- Email: [email protected]
2.431 In vivo neurochemical effects of the voltage dependent NMDA receptor antagonist CR 3394 in 6-hydroxydopamine lesioned rats
Poster Presentations: Animal models, Neurodegeneration and Neuroprotection
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2.428 VEGF and angiogenesis in an animal model of Parkinson’s disease
2.430 Effect of 1-methylxanthine, a possible A2A receptor antagonist on striatopallidal activity
M. Smeyne1° , Y. Jiao, J. Griner, H. Jang, R. Smeyne TN, USA
L.C. Jimenez Botello1° , J. Correa Basurto, O. Picazo Picazo, E. Querejeta Villagomez, M.R. Avila Costa 1 Mexico City, Mexico
1 Memphis,
Objective: Alterations in the vasculature of the substantia nigra (SN) has been shown in Parkinson’s disease (PD) patients as well as in animal models of induced parkinsonism. In rodents and humans, exercise has been shown to promote angiogenesis; and 12 weeks of exercise has been shown to protect against cell death in animal models of PD. In this study, we are examining if exercise alters angiogenesis in the SN of control and MPTPtreated exercised mice using biochemical and anatomical methods. Method: C57BL/6 and Swiss Webster mice are housed in cages with or without running wheels for 1, 2, 3 or 12 weeks. In 12 week treated mice, animals are assigned to either experimental MPTP or control groups. Seven days following MPTP, stereological measurements of vascular volume are generated using the MicroBrightfield system. VEGF levels in the SN are determined by western blotting after MPTP and at 1, 2, and 3 weeks of exercise. Results: Exercise for 1 and 2 weeks produces a significant increase in VEGF protein in the SN of both C57BL/6 and Swiss Webster mice. Three months of exercise produce no further increases in VEGF. Differences in VEGF protein between strains in standard housing plus MPTP conditions are evident, while there is no significant difference between strains in exercised mice treated with MPTP. Perfusion with vascular staining agents shows that 12 weeks of exercise results in physiological changes in the vasculature of the heart and lung. Further evaluation of SN vascular beds of exercised mice will determine whether significant differences in angiogenesis occur. Conclusion: Exercise influences VEGF levels in the SN in a mouse model of PD. Angiogenesis may provide a protective mechanism in this mouse model of PD.
Objective: To determinate 1-methylxanthine potential as A2A antagonist receptor in striatopallidal pathway Method: Docking – In order to prove if 1-methylxanthine, shows affinity for A2A adenosine receptors, a computational simulation of bind ligand-receptor (AUTODOCK3 software) was performed comparing it with caffeine. Electrophysiology – To determinate if 1-methylxanthine presents antagonic activity over striatopallidal A2A adenosine receptors, electrophysiological recordings of external globus pallidus of rats in vivo were performed. Results: Docking – Results showed that 1-methylxanthine occupies the same binding sites than caffeine and has similar affinity for this receptor (Figure 1). Electrophysiological recordings – Intrapallidal application of adenosine (100mM) produced a reduction of 50% in spontaneous pallidal activity, while application of 1-methylxanthine in same dosis increased its activity above 150% (p < 0.05, ANOVA).
2.429 Tissue transglutaminase is activated and redistributed to ER-derived granules in neuroblastoma cells treated with the PD-mimicking neurotoxin MPP+
Docking with A2A adenosine receptor.
M. Wilhelmus1° , G. Andringa, J. Bol, A.-M. van Dam, J. Hoozemans, C. Jongenelen, J. Breve, A. Boekel, B. Drukarch 1 Amsterdam, Netherlands
Conclusion: Results are encouraging, however more experiments are required to establish 1-methylxanthine efficacy as a A2A antagonist and as a possible antiparkinsonian agent.
