Selective changes in protein kinase C isoforms and phosphorylation of endogenous substrate proteins in rat cerebral cortex during pre- and postnatal ethanol exposure.

The effect of pre- and postnatal ethanol exposure on protein kinase C (PKC) activity, immunochemical analysis of PKC alpha, betaI, betaII, gamma, delta, epsilon, eta, and zeta by isoform-specific antibodies, and in vitro phosphorylation of endogenous substrate proteins was investigated in rat cerebral cortex. The PKC activity was increased throughout the development. However, the activity at the age of 8 days was significantly high in cytosolic and membrane fractions from ethanol-treated rats. Immunochemical analysis showed increased levels of PKC betaI and betaII at the age of 8 days, and a decrease in delta isoform at 8, 30, and 90 days of age. PKC isoforms alpha, gamma, epsilon, and eta showed no appreciable change in ethanol-treated rats. PKC zeta levels were high in the cytosolic fraction from ethanol-treated samples of 90 days age. In vitro phosphorylation of endogenous substrate proteins in the presence of Ca2+/phospholipid showed increased phosphorylation of selective membrane and cytosolic proteins with 87, 65, 50, 43, 36, and 29 kDa in ethanol-treated rats. The phosphorylation of these proteins decreased in the presence of staurosporine, which also supported PKC-mediated phosphorylation. Increased PKC activity, activation of betaI and betaII isoforms, decreased levels of delta isoform, and phosphorylation of selective substrate proteins in cerebral cortex due to alcohol exposure might be relevant in ethanol-induced central nervous system dysfunction and fetal alcohol syndrome.