CHRONIC ETHANOL-CONSUMPTION ALTERS EFFECTS OF ETHANOL IN-VITRO ON BRAIN MEMBRANE-STRUCTURE OF HIGH ALCOHOL SENSITIVITY AND LOW ALCOHOL SENSITIVITY RATS

In this study, we examined if differences in initial membrane sensitiv ity to ethanol were associated with development of membrane tolerance to ethanol. High Alcohol Sensitivity (HAS) and Low Alcohol Sensitivity (LAS) rats were administered a 15% ethanol solution in water as the s ole source of fluid for 30 days. The amount of ethanol consumed per da y did not significantly differ between the HAS and LAS rats. Developme nt of membrane tolerance to in vitro effects of ethanol has been previ ously reported for bulk membrane fluidity and protein-lipid interactio n. Our data expands the understanding of ''membrane tolerance'' phenom enon to protein distribution and bilayer interdigitation. We also intr oduce genotype-dependent and genotype-independent properties of the me mbrane tolerance to ethanol. Chronic ethanol treatment produced genoty pe-dependent and genotype-independent membrane tolerance to ethanol, T he in vitro effects of ethanol on synaptic plasma membrane (SPM) prote in distribution and lipid bilayer interdigitation were abolished or de creased in the SPM of chronic ethanol-treated HAS rats, as compared wi th the SPM of HAS control rats (genotype-dependent tolerance). Protein distribution and bilayer interdigitation were not affected by ethanol in vitro in either chronic ethanol-treated or control LAS rats. Genot ype-independent tolerance to ethanol in vitro was observed for SPM ann ular and bulk bilayer fluidity in chronic ethanol-treated HAS and LAS rats. It is concluded that initial sensitivity to ethanol contributes to the development of membrane tolerance to ethanol in HAS and LAS rat s.