Canonico P L, Schettini G, Valdenegro C A, MacLeod R M
Neuroendocrinology. 1983 Sep;37(3):212-7. doi: 10.1159/000123545.
This study was designed to investigate basal and thyrotropin-releasing hormone (TRH)-stimulated prolactin release in the presence of agents that influence arachidonic acid metabolism. Agents that decrease its production by blocking phospholipase A2 activity, i.e., quinacrine and 4-bromophenacylbromide, significantly decreased prolactin secretion from anterior pituitary glands in vitro and from dispersed pituitary cells in a perifusion column. Phospholipase A2 and phorbol myristate acetate, substances that increase intracellular concentrations of arachidonic acid, markedly stimulated prolactin release by dispersed pituitary cells and by anterior pituitary glands incubated in vitro. The involvement in prolactin secretion of arachidonic acid metabolic products produced via the lipoxygenase pathway was investigated indirectly using nordihydroguaiaretic acid (NDGA), a specific inhibitor of this enzyme. NDGA progressively (dose-related) inhibited the release of prolactin in vitro and blocked the stimulating effect of 50 nM TRH on prolactin release from hemipituitary glands. Indomethacin, a specific inhibitor of the cycloxygenase pathway, had no significant effect on basal and TRH-stimulated prolactin release. The results suggest that arachidonic acid metabolism is involved in basal and TRH-stimulated prolactin secretion and that lipoxygenase pathway products are at least partially responsible for these effects.
本研究旨在探讨在存在影响花生四烯酸代谢的试剂的情况下，基础状态及促甲状腺激素释放激素（TRH）刺激的催乳素释放情况。通过阻断磷脂酶A2活性来减少其生成的试剂，即奎纳克林和4-溴苯甲酰溴，显著降低了体外垂体前叶及灌流柱中分散垂体细胞的催乳素分泌。磷脂酶A2和佛波醇肉豆蔻酸酯乙酸盐，这两种可增加细胞内花生四烯酸浓度的物质，显著刺激了分散垂体细胞及体外孵育的垂体前叶的催乳素释放。使用该酶的特异性抑制剂去甲二氢愈创木酸（NDGA）间接研究了经由脂氧合酶途径产生的花生四烯酸代谢产物在催乳素分泌中的作用。NDGA在体外逐渐（与剂量相关）抑制催乳素释放，并阻断了50 nM TRH对垂体半叶催乳素释放的刺激作用。环氧化酶途径的特异性抑制剂吲哚美辛对基础状态及TRH刺激的催乳素释放无显著影响。结果表明，花生四烯酸代谢参与基础状态及TRH刺激的催乳素分泌，且脂氧合酶途径产物至少部分介导了这些作用。
