| Objectives: To investigate the effects of repetitive transcranial magnetic stimulation(rTMS)on the migration of neural stem cells(NSCs)in cerebral infarction side in rats and explored possible mechanism in the process.Methods: 135 male Sprague-Dawley adult rats(8 weeks,210±20g)were randomly distributed into sham-operated group(S),model group(M),rTMS-treated cerebral infarction group(R),rTMS+ AMD3100 treated MCAO group(RA)and model+ AMD3100 treated group(MA).It concludes 7 days and 14 days time points.In 7 days time point,each group had 11 rats and each group had 16 animals in 14 days time point.Right MCAO for 90 mins model was used.rTMS-treated group and rTMS+ AMD3100 treated group received intervention once a day for a 7-day or 14-day period from 1 day after surgery,except sham-operated,model or model+ AMD3100 group.m NSS assessment was carried out in all rats on the first,the 7th and the 14 th day after MCAO.Brd U was intraperitoneally administered to all groups in 7 days time point(n= 6 for each group)three times for 12 h following the last rTMS treatment,and rats were sacrificed within 4 h after the last administration.The rats in 14 days time point would be given Brd U in consequently 7 days from the first day after the surgery.Ipsilateral samples(n=5 for each group whatever the time point)of cerebral ischemia including striatum were dissected for Western blotting.m NSS test was used to examine whether rTMS could improve the neurological function,the grip strength meter would be given to test the muscle strength of the front limbs and Fluorescent double-label immunohistochemistry was used to exam the migration of adult NSCs in ipsilateral SVZ.The expressions of SDF-1? and CXCR4 were evaluated by Western blotting,and the survival of neurons would be determined by Nissl staining.Statistical comparisons of results were performed by repeated measurement ANOVA or one-way ANOVA.Bonferroni test was used to post-hoc test.Results: 1.Animals subjected to MCAO suffered severe function deficits 1 day after surgery and there was no significant difference in m NSS values among ischemic rats(P>0.05).Compared with the M and MA groups,the R and RA group exhibited a significantly better neurological statuses at two time points respectively(P<0.05).At 14 days after MCAO,there was also a significant decrease in neurological scale values in the R group compared with those of the RA group(P<0.05).2.There were no difference of GSM values between the ischemic rats(P>0.05).At two time points,compared with the rats in M and MA group,the grip strength was obviously enhanced in R and M group,respectively(P<0.05).The values in RA group were significant increased than the MA group(P<0.05).There were no difference between the R group and RA group(P>0.05),however,the variant became obvious between them at 14 days after the surgery(P<0.05).3.Quantitative analysis of NSC migration was assessed by counting Brd U/DCX-immunostained cells.The migration of NSCs peaked in the peri-infarct region at 14 days after MCAO.At 7 days after MCAO,the number of Brd U/DCX-immunostained cells was significantly higher in the R group than those in the M groups(P<0.05),fewer Brd U/DCX-immunostained cells were observed in the MA group than in the RA groups(P=0.033).At 14 days,there was also a significant difference between the numbers in the R and M/R and RA groups(P> 0.05).Few Brd U/DCX immunostained cells were detected in the S group.4.We used Western blot to analyze the total protein expression of SDF-1? and CXCR4.After normalization with GAPDH,SDF-1? and CXCR4 expression levels increased gradually at 14 days after MCAO,there were significantly differences in the expression of SDF-1? and CXCR4 between M and S,R and M at two time points.At 7 days after MCAO,compared with MA groups,the SDF-1? expression in the RA group showed a significant increase(P<0.05).At 14 days after MCAO,compared with the M and RA groups,the SDF-1? expression in the MA group showed a significant decrease(P< 0.05).In terms of CXCR4 expression,there was also an obvious difference between the R and RA/M and MA/RA and MA groups at 7 and 14 days after MCAO(P< 0.05).5.Significant difference was found in Nissl-positive neurons between sham-operated group and model group(P<0.001)at the 14 th day after MCAO.The survival neurons in rTMS group significantly increased than that in M(P<0.001)and RA groups(p<0.05).And there were obviously increment in the RA group versus MA group(P<0.001),in the M group versus the MA group(P<0.05).Conclusion: 10 Hz rTMS has positive effect in the recovery of motor dysfunction after focal cerebral ischemic stroke.10 Hz rTMS can promote the migration of adult NSCs in the ipsilateral SVZ and played an important role in the regulation of SDF-1?/CXCR4 axis,which might be associated with the neuroprotection and neuroplasticity mechanism of rTMS. |
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