dosage of the pharmaceutical compositions may vary by route of administration. In certain embodiments, exemplary agent D- serine can be administered at about (100 mg/kg) before, during, or after the therapy session.

[0064] In certain aspects, suitable exemplary D-serine may be combined in a "cocktail" of compounds to facilitate the effects of extinction to reduce the rate of relapse.

[0065] The timing of administration and therapeutically effective amount or dose of the particular pharmacologic agent used will depend on the pharmacologic agent itself, with the particular timing and dose selected in order to ensure that a therapeutically effect level of the pharmacologic agent is present in the individual being treated at the time of psychotherapy. In general, the timing of administration will be within about 24 hours before psychotherapy, more preferably within about 12 hours, and still more preferably within about 6 hours.

[0066] For D-cycloserine, a time of administration can be within, for example, about 3-8 hours before psychotherapy. For this exemplary pharmacologic agent, dosage levels can include a low dose level of between about 30-100 mg, and a high dose level of between about 400-500 mg. In one embodiment, D-cycloserine is administered in combination with D-alanine to minimize any potential gastrointestinal effects of this pharmacologic agent.

[0067] The therapeutically effective dose of the pharmacologic agent can be administered using any medically acceptable mode of administration. Although the skilled artisan would contemplate any of the modes of administration known to one of ordinary skill, preferably the pharmacologic agent is administered according to the recommended mode of administration, for example, the mode of administration listed on the package insert of a commercially available agent.

[0068] A subject undergoing treatment with the methods of the invention exhibits an improvement in one or more symptoms associated with the psychiatric disorder. For a description of the relevant symptoms, see, for example, the DSM-IV ((1994) Diagnostic and Statistical Manual of Mental Disorders (4th ed., American Psychiatric Association, Washington D. C)), which is herein incorporated by reference. The efficacy of the methods of the invention can be assessed using any clinically recognized assessment method for measuring a reduction of one or more symptoms of the particular psychiatric disorder.

[0069] In certain embodiments, the exemplary NMDA modulatory agent (e.g. D-serine, DCS, sarcosine, glycine) is administered before, during, or after the behavioral extinction session. In certain embodiments, D-serine may be administered at about 30mg/kg/day or 2g/day. In other embodiments, D-cycloserine may be administered at about 50 mg/day. In certain other embodiments, glycine may be administered at about 0.8 g/kg/day (or 60g/day). In yet another embodiment, sarcosine may be administered at about 2 g/day. [0070] Administration may comprise a single exposure of the subject to the therapeutically effective amount of the pharmacologic agent that enhances learning or conditioning, where exposure to the pharmacologic agent occurs within about 1, 2, 3, 4, 5, 6, 8, 10, 12, 16, 18, 20, 24 or more hours prior to initiating the session of psychotherapy. A full course of treatment for the psychiatric disorder entails at least one session of this combination therapy protocol.

[0071] The exemplary NMDA modulating agents may be naked (i.e. non- formulated) or formulated in a variety of carrier agents such as, but not limited to, polymers, nanoparticles, cationic lipids/liposomes (DOTAP, DOPE, cholesterol, etc.), cell-penetrating peptides, protein/immunoglobulin or polyelectrolyte transfection reagents. Compositions may include conjugation of carriers (e.g. peptides or cholesterols) or formulation (mixing).

[0072] Pharmaceutically acceptable carrier can includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible. In one embodiment, the carrier is suitable for parenteral administration. Preferably, the carrier is suitable for administration into the central nervous system (e.g., intraspinally or intracerebrally). Alternatively, the carrier can be suitable for intravenous, intraperitoneal or intramuscular administration. In another embodiment, the carrier is suitable for oral administration. Pharmaceutically acceptable carriers include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, use thereof in the pharmaceutical compositions of the invention is contemplated. Supplementary active compounds can also be incorporated into the compositions.

[0073] Therapeutic compositions typically must be sterile and stable under the conditions of manufacture and storage. The composition can be formulated as a solution, microemulsion, liposome, or other ordered structure suitable to high drug concentration. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol, and the like), and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols such as manitol, sorbitol, or sodium chloride in the composition. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, monostearate salts and gelatin. Moreover, the agonists can be administered in a time -release formulation, for example in a composition which includes a slow release polymer. Many methods for the preparation of such formulations are known to those skilled in the art.

[0074] In certain embodiments, the pharmaceutical agents may also be combined with other therapeutic agents or compounds as co-administration or co-formulation components.

[0075] In certain embodiments, the pharmaceutical formulations comprise exemplary NMDA modulating agents, or salts thereof, of the invention up to 99% by weight mixed with a physiologically acceptable carrier medium such as water, buffer, saline, glycine, hyaluronic acid, mannitol, and the like.

[0076] Pharmaceutical compositions of the present invention can be administered as solutions, suspensions, or emulsions.

[0077] Generally, an effective amount of the exemplary NMDA modulating agents of the invention results in an optimal extracellular concentration or concentration ranges at the surface of the target cell. The dose required to achieve this local concentration will vary depending on a number of factors including the delivery method, the site of delivery, the number of cell layers between the delivery site and the target cell or tissue, whether delivery is local or systemic, etc. The concentration at the delivery site may be considerably higher than it is at the surface of the target cell or tissue.

[0078] An effective amount of a formulation may depend on factors such as the age, race, and sex of the subject. [0079] Acceptable carriers: An acceptable carrier refers to those carriers that cause at most, little to no irritation, provide suitable preservation if needed, and deliver one or more exemplary NMDA modulating agents of the present invention in a homogenous dosage.

[0080] The exemplary NMDA modulating agents may be delivered in solution, in suspension, or in bioerodible or non-bioerodible delivery devices. The exemplary NMDA modulating agents can be delivered alone or as components of defined, covalent conjugates. The exemplary NMDA modulating agents can also be complexed with cationic lipids, cationic peptides, or cationic polymers; complexed with proteins, fusion proteins, or protein domains with nucleic acid binding properties (e.g., protamine); or encapsulated in nanoparticles. Tissue- or cell-specific delivery can be accomplished by the inclusion of an appropriate targeting moiety such as an antibody or antibody fragment.

