Meeking D R, Wallace J D, Cuneo R C, Forsling M, Russell-Jones D L
Department of Endocrinology, St Thomas' Hospital, United Medical and Dental Schools of Guy's and St Thomas' Hospitals, London, UK.
Eur J Endocrinol. 1999 Jul;141(1):22-6. doi: 10.1530/eje.0.1410022.
There is evidence that melatonin may play a role in modulating pituitary secretion, although the mechanisms are unclear. We examined the effects of a single dose of oral melatonin (5mg) on exercise-induced GH secretion. In a randomised, double-blind, placebo-controlled study, seven healthy male subjects undertook an initial period of graded bicycle ergometric exercise to determine maximum workload and oxygen uptake (VO(2max)). Subjects were subsequently studied on two further occasions, receiving either melatonin or placebo in random order at the onset of each study (-60min). At 0 min a period of bicycle exercise was performed for 8 min at a workload corresponding to 70% of that achieved at VO(2max). Serum GH and IGF-binding protein-1 (IGFBP-1) concentration was measured at 15-min intervals from the onset of the study until 120 min post-exercise. Blood was also sampled for the measurement of plasma glucose, insulin, non-esterified fatty acids, IGFBP-3, melatonin and vasopressin concentration. There was an exercise-induced increase in GH concentration following melatonin which was greater compared with placebo as assessed by both area under the curve (P<0.01) and peak increase in GH levels (P<0.01). The peak increase in IGFBP-1 levels post-exercise was also significantly greater following melatonin compared with placebo (P<0. 01) but did not quite reach levels of significance as measured by area under the curve (P=0.07). Since exercise-induced GH secretion is thought to be mediated predominantly through a hypothalamic pathway, it seems likely that melatonin facilitates GH secretion at a hypothalamic level.
有证据表明褪黑素可能在调节垂体分泌中起作用，尽管其机制尚不清楚。我们研究了单次口服褪黑素（5毫克）对运动诱导的生长激素（GH）分泌的影响。在一项随机、双盲、安慰剂对照研究中，七名健康男性受试者进行了初始阶段的分级自行车测力计运动，以确定最大工作量和摄氧量（VO₂max）。受试者随后在另外两个场合接受研究，在每次研究开始时（-60分钟）随机接受褪黑素或安慰剂。在0分钟时，以相当于VO₂max时所达到工作量的70%进行8分钟的自行车运动。从研究开始到运动后120分钟，每隔15分钟测量血清GH和胰岛素样生长因子结合蛋白-1（IGFBP-1）浓度。还采集血样以测量血浆葡萄糖、胰岛素、非酯化脂肪酸、IGFBP-3、褪黑素和血管加压素浓度。与安慰剂相比，褪黑素后运动诱导的GH浓度增加更大，通过曲线下面积（P<0.01）和GH水平的峰值增加（P<0.01）评估均是如此。与安慰剂相比，褪黑素后运动后IGFBP-1水平的峰值增加也显著更大（P<0.01），但通过曲线下面积测量未完全达到显著水平（P=0.07）。由于运动诱导的GH分泌被认为主要通过下丘脑途径介导，褪黑素似乎可能在下丘脑水平促进GH分泌。
