FR2872045A1 - MEDICAMENTS FOR THE SPECIFIC TREATMENT OF SYMPTOMS OF PARKINSON'S DISEASE - Google Patents

Abstract

Use for manufacturing medicaments for treating the symptoms of akinesia in Parkinson's disease, of compounds corresponding to formula (I) in which-R1 to R4, identical or different from each other, represent: hydrogen, alkyl, aryl , these radicals being optionally themselves substituted, R1 and R2 together can also represent a bridge - (CH2) m-, where m is an integer from 1 to 5, or a bridge X representing a linear combination of m groups hydrocarbons, m being as defined above, and comprising, where appropriate, at least one heteroatom or an X bridge representing a linear combination of p heteroatoms, where p is an integer from 1 to 3, -A1 and A2 represent radicals -COOH, -SO3H or -PO3H2, or their derivatives, - Y represents a hydrocarbon chain - (CH2) n-, n being zero or an integer from 1 to 5, or represents a linear combination of n hydrocarbon groups and at least a heteroatom, or a combination we linear of q heteroatoms, where q is an integer from 1 to 3.

Description

H2N / c02H R2 z

  The invention relates to the use of cyclic analogues of glutamic acid for the manufacture of medicaments for the specific treatment of symptoms of the treatment of symptoms of Parkinson's disease. Parkinson's disease (MP for short).

  PM is a degenerative condition, rare before the age of 45, affecting 1.5% of the population over 65, which affects both men and women.

  During the course of the disease, the degeneration of the dopaminergic neurons of the Black Substance Pars compacta (SNc) is accompanied by a dysfunction of the Base Ganglia (GB), subcortical structures involved in the control of motor skills. These modifications of activity are manifested by reactive hyperactivity of glutamatergic neurons.

  These changes of activity within the GB are responsible for the expression of the main motor disorders observed in the context of PD, namely: akinesia (delay in the initiation of movement) and bradykinesia (slowing down of motor performance), muscle rigidity and resting tremor. To these various motor disorders are added various cognitive impairments, relating to attentional abilities, mnemic, as well as motivational disorders.

  Although the etiology of this pathology is still poorly understood, palliative treatments exist in the human clinic and are mainly aimed at increasing dopamine levels in the SNc target structures by regular administration of its precursor, L-DOPA. . This type of treatment remains the most used at present, but it has several major drawbacks: its effectiveness gradually decreases with the evolution of the disease, and the repetition of the doses and the increase of the doses of L-DOPA leads, after several years treatment, the onset of severe and disabling motor fluctuations and involuntary movements (dyskinesia).

  In order to propose alternative treatment strategies to DOPA therapy, and to better understand the normal and pathological functioning and relationships of the different structures that make up the GB, new avenues of research attempt to characterize the effects of blockage or activation of different neuronal systems whose activity is modified by dopaminergic neurodegeneration.

  In this context, studies carried out in different animal models of PM have shown involvement, metabotropic glutamate receptors (mGluR). Among the different groups of mGluR, the functional role of group III mGluR is still poorly understood. However, the mGluR4 and R7 subtypes of these receptors have the particularity of being expressed at the presynaptic level on certain categories of neurons, which are supposed to be hyperactive during PM, and in particular on the gabaergic neurons of the striatum, which project at the level of the Globus. Pallidus (GP).

  The inventors have studied the involvement of group III mGluRs in the regulation of GB activity. They then found that, surprisingly, selective agonists of group III receptors, and mGluR4 in particular, were able to activate receptors in the GP of experimental models, and to reduce akinesia in these models, showing their regulating effect of gabaergic hyperactivity at GP level and the essential role of this structure in the expression of motor disorders associated with PM.

  The aim of the invention is therefore the use of glutamatergic receptor agonists for the manufacture of medicaments making it possible to specifically treat certain symptoms of PD that are particularly disabling in patients.

  It also aims at a method of treating these symptoms taking advantage of the properties of these agonists.

  The invention thus relates more particularly to the use, in order to manufacture medicaments making it possible to treat the symptoms of akinesia in PD, of compounds characterized in that they correspond to the formula (I) H2N \ / C 02H RI / / Wherein R 1 to R 4, which are identical to or different from each other, represent a hydrogen atom, an alkyl radical or an aryl radical, these radicals being optionally substituted, R1 and R2 together may further represent a - (CH2) m- bridge, where m is an integer of 1 to 5, or an X bridge representing a linear combination of m hydrocarbon groups, m being as defined above, and having, where appropriate, at least one heteroatom such as 0, N or S, or a bridge X representing a linear combination of p 0, N and / or S heteroatoms, where p is an integer of 1 to 3, - A1 and A2 represent -COOH, -SO3H or -PO3H2 radicals, or derivatives thereof such as esters or amides, - Y represents wherein a hydrocarbon chain - (CH2) n-, n being zero or an integer of 1 to 5, or represents a linear combination of n hydrocarbon groups and at least one O, N or S heteroatom, or a linear combination of q heteroatoms; , N and / or S, where q is an integer of 1 to 3.

  These compounds are described in patent EP 0 970 043 in the name of the CNRS and the corresponding patents.

  The invention is preferably directed to the use of a family of monocyclic compounds. They are compounds of formula I in which Y does not exist and the carbons bearing R1 and R2 are not connected to one another by forming one of the aforementioned bridges.

  The invention further relates to the use of another family in which the compounds are also monocyclic and correspond to formula I above, in which the carbons bearing R1 and R2 are not connected to each other forming one of the aforementioned bridges, and Y represents a group or a combination as defined above.

  The invention is also directed to the use of another family wherein the compounds are bicyclic and have the formula I above wherein X or both X and Y are present and are defined as indicated above.

