16周HIIT干预对增龄大鼠骨骼肌线粒体自噬、ATP浓度及有氧运动能力的影响

Effects of 16 Weeks HIIT Intervention on Mitochondrial Autophagy,ATP Concentration and Aerobic Exercise Capacity in Skeletal Muscle of Aging Rats

目的:观察增龄和高强度间歇训练(high-intensity interval training,HIIT)干预对大鼠有氧运动能力、骨骼肌线粒体BNIP3、PI3-k相对表达量、线粒体数目、ATP浓度和丙酮酸脱氢酶活性的影响,梳理上述指标与骨骼肌增龄性退变的关系。方法:8月龄SPF级雄性Wistar大鼠40只,按照随机数字表随机.分为安静对照组(C,n=20)和HIIT干预组(H,n=20)。C组不运动,H组以50%、.70%和90%VO_(2max)对应的速度交替进行50 min/天、5天/周、持续16周的运动干预,并根据VO_(2max)测试结果调整运动强度。在基线值(0周)每组各取4只大鼠,在干预的第8、16周结束后的24 h每组各取8只大鼠,剥离大鼠比目鱼肌,采用透射电子显微镜观察线粒体自噬情况,采用比色法检测比目鱼肌线粒体ATP浓度和丙酮酸脱氢酶活性,采用Western blot法测试.BNIP3和PI3-k的蛋白表达。结果:16周增龄过程中,C组递增负荷运动至力竭的时长和VO_(2max)均出现显著降低(P<0.05);H组上述指标在第8周和第16周时均显著高于基线值(P<0.05)。H组比目鱼肌线粒体ATP浓度在16周时显著高于C组和基线值(P<0.05),各组大鼠丙酮酸脱氢酶活性无明显变化。H组线粒体数目在8周和16周时均显著高于C组和基线值(P<0.05),但各组大鼠自噬体数目在组间和组内对比中均未见显著性差异。C组和H组BNIP3在8周和16周时均显著高于基线值(P<0.05)。C组PI3-k在16周时显著高于基线值(P<.0.05),H组PI3-k与基线值未见显著性差异。结论:16周HIIT运动可以提高增龄大鼠的VO_(2max)和有氧运动能力,作用机制或与骨骼肌线粒体数目增加、ATP浓度升高及自噬加强有关。

Objective: To observe the effects of aging and high-intensity interval training(HIIT)intervention on aerobic exercise ability, relative expression levels of BNIP3 and PI3-k in skeletal muscle mitochondria, the number of healthy mitochondria, mitochondrial ATP concentration, pyruvate dehydrogenase activity in rats, and investigate their relationships with aging degeneration of skeletal muscle. Methods: 40 SPF male Wistar rats aged 8 months were selected and randomly divided into a control group(C, n=20) and an HIIT intervention group(H, n=20) according to the random number table. Group C did not exercise, while group H alternated 50 min/day,5 day.s/week, and 16 weeks of exercise intervention at spe.eds corresponding to 50%, 70% and90%VO_(2max), and adjusted exercise intensity according to VO_(2max) test results. Groups of rats in the baseline value(0 week) from each of 4 materials in rats, at the end of the intervention of8 weeks, 16 weeks after 24 h of each 8 only materials, stripping rats’ soleus, the mitochondrial autophagy was observed by transmission electron microscope. The concentration of mitochondrial ATP and the activity of pyruvate dehydrogenase in soleus muscle were measured by colorimetric method, and the protein expressions of BNIP3 and PI3-k were measured by Western blot.Results: During the aging process of 16 weeks, the duration of increasing load movement to exhaustion and V.Oin group C were significantly decreased(P<0.05). The above indexes in group H were significantly higher than the baseline at 8 and 16 weeks(P<0.05). The ATP concentration of soleus mitochondria in group H at 16 weeks was significantly higher than that in group C and the baseline(P<0.05), and there was no significant change in pyruvate dehydrogenase activity in each group. The number of mitochondria in group H at 8 and 16 weeks was significantly higher than that in group C and the baseline(P<0.05), but there was no significant difference in the number of autophagosomes among groups and in intra-group comparison.BNIP3 in groups C and H was significantly higher than the baseline at 8 and 16 weeks(P<0.05). The PI3-k of group C was significantly higher than that of the baseline at 16 weeks(P<0.05), but there was no significant difference between th.e PI3-k of group H and the baseline.Conclusions: 16 weeks of HIIT exercise can improve VO_(2max)and aerobic exercise capacity in aging rats, which may be related to increased number of skeletal muscle mitochondria, increased ATP concentration and enhanced autophagy.