【作者】 黄丽敏；

【导师】 赵斌；

【作者基本信息】 河北师范大学 ， 体育教育训练学， 2010， 博士

【摘要】 世界人口的老龄化已经成为许多国家需要面对的突出的社会问题。面对快速增长的老年人口,如何延长老年人的健康寿命,提高老年人的生活质量得到各国政府和社会各界的高度关注。预防衰老和延缓衰老已成为当前老年医学领域中的研究热点。近年来研究发现,老年人生活质量的下降与肌肉力量的下降有着重要的联系,老年人骨骼肌功能的衰退会加速人体整体的衰老进程,因此延缓骨骼肌衰老和恢复骨骼肌功能对提高老年人的健康水平和生活质量具有十分重要的意义。运动作为抗衰老手段和方法,已被诸多的研究所证实。但就如何预防和延缓由衰老引起的骨骼肌质量的减小和力量的衰退,科研人员正在进行积极探索。相关的研究多以有氧运动或短期力量训练为主,对骨骼肌刺激更明显的长期抗阻力量训练或负重训练的研究较少,并且缺少运动抗骨骼肌衰老的机理及综合指标的研究,作用效果也有待于进一步探索。本研究通过测量和比较大鼠骨骼肌腓肠肌重量及相对重量、骨骼肌总蛋白、肌糖原、肌酸激酶含量,骨骼肌组织病理学和电镜观察,运用分子生物学技术检测机械生长因子(MGF)、骨骼肌肌动蛋白(α-actin)、肌球蛋白重链(MHCⅠ、MHCⅡa、MHCⅡb、MHCⅡx)mRNA等指标,探讨大鼠骨骼肌增龄变化特点以及负重训练对青年大鼠和老年大鼠的影响,进一步揭示适宜的负重训练在预防和延缓骨骼肌衰老中的作用机制,为指导中老年人科学的健身,合理进行力量训练,提高健康水平和生活质量,提供实验依据和理论参考。实验分为三部分:一、大鼠骨骼肌增龄变化的特征及MGF基因表达的实验研究5月龄雄性Wistar健康大鼠6只(Q),17月龄大鼠6只(Z),30月龄大鼠6只(L),所有大鼠取完整腓肠肌,比较各组腓肠肌重量与相对重量、骨骼肌组织切片、电镜观察、骨骼肌组织生化以及分子生物学指标,探讨大鼠骨骼肌增龄变化特征及MGF基因随增龄表达的变化特点二、负重跑台训练对青年大鼠骨骼肌的作用效果及MGF基因表达的实验研究3月龄雄性Wistar健康大鼠56只,随机分为7组:安静对照组(QD)、小负荷短时间组(XD)、小负荷长时间组(XC)、中负荷短时间组(ZD)、中负荷长时间组(ZC)、大负荷短时间组(DD)、大负荷长时间组(DC),除对照组外其他各组进行为期8周负重跑台训练。8周后处死大鼠,测试指标同实验一,探讨负重跑台训练对青年大鼠骨骼肌的作用效果及MGF基因表达的变化。三、负重跑台训练对老年大鼠骨骼肌的作用效果及MGF基因表达的实验研究15月龄雄性Wistar健康大鼠56只,随机分为7组:安静对照组(LD)、小负荷短时间组(LXD)、小负荷长时间组(LXC)、中负荷短时间组(LZD)、中负荷长时间组(LZC)、大负荷短时间组(LDD)、大负荷长时间组(LDC),除对照组外其他各组进行为期8周负重跑台训练。8周后处死大鼠,测试指标同实验一,探讨负重跑台训练对老年大鼠骨骼肌的作用效果及MGF基因表达的变化。结果如下:1.腓肠肌重量与相对重量:L组和Z组大鼠腓肠肌总重量和相对重量均显著低于Q组(P<0.01),L组与Z组相比,L组大鼠显著下降(P<0.01);负重跑台训练使青年大鼠和老年大鼠各组腓肠肌总重量和相对重量普遍增高,说明骨骼肌质量随增龄而减少,负重跑台训练可以提高骨骼肌质量。2.骨骼肌组织生化指标:与Q组相比,L组和Z组大鼠骨骼肌蛋白、肌糖原、肌酸激酶含量出现显著下降(P<0.01或P<0.05)。负重跑台训练使青年大鼠和老年大鼠各组骨骼肌蛋白、肌糖原、肌酸激酶含量出现增高趋势。青年组以DC和ZC组最为显著(P<0.05),老年组以LZC最为显著(P<0.05),说明骨骼肌蛋白、肌糖原、肌酸激酶含量随增龄而减少,负重跑台训练可以提高骨骼肌蛋白、肌糖原、肌酸激酶含量。3.骨骼肌组织切片:光镜下观察Q组大鼠为正常骨骼肌组织学特征,L组和Z组出现不同程度的肌细胞萎缩或退行性改变特征,以L组变化最为明显。负重跑台训练使青年大鼠和老年大鼠骨骼肌组织学特征发生变化,提示负重跑台训练可以改善大鼠骨骼肌细胞形态结构,延缓大鼠骨骼肌衰老进程。4.骨骼肌组织电镜观察:电镜下观察Q组大鼠为正常骨骼肌超微结构,L组和Z组出现不同程度的肌原纤维排列异常和细胞器退行性改变特征,以L组变化最为明显。负重跑台训练使青年大鼠和老年大鼠骨骼肌超微结构发生变化,说明负重跑台训练可以改善大鼠骨骼肌超微结构,延缓大鼠骨骼肌衰老。5.骨骼肌组织分子生物学指标:与Q组相比,L组和Z组大鼠骨骼肌MGF mRNA、α-actin mRNA、MHCⅡa mRNA、MHCⅡxmRNA表达显著减少(P<0.01),MHCⅠmRNA表达没有明显变化,MHCⅡbmRNA表达显著增加(P<0.01)。负重跑台训练使青年大鼠和老年大鼠骨骼肌MGF mRNA、α-actin mRNA、MHCⅠmRNA、MHCⅡa mRNA、MHCⅡxmRNA表达出现增高趋势,青年组以DC和ZC组最为显著(P<0.01),老年组以LZC组最为显著(P<0.01)。MHCⅡbmRNA表达显著减少(P<0.01),青年组以DC和ZC组最为显著(P<0.01),老年组以LZC组最为显著(P<0.01)。说明随年龄增加骨骼肌MGFmRNA表达显著减少,负重跑台训练可以促进骨骼肌MGFmRNA表达增加,并使α-actin、MHC各型mRNA的表达发生变化。结论: 1.增龄使大鼠骨骼肌生化指标、微观结构和分子指标表现出递减趋势,伴随增龄MGF mRNA表达显著减少,骨骼肌合成代谢降低,骨骼肌功能下降。2. 8周负重跑台训练可以有效改善大鼠骨骼肌生化指标、病理学指标和分子生物学指标。不同的负荷和时间所起到的效果不同,青年大鼠以大负重长时间训练效果最好,老年大鼠以中等负荷长时间训练效果最好。3.对老年大鼠进行不同负荷和时间的负重训练,通过检测α-actin、MHCⅠ、Ⅱa、Ⅱx和Ⅱb mRNA的表达,显示老年骨骼肌具有明显的锻炼可塑性,适宜的强度和时间进行训练,可有效改善骨骼肌的收缩蛋白代谢。4.负重训练改善增龄大鼠骨骼肌的结构和功能,延缓老年大鼠骨骼肌衰老可能机制:MGF作为对力量训练敏感指标,可通过适宜的力的刺激,激活MGF的表达,从而通过诱导骨骼肌肥大等途径提高骨骼肌代谢水平和运动能力。更多还原

【Abstract】 The aging of the word’s population has become prominent social problems in many countries. In the face of the rapidly growing elderly population, how to extend the life of the elderly and improve the quality of the elderly have been great concern by the governments and the community. The prevention of aging and anti-aging has become hotspot research in gerontology. Recent studies have found that there have been important links between the decline of life quality and decline of muscle strength of the elderly. The decay of muscle function accelerate the aging process of human body, so it is very important of slowing down skeletal muscle aging and restoring skeletal muscle to improve the health and life quality of the elderly.Many researches have confirmed that exercise is methods of anti-aging, but the researchers actively explored how to prevent and delay the