Classification of GABA receptors in snail neurones.

Article date: 1988/10/18

PubMed ID: 2853063

Journal name: European journal of pharmacology (ISSN: 0014-2999)


The present study aimed to elucidate the pharmacological features of GABA receptors on identifiable neurones of Achatina fulica Férussac by testing the effects of GABA analogues, muscimol, (+/-)-baclofen, (-)-beta-hydroxy GABA and those conformationally fixed in either the extended or folded form of carbon chain, such as trans- and cis-isomers of (+/-)-2-(aminomethyl)cyclopropane-1-carboxylic acid [+/-)-cyclo-GABA-extended and (+/-)-cyclo-GABA-folded) and trans-4-amino-crotonic acid (GABA-extended). The giant neurones used were TAN, d-LPeLN, v-VNAN, v-LCDN and RPeNLN. The minimum effective concentrations (MEC) of these compounds to produce hyper- or depolarization of the membrane potentials of the neurones were determined, and the effective potency quotient (EPQ) of each compound vis-à-vis that of GABA was calculated for each neurone. The GABA receptors in these neurones were classified into the muscimol I, muscimol II and baclofen types. The muscimol I (TAN and d-LPeLN) and muscimol II (v-VNAN and v-LCDN) receptors were respectively hyperpolarized and depolarized by GABA and muscimol but were insensitive to (+/-)-baclofen. These muscimol receptors are inferred to accept GABA in an extended form of its carbon chain, since muscimol, conformationally fixed in this form from C-1 to C-4, was quite effective. Muscimol was more potent on the muscimol II receptors (MEC: 3 X 10(-7)-3 X 10(-6) M; EPQ: 30-10) than on the muscimol I type (MEC: 3 X 10(-5)-10(-4) M; EPQ: 1-0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

This document is available from: http://directlinks.cc/files/muscimol/2853063.pdf

Author List: Yongsiri A, Funase K, Takeuchi H, Shimamoto K, Ohfune Y

Publication Types: Journal Article; Research Support, Non-U.S. Gov't

Substances mentioned in the article: Receptors, GABA-A; Muscimol; gamma-Aminobutyric Acid; Baclofen;

Mesh terms: Animals; Baclofen/pharmacology; Membrane Potentials/drug effects; Muscimol/pharmacology; Neurons/metabolism; Receptors, GABA-A/drug effects; Snails/metabolism; gamma-Aminobutyric Acid/analogs & derivatives;

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