[0081] For ophthalmic, otic, or pulmonary delivery, an exemplary NMDA modulating agents may be combined with ophthalmologically, optically, or pulmonary acceptable preservatives, co-solvents, surfactants, viscosity enhancers, penetration enhancers, buffers, sodium chloride, or water to form an aqueous, sterile suspension or solution. Solution formulations may be prepared by dissolving the exemplary NMDA modulating agents in a physiologically acceptable isotonic aqueous buffer. Further, the solutions may include an acceptable surfactant to assist in dissolving the inhibitor. Viscosity building agents, such as hydroxymethyl cellulose, hydroxyethyl cellulose, methylcellulose, polyvinylpyrrolidone, or the like may be added to the compositions of the present invention to improve the retention of the compound.

[0082] In certain embodiments, preparation of a sterile ointment formulation can include the combination of the exemplary NMDA modulating agents with a preservative in an appropriate vehicle, such as mineral oil, liquid lanolin, or white petrolatum.

[0083] Sterile gel formulations may be prepared by suspending the exemplary NMDA modulating agents in a hydrophilic base prepared from the combination of, for example, CARBOPOL®-940 (BF Goodrich, Charlotte, N.C.), or the like, according to methods known in the art. VISCOAT® (Alcon Laboratories, Inc., Fort Worth, Tex.) may be used for intraocular injection, for example.

[0084] Other compositions of the present invention may contain penetration enhancing agents such as cremephor and TWEEN® 80 (polyoxyethylene sorbitan monolaureate, Sigma Aldrich, St. Louis, Mo.), in the event the exemplary NMDA modulating agents is less penetrating in the organ or tissue of interest.

[0085] Routes of Administration

[0086] A variety of protocols are available for in vivo delivery and administration of the exemplary agents. In certain embodiments, exemplary NMDA modulating agents may be delivered, for example, via aerosol, buccal, dermal, intradermal, inhaling, intramuscular, intranasal, intraocular, intrapulmonary, intravenous, intraperitoneal, nasal, ocular, oral, otic, parenteral, patch, subcutaneous, sublingual, topical, or transdermal administration. In certain other embodiments, administration may be directly to the lungs, via, for example, an aerosolized preparation, and by inhalation via an inhaler or a nebulizer, for example.

[0087] In certain further embodiments, modes of administration can include tablets, pills, and capsules, all of which are capable of formulation by one of ordinary skill in the art.

[0088] Kits:

[0089] Aspects and embodiments of the present disclosure also provide a kit that includes reagents for modulating NMDA receptor in a subject as adjuvant for psychotherapy. In certain embodiments, the instant disclosure provides a pharmaceutical pack or kit comprising one or more containers filled with the exemplary NMDA receptor modulating agent of the present invention. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration. An embodiment of the invention provides kits that can be used in the above methods. In one embodiment, a kit comprises NMDA modulating agents of the present invention, in one or more containers, and one or more other prophylactic or therapeutic agents useful for combined/augmented psychotherapy.

EXAMPLE 1:

[0090] Example 1 describes the effectiveness of a five-day, between session extinction protocol to reduce the reinstatement of drug seeking behavior primed by noncontingent exposure to contextual cues, conditioned stimuli, or cocaine infusion. The efficacy of extinction was directly compared with the responses measured in another group of abstinent rats that remained in their home cage environments for an equivalent amount of time. The results demonstrate that extinction training is effective in reducing the reinstatement of drug seeking behavior elicited by all three forms of priming. Facilitating the activation of NMDARs during extinction training did not significantly affect the subsequent reinstatement, but inhibiting NMDAR activation resulted in the selective blockade of the extinction effects on drug primed reinstatement. These results indicate that diverse mechanisms participate in mediating the effects of extinction training on the expression of reinstatement of drug seeking behavior.

[0091] In this example, the effectiveness of an extinction training protocol to reduce primed reinstatement responses was compared with the effectiveness of an equivalent period of enforced abstinence. We found that extinction training performed in the drug taking environment significantly reduced reinstatement behavior subsequently primed by either contextual cues, conditioned cues, or cocaine infusion. The ability of extinction to reduce cocaine primed reinstatement was blocked by the systemic administration of the competitive NMDAR antagonist ((±)CPP, 5 mg/kg i.p.) administered prior to each extinction training session. Interestingly, this pharmacological intervention had no impact on the effectiveness of extinction to reduce reinstatement behavior primed by either contextual cues or conditioned cues. These results suggest that an extinction training experience involves multiple mechanisms that can be dissociated into non NMDAR and NMDAR dependent components with respect to the type of reinstatement (i.e. context-, CS-, or drug-induced) being assessed. Materials and Methods

[0092] Animals: Male Sprauge-Dawley rats (Harlan) weighed approximately 300 g at the beginning of the experiment and were housed individually in a temperature and humidity controlled vivarium having a 12 hour light/dark cycle (lights off at 7:00 P.M.). They were given access to food and water ad libitum and were handled daily for 5 days prior to the surgery in order to diminish stress associated with handling. The housing and experimental procedures followed the Guide for the Care and Use of Laboratory Animals and were approved by the local ACUC at the University of Georgia.

[0093] Jugular catheterization protocol: The animals were anesthetized using a combination of ketamine (75 mg/kg), xylazine (10 mg/kg) and acepromazine (1 mg/kg) administered i.p. Depth of anaesthesia was assessed by monitoring the respiration rate and the palpebral and pedal withdrawal reflexes. Under anesthesia, the right jugular vein was isolated and cleaned. The catheter was exteriorized by passing it subcutaneous Iy to the base of the skull, where it was connected to a modified 22 gauge cannula. A silastic catheter (Dow Corning) was then inserted into the vein (4-5 cm) and secured in position with silk sutures (6/0). The animal was then placed in a stereotaxic frame (Stoelting), where the right-angled cannula (Plastics One) was mounted to the top of the skull using dental cement and 4 screws. Immediately after surgery and once daily for 5 days, the animals were treated with gentamicin at a dose of 5 mg/kg, i.v. The catheters were flushed every day with saline prior to each self-administration session and with heparin (10 USP/ml) after the session to maintain the patency of the catheter. Catheter patency was verified daily by drawing blood from the catheter.

