Shivachar A C, Willoughby K A, Ellis E F
Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0613, USA.
J Neurochem. 1995 Jul;65(1):338-46. doi: 10.1046/j.1471-4159.1995.65010338.x.
Our previous studies have shown that 14,15-epoxyeicosatrienoic acid (14,15-EET) is a major product of arachidonic acid metabolism in astrocytes. The purpose of this study was to investigate cellular regulation of 14,15-EET incorporation, distribution, and metabolism in primary cultures of rat brain cortical astrocytes. Incorporation of 14,15-EET into astrocytes was lower (93,390 +/- 11,121 dpm/5 x 10(6) cells) than incorporation of 8,9-EET (226,500 +/- 5,567 dpm/5 x 10(6) cells) and arachidonic acid (321,600 +/- 1,200 dpm/5 x 10(6) cells). 14,15-EET was distributed in the order neutral lipids and free fatty acids (solvent front) >> phosphatidylcholine (PC) > phosphatidylinositol (PI) > phosphatidylethanolamine. In contrast, 8,9-EET and arachidonic acid were exclusively incorporated into PC. During incubation, astroglial epoxide hydrolase selectively metabolized 14,15-EET, but not 8,9-EET, to its vic-diol. Although 4-phenylchalcone oxide, a potent inhibitor of epoxide hydrolase, completely inhibited 14,15-EET metabolism, a large amount of cell-incorporated radioactivity remained as free 14,15-EET. Long-term exposure of astrocytes to 4 beta-phorbol 12-myristate 13-acetate (4 beta-PMA) resulted in a time-dependent incorporation of 14,15-EET into PI but not in control cells exposed to 4 alpha-phorbol 12,13-didecanoate. PKC down-regulation completely inhibited epoxide hydrolase metabolism of 14,15-EET. Following recovery of down-regulated PKC, 1 week after treatment with 4 beta-PMA, astrocytes regained their normal pattern of low incorporation of 14,15-EET. Protein kinase C (PKC) inhibition by staurosporine enhanced 14,15-EET incorporation without affecting its metabolism to 14,15-dihydroxyeicosatrienoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
我们之前的研究表明，14,15-环氧二十碳三烯酸（14,15-EET）是星形胶质细胞中花生四烯酸代谢的主要产物。本研究的目的是调查大鼠脑皮质星形胶质细胞原代培养物中14,15-EET掺入、分布和代谢的细胞调控。14,15-EET掺入星形胶质细胞的量（93,390±11,121 dpm/5×10⁶个细胞）低于8,9-EET（226,500±5,567 dpm/5×10⁶个细胞）和花生四烯酸（321,600±1,200 dpm/5×10⁶个细胞）。14,15-EET按中性脂质和游离脂肪酸（溶剂前沿）>>磷脂酰胆碱（PC）>磷脂酰肌醇（PI）>磷脂酰乙醇胺的顺序分布。相比之下，8,9-EET和花生四烯酸仅掺入PC中。在孵育过程中，星形胶质细胞环氧水解酶选择性地将14,15-EET代谢为其邻二醇，但不代谢8,9-EET。尽管环氧水解酶的强效抑制剂4-苯基查耳酮氧化物完全抑制了14,15-EET的代谢，但大量细胞掺入的放射性仍以游离的14,15-EET形式存在。星形胶质细胞长期暴露于4β-佛波醇12-肉豆蔻酸酯13-乙酸酯（4β-PMA）导致14,15-EET随时间依赖性地掺入PI中，但暴露于4α-佛波醇12,13-十二烷酸酯的对照细胞中则没有。蛋白激酶C（PKC）下调完全抑制了14,15-EET的环氧水解酶代谢。在用4β-PMA处理1周后下调的PKC恢复后，星形胶质细胞恢复了其低掺入14,15-EET 的正常模式。星形孢菌素对蛋白激酶C（PKC）的抑制增强了14,15-EET的掺入，而不影响其代谢为14,15-二羟基二十碳三烯酸。（摘要截短于250字）