  In a preferred group of compounds of these different families used according to the invention, Al and A2 are identical. In preferred compounds of this group A1 and A2 both represent a carboxyl group, or the corresponding esters or amides.

  In another group of compounds of these different families used according to the invention, Al and A2 are as defined above, but differ from each other.

  Advantageous compounds of these families and groups include substituents R 1, R 2, and / or R 3 and R 4 representing an alkyl or aryl radical, these radicals being optionally substituted.

  By "alkyl" radical is meant according to the invention a radical of 1 to 10 carbon atoms, especially 1 to 5 carbon atoms. By "aryl" radical is meant a mono- or polycyclic aromatic radical. A preferred aryl radical is the phenyl radical.

  The alkyl or aryl radicals may be substituted, for example, with a halogen atom or a hydroxyl group.

  In other advantageous compounds, R 1 and R 2 and / or R 3 and R 4 represent a hydrogen atom.

  The compounds defined above used in accordance with the invention may exist as achiral or chiral molecules, in the form of different diastereoisomers, optionally as racemic, where appropriate in the form of one of the enantiomers.

  The invention is particularly directed to the use of 1-aminocyclopentane-1,3,4-tricarboxylic acid of the formula H 2 N 1 CO 2 H HO 2 C CO 2 H ACPT I = meso-cis ACPT = (1S, 3R, 4S) for manufacturing drugs allowing to treat the symptoms of akinesia in the MP which corresponds, as indicated above, to one of the most disabling symptoms in the patients.

  This compound is designated "ACPT-1" in the patent EP 0 970 043 indicated above.

  The inventors tested the effects of intrapallidal injections of ACPT-I in different experimental MP-like models in rats. The models used during these experiments correspond to models of akinesia (loss of "motor initiation"), induced either by partial bilateral lesion of dopaminergic neurons of the SNc, or by pharmacological blocking of dopamine receptors by haloperidol .

  In order to highlight the effects of treatment with ACPT-1, appropriate behavioral tests (simple reaction time (TR) test and catalepsy test) were used. The TR test is commonly used clinically to evaluate akinetic deficits in Parkinsonian patients (Gauntlett-Gilbert and Brown, 1998). It allows the study of the processes involved in the preparation of movement such as detection and processing of sensory information, planning, programming and triggering movement. The correct execution of the movement (i.e with a temporal constraint) requires a high level of attention and motivation.

  The catalepsy test reveals motor deficits that are similar to akinesia.

  This study therefore relies on the use of experimental models of PM in the rat, in order to characterize the effects of intra-pallidal administration of ACPT-1, mGluR4 agonist, in different behavioral tests to evaluate motor and cognitive abilities.

  Considerable data from the literature on the functional study of dopaminergic systems has been generated by the discovery of a toxin specific for central catecholaminergic neurons, 6-hydroxydopamine (6-OHDA). In rodents, the main effect of this type of neurochemical exclusion aimed at destroying unilateral mesencephalic dopaminergic neurons results in postural asymmetry accompanied by rotational behavior. The use of this approach, which is widely used as a "model of Parkinson's disease" and has led to the identification of important phenomena, however, raises some questions. Parkinson's pathology, whose origin is a unilateral involvement of the neurons of the nigrostriatal system, which evolves very rapidly towards a bilateral pathology. In addition, observed behavioral disturbances can not be detected for dopamine depletion rates lower than 90. Finally, the motor deficits revealed in the rotational behavior do not reflect the importance and the variety of disorders observed in parkinsonian patients. which encompass the motor and cognitive sphere.

  It was therefore obvious to develop a behavioral test that could highlight motor disturbances but also cognitive after suppression of dopaminergic transmission in the rat. This test should also be sensitive enough to detect deficits produced by low dopamine depletions, better able to reflect the early stages of the disease. The inventors have therefore developed a behavioral task, derived from the simple reaction time measurement protocol making it possible to evaluate akinetic deficits in Parkinson's patients. Measuring the performance of animals trained to perform a movement of the paw in response to a light stimulus with a constraint in speed, thus allows to understand the integrative processes necessary for the association between a conditioned stimulus and an appropriate motor response. The animals are trained to maintain a support on a pedal with an anterior paw until the appearance of a light (conditioned or imperative stimulus) for a variable and random duration. They must then release the pedal as quickly as possible to obtain a food reward (see experimental protocol). The motor performances are expressed in number of successful tests, for which the reaction time is measured between the appearance of the light signal and the release of the pedal as well as in number of failures, too early releases of the pedal (movements anticipated) or too late (above an imposed time limit).

  a) Driving components of the TR task In the similar experimental model of Parkinson's disease, bilateral local injections of 6-OHDA were made at the dorsal or ventral striatum (nucleus accumbens) in the projection areas of dopaminergic neurons. The inventors have shown that a partial destruction of the nigrostriated dopaminergic terminations (approximately 60% drop in dopamine levels in the posterior and dorsal portion of the striatum), induced by an injection of 6-OHDA at the level of the striatum, resulted in a hypokinesia, which corresponded to longer reaction times and an increase in "late tests" whereas the destruction of dopaminergic neurons in the mesolimbic pathway did not cause any deficit (Amalric and Koob 1987). These results led to the conclusion that low levels of dopamine depletion in the striatum could produce quantifiable behavioral deficits on specific motor parameters in the rat.

  b) Attentional components in the task of TR Selective attention disorders, a function corresponding to the selection of perceptual information, allowing a better treatment of the selected information, can be expressed in the selection of answers during simple tests. The measurement of the response time in the TR task thus makes it possible to highlight certain information processing operations.

