不同强度耐力运动对大鼠心房TGF-β1/miR-21信号途径的影响

Effects of Endurance Exercise of Different Intensity on TGF-β1/miR-21 Signaling Pathpay

目的:通过建立长期大强度运动动物模型,研究不同强度耐力运动对大鼠心房羟脯氨酸含量的影响以及TGF-β1/miR-21信号途径的调节作用,为运动性心房纤颤的发生机制提供实验依据。方法:72只健康成年雄性SD大鼠随机分为安静组、中等强度组和大强度组,每组24只。分别进行8周、12周和16周运动,每周训练5天,休息2天,每次运动1h。运动8周、12周和16周后24h内处死取材摘取心脏,分离出右心房。采用酶联免疫法检测血清cTnI的含量;样本碱水解法检测羟脯氨酸的含量;荧光定量PCR检测TGF-β1和miR-21的含量。Western Blot检测TGF-β1蛋白表达。结果:大强度组8周、12周和16周大鼠血清cTnI的含量均显著高于安静组和中等强度组(P<0.01),中等强度组8周、12周和16周大鼠cTnI的含量均无显著变化。8周运动后,各组之间羟脯氨酸的含量无明显差异;12周和16周大强度组羟脯氨酸的含量显著高于各自的安静组和中等强度组(P<0.01),中等强度组和安静组之间没有显著性差异。随着运动时间延长,大强度组羟脯氨酸的含量有逐渐增加趋势,16周羟脯氨酸的含量显著高于8周大强度组(P<0.05)。8周、12周和16周大强度组TGF-β1基因和蛋白的表达均显著高于各自安静组,而中等强度组和安静组之间TGF-β1的表达无明显差异。随着运动时间延长,大强度组TGF-β1的含量有逐渐降低的趋势。8周、12周和16周运动后,与各自安静组相比,大强度组miR-21的表达均显著性增加(P<0.05),随着运动时间延长,大强度组miR-21的含量有逐渐降低的趋势,16周大强度组miR-21的表达显著低于8周大强度组(P<0.05),中等强度组和安静组之间miR-21的表达无明显差异。结论:长期大强度运动导致大鼠心肌损伤长期存在,并伴随大鼠心房胶原蛋白的持续增加,诱发了心房纤维化,构成了运动性心房纤颤的病理基础。长期大强度运动通过上调大鼠心房TGF-β1/miR-21信号通路,可能介导了运动性心房损伤纤维化的发生。

Objective： To explore effects of different sustained intensive exercise on rat atrial hydroxyproline, and role of TGF- β1 / miR- 21 signaling pathway through establishing longterm exercise animal model, and provide experimental evidence for clarifiying the mechanism of exercise-induced atrial fibrillation. Methods： 72 SD rats were divided into control group （C）, moderate intensity group （M） and high instensity group （H） with 24 animals in each group. M and H group were conditioned to run for 4,8, and 16 weeks, 5 days/weeks, 1h/day. Rats were euthanized to obtain hearts within 24h after exercise. Right atrial were collected, cTnI was quantified by Elisa, hydroxyproline was measured by lkali hydrolysis methodwhich. TGF- 131 and miR-21 gene expression were evaluted by real-time PCR. TGF-β1 protein was quanti fied by Western Blot. Results：Compared with control and M group, rats serum cTnI increased at 8 weeks/12 weeks/16 weeks （P〈0. 01）. While there was no significance between M group and C gourp. There was no significant difference in hydroxyproline at 8 weeks. Compared with C and M group, hydroxyproline content of H group showed significant increase at 12 weeks and 16 weeks （P〈0.01）. No difference was oberserved between C group and M group. Hydroxyproline content of H group confirmed a gradual increase with training time, with significant increase from 8 weeks to 16weeks （P〈0.05）. TGF-β1 gene and protein expression of H group increased compared their control group at 8/12/16 weeks. But no difference was observed between C and M group. TGF-β1 expression had a gradual decrease from 8 to 16 weeks. Compared with their control group,miR-21 expressio of H group showed a significant increase （P〈0.05）. raiR-21 of H group confirmed a gradual decrease with training time, with significant decrease from 8 weeks to 16weeks （P〈0.05）. No significant difference was observed beteen C and M group. Conclusion.. Long-term intensive exercise induced sustained myocardial damage, resulted in sustained collagen increase which induced myocardial fibrosis. This may he a substrate for exercise-induced atrial fibrillation. TGF-β1/miR 21 signa- ling pathway, upregulated by long-term intensive exercise, may involve in the pathology of intense exercise-induced myocardial damage and atrial fibrillation.