Differential effects of chronic hypoxia and feed restriction on the expression of leptin and its receptor, food intake regulation and the endocrine stress response in common carp
Differential effects of chronic hypoxia and feed restriction on the expression of leptin and its receptor, food intake regulation and the endocrine stress response in common carp
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DOI：
10.1242/jeb.066183
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发表时间：
2012-07-01
影响因子：
2.8
通讯作者：
Flik, Gert
中科院分区：
文献类型：
--
作者：
Bernier, Nicholas J.;Gorissen, Marnix;Flik, Gert
食欲抑制是鱼类对缺氧的一种常见反应，可以节省大量能量。然而，我们对慢性缺氧时参与调节食物摄入的内分泌信号知之甚少。因此，我们评估了慢性缺氧对鲤鱼摄食量、强效厌食信号瘦素及其受体（lepr）的表达、下丘脑食欲调节关键基因mRNA水平和下丘脑-垂体-肾间轴（HPI）活性的影响。暴露在10% O-2饱和度下8天的鱼慢性厌食症，平均比正常对照组少消耗79%的食物。缺氧还引起肝脏瘦素a- i、瘦素a- ii、麻风素和促红细胞生成素（一种已知的缺氧反应基因）表达的逐渐和平行增加。相比之下，这四个基因的肝脏mRNA水平在双喂的低氧鱼中保持不变。在下丘脑中，食欲调节基因的表达分别与缺氧和配对喂养的鱼的饥饿抑制和刺激一致，并且采食量的减少导致麻风病的减少。尽管两种治疗方法都引起了类似的血浆皮质醇的延迟增加，但它们的特点是HPI轴效应转录物水平不同，垂体麻风素表达明显不同。综上所述，这些结果表明，O-2可用性的减少，而不是采食量的减少，刺激了普通鲤鱼肝脏瘦素-a的表达，并表明这种多效细胞因子参与了慢性缺氧期间食欲和内分泌应激反应的调节。
Appetite suppression is a common response to hypoxia in fish that confers significant energy savings. Yet little is known about the endocrine signals involved in the regulation of food intake during chronic hypoxia. Thus, we assessed the impact of chronic hypoxia on food intake, the expression of the potent anorexigenic signal leptin and its receptor (lepr), the mRNA levels of key hypothalamic appetite-regulating genes, and the activity of the hypothalamic-pituitary-interrenal (HPI) axis in common carp, Cyprinus carpio. Fish exposed to 10% O-2 saturation for 8 days were chronically anorexic and consumed on average 79% less food than normoxic controls. Hypoxia also elicited gradual and parallel increases in the expression of liver leptin-a-I, leptin-a-II, lepr and erythropoietin, a known hypoxia-responsive gene. In contrast, the liver mRNA levels of all four genes remained unchanged in normoxic fish pair-fed to the hypoxia treatment. In the hypothalamus, expression of the appetite-regulating genes were consistent with an inhibition and stimulation of hunger in the hypoxic and pair-fed fish, respectively, and reduced feed intake led to a decrease in lepr. Although both treatments elicited similar delayed increases in plasma cortisol, they were characterized by distinct HPI axis effector transcript levels and a marked differential increase in pituitary lepr expression. Together, these results show that a reduction in O-2 availability, and not feed intake, stimulates liver leptin-a expression in common carp and suggest that this pleiotropic cytokine is involved in the regulation of appetite and the endocrine stress response during chronic hypoxia.