Apoptosis and autophagy contribute to gender difference in cardiac ischemia-reperfusion induced injury in rats.

AIMS

Gender difference in cardiac ischemia-reperfusion (IR) induced injury has been reported in animal models. However, a large-scale clinical trial found an increase in cardiovascular incidents in women with hormone replacement therapy. The present study is aimed to explore possible mechanisms of gender difference in cardiac IR induced injury.

MAIN METHODS

Male and female Sprague-Dawley rats were subjected to a 30-min coronary arterial occlusion followed by reperfusion. The infarct size and apoptotic cell number at 24h after reperfusion were significantly lower in female rats than in male rats.

KEY FINDINGS

Male rats expressed higher anti-apoptotic protein Bcl2 levels compared with female rats under physiological conditions. However, levels of Bcl2 were reduced significantly after IR in male rats but not in, female rats. Levels of pro-apoptotic protein, Bax and phospho-p38, showed similar under physiological conditions. In response to IR expression of Bax was markedly reduced in female rats but not in male rats, and expression of phospho-p38 was significantly increased in male rats but not in female rats. In addition, female rats showed marked increase of autophagy marker, ratio of LC3B to LC3A, while male rats significantly decreased the ratio in response to IR.

SIGNIFICANCE

Gender difference in IR injury is due to the different regulation of anti-apoptotic protein, pro-apoptotic protein and autophagy protein levels in male rats and levels in female rats. Our results provide better understanding of sex differences in cardiac IR injury.