Reducing estrogen synthesis does not affect gonadotropin secretion in the developing boar

E. E. At-Taras, Alan J Conley, T. Berger, Janet F. Roser

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Boars have high concentrations of plasma and testicular estrogens, but how this hormone is involved in feedback regulation of the gonadotropins and local regulation of testicular hormone production is unclear. The present study examined the effects of reducing endogenous estrogens by aromatase inhibition on concentrations of plasma LH and FSH and on testicular and plasma concentrations of testosterone (T) and immunoreactive inhibin (INH). Thirty-six littermate pairs of boars were used. One boar from each pair was assigned to the control group (vehicle); the other boar to the treatment group (aromatase enzyme inhibitor, Letrozole, 0.1 mg/kg body weight [BW]). Weekly oral treatment started at 1 wk of age and continued until castration at 2, 3, 4, 5, 6, 7, or 8 mo. Plasma concentrations of gonadotropins, INH, T, estradiol (E2), and estrogen conjugates (ECs) were determined. Testicular tissue was collected at castration for determination of INH and T and for confirmation of reduced aromatase activity. The acute effects of aromatase inhibition on gonadotropins were monitored in two adult boars treated once with Letrozole (0.1 mg/kg BW). Treatment with the aromatase inhibitor reduced testicular aromatase activity by 90% and decreased E2 and ECs without changing acute, long-term, or postcastration LH and FSH. Plasma T, testicular T, and circulating INH concentrations did not change. Testicular INH was elevated in treated boars compared with controls. In conclusion, estrogen does not appear to play a regulatory role on gonadotropin secretion in the developing boar. This is in direct contrast to findings in males of several other species.

Original languageEnglish (US)
Pages (from-to)58-66
Number of pages9
JournalBiology of Reproduction
Volume74
Issue number1
DOIs
StatePublished - Jan 2006

Fingerprint

Inhibins
Gonadotropins
Aromatase
letrozole
Estrogens
Testicular Hormones
Aromatase Inhibitors
Castration
Body Weight
Enzyme Inhibitors
Testosterone
Estradiol
Control Groups

Keywords

  • Estradiol
  • Follicle-stimulating hormone
  • Inhibin
  • Luteinizing hormone
  • Testosterone

ASJC Scopus subject areas

  • Cell Biology
  • Developmental Biology
  • Embryology

Cite this

Reducing estrogen synthesis does not affect gonadotropin secretion in the developing boar. / At-Taras, E. E.; Conley, Alan J; Berger, T.; Roser, Janet F.

In: Biology of Reproduction, Vol. 74, No. 1, 01.2006, p. 58-66.

Research output: Contribution to journalArticle

At-Taras, E. E. ; Conley, Alan J ; Berger, T. ; Roser, Janet F. / Reducing estrogen synthesis does not affect gonadotropin secretion in the developing boar. In: Biology of Reproduction. 2006 ; Vol. 74, No. 1. pp. 58-66.
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