Abstract:

Abstract:Objective To observe the influence of swimming exercise in learning and memory,the concents of amino acids and nNOS expression in prefrontal cortex (PF) of brain in the aging rats,and to explore the mechanism of swimming exercise to improve learning and memory of the aging rats.Methods Twenty SD aging rats (24 months) were chosen and randomly divided into aging control group(SC) and swimming exercise group(SE),and other ten SD adult rats(5 months) were used as adult control group(control).The rats in control and SC groups kept normal activities and the rats in SE group undertook an 8-week swimming exercise with progressively increasing load.Then an 8-arms radial maze was used to assess the capability of learning and memory of the rats and the contents of glutamic acid (Glu) and gamma aminobutyric acid (GABA) in PF,and the nNOS expression in PF was detected and analyzed by using ABC immunohistochemical technique and semi quantitative method.Results Compared with SC group,the Glu content  in PF of the rats in SE group was significantly increased(P<0.05);the GABA content was also increased,but there was no significant difference (P>0.05);the ratio of Glu/GABA was obviously increased(P<0.05).Compared with SC group,the time of completing 8-arms radial maze  of the rats in SE group was shortened (P<0.05);the reference memory error (RME) and total memory error (TE) were obviously decreased (P<0.05,P<0.01);the working memory error (WME) was decreased,but there was no significant difference(P>0.05).Compared with SC group,the amount and area of nNOS in PF  of the rats in SE group were obviously increased (P<0.05),and the gray degree was enhanced (P<0.05).Conclusion Swimming exercise may enhance the learning and memory  abilities of the aging rats and its mechanism might be that the swimming exercise can increase the content of Glu,effectively adjust the ratio of Glu/GABA and reinforce the expression of nNOS in PF at the same time.

Key words: swimming exercise, learning and memory, prefrontal cortex, amino acid, nitric oxide synthase