Assessment of anti-estrogenic activity of tamoxifen in transgenic mice expressing an enhanced green fluorescent protein gene regulated by estrogen response element

Paternal fenvalerate exposure influences reproductive functions in the offspring

Fenvalerate (Fen), a synthetic pyrethroid insecticide, has been shown to have adverse effects on male reproductive system. Thus, the aim of the present study was to elucidate whether these adverse effects are passed from exposed male mice to their offspring. Adult male mice received Fen (10 mg/kg) daily for 30 days and mated with untreated females to produce offspring. Fenvalerate significantly changed the methylation status of angiotensin I-converting enzyme (Ace), forkhead box O3 (Foxo3a), huntingtin-associated protein 1 (Hap1), nuclear receptor subfamily 3 (Nr3c2), promyelocytic leukemia (Pml), and Prostaglandin F2 receptor negative regulator (Ptgfrn) genes in paternal mice sperm genomic DNA. Further, Fen significantly increased sperm abnormalities; serum testosterone and estradiol-17ß level in adult male (F0) and their male offspring (F1). Further, paternal Fen treatment significantly increased the length of estrous cycle, serum estradiol-17ß concentration in estrus, and progesterone levels in diestrus in female offspring (F1). These findings suggest that adverse effects of paternal Fen exposure on reproductive functions can be seen not only in treated males (F0) but also in their offsprings.

Estrogen, efferent ductules, and the epididymis

Estrogen's presence in the male reproductive system has been known for over 60 years, but its potential function in the epididymis remains an important area of investigation. Estrogen is synthesized by germ cells, producing a relatively high concentration in rete testis fluid. There are two estrogen receptors (ESR), the presence of which in the head of the epididymis is well documented and consistent between species; however, in other regions of the epididymis, their expression appears to be isotype, species, and cell specific. ESR1 is expressed constitutively in the epididymis; however, its presence is downregulated by high doses of estrogen, making the design of experiments complicated, as the phenotype of the Cyp19a1(-/-) mouse does not resemble that of the Esr1(-/-) mouse. Ligand-independent and DNA-binding Esr1 mutant models further demonstrate the complexity and importance of both signaling pathways in maintenance of efferent ductules and epididymis. Data now reveal the presence of not only classical nuclear receptors, but also cytoplasmic ESR and rapid responding membrane receptors; however, their importance in the epididymis remains undetermined. ESR1 regulates ion transport and water reabsorption in the efferent ducts and epididymis, and its regulation of other associated genes is continually being uncovered. In the male, some genes, such as Aqp9 and Slc9a3, contain both androgen and estrogen response elements and are dually regulated by these hormones. While estrogen pathways are a necessity for fertility in the male, future studies are needed to understand the interplay between androgens and estrogens in epididymal tissues, particularly in cell types that contain both receptors and their cofactors.

Reduced endogenous estrogen delays epididymal development but has no effect on efferent duct morphology in boars

The study presented herein was designed to test the hypothesis that reduced endogenous estrogen in the boar alters efferent duct morphology, epididymal morphology, and steroid receptor expression. Twenty-eight littermate pairs of boars were treated with Letrozole, an aromatase inhibitor, or with vehicle from 1 week of age until castration at 2 through 8 months. Efferent ducts and epididymides were examined for morphological development and steroid receptor expression. Efferent duct morphology was not different between control and Letrozole-treated animals at any examined age. Androgen receptor (AR), estrogen receptor α (ERα), and β (ERβ) were expressed in the epithelial cells of the efferent ducts at all ages; expression was similar in control and treated animals. Morphological development of the caput and corpus was delayed in Letrozole-treated animals, but this delay was transient since morphology was similar between control and treated animals at 8 months. The cauda did not show a delay in development, but was more developed in treated animals at 2 months. AR, ERα, and ERβ were expressed in all three epididymal regions; no difference was observed between control and treated animals. In summary, estrogen appears to be important for development of the epididymis; however, the cauda may be regulated differently than the caput and corpus. Results for the efferent ducts suggest that the normally high endogenous estrogens are not required for regulation of fluid reabsorption in the boar. It also suggests that any ER activation required for maintenance of efferent duct morphology and function is normal in Letrozole-treated boars.