Marine Biochemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
PLoS One. 2013 Aug 19;8(8):e71421. doi: 10.1371/journal.pone.0071421. eCollection 2013.
Growth and development in fish are regulated to a major extent by growth-related factors, such as liver-derived insulin-like growth factor (IGF) -1 in response to pituitary-secreted growth hormone (GH) binding to the GH receptor (GHR). Here, we report on the changes in the expressions of gh, ghr, and igf1 genes and the circulating levels of GH and IGF-1 proteins in juvenile coho salmon (Oncorhynchus kisutch) in response to handling as an acute physiological stressor. Plasma GH levels were not significantly different between stressed fish and prestressed control. Plasma IGF-1 concentrations in stressed fish 1.5 h post-stress were the same as in control fish, but levels in stressed fish decreased significantly 16 h post-stress. Real-time quantitative PCR (qPCR) analysis showed that ghr mRNA levels in pituitary, liver, and muscle decreased gradually in response to the stressor. After exposure to stress, hepatic igf1 expression transiently increased, whereas levels decreased 16 h post-stress. On the other hand, the pituitary gh mRNA level did not change in response to the stressor. These observations indicate that expression of gh, ghr, and igf1 responded differently to stress. Our results show that acute physiological stress can mainly down-regulate the expressions of growth-related genes in coho salmon in vivo. This study also suggests that a relationship between the neuroendocrine stress response and growth-related factors exists in fish.
鱼类的生长和发育在很大程度上受到生长相关因子的调控，例如肝脏分泌的胰岛素样生长因子（IGF）-1，以响应脑垂体分泌的生长激素（GH）与生长激素受体（GHR）的结合。在这里，我们报告了幼鲑（Oncorhynchus kisutch）在应对急性生理应激源如处理时，gh、ghr 和 igf1 基因的表达变化以及 GH 和 IGF-1 蛋白在循环中的水平。应激鱼和预应激对照组的血浆 GH 水平没有显著差异。应激后 1.5 h 应激鱼的血浆 IGF-1 浓度与对照组鱼相同，但应激后 16 h 应激鱼的水平显著下降。实时定量 PCR（qPCR）分析表明，垂体、肝脏和肌肉中的 ghr mRNA 水平逐渐对胁迫作出反应而降低。暴露于应激后，肝脏 igf1 表达短暂增加，而 16 h 后则降低。另一方面，垂体 gh mRNA 水平对胁迫没有变化。这些观察结果表明，gh、ghr 和 igf1 的表达对应激的反应不同。我们的结果表明，急性生理应激可以主要下调体内鲑鱼生长相关基因的表达。这项研究还表明，鱼类的神经内分泌应激反应与生长相关因子之间存在关系。
