Nogami H, Watanabe T, Kobayashi S
Department of Anatomy, Jikei University School of Medicine, Tokyo, Japan.
Am J Physiol. 1994 Sep;267(3 Pt 1):E396-401. doi: 10.1152/ajpendo.1994.267.3.E396.
Effects of growth hormone (GH) and fasting on hepatic expressions of insulin-like growth factor I (IGF-I) and IGF-I-binding protein (IGFBP)-1, -2, -3, and -4 were examined in spontaneous dwarf rats (SDR), which completely and specifically lack GH among pituitary hormones. The hepatic expressions of mRNA encoding IGF-I and IGFBP-3 were reduced and IGFBP-1 mRNA was elevated in the SDR. Both chronic and acute administration of GH restored these changes, indicating the association of GH but not other pituitary hormones with hepatic expressions of these genes. In addition, the present examination revealed that mRNA level of IGFBP-2 was elevated in SDR, which could not be attenuated by exogenous GH, and that GH may not be directly relevant to the regulation of hepatic IGFBP-4 expression. Fasting for 2 days reduced IGF-I mRNA level and increased IGFBP-2 mRNA level in the SDR, as well as in the normal rat, suggesting the presence of factors other than reduced serum GH responsible for fasting-induced alteration in the expression of these mRNAs. On the other hand, fasting resulted in little change or even a reduction of IGFBP-1 mRNA level in the SDR.
在自发矮小大鼠（SDR）中检测了生长激素（GH）和禁食对肝脏胰岛素样生长因子I（IGF-I）及IGF-I结合蛋白（IGFBP）-1、-2、-3和-4表达的影响，SDR在垂体激素中完全且特异性缺乏GH。SDR中编码IGF-I和IGFBP-3的mRNA肝脏表达降低，而IGFBP-1 mRNA升高。GH的慢性和急性给药均恢复了这些变化，表明GH而非其他垂体激素与这些基因的肝脏表达有关。此外，本研究还显示，SDR中IGFBP-2的mRNA水平升高，外源性GH无法使其减弱，且GH可能与肝脏IGFBP-4表达的调节无直接关系。禁食2天降低了SDR以及正常大鼠中IGF-I mRNA水平并增加了IGFBP-2 mRNA水平，提示除血清GH降低外，还存在其他因素导致禁食诱导这些mRNA表达改变。另一方面，禁食导致SDR中IGFBP-1 mRNA水平几乎无变化甚至降低。
