Nørrelund Helene, Frystyk Jan, Jørgensen Jens Otto Lunde, Møller Niels, Christiansen Jens Sandahl, Ørskov Hans, Flyvbjerg Allan
Medical Department M (Endocrinology and Diabetes), Aarhus Kommunehospital, Aarhus, Denmark.
J Clin Endocrinol Metab. 2003 Jul;88(7):3292-8. doi: 10.1210/jc.2002-021983.
The present study investigates the possible stimulatory effect of endogenous GH on IGF and IGF-binding protein (IGFBP) levels during fasting. Eight normal subjects were examined on four occasions: 1) in the basal postabsorptive state; 2) after 40 h of fasting; 3) after 40 h of fasting with somatostatin suppression of GH; and 4) after 40 h of fasting with suppression of GH and exogenous GH replacement. The two somatostatin experiments were identical in terms of hormone replacement (except for GH). Short-term fasting led to a 50% reduction in free IGF-I. The reduction in free IGF-I was paralleled by an increase in IGFBP-1, an increase in the complex formation of IGFBP-1 and IGF-I, and a modest reduction in IGFBP-3 proteolysis. GH deprivation during fasting led to a 35% reduction in total IGF-I and a 70% reduction in free IGF-I. GH replacement increased free and total IGF-I to levels similar to those observed during plain fasting and decreased IGFBP-1, however, without affecting IGFBP-1-bound IGF-I. Finally, IGFBP-3 proteolysis was slightly increased by GH replacement. In conclusion, the major new finding of the present study is that the GH hypersecretion seen during short-term fasting is not merely secondary to a reduction in IGF bioactivity.
本研究调查了内源性生长激素（GH）在禁食期间对胰岛素样生长因子（IGF）和IGF结合蛋白（IGFBP）水平可能产生的刺激作用。对8名正常受试者进行了4次检查：1）基础吸收后状态；2）禁食40小时后；3）禁食40小时且生长抑素抑制生长激素后；4）禁食40小时且生长激素被抑制并进行外源性生长激素替代后。两项生长抑素实验在激素替代方面（除生长激素外）是相同的。短期禁食导致游离IGF-I降低50%。游离IGF-I的降低伴随着IGFBP-1的增加、IGFBP-1与IGF-I复合物形成的增加以及IGFBP-3蛋白水解的适度降低。禁食期间生长激素缺乏导致总IGF-I降低35%，游离IGF-I降低70%。生长激素替代使游离和总IGF-I增加至与单纯禁食时观察到的水平相似，并降低了IGFBP-1，然而，并未影响与IGFBP-1结合的IGF-I。最后，生长激素替代使IGFBP-3蛋白水解略有增加。总之，本研究的主要新发现是，短期禁食期间出现的生长激素分泌过多不仅仅是IGF生物活性降低的继发结果。
