ABSTRACT
Objective:To observe the effect of early exercise intervention on the corticospinal tract of rats with cerebral infarction.Methods:Eighteen male Sprague-Dawley rats were randomly divided into a sedentary group (SED), a 1 day later exercise group (1D) and a 1 week later exercise group (1W), each of 6. A modified Longa′s method was used to occlude the middle cerebral artery to model a stroke. Rats in the 1D and 1W groups started exercising 1 day and 1 week after the modeling, while those in the sedentary group were placed on a stationary treadmill for 30 minutes every day. Modified neurological severity scores (mNSSs) were used to quantify neurological functioning after 1, 4 and 8 weeks. Magnetic resonance imaging was used to calculate the infarct volume ratio, and diffusion tensor imaging was used to detect the fractional anisotropy ratio (rFA) of the corticospinal tract for correlation with the mNSS scores. The corticospinal cord′s morphology was observed using DTT.Results:After 1 week the average mNSS score of the 1D group was significantly lower than the other two groups′ averages. At 4 weeks the average mNSS scores of both the 1D and the 1W group were significantly lower than the sedentary group′s average. At 8 weeks the 1D group′s average mNSS score was significantly lower than those of the other two groups, while that of the 1W group was significantly lower than the sedentary group′s average. At 1 and 4 weeks after modeling the average infarct volume ratio in the 1D group was significantly lower than those of the other groups. By 4 weeks the average infarct volume ratio of the 1W group was significantly lower than that of the sedentary group, and by 8 weeks the average infarct volume ratios of both the 1D and 1W groups was significantly lower than that of the sedentary group. After 1 week the average rFA of the 1D group was significantly lower than that of the sedentary group, but by 4 weeks the averages of the 1D group and the 1W group were both significantly higher than the sedentary group′s average. At 8 weeks the 1D group′s average rFA was significantly above that of the 1W group and of the sedentary group, and that of the 1W group was significantly higher than that of the sedentary group. After 8 weeks the corticospinal tracts in the 1D group appeared to be more symmetrical than those of the other 2 groups. The rFA results correlated strongly with the mNSS scores ( r=-0.707). Conclusions:Exercise can promote corticospinal cord remodeling and improve neurological function after cerebral infarction, at least in rats. It should be started as early as possible.