[0094] Self-administration environment: The operant chambers (Med associates) were equipped with 2 levers, one "active" and another "inactive" with lights positioned above each lever. The chambers had a rod grid floor, a house light, a speaker/tone generator (2.9 kHz, 10 dB above ambient) and were housed inside enclosures equipped with ventilation fans. A syringe pump was located outside the enclosure. The method for delivering a cocaine infusion was as follows: The modified 22 gauge cannula mounted on the rat's skull was connected to a liquid swivel with PE-50 tubing protected by a metal spring. The swivel was then connected with tygon tubing to the syringe mounted in the infusion pump. Infusion volumes were calculated according to the animal's weight. For cocaine animals, the syringes mounted in the infusion pump contained cocaine hydrochloride (NIDA) dissolved in normal saline at 4 mg cocaine/ml of solution. Each infusion delivered an infusion volume of about 0.125 ml/kg body weight, hence the dose of cocaine self-administered was 0.5 mg/kg/infusion. The MED-PC software program recorded the number of active lever presses, inactive lever presses and the number of infusions.

[0095] Self-administration protocol (days 1-15): The animals having patent indwelling catheters were subjected to self-administration training for a period of 15 days with one session each day. Self-administration training sessions were 90 minutes in duration. Upon entry into the self-administration environment, the house light and the ventilation fan were on. In addition to triggering an infusion, active lever presses had the following programmed consequences: the house light was turned off, and the active lever light/tone (i.e. the CS) was turned on for a period of 30 seconds. Additional responses on the active lever during this 30 second period had no programmed consequences, although the program continued to count the number of active/inactive lever presses and infusions. This "timeout" period protected the animals from cocaine overdose. After this 30 second period the lever light and tone were terminated and the house light came back on. Rats were initially trained for 12 days on an FR-I (fixed ratio schedule- 1 ) schedule in which each active lever press outside the timeout period triggered the programmed consequences. For the last 3 days of self-administration training, an FR-3 schedule was imposed where 3 active lever presses outside the time out period were required to trigger an infusion and the CS. Each rat was placed in the same operant conditioning chamber throughout the course of the experiment.

[0096] Extinction protocol (days 16-20): After the 15 days of self-administration training, the animals were divided into 4 groups (balanced for cocaine intake): 1) extinguished (saline), 2) extinguished ((±)CPP), 3) extinguished (D-serine), 4) abstinent (saline). All groups received i.p. injections of their respective treatments in their home cage environment. Both the extinguished group 1 and the abstinent group 4 received injections of saline (1 ml/kg). Group 2 received an injection of (±)CPP (5 mg/kg) and group 3 received an injection of D-serine (100 mg/kg). Groups 1-3 underwent extinction training 4-5 hours following their respective daily pharmacological treatments, whereas group 4 rats remained in their home cages. During their extinction training sessions, the animals in the operant chambers were attached to the drug tether but exposed only to the environment stimuli (i.e. diffuse, contextual cues). Responses on the active lever had no programmed consequences during the extinction training phase. For protocol days 16-20, responses on both active and inactive levers, as well as the equivalent "number of infusions" were counted by the software (although as stated above, syringe pumps were not activated during this phase of training). Extinction proceeded for a period of 5 days, with one 90 minute session each day during which the animals in the extinction training groups 1 -3 were taken to the operant chambers. Under these conditions, the animals extinguished their lever pressing behavior to less than 20% of their former activity during self-administration. As previously mentioned, group 4 abstinent animals remained in their home cages throughout days 16-20.

[0097] Reinstatement tests (protocol days 21-24): On days 21-24, all the animals (including the home cage abstinent animals), were placed back in the operant chambers for reinstatement tests. The reinstatement test session conditions were similar to an extinction session in that the animals were exposed only to the contextual cues of the operant chamber environment and the active lever responding were not reinforced by the contingent availability of either CS or US

[0098] Reinstatement to the contextual drug stimuli: On test day 21 , response to the contextual prime was assessed from active lever presses during the first 10 minutes in which the animals were exposed only to the contextual cues of the drug environment.

[0099] Reinstatement to the CS cues: Later during the same test session on day 21 , lever presses evoked in response to a CS presentation were then assessed. As the CS is expected to evoke an immediate response from animals, we delivered a single, noncontingent presentation of the CS at the 40^th minute of the 90 minute test session. Thus the initial 40 minutes of the 90 minute session served as an extinction period to allow lever presses initiated by exposure to contextual stimuli to subside before the CS reinstatement test. The response to the noncontingent CS was quantified as the number of responses during the first 10 minutes following the priming event (t=40-50 min). [00100] Reinstatement to the drug prime: Response to the drug prime stimulus was assessed on days 22-24. We tested the reinstatement of drug seeking behavior using 3 different doses (0.25 mg/kg, 0.5 mg/kg and 1 mg/kg) of cocaine on three consecutive days (22^nd 23^rd and 24* day), respectively. A single, noncontingent drug prime was programmed to be infused intravenously by the syringe pump at the 40^th minute of the 90 minute session on these 3 US reinstatement test days. Again, the initial 40 minutes of the 90 minute session served as an extinction period which allowed lever presses initiated by exposure to contextual stimuli to subside before the US reinstatement test. Drug seeking behavior elicited by the different doses of cocaine was quantified from the number of responses on the active lever following the drug prime for 30 minutes immediately after the priming event (t=40-70 min).

[00101] Drugs: Cocaine hydrochloride was a gift from NIDA (RTI), -3(-2 carboxipiperazin-4-yl)-propyl-l-phosphonic acid ((±)CPP) and D-serine were obtained from Sigma (St. Louis). D-serine and (±)CPP were administered in the home cage environment approximately 4 hours prior to the extinction sessions on protocol days 16-20. These compounds have long-lived effects when administered i.p. at the indicated doses, Hashimoto A, Chiba Y. Effect of administration of D-serine on the levels of D- and L-serine in several brain areas and periphery of rat. Eur J Pharmacol, 2004;495: 153-158, Hernandez RV, Derrick BE, Rodriguez WA Martinez JL. (±) CPP, an NMDA receptor antagonist, blocks the induction of commissural- CA3 LTP in the anesthetized rat. Brain Res, 1994;656: 215-219, and therefore any state- dependent or acute locomotor effects were minimized by this advance treatment in the home cage environment. The D-serine dose of 100 mg/kg was chosen in order to avoid possible nephrotoxic effects, Williams RE, Jacobsen M, Lock EA. IH NMR pattern recognition an 3 IP NMR studies with C-serine in rat urine and kidney, time- and dose-related metabolic effects. Chem Res Toxicol, 2003; 16: 1207-1216, while still affecting learning. Stouffer EM, Petri HL, Devan BD. Effect of D-serine on a delayed match-to-place task for the water maze. Behav Brain Res, 2004; 152: 447-452. The (±)CPP dose of 5mg/kg has been shown to disrupt synaptic plasticity processes in the hippocampal formation. Villarreal DM, Do V, Haddad E, Derrick BE. NMDA receptor antagonists sustain LTP and spatial memory: active processes mediate LTP decay. Nat Neurosci, 2002;5: 48-52. [00102] Statistics: ANOVA followed by Bonferroni's post hoc tests, Repeated Measures ANOVA, and paired or unpaired t-tests were applied as indicated using Sigma Stat software. A value of p < 0.05 was taken as a significant result.