Objective: Increased expression of tissue transglutaminase (tTG) is commonly observed in Parkinson’s disease brains (PD). However, both the role and cellular distribution of tTG in PD affected dopaminergic neurons remains to be established. Method: We analyzed expression, activity and cellular distribution of tTG in human neuroblastoma SH-SY5Y cells, with or without treatment of the well-known PD-mimicking neurotoxin MPP+. Results: Although MPP+ treatment had no effect on tTG expression level, a clear MPP+ concentration-dependent increase in tTG activity was observed using both a 5-(biotinamido)pentylamine (BAP) incorporation assay and fluorescein cadaverine histochemistry. In addition, we also observed a MPP+-induced shift in tTG immunoreactivity from an overall cytoplasmatic to a vesicle-like staining. The tTG-immunopositive vesicles demonstrated immunoreactivity for several ER specific markers, such as calreticulin, protein disulphide isomerase (PDI) and the inositol 1,4,5-trisphosphate receptor 1 (IP3R1). In addition, cell death associated markers, such as Caspase-3, were absent in cells demonstrating these tTGpositive vesicles. Our data suggest that TG-immunopositive ER-derived granules in neuronal cells might have a protective effect towards PDassociated neurotoxicity. Conclusion: We conclude that tTG activity is increased and redistributed to ER-derived granules in MPP+ treated neuroblastoma cells, probably as an attempt to initiate a tTG-dependent cell survival mechanism that counteracts a PD-specific cell death induction.
2.431 In vivo neurochemical effects of the voltage dependent NMDA receptor antagonist CR 3394 in 6-hydroxydopamine lesioned rats S. Sarre1° , M. Lanza, F. Makovec, R. Artusi, G. Caselli, Y. Michotte Belgium
1 Brussels,
Objective: Microdialysis in intact and denervated striatum of unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats was used to investigate whether CR 3394, N-[2-(3,5-dimethyl-1-adamantyl)ethyl]acetamidine, an adamantane derivative with preferential selectivity for the NR2B subunit of the NMDA receptor, has dopamine releasing properties in vivo. We also investigated whether this NMDA antagonist can potentiate the effects of L-Dopa on extracellular dopamine in these animals. Results: After systemic injection, there was no significant effect of CR 3394 on extracellular dopamine, at all doses studied (1−5 and 20 mg/kg i.p.), neither in intact nor in denervated striatum. On the other hand, striatal perfusion with 100mM of the compound elicited release of dopamine in intact, but not in denervated striatum. In denervated striatum of the 6-OHDA lesioned rats, CR 3394 (5 mg/kg) significantly enhanced the dopamine release induced by L-Dopa administration (25 mg/kg) in combination with benserazide (10 mg/kg). In particular, the onset of action of L-Dopa was potentiated. When lowering the dose of L-Dopa to a subthreshold dose of 5 mg/kg i.p., the effects of CR 3394 on the L-Dopa-induced dopamine
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Tuesday, 11 December 2007
release were lost, suggesting that a minimal dopaminergic tone supplied by L-Dopa is necessary to potentiate its own effects. Conclusion: Our data confirm the potential of the use of NR2B selective NMDA antagonists in the management of Parkinson’s disease.