  In drug development, the active ingredients are used in therapeutically acceptable amounts for the chosen mode of administration.

  Thus for oral administration, the drugs are prepared in the form of tablets, capsules, tablets, dragees, capsules, pills, drops, liposomes and the like. Such drugs may contain from 1 to 100 mg of active ingredient per unit, preferably from 2.5 to 50 mg.

  Given the activity of ACPT-1 on the gabaergic pathway, the invention also aims at the development of systemically administrable drugs by injection.

  For administration by injection (intravenous, subcutaneous, intramuscular). The drugs are then in the form of sterile or sterilizable solutions. The doses per unit dose may vary from 0.5 to 50 mg of active ingredient, preferably from 1 to 30 mg.

  The drugs of the invention are useful at the pre-clinical or clinical stage of the disease.

  The invention also relates to a method for treating akinesia in PD, characterized by the administration of at least one compound as defined above, in therapeutically acceptable amounts. It is particularly directed to a method of treating akinesia in PD including the administration of ACPT-1.

  This method is carried out in particular by administering the drugs orally or by injection, according to the forms and amounts indicated above.

  Other features and advantages of the invention will be given in the results reported below to illustrate the invention.

  In these examples, reference is made to Figures 1 to 5 which represent, respectively: Figure 1: Effect of intrapallidal injection of ACPT-I in a catalepsy test.

  A. Median descent latency. The results presented correspond to the medians of latency of descent for each time (TO to T60) after injection of ACPT-I.

  B. Sum of latencies over 60 minutes. The results presented correspond to the total time spent on the bar.

  * p <0.05, Mann Whitney test, significantly different from "Haldol + VEH". # p <0.05, Mann Whitney test, significantly different from "NaC1 + VEH".

  Figure 2: Long-term effects of dopaminergic injury in a simple reaction time test.

  A. Effects on correct answers.

  B. Effects on late responses.

  C. Effects on anticipated responses.

  The results presented correspond to the average SEM of the performances: of the preoperative condition (7 sessions: D-7 to D-1).

  - the short-term postoperative condition (Postl: J10 to J16).

  - of the condition Post2 (J17, 20, 21, 24, 25, 28, 29) - of the condition Post2 (J32, 34,36, 37, 38, 39,40) Lésés: n = 24 / Witnesses: n = 11.

  * p <0.05, t-matched test, significantly different from the preoperative condition ("Pre"). p <0.05, ANOVA, significantly different from the control group for the same condition.

  Figure 3: Effects of dopaminergic injury and PACPT-I intra-pallidal injection in a simple reaction time test.

  A. Distribution of mean TRs in the Pre and Postoperative Periods.

  The results presented correspond to the average SEM of the performances: - of the preoperative condition (7 sessions: D-7 to D-1).

  - the short-term postoperative condition (Posta: J10 to J16).

Wounded: n = 24 / Witnesses: n = 11.

  B. Effect of intra-pallidal injections of PTCA-I on mean TRs.

  The results presented correspond to the average SEM of the performances: - of the preoperative condition (7 sessions: D-7 to D-1).

  of the postoperative condition (4 sessions preceding the injections: 40 J21,25,29,33).

  days of injections (D22, D26, D30, D34 respectively).

Wounded: n = 17 / Witnesses: n = 7.

  * p <0.05, t-matched test, significantly different from the preoperative condition ("Pre").

  # p <0.05, t-matched test, significantly different from the post-operative condition ("Post"). 45 p <0.05, ANOVA, significantly different from the control group for the same condition.

  Figure 4: Effects of PACPT-I intra-pallidal injection in a simple reaction time test.

  A. Effects on correct answers.

  B. Effects on the late responses The results presented correspond to the average SEM of the performances: - of the preoperative condition (7 sessions: D-7 to D-1) - of the postoperative condition (4 sessions which precede the injections: D21,25 , 29,33).

  - days of injections (J22, J26, J30, J34 respectively).

  Lies: n = 17 / Controls: n = 7 * p <0.05, t-matched test, significantly different from preoperative condition ("Pre").

  # p <0.05, t-matched test, significantly different from the post-operative condition ("Post").

  p <0.05, ANOVA, significantly different from the control group for the same condition.

  Figure 5: Effects of ACPT-I intra-pallidal injection on the anticipated responses in a simple reaction time test.

  The results presented correspond to the average SEM of the performances: - of the pre-operative condition (7 sessions: D-7 to D-1) - of the postoperative condition (4 sessions which precede the injections: D21,25,29,33).

  - days of injections (J22, J26, J30, J34 respectively).

  Lies: n = 17 / Controls: n = 7 * p <0.05, t-matched test, significantly different from preoperative condition ("Pre").

  # p <0.05, t-matched test, significantly different from the post-operative condition ("Post"). At p <0.05, ANOVA, significantly different from the control group for the same condition.

MATERIAL AND METHODS

- 1. Animals.

  The animals used (n = 64) are male Wistar (Charles River) rats weighing between 350 and 370 g at the time of the surgery phase. The animals were placed in a cage of two, with free access to food and water. Subsequently, food intake was rationed for the rats used in the simple reaction time test (TR - 2). Pharmaceutical substances - 6-hydroxydopamine (6-OHDA) is a specific toxin of catecholaminergic neurons. is used to induce dopaminergic neuron (DA) lesions 6-OHDA is dissolved at a concentration of 4 log / dal in a solvent comprising physiological saline (NaCl 9%) and ascorbic acid ( 0.1%).

  Haloperidol (Haldol, Janssen-Cilag, solution for injection at 5 mg / ml), a dopamine D2 receptor antagonist, is injected intraperitoneally (i.p.) at a volume of 1 ml / kg. This substance is diluted in physiological saline for a final concentration of 1 mg / kg.

