Suppression of endogenous estrogen during development affects porcine epididymal sperm maturation

Megan J. McCarthy, Eeman E. At-Taras, Christopher A. Pearl, Barbara S. Nitta-Oda, Janet F. Roser, Alan J Conley, Trish Berger

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Estrogen plays an important role in male reproduction, critical for sustained fertility in some species. Reducing estrogen's interaction with its receptor(s) in monkey and mouse models is associated with reduced sperm motility and, in some cases, documented elimination of sperm fertilizing ability, suggesting that normal epididymal function may be estrogen dependent. The objective of these experiments was to evaluate the effects of reduced endogenous estrogen on development of epididymal function in the pig, a species in which males have very high levels of endogenous estrogen. Letrozole, a potent inhibitor of estrogen synthesis, was administered to neonatal boars from 1 week of age and markedly suppressed estrogen production. Epididymal function assessed as acquisition of sperm fertilizing ability (in vitro fertilization of zona-free oocytes) was reduced in Letrozole-treated animals at 24 and 28 weeks of age (23% and 30% fertilization, respectively compared with 37% and 54% in vehicle controls) but had recovered by 32 weeks of age. Cauda epididymal sperm numbers were reduced in treated animals (35% of control values at 20 weeks of age) but appeared to be recovering at 32 weeks of age. Reduction of endogenous estrogen had no effect on other aspects of epididymal function (percentage of motile sperm, sperm motion parameters, sperm head morphometrics, or ability of sperm to undergo an acrosome reaction). Reducing endogenous estrogen during postnatal development appears to have transient effects on porcine epididymal function. These transient effects suggest that the pig, with its high endogenous estrogen, may respond differently than other species to reduced estrogen synthesis.

Original languageEnglish (US)
Pages (from-to)1122-1128
Number of pages7
JournalMolecular Reproduction and Development
Issue number9
StatePublished - Sep 2006


  • Acrosome-reaction
  • Aromatase
  • Boar
  • Estrogen inhibition
  • Fertilization

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology


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