Exposure to alcohol alters the activity of the hypothalamic-pituitary-adrenal (HPA) axis. Work carried out inour laboratory as well as other's indicates that prenatal alcohol exposure augments HPA axis activityin matureoffspring, while animals chronically exposed to the drug for the first time in adulthood display blunted HPAaxis responses. The purpose of this proposal is to investigate some of the mechanisms responsible for theseeffects. First, we will focus on nitric oxide (NO), a gaseous neurotransmitterthat, as we recently reported,significantly stimulates levels of corticotropin releasing factor (CRF) and vasopressin (VP) in thehypothalamus. Specifically, we will test the hypothesis that prenatal alcohol alters (a) hypothalamic levels ofNO and NO synthase (NOS), the enzyme responsible for NO formation, (b) the CRF and/or VP neuronalresponse to NO donors, and (c) the physiological role played by NO, which will be studied with NOSantagonists (Specific Aim 1). Second, we will test the hypothesis that alcohol-induced increases inhypothalamic CRF levels, through activation of a hypothalamic feed forward mechanism previously reportedby our laboratory, participates in the hyperactive HPA axis that is the hallmark of prenatal alcohol (SpecificAim 2). At present, there is no information regarding the effect of prenatal alcohol exposure on the HPA axisof murine offspring. As a first step, we will therefore develop a murine model of prenatal alcohol treatmentand investigate HPA axis responses in wild-type mice born to dams exposed to alcohol during gestation. Theseexperiments will rely on an automated system that was recently developed in our laboratory, and that allows usto deliver intermittent amounts of alcohol vapors that are customized for each animal. Once the parameters ofthis new model are established, we will investigate the role of alcohol-induced changes in CRF levels, byexposing to alcohol vapors pregnant wild-type mice and mice lacking the gene for CRF receptors type 1 or 2,and comparing the HPA axis of their offspring. The final part of our proposal will focus on the hypothesisthatlong-term alcohol vapor treatment of adult rats decreases hypothalamic NO production, thereby contributing tothe blunted HPA axis activity that characterizes these animal (Specific Aim 3). All the proposed experimentsrely on cutting-edge methodology that was developed in our laboratory, as well as on recent concepts of brainregulation by NO. These studies will provide important information regarding effects of alcohol that are welldocumented in animal models as well as in humans, but for which mechanisms remain poorly understood.
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