Abou Samra Rania, Baba Nahla Hwalla, Torbay Naji, Dib Lea, El-Hajj Fuleihan Ghada
Department of Nutrition and Food Science, American University of Beirut, Beirut, Lebanon 113-6044.
J Clin Endocrinol Metab. 2005 May;90(5):2588-94. doi: 10.1210/jc.2004-2049. Epub 2005 Feb 15.
Obesity's protective effect on bone density may be mediated through increased muscle mass, fat mass, increased estrogen, and possibly insulin and leptin levels. To determine the impact of leptin and insulin on bone metabolism, we studied 48 obese normally cycling premenopausal women (age, 31 +/- 10 yr; body mass index, 35.7 +/- 5 kg/m2): 28 insulin resistant (IR) and 20 insulin sensitive (IS) by McAuley index. Anthropometric, body composition, and bone mineral density (BMD) measurements were made, and serum leptin, insulin, free testosterone, IGF-I, bone remodeling markers, and calciotropic hormones were measured. Anthropometric, lifestyle, and biochemical markers were similar in the two groups. Despite higher circulating insulin and leptin levels, IR subjects had similar mean values of serum osteocalcin but higher C-telopeptide (P = 0.052). They had similar BMD at all skeletal sites compared with IS subjects. In the IR group, fat mass but not lean mass, serum leptin, insulin, testosterone, and IGF-I levels correlated positively with hip and/or total-body bone density with R varying between 0.38 and 0.65; no correlations were observed at the spine. Conversely, in the IS group, lean mass, but not fat mass, and only IGF-I correlated with hip BMD/total-body bone mineral content. In conclusion, there is a dichotomy in the impact of body composition parameters and insulin and leptin levels on bone parameters in obese individuals. The interaction between the fat-related endocrine system and bone seems to be complex and may be modulated by local resistance to the putative protective effect of insulin and leptin on bone.
肥胖对骨密度的保护作用可能是通过增加肌肉量、脂肪量、雌激素，以及可能通过增加胰岛素和瘦素水平来介导的。为了确定瘦素和胰岛素对骨代谢的影响，我们研究了48名肥胖的、月经周期正常的绝经前女性（年龄31±10岁；体重指数35.7±5kg/m2）：根据麦考利指数分为28名胰岛素抵抗（IR）者和20名胰岛素敏感（IS）者。进行了人体测量、身体成分分析和骨矿物质密度（BMD）测量，并检测了血清瘦素、胰岛素、游离睾酮、胰岛素样生长因子-I（IGF-I）、骨重塑标志物和促钙激素。两组的人体测量、生活方式和生化标志物相似。尽管IR组的循环胰岛素和瘦素水平较高，但其血清骨钙素的平均值与IS组相似，但C-端肽水平较高（P=0.052）。与IS组相比，IR组在所有骨骼部位的骨密度相似。在IR组中，脂肪量而非瘦体重、血清瘦素、胰岛素、睾酮和IGF-I水平与髋部和/或全身骨密度呈正相关，相关系数R在0.38至0.65之间；在脊柱部位未观察到相关性。相反，在IS组中，是瘦体重而非脂肪量，且只有IGF-I与髋部骨密度/全身骨矿物质含量相关。总之，肥胖个体中身体成分参数以及胰岛素和瘦素水平对骨参数的影响存在差异。脂肪相关内分泌系统与骨骼之间的相互作用似乎很复杂，可能会受到局部对胰岛素和瘦素对骨骼假定保护作用的抵抗的调节。
