Objective To determine the effect of treadmill exercise on expression of matrix metalloproteinase-2 (MMP-2) in rats follow-ing traumatic brain injury (TBI). Methods Fifty-five male adult Sprague-Dawley rats were randomly assigned to sham (n=15), control (n=20) and exercise (n=20) groups, the later two groups subjected to unilateral cortical contusion injury (CCI). All the rats were assessed with foot-fault test 6, 12, 18 and 24 days after CCI. Evans blue perfusion was used to evaluate the integrity of the blood-brain-barrier (BBB) 48 hours after CCI. Protein expression of MMP-2 was determined with Western blotting one week after CCI. Results The score of foot-fault test improved more in the exercise group than in the control group 12, 18 and 24 days after CCI (F>4.793, P<0.05). Evans blue extravasa-tion was less in the exercise group than in the control group (t=-8.091, P<0.001), as well as the expression of MMP-2 (t=-13.12, P<0.001). Conclusion Early treadmill exercise can improve the motor function in rats with TBI, which may associate with inhibition of MMP-2 ex-pression to protect BBB integrity.

Objective To investigate the effect of early rehabilitation on rats' motor performance after moderate or severe experimental traumatic brain injury (TBI).Methods After adult Sprague-Dawley rats had received moderate or severe TBI,they were randomly assigned to either a 24 hour exercise group (group A),a 3-day exercise group (group B),a 7-day exercise group (group C) or a control group.Each group was composed of 8 rats.The exercise group endured forced treadmill training on an electric treadmill for 14 consecutive days initiated 24 hours,3 days or 7 days post TBI.The foot-fault and cylinder tests were performed on the 6th,12th,18th,24th and 28th day post injury.On the 28th day the rats were sacrificed and the brains were removed and frozen.The frozen coronal brain sections were stained with cresyl violet (CV) for quantitative evaluation of cortical lesion volume.Results The rats in groups B and C showed significant decreases in the percentage of left forelimb foot faults compared with the control group at the 18th,24th and28th day after injury.In addition,the rats of group C demonstrated significant decreases in the percentage of left forelimb foot-fault at the 12th day after injury.There was no significant difference between group A and the control group in terms of foot fault scores in any of the subsequent test sessions.In the cylinder test the forelimb use asymmetry scores of neither group A nor group B were significantly different from the control group.Group C showed marked locomotor asymmetry improvement at day 28 post-injury.There was no significantly different loss of hemispheric tissue between those groups.Conclusion After treadmill exercise for 14 consecutive days initiated at 3 or 7 days following moderate or severe TBI,rats' motor function improved.The cortical lesion volume was not associated with recovery of motor function.