| Objective: The effects of D-galactose(D-Galactose)on the ability of learning and memory and the expression of GAP-43 in the hippocampus of rats were studied before and after aging of brain,and the neurobiological mechanism of the intervention of aerobic exercise to postpone the aging of brain in rats was investigated.Methods: 60 normal male SD rats with standard weight(400±20g)were randomly divided into 5 groups after 7 days of natural feeding: pre senescence preconditioning group(SD),senescence group(ND),saline control group(NNa),post aging exercise group(NDS)and post aging natural feeding group(NDN).D-galactose(100mg/kg/d)was injected intraperitoneally for 6 weeks to make aging models in some rats.After aging modeling,each group was randomly divided into 2 groups(SDM?SDN?NDM?NDN?NNa M?NNaN?NDSM?NDSN?NDNM?NDNN),group N received 7 days of natural feeding,and group M received 7 days Morris water maze test intervention.According to the experimental scheme,two batches were selected to evaluate the success of the rat brain aging model with the changes of superoxide dismutase(SOD)/ glutathionge peroxidase(GSH-PX)activity(glutathionge peroxidase,GSH-PX)and the content of malondialdehyde(malonic dialdehyde,MDA).Real-time PCR,Western,and immunofluorescence techniques were used to determine the hippocampus of each group.The expression of AP-43 gene and protein.Results:(1)for 6 weeks of NaCl or D-Galactose intraperitoneal injection,it was observed that the mental state of the ND group was poor,the skin elasticity and hair luster were poor,and the hair dehairs appeared,and the diet was reduced at the same time;the mental state of the NDN group was worse than that of the ND group,the skin hair elasticity was poor and the loss of hair was serious and the diet decreased.The reason may be due to the model after the model.After 4 weeks of natural feeding,the aging time was prolonged,and the mental state,glossiness and diet of the SD group were better than that of the ND group,and the NDS group was better than the other four groups,and the diet was more.(2)The results of free radical detection: there was no significant difference in the content of MDA and the activity of SOD and GSH-PX in group M and N group(P>0.05).The MDA content in cerebral cortex of rats in NNa group was significantly lower than that in group ND(P<0.05),SOD and GSH-PX activity was significantly higher than that of the group.It was significantly higher than that in group NDS(P<0.01),but the activities of SOD and GSH-PX were significantly higher than those in NDS group(P<0.01).(3)The results of the navigation experiment showed that in the course of the 6 day positioning navigation experiment,the average escape latency of each group was different with the increase of training time.Compared with the average escape latency of first days,the average escape latency of all groups second days was significantly lower than first days(P<0.01).Compared with the average escape latency of second days,all groups were compared with the average escape latency.The average evasion latency of third days was significantly lower than first days(P<0.01).The average escape latency of rats in group NNaM and group NDSM began to stabilize(P>0.05)at the beginning of third,while the average escape latency of fourth days was stable(P>0.05)in group SDM,NDM and NDNM,indicating that the model of aging rats was successful,and the average escape time of the first day escape period of the group NDNM rats was significant.Rats were higher than group NNaM(P<0.01).(4)Immunofluorescence staining results showed that the immunological products of hippocampus GAP-43 were brown,and the positive expression was mainly located in neuronal cell bodies,axons and growth cones.The results of Real-time PCR and Western blot showed that the expression of GAP-43 gene and protein expression in hippocampus: compared with the NNa group,the expression of GAP-43 gene and protein in the hippocampus of ND group decreased significantly(P<0.01),and there was no significant difference between the SD group and the protein in the SD group compared with the ND group.Compared with the ND group,the expression of GAP-43 gene and protein in the hippocampus of NDN group decreased significantly(P<0.01),and the expression of GAP-43 gene and protein in the hippocampus of NDN group decreased significantly(P<0.01)compared with the group of NDS group(P<0.01).Conclusion:(1)By injecting D-galactose to rats for up to 6 weeks,the content of MDA in the cerebral cortex of rats increased significantly,the activity of SOD and GSH-PX decreased significantly and the spatial learning and memory ability decreased,which was consistent with the clinical symptoms of aging.It showed that the model of brain senescence induced by D-galactose injection of 6 weeks was successful.(2)Aerobic exercise intervention on rats before aging did not have a positive effect on brain senescence,learning and memory ability and the expression of GAP-43 gene and protein in the hippocampus.(3)Aerobic exercise intervention in rats after aging can delay the aging process of the brain,improve the learning and memory ability,and increase the expression of GAP-43 gene and protein in the hippocampus.(4)The up-regulated expression of GAP-43 gene and protein in the hippocampus of rats may be one of the biological mechanisms of aerobic exercise intervention to delay the aging of brain and the decline of spatial learning and memory ability in rats. |
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