高原缺氧对西藏藏族骨骼肌含量、功能和少肌症的影响

Sarcopenia caused by ageing has been a serious problem that influences the elderly health and quality of life, not only leading to the decrease daily activities of the elderly but also causing a variety of age-related diseases. Many studies showed that the changes of skeletal muscle mass and function during aging were very similar to that in hypoxic environment. Some researchers considered that hypoxia may been the main reason of sarcopenia, but the mechanism remained unknown. Plenty of evidence showed that the endocrine system and genetic adaptation would been affected by hypoxia. The present study is conducted to analyze the effect of endocrine system and genetic adaptation on skeletal muscle mass and function of Tibetans living in hypoxic plateau, to explore the possible roles of hypoxia in the pathogenesis of sarcopenia. Meanwhile, the diagnostic criteria for sarcopenia should consider racial and national differences. Affected by environmental and racial factors, the domestic diagnostic criteria of sarcopenia may be inapplicable to Tibetans. The present study is aimed to analyze the skeletal muscle mass and function, to determine the diagnostic criteria for sarcopenia of Tibetans.The above research not only provides effective evidence for the role of hypoxia in the pathogenesis of sarcopenia , but also provides a reference for diagnosis, prevention and treatment of sarcopenia in Tibetans.

增龄导致的少肌症不仅使老年人日常活动能力下降，还可诱发多种老年性疾病，已成为影响老年人健康和生活质量的严重问题。研究表明，在衰老过程中，骨骼肌结构和功能的变化与在缺氧环境下的变化有很大的相似性。有学者认为缺氧可能是衰老过程中少肌症发生的主要原因，但具体机制不明。很多证据表明：高原缺氧会对内分泌系统和遗传适应产生影响。本项目通过分析内分泌系统、遗传因素对高原缺氧环境下生活的藏族人骨骼肌含量和功能的影响，探讨缺氧在少肌症发生中的作用及可能机制。同时，学术界认为少肌症诊断标准应该具有广泛的种族和民族代表性。受环境和种族双重因素影响，国内现有的少肌症诊断标准不一定适用于藏族人群。本项目通过对藏族骨骼肌含量和功能进行调查，以确定适合藏族人的少肌症诊断标准。通过以上研究，不仅能为研究缺氧在少肌症发生中的作用提供有效证据，还可以为藏族少肌症的诊断、预防和治疗提供依据。

本课题按照亚洲少肌症工作组推荐的方法，对不同海拔高度的 3 个藏族人群（拉萨、那曲、日喀则）和 2 个汉族人群（锦州、拉萨）步速、握力和体成分指标进行测定，确定藏族和锦州汉族少肌症的诊断标准和发病情况。同时为获得少肌症的影响因素，利用化学发光法等检测性激素等14个血清学指标、PCR 和Sanger测序法分析ACTN3等8个基因位点的多态性、问卷调查生活方式等111项基本情况。共获得有效样本4741例，血样1887例。结果表明：（1）缺氧对人的肌肉量、脂肪量、推定骨量、身体水分等有影响，海拔越高，各项指标越低；（2）藏族少肌症的诊断参考值不同于平原人群，藏族少肌症的发病率男性34.1%、女性34.6%，显著高于平原汉族；（3）藏族少肌症的发生与性激素水平等有关。在男性,血清镁水平、睾酮水平是少肌症发病的危险因素；在女性，血清镁水平是少肌症发病的危险因素；（4）少肌症的发病受遗传因素的影响。CNTF基因G1357A、ACE基因I/D、IGF-1基因（CA）n、TRHR基因 rs16892496和VDR基因rs2228570（Fokl）多态位点均可作为西藏藏族人少肌症的分子遗传学标记；（5）性别、年龄、肌肉量、骨密度均与藏族跌倒风险有关，男性左上肢肌肉量、女性右下肢肌肉含量是跌倒风险的保护因素；（6）绝经可导致藏族女性肌肉量和蛋白质减少，脂肪量、体重和BMI增加，并且增加骨质疏松的发病率。综上，平原人群的少肌症诊断参考值不适用于高原人群，高原人群应根据海拔高度确定适合本人群的少肌症诊断参考值，缺氧、性激素、血清离子水平、遗传因素、生理状态对少肌症的发病有一定影响，本研究确定的少肌症诊断参考值对于高原人群少肌症的诊断和预防具有重要意义。