Coordinated regulation of the GH/IGF system genes during refeeding in rainbow trout (Oncorhynchus mykiss)
Coordinated regulation of the GH/IGF system genes during refeeding in rainbow trout (Oncorhynchus mykiss)
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DOI：
10.1677/joe.1.06869
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发表时间：
2006-10-01
影响因子：
4
通讯作者：
Montserrat, Nuria
中科院分区：
文献类型：
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作者：
Gabillard, Jean-Charles;Kamangar, Barzan Bahrami;Montserrat, Nuria
GH/IGF 系统是一个复杂的调节网络，强烈依赖于营养物质的可用性。虽然饥饿对 GH/IGF 系统的影响已被广泛研究，但饥饿后导致 GH/IGF 系统活性恢复的事件的时间进程在很大程度上尚不清楚。因此，我们测量了 GH、IGF-I 和 IGF-II 的血浆水平以及肝脏和肌肉中 GH/IGF 系统的表达。饥饿会增加血浆 GH 水平，重新喂食 1 天可使其完全恢复（1.10 +/- 0.27 vs 1.12 +/- 0.28 ng/ml）。此后，血浆 GH 持续下降，直到第 7 天，并从第 15 天开始恢复到对照值。饥饿降低了血浆 IGF-I 和 IGF-II，而重新喂养仅从第 4 天开始升高血浆 IGF-I。相反，重新喂养 1 天后血浆 IGF-II 水平翻倍（26.5 +/- 1.9 vs 44.0 +/- 3.4 ng/ml；P < 0.01）。饥饿的鱼在肝脏和肌肉中表现出比对照组更高的 GH 受体 (GHR) 1 mRNA 丰度，而 GHR2 mRNA 丰度仅在肌肉中增加。在肝脏中，重新喂食第一天，GHR1 减少（两倍），但 GHR2 mRNA 丰度增加（两倍）。此后，观察到逐渐恢复至正常值。饥饿的鱼肝脏 IGFBP-4 mRNA 丰度降低，随后在重新喂食期间逐渐恢复。饥饿对肝脏 IGFBP-2 和 IGFBP-6 mRNA 丰度没有影响，而重新喂食会在第 7 天引起 IGFBP-2 和 IGFBP-6 表达峰值。在肌肉中，饥饿导致 IGFBP-2 mRNA 水平下降，仅从第 7 天开始恢复。饥饿鱼中的 IGFBP-4 mRNA 丰度低于对照组和对照组。 再喂食导致 IGFBP-4 基因在第 1 天短暂上调（七倍）。IGF-I、IGFBP-5 和 IGFBP 相关蛋白 1 (rP1) 表达谱相似，显示饥饿后表达减少，第 2 天出现第一个表达峰值，第 7 天出现第二个峰值，并从第 15 天开始恢复到正常值。 IGFBP-5 和 IGFBP-rP1 mRNA 丰度呈正相关（r=0.6-0.8；P < 0.0001）。总之，血浆 IGF-I 的恢复晚于血浆 GH 水平，这表明血浆 IGF-I 水平不能解释血浆 GH 的变化。 IGF-I、IGFBP-5 和 IGFBP-rP1 表达的协调调节将是肌源活性恢复的标志。
The GH/IGF system is a complex regulation network strongly dependent on nutrient availability. While the effect of starvation on the GH/IGF system has been extensively studied, the time course of events leading to the restoration of GH/IGF system activity after starvation is largely unknown. We, therefore, measured the plasma levels of GH, IGF-I and IGF-II and the expression of the GH/IGF system in liver and muscle. Starvation increased the plasma GH level and 1 day of refeeding completely restored it (1.10 +/- 0.27 vs 1.12 +/- 0.28 ng/ml). Thereafter, plasma GH continued to decrease until day 7 and returned to control values from day 15. Starvation decreased plasma IGF-I and IGF-II and refeeding raised plasma IGF-I only from day 4. In contrast, the plasma IGF-II level doubled after 1 day's refeeding (26.5 +/- 1.9 vs 44.0 +/- 3.4 ng/ml; P < 0.01). Starved fish exhibited higher GH receptor (GHR) 1 mRNA abundance in liver and muscle than in controls, whereas GHR2 mRNA abundance was increased only in muscle. In liver, I day of refeeding, decreased GHR1 (twofold), but increased GHR2 mRNA abundance (twofold). Thereafter, a progressive return to normal values was observed. Liver IGFBP-4 mRNA abundance was lowered in starved fish followed by a progressive restoration during refeeding. Starvation had no effect on liver IGFBP-2 and IGFBP-6 mRNA abundance, whereas refeeding provoked a peak of IGFBP-2 and IGFBP-6 expression at day 7. In muscle, starvation led to a decrease of the IGFBP-2 mRNA level, which was restored only from day 7. IGFBP-4 mRNA abundance in starved fish was lower than in the controls and refeeding led to a transient upregulation (sevenfold) of IGFBP-4 gene at day 1. IGF-I, IGFBP-5, and IGFBP-related protein 1 (rP1) expression profiles were similar, showing a decrease of expression after starvation, a first peak of expression at day 2, a second peak at day 7, and a return to normal value from day 15. Moreover, IGF-I, IGFBP-5, and IGFBP-rP1 mRNA abundance were positively correlated (r=0.6-0.8; P < 0.0001). In conclusion, plasma IGF-I was restored later than plasma GH level, which suggests that plasma IGF-I levels cannot account for plasma GH changes. The coordinated regulation of IGF-I, IGFBP-5, and IGFBP-rP1 expression would be a signature for the resumption of myogenic activity.