有氧运动对高脂饮食大鼠窦房结神经及心功能的影响

Effect of Aerobic Exercise on Nervous Remolding in Sinus Node and Cardiac Function of Rats with High Fat Diet

高脂膳食可导致心脏传导系统发生脂肪浸润和纤维化,进而引发心律异常和心血管意外,这些改变可能涉及内源性心脏神经的重塑。为探讨有氧运动对高脂饮食大鼠心功能及心内神经的保护作用,选取8周龄雄性SD大鼠24只,随机分为对照组(C)、高脂组(HF)、有氧运动结合高脂饮食组(FE),各组8只,运动组进行8周的无负重游泳训练,6次/周,1 h/次。多普勒超声测试大鼠心功能,取窦房结进行HE染色,免疫组化检测窦房结神经标志物PGP 9.5以及CGRP和NPY神经递质的表达。结果发现:1)与C组相比,HF组大鼠窦房结心肌纤维排列趋于混乱,神经团块部位存在空泡,窦房结神经纤维丛萎缩,神经元数量减少,有氧运动在一定程度上抑制了窦房结及其神经的结构改变;2)有氧运动改变了窦房结内神经递质分布,使CGRP含量升高,NPY含量降低;3)运动干预引起高脂饮食大鼠心脏射血分数、左心室缩短分数、左心室收缩内经和左心室收缩容积增加,心肌纤维增粗,心脏功能增强。结果说明,高脂饮食可导致大鼠窦房结神经萎缩,心功能下降,有氧运动可通过窦房结神经丛重塑和相关神经递质含量变化发挥对高脂饮食大鼠窦房结结构及心功能的保护作用。

A high fat diet can induce fatty infiltration and fibrosis of the cardiac conduction system,which can disrupt the heart＇s rhythm and lead to cardiac arrest. These changes may involve the remolding of intrinsic cardiac nerve. This study aimed to evaluate the effect of aerobic exercise on the remolding of intrinsic cardiac nerve induced by high fat diet. Methods：Twenty-four male 8-week old Sprague Dawley rats were randomly divided into 3 groups：Control（C）,High fat diet（HF,fat accounted for 45% of kcal）,and High fat diet with Exercise（FE）. FE groups underwent 8-wk of swim training（6 days/week,1 h/day）. Twenty-four hours after the last training,Color Doppler and ECG were used to evaluate heart function on anesthetized rats. Immunohistochemical technique was used to predict the expression of PGP 9.5,CGRP,and NPY in sinus node zone. Group differences were examined using one-way ANOVA and post-hoc comparisons. Results：1） Compared with the group C,nerve tissue in sinus node zone showed vacuolization and atrophy,and neurons decreased in HF group,which is inhibited or reversed to some extent by aerobic exercise;2） Aerobic exercise changes the distribution of neurotransmitters in the sinoatrial node,with increased CGRP and decreased NPY. 3） Aerobic exercise improved the cardiac function in high fat diet rats,with the increased cardiac ejection fraction,left ventricular shortening fraction,left ventricular systolic internal diameter,left ventricular systolic volume,and thickened myocardial fiber. Conclusions：8-week high fat diet can reduce myocardial contractility and heart pumping function,which maybe involve decreasing intracardiac nerve innervation in sinus node area and imbalanced nervous distribution of CGRP and NPY nerves. Regular moderate-intensity aerobic exercise can reverse these nervous remolding to some extent.