Paulo Remberto C, Cosma Mihaela, Soares-Welch Cacia, Bailey Joy N, Mielke Kristi L, Miles John M, Bowers Cyril Y, Veldhuis Johannes D
Department of Pediatrics, Endocrine Research Unit, Clinical Translational Research Center, Mayo Medical and Graduate Schools, Mayo Clinic, Rochester, Minnesota 55901, USA.
J Clin Endocrinol Metab. 2008 Mar;93(3):944-50. doi: 10.1210/jc.2007-1388. Epub 2007 Dec 11.
Sex steroid hormones potentiate whereas increased body mass index (BMI) represses GH secretion. Whether sex steroids modify the negative effect of BMI on secretagogue-induced GH secretion in men is not known. The issue is important in designing GH-stimulation regimens that are relatively insensitive to both gonadal status and adiposity.
Our objective was to compare the relationships between BMI and peptide-stimulated GH secretion in men with normal and reduced testosterone and estradiol availability.
The study was performed at an academic medical center.
Healthy young men were included in the study.
Randomized separate-day iv infusion of saline and/or maximally effective doses of L-arginine/GHRH, L-arginine/GH-releasing peptide (GHRP)-2, and GHRH/GHRP-2 in eugonadal (n=12) and experimentally hypogonadal (n=10) men was performed.
Regression of paired secretagogue-induced GH responses on BMI was determined.
In eugonadal men, peak GH concentrations correlated negatively with BMI. In particular, BMI accounted for only 38% of the response variability after L-arginine/GHRH (P=0.0165), but 62% after GHRH/GHRP-2 (P=0.0012) and 65% after L-arginine/GHRP-2 (P=0.00075). In contrast, in hypogonadal men, GH responses were uncorrelated with BMI. The negative effects of BMI on peak GH responses in eugonadal and hypogonadal states differed most markedly after stimulation with GHRH/GHRP-2 (P=0.0019). This contrast was corroborated using integrated GH responses (P=0.0007).
Short-term experimental gonadal sex hormone depletion attenuates dual secretagogue-stimulated GH secretion in lean young men. The inhibitory effect of relative adiposity on GH secretion appears to predominate over that of acute sex steroid withdrawal.
性类固醇激素可增强生长激素（GH）分泌，而体重指数（BMI）升高则会抑制GH分泌。目前尚不清楚性类固醇是否会改变BMI对男性促分泌素诱导的GH分泌的负面影响。这一问题对于设计对性腺状态和肥胖均相对不敏感的GH刺激方案具有重要意义。
我们的目的是比较睾酮和雌二醇水平正常及降低的男性中BMI与肽刺激的GH分泌之间的关系。
该研究在一家学术医疗中心进行。
健康年轻男性纳入本研究。
对性腺功能正常（n = 12）和实验性性腺功能减退（n = 10）的男性，在不同日期随机静脉输注生理盐水和/或最大有效剂量的L-精氨酸/生长激素释放激素（GHRH）、L-精氨酸/生长激素释放肽（GHRP）-2以及GHRH/GHRP-2。
确定成对的促分泌素诱导的GH反应与BMI之间的回归关系。
在性腺功能正常的男性中，GH峰值浓度与BMI呈负相关。具体而言，L-精氨酸/GHRH刺激后，BMI仅占反应变异性的38%（P = 0.0165），但GHRH/GHRP-2刺激后为62%（P = 0.0012），L-精氨酸/GHRP-2刺激后为65%（P = 0.00075）。相比之下，在性腺功能减退的男性中，GH反应与BMI无关。在GHRH/GHRP-2刺激后，BMI对性腺功能正常和减退状态下GH峰值反应的负面影响差异最为明显（P = 0.0019）。使用整合的GH反应也证实了这种差异（P = 0.0007）。
短期实验性性腺性激素缺乏会减弱瘦年轻男性中双重促分泌素刺激的GH分泌。相对肥胖对GH分泌的抑制作用似乎超过急性性激素撤除的作用。
