Pertussis toxin prevents presynaptic inhibition by kainate receptors of rat hippocampal [3H]GABA release

Abstract

Kainate receptors are ionotropic receptors, also reported to couple to Gi/Go proteins, increasing neuronal excitability through disinhibition of neuronal circuits. We directly tested in hippocampal synaptosomes if kainate receptor-mediated inhibition of GABA release involved a metabotropic action. The kainate analogue, domoate (3 [mu]M), inhibited by 24% [3H]GABA-evoked release, an effect reduced by 76% in synaptosomes pre-treated with pertussis toxin. Protein kinase C inhibition attenuated by 82% domoate-induced inhibition of GABA release whereas protein kinase C activation did not change kainate receptor binding. Thus, domoate inhibition of GABA release recruits Gi/Go proteins and a protein kinase C pathway.