The Graduate Program in Aquaculture, The Graduate School, Kasetsart University, Bangkok 10900, Thailand.
Gen Comp Endocrinol. 2012 Jun 1;177(2):278-92. doi: 10.1016/j.ygcen.2012.03.008. Epub 2012 Mar 27.
The influence of 17α-methyltestosterone (MT) on growth responses, biological parameters and the expression of genes involved in the GH-IGF pathway of the hypothalamic-pituitary-liver-gonadal axis were investigated in female, male, and sex-reversed Nile tilapia to evaluate the relationship between sex and MT-induced changes in these parameters. Female fish had a lower growth rate than male and sex-reversed fish, and MT increased growth performance and duodenal villi in females. Most but not all biological parameters of sex-reversed fish were similar to those of male fish. Male fish had higher red blood cell counts and hemoglobin levels than female and sex-reversed fish, suggesting that these hematological indices reflect a higher metabolic rate in male fish. Greater blood triglyceride levels indicated the vitellogenin process in female fish. MT increased the alternative complement activity in female fish (P<0.05). Sex and MT had no significant effects on the hypothalamic mRNAs of GHRH and PACAP. Although not statistically significant, females tended to have higher GH mRNA levels than male and sex-reversed fish. Additionally, MT tended to decrease and increase GH mRNA levels in female and male fish, respectively. There were significant differences among sexes in the expression of GHR, and IGF mRNAs at the peripheral level in the liver and gonads. Females had lower hepatic GHRs and higher ovarian GHRs than male and sex-reversed fish. While the mRNA levels of IGF-1 were lower in the ovary, the levels of IGF-2 were higher compared with those in testes. A significant correlation between GHRs and IGFs was demonstrated in the liver and gonad (except for IGF-1). Multiple regression analysis showed a significant relationship between GH mRNA and both GHRs and IGFs in the liver and gonad. MT exerted androgenic and, to some extent, estrogenic effects on several physiological parameters and GH-IGF action.
研究了 17α-甲基睾丸酮（MT）对雌、雄和性反转尼罗罗非鱼下丘脑-垂体-肝-性腺轴生长反应、生物学参数和 GH-IGF 途径相关基因表达的影响，以评估性别与 MT 诱导这些参数变化之间的关系。雌鱼的生长速度低于雄鱼和性反转鱼，MT 提高了雌鱼的生长性能和十二指肠绒毛。性反转鱼的大多数生物学参数与雄鱼相似，但并非全部。雄鱼的红细胞计数和血红蛋白水平高于雌鱼和性反转鱼，表明这些血液学指标反映了雄鱼更高的代谢率。较高的血液甘油三酯水平表明雌鱼正在进行卵黄蛋白原过程。MT 增加了雌鱼的替代补体活性（P<0.05）。性别和 MT 对下丘脑 GHRH 和 PACAP 的 mRNA 没有显著影响。尽管没有统计学意义，但雌鱼的 GH mRNA 水平倾向于高于雄鱼和性反转鱼。此外，MT 分别倾向于降低和增加雌鱼和雄鱼的 GH mRNA 水平。肝和性腺外周水平的 GHR 和 IGF mRNA 在性别间存在显著差异。雌鱼的肝 GHRs 较低，卵巢 GHRs 较高，而雄鱼和性反转鱼则相反。尽管卵巢中的 IGF-1 mRNA 水平较低，但与睾丸相比，IGF-2 mRNA 水平较高。在肝和性腺中，GHRs 和 IGFs 之间存在显著相关性（除 IGF-1 外）。多元回归分析显示，GH mRNA 与肝和性腺中的 GHRs 和 IGFs 之间存在显著关系。MT 对几种生理参数和 GH-IGF 作用表现出雄激素和在一定程度上雌激素的作用。
