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 α, βI, βII, γ, δ, ϵ, η, and ζ by isoform-specific antibodies, andin vitrophosphorylation 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 βI and βII at the age of 8 days, and a decrease in δ isoform at 8, 30, and 90 days of age. PKC isoforms α, γ, ϵ, and η showed no appreciable change in ethanol-treated rats. PKC ζ levels were high in the cytosolic fraction from ethanol-treated samples of 90 days age.In vitrophosphorylation 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 βI and βII isoforms, decreased levels of δ 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.