Effect of ethanol on protein phosphorylation and dephosphorylation

Protein phosphorylation and dephosphorylation are important processes in regulating neuronal membrane function. Since ethanol is known to affect neural activity by acting on the membrane, the possibility that chronic ethanol administration results in alteration of protein kinase activity which in turn affects cellular processes is under investigation in this project. Experiments involve pair-feeding C57Bl mice with a liquid diet containing either 5% ethanol or an equal caloric amount of sucrose for 6-8 weeks. Synaptosomes were isolated from cerebral cortex and assayed for (Na,K)-ATPase and protein phosphorylation. Brain tissue was homogenized in buffer and used for assay of protein kinase C in both cytosol and membrane fractions. Chronic ethanol feeding was found to increase phosphorylation as well as the dephosphorylation activities of (Na,K)-ATPase and a 43 kD ecto-protein. In spite of large individual variances, there was a trend towards an enhanced protein kinase C activity in the membrane fraction in the chronic ethanol group. Results indicate chronic ethanol administration tends to enhance the cyclic activity of protein phosphorylation and dephosphorylation.