Winer L M, Shaw M A, Baumann G
Center for Endocrinology, Metabolism, and Nutrition, Department of Medicine, Northwestern University Medical School 60611.
J Clin Endocrinol Metab. 1990 Jun;70(6):1678-86. doi: 10.1210/jcem-70-6-1678.
Circulating GH levels in man fluctuate widely due to pulsatile GH secretion by the pituitary gland. During much of the time, plasma GH is undetectable by current assays. This is punctuated by occasional secretory episodes, resulting in plasma GH peaks of varying height. The principal diurnal secretory event for GH is that associated with early slow wave sleep, but little is known about the prevailing level and dynamics of GH during the day. We used a new ultrasensitive immunoradiometric assay for GH (Boots-Celltech IRMA; limit of detection, 20 ng/L) to measure plasma GH in the previously undetectable range and to assess its diurnal pattern. Plasma GH was measured every 20 min over a 24-h period in 12 normal subjects (6 men and 6 women, aged 20-47 yr) under physiological conditions. Time series analysis of plasma GH patterns was performed by the Cluster algorithm, autocorrelation, and spectral analysis. Plasma GH, as measured by IRMA, was detectable at all time points and ranged from 40-19,695 ng/L. Dynamic fluctuations occurred within and above the previously undetectable range, with amplitudes varying over 3 orders of magnitude. Women had significantly higher overall GH levels, higher peak amplitudes, and higher valley levels/nadirs than men. GH pulses occurred with an average frequency of about 13/day in both sexes, with a dominant, but not strictly periodic, 2-h rhythmicity. We conclude that in man pulsatile GH secretion occurs throughout the day, and that it is oscillatory rather than episodic. This neurosecretory pattern has eluded recognition heretofore because of the lack of assay sensitivity. Women of reproductive age have higher pulse amplitudes and a higher baseline but equal pulse frequency compared to men. Previous estimates of integrated GH concentrations and GH production rates were too high by a factor of 2 due to overestimation of GH levels in the undetectable range.
由于垂体的脉冲式生长激素（GH）分泌，人体循环中的GH水平波动很大。在大部分时间里，目前的检测方法无法检测到血浆中的GH。偶尔的分泌高峰会打断这种情况，导致血浆GH出现不同高度的峰值。GH的主要昼夜分泌事件与早期慢波睡眠有关，但对于白天GH的主要水平和动态变化知之甚少。我们使用了一种新的超灵敏GH免疫放射分析方法（Boots-Celltech IRMA；检测限为20 ng/L）来测量血浆中之前无法检测到范围内的GH，并评估其昼夜模式。在生理条件下，对12名正常受试者（6名男性和6名女性，年龄20 - 47岁）在24小时内每隔20分钟测量一次血浆GH。通过聚类算法、自相关和频谱分析对血浆GH模式进行时间序列分析。通过IRMA测量的血浆GH在所有时间点都可检测到，范围为40 - 19,695 ng/L。在之前无法检测到的范围内及以上都出现了动态波动，幅度变化超过3个数量级。女性的总体GH水平、峰值幅度和谷值水平/最低点均显著高于男性。两性中GH脉冲的平均频率约为每天13次，具有占主导地位但并非严格周期性的2小时节律。我们得出结论，在人类中，脉冲式GH分泌全天都在发生，并且是振荡性的而非间歇性的。由于缺乏检测灵敏度，这种神经分泌模式此前一直未被认识到。与男性相比，育龄女性的脉冲幅度更高，基线更高，但脉冲频率相同。由于对无法检测到范围内的GH水平估计过高，之前对GH综合浓度和GH产生率的估计高出了2倍。
