Wang Bin, Jia Jirong, Yang Guokun, Qin Jingkai, Zhang Cong, Zhang Qiuping, Sun Caiyun, Li Wensheng
State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
Gen Comp Endocrinol. 2016 Oct 1;237:1-9. doi: 10.1016/j.ygcen.2015.10.014. Epub 2015 Oct 23.
Growth in vertebrates is mainly mediated by the growth hormone (GH)-insulin-like growth factor (IGF) axis, and somatostatin (SRIF) inhibits growth by decreasing GH release at the pituitary level and antagonizing the release and action of GHRH in the hypothalamus. However, the effects of SRIF on the regulation of growth at levels other than GH release from the pituitary gland are less well known. In the present study, we comprehensively examined the pituitary and peripheral actions of SRIF on the GH-IGF axis in grouper using a primary pituitary and hepatocyte cell culture system. Our results showed that SRIF inhibited GH release at the pituitary level, but had no influence on GH mRNA expression. Basal hepatic GH receptor 1 (GHR1), IGF-I and IGF-II mRNA levels declined over time, whereas GHR2 mRNA levels remained stable throughout the culture period. GH stimulated the hepatic expression of GHR and IGF mRNAs in a dose-dependent manner, while SRIF suppressed both basal and GH-stimulated expression of GHR and IGF mRNAs in primary cultured hepatocytes. The inhibition of GHR and IGF mRNA levels by SRIF was not attributed to the rate of mRNA degradation. To the best of our knowledge, we demonstrated the effects of SRIF on basal and GH-stimulated IGF-II mRNA levels in teleosts for the first time. These results indicate that SRIF regulates growth at the level of the pituitary and peripheral liver.
脊椎动物的生长主要由生长激素（GH）-胰岛素样生长因子（IGF）轴介导，而生长抑素（SRIF）通过降低垂体水平的GH释放以及拮抗下丘脑GHRH的释放和作用来抑制生长。然而，SRIF在垂体以外水平对生长调节的影响尚鲜为人知。在本研究中，我们使用原代垂体和肝细胞培养系统全面研究了SRIF对石斑鱼GH-IGF轴的垂体和外周作用。我们的结果表明，SRIF在垂体水平抑制GH释放，但对GH mRNA表达没有影响。基础状态下肝脏生长激素受体1（GHR1）、IGF-I和IGF-II mRNA水平随时间下降，而GHR2 mRNA水平在整个培养期间保持稳定。GH以剂量依赖的方式刺激肝脏GHR和IGF mRNA的表达，而SRIF抑制原代培养肝细胞中基础状态和GH刺激的GHR和IGF mRNA表达。SRIF对GHR和IGF mRNA水平的抑制并非归因于mRNA降解速率。据我们所知，我们首次证明了SRIF对硬骨鱼基础状态和GH刺激的IGF-II mRNA水平的影响。这些结果表明，SRIF在垂体和外周肝脏水平调节生长。
