241459

Stimulation of benzodiazepine receptor binding by gamma-aminobutyric acid.

Article date: 1979/2/1

PubMed ID: 241459

Journal name: Proceedings of the National Academy of Sciences of the United States of America (ISSN: 0027-8424)

ABSTRACT

The effect of the neurotransmitter gamma-aminobutyric acid (GABA) on high-affinity binding of benzodiazepines to brain membranes has been investigated. GABA stimulated [3H]diazepam binding by more than 100% when extensively washed membranes from brain tissue were used. This GABA-stimulated benzodiazepine binding occurred in all brain regions examined. The stimulation was specific for GABA agonist. It was inhibited by the GABA receptor blocker bicuculline methiodide. A large number of compounds structurally closely related to GABA but without direct effect on the GABA receptor failed to enhance [3H]diazepam binding. The stimulation of benzodiazepine binding was caused by an increase in affinity; the number of binding sites remained unchanged. Half-maximal activation of [3H]diazepam binding occurred in the presence of 300 nM muscimol or 900 nM GABA. beta-Guanidinopropionic acid and imidazoleacetic acid were much weaker activators. It is suggested that the described stimulation of benzodiazepine high-affinity binding is mediated by a receptor for GABA. This site of GABA action exhibits different properties when compared to GABA receptors, as characterized by high-affinity binding of GABA agonists.

Author List: Karobath M, Sperk G

Publication Types: Journal Article

Substances mentioned in the article: Receptors, Drug; Muscimol; gamma-Aminobutyric Acid; Diazepam; Bicuculline;

Mesh terms: Animals; Bicuculline/pharmacology; Brain/metabolism; Cerebral Cortex/metabolism; Diazepam/metabolism; Kinetics; Membranes/metabolism; Muscimol/pharmacology; Rats; Receptors, Drug/drug effects; gamma-Aminobutyric Acid/pharmacology;

Citations: - 918669

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