Actions of agonists and convulsant antagonists on a Drosophila melanogaster GABA receptor (Rdl) homo-oligomer expressed in Xenopus oocytes

Cytoplasmic injection of Xenopus oocytes with cDNA-derived RNA (cRNA) encoding a wild-type Drosophila melanogaster GABA receptor subunit (Rdl) resulted in functional expression of a GABA receptor homo-oligomer. Membrane currents recorded in response to muscimol, trans (TACA)- and cis (CACA)-4-aminocrotonic acid reversed at membrane potentials close to ECl- and were insensitive to 1.0 × 10-4 M bicuculline methiodide. An order of potency of GABA ∼ muscimol ∼ TACA > CACA > glycine was observed. Response of the expressed Drosophila Rdl receptor to GABA was reduced by t-butylbicyclophosphorothionate (TBPS), 4-n-propyl-4′-ethynylbicycloorthobenzoate (EBOB), picrotoxinin and the novel insecticide, fipronil (all at 1.0 × 10-5 M). © 1994.