Physiological role of IGF-I in the nutrition of central nervous system

为了阐明IGF-I在中枢神经系统营养中的生理作用，我们进行了以下研究：(1)将IGF-I、IGF-II和IGF结合蛋白基因表达的营养与中枢神经系统的营养结合方式联系起来：(2)阐明神经系统在组织营养中的作用。IGF-I在脑各部位均有表达，但在大脑中表达较少，在小脑和中脑中表达较少。另一方面，IGF-II基因在脑内各部位均有表达。在IGFBP-1、BP-2和BP-3中，只有IGFBP-2在脑内广泛表达。Dicary蛋白不影响脑内IGF-I、IGF-II和IGFBP-2的mRNA含量，可能反映了脑营养的保守性。提示脑营养的调节不是通过IGF-I的内分泌模式，而是自分泌/旁分泌模式。至于神经系统在组织营养中的作用，对失神经肌肉的蛋白质代谢进行了详细的研究。

To elucidate the physiological role of IGF-I in the nutrition of central nervous system, the following studies were performed.(1) Relate the effect of nutrition of the expressioin of IGF-I,IGF-II and IGF-binding protein genes to the mode of nutrient incorporation by the central nervous.(2) Elucidate the role of nervous system in the nutrition of tissues.Gene expression of IGF-I,IGF-II and IGF-binding prteins was studied in various portions of rat brain. IGF-I mRNA was found in various portions of brain but it was scarcely found in cerebrum and not so much in cerebellum and midbrain. On the other hand, IGF-II mRNA was found in every portion of brain. Among IGFBP-1 BP-2 and BP-3, only IGFBP-2 mRNA was found in brain extensively. Dictary protein did not affect the mRNA contents of IGF-I,IGF-II and IGFBP-2 in brain, probably reflecting the conservative nature of brain nutrition. It was suggested that brain nutrition is regulated not by endocrine mode of IGF-I action but by autocrine/paracrine mode of IGF-I action.As for the role of nervous system in the nutrition of tissues, protein metabolism of denervated muscle was studied in detail.