Pharmacological evidence for an involvement of group II and group III mGluRs in the presynaptic regulation of excitatory synaptic responses in the CA1 region of rat hippocampal slices.
Neuropharmacology
; 34(8): 973-82, 1995 Aug.
Article
em En
| MEDLINE
| ID: mdl-8532178
ABSTRACT
The actions of four mGluR antagonists, (+)-MCPG, MAP4, MCCG and (S)-4CPG, were evaluated against agonist-induced depressions of synaptic transmission at the Schaffer collateral-commissural pathway in rat hippocampal slices. (+)-MCPG (1 mM) reversed very effectively depressions of field EPSPs induced by (1S,3R)-ACPD and (1S,3S)-ACPD but had weak and variable effects on depressions induced by L-AP4. It had no effect on depressions induced by either (-)-baclofen or carbachol. In contrast, MAP4 (500 microM) reversed very effectively depressions induced by L-AP4 without affecting depressions induced by (1S,3S)-ACPD. MCCG (1 mM) had the opposite activity; it antagonized depressions induced by (1S,3S)-ACPD but not those induced by L-AP4. Finally, (S)-4CPG (1 mM) reversed small depressions of field EPSPs induced by high concentrations (50-100 microM) of (1S,3R)- and (1S,3S)-ACPD, but not L-AP4, whilst having no effect on large depressions induced by 10 microM (1S,3S)-ACPD in voltage-clamped cells. These results confirm and extend the effectiveness and selectivity of (+)-MCPG as an mGluR antagonist. The divergent effects of the group I antagonist, (S)-4CPG, can be explained by an indirect action on postsynaptic receptors which is manifest when high agonist concentrations are used in non-voltage-clamp experiments. The action of MCCG and MAP4 indicates that two pharmacologically-distinct mGluRs, belonging to classes II and III, can regulate synaptic transmission in the CA1 region via presynaptic mechanisms.
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Base de dados:
MEDLINE
Assunto principal:
Receptores Pré-Sinápticos
/
Receptores de Glutamato Metabotrópico
/
Aminoácidos Excitatórios
/
Antagonistas de Aminoácidos Excitatórios
/
Hipocampo
Limite:
Animals
Idioma:
En
Revista:
Neuropharmacology
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
Reino Unido