2.432 Therapeutic activity of short synthetic peptides Cortagen and Livagen in Drosophila model for neurodegenerative disorders facilitated by heat shock in mutants of kynurenine pathway E. Savvateeva-Popova1° , E. Nikitina, E. Tokmacheva, A. Medvedeva, N. Kamyshev, E. Kamysheva, G. Ryzhak, V. Khavinson, P.F. Riederer 1 St. Petersburg, Russia Objective: Simple animal models facilitate express-testing of putative drugs for neurodegenerative disorders characterized by disturbances of memory, locomotion, aggregate formation and altered content of the intermediates of the kynurenine pathway. The Drosophila mutant cardinal (cd, accumulation of the generator of oxidative stress 3-hydroxykynurenine, 3-HOK) recapitulates the main disease manifestations. As shown previously, heat shock (HS) shortens the onset of severe memory and locomotor deficits in this mutant model for neurodegenerative disorders. Since therapy with short peptides Cortagen and Livagen holds much promise for correction of age-associated changes in humans, the effects of the peptides on the disease manifestations were tested in Drosophila. Method: Synthetic tetrapeptides Cortagen (Ala-Glu-Asp-Pro) and Livagen (Lys-Glu-Asp-Ala) were added to Drosophila food, either (1) during development from egg, or (2) maintenance of adults and (3) to incubation media of larval tissues in concentrations effective in humans. Learning/ memory and a state of the brain control of locomotion (monitored by sound production) were scored in 5-day old adults without and after 30-min HS given before puparium formation (variant 1, maintenance of adults on normal media) or to adults (variant 2). Rate of congophilic aggregate formation was scored without or after HS given in variant 3. Results: Having no side effects either in normal or mutant flies without or after HS, the short peptides were of differential therapeutic efficacy: both peptides were very potent in improving cognitive and locomotory abilities in variant 1, while Cortagen was only effective in variant 2. Also, Cortagen was effective in reducing congophilic aggregate formation in isolated mutant larval tissues without and after HS. Conclusion: Prolonged administration of synthetic short peptides to either developing, or adult mutants with 3-HOK excess can be of moderate or potent therapeutical value for memory and locomotor deficits and for congophilic aggregate formation in the Drosophila model for agedependent disorders.
2.433 The possibility of kynurenine metabolites binding to ionotropic glutamate receptors and to calmodulin: data on molecular modeling and Drosophila kynurenic mutants A. Zhuravlev1° , G. Zakharov, L. Sharagina, A. Popov, B. Shchegolev, P.F. Riederer, E. Savvateeva-Popova 1 St. Petersburg, Russia Objective: Kynurenine metabolites play a crucial role in neurodegenerative disease progress, which could be partly mediated by their interactions with cell receptors and signal transduction systems. Among these targets are ionotropic glutamate receptors and calmodulin (CaM). The conservative aromatic amino acids within the ligand binding pockets could determine the binding of endogenous KYNA which can involve stacking-interactions (overlap of aromatic rings p-electronic densities). Method: GAMESS 7.0 software was used for quantum chemical calculations of KYNA stacking-interactions with Phe92 of NMDA receptor NR1 subunit, His88 of NMDA receptor NR2A and Tyr61 of AMPA receptor GluR2. As the model systems we used KYNA-benzol, KYNA-imidazole
and KYNA-phenol dimers, respectively. Autodock 3.05 software was used for ligand-protein docking. The inhibition of CaM by kynurenines was evaluated using PDE1 activity test in the Drosophila kynurenine mutants. Results: Stacking-interaction binding energy is 8.4 kcal/mol (KYNAbenzol), 11.7 kcal/mol (KYNA-imidazole) and 11.0 kcal/mol (KYNAphenol). Full geometry optimization shows KYNA’s position within the ligand binding sites close to that of di-Cl-KYNA in NR1 (experiment). Docking of KYNA into subunits shows the same ligand orientation, with total energy near 8.2−8.7 kcal/mol. The kynurenine (KYN), 3-hydroxykynurenine (3HK) and KYNA docking into CaM shows the possibility of interaction between aromatic groups of these substances and hydrophobic CaM pocket. KYNA–CaM binding energy (5.1 kcal/mol) is significantly smaller than the energy of KYN and 3HK–CaM binding (6.8 kcal/mol and 7.0 kcal/mol, respectively) The PDE1 activity in the mutant cinnabar (KYNA excess) is greater compared to cardinal (3HK excess). Conclusion: Stacking-interaction makes great contribution to the KYNA-ionotropic glutamate receptors total binding energy. KYN, 3HK and KYNA could be possible antagonists of CaM (KYNA’s binding energy is the smallest one among them).
