Neurogenesis and neurodegeneration in adolescent binge alcohol exposure

Adolescence is a time when many individuals begin to experiment with alcohol. Alcohol abuse and alcohol dependence, collectively termed alcohol use disorders, are diagnosed in -6% of adolescents and result in significant neuropsychological and/or cognitive deficits. As many as half of all high school students may currently drink alcohol and up to 70% of those students are binge drinkers. Considering that binge drinking is one of the factors that predicts brain damage from alcohol, understanding the impact of binge drinking on adolescent brain structure is an important public health concern. The neuroanatomical consequences of adolescent drinking are not well described, though two studies have shown hippocampal volume reductions in adolescents with alcohol use disorders. This finding confirmed behavioral and neurophysiological work in animal models that the adolescent hippocampus is targeted by alcohol. However, no one has examined whether alcohol directly produces neurodegeneration in the adolescent rat or the basic mechanism of cell or neuron reduction. The recent discovery that neural stem cells contribute to ongoing neurogenesis and to hippocampal structure suggests a novel potential mechanism of neurodegeneration alcohol-induced neurodegeneration. Thus, this proposal will test the overall hypothesis that binge alcohol exposure in the adolescent rat alters neural stem cells and neurogenesis to produce neurodegeneration. Three specific aims will address this hypothesis in an in vivo rat model of an adolescent alcohol use disorder by (1) investigating the effects of adolescent binge alcohol administration on the components of neurogenesis, (2) determining the mechanism by which alcohol intoxication inhibits neural stem cell proliferation and (3) evaluating whether changes in neurogenesis are associated with neurodegeneration (net reduction of cells) in the hippocampal dentate gyrus. Within each aim, important questions regarding the the contribution of alcohol dose or duration necessary to alter the components of neurogenesis and the contribution of cell death will be investigated. Understanding the mechanism of alcohol-induced effects on neural stem cells and dentate gyrus granule cell loss forms a solid foundation to investigate the differential sensitivity of the adolescent brain to alcohol effects and the dynamic role of both cell death and cell birth mechanisms in neurodegeneration.