  - (1S, 3R, 4S) -1-aminocyclopentane-1,3,4-tricarboxylic acid (ACPTI) is a selective agonist for mGluR4 receptors. ACPT-I was dissolved in sterile water, then in 0.1 N HCl solution, and the pH was readjusted to 7 with a few drops of 0.1 N NaOH. The concentrations of ACPT-I used are 1, 2.5 and 5 nmol / l. ACPT-1 was injected into the GP.

  - 3. Surgery 3.1. Dopaminergic lesion.

  6-OHDA is injected into the dorsal striatum, and will therefore be captured by the synaptic endings of DA neurons using the dopamine reuptake system (DAT: DA Transporter), then transported retrograde to these neurons. Once incorporated into DA neurons, this molecule causes an increase in free radical levels, which causes oxidative stress and induces degeneration of DA neurons.

  The animals were divided into two experimental groups, injured 6-OHDA (i.e. "injured" n = 28) and "control" (n = 12). The rats were injured according to the protocol described by Baunez et al (1995).

  3.2. Bilateral implantation of cannulas in globus pallidus.

  All the animals tested in this study were bilaterally cannulated at the level of globus pallidus, in order to subsequently evaluate the effects of ACPT-I, during the various behavioral tests (TR test and catalepsy). This operation occurs after the injection of 6-OHDA (or its solvent) and has been described in Almaric and Koob (1989).

  3.3. Intracerebral injection procedure After postoperative recovery and resumption of TR test performance, injections were performed in the GP in unanesthetized rats a few minutes before the test. For this purpose, stainless steel injectors 13 mm in length and 0.3 mm in external diameter are inserted into the implanted cannulas. They are connected to two 10 gl Hamilton syringes by two flexible tubes. The syringes are operated by a micropump and the injection volume is set at 0.5 gL for a flow rate of 0.166 gL / min. The animals thus receive ACPT-1 at concentrations of 0.5, 1.25 and 2.5 nmol / 0.5 μL in each GP. At the end of the injection, the system is left in place for three additional minutes to prevent any rise of the product and thus ensure its full dissemination.

- 4. Experimental devices.

4.1. Catalepsy test.

  The device used in the haloperidol-induced cataleptic test consists of a support on which a horizontal metal bar is fixed at a height of nine centimeters. 4.2. Simple Reaction Time Test.

  The experimental device used in the TR test consists of eight identical packaging cages containing a retractable lever, above which is a lamp that serves as a light stimulus. To the right of the lever is a feeder connected to an automated food dispenser. When starting the packaging cages, the lever, previously retracted and inaccessible, is put in place. Each cage is placed in a box equipped with a ventilation system that maintains a consistent background and attenuates external noise (Figure 1A). These different cages are connected to a MED PC interface (Med Associates Inc., Georgia, Vermont), which is connected to a computer that records data via the MED PC II software.

  - 5. Behavioral procedures 5.1. Catalepsy test.

  5.1.1. Principle of the haloperidol-induced cataleptic test.

  The catalepsy test is based on the fact that animals placed in an uncomfortable position immediately modify their posture in the normal state. The cataleptogenic effect of certain pharmacological compounds is manifested by the fact that the animals react only after a certain latency.

  Administration of high dose dopamine receptor antagonists, such as haloperidol, is known to induce cataleptic effects in rodents. In order to quantify the intensity of this cataleptic state (which is similar to a parkinsonian akinesia), the forelegs of the rats are positioned on a horizontal bar, and the latencies of descent of the bar are measured, up to a time limit. of 120s.

5.1.2. Experimental protocol.

  The animals are first cannulated in order to inject the ACPT-I or its solvent into the GP. After seven days of postoperative recovery, the effects of PTCA-I at 1 and 5 nmol / L are evaluated separately in two experiments spaced a week apart.

  A test phase takes place as follows: at a given time, the rats receive an i.p. injection. haloperidol or its solvent. The animals receive, 85 min later, an intra-pallidal injection of ACPTI. Immediately after the injection, which is approximately 90 min after injection of haloperidol (or its solvent), the rats are gently placed on the horizontal bar and the descent times are measured for the first time (Test 0, noted TO ).

  In order to evaluate the duration of action of the drug, the rats are then tested every ten minutes for one hour (from T10 to T60).

  5.2. Simple Reaction Time Test.

  5.2.1. Principle of the Simple Reaction Time Test.

  The test used is based on an operational conditioning with food reinforcement. Animals must learn to associate reinforcement with a specific motor sequence. The rats are trained to press a lever, wait for the appearance of a light signal and release the lever with a short TR not exceeding 600 ms to be rewarded with a 45 mg food pellet. The luminous signal, which constitutes the imperative stimulus of triggering the response, can appear according to four random and equiprobable delays of 500, 750, 1000 and 1250 ms.

  Animals can produce three types of responses: correct responses for which the lever is released with a TR less than 600 ms, and incorrect, unrewarded responses, which can be either anticipated responses, for which the rat releases the front lever. the appearance of the stimulus, and late responses, for which the animal releases the lever with a TR greater than 600 ms (FigurelB).

  Daily conditioning sessions include a total of 100 trials that can be either correct answers or delayed responses. Advance responses are accounted for separately. When the animal releases the lever too early for a given time of appearance of the light, the same delay is presented to the next test, and this until the animal achieves a correct answer or long. The maximum number of anticipated responses per session is therefore not limited. This quantization method provides an equivalent number of reaction time measurements for each stimulus onset value (25 TR measurements per time, per session and per rat). One session ends after 100 tries, or when 30 minutes have elapsed.

