Nass Ralf, Farhy Leon S, Liu Jianhua, Prudom Catherine E, Johnson Michael L, Veldhuis Paula, Pezzoli Suzan S, Oliveri Mary Clancy, Gaylinn Bruce D, Geysen H Mario, Thorner Michael O
Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA.
J Clin Endocrinol Metab. 2008 May;93(5):1988-94. doi: 10.1210/jc.2007-2234. Epub 2008 Mar 11.
The timing and frequency of GH secretory episodes is regulated by GHRH and somatostatin. This study provides evidence for amplification of these GH pulses by endogenous acyl-ghrelin.
Blood was sampled every 10 min for 26.5 h during a fed admission with standardized meals and also during the final 24 h of a 61.5-h fast. GH secretion profiles were derived from deconvolution of 10-min sampling data, and full-length acyl-ghrelin levels were measured using a newly developed two-site sandwich assay.
The study was conducted at a university hospital general clinical research center.
Participants included eight men with mean (+/- sd) age 24.5 +/- 3.7 yr (body mass index 24 +/- 2.1 kg/m(2)).
Correlations were computed between amplitudes of individual GH secretory events and the average acyl-ghrelin concentration in the 60-min interval preceding each GH burst. In the fed state, the peak correlations were positive for all subjects and significantly higher than in the fasting state when acyl-ghrelin levels declined [mean (+/- sem): 0.7 (0.04) vs. 0.29 (0.08), P = 0.017]. In addition, long-term fasting was associated with an increase in the GH secretory pulse mass and amplitude but not frequency [fed vs. fasting pulse mass: 0.22 (0.05) vs. 0.44 (0.06) microg/liter, P = 0.002; amplitude: 5.2 (1.3) vs. 11.8 (1.9) microg/liter/min, P = 0.034; pulses per 24 h: 19.4 (0.5) vs. 22.0 (1.4), P = 0.1].
Our data support the hypothesis that under normal conditions in subjects given regular meals endogenous acyl-ghrelin acts to increase the amplitude of GH pulses.
生长激素（GH）分泌脉冲的时间和频率受生长激素释放激素（GHRH）和生长抑素调节。本研究为内源性酰基胃饥饿素放大这些GH脉冲提供了证据。
在进食标准化餐食的进食期26.5小时内，以及61.5小时禁食的最后24小时内，每隔10分钟采集一次血液样本。GH分泌曲线由10分钟采样数据的反卷积得出，全长酰基胃饥饿素水平使用新开发的双位点夹心分析法进行测定。
该研究在大学医院综合临床研究中心进行。
参与者包括8名男性，平均（±标准差）年龄24.5±3.7岁（体重指数24±2.1kg/m²）。
计算了各个GH分泌事件的幅度与每个GH脉冲前60分钟间隔内酰基胃饥饿素平均浓度之间的相关性。在进食状态下，所有受试者的峰值相关性均为正，且显著高于禁食状态下酰基胃饥饿素水平下降时的相关性[平均（±标准误）：0.7（0.04）对0.29（0.08），P = 0.017]。此外，长期禁食与GH分泌脉冲量和幅度增加有关，但与频率无关[进食与禁食脉冲量：0.22（0.05）对0.44（0.06）μg/升，P = 0.002；幅度：5.2（1.3）对11.8（1.9）μg/升/分钟，P = 0.034；每24小时脉冲数：19.4（
