Sphingolipids in Ethanol-Induced Neuronal Apoptosis

产前酒精暴露会导致一系列称为胎儿酒精谱系障碍(FASD)的疾病。产前酒精暴露最严重的后果之一是对发育中的大脑的损害。在妊娠最后三个月和出生后几年的快速突触发生期间，乙醇会在新生啮齿动物的大脑中引发凋亡性神经退化，这与人脑发育相对应。酒精诱导的新生啮齿动物神经元丢失可能解释了FASD观察到的一些神经病理情况。然而，乙醇诱导发育中的啮齿动物脑内神经元丢失的机制尚不完全清楚。阐明这些机制将有助于FASD治疗应用的发展。这项建议旨在利用出生后第7天(P7)C57BL16小鼠的大脑来阐明乙醇诱导神经元丢失的机制，这些小鼠在急性酒精暴露时表现出强烈的神经细胞凋亡变性。我们以前的研究表明，乙醇影响脑脂代谢和信号转导通路。具体地说，我们已经显示了酒精诱导神经酰胺(一种细胞凋亡的中介)的升高，以及酒精诱导的AMP激活的蛋白激酶(AMPK)通路和磷酸肌醇3-激酶(PI3K)/Akt通路(一种生存通路)的扰动。在这一应用中，我们建议检验我们的假设，即乙醇诱导的脂质改变--特别是神经酰胺升高--在酒精诱导的AMPK和P13K1Akt通路的扰动的同时，触发或增强发育中的大脑的细胞凋亡。在目标1中，将研究乙醇对鞘脂细胞和亚细胞定位的影响，因为这将使我们深入了解这些脂类的作用。在目标2中，将寻找与乙醇诱导的神经酰胺升高有关的酶和调节剂，并检查抑制神经酰胺升高对乙醇诱导的细胞凋亡的影响。这些研究将揭示鞘磷脂在酒精诱导发育脑细胞凋亡中的作用，并将为未来FASD的治疗策略提供基础。

Prenatal alcohol exposure induces a range of disorders called fetal alcohol spectrum disorders (FASD). One of the most severe consequences of prenatal alcohol exposure is the damage to the developing brain. Ethanol triggers apoptotic neurodegeneration in the newborn rodent brain during the period of rapid synaptogenesis that corresponds to human brain development during the last trimester of pregnancy and for several years after birth. The ethanol-induced neuronal loss in newborn rodents is likely to explain some of the neuropathological conditions observed in FASD. However, mechanisms of ethanol-induced neuronal loss in the developing rodent brain are not fully understood. Elucidation of these mechanisms would contribute to the development of therapeutic applications for FASD. This proposal is aimed at elucidating the mechanisms of ethanol-induced neuronal loss using the brains of postnatal day 7 (P7) C57BLl6 mice, which show robust apoptotic neurodegeneration upon acute exposure to ethanol. Our previous studies indicate that ethanol affects brain lipid metabolism and signal transduction pathways. Specifically, we have shown ethanol-induced elevation in ceramide (a mediator of apoptosis) and ethanol-induced perturbation of the AMP-activated protein kinase (AMPK) pathway and the phosphoinositol 3-kinase (PI3K)/Akt pathway (a survival pathway). In this application, we propose to test our hypothesis that ethanol-induced lipid alteration-specifically ceramide elevationtriggers or enhances apoptosis in the developing brain in concert with ethanol-induced perturbation of the AMPK and P13K1Akt pathway. In Aim 1, changes in the cellular and subcellular localization of sphingolipids affected by ethanol will be examined because this would give insight into the roles of these lipids. In Aim 2, enzymes and regulators responsible for ethanol-induced ceramide elevation will be sought, and the effects of the inhibition of ceramide elevation on ethanol-induced apoptosis will be examined. These studies will reveal the functions of sphingolipids in ethanol-induced apoptosis in the developing brain, and will offer bases for future therapeutic strategies for FASD.