Actions of the insecticide fipronil, on dieldrin-sensitive and -resistant GABA receptors of Drosophila melanogaster

A. M. Hosie, H. A. Baylis, S. D. Buckingham, D. B. Sattelle

    Research output: Contribution to journalArticlepeer-review

    Abstract

    1. Blocking actions of the novel insecticide, fipronil, were examined on GABA responses recorded from Xenopus oocytes expressing either wild type (dieldrin-sensitive) or mutant (dieldrin-resistant) forms of the Drosophila melanogaster GABA-gated chloride channel homo-oligomer, RDL (the product of the resistance to dieldrin locus: Rdl). 2. In the case of the wild type receptor, fipronil blocked GABA-induced currents inducing both a shift to the right in the GABA dose-response curve and depressing the maximum amplitude of responses to GABA. The potency of fipronil was dependent on the GABA concentration but was unaffected by membrane potential. 3. Mutant RDL GABA-receptors, which have a naturally occurring amino acid substitution (A302→S) in the putative ion-channel lining region, conferring resistance to dieldrin and picrotoxinin, were markedly less sensitive to fipronil than the wild-type receptors. 4. Fipronil antagonism is qualitatively similar to that produced by the structurally distinct compound, picrotoxinin. As the mutation A302→S reduces the potency of both fipronil and picrotoxinin, homo-oligomeric RDL receptors should facilitate detailed studies of the molecular basis of convulsant/insecticide antagonist actions on GABA receptors.
    Original languageEnglish
    Pages (from-to)909-912
    Number of pages3
    JournalBritish Journal of Pharmacology
    Volume115
    Issue number6
    Publication statusPublished - 1995

    Keywords

    • Convulsant antagonist
    • Drosophila melanogaster
    • Fipronil
    • GABA receptor
    • Insecticide
    • Pierotoxin
    • Rdl gene

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