Effects of ethanol on the function of G proteins in rat cerebral cortex membranes

The acute effects of ethanol on the function of G protein in rat cerebral cortical membranes were examined using immunoblotting and photosensitive GTP labeling. Ethanol potentiated GppNHp-dependent activation of adenylyl cyclase and inhibition of forskolin-stimulated activity of the enzyme in corticol membranes from Wistar rats. It also enhanced guanine nucleotide binding to Gs and Gi as estimated by photoaffinity labeling. However, ethanol had no effects on the contents of Gs/alpha, Gi(1) alpha and Gi(2) alpha, and G beta subunits. While it potentiated Gi-mediated inhibition of adenylyl cyclase in Wistar rats, ethanol had no effect on the inhibitory regulation of the enzyme in the membranes from Fischer 344 rats. These results suggest that ethanol in vitro enhances both Gs and Gi functions in cerebral cortical membranes from Wistar rats and that the Gi function in the cerebral cortex may be differentially regulated by ethanol in Wistar and Fischer 344 rats.