Background: Although acute thermal stress appears to be one of the most effective stressors that increase the intra- and extracellular concentrations of heat shock protein 72 (Hsp72), 17β-estradiol has been shown to inhibit heat-induced Hsp72 expression. Materials and Methods: To determine whether severe whole-body hyperthermia (increase in rectal temperature up to 39.5 °C) induced by lower-body heating is a sufficient stimulus to modulate hormonal (17β-estradiol, progesterone, prolactin, epinephrine, and norepinephrine) and extracellular Hsp72 responses, we investigated young adult women (21 ± 1 yr). Results and Conclusions: In the present study, we show that a severe whole-body hyperthermia (increase in rectal temperature of approximately 2.6 °C and heart rate of approximately 80 bpm from baseline) was sufficient to increase 17β-estradiol, progesterone, and prolactin and catecholamine norepinephrine concentration. Moreover, we show that the concentration of extracellular Hsp72 and catecholamine epinephrine were not affected by severe whole-body hyperthermia in young adult women. From the functional point of view, expression of ovarian hormones induced by passive heat stress may have therapeutic potential for young adult women in, for example, estrogen treatment and overall women's health.
Keywords: Hyperthermia; catecholamines; estradiol; passive heating; prolactin.