[00103] Results

[00104] Cocaine self-administration and extinction of the drug seeking behavior:

[00105] Animals having indwelling jugular catheters were trained to self-administer cocaine in an operant chamber environment for 15 consecutive days. During the daily 90-minute sessions, rats were initially trained on an FR-I schedule for first 12 days and switched to an FR-3 schedule for the last 3 days of self-administration training. The transition to the FR-3 schedule was done to increase the number of active lever pressing responses. Animals typically achieved stable self-administration by day 10 of training, and the FR-3 schedule did not significantly alter the number of earned infusions per session (Figure 1). Over the entire fifteen day self- administration training phase the average total number of infusions earned was 334 ± 12, or the equivalent of approximately 11 mg/kg/day of cocaine per animal. There was no significant difference in the average number of infusions earned per animal among the four different groups of self-administration rats utilized for the reinstatement studies described in this report.

[00106] After 15 days of SA, the animals were subjected to either an extinction training phase (extinction groups) in the same operant chamber environment for 90 minute sessions in the absence of both CS and US (i.e. the active lever had no programmed consequences) for a period of 5 days (Figure 1, protocol days 16-20), or they were kept forcibly abstinent in their home cage environment (abstinent group). Active and inactive lever presses were monitored during the extinction sessions and it was found that the animals extinguish their drug seeking behavior under these conditions. Evaluation of drug seeking behavior between extinction sessions demonstrates that lever pressing activity observed on second-fifth days of extinction is significantly decreased as compared with either the final day of self-administration or the first day of extinction (Figure 2A). Conversely, the second-fifth days' activities were not significantly different from each other. [00107] Reinstatement of drug seeking behavior:

[00108] Evaluation of drug seeking behavior within an extinction session illustrates that the majority of lever pressing activity occurs during the initial ten minutes in the operant chamber environment (Figure 2B), suggesting that environmental contextual cues are priming this response. Following this initial burst of activity, active lever pressing diminishes rapidly. As illustrated during the fifth extinction session on protocol day 20, active lever responses are minimal (< 2) by 20-30 minutes and remain low for the remainder of the 90 minute session (Figure 2B). This within session response pattern was observed during all extinction days (data not shown). Therefore, during the reinstatement experiments involving the noncontingent presentation of either CS or US stimuli, the priming event was delivered 40 min into the test session. A temporal distinction can thus be made between the drug-seeking activity induced by introduction to the operant chamber environment (i.e. activity during the first ten minutes) versus the subsequent activity induced via noncontingent presentation of priming events delivered later within the same test session.

[00109] The effects of extinction training versus enforced abstinence on reinstatement behavior.

[00110] Reinstatement was induced using three forms of priming stimuli: contextual cues, conditioned cues, and drug prime. Once the animals underwent either extinction training or enforced abstinence for a period of 5 days (days 16-20), they were tested for the reinstatement of drug seeking behavior to the contextual stimuli and the conditioned stimuli on day 21, and to cocaine on days 22-24.

[00111] Contextual reinstatement induced by diffuse environmental cues was assessed during the first ten minutes of the test session conducted on day 21. The level of responding on the active lever in the extinguished (saline) group of rats during this period was 6.4 ± 0.9 (n=22, ** p<.01, Figure 3), which is significantly decreased compared with responding during the same period on day 16 in these animals (34.5 ± 4, n=22). The abstinent (saline) group which were kept in the home cage environment for 5 days showed a significantly greater level of responding (41 ± 5.3, n=14) on day 21 as compared with the extinguished (saline) group. Although increased, this level of responding in the abstinent (saline) group during their initial "extinction" experience on day 21 was not significantly different as compared with the extinguished (saline) group on their initial extinction training experience on day 16. These results suggest that the 5- day extinction training experience decreased the efficacy of the contextual cues present in the operant chamber environment to provoke drug seeking behavior.

