Adrenal glucocorticoids do not mediate impaired reproductive function induced by lipopolysaccharide in rats

It has been reported that the impaired reproductive function found in endotoxemia is mediated by proinflammatory cytokines, prostaglandins, and opioid peptides in the brain and that the synthesis of all these molecules is stimulated by endotoxins. The role of glucocorticoids in the endotoxin-induced hypogonadism may also be important, because endotoxins are potent stimulators of the hypothalamo-pituitary-adrenal axis, and glucocorticoids are inhibitory to the reproductive system. However, no previous study examined directly whether glucocorticoids contribute to the endotoxin-induced suppression of the reproductive competence until a very recent study performed in sheep. To examine directly such a role of glucocorticoids in rats, we compared the effects of lipopolysaccharide (LPS) on the pulsatile luteinizing hormone (LH) release between adrenal-intact orchidectomized rats and adrenalectomized plus orchidectomized rats. The latter group received a constant subcutaneous infusion of corticosterone to maintain physiological plasma levels of the steroid. An intravenous injection of LPS promptly decreased both amplitude and frequency of the LH pulses in the orchidectomized rats, and the LPS effects were very similar in the double endocrinectomy group which did not show an increased corticosterone release after LPS. These results strongly suggest that glucocorticoids do not have a significant role in mediating the LPS-induced acute suppression of pulsatile LH secretion in orchidectomized rats.