Expression of lactoferrin in the boar epididymis: effects of reduced estrogen.

Lactoferrin is regulated by estrogen in the female reproductive tract and evidence in immature mice suggests that it may be estrogen regulated in males as well. The estrogen regulation of lactoferrin in the epididymis of the boar, a high estrogen-producing male, is unknown. This study was designed to test the hypothesis that lactoferrin expression in the boar epididymis is regulated by estrogen. Twenty-one littermate pairs of boars were treated with vehicle or Letrozole, an aromatase inhibitor, from 1 week of age until castration at 2 through 8 months. Epididymal tissue was collected at castration and fixed for immunolocalization of lactoferrin. Epididymal and testicular tissues were also collected from five mature boars (1-2.5 years) and fixed for immunocytochemistry (ICC). Lactoferrin was localized in the principal cell cytoplasm of the caput, corpus and cauda of developing boars but only in the corpus and cauda of mature boars. Basal cells were negative for lactoferrin. Sperm in the corpus and cauda was also positive for lactoferrin. The efferent ducts and testes were negative for lactoferrin. Intensity of lactoferrin immunostaining increased with age in the corpus and cauda regardless of treatment. Reduced endogenous estrogen in the epididymis during development did not affect the intensity of immunostaining between control and Letrozole-treated animals. Lactoferrin expression in the epididymis of the developing boar does not appear to be regulated by estrogen.