长期有氧运动训练对老年大鼠主动脉中肾素-血管紧张素系统的影响

摘要

The objective of our work is to investigate the effects of chronic aerobic exercise training on renin-angiotensin system in aortas of aged rats.The rats were randomly divided into three groups as follows:(1) adult group (Adult);(2)aged group (Aged);(3) aged group received exercise (Aged+EX).Chronic aerobic exercise training in aged rats lowered the body weight and activity of citrate synthase in soleus,which demonstrated the efficacy of exercise training in aged rats.Chronic aerobic exercise training in aged rats reduced aortic wall thickness,and prevented aging-related endothelial dysfunction marked by improved endothelium-mediated vascular relaxation of aortas in response to acetylcholine.Chronic aerobic exercise training in aged rats had no significant effect on levels of angiotensin Ⅱ (Ang Ⅱ) or angiotensin-(1-7) (Ang-(1-7)) in plasma,but reduced AngⅡ levels and mRNA expression of angiotensin-converting enzyme (ACE) and enhanced Ang-(1-7) levels and mRNA expression of angiotensin-converting enzyme 2 (ACE2) in aortas.In addition,chronic aerobic exercise training in aged rats down regulated mRNA expression of angiotensin Ⅱ type 1 receptor (AT1R) and upregulated angiotensin Ⅱ type 2 receptor (AT2R) and Mas in aortas.It is concluded that chronic aerobic exercise training improved balance of renin-angiotensin system between ACE/AngⅡ/AT1Rand ACE2/Ang-(1-7)/Mas in aged aortas,which mightpartly explain the improvement of exercise against vascular aging.%目的:探讨长期有氧运动训练对老年大鼠主动脉中肾素-血管紧张素系统的影响.方法:23月龄的老年大鼠分为运动组(Aged+EX)和非运动组(Aged),游泳训练12周之后分离血液和取出胸主动脉用于检测,同时采用6月龄大鼠做为成年对照组(Adult).结果:老年大鼠经过12周运动训练后,与非运动组相比,体质量明显下降,同时比目鱼肌中柠檬酸合酶活性明显增加,这证实了运动训练的有效性.老年大鼠经过运动训练后,主动脉厚度下降,平滑肌细胞增生得到抑制,同时主动脉内皮功能得到部分改善.老年大鼠经过运动训练后,血浆中AngⅡ和Ang-(1-7)水平变化不明显,但是主动脉中AngⅡ水平下降,Ang-(1-7)水平增加;它们相应的生成酶ACE的mRNA水平下降而ACE2的mRNA水平增加.另外发现,运动训练后主动脉中AT1R的mRNA水平下降,而AT2R和Mas的mRNA水平增加.结论:长期有氧运动训练改善了主动脉组织中ACE/AngⅡ/AT1R和ACE2/Ang-(1-7)/Mas两条通路之间的平衡,该机制有助于解释长期有氧运动训练对血管老化的改善作用.