[00112] Until time=40 min of the day 21 reinstatement test session, the animals experienced extinction conditions. At this point, a single, noncontingent presentation of the discrete CS complex was delivered for a period of 30 seconds and active lever responding for the next 10 min was measured as an indication of the reinstatement of drug seeking behavior evoked by the CS (Figure 4). As previously described for extinction conditions, active lever presses had no programmed consequences at any time during these test sessions. In addition to the active lever presses, the inactive lever presses were also monitored so as to ensure that the noncontingent CS prime was in fact inducing activity previously associated with cocaine infusion. In order to confirm that any responding due to contextual cues had subsided by the time of the CS reinstatement test, active lever pressing during a "pre -prime" ten minute period of time (t=30-40) was also assessed and compared with the cue-induced "post-prime" level of reinstatement (t=40-50, Figure 4A). Results for both the extinguished (saline) and abstinent (saline) groups of rats tested in this manner are illustrated for 10 min bins of time before and following the CS priming event. This analysis (Figure 4B) showed that active lever pressing activity was significantly increased in the ten minute period immediately following the CS prime in both the extinguished (saline) group (0.4 ± 0.3 vs. 3.7 ± 1.0, n= 22, * p<0 05) and the abstinent (saline) group (2.3 ± 1.1 vs. 8.1 ± 2.2, n=14, * p<0.05, Figure 4B) as compared with the ten minute period immediately before the CS prime, demonstrating the effectiveness of the protocol in evoking drug seeking behavior. In addition, the magnitude of post-prime responding in the abstinent (saline) group was significantly greater than that of the extinguished (saline) group (* p<0.05), suggesting that an extinction training experience decreases the efficacy of non contingent CS cues to trigger responses on the active lever. Importantly, the level of responding during the same period of time (i.e. 40-50 min) during the final day of self-administration (day 15) in these animals was 9.3 ± 0.8 and 8.1 ± 0.8 for the extinguished (saline) and the abstinent (saline) groups, respectively. The close agreement in terms of the magnitude of the response in the abstinent animals indicates that a genuine reinstatement of drug seeking had occurred in response to the CS priming event, and that extinction training reduced this form of primed reinstatement. Cocaine-induced reinstatement was tested on the next 3 consecutive days (protocol days 22-24) at 3 different priming doses (0.5x: 0.25 mg/kg, Ix: 0.5 mg/kg, 2x: 1 mg/kg) with a single, noncontingent intravenous infusion of drug delivered at time=40 minute of the session at the respective dose on each day. The active lever responding for the next 30 minutes was then measured as an indication of the reinstatement of drug seeking behavior evoked by the US stimuli. The dose-response results are plotted to demonstrate the shift in the sensitivity to cocaine-induced drug seeking activity (Figure 5). At the Ix dose, the extinguished (saline) group response on the active lever was 8.7 ± 2.4 (n=21), and whereas abstinent (saline) group responses were significantly greater at 26.5 ± 6.9 (n=14, * p<0.05). A similar distinction was observed for the 2x dose, as the responses from the extinguished (saline) and abstinent (saline) groups were 12.9 ± 2.5 (n=21) and 25.5 ± 6.6 (n= 11, * p<0.05), respectively. As observed with both the contextual and CS tests, these drug prime reinstatement results illustrate the effectiveness of extinction training in reducing sensitivity to cocaine-induced drug seeking as compared to an equivalent period of enforced abstinence. Again, the level of responding during the same period of time (i.e. 40-70 mm) during the final day of self-administration (day 15) in these animals was 27.6 ± 1.9 and 24.0 ± 1.0 for the extinguished (saline) and the abstinent (saline) groups, respectively. As mentioned previously with the CS priming test, the close agreement in terms of the magnitude of the response in the abstinent animals indicates that a genuine reinstatement of drug seeking had occurred during this period of time in response to the noncontingent US priming events. Finally, in smaller groups of these extinguished (saline) and the abstinent (saline) conditions, the animals were tested on day 25 with a saline (0.Ox) prime to test for any conditioned effects of the noncontingent cocaine primes that might accumulate over days 22-24. No evidence for such an effect was observed, as there was no change in active lever pressing following the saline prime, as responding was 2.3 ± 1.0 (n=8) and 1.6 ± 0.8 (n=4) for the extinguished (saline) and the abstinent (saline) groups, respectively).

NMDAR involvement in the effects of extinction training on reinstatement behavior. [00113] The role of NMDARs in the extinction process was also evaluated in two additional groups of extinguished rats treated with either D-serine (a coagonist of NMDAR at the glycine site), or (±)CPP (a competitive antagonist of NMDAR). These compounds were administered (D-serine: 100 mg/kg i.p., (±)CPP: 5 mg/kg i.p.) in the home cage environment prior to the extinction sessions (see Methods). Over the course of the 5-day extinction phase carried out on days 16-20, treatment with D-serine facilitated the progression of extinction such that by the third session (i.e. day 18), active lever responding was significantly lower than that observed in the saline treated group (* p<0.05), although both groups reached a similar level of responding by the end of the extinction phase (Figure 6). Treatment with (±)CPP had no discernable effect on the progression of extinction, as active lever responding was not significantly affected on any day of the extinction protocol. By protocol day 20, the final extinction day, all groups exhibited similar levels of drug-seeking behavior during the 90 minute session.

[00114] Contextual reinstatement following extinction training was again assessed during the first ten minutes of the test session conducted on protocol day 21 as described previously for Figure 3. The level of responding on the active lever in the saline group of rats during this period was 6.4 ± 0.9 (n=22), and both the D-serine and (±)CPP treated animals showed similar levels of responding (6.4 ± 1.3 (n=l 5), 8.7 ± 1.8 (n= 17) respectively, Figure 7A). Thus, neither positive modulation (w/D-serine) nor competitive antagonism (w/(±)CPP) of NMDAR activity during extinction training had significant impact on the subsequently measured contextual reinstatement as compared with the saline treated control group following a five-day extinction protocol.

[00115] In order to investigate the effects of NMDAR activity during extinction on CS- induced reinstatement, active lever pressing was again measured during a "pre -prime" ten minute period of time as well as the "post prime" period (Figure 7B). This analysis showed that active lever pressing activity was significantly increased in the ten minute period immediately following the CS prime in both the D-serine (0.0 ± 0.0, 3.4 ± 1.2, n=15, * p<0.05) and (±)CPP (0.2 ± 0.1, 3.6 ± 1.1, n=17, ** p<0.01) treated groups as compared with the ten minute period immediately before the CS prime. However, as the magnitude of post prime responding in these treatment groups was not significantly different from that of the saline treated extinguished group (3.7 ± 1.0, n=22, ** p<0.01), no role for NMDAR activity during the extinction training experience is indicated for this CS-induced reinstatement outcome.

[00116] Finally, cocaine-induced reinstatement was tested on the next 3 consecutive days (protocol days 22-24) at 3 different priming doses (0.5x: 0.25mg/kg, Ix: 0.5mg/kg, 2x: lmg/kg) with a single, noncontingent intravenous infusion of drug delivered at time=40 min of the session at the respective dose on each day. The active lever responding during the next 30 minutes was measured as an indication of the reinstatement of drug seeking behavior evoked by the US stimuli. The dose-response results are plotted to demonstrate the shift in the sensitivity to cocaine-induced drug seeking activity (Figure 7C). Treatment with D-serine during extinction did not alter reinstatement at any of the priming doses tested as compared with the saline treated group. In contrast, the (±) CPP treated group response was significantly greater than that of the saline group at the Ix dose (20.4 ± 4.7 (n=13) vs. 8.7 ± 2.4 (n=21), respectively, * p<0.05). A similar trend was also observed at the 2x dose, although the response from the (±)CPP group was not significantly different (23.6 ± 7.5, p=0.11) from that of the saline treated control group (12.9 ± 2.5). These results illustrate that the ability of extinction to reduce drug primed reinstatement (c.f. Figure 5) is dependent upon the activation of NMDARs during the training protocol.

[00117] In sum, altering NMDAR activity during extinction training did not affect contextual or CS primed reinstatement. However the blockade of NMDARs during the extinction protocol did affect US (cocaine) primed reinstatement and the magnitude of responding in this group was similar to that of the abstinent group. This suggests that the effectiveness of a prior extinction training experience to reduce the reinstatement response to drug priming involves an NMDAR dependent mechanism, and is therefore distinguishable from the mechanisms underlying the effects of extinction on contextual or CS primed reinstatement.

