The overall goal of this proposal is to elucidate the mechanisms by which prenatal exposure to moderate doses of alcohol results in long-lasting impairment of enrichment-mediated adult hippocampal neurogenesis, and to link this deficit with impairment of hippocampal-dependent learning in our mouse model of fetal alcohol spectrum disorder (FASD). FASD mice display impaired cognitive ability in hippocampal-dependent learning tasks and show signs of depressive disorder. FASD mice also display persistent deficits in adult hippocampal neurogenesis, which become apparent when the mice are behaviorally challenged by exposure to enriched environment. In this proposal, experiments are designed to determine whether the mechanisms underlying the FASD phenotype include impaired neuronal differentiation and maturation of neural stem cells in adult hippocampus, and diminished incorporation of adult-generated dentate granule cells into spatial memory networks. To test this, we will utilize a novel conditional and inducible nestin- CreERT2:YFP transgenic mouse which allows non-invasive labeling of large numbers of adult neural stem cells and their progeny. FASD and Sacc (control) mice will be generated in the nestin-CreERT2:YFP strain and utilized to address the following Specific Aims.
Specific Aim 1 To determine whether prenatal ethanol exposure impairs neuronal differentiation and maturation of adult hippocampal neural stem cells. The nestin-CreERT2:YFP strain will be used to fate map and characterize neuronal differentiation of neural stem cells in adult hippocampus of FASD and Sacc (control) mice in vivo (SA1.1) and following isolation of adult NSCs in vitro (SA1.2).
Specific Aim 2 : To determine whether prenatal exposure to alcohol impairs synaptic maturation and plasticity of adult-born dentate granule cells (DGCs). Tamoxifen will be used to birthdate and YFP label newborn DGCs for electrophysiological recordings in adult hippocampal slice preparations from FASD and Sacc nestin-CreERT2:YFP mice. Using this approach, we will test the hypotheses that prenatal alcohol exposure disrupts the maturation of GABA- and glutamate-mediated currents (SA2.1) and attenuates LTP plasticity in adult born DGCs (SA2.2).
Specific Aim 3 : To determine whether prenatal ethanol exposure impairs the ability of newly- generated DGCs to preferentially incorporate into spatial memory networks. We will determine whether preferential activation of newborn neurons is attenuated in adult hippocampus of FASD mice during recall of a spatial memory task, as assessed by immediate early gene (c-fos) expression nestin-CreERT2:YFP mice.
This project will investigate how prenatal alcohol exposure acts to inhibit the production of new neurons within a region of the adult brain known as the hippocampus. The production of new neurons in this brain region is thought to be involved in the formation of certain types of memories. Understanding how prenatal alcohol exposure impacts the neurogenesis in the adult hippocampus may shed light on the mechanism underlying cognitive defects in Fetal Alcohol Spectrum Disorder, a prevalent condition that is observed in children whose mothers consumed moderate amounts of alcohol throughout pregnancy.
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