Estrogen attenuates HSP 72 expression in acutely exercised male rodents

Estrogen has been shown to reduce post-exercise skeletal muscle damage. Exe rcise-induced muscle damage maybe a factor in the elevated post-exercise ex pression of heat-shock proteins (HSPs). Thus, the present investigation was conducted in order to examine the influence of estrogen on post-exercise l evels of HSP 72 and heat-shock cognate, HSC 73, in male and female rodents. Prior to an acute bout of treadmill. running, male and female Sprague-Dawl ey rats received daily injections of either 40 mu g.kg(-1) of beta-estradio l 3-benzoate or olive oil vehicle for 2 weeks. A two- to fourfold reduction in post-exercise HSP 72 content was observed in the heart, liver, lung and red and white vastus muscles of estradiol-treated males compared with thei r vehicle-injected counterparts (P < 0.05). Compared to the males, the fema les had significantly lower post-exercise HSP 72 levels which were not affe cted by estradiol supplementation. Moreover, estradiol administration in ma le rodents resulted in a HSP response similar to that of females following exercise. Thus, the results of the present investigation suggest that estro gen is the factor responsible for the observed differences in post-exercise HSP 72 levels between males and females.