2.434 The impact of the glutamatergic manipulations on the aminoacid neurotransmitter release in pedunculopontine nucleus of hemiparkinsonian rats L. Blanco-Lezcano1° , L. Lorigados Pedre, M.E. Glez-Fraguela, N. Pavon Fuentes, L. Martinez Marti, T. Serrano 1 Havana, Cuba Objective: The pedunculopontine nucleus (PPN) is an heterogenous structure and it is reciprocally connected with the basal ganglia. The PPN receive a dopaminergic projection from SNc, a glutamatergic projection from STN and also a gabaergic innervation from output nuclei of basal ganglia. On the other hand, it sends cholinergic and glutamatergic pathways to the SNc and NST. Method: The neurotransmitter release studies were carried out employing the microdialysis cerebral technique follow up high performance liquid chromatography (HPLC) coupled fluorimetric detector. The extracellular concentrations of glutamate (GLU) and g-aminobutyric acid (GABA) were measured. The following experimental groups were organized: Group I, Non Treated rats (n = 13); Group II, 6-OHDA in SNc (n = 11); Group III, Simultaneous excitotoxic lesions in SNc STN (n = 9); Group IV, Systemic pretreatment (before and during the month of the 6-OHDA lesion) with MK-801 (5 mg/kg of weight, ip) (n = 7). Several others groups were organized as control groups. Results: The STN lesion induced a significant decrease in the GLU concentration in PPN. However, GABA concentrations only reached values in between those of the non-treated rats and the rats simultaneously lesioned in SNc STN. On the other hand, the pretreatment with MK-801 produced a significant decrease of the GLU concentration in PPN after 6-OHDA lesion. In addition, these rats exhibited the lowest rate of rotatory activity under D-Amphetamine administration and it was possible to see higher positive tyrosine hydroxylase inmunostaining in the SNc in comparison to the 6-OHDA lesioned rats. Conclusion: These results are in agreement with the current model of the basal ganglia functioning. Furthermore it suggests a very important neuroprotective role to the glutamatergic antagonist treatment at least adjusting the imbalance of the neurotransmission associated with the 6OHDA lesion at the PPN level.
S135
2.428 VEGF and angiogenesis in an animal model of Parkinson’s disease
2.430 Effect of 1-methylxanthine, a possible A2A receptor antagonist on striatopallidal activity
M. Smeyne1° , Y. Jiao, J. Griner, H. Jang, R. Smeyne TN, USA
L.C. Jimenez Botello1° , J. Correa Basurto, O. Picazo Picazo, E. Querejeta Villagomez, M.R. Avila Costa 1 Mexico City, Mexico
1 Memphis,
Objective: Alterations in the vasculature of the substantia nigra (SN) has been shown in Parkinson’s disease (PD) patients as well as in animal models of induced parkinsonism. In rodents and humans, exercise has been shown to promote angiogenesis; and 12 weeks of exercise has been shown to protect against cell death in animal models of PD. In this study, we are examining if exercise alters angiogenesis in the SN of control and MPTPtreated exercised mice using biochemical and anatomical methods. Method: C57BL/6 and Swiss Webster mice are housed in cages with or without running wheels for 1, 2, 3 or 12 weeks. In 12 week treated mice, animals are assigned to either experimental MPTP or control groups. Seven days following MPTP, stereological measurements of vascular volume are generated using the MicroBrightfield system. VEGF levels in the SN are determined by western blotting after MPTP and at 1, 2, and 3 weeks of exercise. Results: Exercise for 1 and 2 weeks produces a significant increase in VEGF protein in the SN of both C57BL/6 and Swiss Webster mice. Three months of exercise produce no further increases in VEGF. Differences in VEGF protein between strains in standard housing plus MPTP conditions are evident, while there is no significant difference between strains in exercised mice treated with MPTP. Perfusion with vascular staining agents shows that 12 weeks of exercise results in physiological changes in the vasculature of the heart and lung. Further evaluation of SN vascular beds of exercised mice will determine whether significant differences in angiogenesis occur. Conclusion: Exercise influences VEGF levels in the SN in a mouse model of PD. Angiogenesis may provide a protective mechanism in this mouse model of PD.
