Decreased metabolism and increased serum concentrations of LH and FSH following nephrectomy of the rat: absence of short-loop regulatory mechanisms.

Abstract

Bilateral nephrectomy of castrated adult rats of either sex resulted in a decreased rate of LH and FSH clearance. The half-life (50% decrease following hypophysectomy) of serum LH increased nearly 8-fold (from approximately 30 min to approximately 4 hr) while the half-life of FSH increased approximately 3-fold (from approximately 2 hr t approximately 6 hr). These alterations in hormone clearance were accompanied by quantitatively similar increases in the serum concentrations of LH and FSH, suggesting that the rates of hormone secretion were not affected by nephrectomy.The increases in serum gonadotropins were observed as early as 4 hours, and persisted for at least 24 hr after removal of the kidneys. In intact male rats and in orchidectomized testosteronetreated animals nephrectomy produced a 3-fold increase in serum FSH but did not produce an increase i serum LH or testosterone concentrations.These data indicate that the kidney may play an important role in the clearance of LH and FSH in the rat and suggest that, with the possible exception of LH in the intact male, LH and FSH release are not inhibited by increased serum concentrations of endogenous LH or FSH. The data appear to contradict the suggestion that gonadotropin secretion is controlled by a “shot-loop” inhibitory feedback o gonadotropins on hypothalamohypophyseal function. (Endocrinology95: 1582,1974)