热习服对湿热环境运动刺激大鼠大脑皮质和心肌线粒体的影响

Effect of heat acclimation on mitochondrion of cerebral cortex and myocardium in rats stimulated by exercise in hygrothermal environment

目的探究热习服是否能够对湿热环境下进行中高强度运动大鼠的大脑皮质和心肌线粒体结构与功能起保护作用,并探讨其保护机制。方法 40只SD大鼠通过负重力竭实验剔除游泳时间过短和过长的大鼠各4只,剩余32只大鼠随机分成常温自由活动(RA)组、常温运动(RE)组、高温自由活动(HA)组和高温运动(HE)组,每组8只。RA和HA组大鼠分别置于常温[(24±1)℃]和高温[(32±1)℃]条件下自由活动2h/d;RE和HE组大鼠分别置于常温[(24±1)℃]和高温[(32±1)℃]条件下的饲养笼内自由活动1h/d后,在动物跑步机上匀速跑步1h/d(坡度为0°,速度为14m/min);连续训练14d建立热习服大鼠模型。建模后第3天开始,各组大鼠在湿热环境下中高强度运动30min。测量并记录湿热环境下中高强度运动前、后大鼠体质量丢失率、肛温,采用放射免疫法测量血浆去甲肾上腺素(NE)、血管加压素(AVP)和皮质醇(Cort)含量,透射电镜观察运动后大鼠大脑皮质和心肌线粒体的超微结构,ELISA法检测ATP合成酶和活性氧(ROS)含量,总抗氧化能力测试(ABTS)法检测总抗氧化能力。结果 HE组大鼠在湿热环境下中高强度运动后体质量丢失率高于RA组(P<0.01);HE组大鼠运动前、后肛温以及肛温升高幅度均低于RA、RE和HA组(P<0.05,P<0.01)。HE组大鼠运动后血浆中Cort含量低于RA、RE和HA组(P<0.05,P<0.01),大脑皮质和心肌线粒体中ATP合成酶和组织中总抗氧化能力高于RA、RE和HA组(P<0.01),ROS含量低于RA、RE和HA组(P<0.01)。HE组大鼠大脑皮质中线粒体和突触结构以及心肌中线粒体、Z线和横小管的结构优于RA、RE和HA组。结论热习服训练能够增强线粒体氧化呼吸功能、降低细胞的氧化应激水平和血浆中Cort含量,从而保护湿热环境下中高强度运动后大鼠的大脑皮质神经元和心肌细胞线粒体结构。

Objective To explore whether heat acclimation can protect the structure and function of mitochondrion of cerebral cortex and myocardium in rats with moderate and high intensity exercise in hygrothermal environment, and to explore its protective mechanism. Methods Forty SD rats underwent swimming experiment bearing weight and 8 rats were eliminated due to too short-swim or long-swim time. The rest 32 rats were randomly divided into four groups （n=8）; room-temperature activity （RA） group, room-temperature exercise （RE） group, high-temperature activity （HA） group and high-temperature exercise （HE） group. Rats in RA and HA groups were placed at room temperature （[24± 17]℃） and high temperature （[32± 1] ℃） to have a free activity for 2 h/d. Rats in RE and HE groups were placed at room temperature （[24± 1]℃） and high temperature （[32± 1]℃） to have a free activity for 1 h/d and then were allowed to run at a constant speed on the animal treadmill for 1 h/d （slope： 0°, speed： 14 m/min）. After 14 days the heat acclimation rat models were created. Rats in all groups underwent moderate and high intensity exercise in hygrothermal environment for 30 min on the 3rd day. The body weight loss rate and rectal temperatures of rats were measured before and after high and medium intensity exercise in hygrothermal environment. The contents of plasma norepinephrine （NE）, arginine vasopressin （AVP） and cortisol （Cort） in rats were detected by radioimmuaoassay. The ultrastructure of the mitochondria of cerebral cortex and myocardium was observed by transmission electron microscopy. The contents of ATP synthase and reactive oxygen species （RIDS） were detected by ELISA method and the total antioxidative capacity was measured by ABTS method. Results the ascending range of recta] temperatures of rats in HE group HA groups （P 〈 0. 05, P 〈 0. 01）. After stimulation with The rectal temperatures before and after stimulation and were significantly lower than those in the RA, RE and moderate and high intensity exercise in hygrothermal environment, the body weight loss rate of rats in HE group was significantly higher than that in RA group （P〈0. 01）, the contents of plasma Cort and ROS of rats in HE group were significantly lower than those in the RA, RE and HA groups （P〈0. 05. P〈0. 01）, the content of ATP synthase in mitochondrion and total antioxidative capacity in tissue from cerebral cortex and myocardium of rats in HE group were significantly higher than those in the RA, RE and HA groups （P〈0.0I）, and the mitochondrion and synaptic structures m the cerebral cortex and the structures of myoeardium, Z line and transverse tubule in the myoeardium in HE group were superior to those in the RA, RE and HA groups. Conclusion Heat acclimation can enchance the oxidative and respiratory function of mitochondria and reduce the level of ceil oxidative stress and the content of plasma Cort, so as to protect the mitochondrial structure of cerebral cortical neurons and cardiomyocytes in rats with moderate and high intensity exercise in hygrothermal environment.