[00118] Discussion

[00119] This example illustrates the effectiveness of an extinction training protocol to reduce primed reinstatement as compared with an equivalent period of enforced abstinence. This was a prerequisite step in continuing the effort to investigate the mechanisms underlying the effectiveness of extinction training to reduce reinstatement. We have discovered that in addition to reducing active lever responding when placed back into the drug paired environment (Figure 3), extinction training can also significantly reduce the primed drug seeking response following exposure to either CS or US cues (Figures 4&5).

[00120] In the rat self-administration model for craving and/or relapse, the presentation of discrete, drug associated stimuli can be used to prime the reinstatement of drug seeking behavior. See RE. Neural substrates of cocaine-cue associations that trigger relapse. Eur J Pharmacol, 2005;526; 140-146. Since an early study that employed the use of CS cues presented in a noncontingent manner , de Wit H, Stewart J. Reinstatement of cocaine -reinforced responding in the rat. Psychopharmacology (Berl), 1981;75: 134-143, the majority of the subsequent work in rats has used a contingent method of assessing CS induced reinstatement. Shaham Y, Miczek KA. Reinstatement-toward a model of relapse. Psychopharmacology, 2003; 168: 1-2. This issue has been a point of contention concerning the validity of the reinstatement protocol for modeling the human condition in which self-reported craving can be triggered by passive exposure to drug associated cues. As craving in humans can be induced via noncontingent presentation of these cues, it has been argued that the CS reinstatement protocol should employ this form of priming as well. Katz JL, Higgins ST. The validity of the reinstatement model of craving and relapse to drug use. Psychopharmacology, 2003; 168: 21-30. In our study, we have determined conditions under which a single, noncontingent presentation of the CS or US results in a significant increase in drug seeking behavior. In order for this effect to be observed, it was important to utilize a within session design and to select an appropriate period of time for the analysis of the response. By waiting until the immediate, context stimulated responding had dissipated (Fig. 2B), the relatively low remaining level of activity could be effectively compared with the responses on the active lever triggered by the noncontingent CS or US presented at time = 40 minutes into the test session.

[00121] The neural circuitry underlying reinstatement has been the subject of several studies, recently reviewed by See. See RE. Neural substrates of cocaine-cue associations that trigger relapse. Eur J Pharmacol, 2005; 526; 140-146. Evidence suggests that the BLA, the dorsal medial prefrontal cortex, and the lateral orbitofrontal cortex participate in the expression of reinstatement following exposure to CS cues. In addition, the dHF is selectively involved in reinstatement following exposure to contextual cues, Fuchs RA, Evans KA, Ledford CC, Parker MP, Case JM, Mehta RH, See RE. The Role of the Dorsomedial Prefrontal Cortex, Basolateral Amygdala, and Dorsal Hippocampus in Contextual Reinstatement of Cocaine Seeking in Rats. Neuropsychopharmacology, 2005;30: 296-309 and both the NAc, Grimm JW, See RE. Dissociation of Primary and Secondary Reward-Relevant Limbic Nuclei in an Animal Model of Relapse. Neuropsychopharmacology, 2000;22: 473-479 and the vHF Sun W, Rebec GV. Lidocaine inactivation of ventral subiculum attenuates cocaine-seeking behavior in rats. J Neurosci, 2003 ;23: 10258-10264, are involved in reinstatement following exposure to drug prime. Stress induced via foot shock can evoke reinstatement, Erb S, Shaham Y, Stewart J. Stress reinstates cocaine-seeking behavior after prolonged extinction and a drug-free period. Psychopharmacology, 1996;128: 408-412, and this effect may involve the BNST (Erb S, Stewart J. A Role for the Bed Nucleus of the Stria Terminalis, But Not the Amygdala, in the Effects of Corticotropin-Releasing Factor on Stress-Induced Reinstatement of Cocaine Seeking. J Neurosci, 1999; 19: 1-6) and the VTA. Wang B, Shaham Y, Zitzman D, Azari S, Wise RA, You Z-B. Cocaine experience establishes control of midbrain glutamate and dopamine by corticotropin-releasing factor: A role in stress-induced relapse to drug seeking. J Neurosci, 2005;25: 5389-5396. Finally, the participation of the dlCPu region is required for either context or CS cued reinstatement following periods of either abstinence or extinction, Fuchs RA, Branham RK, See RE. Different Neural substrates mediate cocaine seeking after abstinence versus extinction: A critical role for the dorsolateral caudate-putamen. J Neurosci, 2006;26: 3584-3588, whereas the participation of the BLA or the dmPFC is not required for reinstatement following a period of abstinence (as opposed to a period of extinction, as in the earlier studies cited above). In sum, it is evident that the reinstatement evoked via these different types of priming stimuli can differentially involve distinct regions of the brain, and therefore may also recruit different mechanisms at the synaptic level for the processing, storage, and recall of such information.

[00122] In contrast to the self-administration behavioral model, the mechanisms of extinction training have been extensively investigated in other paradigms such as fear conditioning, inhibitory avoidance, spatial navigation and conditioned taste aversion. Cammarota M, Bevilaqua LRM, Barros DM, Vianna MRM, Izquierdo LA, Medina JH, Izquierdo I. Retrieval and the Extinction of Memory. Cellular and Molecular Neurobiology, 2005;25: 465-474. Extinction likely involves new learning, Bouton ME, Westbrook RF, Corcoran KA , Maren S. Contextual and Temporal Modulation of Extinction: Behavioral and Biological Mechanisms. Biol Psychiat, 2006;60: 352-60 and at the molecular level, both NMDAR and nonNMDAR dependent forms of synaptic plasticity are thought to contribute to this type of learning. Although some studies have indicated that extinction learning in conditioned taste aversion (Berman DE, Dudai Y. Memory extinction, learning anew, and learning the new: Dissociations in the molecular machinery of learning in cortex. Science, 2001 ;291: 2417-2419) or conditioned fear (Akirav I, Khatsrinov V, Vouimba R-M, Merhav M, Ferreira G, Rosenblum K, Maroun M. Extinction of conditioned taste aversion depends on functional protein synthesis but not on NMDA receptor activation in the ventromedial prefrontal cortex. Learn Mem, 2006; 13: 254-258) does not require the activation of NMDARs, other reports have indicated a critical role for NMDARs. Baker JD, Azorlosa JL. The NMDA antagonist MK-801 blocks the extinction of pavlovian fear conditioning. Behav Neurosci, 1996; 110: 618-620. Falls WA, Miserendino MJ, Davis M. Extinction of fear-potentiated startle: blockade by infusion of an NMDA antagonist into the amygdala. J Neurosci, 1992; 12: 854-863. Santini E, Muller RU, Quirk GJ. Consolidation of extinction learning involves transfer from NMD A-independent to NMD A-dependent memory. J Neurosci, 2001 ;21: 9009-9017. Our results with cocaine self-administration have demonstrated that antagonism of NMDARs during extinction had no acute effect on responding within a session, nor was there any effect on the progression of extinction over the five day protocol. However, there was a trend in the NMDAR coagonist treated group for enhanced extinction within each daily session (particularly evident at day 18), but again there was no significant difference in the level of responding by the end of the extinction training protocol (Fig. 6). Thus although the (±)CPP results demonstrate that NMDAR activation is not required for the normal progression of extinction, the D-serine results suggest that NMDAR activation may facilitate extinction.

