Muniyappa Ranganath, Sullivan Shannon D, Tella Sri Harsha, Abel Brent S, Harman S Mitchell, Blackman Marc R
Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland.
Department of Endocrinology, Georgetown University and Washington Hospital Center, Washington, District of Columbia.
Physiol Rep. 2017 Dec;5(23). doi: 10.14814/phy2.13516.
The known interactions between the somatotropic and hypothalamic-pituitary-gonadal (HPG) axes have not been well delineated in older individuals. Aging-associated decline in insulin like growth factor-1 (IGF-1) levels has been proposed to play a role in reproductive senescence in animals. However, the effects of GH on LH secretion are unknown in older individuals. Our objective was to determine whether GH modulates LH secretion or levels of sex steroids (SS) in healthy older (ages 65-88 years) men ( = 24) and women ( = 24) with low-normal plasma IGF-1 levels. In a double-masked, placebo-controlled ( = 24), randomized study, we evaluated the effects of GH ( = 24, 20 g/kg sc 3×/week) for 26 weeks on nocturnal LH secretory dynamics [(8 pm to 8 am, Q20) min sampling and analyzed by multiparameter deconvolution algorithm]. Indices of LH secretion [frequency, mass per burst, pulsatile production rate, and approximate entropy (ApEn)] and fasting serum IGF-1, SHBG, and SS (TT, fT, or E2) were measured. At baseline, all indices of LH secretion (frequency, mass per burst, pulsatile production rate) were inversely ( < 0.05) related to IGF-1, but not to mean nocturnal serum GH concentrations. GH administration for 26 weeks increased serum IGF-1, but exerted no significant effects on LH secretory dynamics, or concentrations of SSs (TT, fT, or E2) or SHBG in older women or men. These data suggest that GH-mediated increases in IGF-1 do not modulate the HPG axis in older individuals.
生长激素轴与下丘脑 - 垂体 - 性腺（HPG）轴之间已知的相互作用在老年人中尚未得到很好的描述。胰岛素样生长因子 -1（IGF -1）水平随衰老而下降被认为在动物生殖衰老中起作用。然而，生长激素（GH）对老年人促黄体生成素（LH）分泌的影响尚不清楚。我们的目的是确定在血浆IGF -1水平处于低正常范围的健康老年男性（n = 24）和女性（n = 24）（年龄65 - 88岁）中，GH是否调节LH分泌或性类固醇（SS）水平。在一项双盲、安慰剂对照（n = 24）的随机研究中，我们评估了GH（n = 24，20μg/kg皮下注射，每周3次）持续26周对夜间LH分泌动态的影响[晚上8点至早上8点，每20分钟采样一次，并通过多参数反卷积算法进行分析]。测量了LH分泌指标[频率、每次脉冲的量、脉冲产生率和近似熵（ApEn）]以及空腹血清IGF -1、性激素结合球蛋白（SHBG）和SS（睾酮（TT）、游离睾酮（fT）或雌二醇（E2））。在基线时，LH分泌的所有指标（频率、每次脉冲的量、脉冲产生率）均与IGF -1呈负相关（P < 0.05），但与夜间血清GH平均浓度无关。给予GH 26周可提高血清IGF -1水平，但对老年女性或男性的LH分泌动态、SS（TT、fT或E2）浓度或SHBG均无显著影响。这些数据表明，GH介导的IGF -1增加在老年人中不会调节HPG轴。
