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.pdf

644 Acta Physiologica Sinica , October 25, 2004, 56 (5): 644-650 Research Paper Stimulatory effects of gonadotropin-releasing hormone and dopamine on growth hormone release and growth hormone mRNA expression in Epinephelus coioides 1,2 1 1,* RAN Xue-Qin , LI Wen-Sheng , LIN Hao-Ran 1 Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Zhongshan University, Guangzhou 510275, China; 2 School of Animal Science, Guizhou University, Guiyang 550025, China Abstract: 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 mRNA synthesis 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 dire