关键词: 游泳, 运动, 学习, 记忆能力, 小脑, 食欲素A, 实验

Abstract: BACKGROUND: Exercise can improve people's cognitive ability, but the specific mechanism is not clear in the cerebellum. Studies have been reported that Orexin A is related to learning and memory.  
OBJECTIVE: To explore the effects of two different kinds of swimming exercise interventions on the spatial learning and memory ability and the expression of Orexin A in the rat cerebellum so as to explore the potential mechanism of exercise intervention effect on learning and memory abilities. 
METHODS: Thirty-six male Sprague-Dawley rats were randomly divided into three groups, including normal group (n=10), moderate load exercise group (n=13) and overload exercise group (n=13). We built the animal model by swimming. The rats in the normal group were fed normally for 8 weeks. The rats in moderate load exercise group were performed by the moderate load exercise intervention for 8 weeks, while those of the overload exercise group were subjected to overload exercise intervention for 8 weeks. The weights of three groups of rats were weighed every day. The 8-day Morris water maze test was performed to test the escape latency and the number of crossing the platform in the three groups of rats. Rat’s cerebellum and blood were collected 24 hours later. The serum testosterone level, Orexin A mRNA expression in the cerebellum and immunofluorescence expression of Orexin A in the cerebellum were detected.
RESULTS AND CONCLUSION: On the 1st day, the moderate load exercise group took the shortest time to navigate the platform among the three groups of rats. The average escape latency of moderate load exercise group was significantly lower than that in the normal group (P < 0.01), while there was no significant difference in the average escape latency between overload exercise group and normal group (P > 0.05). Spatial exploration experiment was designed for 1 day, and the average number of crossing the platform in the moderate load exercise group was significantly higher than that in the normal group (P < 0.05), while the average number of crossing the platform in the overload exercise group was significantly lower than that in the normal group and moderate load group (P < 0.05, P < 0.01). The results of real-time quantitative PCR indicated that the expression of Orexin A mRNA in moderate load exercise group was significantly higher than that in the normal group (P < 0.01). Compared with the normal group, the expression of Orexin A mRNA in the overload exercise group was significantly lower (P < 0.05). Immunofluorescence assay revealed that Orexin A protein was mostly distributed in the cytoplasm of cerebellar nerve cells, surrounding the nucleus. Compared with the normal group, the mean absorbance value of Orexin A in the moderate load exercise group was significantly increased (P < 0.05), while the mean absorbance value of Orexin A in the overload exercise group was not significantly lower (P > 0.05). Therefore, long-term moderate load exercise training can improve the spatial learning and memory ability of rats, and the molecular mechanism may be the high expression of Orexin A in the cerebellum. Based on the intensity of moderate-load exercise training, with the increase of exercise load, long-term overload exercise training can decrease the expression of Orexin A mRNA in the cerebellum and the spatial memory ability of rats.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: swimming, exercise, learning, memory ability, cerebellum, Orexin A, experiment