Chapman I M, Helfgott A, Willoughby J O
Department of Medicine, Flinders Medical Centre, South Australia.
J Endocrinol. 1991 Mar;128(3):369-74. doi: 10.1677/joe.0.1280369.
This study was performed to determine the disappearance half-life times of endogenous and exogenous rat GH in conscious normal rats and to compare these with the decay characteristics of GH at the end of spontaneous normal bursts. The endogenous half-life was determined in five rats by giving an i.v. injection of rat GH-releasing factor followed after 10 min by an i.v. injection of long-acting somatostatin analogue (octreotide) and taking blood samples for 85 min. The half-lives (mean +/- S.E.M.) were 3.4 +/- 0.4 min and 13.2 +/- 1.1 min for the first and second exponential respectively as determined by bi-exponential analysis. The exogenous GH half-life was determined in ten rats by giving i.v. octreotide followed after 10 min by i.v. rat GH and sampling for 85 min. The half-lives of exogenous GH were 3.3 +/- 0.2 min and 17.5 +/- 1.4 min by bi-exponential analysis and there was no significant difference between the half-lives of endogenous and exogenous GH. The half-life of the decline of GH levels at the end of spontaneous bursts in nine rats was 14.4 +/- 0.9 min, not different from the half-life of endogenous GH, the secretion of which was terminated by octreotide. This suggests that the end of spontaneous GH bursts is marked by sudden cessation of GH release and may provide an indication of the rapidity of change in the levels of the underlying hypothalamic hormones which control GH release.
本研究旨在测定清醒正常大鼠体内内源性和外源性大鼠生长激素（GH）的消失半衰期，并将其与正常自发脉冲结束时GH的衰减特征进行比较。通过给5只大鼠静脉注射大鼠生长激素释放因子，10分钟后再静脉注射长效生长抑素类似物（奥曲肽），并采集85分钟的血样来测定内源性半衰期。通过双指数分析确定，第一和第二个指数的半衰期（平均值±标准误）分别为3.4±0.4分钟和13.2±1.1分钟。通过给10只大鼠静脉注射奥曲肽，10分钟后再静脉注射大鼠GH并采集85分钟血样来测定外源性GH半衰期。通过双指数分析，外源性GH的半衰期为3.3±0.2分钟和17.5±1.4分钟，内源性和外源性GH的半衰期之间无显著差异。9只大鼠自发脉冲结束时GH水平下降的半衰期为14.4±0.9分钟，与内源性GH的半衰期无差异，内源性GH的分泌被奥曲肽终止。这表明，自发GH脉冲的结束以GH释放的突然停止为标志，可能提示控制GH释放的下丘脑激素水平变化的快速性。