[00123] As far as we are aware, the mechanism(s) underlying the effects of extinction to reduce the reinstatement of drug seeking behavior have not been described. As mentioned previously, since different types of priming stimuli have been shown to involve different neural substrates, it is reasonable to propose that the effects of extinction training on these various forms of reinstatement might also be linked to different mechanisms during the extinction learning process. Our results demonstrate that although extinction training is effective in reducing the reinstatement evoked by context, CS, and cocaine priming (Figs 3-5), the underlying mechanism involves both NMDAR dependent and NMDAR independent components. This was illustrated in Fig. 7, where only the effect of extinction on the reinstatement primed via cocaine administration was sensitive to NMDAR blockade during extinction training (Fig. 7C), whereas extinction was equally effective despite NMDAR antagonist treatment in the case of either context or CS primed reinstatement (Fig. 7A & B). Based on these findings, we expected that treatment with the NMDAR coagonist D-serine would enhance the effects of extinction training such that the magnitude of cocaine primed reinstatement responses would be decreased relative to the saline treated group. This expectation was not met (Fig. 7C), and we suggest that overtraining is likely to occur by the end of our five day protocol such that the effects of extinction are maximal and cannot be significantly enhanced. Future studies that assess the efficacy of a shorter extinction training period will directly test this hypothesis and indicate whether enhancing the activity of NMDARs dining extinction training might be an effective means by which to significantly decrease the duration and/or number of extinction sessions required to reduce the magnitude of the drug primed reinstatement response. In any case, the demonstration of the participation of NMDARs in the effects of extinction to reduce cocaine primed reinstatement indicates that pharmacotherapy targeting these receptors may be useful, and it is tempting to speculate that just as different brain regions are involved in mediating the various forms of primed reinstatement of drug-seeking behavior, different synaptic mechanisms (i.e. both NMDAR dependent and NMDAR independent synaptic plasticity) may also be involved in mediating the effects of extinction on primed reinstatement.

[00124] The mechanisms involved with the resulting effects of extinction training as they may relate to the self-administration of addictive substances have been investigated at the molecular level in the ventral tegmental area and nucleus accumbens regions of the brain. Self DW, Choi K-H, Simmons D, Walker JR, Smagula CS. Extinction training regulates neuroadaptive responses to withdrawal from chronic cocaine self- Administration. Learn Mem, 2004; 11: 648-657. These studies have demonstrated that an extinction training experience can restore tyrosine hydroxylase to predrug levels in the NAc shell, whereas an equivalent abstinent period showed a persistent deficit in TH protein levels. Schmidt EF, Sutton MA, Schad CA, Karanian DA, Brodkin ES, SeIfDW. Extinction training regulates tyrosine hydroxylase during withdrawal from cocaine self-administration. J Neurosci, 2001;21 : RC137. Similarly, a down regulation of NMDA receptor NRI subunit during abstinence is reversed by extinction. Self DW, Choi K-H, Simmons D, Walker JR, Smagula CS. Extinction training regulates neuroadaptive responses to withdrawal from chronic cocaine self- Administration. Learn Mem, 2004; 11: 648-657. Finally, an extinction induced upregulation of GIuRl AMPA receptors occurs in the NAc shell (Sutton MA, Schmidt EF, Choi K-H, Schad CA, Whisler K, Simmons D, Karanian DA, Monteggia LM, Neve RL, SeIf DW. Extinction-induced upregulation in AMPA receptors reduces cocaine-seeking behaviour. Nature, 2003 ;421: 70-75), and an upregulation of TH also has been observed in the VTA following extinction training (Schmidt EF, Sutton MA, Schad CA, Karanian DA, Brodkin ES, SeIfDW. Extinction training regulates tyrosine hydroxylase during withdrawal from cocaine self-administration. J Neurosci, 2001;21: RC 137.) All of these extinction induced neuroadaptations would be expected to act in a compensatory manner in order to counteract the drug induced depression of the synapses in the NAc shell (Thomas MJ, Beurrier C, Bonci A, Malenka RC. Long-term depression in the nucleus accumbens: a neural correlate of behavioral sensitization to cocaine. Nat Neurosci, 2001;4: 1217-1223). However, it is important to keep in mind that these changes have been measured as a result from the animal having undergone extinction, and are not necessarily direct contributors to the learning mechanisms at work during the extinction training process itself that underlie the subsequent effects on the expression of primed reinstatement.

[00125] In conclusion, herein provide a clear measure of the effectiveness of extinction training in reducing the reinstatement of drug seeking behavior primed by noncontingent exposure to context, CS, or drug primes as compared to an equivalent period of enforced abstinence. In addition, the effectiveness of extinction was differentially sensitive to pharmacological intervention with an NMDAR antagonist administered during the training protocol, indicating that multiple forms of synaptic plasticity can be utilized during this form of new learning that are specific to the different types of priming and the associated neural circuitry involved in mediating the reinstatement of drug seeking behavior. Significant gains may be achieved when several therapeutic approaches are combined.