Objective: To determinate 1-methylxanthine potential as A2A antagonist receptor in striatopallidal pathway Method: Docking – In order to prove if 1-methylxanthine, shows affinity for A2A adenosine receptors, a computational simulation of bind ligand-receptor (AUTODOCK3 software) was performed comparing it with caffeine. Electrophysiology – To determinate if 1-methylxanthine presents antagonic activity over striatopallidal A2A adenosine receptors, electrophysiological recordings of external globus pallidus of rats in vivo were performed. Results: Docking – Results showed that 1-methylxanthine occupies the same binding sites than caffeine and has similar affinity for this receptor (Figure 1). Electrophysiological recordings – Intrapallidal application of adenosine (100mM) produced a reduction of 50% in spontaneous pallidal activity, while application of 1-methylxanthine in same dosis increased its activity above 150% (p < 0.05, ANOVA).
2.429 Tissue transglutaminase is activated and redistributed to ER-derived granules in neuroblastoma cells treated with the PD-mimicking neurotoxin MPP+
Docking with A2A adenosine receptor.
M. Wilhelmus1° , G. Andringa, J. Bol, A.-M. van Dam, J. Hoozemans, C. Jongenelen, J. Breve, A. Boekel, B. Drukarch 1 Amsterdam, Netherlands
Conclusion: Results are encouraging, however more experiments are required to establish 1-methylxanthine efficacy as a A2A antagonist and as a possible antiparkinsonian agent.
Objective: Increased expression of tissue transglutaminase (tTG) is commonly observed in Parkinson’s disease brains (PD). However, both the role and cellular distribution of tTG in PD affected dopaminergic neurons remains to be established. Method: We analyzed expression, activity and cellular distribution of tTG in human neuroblastoma SH-SY5Y cells, with or without treatment of the well-known PD-mimicking neurotoxin MPP+. Results: Although MPP+ treatment had no effect on tTG expression level, a clear MPP+ concentration-dependent increase in tTG activity was observed using both a 5-(biotinamido)pentylamine (BAP) incorporation assay and fluorescein cadaverine histochemistry. In addition, we also observed a MPP+-induced shift in tTG immunoreactivity from an overall cytoplasmatic to a vesicle-like staining. The tTG-immunopositive vesicles demonstrated immunoreactivity for several ER specific markers, such as calreticulin, protein disulphide isomerase (PDI) and the inositol 1,4,5-trisphosphate receptor 1 (IP3R1). In addition, cell death associated markers, such as Caspase-3, were absent in cells demonstrating these tTGpositive vesicles. Our data suggest that TG-immunopositive ER-derived granules in neuronal cells might have a protective effect towards PDassociated neurotoxicity. Conclusion: We conclude that tTG activity is increased and redistributed to ER-derived granules in MPP+ treated neuroblastoma cells, probably as an attempt to initiate a tTG-dependent cell survival mechanism that counteracts a PD-specific cell death induction.
