Prenatal ethanol exposure impairs insulin and IGF signaling, which leads to cognitive/motor deficits. One main effect of developmental ethanol exposure is impaired neuronal migration. AAH is needed for neuronal migration, as it cross-talks with Notch and Wnt. Cerebellar AAH expression and function are impaired by alcohol exposure. We hypothesize that these effects are mediated by increased activation of GSK-3?, with attendant increased phosphorylation and degradation of AAH protein. We propose to: 1) characterize GSK-3?-mediated phosphorylation of AAH, and examine the effects in relation to AAH protein expression and catalytic activity, and neuronal migration; 2) delineate mechanisms of ethanol-impaired AAH expression; and 3) assess the roles of ethanol and GSK-3? mediated phosphorylation of AAH in relation to Notch signaling. Validation studies will determine the degrees to which intracerebral delivery of wildtype or mutated AAH plasmids normalize cerebellar neuronal migration in ethanol-exposed rats. Measurements will include cerebellar morphometric, motor function, assays of AAH expression and catalytic activity, and analysis of insulin/IGF, Notch, and Wnt signaling networks. We also will determine if oxidative stress and anti-oxidant treatments alter AAH expression, function, and phosphorylation. For chronic prenatal ethanol exposures, we will feed pregnant Long Evans rats isocaloric control or ethanol-containing liquid diets. For binge exposures, we will bolus treat rat pups with ethanol by i.p. injection or gavage between postnatal days 1 and 10. Subsets in each group will be treated by intracerebral injection of recombinant AAH plasmid or empty vector (control). Cerebella will be used to generate precision-cut slice cultures for in vitro analysis of insulin responsiveness. Alternatively, we will measure long-term effects of the various treatments on motor coordination, cerebellar structure, insulin/IGF-1, Notch, and Wnt signaling, and AAH expression, and sacrifice the offspring on postnatal day 35 (early adolescence) or 65 (late adolescence). We expect that inhibition of GSK-S? and enhanced expression of AAH in the developing brain will prevent long-term structural and functional abnormalities caused by prenatal or early postnatal ethanol exposures.
Prenatal alcohol exposure is the leading preventable cause of developmental cognitive-motor deficits in the USA. FASD is associated with CNS malformations, including neuronal migration disorders, which contribute to motor deficits. The proposed research will improve our understanding of how ethanol impairs neuronal migration during development and help future studies designed to prevent long-term effects of FASD.
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