MOLECULAR-BIOLOGY OF INSECT NEURONAL GABA RECEPTORS

Ionotropic gamma-aminobutyric acid (GABA) receptors ave distributed th roughout the nervous systems of many insect species. As with their ver tebrate counterparts, GABA(A) receptors and GABA(C) receptors, the bin ding of GABA to ionotropic insect receptors elicits a rapid, transient opening of anion-selective ion channels which is generally inhibitory . Although insect and vertebrate GABA receptors shave a number of stru ctural and functional similarities, their pharmacology differs in seve ral aspects. Recent studies of cloned Drosophila melanogaster GABA rec eptors have clarified the contribution of particular subunits to these differences. Insect ionotropic GABA receptors are also the target of numerous insecticides and an insecticide-resistant form of a Drosophil a GABA-receptor subunit has enhanced our understanding of the structur e-function relationship of one aspect of pharmacology common to both i nsect and vertebrate GABA receptors, namely antagonism by the plant-de rived toxin picrotoxinin.