International Journal of Preventive Medicine (Int J Prev Med)2008-7802022015020314721472EN20150203<strong>Background:</strong> Renal ischemia-reperfusion (RIR) is the main cause of renal failure. The incidence of RIR injury seems to be gender-related due to female sex hormone; estrogen. This study was designed to investigate the protective role of estrogen against RIR injury in male and <br />ovariectomized female rats.<br /><strong>Methods:</strong> Thirty-nine Wistar rats were used in this study as male and ovariectomized female rats in the sham-operated, RIR, and estradiol-treated plus RIR groups. The RIR was induced by clamping the renal vessels for 45 min and then 24 h of reperfusion. All animals fnally were sacrifced for the measurements.<br /><strong>Results:</strong> The serum levels of creatinine and blood urea nitrogen and kidney tissue damage score signifcantly increased in both male and female RIR rats (P &lt; 0.05). Estradiol however signifcantly attenuated theses parameters (P &lt; 0.05) toward normal levels in female (P &lt; 0.05), but not in male rats. Kidney weight increased in both genders and estradiol intensifed it in the male rats (P &lt; 0.05). Uterus weight was increased by estradiol in female rats (P &lt; 0.05) and testis weight did not alter in male rats.<br /><strong>Conclusions:</strong> Estradiol demonstrated a protective role against RIR injury in female rats; however, estradiol as an antioxidant could not protect the male kidney from RIR injury.<br /><strong>Keywords:</strong> Estrogen, gender, rat, renal ischemia-reperfusionhttp://ijpm.mui.ac.ir/index.php/ijpm/article/view/1472http://ijpm.mui.ac.ir/index.php/ijpm/article/download/1472/1771