5.2.2. Experimental variables.

  During each session, the following variables are recorded: - The number of correct, delayed and anticipated answers described previously.

  - The reaction time (TR) corresponds to the time taken by the animal to release the lever after appearance of the light signal. The maximum allowed TR, for an answer to be considered correct, is limited to 600 ms.

5.2.3. Experimental protocol.

  After the end of the conditioning, the performances of the rats are recorded during the seven days preceding the surgery (D-7 to D-1). The measurements made during this phase constitute the pre-operative performances of the animals. After a 10 day recovery period (D0 to D9), the rats are re-tested in the TR task for a period of seven days (D10 to D16), and measurements made during this period constitute postoperative performance. in the short term (Postl). On day 18, the rats receive a first intra-pallidal injection of sterile water (solvent of ACPT-I). This first injection is intended to accustom the rats to intracerebral injections and the performances performed on D18 are not taken into account when analyzing the results. In order to evaluate the effect of treatment with ACPT-I intra-pallidal injection, in the animals of the Control group and the Lésé group, the rats then receive three injections of the drug at different concentrations (1, 2.5 and 5). nmol / L) and a solvent injection according to a "pseudo-square Latin" protocol. During this treatment phase, each animal therefore receives the solvent and the different doses of ACPT-I, and this in a different order, on the days J22, J26, J30 and J34 postoperatively. Not all combinations were feasible, only four injection orders were tested (hence the term Latin pseudo-square). Immediately after the injections, the animal performance is measured in the TR test, and compared to the performances performed the day before the injections (J21, J25, J29 and J33), which constitute a reference level. The long-term effects of the lesion are assessed during daily sessions without injection until postoperative D40. The sessions are separated into a seven-day block and are rated Post 2 and Posta. Time-based TR analyzes were conducted in 4 consecutive Pre, Postl and each injection day sessions.

- 6. Histology.

  At the end of the experiments, the animals were decapitated using a guillotine. The brains were removed rapidly, frozen in dry ice and stored at -80 ° C in a freezer. Sections of 10 am thickness are then made using a cryostat at the striatum (for the TR test rats) and the GP (for all the rats), then mounted on gelatinized glass slides. and replaced at -80 C. The blades corresponding to the GP will then be stained with cresyl violet to verify the exact position of the injection sites. In order to verify the extent of the dopaminergic lesions, the striatum sections will be labeled with 3H-mazindol (radioactive ligand of the dopamine transporters) and then revealed by an autoradiography film.

- 7. Statistical analyzes.

  The significance of the effects observed was tested using the "Statview" program. For the catalepsy test, the statistical tests used are nonparametric tests (the latency times do not follow a normal distribution, because their maximum values are limited to 120 seconds). In order to analyze the general differences between all groups, a Kruskal Wallis test is used, followed by a Mann Whitney test to compare the results between two experimental groups. To study the differences between two groups for a given time (TO to T60 post-injection of ACPT-1 or its solvent), Mann-Whitney tests were performed. In all cases, the significance level selected is 95% (p <0.05) or 99% (p <0.01). In the case of the TR test, the analyzes performed are based on analysis of variance (ANOVA) and relate on the one hand to the comparison of performances between different groups ("injured" and "control") (independent factor) and of secondly, the effects of the lesion (postoperative sessions and pre-injections) and intra-pallidal injections of ACPT-I and its solvent (dependent factor). When the repeated measures ANOVA is significant, paired t-tests or Fisher PLSD tests (posterior tests) are used to compare treatment effects within the same group. A simple ANOVA is also performed to evaluate the differences between the two groups during the same experimental condition.

RESULTS

- 1. Catalepsy test.

1.1. Effects of haloperidol.

  In comparison with the control animals ("NaCl + solvent ACPT-I") which remain on the bar for only a few seconds (descent latency less than 10 s), the latencies of the haloperidol and solvent-treated rats of the ACPT -I increase gradually at the beginning of the experiment to reach the maximum value of 120s at T20 (Figure 2A and 2B). The latency value for the animals of the haloperidol + solvent group is thus much greater than the NaCl + solvent group (Mann Whitney rank test, p <0.01 after a global "group" effect: KrusKal Wallis test, p <0.01 ).

1.2. Effects of ACPT-I.

  The descent latencies of the animals of the group "haloperidol + ACPT-I at lnmol / pL" decrease sharply compared to rats of the haloperidol + solvent group (Mann Whitney test, p <0.01), and this at all times of test following intra-pallidal injection (TO to T60) (Mann Whitney, p <0.05 for TO up to T60). However, this decrease in the descent time is greater during the first 30 minutes after the injection of ACPT-I. Indeed, from T40, the measured latency times increase, but remain lower than those of the "haloperidol + solvent" group. This recovery induced by the PCT-I at lnmol / pL is partial, since the rats of this group generally take longer to get off the bar than the control rats (NaCl + solvent) (Mann Whitney, p <0.05 from T10 to T60). However, at TO (i.e. immediately after injection of 1 mMol / L PCRT-I), the descent latencies are equivalent between these two groups.

  For the group "haloperidol + ACPT-I at 5 nmol / μL", no difference is observed with respect to the haloperidol + solvent group. In addition, the latencies for this group are higher than those of the NaCl + solvent group, and this for all the tests performed (Mann Whitney, p <0.01). For the groups "NaCl + solvent" and "NaCl + ACPT-I at lnmol / L", the latency times remain low throughout the experiments (from 5 to 10 seconds on average) and are not significantly different. On the other hand, the NaCl + ACPT-I group at 5 nmol / L shows a moderate but significant increase in latency with respect to these two groups (Mann Whitney test, p <0.01). The statistical analysis shows a significant increase in descent latency for the T20 and T50 tests compared to control (NaCl + solvent) (Mann Whitney tests, p <0.05 for T20 and T50) (Figure 1A and 1B). ).

