Role of arachidonate metabolites as intracellular signal transmitter in hormone action

花生四烯酸可被激素等多种激动剂从质膜磷脂中释放出来，通过环氧合酶(CO)、脂氧合酶(LO)和P-450依赖的单加氧酶途径(MO)代谢成各种二十烷类化合物。最近，一些研究人员报道，这些二十烷类化合物可能在调节各种内分泌器官的激素分泌中发挥重要作用。1)AA-5LO的中间代谢产物，如5HPETE，可能在大鼠肾上腺束状细胞侧链裂解酶将胆固醇转化为孕烯醇酮的过程中发挥重要作用。我们还发现在牛肾上腺束状细胞中存在5，15LO和P-450 MO。在牛肾上腺束状细胞中，发现P-451MO的代谢产物5，6-，8，9-，11，12-和14，15-EETs能够刺激皮质醇的分泌。2)在大鼠肝细胞中，P-450依赖的单加氧酶的存在被推测为P-450 MO(5，6-，8，9-，11，12-，14，15-EETs)的代谢产物能刺激磷酸酶活性，从而促进糖原向葡萄糖的转化。

Arachidonate can be released from plasma membrane phospholipid by various agonist such as hormones and metabolized to various eicosanoids via cyclooxygenase (CO), lipoxygenase (LO) and P-450 dependent monooxygenase pathways (MO). Recently it has been reported by several investigators that those eicosanoids may play an important role in regulation of hormone secretion in various endocrine organs.1) An intermediate metabolite of AA-5LO e.g. 5HPETE may play an important role in the conversion of cholesterol into pregnenolone by side-chain cleavage enzymes in rat adrenal fasciculata cells. We also found the existence of 5 and 15LO and P-450 MO in bovine adrenal fasciculata cells. In bovine adrenal fasciculata cells, metabolites of P-451 MO, such as 5,6-, 8,9-, 11,12- and 14,15-EETs were found to be able to stimulate cortisol secretion.2) In rat hepatocytes, existence of P-450 dependent monooxygenase were postulated the metabolites of P-450 MO (5,6-, 8,9-, 11,12-, 14,15-EETs) were found to stimulate phosphorylase activity, resulting in the enhancement of conversion of glycogen into glucose EETs were found to enhance, intracellular accumulation of Ca^<++>, suggesting that EETs may act via stimulation of Ca^<++> messenger system.