Avermectin B1a: An irreversible activator of the γ-aminobutyric acid-benzodiazepine-chloride-ionophore receptor complex

Steven M. Paul, Phil Skolnick, Martin Zatz

Research output: Contribution to journalArticle

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Avermectin B1a, an antihelminthic macrocyclic lactone, has been previously shown to reduce muscle membrane resistance by stimulating γ-aminobutyric acid-mediated chloride conductance. Since the benzodiazepine receptor is coupled to a receptor for γ-aminobutyric acid and related chloride ionophore, the effects of Avermectin B1a on [3H]diazepam binding to the benzodiazepine receptor were studied. In well-washed membrane fragments from rat cerebral cortex, Avermectin B1a markedly increased the binding of [3H]diazepam to benzodiazepine receptors. This effect was qualitatively similar to that observed with either γ-aminobutyric acid or chloride ion and was partially reversed by the γ-aminobutyric acid receptor antagonist, bicuculline. In contrast to the effects of γ-aminobutyric acid and chloride, the enhanced binding of [3H]benzodiazepine elicited by Avermectin B1a was not reversed by extensive washing of the membrane preparation. Avermectin B1a appears to irreversibly modify benzodiazepine receptors at a γ-aminobutyric acid-chloride recognition site and may be valuable in biochemical studies of the regulation of benzodiazepine receptor function.

Original languageEnglish
Pages (from-to)632-638
Number of pages7
JournalTopics in Catalysis
Issue number2
StatePublished - Jan 1 1980
Externally publishedYes


  • AVM
  • Avermectin B
  • CNS
  • GABA
  • central nervous system
  • γ-aminobutyric acid

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