[Effects of ethanol on Gi protein function in rat cerebral cortex of Wistar and Fischer 344 rats: evaluation by low pH treatment].

Abstract

The present study was designed to provide further information regarding the effect of ethanol on the function of inhibitory GTP-binding (Gi) protein. To eliminate the Gs function in the regulation of adenylyl cyclase, cerebral cortex membranes from Wistar or Fischer 344 rats were pretreated at pH 4.5 ("low pH"), whereupon Gpp(NH)p-dependent inhibition of forskolin-stimulated adenylyl cyclase was examined. In the membranes from Wistar rats, ethanol (100 or 250 mM) resulted in left-shifted Gpp(NH)p inhibition curves and reduced IC50 values for Gpp(NH)p in an ethanol dose-dependent manner. In contrast, ethanol exhibited no effect on the Gpp(NH)p-dependent inhibition of the enzyme or on IC50 values for Gpp(NH)p in the membranes from Fischer 344 rats. These results are consistent with the idea that ethanol, in vitro, enhances the Gi function in the cerebral cortex of Wistar rats, and that ethanol's effect on Gi protein in the cerebral cortex is different in Wistar and Fischer 344 rats.