  - 2. Simple Reaction Time Test.

  The results regarding the effects of surgery and treatment with CTPA-I, as well as the statistical analyzes presented, relate to a total of n = 35 animals.

  These rats are divided into two groups: "injured", n = 25 and "controls", n = 10.

  2.1. Preoperative performance.

  2.1.1. Correct answers, late and anticipated.

  Before the surgery phase, the animals were divided into the different groups so that their performance levels were homogeneous. During the pre-operative sessions, the rats of both groups thus have stable and equivalent performances of approximately 80-85 correct responses, 15-20 late responses and 50-60 anticipated responses on average per session (Figure 2A, B, C ).

  2.1.2. Average reaction times and motor preparation.

  In the preoperative period, mean TRs are equivalent between groups (325ms 4.7) (Figure 3A). The analysis of the TRs according to different delays of presentation of the stimulus shows that the performances are similar between groups. In addition, TR decreases progressively with increasing duration of delay (p <0.01 for each delay, tailed test after repeated measures ANOVA showing a significant "delay" effect), which shows that rats are able, at this stage of the experiment, to discriminate the different delays of appearance of the stimulus, and to use this capacity to improve their motor preparation.

  2.2. Effects of dopaminergic injury in the TR test. 2.2.1. Effects on correct, late and anticipated answers.

  In "control" animals, the number of correct and late responses does not change after surgery, compared to the preoperative level, and remains stable during the three postoperative weeks (Fisher's PLSD tests not significant). In "injured" animals, from the first postoperative sessions, the number of correct answers decreases significantly compared to the preoperative condition (p <0.01, Fisher's PLSD test after a significant "surgery" effect). This effect is lasting between Post-Periods 2 and 3. (Figure 2A). Concomitantly with this decrease in correct responses, the number of late responses significantly increased in "lesions" during the Postl period compared to Pre (p <0.01, Fisher's PLSD tests after a significant "surgery" effect ). The number of late responses is equivalent for the weeks Postl, 2 and 3 (Figure 2B). As a result, the dopaminergic neuron lesion induces a decrease in the number of correct responses and an increase in the number of late responses, in the three postoperative weeks, compared to the "control" animals (ANOVA, F (1,243) = 40,4 42.37, 25.3, p <0.01 for correct answers, F (1.243) = 40.4, 42.6, 24, 85, p <0.01 for late responses, under the conditions " If "," S2 "and" S3 ", after a significant" group "effect).

  Regarding the number of anticipated responses, no significant difference is observed between the two groups. After surgery and during the three weeks "Post", the number of anticipated responses significantly increased compared to the "Pre" period (p <0.01, Fisher's PLSD tests after a significant "surgery" effect). The number of anticipated responses decreases in week 3, compared to weeks 1 and 2 (p <0.01, Fisher's PLSD tests), but remains significantly higher than the "Pre" condition.

  2.2.2. Effects on mean TRs and on motor preparation.

  For animals in the "control" group, the mean TRs did not change after the operation, compared to the preoperative level (Fisher's PLSD test not significant) (Figure 3A). In "injured" animals, mean TRs significantly increased in the "Post1" condition compared to the "Pre" condition (p <0.01, Fisher's PLSD test after a significant interaction between "group" and "surgery" factors "). In addition, mean TRs of "injured" animals significantly increased in the "Post1" condition compared to "control" animals (single ANOVA, F (1.166) = 16.44, p <0.01) (Figure 3A).

  Time-based TR analysis showed that animals in the "control" group showed no significant difference between the Pre and Postl conditions. In the "injured" animals, in the Postl period, the mean TRs per time increase significantly with respect to the preoperative condition (p <0.01, Fisher's PLSD test) and compared to the control animals (ANOVA, F (1, 94) = 4.52, p <0.05) For animals in both groups, however, the mean TRs decrease significantly as a function of the delay in the appearance of the luminous signal in Post1 (p <0.01 for each delay, t-matched test after a significant "delay" effect), suggesting that they are still able to estimate the duration of these delays as in preoperative condition.

  2.3. Effects of ACPT-I injections in GP.

  The analysis presented concerns a total of n = 24 animals ("injured", n = 17, "controls", n = 7). The lesional effects being stable over time, only the postoperative performances corresponding to the days preceding the injections (D21, D25, D29 and D33) are retained for the continuation of the study, and are noted "Post". For the rest of the analysis, the data on the conditions "Pre" and "Post" were averaged, and compared to the data obtained after injection.

  For the animals of both groups, the effect of the order of the injections is not significant (ANOVA repeated measurements, effect "order" not significant). As a result, the data were averaged for each dose between different animals in the same group.

  2.3.1. Effects on correct and late responses.

  In "control" animals, intrapallidal injections of PTCA-I at the different doses tested, as well as solvent injection, did not significantly alter the number of correct and late responses to preoperative and pre-injection levels (FIGS. B). In addition, the performances of the animals after injection of ACPT-I or of a solvent are similar for these two types of responses. For the "injured" group, the correct and late response levels after solvent injection are significantly different from the "control" group in the same condition (ANOVA, F (1.22) = 4.35, 4.64; 0.05, after a significant "group" effect) and remain deficient with respect to performance in preoperative condition (t-matched test, p <0.01 after a significant "treatment" effect).

