Continuous ethanol exposure inhibits agonist-stimulated phosphorylation of p70S6 kinase and ribosomal S6 protein in cultured rat astrocytes

The effects of ethanol exposure on agonist-stimulated phosphorylation of p70S6 kinase and ribosomal S6 protein were determined in confluent astrocyte monolayers. Basal phosphorylation of p70S6 kinase and S6 protein was either unaffected or reduced, respectively, after exposure to 50 mM ethanol for 4 days. The abilities of norepinephrine, carbachol and epidermal growth factor to phosphorylate these proteins were significantly decreased after ethanol exposure. In contrast, ethanol exposure had no effect on the protein expression of either p70S6 kinase or S6 protein. Our data suggest that continuous ethanol exposure results in a generalized decrease in agonist-activation of the p70S6 pathway.