2.431 In vivo neurochemical effects of the voltage dependent NMDA receptor antagonist CR 3394 in 6-hydroxydopamine lesioned rats S. Sarre1° , M. Lanza, F. Makovec, R. Artusi, G. Caselli, Y. Michotte Belgium
1 Brussels,
Objective: Microdialysis in intact and denervated striatum of unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats was used to investigate whether CR 3394, N-[2-(3,5-dimethyl-1-adamantyl)ethyl]acetamidine, an adamantane derivative with preferential selectivity for the NR2B subunit of the NMDA receptor, has dopamine releasing properties in vivo. We also investigated whether this NMDA antagonist can potentiate the effects of L-Dopa on extracellular dopamine in these animals. Results: After systemic injection, there was no significant effect of CR 3394 on extracellular dopamine, at all doses studied (1−5 and 20 mg/kg i.p.), neither in intact nor in denervated striatum. On the other hand, striatal perfusion with 100mM of the compound elicited release of dopamine in intact, but not in denervated striatum. In denervated striatum of the 6-OHDA lesioned rats, CR 3394 (5 mg/kg) significantly enhanced the dopamine release induced by L-Dopa administration (25 mg/kg) in combination with benserazide (10 mg/kg). In particular, the onset of action of L-Dopa was potentiated. When lowering the dose of L-Dopa to a subthreshold dose of 5 mg/kg i.p., the effects of CR 3394 on the L-Dopa-induced dopamine
S136
Tuesday, 11 December 2007
release were lost, suggesting that a minimal dopaminergic tone supplied by L-Dopa is necessary to potentiate its own effects. Conclusion: Our data confirm the potential of the use of NR2B selective NMDA antagonists in the management of Parkinson’s disease.
2.432 Therapeutic activity of short synthetic peptides Cortagen and Livagen in Drosophila model for neurodegenerative disorders facilitated by heat shock in mutants of kynurenine pathway E. Savvateeva-Popova1° , E. Nikitina, E. Tokmacheva, A. Medvedeva, N. Kamyshev, E. Kamysheva, G. Ryzhak, V. Khavinson, P.F. Riederer 1 St. Petersburg, Russia Objective: Simple animal models facilitate express-testing of putative drugs for neurodegenerative disorders characterized by disturbances of memory, locomotion, aggregate formation and altered content of the intermediates of the kynurenine pathway. The Drosophila mutant cardinal (cd, accumulation of the generator of oxidative stress 3-hydroxykynurenine, 3-HOK) recapitulates the main disease manifestations. As shown previously, heat shock (HS) shortens the onset of severe memory and locomotor deficits in this mutant model for neurodegenerative disorders. Since therapy with short peptides Cortagen and Livagen holds much promise for correction of age-associated changes in humans, the effects of the peptides on the disease manifestations were tested in Drosophila. Method: Synthetic tetrapeptides Cortagen (Ala-Glu-Asp-Pro) and Livagen (Lys-Glu-Asp-Ala) were added to Drosophila food, either (1) during development from egg, or (2) maintenance of adults and (3) to incubation media of larval tissues in concentrations effective in humans. Learning/ memory and a state of the brain control of locomotion (monitored by sound production) were scored in 5-day old adults without and after 30-min HS given before puparium formation (variant 1, maintenance of adults on normal media) or to adults (variant 2). Rate of congophilic aggregate formation was scored without or after HS given in variant 3. Results: Having no side effects either in normal or mutant flies without or after HS, the short peptides were of differential therapeutic efficacy: both peptides were very potent in improving cognitive and locomotory abilities in variant 1, while Cortagen was only effective in variant 2. Also, Cortagen was effective in reducing congophilic aggregate formation in isolated mutant larval tissues without and after HS. Conclusion: Prolonged administration of synthetic short peptides to either developing, or adult mutants with 3-HOK excess can be of moderate or potent therapeutical value for memory and locomotor deficits and for congophilic aggregate formation in the Drosophila model for agedependent disorders.
