Ching M, Lin Y C
Department of Veterinary Anatomy, College of Veterinary Medicine, Ohio State University, Columbus 43210.
Alcohol. 1994 Mar-Apr;11(2):105-12. doi: 10.1016/0741-8329(94)90051-5.
Ethanol (ETOH) administered acutely to castrate male rats caused a decline in pituitary luteinizing hormone (LH) and prolactin (PRL) secretion. This was associated with an elevation in hypothalamic and median eminence stores of dopamine (DA) that was related to the dose of alcohol given. Pituitary stalk transection (PST) resulted in a significant rise in plasma PRL levels compared to sham control animals, which suggests that DA in the hypophysial portal blood exerted an inhibitory influence on pituitary PRL secretion. The DA agonist bromocriptine failed to alter mean plasma LH levels in stalk-transected rats. The ETOH-treated castrated rats showed a significant rise in circulating PRL after injection of the DA receptor antagonist haloperidol metabolite II (HAL), but the administration of the DA receptor agonist R(-)-apomorphine HCL (APO) caused plasma PRL to decline to near undetectable levels. Plasma LH levels remained unchanged in the HAL- and APO-treated rats and were similar to those of sham controls. These results suggest that lactotroph DA receptors were still functional. Thus our previous finding of ETOH-induced reduction on LH secretion may be attributable to an inhibitory effect by DA on the luteinizing hormone-releasing hormone (LHRH) peptidergic neurons rather than a direct inhibition by DA on the pituitary gonadotroph.
急性给予去势雄性大鼠乙醇（ETOH）会导致垂体促黄体生成素（LH）和催乳素（PRL）分泌减少。这与下丘脑和正中隆起多巴胺（DA）储存量增加有关，而这种增加与给予的酒精剂量相关。与假手术对照动物相比，垂体柄横断术（PST）导致血浆PRL水平显著升高，这表明垂体门脉血中的DA对垂体PRL分泌具有抑制作用。DA激动剂溴隐亭未能改变垂体柄横断大鼠的平均血浆LH水平。给予DA受体拮抗剂氟哌啶醇代谢物II（HAL）后，经ETOH处理的去势大鼠循环PRL显著升高，但给予DA受体激动剂R(-)-阿扑吗啡盐酸盐（APO）导致血浆PRL降至几乎检测不到的水平。HAL和APO处理的大鼠血浆LH水平保持不变，与假手术对照组相似。这些结果表明催乳素细胞的DA受体仍然具有功能。因此，我们之前发现ETOH诱导LH分泌减少可能归因于DA对促黄体生成素释放激素（LHRH）肽能神经元的抑制作用，而不是DA对垂体促性腺激素细胞的直接抑制作用。
