Mechanisms of reduced and compensatory growth
Mechanisms of reduced and compensatory growth
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DOI：
10.1016/s0739-7240(00)00072-2
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发表时间：
2000-08-01
影响因子：
2.1
通讯作者：
Istasse, L
中科院分区：
文献类型：
--
作者：
Hornick, JL;Van Eenaeme, C;Istasse, L
生长是一个综合的过程，是细胞对内分泌状态和营养供应的反应。在限饲期间，脑垂体生长激素（GH）的产生和分泌增加，但GH受体的数量减少。GH结合蛋白的变化诱导GH抵抗，随后是胰岛素样生长因子-I（IGF-I）分泌减少。另一方面，高循环水平的GH增强了脂肪酸的动员，用于支持能量需求。因此，当生长期动物的饲料限制适度时，主要是蛋白质而几乎没有脂肪增加。相比之下，严格的限饲会促进分解代谢激素的释放，并刺激肌肉细胞释放氨基酸，这些氨基酸被肝细胞用于肝细胞的再生。在再喂养和补偿生长期间，胰岛素分泌急剧增强，血浆GH浓度保持高水平。这种情况可能允许更多的营养物质用于生长过程。血浆IGF-I在代偿性生长中的作用尚不清楚，必须结合其结合蛋白的变化来解释。甲状腺素和3，5，3 '-三碘甲状腺原氨酸似乎对生长有许可作用。青春期与再喂养的同时发生可以对生长产生协同效应。最初，补偿性生长的特征是瘦肉组织的沉积，与限饲期间类似。这会持续几个星期。然后，蛋白质合成减少，高采食量导致脂肪沉积增加。(C)2000 Elsevier Science Inc. All rights reserved.
Growth is an integrated process, resulting from the response of cells dependent on the endocrine status and nutrient availability. During feed restriction, the production and secretion of growth hormone (GH) by the pituitary gland are enhanced, but the number of GH receptors decreases. Changes of GH binding proteins induce GH resistance and are followed by reduced insulin-like growth factor-I (IGF-I) secretion. On the other hand, high circulating levels of GH enhance the mobilization of fatty acids, which are used to support energy requirements. Thus, when feed restriction in growing animals is moderate, there is mainly protein but barely fat accretion. By contrast, a severe feed restriction enhances the release of catabolic hormones and stimulates, from muscle cells, the liberation of amino acids, which are used by hepatocytes for gluconeogenesis. During refeeding and compensatory growth, the secretion of insulin is sharply enhanced and plasma GH concentrations remain high. This situation probably allows more nutrients to be used for growth processes. The role of plasma IGF-I during compensatory growth is not clear and must be explained in connection with changes of its binding proteins. Thyroxin and 3,5,3'-triiodothyronine seem to have a permissive effect on growth. The simultaneous occurrence of puberty with refeeding can exert a synergistic effect on growth. Initially, compensatory growth is characterized by the deposition of very lean tissue, similar as during feed restriction. This lasts for some weeks. Then, protein synthesis decreases and high feed intake leads to increased fat deposition. (C) 2000 Elsevier Science Inc. All rights reserved.