Baños N, Baró J, Castejón C, Navarro I, Gutiérrez J
Departament Fisiologia, Fac. Biologia, Universitat de Barcelona, Spain.
Regul Pept. 1998 Oct 16;77(1-3):55-62. doi: 10.1016/s0167-0115(98)00041-x.
Insulin and insulin growth factor-I (IGF-I) binding to skeletal muscle semipurified receptors were assessed in rainbow trout (Oncorhynchus mykiss) fed with different enriched carbohydrate diets. The animals were fed for 2 months, either in spring, summer or autumn with a control diet (C, commercial diet containing 21% raw carbohydrates) or with two diets supplied with highly digestible carbohydrates (E1, 22% expanded wheat; and E2, 37% expanded wheat). Insulin and IGF-I receptors were semipurified by affinity chromatography (WGA-agarose). Fish fed with a carbohydrate enriched diet did not show lower growth rates than those fed with the control diet. Independently of the season, rainbow trout fed E1 and E2 presented higher insulin and glucose plasma levels as well as higher tissue glycogen reserves than fish fed C. An increase in the number of insulin receptors during the diet adaptation was observed especially in fish fed with E2. No differences in the affinity of receptors were observed. IGF-I specific binding in skeletal muscle was higher than that of insulin in all groups and in all seasons. Furthermore, IGF-I receptors showed the same tendency as insulin receptors, with increases in their number in experimentally fed fish, especially those fed with E2. Insulin and IGF-I receptors TKA increased only slightly, as a consequence of E1 and E2 diet adaptation. In conclusion, rainbow trout can be fed high-carbohydrate levels and show good rates of growth. This adaptation determines increases in circulating glucose and insulin, and muscle insulin receptors, which indicate an adaptation of the fish to higher levels of glucose supply. The response of IGF-I receptors also suggests a possible role in the regulation of metabolism.
在投喂不同高碳水化合物饲料的虹鳟（Oncorhynchus mykiss）中，评估了胰岛素和胰岛素样生长因子-I（IGF-I）与骨骼肌半纯化受体的结合情况。在春季、夏季或秋季，将实验动物投喂对照饲料（C，含21%天然碳水化合物的商业饲料）或两种富含高消化率碳水化合物的饲料（E1，22%膨化小麦；E2，37%膨化小麦），为期2个月。通过亲和层析（WGA-琼脂糖）对胰岛素和IGF-I受体进行半纯化。投喂高碳水化合物饲料的鱼的生长率并不低于投喂对照饲料的鱼。无论季节如何，投喂E1和E2的虹鳟的血浆胰岛素和葡萄糖水平以及组织糖原储备均高于投喂C的鱼。在饲料适应过程中，尤其是投喂E2的鱼，观察到胰岛素受体数量增加。未观察到受体亲和力的差异。在所有组和所有季节中，骨骼肌中IGF-I的特异性结合均高于胰岛素。此外，IGF-I受体与胰岛素受体表现出相同的趋势，即在实验投喂的鱼中，尤其是投喂E2的鱼，其数量增加。由于E1和E2饲料适应，胰岛素和IGF-I受体的总激酶活性仅略有增加。总之，虹鳟可以投喂高碳水化合物水平的饲料并表现出良好的生长率。这种适应性决定了循环葡萄糖和胰岛素以及肌肉胰岛素受体的增加，这表明鱼对更高水平的葡萄糖供应具有适应性。IGF-I受体的反应也表明其在代谢调节中可能发挥作用。
