Endotoxin-induced changes in sex steroid hormone levels in male rats.

Intravenous administration of Escherichia coli endotoxin (ENDO) was found to induce profound time and dose dependent changes in the serum steroid hormones, oestrone (E1), oestradiol (E2), corticosterone (B), progesterone (P4), 17 alpha-OH progesterone (17 alpha OHP4), and testosterone (T) of intact male rats. These changes were rapid, with a maximal response at 2 h and a return to close to normal values by 4 h. Non-lethal doses (0.01-2 mg/kg) of ENDO induced large increases in oestrogens (3-9-fold), P4 (4-fold) and B (2-3-fold) and decreased serum T (2-fold). The greatest increase in E2 level was seen with an ENDO dose of 2 mg/kg. Serum E1, E2 and T did not change in response to lethal ENDO doses (4-8 mg/kg); B, P4 and 17 alpha OHP4 levels alone were moderately elevated. Systemic mean arterial pressure was unchanged, except at the highest ENDO dose used. Thus, the hormonal responses are unlikely to be the result of hemodynamic changes. Low doses of ENDO did not produce an increase in serum E1 and E2 in adrenalectomized or orchidectomized rats. These results indicate that oestrogens are largely produced in the testis. The aromatization of the testicular and adrenal androgens can be stimulated by glucocorticoid.