decrease of skeletal muscle mass and strength decline which were caused by the aging. The most research are about aerobic and short term strength training, the patterns of long resistance and weight training which are effective to the skeletal muscle are lack, especially be short of researches in mechanism and comprehensive index of exercise interference skeletal muscle aging, and the effect also need to be further research.In the study, measuring and comparing gastrocnemius muscle weight, relative weight, muscle total protein, muscle glycogen, creatine kinase, muscle histopathology and electron microscopy, mechanical growth factor, actin, myosin heavy chain mRNA, we discuss the age-related changes of rat skeletal muscle and effect of weight training on young and aged rats, reveal further the mechanism of appropriate weight training in the prevention and delay skeletal muscle aging, to provide experimental evidence and theoretical reference to guide the science fitness and improve health and quality life.Experiment was divided into three parts.1. Experiment of age-related changes and MGF gene expression of rat skeletal musclesix 5 month (Q), six 17 month (Z), six 30 month (L) male Wistar rats were taken full gastrocnemius to compare the weight and relative weight, skeletal muscle biopsy, electron microscopy, molecular biology index of three groups, in order to explore the characteristics of age-related changes and MGF gene expression of rat skeletal muscle.2. Experiment of the effect of weighting training and MGF gene expression on young rat skeletal muscleFifty-six 3 month male Wistar rats were randomly divided into 7 groups: sedentary control group (QD), small load short time group (XD), small load long time group (XC), middle load short time group (ZD), middle load long time group (ZC), big load short time group (DD), and big load long time group (DC). Except sedentary control group, other groups had done weight treadmill training. After 8 weeks, all rats were killed, indicators were the same with experimental 1, and we discussed the effect of weight training on young rat skeletal muscle and MGF gene expression changes.3. Experiment of the effect of weighting training and MGF gene expression on young rat skeletal muscleFifty-six 15 month male Wistar rats were randomly divided into 7 groups: sedentary control group (LD), small load short time group (LXD), small load long time group (LXC), middle load short time group (LZD), middle load long time group (LZC), big load short time group (LDD), and big load long time group (LDC). Except sedentary control group, other groups had done weight treadmill training. After 8 weeks, all rats were killed, indicators were the same with experimental 1, and we discussed the effect of weight training on old rat skeletal muscle and MGF gene expression changes.Results1. Gastrocnemius muscle weight and the relative weight: compared with group Q, rat gastrocnemius muscle weight and the relative weight in group L and group Z were significantly higher(P<0.01); Compared with group Z, group L were significantly lower(P<0.01). Weight treadmill training increased gastrocnemius muscle weight and the relative weight in all young groups rats and old groups rats. Results indicated that skeletal muscle mass decreased with age, and weight treadmill training can alleviate the trend.2. Skeletal muscle biochemical indicators: compared with group Q, skeletal muscle protein, muscle glycogen, creatine kinase level significantly decreased in group L and group Z (P<0.01, P<0.05). Weight treadmill training could increase skeletal muscle protein, muscle glycogen, creatine kinase level of all young and old groups , group DC and group ZC had more obvious appearance in young rats (P<0.05), group LZC had more obvious appearance in old rats (P<0.05). Result indicated that skeletal muscle protein, muscle glycogen, creatine kinase level decreased with age, and weight treadmill training could alleviate the trend.3. Skeletal muscle biopsy: rats in group Q were normal skeletal muscle characteristics through light microscope, and group L and group Z appeared different degree of muscle cell atrophy or degenerative changes characteristics, especially the rats in group L. Weight training changed the skeletal muscle histology characteristics of young rats and old rats. Result indicated that weight training changed skeletal muscle cell morphology and slowed down skeletal muscle aging.4. Skeletal muscle electron microscopy: rats in group Q were normal skeletal muscle ultrastructure through electron miscroscopy, and group L and group Z appeared different degree of abnormal arrangement myofibrils and organelles degenerative changes characteristic, especially the rats in group L. Weight training changed the skeletal muscle ultrastructure of young rats and old rats. Result indicated that weight training changed skeletal muscle ultrastructure and slowed down skeletal muscle aging.5. Skeletal muscle molecular biological markers: compared with group Q, skeletal muscle MGF mRNA、α-actin mRNA、MHCⅡa mRNA、MHCⅡx mRNA expression in group L and group Z were lower (P<0.01), MHCⅠmRNA expression did not change, and MHCⅡb mRNA expression was higher (P<0.01). Weight training could increase MGF mRNA、α-actin mRNA、MHCⅠmRNA、MHCⅡa mRNA、MHCⅡx mRNA expression of young rats and old rats, group DC and group ZC had more obvious appearance in young rats (P<0.01), and group LZC had more obvious appearance in old rats (P<0.01). It could decrease MHCⅡb mRNA expression (P<0.01), group DC and group ZC had more obvious appearance in young rats (P<0.01), and group LZC had more obvious appearance in old rats (P<0.01). Result indicated that skeletal muscle MGF mRNA expression decreased with aging, but weight training increased skeletal MGF mRNA expression, and changeα-actin, various types MGF mRNA expression. Conclusion1. Rats skeletal muscle biochemical indicators, microscopic structure, and molecular indicators showed degression trend, MGF mRNA expression was significant low, anabolism reduced and function decreased with ageing.2. 8-week weight training could effective improve skeletal muscle biochemical indicators, pathological indicators and molecular biological indicators. The effect of different load and time on skeletal muscle was different, big load long time group had more appearance in young rats, and middle load long time group had more appearance in old rats.3. After different load and time weight training,α-actin、MHCⅠ、Ⅱa、Ⅱx andⅡb mRNA expression of old rat skeletal muscle were tested, we founded that aged skeletal muscle had obvious trainability, and proper intensity and time training could effectively improve skeletal muscle protein metabolism.4. Weight training improved structure and function of aging skeletal muscle, and delayed skeletal muscle aging. Its mechanism: MGF as a sensitive indicator was stimulated to express by appropriate force, which improved skeletal muscle metabolic level and athletic ability through some channels such as induced skeletal muscle hypertrophy.更多还原