Effect of estradiol on endotoxin-induced changes in steroid hormone levels and lethality in male rats.

We examined the effect of exogenous estradiol on the changes in serum steroid hormone levels induced by a nonlethal dose of Escherichia coli endotoxin in male rats and the deaths due to nonlethal and lethal doses of endotoxin. Injection of estradiol 5 min before a nonlethal dose of endotoxin changed the serum sex steroid hormone response of male rats to endotoxin. The serum estrogen concentrations of estradiol + endotoxin-treated rats decreased by 50% (P < 0.001), while those of the endotoxin-treated rats increased (2- to 5-fold). The serum androgen concentrations of estradiol + endotoxin-treated rats did not change significantly, while those of endotoxin-treated rats dropped to 30-40%, P < 0.001. Exogenous estradiol also appeared to influence the percentage of endotoxin-induced deaths in a dose-dependent manner. It reduced the number of deaths induced by nonlethal (2 mg/kg) dose of endotoxin but increased the number of deaths induced by a highly lethal dose (8 mg/kg). These results, together with the known relationships between estrogen and the immune response, suggest that estrogens affect the course of septic shock in a complex fashion and may have either protective or deleterious effect.