Neurochemical effects of long-term ingestion of ethanol by Sinclair (S-1) swine.

Sinclair (S-1) miniature swine were given access to a mixture of ethanol and beer for three years. Control swine were fed an isocaloric diet with corn starch substituted for ethanol. Both groups had free access to tap water. The alcohol group consumed about 4 g ethanol/kg/day (about 50% of their caloric intake) resulting in plasma ethanol concentrations of about 100 mg/dl. Brain membranes were prepared for analysis of neurotransmitter receptor binding, membrane lipid composition and physical properties. Receptor studies demonstrated an increase in the binding of 3H-GABA to cortical and cerebellar membranes from the alcoholic pigs as compared to control. Binding of 3H-ligands to muscarine cholinergic, beta-adrenergic, alpha-adrenergic, dopamine and benzodiazepine receptors was not changed by chronic ethanol ingestion. These results are similar to those obtained in studies of human alcoholics by other investigators. The cholesterol content of myelin and synaptic plasma membranes was not altered by ethanol consumption. The fluorescence polarization of diphenylhexatriene, a measure of membrane order, did not detect any differences in the membranes from control or alcohol-treated swine either before or after in vitro exposure to ethanol. These results are different from those reported for rodents after short-term ethanol treatments and emphasize the importance of evaluating different models of experimental alcoholism.