Inhibitory and stimulatory regulation of testicular inhibin B secretion by luteinizing hormone and follicle-stimulating hormone, respectively, in the rhesus monkey (Macaca mulatta).
This study examined the relative role of FSH and LH in governing testicular inhibin B secretion in the rhesus monkey. Adult male monkeys, rendered hypogonadotropic and hypogonadal by administration of a GnRH receptor antagonist (acyline), were implanted with testosterone (T)-filled or empty capsules. Following T-induced restoration of spermatogenesis, both groups received recombinant human FSH and vehicle for 12 d. Juvenile male monkeys received an 11-d infusion of single-chain recombinant human LH and recombinant human FSH, either alone or in combination. In adults, chronic hypogonadotropism resulted in a modest reduction of circulating inhibin B 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 acyline treatment. In juveniles, treatment with single-chain recombinant human 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 inhibin-beta(B) 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 inhibin-beta(B) gene expression. The molecular basis of the stimulatory action of FSH on inhibin B secretion requires further study.
Ramaswamy
Suresh
S
Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Marshall
Gary R
GR
Pohl
Clifford R
CR
Friedman
Robert L
RL
Plant
Tony M
TM
D000367:Age Factors; D000818:Animals; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D012739:Gonadal Steroid Hormones / Q000494:pharmacology; D007006:Hypogonadism / Q000188:drug therapy / Q000378:metabolism; D007265:Inhibins / Q000235:genetics / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008253:Macaca mulatta; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D009919:Orchiectomy; D013737:Testis / Q000187:drug effects / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology
D012739:Gonadal Steroid Hormones; D009842:Oligopeptides; C422364:inhibin B; D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C109238:acyline