EFFECTS OF ETHANOL ON INSULIN SIGNALING IN THE BRAIN

描述(由申请人提供)：胎儿酒精谱系障碍(FASD)是美国最常见的可预防的精神发育迟滞原因。乙醇通过两种主要机制损害神经元的存活和功能：1)它抑制生存、代谢、突触形成和乙酰胆碱产生所需的胰岛素信号；2)它作为一种神经毒剂发挥作用，导致氧化应激、DNA损伤和线粒体功能障碍。乙醇对胰岛素信号的抑制是在胰岛素受体(IR)上介导的，其原因是存活信号传递的结合受损和伴随的减少。此外，逆转IR酪氨酸激酶和PI3K活性的磷酸酶的激活增加加剧了乙醇对神经元存活的抑制作用。相比之下，乙醇的神经毒性作用促进了DNA损伤，可能是由于乙醇的主要代谢物乙醛的产生和积累形成了DNA加合物。因此，宫内慢性酒精暴露会产生中枢神经系统胰岛素抵抗和氧化应激的双重状态。初步研究表明：1)CNS IR的遗传或化学耗竭导致FASD样的形态、生化和分子缺陷；2)CNS胰岛素抵抗相关的损害可以通过胰岛素增敏剂如PPAR激动剂的治疗而减轻；以及3)FASD相关的CNS异常可能持续或进展导致青少年功能缺陷。在这个相互竞争的更新应用中，在3个特定目标中提出的实验将表征慢性妊娠暴露于乙醇的长期后果，重点是青春期早期和晚期，并确定PPAR激动剂治疗预防或减少由宫内慢性乙醇暴露引起的长期中枢神经系统异常的程度和机制。目的#1将描述子宫内长期酒精暴露后早期和晚期青春期大鼠脑胰岛素抵抗的长期后果。目的#2将利用来自对照组和乙醇暴露大鼠幼鼠的原代小脑神经元培养的体外模型来表征PPAR激动剂对神经元存活和功能的影响。目的#3将利用在目的#2中获得的信息，优化PPAR激动剂治疗挽救子宫内慢性乙醇暴露对青春期早期和晚期中枢神经系统神经元存活和功能的长期不良影响的体内方法。子宫内乙醇暴露分级将用于确定PPAR激动剂的治疗效果是否随乙醇剂量的变化而变化。此外，实验将解决性别在酒精诱导的中枢神经系统异常的性质和严重程度以及对PPAR激动剂的反应性方面的作用。实验设计是翻译的，因为它利用了一种治疗策略，实际上可以应用于人类。

DESCRIPTION (provided by applicant): Fetal alcohol spectrum disorder (FASD) is the most common preventable cause of mental retardation in the USA. Ethanol impairs neuronal survival and function by two major mechanisms: 1) it inhibits insulin signaling required for viability, metabolism, synapse formation, and acetylcholine production; and 2) it functions as a neurotoxicant, causing oxidative stress, DNA damage and mitochondrial dysfunction. Ethanol inhibition of insulin signaling is mediated at the insulin receptor (IR), and caused by impaired binding and attendant reductions in the transmission of survival signals. In addition, increased activation of phosphatases that reverse IR tyrosine kinase and PI3 K activities exacerbates ethanol's inhibitory effects on neuronal survival. In contrast, the neurotoxicant effects of ethanol promote DNA damage, and are likely caused by DNA adduct formation through production and accumulation of acetaldehyde, a major metabolite of ethanol. Therefore, chronic in utero ethanol exposure produces a dual state of CNS insulin resistance and oxidative stress. Preliminary studies showed that: 1) genetic or chemical depletion of CNS IR causes FASD-like morphologic, biochemical, and molecular defects; 2) CNS insulin resistance-related impairments can be reduced by treatment with insulin-sensitizers i.e. PPAR agonists; and 3) FASD-associated CNS abnormalities may persist or progress leading to functional deficits in adolescents. In this competing renewal application, experiments proposed in 3 specific aims will characterize the long-term consequences of chronic gestational exposure to ethanol, focusing on early and late adolescence, and determine the degrees and mechanisms in which PPAR agonist treatments prevent or reduce long-term CNS abnormalities caused by chronic in utero exposure to ethanol. Aim #1 will characterize the long-term consequences of brain insulin resistance in early and late adolescent rats following chronic in utero exposure to ethanol. Aim #2 will utilize an in vitro model of primary cerebellar neuron cultures generated from control and ethanol-exposed rat pups to characterize the effects of PPAR agonists on neuronal survival and function. Aim #3 will take advantage of information gained in Aim #2 to optimize an in vivo approach for PPAR agonist therapeutic rescue of the long-term adverse effects of chronic in utero ethanol exposure in relation to CNS neuronal survival and function in early and late adolescence. Graded in utero ethanol exposures will be used to determine if the therapeutic effectiveness of PPAR agonists varies with ethanol dose. In addition, experiments will address the role of gender in relation to the nature and severity of ethanol-induced CNS abnormalities and responsiveness to PPAR agonists. The experimental design is translational because it utilizes a therapeutic strategy that realistically could be applied to humans.