  In the "injured" rats, the ACPT-I considerably reduces the postoperative deficits observed during the sessions preceding the injections, and this for all the doses used. Indeed, after injection of ACPTI into the GP, the correct and late response levels are significantly different from the performances performed during the pre-injection days and during the sessions for which the rats received the solvent (t-matched tests, p <0.01 for both types of responses and for all doses after a significant "treatment" effect). Moreover, for these two types of responses, the performances after injection of ACPTI are not significantly different from the preoperative levels, and this for all the doses tested. For animals in this group and regardless of the dose used, therefore, the ACPT-I induces a total recovery of performance which is manifested by an increase in the number of correct responses and by a concomitant decrease in the number of late responses, reaching levels of similar to those of the preoperative phase. Moreover, the correct and late response levels after drug injection are similar between the different doses and between the "control" and "lesioned" animals, which tends to show that the three doses tested make it possible to restore the performance of the animals. equivalent way (Figures 5A and B).

  2.3.2. Effects on the number of anticipated responses.

  For the anticipated responses, the interindividual variability being very high (the number of anticipations is not limited in this experiment), no significant difference could be detected between the experimental groups. Unlike the other parameters, the rats of the "control" and "lesioned" groups thus react in the same way to the different doses used, and to the injections of solvent (FIG. 5).

  For these two groups, the performances measured in "Pre", "Post" and after solvent injection conditions are not different. On the other hand, the three concentrations of ACPT-I lead to a significant increase in the number of anticipated responses compared to the "Pre", "Post" and solvent conditions (t-matched test, p <0.01, after a significant "treatment" effect).

  2.3.3. Effects on mean TRs and on motor preparation.

  In the "injured" animals, the ACPT-I leads to a significant decrease of the mean TRs compared to the injection of solvent and to the days preceding the injections, and this for all the doses used (tests of tappariates, p <0, 05). In addition, the mean TRs of the "injured" after injection of ACPT-I are not significantly different from the average TRs performed by the "controls". For all the doses tested, the ACPT-I thus makes it possible to "normalize" the average TRs in the "injured" animals (FIG. 3B).

DISCUSSION

  In the cataleptic test, the results obtained show that the injection of ACPT-I at the concentration of lnmol / l partially reduces the akinesia induced by a pharmacological blocking of the dopaminergic receptors by means of haloperidol.

  In the TR test, the injection of ACPT-I into the GP is able to significantly reduce the akinesia induced by the partial bilateral lesion of the nigrostriated neurons. However, for the highest doses (2.5 and 5 nmol / μl), intra-pallidal injections of PTCA-1 lead to disturbances of the motor preparation in the injured animals and in the controls. In addition, intra- pallidal injection of this compound induces a dose-dependent increase in the number of anticipated responses for these two experimental groups.

  -1. Effects on motor parameters.

  1.1. Effect of Haloperidol and Dopaminergic Injury: Validation of Experimental Models.

  The results obtained during the catalepsy test show that the haloperidol injection results in an increase in the descent time of the bar compared with the animals that received NaCl. As evidenced by the high values of latencies of descent, this cataleptic state is manifested by a blockage in a given position, which results from a difficulty to realize a movement. In this sense, animals that have received haloperidol can be considered as akinetic.

  On the other hand, in the TR test, the results show that the intra-striatal injection of 6-OHDA resulted in deficits on an engine plane. Indeed, after retrograde lesion of the dopaminergic neurons, the number of late responses as well as the average values of the TRs increase strongly compared to the control animals (having received the solvent of the 6OHDA) and with respect to the preoperative period.

  1.2. Effects of intra-pallidal injections of ACPT-I.

  Immediately after injection into the GP, lnmol / pL CTFA-I cancels the haloperidol-induced akinesia and strongly reduces it during the first 30 minutes.

  The decrease of the beneficial effect of the ACPT-I after 30 min shows that the action of this substance is transient, which can be interpreted by a degradation of this molecule. The results obtained suggest that these effects would preferentially involve the mGlu4 receptors with a specific action at the GP level.

  The lack of effect of the 5-nmol / μL ACPT-I, as well as its slightly sedative effect in the control rats, can be explained by a non-specific high dose action.

  Indeed, in addition to its activating action of group III mGluR, the biochemical study of the pharmacological properties of the ACPT-I reveals that this compound would be able to exert an antagonistic action of the mGluRs of group I (nevertheless, the affinity of ACPT-I for these receptors is relatively low) (Acher et al., 1997). The group I mGluRs receptors being present in the GP, their blocking could thus, by decreasing the activity of the pallid neurons, lead to effects opposite to those initially expected.

  An interaction between dopamine and group III mGluR could be the basis for the differential effects of PTCA-I observed in the TR and catalepsy test. Indeed, in the TR test, intra-pallidal injections of ACPT-I significantly reduce (if not totally) the akinesia induced by the dopaminergic lesion and this at all doses tested. Thus, after injection of this substance in the "injured", the correct and late response levels as well as the average TRs are equivalent to the "control" and pre-sessional levels. These results show that the injection of a group III mGluR agonist into the GP makes it possible to effectively reduce the motor deficits observed in this rat PD model. -2. Effects on cognitive processes.

  2.1. Effects of dopaminergic injury.

  In the TR test, the lesion does not modify the ability of the animals to estimate the duration of the different delays in the appearance of the light stimulus and therefore leads to an akinetic motor deficit, without inducing cognitive disorders relative to the temporal estimation.

  However, in the postoperative period, the number of anticipated responses increases for the animals of the two experimental groups. This result shows that the modifications of this parameter are not specific to the dopaminergic lesion, since no difference between groups was observed. This increase may reflect an increase in the impulsivity level of the rats (which is a combination of motor and cognitive processes), probably secondary to the surgical stage.

