ALTERATIONS IN LIPID METABOLISM IN THE NERVOUS SYSTEM BY ETHANOL

乙醇改变神经系统脂质代谢

• 批准号: 5200253
• 负责人: H-Y KIM
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/5200253
• 关键词: brain metabolism; enzyme activity; ethanol; fatty acid metabolism; fatty acylation; glioma; human subject; laboratory rat; neurons; nutrient drug interaction; phospholipase A2; phospholipids; unsaturated fatty acids

The principal objective of this study is to elucidate metabolic functions of polyunsaturated fatty acids and phospholipids in nervous tissues with particular reference to their modulation by ethanol. In neuronal membranes, docosahexaenoic acid (22:6n3) is the most abundant polyunsaturated fatty acid esterified in phospholipids. Although 22:6n3 is thought to be essential for proper neuronal and retinal function, the exact mechanisms involved in its essentiality are not clearly understood. It is possible, however, that the release of 22:6n3 may play an important role in cell signaling as has been suggested for 20:4n6 hydrolyzed by cytosolic phospholipase A2 (PLA2). In order to test this possibility, we have examined the release of polyunsaturated fatty acids, 22:6n3 and 20:4n6 from neuronal membranes using rat brain synaptosomes and C6 glioma cells. Our study indicated that 20:4n6 was preferentially hydrolyzed from brain synaptosomes by endogenous lipase activity, despite the high abundance of 22:6n3 in synaptosomal membranes. This release was not blocked by inhibitors for low molecular weight PLA2 or diacylglycerol (DG) lipase, but blocked by cytosolic PLA2 inhibitors, suggesting that PLA2 activity may be primarily involved. Synaptosomal 22:6 species appeared to be resistant to hydrolysis even after stimulation with various agonists, suggesting that 22:6n3 as a membrane component rather than as a released free fatty acid may be of more physiological importance. Similar results were obtained for primary cultures of rat hippocampal neurons. In contrast to the synaptosomal lipase activity, glioma cells and primary cultures of rat astroglia hydrolyzed 20:4n6 and 22:6n3 equally well under both stimulated and unstimulated conditions, indicating a lack of specificity. Facilitated release of 22:6n3 from glia cells may indicate that one of the supporting roles of astroglia may be providing 22:6n3 to neuronal membranes.

本研究的主要目的是阐明代谢功能 多不饱和脂肪酸和磷脂的神经组织， 特别是通过乙醇对其进行调节。 在神经元 二十二碳六烯酸（22：6n3）是最丰富的 在磷脂中酯化的多不饱和脂肪酸。 虽然22：6n3 被认为是正常的神经元和视网膜功能所必需的， 其重要性所涉及的确切机制尚不清楚。 然而，有可能22：6n3的释放可能会发挥重要的作用。 在细胞信号传导中的作用，如已建议的20：4n6水解， 胞浆磷脂酶A2（PLA2）。 为了测试这种可能性， 我们已经检测了多不饱和脂肪酸22：6N3的释放， 使用大鼠脑突触体和C6胶质瘤从神经元膜中分离20：4n6 细胞 结果表明，20：4N6在水解过程中优先发生水解， 从脑突触体的内源性脂肪酶活性，尽管高 在突触体膜上22：6n3的丰度。 这一释放不是 被低分子量PLA2或甘油二酯的抑制剂阻断 (DG)脂肪酶，但被胞质PLA2抑制剂阻断，表明 PLA2活性可能主要参与。 Synaptosomal 22：6种 似乎是耐水解，即使在刺激后， 各种激动剂，表明22：6n3作为膜组分，而不是 比释放的游离脂肪酸更具有生理学意义 重要性 对大鼠的原代培养物也获得了类似的结果。 海马神经元 与突触体脂肪酶活性相反， 神经胶质瘤细胞和大鼠星形胶质细胞的原代培养物水解20：4N6， 22：6n3在刺激和未刺激条件下同样良好， 表明缺乏特异性。 促进22：6n3从 神经胶质细胞可能表明，星形胶质细胞的支持作用之一， 为神经细胞膜提供22：6N3。