Muniyappa Ranganath, Sorkin John D, Veldhuis Johannes D, Harman S Mitchell, Münzer Thomas, Bhasin Shalender, Blackman Marc R
Endocrine Section, Laboratory of Clinical Investigation, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, Maryland, USA.
Am J Physiol Endocrinol Metab. 2007 Sep;293(3):E769-75. doi: 10.1152/ajpendo.00709.2006. Epub 2007 Jun 5.
Circulating testosterone (T) and GH/IGF-I are diminished in healthy aging men. Short-term administration of high doses of T augments GH secretion in older men. However, effects of long-term, low-dose T supplementation on GH secretion are unknown. Our objective was to evaluate effects of long-term, low-dose T administration on nocturnal GH secretory dynamics and AM concentrations of IGF-I and IGFBP-3 in healthy older men (65-88 yr, n = 34) with low-normal T and IGF-I. In a double-masked, placebo-controlled, randomized study we assessed effects of low-dose T supplementation (100 mg im every 2 wk) for 26 wk on nocturnal GH secretory dynamics [8 PM to 8 AM, Q(20) min sampling, analyzed by multiparameter deconvolution and approximate entropy (ApEn) algorithms]. The results were that T administration increased serum total T by 33% (P = 0.004) and E(2) by 31% (P = 0.009) and decreased SHBG by 17% (P = 0.002) vs. placebo. T supplementation increased nocturnal integrated GH concentrations by 60% (P = 0.02) and pulsatile GH secretion by 79% (P = 0.05), primarily due to a twofold increase in GH secretory burst mass (P = 0.02) and a 1.9-fold increase in basal GH secretion rate (P = 0.05) vs. placebo. There were no significant changes in GH burst frequency or orderliness of GH release (ApEn). IGF-I levels increased by 22% (P = 0.02), with no significant change in IGFBP-3 levels after T vs. placebo. We conclude that low-dose T supplementation for 26 wk increases spontaneous nocturnal GH secretion and morning serum IGF-I concentrations in healthy older men.
健康老年男性体内循环睾酮（T）以及生长激素/胰岛素样生长因子-I（GH/IGF-I）水平会降低。短期给予老年男性高剂量睾酮可增加其生长激素分泌。然而，长期低剂量补充睾酮对生长激素分泌的影响尚不清楚。我们的目的是评估长期低剂量给予睾酮对健康老年男性（65 - 88岁，n = 34）夜间生长激素分泌动态以及胰岛素样生长因子-I（IGF-I）和胰岛素样生长因子结合蛋白-3（IGFBP-3）上午浓度的影响，这些老年男性的睾酮和IGF-I水平略低于正常范围。在一项双盲、安慰剂对照、随机研究中，我们评估了低剂量睾酮补充剂（每2周肌肉注射100 mg）持续26周对夜间生长激素分泌动态的影响[晚上8点至上午8点，每20分钟采样一次，通过多参数反卷积和近似熵（ApEn）算法进行分析]。结果显示，与安慰剂相比，给予睾酮使血清总睾酮水平升高了33%（P = 0.004），雌二醇（E₂）升高了31%（P = 0.009），性激素结合球蛋白（SHBG）降低了17%（P = 0.002）。补充睾酮使夜间生长激素整合浓度升高了60%（P = 0.02），脉冲式生长激素分泌升高了79%（P = 0.05），这主要是由于与安慰剂相比，生长激素分泌脉冲量增加了两倍（P = 0.02），基础生长激素分泌率增加了1.9倍（P = 0.05）。生长激素脉冲频率或生长激素释放的有序性（ApEn）没有显著变化。与安慰剂相比，给予睾酮后IGF-I水平升高了22%（P = 0.02），IGFBP-3水平没有显著变化。我们得出结论，在健康老年男性中，持续26周低剂量补充睾酮可增加夜间自发性生长激素分泌以及早晨血清IGF-I浓度。
