The current proposal is an extension of our studies analyzing the disruptive effects of ethanol (ETOH) on neuroendocrine function, specifically on growth hormone-releasing factor (GHRF) and growth hormone (GH). The hypothesis to be tested is that ETOH exerts multiple neuroendocrine effects on GH in the male rat model during puberty. Animals differing in age from puberty to adult will be used. The studied will be divided into 2 phases: hypothalamis and pituitary. ETOH will be given acutely (a single intraperitoneal injection or more chronically (3 days feeding via permanent intragastric cannula). The effect of in vivo ETOH feeding on the synthesis of GHRF will be studied by measuring GHRF mRNA levels. In addition the hypothalamic GHRF content will be studied using a specific antibody for GHRF. Next, the bioactivity of GHRF will be investigated with the use of pituitary cells from normal, non-ethanol exposed animals in culture studying GH release after the addition of GHRF obtained from the hypothalami of either ethanol-fed or control animals. While the above described studies investigate in vivo ethanol effects, the secretion of GHRF in vitro will be examined both basally and when stimulated by a variety of physiologically-relevant secretagogues including clonidine (central alpha adrenergic agonist), thyroid hormone, and potassium in the presence of different doses of ETOH, ranging from 100-400 mg%. Additionally, hypothalamic-pituitary portal vessel samples will be obtained from ETOH and control animals for GHRF determination. In addition to the hypothalamic studies, the effect of feeding on the pituitary will be further characterized. GHRF receptor number and affinity on pituitary membranes obtained from ETOH and control animals will be determined. The effect of on the second messenger calcium system in GHRF- stimulated pituitary cells will be examined in an attempt to quantitate changes in intracellular free calcium-calmodulin levels. GH synthesis in the in vivo ETOH-exposed animal will be examined by measuring mRNA and correlated with pituitary GH levels by RIA and by Western Blot analysis for possible changes in molecular forms. Lastly, serum and somadomedin levels will be measured by RIA and correlated with the above results. We believe that the above described studies will physiologically dissect the exact impact of ETOH on the GHRF-GH unit in an organized and concise manner from puberty to adulthood.
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