促性腺激素释放激素及多巴胺对斜带石斑鱼生长激素分泌及其mRNA表达的调控(英文)

Stimulatory effects of gonadotropin-releasing hormone and dopamine on growth hormone release and growth hormone mRNA expression in Epinephelus coioides

研究斜带石斑鱼生长激素分泌及其 mRNA 表达的调控规律对于性别分化的控制、临床药物的选择,以及石斑鱼的增养殖等均具有重要的理论意义和实践意义。本文应用静态孵育系统, 采用放射免疫测定法和化学发光液相杂交实验, 研究GnRH 和 DA 对斜带石斑鱼 GH 分泌、GH mRNA 合成的调控作用。100 nmol/L sGnRH 作用斜带石斑鱼脑垂体碎片 1~24 h,明显促进GH的释放和GH mRNA的合成, 并具有时间依存性; 10 nmol/L^1 μmol/L sGnRH作用1 h 能明显促进斜带石斑鱼脑垂体释放GH,促进GH mRNA的合成, 表现出明显的剂量效应。100 nmol/L、1 μmol/L mGnRH 作用1 h 以一定的剂量依存方式促进 GH 的释放、促进 GH mRNA的合成,但 mGnRH 的效应比相应剂量的 sGnRH 的作用弱。APO 为 DA 受体的非选择性激动剂,不同剂量APO 对斜带石斑鱼脑垂体碎片的作用结果显示, 10 nmol/L^1 μmol/L APO 以剂量依存方式促进斜带石斑鱼脑垂体碎片释放GH、促进 GH mRNA的合成;1 μmol/L APO 作用 12 h 以上明显促进GH 的释放和 GH mRNA的合成,并随时间的延长而增加。与 sGnRH 对斜带石斑鱼 GH 释放、GH mRNA合成的作用相比, APO 的作用较弱。本文研究结果证实GnRH 和 DA能促进斜带石斑鱼脑垂体GH 释放和GH mRNA合成。

Gonadotropin-releasing hormone (GnRH) and dopamine (DA) can stimulate growth hormone (GH) release, but their effects on GH mRNA synthesis are controversial and deficient in fish. Orange-spotted grouper (Epinephelus coioides) is a hermaphroditic marine fish with sex reversal. Few data are available concerning the regulation of GH in grouper. In the present study, the effects of GnRH and DA on GH release and GH mRNA expression were determined using pituitary fragments of orange-spotted grouper under static culture conditions. After incubation from 1 h to 24 h, salmon GnRH (sGnRH, 100 nmol/L) stimulated the release of GH and increased the level of GH mRNA time-dependently. The minimum duration of sGnRH effect was 1 h. Both of sGnRH and mammalian GnRH (mGnRH) augmented the release of GH and the level of GH mRNA in a dose-dependent manner. The potency of sGnRH on both GH release and GH mRNA level was more pronounced than that of mGnRH. The effects of 1 μmol/L APO (Apomorphine), an agonist of D1/D2 dopamine receptors, significantly stimulated GH release and GH mRNAsynthesis after incubation for 12 h. APO stimulated GH release and GH mRNA abundance in a dose-dependent manner. These results demonstrate that both GnRH and DA directly stimulate GH release and GH mRNA expression at the pituitary level, the actions of GnRH are more potent than that of DA in orange-spotted grouper.