Veldhuis J D, Liem A Y, South S, Weltman A, Weltman J, Clemmons D A, Abbott R, Mulligan T, Johnson M L, Pincus S
Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
J Clin Endocrinol Metab. 1995 Nov;80(11):3209-22. doi: 10.1210/jcem.80.11.7593428.
A chemiluminescence-based GH assay with 30- to 100-fold increased sensitivity recently disclosed combined basal and pulsatile GH secretion in men. However, how age, sex steroid hormones, and obesity singly and jointly influence the basal vs. pulsatile modes of GH release is not known. We used the foregoing assay (detection threshold, 0.002-0.005 microgram/L) and high sensitivity and specificity (> or = 90% each) deconvolution analysis to quantitate basal and pulsatile GH secretion from 24-h serum GH concentration profiles in 26 healthy lean and obese men, whose ages spanned 18-63 yr and whose percentage body fat ranged from 12-47%. Concentrations of serum insulin-like growth factor I (IGF-I), IGF-I-binding protein-1 (IGFBP-1), and IGFBP-3 were related to specific measures of basal or pulsatile GH release. We observed that mean (24-h) serum GH concentrations embraced a 140-fold range from 0.013-1.8 micrograms/L and were related negatively to age (r = -0.50; P < 0.01), percentage body fat (r = -0.620; P < 0.01), and their interaction (r = -0.610; P < 0.01). In contrast, testosterone was a robustly positive statistical determinant of mean serum GH values (r = 0.628; P = 0.0006). Stepwise multivariate regression analysis disclosed that percentage body fat alone and jointly with the serum testosterone concentration controlled, respectively, 38% and 50% of the total variability in GH levels (P = 0.0013 and P = 0.0008). As assessed by deconvolution analysis, GH secretory burst mass was negatively related to percentage body fat (r = -0.621; P < 0.01) and positively to serum testosterone (r = 0.529; P = 0.0054). The calculated half-life of GH correlated positively with serum estradiol (r = 0.447; P = 0.032), and negatively with percentage body fat (r = -0.437; P = 0.048). Basal GH secretion rates were negatively related to serum estradiol (r = -0.485; P = 0.016). In contrast, GH secretory burst frequency and duration were unrelated to age, percentage body fat, or sex steroids. The fraction of total GH secreted in bursts was negatively correlated with the body mass index (r = -0.540; P < 0.01). Serum IGF-I concentrations were positively related to total pulsatile GH secretion (r = 0.690; P = 0.0011) and negatively to age (r = -0.597; P = 0.007) and percentage body fat (r = -0.611; P = 0.009).(ABSTRACT TRUNCATED AT 400 WORDS)
一种基于化学发光的生长激素（GH）检测方法，其灵敏度提高了30至100倍，最近揭示了男性基础和脉冲式GH分泌的情况。然而，年龄、性类固醇激素和肥胖如何单独及共同影响GH释放的基础模式与脉冲模式尚不清楚。我们使用上述检测方法（检测阈值为0.002 - 0.005微克/升）以及高灵敏度和特异性（均≥90%）的去卷积分析，对26名年龄在18至63岁、体脂百分比在12%至47%之间的健康瘦型和肥胖男性24小时血清GH浓度曲线中的基础和脉冲式GH分泌进行定量。血清胰岛素样生长因子I（IGF - I）、IGF - I结合蛋白 - 1（IGFBP - 1）和IGFBP - 3的浓度与基础或脉冲式GH释放的特定指标相关。我们观察到，平均（24小时）血清GH浓度范围为0.013至1.8微克/升，相差140倍，且与年龄呈负相关（r = -0.50；P < 0.01）、与体脂百分比呈负相关（r = -0.620；P < 0.01）以及与它们的相互作用呈负相关（r = -0.610；P < 0.01）。相比之下，睾酮是平均血清GH值的一个强有力的正性统计学决定因素（r = 0.628；P = 0.0006）。逐步多元回归分析表明，单独的体脂百分比以及与血清睾酮浓度共同作用，分别控制了GH水平总变异性的38%和50%（P = 0.0013和P = 0.0008）。通过去卷积分析评估，GH分泌脉冲量与体脂百分比呈负相关（r = -0.621；P < 0.01），与血清睾酮呈正相关（r = 0.529；P = 0.0054）。计算得出的GH半衰期与血清雌二醇呈正相关（r = 0.447；P = 0.032），与体脂百分比呈负相关（r = -0.437；P = 0.048）。基础GH分泌率与血清雌二醇呈负相关（r = -0.485；P = 0.016）。相比之下，GH分泌脉冲频率和持续时间与年龄、体脂百分比或性类固醇无关。脉冲式分泌的GH占总GH的比例与体重指数呈负相关（r = -0.540；P < 0.01）。血清IGF - I浓度与总脉冲式GH分泌呈正相关（r = 0.690；P = 0.0011），与年龄呈负相关（r = -0.597；P = 0.007），与体脂百分比呈负相关（r = -0.611；P = 0.009）。（摘要截选至400字）
