National Institute of Nutrition and Seafood Research (NIFES), Nordnes, Bergen, Norway.
Fish Physiol Biochem. 2011 Mar;37(1):217-32. doi: 10.1007/s10695-010-9434-3. Epub 2010 Sep 29.
The effects of short-time fasting on appetite, growth, and nutrient were studied in Atlantic salmon (Salmo salar) smolts. Feed deprivation did change the energy metabolism with reduced plasma protein and muscle indispensible amino acid levels. Plasma levels of ghrelin were significantly higher in starved salmon compared with fed fish after 2 days, but no differences in circulating ghrelin were found between treatments after 14 days. Two mRNA sequences for ghrelin-1 and ghrelin-2, 430 and 533 bp long, respectively, were detected. In addition, the growth hormone secretagogues-receptor like receptor (GHSR-LR) 1a and 1b were identified. Ghrelin-1 but not ghrelin-2 mRNA levels were affected by starvation in the stomach. Lower ghrelin-1 mRNA levels were detected at day 2 in starved fish compared with fed fish. The mRNA levels of GHSR-LR1a were not affected by starvation. Fasting reduced the phenotypic growth and the transcription of insulin-like growth factor (IGF)-II together with IGF-IIR, but IGF-I mRNA were not regulated in fasted salmon after 14 days. Three IGF-binding proteins (IGFBP) at 23, 32, and 43 kDa were found in salmon, and circulating 23 kDa was significantly increased after 14 days of starvation compared with fed fish, indicating increased catabolism. The levels of IGFBP-1 mRNA were significantly higher in fed and starved fish after 14 days compared to those at the start of the experiment, but no significant difference was observed between the treatments. In conclusion, we have shown that circulating ghrelin and ghrelin-1 mRNA is related to changes in energy metabolism in Atlantic salmon.
研究了大西洋鲑（Salmo salar）幼鱼短期禁食对食欲、生长和营养的影响。禁食确实改变了能量代谢，导致血浆蛋白和肌肉必需氨基酸水平降低。与摄食组相比，禁食 2 天后，饥饿鲑鱼的血浆胃饥饿素水平显著升高，但 14 天后两组间循环胃饥饿素无差异。检测到两种胃饥饿素-1 和胃饥饿素-2 的 mRNA 序列，分别长 430 和 533bp。此外，还鉴定了生长激素促分泌素受体样受体（GHSR-LR）1a 和 1b。胃饥饿素-1 而不是胃饥饿素-2 的 mRNA 水平受饥饿影响。与摄食组相比，饥饿组鱼在第 2 天的胃饥饿素-1 mRNA 水平较低。GHSR-LR1a 的 mRNA 水平不受饥饿影响。禁食降低了表型生长和胰岛素样生长因子（IGF）-II 及其受体 IGF-IIR 的转录，但在 14 天后，禁食鲑鱼的 IGF-I mRNA 不受调节。在鲑鱼中发现了三种 IGF 结合蛋白（IGFBP），分子量为 23、32 和 43 kDa，禁食 14 天后循环 23 kDa IGFBP 显著增加，表明分解代谢增加。与实验开始时相比，禁食和摄食组鱼在 14 天后的 IGFBP-1 mRNA 水平显著升高，但两组间无显著差异。总之，我们表明循环胃饥饿素和胃饥饿素-1 mRNA 与大西洋鲑能量代谢变化有关。
