运动疲劳大鼠可能通过海马LTP抑制及CaN蛋白表达增多降低学习记忆功能

Exercise-induced Fatigue May Reduce Learning and Memory Function through the Inhibition of LTP and the Increased Expression of CaN in Hippocampus

目的:通过观察运动疲劳对大鼠学习记忆、海马CA1区长时程增强(LTP)效应和钙神经素(CaN)蛋白表达的影响,探讨运动疲劳影响学习记忆功能的生理机制。方法:32只健康雄性8周鼠龄SD大鼠,随机分为安静对照组(CG)和运动疲劳组(FG),每组16只。运动疲劳组做连续7天递增负荷跑台运动,每天运动至力竭,对照组不加干预。7天建模结束后,运用避暗穿梭实验检测2组大鼠学习记忆能力,并分别采用在体脑立体定位—神经电生理方法观察海马CA1区LTP效应和免疫组织化学方法观察大鼠海马CA1区CaN蛋白表达水平。结果:与CG大鼠相比,FG大鼠避暗潜伏期缩短,错误次数增加,且差异显著(P<0.01);最大场兴奋性突出后电位(fEPSP)的平均幅值FG大鼠(113.81%±2.36%)较CG大鼠(129.31%±2.38%)显著降低(P<0.01);FG大鼠CaN蛋白表达也较对照组显著上调(P<0.01)。结论:运动疲劳可降低大鼠学习记忆能力,抑制海马CA1区LTP效应,上调CaN蛋白表达。提示:运动疲劳降低大鼠学习记忆功能的生理机制可能与海马CA1区LTP抑制及CaN蛋白表达增多有关。

Objective： To observe the effects of exercise induced fatigue on learning and memory function,long-term potentiation and calcineurin protein expression of rats in hippocampal CA1 area and discuss the physiological mechanism of exercise-induced fatigue on learning and memory function.Methods： 32 healthy male SD rats at 8 weeks age were randomly divided into two groups（control group and fatigue group）.Seven days of increasing load exercise to build exercise-induced fatigue model.Control group was no intervention.After the end of last running,dark avoidance test was used to detect the changes of learning and memory function.At the end of the experiment,stereotaxic neuronal electrophysiological methods in vivo and immunohistochemistry were used to record LTP and observe the distribution and expression of CaN in hippocampus CA1 area.Results： Compared with CG rats,FG rats showed shorted latency time and increased numbers of error（P0.01）.FG rats average level of fEPSP（113.81 % ± 2.36 %）was lower than CG rats（129.31 %±2.38 %）（P0.01）.It found that the level of CaN was up-expressed in rats of fatigue group（P0.01）.Conclusion： Exercise-induced fatigue reduced the learning and memory abilities significantly,inhibited LTP in hippocampus CA1 and up-expressed the level of CaN.The results indicate that the physiological mechanism of exercise-induced fatigue reducing learning and memory function may be related to the inhibition of LTP and the increased expression of CaN protein in hippocampus.