Treadmill exercise promotes the expression of TGF-β1 and Smad3 protein, inhibiting cell apoptosis after cerebral ischemia

Abstract

Objective To observe the effect of treadmill exercise on the expression of transforming growth factor-β1 (TGF-β1) and its receptor Smad3 protein as well as on cell apoptosis in the ischemic boundary zone, so as to explore how exercise promotes the recovery of neurological function after cerebral ischemia. Methods Thirty adult male Sprague-Dawley rats were randomly divided into a sham group (n=6), a model group (n=12) and an exercise group (n=12). A modified Longa′s method was used to establish an animal model of cerebral ischemia by occluding the right middle cerebral artery in the rats of the model and exercise groups. Those of the sham group were subjected to the same surgical procedure except that no thread was inserted. After 24h the exercise group began treadmill training, while the other two groups were left on the treadmill without training. Modified neurological severity scores (mNSSs) were used to quantify the rats′ neurological functioning on the 3rd, 7th and 14th day after the surgery. The ischemic boundary zone tissue was then dissected to detect the expression of TGF-β1 and Smad3 protein using western blotting. Cell apoptosis was detected by TUNEL staining. Results The average mNSS scores of the exercise group on the 7th and the 14th day were significantly lower than those of the model group at the same time points. The average expression level of TGF-β1 and Smad3 protein in the exercise group was significantly higher than in the model group. The number of TUNEL-positive cells in the exercise group was significantly lower than in the model group on the 14th day. Conclusions Treadmill exercise can improve the recovery of neurological function after cerebral ischemia. It may be partly due to upregulating the expression of TGF-β1 and Smad3 protein, which inhibit cell apoptosis in the ischemic boundary zone. Key words: Cerebral ischemia; Exercise; Transforming growth factor; Smad3 protein; Apoptosis