运动疲劳状态下大鼠脑皮层单羧酸转运蛋白表达的变化及意义

Expression and Significance of Monocarboxylate Transporters in Cortex of Rats After Exercise-induced Fatigue

目的探讨机体对运动疲劳的适应性与大脑皮层单羧酸转运蛋白(monocarboxylate transporters,MCTs)表达变化的关联性。方法 42只清洁级SD大鼠随机均分为对照组和疲劳1~6组。疲劳1~6组大鼠分别进行跑台负荷力竭运动1、3、5、7、9、14 d,建立运动疲劳模型。首先记录各疲劳组大鼠达到力竭状态的平均时间,确定大鼠运动疲劳的变化趋势。随后利用蛋白质印迹和免疫荧光双标法检测各组大鼠脑运动区皮层MCT1、MCT2和MCT4的表达变化。结果运动5 d后疲劳3组大鼠运动力竭时间达到最短[(67.00±7.07) min],运动9 d后恢复至(89.17±9.45) min,二者差异有统计学意义(P<0.05);此后大鼠运动能力基本维持恒定。蛋白质印迹法检测提示,对照组大鼠运动区皮层MCT1、MCT2及MCT4均少量表达;运动5 d后,疲劳3组MCT2表达相比对照组升高74.2%(P<0.05);运动7 d后,疲劳4组MCT1和MCT2表达相比对照组升高89.5%和92.0%(P<0.05);此后鼠脑MCT1、MCT2及MCT4维持高表达状态。免疫荧光与蛋白质印迹法检测结果相一致。结论脑皮层MCTs表达增加所代表的脑乳酸代谢调控与机体对运动疲劳产生的适应性相关联,可能是运动疲劳医学干预的靶点。

Objective To explore the correlation between the adaptation of the body to exerciseinduced fatigue and the expression of monocarboxylate transporters(MCTs) in the cerebral cortex.Methods A total of 42 SD rats were randomly divided into control group and fatigue group 1 to 6. Firstly,the average exhaustive times in each fatigue group were recorded to determine the trend of exerciseinduced fatigue after 1, 3, 5, 7, 9 and 14 days exhaustive load treadmill exercises respectively. Subsequently,the changes of MCT1, MCT2 and MCT4 expression in cerebral motor cortex of rat brain were detected by Western blotting and double-labeling immunofluorescence. Results After 5 days of exercise, the average exhaustive time of rats in fatigue of group 3 reached the lowest level [(67.00±7.07) min] and it recovered to(89.17±9.45) min after 9 days of exercise, the difference was statistically significant(P<0.05). After that, the exercise ability of the rats remained basically constant. Western blotting analysis showed a small amount of MCT1, MCT2 and MCT4 normal expression in cerebral motor cortex of rats’ brain in control group. After 5 days of exercise, the expression levels of MCT2 in fatigue of group 3 were significantly increased by 74.2%compared with the control group(P<0.05). After 7 days of exercise, the expression levels of MCT1 and MCT4 in fatigue of group 4 were significantly increased by 89.5% and 92.0% compared with the control group(P<0.05). After that, MCT1, MCT2, and MCT4 maintained high expression. The results of immunofluorescence were consistent with those of Western blotting. Conclusion The regulation of cerebral lactic acid metabolism represented by the increased expression of MCTs in the cerebral cortex is related to the adaptation of the body to exercise-induced fatigue, which can be used as a target for exercise-induced fatigue medical intervention.