[Effects of ethanol on GTP binding protein function in rat cerebral cortex: strain difference between Wistar and...

The effect of ethanol on GTP-binding protein of cortical adenylate cyclase (AC) system in the Wistar and Fischer 344 rats was examined. In both Wistar and Fischer 344 rats, ethanol (100mM) potentiated Gpp (NH) p-stimulated AC activity and decreased EC50 for Gpp (NH)p in the cerebral cortical membrane (CCM). Ethanol treatment also augmented Mn-stimulated AC activity in Wistar CCM, whereas there was no significant change in Fischer 344 CCM. IC50 calculated from the Gpp (NH)p (0.01-0.3 microM) inhibition of forskolin-stimulated AC was decreased by ethanol treatment in Wistar CCM, but this was not the case in Fischer 344 CCM. There was no appreciable change in ADP-ribosylation of Gs and Gi in CCM with pertussis or cholera toxin. These results suggest that ethanol in vitro enhances the Gi function as well as affecting the Gs function in Wistar rat cortical AC system, and the effect of ethanol on Gi protein are different in Wistar and Fischer 344 CCM.