Medium-intensity acute exhaustive exercise induces neural cell apoptosis in the rat hippocampus

The present study assessed the influence of medium-intensity （treadmill at a speed of 19.3 m/min until exhaustion） and high-intensity （treadmill at a speed of 26.8 m/min until exhaustion） acute exhaustive exercise on rat hippocampal neural cell apoptosis. TUNEL staining showed significantly increased neural cell apoptosis in the hippocampal CA1 region of rats after medium- and high-intensity acute exhaustive exercise, particulady the medium-intensity acute exhaustive exercise, when compared with the control. Immunohistochemistry showed significantly increased expression of the antiapoptotic protein Bcl-2 and the proapoptotJc proteJn Bax in the hippocampal CA1 region of rats after medium- and high-intensity acute exhaustive exercise. Additionally, the ratio of Bax to Bcl-2 increased in both exercise groups. In particular, the medium-intensity acute exhaustive exercise group had significantly higher Bax and Bcl-2 protein expression and a higher Bax/Bcl-2 ratio. These findings indicate that acute exhaustive exercise of different intensities can induce neural cell apoptosis in the hippocampus, and that medium-intensity acute exhaustive exercise results in greater damage when compared with high-intensity exercise.