Pace-Asciak C R, Laneuville O, Su W G, Corey E J, Gurevich N, Wu P, Carlen P L
Division of Neurosciences, Hospital for Sick Children, Toronto, ON, Canada.
Proc Natl Acad Sci U S A. 1990 Apr;87(8):3037-41. doi: 10.1073/pnas.87.8.3037.
Incubation of (8R)- and (8S)-[1-14C]hepoxilin A3 [where hepoxilin A3 is 8-hydroxy-11,12-epoxyeicosa-(5Z,9E,14Z)-trienoic acid] and glutathione with homogenates of rat brain hippocampus resulted in a product that was identified as the (8R) and (8S) diastereomers of 11-glutathionyl hepoxilin A3 by reversed-phase high performance liquid chromatographic comparison with the authentic standard made by total synthesis. Identity was further confirmed by cleavage of the isolated product with gamma-glutamyltranspeptidase to yield the corresponding cysteinylglycinyl conjugate that was identical by reversed-phase high performance liquid chromatographic analysis with the enzymic cleavage product derived from the synthetic glutathionyl conjugate. The glutathionyl and cysteinylglycinyl conjugate are referred to as hepoxilin A3-C and hepoxilin A3-D, respectively, by analogy with the established leukotriene nomenclature. Formation of hepoxilin A3-C was greatly enhanced with a concomitant decrease in formation of the epoxide hydrolase product, trioxilin A3, when the epoxide hydrolase inhibitor trichloropropene oxide was added to the incubation mixture demonstrating the presence of a dual metabolic pathway in this tissue involving hepoxilin epoxide hydrolase and glutathione S-transferase processes. Hepoxilin A3-C was tested using intracellular electrophysiological techniques on hippocampal CA1 neurons and found to be active at concentrations as low as 16 nM in causing membrane hyperpolarization, enhanced amplitude and duration of the post-spike train afterhyperpolarization, a marked increase in the inhibitory postsynaptic potential, and a decrease in the spike threshold. These findings suggest that these products in the hepoxilin pathway of arachidonic acid metabolism formed by the rat brain may function as neuromodulators.
将（8R）-和（8S）-[1-¹⁴C]肝氧素A3[其中肝氧素A3为8-羟基-11,12-环氧二十碳-（5Z,9E,14Z）-三烯酸]与谷胱甘肽和大鼠脑海马匀浆一起温育，得到一种产物，通过反相高效液相色谱与全合成制备的标准品比较，鉴定为11-谷胱甘肽基肝氧素A3的（8R）和（8S）非对映异构体。通过用γ-谷氨酰转肽酶裂解分离的产物产生相应的半胱氨酰甘氨酰缀合物，进一步证实了其同一性，该缀合物通过反相高效液相色谱分析与源自合成谷胱甘肽基缀合物的酶促裂解产物相同。参照已确立的白三烯命名法，谷胱甘肽基和半胱氨酰甘氨酰缀合物分别称为肝氧素A3-C和肝氧素A3-D。当向温育混合物中加入环氧水解酶抑制剂三氯丙烯氧化物时，肝氧素A3-C的形成大大增强，同时环氧水解酶产物三氧素A3的形成减少，这表明该组织中存在涉及肝氧素环氧水解酶和谷胱甘肽S-转移酶过程的双重代谢途径。使用细胞内电生理技术对海马CA1神经元测试肝氧素A3-C，发现其在低至16 nM的浓度下具有活性，可引起膜超极化、增强动作电位序列后超极化的幅度和持续时间、显著增加抑制性突触后电位以及降低动作电位阈值。这些发现表明，大鼠脑内花生四烯酸代谢的肝氧素途径中的这些产物可能起神经调节剂的作用。