EXAMPLE 2

[00126] Male Sprague Dawley rats were trained to self-administer cocaine (0.5 mg/kg/infusion) during 90 minute sessions over 15 consecutive days. After the self- administration phase the animals were divided into two groups during a withdrawal phase of 5 days (days 16-20), the first group was an extinction group and the second was an enforced abstinent group. During the extinction phase, all the animals were deprived of both the primary reinforcer (drug) and the conditioned reinforcers (cue light and tone). The extinction training group was divided based on the treatments they received during the extinction phase: 1) a control extinguished group received saline intraperitoneally (i.p.). 2) a second group was treated with the competitive NMDA antagonist, (±)-3-(2-carboxypiperazin-4-yl)propyl-l-phosphonic acid (CPP; 5 mg/kg i.p.). 3) and a third group was treated with the NMDA receptor coagonist, D-serine (100 mg/kg i.p.). All the animals received the injections 4-5 hours before they were placed in the operant chambers for the 90 minute extinction training sessions. Enforced abstinent animals received saline i.p. and remained in their home cages. During the reinstatement phase, all animals were tested for response to a single noncontingent presentation of the conditioned st th reinforcers (cue prime on the 21 day) or of the primary reinforcer (drug prime on the 22-24 day; 0.25, 0.5 and 1.0 mg/kg cocaine,). Extinguished rats showed reduced reinstatement of drug seeking behavior in response to both the cue and drug prime stimuli as compared with abstinent animals. Rats treated with (±)CPP during extinction showed greater reinstatement in response to drug prime (similar to abstinent animals), whereas reinstatement to cue prime was not affected. D-serine treatment had no significant effects on either reinstatement response. The results indicate that the mechanism by which extinction can reduce drug primed reinstatement is dependent upon NMDA receptor activation during the extinction training.

EXAMPLE 3: (ALSO SEE FIGURE 8)

[00127] Rats were allowed to self-administer cocaine during 90min sessions for 15 days. Three groups of rats experienced a single extinction training session, and were treated with either saline or D-serine (100 mg/kg) before the session, or with D-serine after the session. A fourth group was left in the home cage housing as a standard control for comparison. Following one day without access to cocaine, drug seeking responses are illustrated for a 30min time before "pre" and following a single priming infusion of cocaine "post" in these four groups animals. As compared with the abstinent rats (black filled bars on right), only the D-serine treated groups significantly reduced their lever pressing activity following one day of extinction training.

[00128] Thus, a short period of extinction training that is not effective on its own can be significantly enhanced by administration of the NMDAR coagonist D-serine.

[00129] * * *

[00130] All patents, publications, scientific articles, web sites, and other documents and materials referenced or mentioned herein are indicative of the levels of skill of those skilled in the art to which the invention pertains, and each such referenced document and material is hereby incorporated by reference to the same extent as if it had been incorporated by reference in its entirety individually or set forth herein in its entirety. Applicants reserve the right to physically incorporate into this specification any and all materials and information from any such patents, publications, scientific articles, web sites, electronically available information, and other referenced materials or documents.

[00131] Those of skill in the art, in light of the present disclosure, will appreciate that obvious modifications of the embodiments disclosed herein can be made without departing from the spirit and scope of the invention. All of the embodiments disclosed herein can be made and executed without undue experimentation in light of the present disclosure. The full scope of the invention is set out in the disclosure and equivalent embodiments thereof. The specification should not be construed to unduly narrow the full scope of protection to which the present invention is entitled.

[00132] While a particular embodiment of the invention has been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims. [00133] The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes to the claims that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

[00134] Other embodiments are within the following claims. In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Claims

1. The use of an NMDA receptor modulatory agent in the manufacture of a medicament for the treatment of an addiction disorder comprising administering a therapeutically effective amount of the NMDA receptor modulatory agent alone or in combination with behavioral or psychotherapy.

2. The use claim 1, wherein the NMDA receptor modulatory agent is selected from D-cycloserine, D-serine, 1-aminocyclopropane-carboxylic acid, sarcosine, spermine and spermidine.

3. The use of claim 1, further comprising administration of one or more additional therapeutic agents.

4. The use of claim 3, wherein the additional therapeutic agent is another NMDA modulatory agent.

5. The use of claim 3, wherein the additional therapeutic agent is one or more of memory/cognitive enhancers, cognitive enhancers, calcium channel agonists, glycine transporter inhibitors, norepinephrine reuptake inhibitors, norepinephrine releasing agents , and acetocholinesterase inhibitors.

6. The use of claim 2, wherein the NMDA modulatory agent is D-serine.

7. The use of claim 2, wherein the NMDA modulatory agent is D-cycloserine.

8. The use of any of claims 1-7, wherein the behavioral therapy or psychotherapy comprises extinction therapy or training.

9. The use of an NMDA receptor modulatory agent in the manufacture of a medicament for preventing the relapse of an addictive disorder comprising administering a therapeutically effective amount of the NMDA receptor modulatory agent alone or in combination with behavioral or psychotherapy.

10. The use of claim 9, wherein the NMDA receptor modulatory agent is selected from D-cycloserine, D-serine, 1-aminocyclopropane-carboxylic acid, sarcosine, spermine and spermidine.

11. The use of claim 9, further comprising administration of one or more additional therapeutic agents.

12. The use of claim 11 , wherein the additional therapeutic agent is another NMDA modulatory agent.

13. The use of claim 11, wherein the additional therapeutic agent is one or more of memory/cognitive enhancers, cognitive enhancers, calcium channel agonists, glycine transporter inhibitors, norepinephrine reuptake inhibitors, norepinephrine releasing agents , and acetocholinesterase inhibitors.

14. The use of claim 10, wherein the NMDA modulatory agent is D-serine.

15. The use of claim 10, wherein the NMDA modulatory agent is D-cycloserine.

16 The use of any of claims 9-15, wherein the behavioral therapy or psychotherapy comprises extinction therapy or training.

17 The use of an NMDA receptor modulatory agent in the manufacture of a medicament for treating an addiction disorder comprising administering a therapeutically effective amount of D-serine in combination with extinction training.

18. The use of an NMDA receptor modulatory agent in the manufacture of a medicament for treating an addiction disorder comprising administering a therapeutically effective amount of D-cycloserine in combination with extinction training.

19. The use of an NMDA receptor modulatory agent in the manufacture of a medicament for preventing the relapse of an addictive disorder comprising administering a therapeutically effective amount of D-serine in combination with extinction training.

20. The use of an NMDA receptor modulatory agent in the manufacture of a medicament for preventing the relapse of an addiction disorder comprising administering a therapeutically effective amount of D-cycloserine in combination with extinction training.