The Mechanism Of Physical Exercise Influences Behavioral Ability Of Developmental Seizure-induced Cognitive Deficit Of Rats

Object:To explore the long-term effects of penicillin-induced development seizures and physical exercise on learning and memory.Methods:56 male Sprague-Dawley rats(posmatal days[PD]21) were randomly divided into four groups:the control group(CONT1),the control plus exercise group(CONT2),the seizure group(EXP1) and the seizure plus exercise(EXP2).10 rats were for each of the two control groups assigned, and the surplus 36 rats were kindled by penicillin(4.5×10⁶U·kg^-1·d^-1,ip) once every other day for consecutive 6 times.Control rats were injected equal amount of normal sodium(NS) for the same time.The 20 qualified models of convulsant rats were randomly divided into the two EXP groups.On PD39～PD44 and PD61～PD65,subjects of the four groups were tested on the Morris water maze,and from PD49 to PD54,the rats of CONT2 and EXP2 were give access to running wheels,twice a day for consecutive 6 days.All rats of the four groups were sacrificed after the second Morris water test,for getting the sample of brain,and rats in each group were all used to receive immunohistochemical staining for GluR-2.and Timm staining. Results:In the first Morris water maze test,there were significant difference of latency between the four groups(F=5.21,P=0.027<0.05),and the latency of the two EXP groups were significantly longer than the two CONT groups(P<0.05);In the probe trial,the two EXP groups' number of passes through target area were significantly less than the two CONT groups; And in the second water maze test,there were significant effects of exercise on the latency of EXP2 comparing to the EXP1 group(F=11.86,P=0.0023< 0.01);And two EXP groups' number of passes through target area were still significantly less,than the two CONT groups after exercise training(P<0.05), and there were no significant difference between EXP1 and EXP2;And there were no effects of seizure on swimming speed between the four groups(P> 0.05);The MFS increased in the hilus of dentate gyrus and CA3 region in the two seizure groups,and there were significant difference between four groups(P<0.05);In the immunohistochemical staining of GluR-2,the gray value of two seizure groups were significantly lower than two control groups(P<0.05).Conclusion:Morris maze performance of learning and spatial memory was significantly impaired among recurrent penicillin-induced-seizure subjects, which might be associated with the down-regulated of GluR-2 expression and mossy fiber sprouting in hippocampus;Exercise significantly improved performance of leaming but not spatial memory,which might be associated with up-regulated expression of GluR-2 and decreasing of mossy fiber sprouting in hippocampus.