Jaffe C A, Ocampo-Lim B, Guo W, Krueger K, Sugahara I, DeMott-Friberg R, Bermann M, Barkan A L
Division of Endocrinology and Metabolism, Department of Internal Medicine, Department of Veterans Affairs Medical Center and University of Michigan Medical Center, Ann Arbor, Michigan 48109-0354, USA.
J Clin Invest. 1998 Jul 1;102(1):153-64. doi: 10.1172/JCI2908.
Sexually dimorphic growth hormone (GH) secretory pattern is important in the determination of gender-specific patterns of growth and metabolism in rats. Whether GH secretion in humans is also sexually dimorphic and the neuroendocrine mechanisms governing this potential difference are not fully established. We have compared pulsatile GH secretion profiles in young men and women in the baseline state and during a continuous intravenous infusion of recombinant human insulin-like growth factor I (rhIGF-I). During the baseline study, men had large nocturnal GH pulses and relatively small pulses during the rest of the day. In contrast, women had more continuous GH secretion and more frequent GH pulses that were of more uniform size. The infusion of rhIGF-I (10 microg/kg/h) potently suppressed both spontaneous and growth hormone-releasing hormone (GHRH)-induced GH secretion in men. In women, however, rhIGF-I had less effect on pulsatile GH secretion and did not suppress the GH response to GHRH. These data demonstrate the existence of sexual dimorphism in the regulatory mechanisms involved in GH secretion in humans. The persistence of GH responses to GHRH in women suggests that negative feedback by IGF-I might be expressed, in part, through suppression of hypothalamic GHRH.
性二态性生长激素（GH）分泌模式在决定大鼠性别特异性生长和代谢模式方面很重要。人类的GH分泌是否也存在性二态性以及控制这种潜在差异的神经内分泌机制尚未完全明确。我们比较了年轻男性和女性在基线状态以及连续静脉输注重组人胰岛素样生长因子I（rhIGF-I）期间的脉冲式GH分泌情况。在基线研究中，男性夜间有较大的GH脉冲，白天其余时间的脉冲相对较小。相比之下，女性的GH分泌更持续，GH脉冲更频繁，且大小更均匀。输注rhIGF-I（10微克/千克/小时）可有效抑制男性自发和生长激素释放激素（GHRH）诱导的GH分泌。然而，在女性中，rhIGF-I对脉冲式GH分泌的影响较小，且不抑制GH对GHRH的反应。这些数据表明人类GH分泌调节机制中存在性二态性。女性对GHRH的GH反应持续存在，这表明IGF-I的负反馈可能部分通过抑制下丘脑GHRH来表达。
