Levels of dopamine and thyrotrophin-releasing hormone in hypophysial stalk blood during an oestrogen-stimulated surge of prolactin in the ovariectomized rat.
Levels of dopamine and thyrotrophin-releasing hormone in hypophysial stalk blood during an oestrogen-stimulated surge of prolactin in the ovariectomized rat.
复制标题
卵巢切除大鼠在雌激素刺激催乳素激增期间，垂体茎血中多巴胺和促甲状腺激素释放激素的水平。
作者：
W. D. de Greef;W. Klootwijk;B. Karels;T. Visser
本文观察了雌激素刺激的催乳素峰时下丘脑向垂体门静脉系统释放多巴胺和促甲状腺激素释放激素（TRH）的变化。单次注射5微克苯甲酸雌二醇导致3天后下午血浆催乳素水平可靠升高。麻醉并没有阻止今天下午激增的催乳素，虽然它的幅度只有一半的未麻醉大鼠。在此之前和期间，垂体柄血收集到甲醇中，以分析下丘脑释放的多巴胺和TRH。在这些甲醇提取物中的免疫反应性TRH作为一个单一的峰洗脱，具有相同的保留时间作为正宗的TRH反相高效液相色谱。与早晨值相比，垂体柄血中多巴胺水平下降，TRH水平升高，分别为50%和240%。这些数据表明，下丘脑多巴胺和TRH可能参与下午激增的催乳素。每日治疗对氯苯丙氨酸，5-羟色胺合成的抑制剂，减少下丘脑释放TRH的50%，但并没有阻止下午激增的催乳素和苯甲酸雌二醇诱导的TRH。
The changes in hypothalamic release of dopamine and thyrotrophin-releasing hormone (TRH) into the hypophysial portal vascular system during an oestrogen-stimulated surge of prolactin in ovariectomized rats were investigated. A single injection of 5 micrograms oestradiol benzoate resulted in a reliable increase in the plasma levels of prolactin during the afternoon 3 days later. Anaesthesia did not block this afternoon surge of prolactin, although its magnitude was only half of that of unanaesthetized rats. Before and during this surge, hypophysial stalk blood was collected into methanol to analyse the hypothalamic release of dopamine and TRH. Immunoreactive TRH in these methanolic extracts eluted as a single peak with the same retention time as authentic TRH on reverse-phase high performance liquid chromatography. In comparison to the morning values, levels of dopamine decreased and those of TRH increased in hypophysial stalk blood by 50 and 240% respectively. These data indicate that hypothalamic dopamine and TRH may be involved in the afternoon surge of prolactin. Daily treatment with parachlorophenylalanine, an inhibitor of serotonin synthesis, reduced the hypothalamic release of TRH by 50%, but did not prevent the afternoon surge of prolactin and TRH induced by oestradiol benzoate.