多巴胺能药物对虎纹蛙GnRH和LH分泌活动的影响

Effects of Dopaminergic Drugs on the Secretion of Gonadotropin-releasing Hormone and Luteinizing Hormone in Rana rugulosa

利用在体注射实验和放射免疫测定法 ,研究了多巴胺能药物对性腺处于再发育期虎纹蛙的促性腺激素释放激素 (GnRH)及促黄体激素 (LH)分泌活动的影响。结果是 :多巴胺 (DA)及其激动剂阿扑吗啡 (APO)可显著降低血浆LH水平 ;而多巴胺的拮抗剂———地欧酮 (DOM)可显著增加垂体LH含量。DA对脑中cGnRH Ⅱ的合成有抑制作用 ,而DOM对其mGnRH的释放有一定的刺激作用。结果表明 :DA可在脑及垂体水平分别抑制虎纹蛙GnRH和LH的释放 ,DA对LH释放的抑制作用很可能是通过D2 受体实现的。

The effects of dopaminergic drugs on the secretion of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) were investigated by the in vivo injection of dopamine (DA), apomorphine (APO) and domperidone (DOM) into Rana rugulosa at the sexually recrudescing stage, and by radioimmunoassay. It was found that both DA and APO markedly decreased plasma LH levels, while DOM significantly elevated pituitary LH content. DA inhibited the synthesis of brain cGnRH Ⅱ, whereas DOM showed stimulatory effect on its mGnRH release. The results demonstrate that DA has inhibitory effects on the release of GnRH and LH at the brain and pituitary levels, respectively. The inhibition of DA on pituitary LH release probably acts through a D 2 receptor.