Inhibitory and stimulatory regulation of testicular inhibin B secretion by luteinizing hormone and follicle-stimulating hormone, respectively, in the @entity2608 ( XXXX ).

@entity1 @entity251 @entity72437 @entity23653 @entity25086 @entity1176 @entity6126 @entity2608
This study examined the relative role of FSH and LH in governing testicular inhibin B secretion in the @entity2608 . Adult male monkeys, rendered hypogonadotropic and hypogonadal by administration of a @entity1176 receptor antagonist ( @entity23653 ), were implanted with @entity251 (T)-filled or empty capsules. Following T-induced restoration of spermatogenesis, both groups received recombinant @entity1 FSH and vehicle for 12 d. Juvenile male monkeys received an 11-d infusion of single-chain recombinant @entity1 LH and recombinant @entity1 FSH, either alone or in combination. In adults, chronic @entity6126 resulted in a modest reduction of circulating @entity25086 levels, which was more than fully reversed by FSH. In the presence of T, which exerted a marked suppression in inhibin B secretion, FSH restored inhibin B levels only to those observed before @entity23653 treatment. In juveniles, treatment with single-chain recombinant @entity1 LH led to a suppression of inhibin B secretion and curtailed the FSH-induced stimulation of this testicular hormone. The T-induced decrease in inhibin B secretion was associated with suppression in @entity72437 mRNA levels, but FSH stimulation of inhibin B secretion occurred in the absence of clear changes in expression of this subunit gene. These findings indicate that inhibin B secretion by the monkey testis is governed by the inhibitory and stimulatory action of LH and FSH, respectively. The action of LH is presumably indirect and likely mediated by T inhibition of @entity72437 gene expression. The molecular basis of the stimulatory action of FSH on inhibin B secretion requires further study.