2.433 The possibility of kynurenine metabolites binding to ionotropic glutamate receptors and to calmodulin: data on molecular modeling and Drosophila kynurenic mutants A. Zhuravlev1° , G. Zakharov, L. Sharagina, A. Popov, B. Shchegolev, P.F. Riederer, E. Savvateeva-Popova 1 St. Petersburg, Russia Objective: Kynurenine metabolites play a crucial role in neurodegenerative disease progress, which could be partly mediated by their interactions with cell receptors and signal transduction systems. Among these targets are ionotropic glutamate receptors and calmodulin (CaM). The conservative aromatic amino acids within the ligand binding pockets could determine the binding of endogenous KYNA which can involve stacking-interactions (overlap of aromatic rings p-electronic densities). Method: GAMESS 7.0 software was used for quantum chemical calculations of KYNA stacking-interactions with Phe92 of NMDA receptor NR1 subunit, His88 of NMDA receptor NR2A and Tyr61 of AMPA receptor GluR2. As the model systems we used KYNA-benzol, KYNA-imidazole
and KYNA-phenol dimers, respectively. Autodock 3.05 software was used for ligand-protein docking. The inhibition of CaM by kynurenines was evaluated using PDE1 activity test in the Drosophila kynurenine mutants. Results: Stacking-interaction binding energy is 8.4 kcal/mol (KYNAbenzol), 11.7 kcal/mol (KYNA-imidazole) and 11.0 kcal/mol (KYNAphenol). Full geometry optimization shows KYNA’s position within the ligand binding sites close to that of di-Cl-KYNA in NR1 (experiment). Docking of KYNA into subunits shows the same ligand orientation, with total energy near 8.2−8.7 kcal/mol. The kynurenine (KYN), 3-hydroxykynurenine (3HK) and KYNA docking into CaM shows the possibility of interaction between aromatic groups of these substances and hydrophobic CaM pocket. KYNA–CaM binding energy (5.1 kcal/mol) is significantly smaller than the energy of KYN and 3HK–CaM binding (6.8 kcal/mol and 7.0 kcal/mol, respectively) The PDE1 activity in the mutant cinnabar (KYNA excess) is greater compared to cardinal (3HK excess). Conclusion: Stacking-interaction makes great contribution to the KYNA-ionotropic glutamate receptors total binding energy. KYN, 3HK and KYNA could be possible antagonists of CaM (KYNA’s binding energy is the smallest one among them).
2.434 The impact of the glutamatergic manipulations on the aminoacid neurotransmitter release in pedunculopontine nucleus of hemiparkinsonian rats L. Blanco-Lezcano1° , L. Lorigados Pedre, M.E. Glez-Fraguela, N. Pavon Fuentes, L. Martinez Marti, T. Serrano 1 Havana, Cuba Objective: The pedunculopontine nucleus (PPN) is an heterogenous structure and it is reciprocally connected with the basal ganglia. The PPN receive a dopaminergic projection from SNc, a glutamatergic projection from STN and also a gabaergic innervation from output nuclei of basal ganglia. On the other hand, it sends cholinergic and glutamatergic pathways to the SNc and NST. Method: The neurotransmitter release studies were carried out employing the microdialysis cerebral technique follow up high performance liquid chromatography (HPLC) coupled fluorimetric detector. The extracellular concentrations of glutamate (GLU) and g-aminobutyric acid (GABA) were measured. The following experimental groups were organized: Group I, Non Treated rats (n = 13); Group II, 6-OHDA in SNc (n = 11); Group III, Simultaneous excitotoxic lesions in SNc STN (n = 9); Group IV, Systemic pretreatment (before and during the month of the 6-OHDA lesion) with MK-801 (5 mg/kg of weight, ip) (n = 7). Several others groups were organized as control groups. Results: The STN lesion induced a significant decrease in the GLU concentration in PPN. However, GABA concentrations only reached values in between those of the non-treated rats and the rats simultaneously lesioned in SNc STN. On the other hand, the pretreatment with MK-801 produced a significant decrease of the GLU concentration in PPN after 6-OHDA lesion. In addition, these rats exhibited the lowest rate of rotatory activity under D-Amphetamine administration and it was possible to see higher positive tyrosine hydroxylase inmunostaining in the SNc in comparison to the 6-OHDA lesioned rats. Conclusion: These results are in agreement with the current model of the basal ganglia functioning. Furthermore it suggests a very important neuroprotective role to the glutamatergic antagonist treatment at least adjusting the imbalance of the neurotransmission associated with the 6OHDA lesion at the PPN level.