  2.2. Effects of intra-pallidal injections of ACPT-I.

  The experiments carried out have shown that intra-pallidal injections of ACPT-I lead to a dose-dependent increase in the number of anticipated responses, regardless of the experimental group. Indeed, no difference could be demonstrated between the "sham" and "lesioned" animals, which implies that the lesion of the nigrostriated neurons does not modify the reactivity of the animals for this parameter.

  This effect is not therefore specific to the lesion, but to a modulation of the activity at the level of the GP. On the other hand, for the two experimental groups, the results show that the ACPT-I, at the doses of 2.5 and 5nmol / gL, causes a disturbance of the motor preparation which is manifested by a difficulty to evaluate the duration of the different delays of appearance of the light signal. If the intrapallidal injections of PTCA-I lead to deficits in the temporal estimate for the higher doses, it is possible to assume that these disturbances are at the origin of the increase in the number of expectations.

  The results obtained thus show that mGluR4 receptor agonists are capable, in intra-pallidal injection, of reducing the motor deficits observed in animal models of PM. These effects could be due to a differential reduction of gabaergic and glutamatergic transmissions from striatum and NST. In addition, these results highlight the important role GP plays in the expression of motor and cognitive symptoms of PM, and tend to show that this structure is involved in much more complex regulatory mechanisms than a simple role in relay information within the Ganglions of the Base.

BIBLIOGRAPHIC REFERENCES

  ACHER F.C., TELLIER F.J., AZERAD R., BRABET I.N., FAGNI L. & PIN J.P. (1997) Synthesis and pharmacological characterization of aminocyclopentanetricarboxylic acids: new tools to discriminate between metabotropic glutamate receptor subtypes. J Med Chem, 40, 3119-29.

  AMALRIC M. & KOOB G. F. (1989) Dorsal pallidum as a functional motor output of the corpus striatum. Brain Res, 483, 389-94.

  BAUNEZ C., NIEOULLON A. & AMALRIC M. (1995) In a rat model of parkinsonism, lesions of the subthalamic nucleus J Neurosci, 15, 6531-41.

  GAUNTLETT-GILBERT J & BROWN V. J. (1998) Reaction time 15 deficits and Parkinson's disease. Neurosci Biobehav Rev, 22, 865-81.

Claims (2)

31 CLAIMS   1. Use for making drugs for treating symptoms of akinesia in PD, compounds of formula (I) H2N \ / c o2 H R \ 5z. 2A.1., 4 3A 2 R4 - in which -R1 to R4, identical to or different from each other, represent a hydrogen atom, an alkyl radical or an aryl radical, these radicals being, if appropriate, same substituted, R1 and R2 together may further represent a bridge - (CH2) m-, where m is an integer of 1 to 5, or a bridge X representing a linear combination of m hydrocarbon groups, m being as defined hereinbelow above, and optionally having at least one hetero atom such as 0, N or S, or a bridge X representing a linear combination of p 0, N and / or S hetero atoms, where p is an integer of 1 to 3, -A1 and A2 represent -COOH, -SO3H or -PO3H2r radicals or their derivatives such as esters or amides, -Y represents a hydrocarbon chain - (CH2) -, n being zero or an integer of 1 to 5, or represents a linear combination of n hydrocarbon groups and at least one O, N or S heteroatom, or a linear combination of q hetero atoms O, N and / or S, where q is an integer of 1 to 3.   2 / The use according to claim 1, wherein said derivatives are monocyclic compounds.   3 / The use according to claim 2, wherein Y does not exist and the carbon bearing R1 and R2 are not interconnected forming one of the aforementioned bridges.   4 / The use according to claim 2, wherein the carbon bearing R1 and R2 are not interconnected forming one of the aforementioned bridges, and Y represents a group or a combination as defined above.   The use according to claim 1, wherein the compounds are bicyclic and have the formula I above wherein X or both X and Y are present and are defined as indicated above.   6 / Use according to any one of claims 1 to 5, wherein Al and A2 are identical.   7 / The use of claim 6, wherein A1 and A2 are both a carboxyl group, or the corresponding esters or amides.   8 / Use according to any one of claims 1 to 5, wherein Al and A2 differ from each other.   9 / The use according to any one of claims 1 to 8, wherein the substituents R1, R2, and / or R3 and R4 represent an alkyl or aryl radical, these radicals being optionally substituted.   10 / Use according to any one of claims 1 to 8, wherein R1 and R2 and / or R3 and R4 represent a hydrogen atom.   11 / Use according to any one of claims 1 to 10, wherein said compounds exist as achiral or chiral molecules, in the form of different diastereoisomers, optionally as racemic, where appropriate in the form of one of the enantiomers.   12 / Use of 1-amino-cyclopentane-1,3,4-tricarboxylic acid of formula HO2C CO2H ACPT I = meso-cis ACPT = (1S, 3R, 4S) for manufacturing drugs for treating the symptoms of akinesia in the MP.   13. Use according to any one of claims 1 to 12, wherein the drugs are in a form for oral administration, especially in the form of tablets, capsules, tablets, dragees, capsules, pills, drops, liposomes .   14. Use according to claim 13, characterized in that said drugs contain from 1 to 100 mg of active ingredient per unit, preferably from 2.5 to 50 mg.   15. Use according to any one of claims 1 to 12, wherein the drugs are in a form for administration by injection, especially intravenous, subcutaneous, intramuscular.   16. Use according to claim 15, characterized in that the medicaments are in the form of sterile or sterilizable solutions.   17. Use according to claim 15 or 16, characterized in that said medicaments contain from 0.5 to 50 mg of active ingredient, preferably from 1 to 30 mg.