半胱胺对斜带石斑鱼(Epinephelus coioides)生长激素及其受体mRNA水平的影响

EFFECTS OF CYSTEAMINE ON mRNA LEVELS OF GROWTH HORMONE AND ITS RECEPTORS IN ORANGE-SPOTTED GROUPER EPINEPHELUS COIOIDES

以海水硬骨鱼类斜带石斑鱼为研究对象,通过投喂和腹腔注射半胱胺盐酸盐(CSH),研究半胱胺对斜带石斑鱼生长激素(GH)及其受体(GHR)mRNA水平的影响,以初步揭示半胱胺促进斜带石斑鱼生长的作用机理。结果表明,长期投喂CSH可以显著提高斜带石斑鱼的相对体重增长率。投喂和腹腔注射不同剂量的CSH均能明显促进斜带石斑鱼脑垂体GHmRNA水平及肝脏2种gGHRmRNA水平,且促进效果与CSH浓度呈剂量依存关系。本研究还就CSH对斜带石斑鱼2种不同类型GHR作用的剂量效应和时间效应进行了初步探讨。通过注射不同剂量CSH发现,低剂量CSH(20μg/g体重)只可以引起gGHR2mRNA水平的显著提高。中剂量CSH(50μg/g体重)可同时显著提高gGHR1和gGHR2mRNA水平,但gGHR2水平明显高于gGHR1水平;通过单独注射50μg/g体重CSH溶液发现,注射后2h,2种gGHRmRNA水平均有显著升高,其中gGHR2水平明显高于gGHR1。注射后6h,gGHR2mRNA水平率先达到最高值。注射后12h,gGHR1mRNA水平达到最大值。由此可以推测gGHR2对于CSH所引起刺激的剂量敏感性及时间敏感性均高于gGHR1。

In present research, we found that cysteamine hydrochloride （CSH） administrated in diet could significantly enhance growth of orange-spotted grouper Epinephelus coioides. Both CSH administrated through diet and injection could enhance the levels of growth hormone （GH） mRNA and two types of growth hormone receptors （GHR） mRNA in or- ange-spotted grouper in a dose-dependent manner. In addition, changes of the levels of two GHRs mRNA induced by the injection of CSH at different doses/hours were investigated. Injection of CSH at 20 gg/g b.w. could only enhance gGHR2 mRNA level significantly; in contrast the medium dose of CSH （50gg/g b.w.） could significantly enhance two types of GHR mRNA levels. Furthermore, two hours after injection of CSH at 50gg/g b.w., the levels of two GHR mRNA were increased significantly and gGHR2 mRNA level was much higher than that of gGHR1, gGHR2 mRNA level reached maximum 6 hours after injection, while gGHR1 got to the peak value 12 hours after injection. So, gGHR2 seemed more sensitive to the stimulation induced by the injection of CSH.