高温对尾吊大鼠运动耐力及血清睾酮和皮质醇水平的影响

Effects of Heat Stress on Exercise Tolerance,Serum Testosterone and Cortisol Concentrations in Tail-suspended Rats.

目的探讨高温对尾吊大鼠运动耐力的影响及蛋白质代谢在耐力变化中的作用。方法46只雄性SD大鼠,随机分为对照组、尾吊组、高温组和尾吊后高温组。大鼠对照饲养或尾吊14d后,在正常或38℃环境中进行力竭性运动。测定大鼠的力竭时间、大鼠运动后肛温增值和力竭即刻血清睾酮、皮质醇含量。结果与对照组比较,其它3组力竭时间均显著缩短,睾酮含量和睾酮/皮质醇比值均显著降低;尾吊组和高温组皮质醇含量均无显著差异,尾吊后高温组皮质醇含量显著升高。与尾吊组相比,尾吊后高温组的力竭时间、睾酮含量和睾酮/皮质醇比值显著降低;肛温增值和皮质醇含量显著升高。结论高温环境可明显降低尾吊大鼠的运动耐力,并可能与运动过程中体温调节能力下降及蛋白质合成代谢减弱,分解代谢加强有关。

Objective To investigate effects of heat stress on exercise tolerance and functions of protein metabolism the changes in tail-suspended rats. Methods Forty-six male SD rats were randomly assigned to 4 groups： exercise control group （Con）, exercise after tail-suspension group （ES）, exercise under high temperature group （EHT） and exercise under high temperature after tail-suspension group （EHTS）. The rats underwent exercise of increasing intensity until exhaustion under normal or 38 ℃ environment after 14 d of tail suspension or Con. The running time and the increased rectal temperature after exercise were measured at the end of exhaustion. Blood samples were collected immediately after exercise to detect serum testosterone and cortisol concentrations. Results As compared with Con rats, the running time, serum testosterone concentrations and testosterone/cortisol ratio of ES rats, EHT and EHTS rats decreased significantly. As compared with Con rats, the serum cortisol concentrations showed no significant change in ES and EHT rats, and the concentrations increased significantly in EHTS rats. Running time, serum testosterone concentra- tions and testosterone/cortisol ratio of EHTS rats were significantly shorter or lower when compared with those of ES rats. The increases of rectal temperature and serum cortisol concentrations in EHTS rats were significantly higher than those in ES rats. Conclusion Thermal stress（38 ℃） sig- nificantly decreases the exercise tolerance of tail-suspended rats, which might be related to the decrease of thermoregulation capability, intensification of catabolism and attenuation of anabolism.