Acute and short term effects of ethanol on membrane enzymes in rat brain.

Changes in the biophysical and biochemical character of membranes brought about by ethanol have been emphasized in the underlying mechanism of alcohol toxicity. Membrane enzymes such as Na+, K+ activated ATPase, 5'-nucleotidase, and gamma-glutamyl transpeptidase were studied in cerebral cortex, cerebellum, and brain stem of rats subjected to acute and short term ethanol toxicity. Acute ethanol toxicity was induced by intraperitoneal injection of 1 ml of 7M ethanol per 100 g body weight of rat and the animals were sacrificed half an hour after the administration. Short term ethanol toxicity was induced by intraperitoneal injections of 0.5 ml (7 M ethanol) per 100 g weight of the rat for 7 days and the animals were sacrificed half an hour after the last injection. In acute ethanol toxicity the activity of Na+, K+-activated ATPase was found to decrease significantly in cerebral cortex and brain stem, while in short term alcohol toxicity, the activity was found to increase in cerebral cortex and cerebellum. The activity of gamma-glutamyl transpeptidase was found to increase in all the three regions in acute and short term ethanol toxicity. No change in the activity of 5'-nucleotidase was observed in any of the regions either in acute or in chronic ethanol toxicity. While a significant increase in the activity of adenosine deaminase was found in cerebral cortex, cerebellum, and brain stem in acute ethanol toxicity, the same was found to decrease significantly in cerebral cortex and a persistent increase in brain stem in short term ethanol toxicity. The above changes in the activities of the enzyme were discussed with reference to the well known changes in the membrane structure and consequent alteration in brain function.