Acute Functional Tolerance to Ethanol Mediated by Protein Kinase Cɛ

A low level of response to ethanol is associated with increased risk of alcoholism. A major determinant of the level of response is the capacity to develop acute functional tolerance (AFT) to ethanol during a single drinking session. Mice lacking protein kinase C epsilon (PKCe) show increased signs of ethanol intoxication and reduced ethanol self-administration. Here, we report that AFT to the motor-impairing effects of ethanol is reduced in PKCe (-/-) mice when compared with wild-type littermates. In wild-type mice, in vivo ethanol exposure produced AFT that was accompanied by increased phosphorylation of PKCe and resistance of GABA A receptors to ethanol. In contrast, in PKCe (-/-) mice, GABA A receptor sensitivity to ethanol was unaltered by acute in vivo ethanol exposure. Both PKCe (-/-) and PKCe (+/+) mice developed robust chronic tolerance to ethanol, but the presence of chronic tolerance did not change ethanol preference drinking. These findings suggest that ethanol activates a PKCe signaling pathway that contributes to GABA A receptor resistance to ethanol and to AFT. AFT can be genetically dissociated from chronic tolerance, which is not regulated by PKCe and does not alter PKCe modulation of ethanol preference.