Misra Madhusmita, Bredella Miriam A, Tsai Patrika, Mendes Nara, Miller Karen K, Klibanski Anne
Neuroendocrine Unit and Pediatric Endocrine Unit, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114, USA.
Am J Physiol Endocrinol Metab. 2008 Aug;295(2):E385-92. doi: 10.1152/ajpendo.00052.2008. Epub 2008 Jun 10.
Although body composition, insulin sensitivity, and lipids are markedly altered in overweight adolescents, hormonal associations with these parameters have not been well characterized. Growth hormone (GH) deficiency and hypercortisolemia predispose to abdominal adiposity and insulin resistance, and GH secretion is decreased in obese adults. We hypothesized that low-peak GH on the GH-releasing hormone (GHRH)-arginine stimulation test and high cortisol in overweight adolescents would be associated with higher regional fat, insulin resistance, and lipids. We examined the following parameters in 15 overweight and 15 bone age-matched control 12- to 18-yr-old girls: 1) body composition using dual-energy X-ray absorptiometry and MR [visceral and subcutaneous adipose tissue at L(4)-L(5) and soleus intramyocellular lipid ((1)H-MR spectroscopy)], 2) peak GH on the GHRH-arginine stimulation test, 3) mean overnight GH and cortisol, 4) 24-h urinary free cortisol (UFC), 5) fasting lipids, and 6) an oral glucose tolerance test. Stepwise regression was the major tool employed to determine relationships between measured parameters. Log peak GH on the GHRH-arginine test was lower (P = 0.03) and log UFC was higher (P = 0.02) in overweight girls. Log mean cortisol (overnight sampling) was associated positively with subcutaneous adipose tissue and, with body mass index standard deviation score, accounted for 92% of its variability, whereas log peak GH and body mass index standard deviation score accounted for 88% of visceral adipose tissue variability and log peak GH for 34% of the intramyocellular lipid variability. Log mean cortisol was independently associated with log homeostasis model assessment of insulin resistance, LDL, and HDL and explained 49-59% of the variability. Our data indicate that lower peak GH and higher UFC in overweight girls are associated with visceral adiposity, insulin resistance, and lipids.
尽管超重青少年的身体成分、胰岛素敏感性和血脂有显著改变，但激素与这些参数之间的关联尚未得到充分描述。生长激素（GH）缺乏和高皮质醇血症易导致腹部肥胖和胰岛素抵抗，且肥胖成年人的GH分泌减少。我们推测，超重青少年在生长激素释放激素（GHRH）-精氨酸刺激试验中GH峰值低以及皮质醇水平高与更高的局部脂肪、胰岛素抵抗和血脂有关。我们检测了15名超重的12至18岁女孩和15名骨龄匹配的对照女孩的以下参数：1）使用双能X线吸收法和磁共振成像测量身体成分[L(4)-L(5)水平的内脏和皮下脂肪组织以及比目鱼肌细胞内脂质（(1)H-磁共振波谱法）]，2）GHRH-精氨酸刺激试验中的GH峰值，3）夜间平均GH和皮质醇，4）24小时尿游离皮质醇（UFC），5）空腹血脂，6）口服葡萄糖耐量试验。逐步回归是用于确定测量参数之间关系的主要工具。超重女孩在GHRH-精氨酸试验中的对数GH峰值较低（P = 0.03），对数UFC较高（P = 0.02）。对数平均皮质醇（夜间采样）与皮下脂肪组织呈正相关，并且与体重指数标准差得分一起，解释了其变异性的92%，而对数GH峰值和体重指数标准差得分解释了内脏脂肪组织变异性的88%，对数GH峰值解释了细胞内脂质变异性的34%。对数平均皮质醇与胰岛素抵抗、低密度脂蛋白和高密度脂蛋白的对数稳态模型评估独立相关，并解释了49 - 59%的变异性。我们的数据表明，超重女孩中较低的GH峰值和较高的UFC与内脏肥胖、胰岛素抵抗和血脂有关。
