The Effect Of Early Treadmill Exercise On Motor And Cognitive Function Deficit Following Severe TBI In Rats

Background:Traumatic brain inury(TBI) is a world wide public health problem. With the improvement of the critical care in recent years, the TBI patient mortality declined obviously. Survivors of TBI often have long term cognitive impairments. Even some medicines have been developed to treat TBI, but there are few sure effective drugs in clinical. Rehabilitation intervention also is the major measure which is good to TBI. Recent some clinical researches indicate that early physical rehabilitation after severe TBI may improve the long-term function. However, there is poor agreement on intervention time and exercise intensity in severe TBI patients.Methods:To invest the effect of rehabilitation initial at different times on rats’neuromotor and cognitive function performance after TBI. Adult SD rats had received a severe controlled cortical impact (CCI). Animals in the exercise group were induced by forced high intensity treadmill training on an electric treadmill for 14 consecutive days initiated at 24 hour、3-day and 7-day post TBI. After TBI, the behavioral tests were performed post injury. On 26 days post injury, animals were anaesthetized and evaluated for quantitative cortical lesion volume. The levels of BDNF and synapsin protein samples of cortical were determined by Western blot. To determine the effect of early low intensity exercise on brain damage, motor function, cognitive function and molecules level in cortex and hippocampus following TBI. Animals in the exercise group were induced by forced treadmill training at a low intensity on an electric treadmill for 14 consecutive days initiated at 24 hour post TBI. On 21 days post injury, rats were tested for spatial learning and memory in a Morris Water Maze(MWM).Results:The results showed that both 3-day and 7-day exercise group demonstrated improved coordination performance compared to non-exercise rats after high intensity exercise (p<0.05). The 3-day and 7-day exercise group showed locomotor asymmetry improvement, but did not meet statistically significant. The 24 hour exercise group didn’t demonstrate recovery of motor function after compared to non-exercise rats at all subsequent test sessions after high intensity exercise. Treadmill exercise can’t take effect on Morris water maze performance after severe traumatic brain injury. We also founded that Brain-derived neurotrophic factor (BDNF) protein in the contralateral cortex was increased in the exercise group. We also didn’t observe significant change of lesion volume in exercise group rats. The results also demonstrated that animals in low intensity exercise group showed a significant decrease in the percentage of left forelimb foot faults compared with values from control animals. The low intensity exercise group rats showed marked locomotor asymmetry improvement at day 21 and 24 post injury. There was no statistically significant loss of hemispheric tissue between two groups. The results revealed that the rats in the low intensity exercise group had a shorter latency to locate a platform and a significantly better improvement in spatial memory in the Morris water maze (MWM) compared to the control group (p< 0.05). We also founded that Brain-derived neurotrophic factor (BDNF) protein in the contralateral cortex and hippocampus was increased in the low intensity exercise group.Conclusions:In summary, rats treated with high intensity treadmill exercise for 14 consecutive days initiated at day 3 or day 7 following severe TBI improve function of motor. Rats treated with low intensity treadmill exercise for 14 consecutive days initiated at 24 hour following severe TBI improve function of motor and cognitive function. The cortical lesion volume isn’t associated with recovered motor function. Mechanisms underlying recovery of motor or cognitive function after treadmill exercise may be related to the up-regulation of cortex or hippocampus BDNF.