Organizational effects of the antiandrogen, vinclozolin, on penis development in the mouse†

Abstract

Endocrine disrupting chemicals (EDCs) are pollutants found throughout the environment that disrupt normal endocrine processes. In mice, penis development is thought to be most susceptible to EDCs during a critical developmental window occurring on embryonic days (E) 15.5-17.5. However, androgen signaling begins on E13.5 when androgen receptor (AR) protein is found in the genitalia and testosterone is circulating. We hypothesize that disrupting androgen signaling prior to the established critical window sensitizes the penis to future androgen disruption. To test this hypothesis, CD1 dams were exposed to vinclozolin or a corn oil solvent control on E13.5 and E14.5 and AR levels were measured with immunohistochemistry on E14.5. Early antiandrogen exposure reduced AR within nuclei and decreased intensity of AR expression within E14.5 genitalia. To evaluate the influence of antiandrogen exposure before the known critical window of penis development, two groups of pregnant dams (n = 3) were exposed to vinclozolin starting at either E13.5 or E14.5 and continued exposure through E16.5. Histology and M.O.U.S.E. scoring were used to quantify penis abnormalities. To account for differences in total doses mice experienced due to differences in length of dosing time, we compared animals that received the same total doses. Exposure to antiandrogens on E13.5 exacerbated malformations when exposure was continued through sexually dimorphic development. Both exposure time and vinclozolin dose are important for severity of vinclozolin-induced penis abnormalities in mice. This work shows that antiandrogen exposure prior to sensitive periods can exacerbate the effects of later antiandrogen exposure on reproductive development.

Developmental and sexual dimorphic atlas of the prenatal mouse external genitalia at the single-cell level

“…While the androgen and estrogen receptor are expressed in the epithelium, epithelialspecific knockouts of the androgen and estrogen receptor have no phenotypic differences from normal mice, which suggests no functional role of epithelial steroid receptors in mice (5). Inhibition of androgen signaling in the male embryos with either genetic knockouts or pharmaceutical and toxicological inhibitors results in formation of the clitoris, the female counterpart of the penis (8)(9)(10). Thus, the female pathway has been identified as the default/passive developmental pathway because it develops in the absence of androgen signaling.…”

One Tool for Many Jobs: Divergent and Conserved Actions of Androgen Signaling in Male Internal Reproductive Tract and External Genitalia

“…For example, the estrogenic chemicals such as estradiol benzoate, diethylstilbesterol, and 17β-estradiol, cause only distal hypospadias ( 70 , 89 , 90 ). The degree of defects in urethra closure drastically differs among different anti-androgen exposure, which induces severe hypospadias where the urethra exits at the base of the penis ( 91 ). ER may be antagonizing AR at hormone response elements along the DNA within the distal ventral glans.…”

“…Inactivation of the androgen signaling, either through global Ar knockout or exposure to environmental chemicals, result in severe aplasia of the prepuce and a lack of fusion along the ventral aspect of the penis ( 70 , 91 ). The majority of hypospadias cases are accompanied with preputial defects ( 96 , 97 ).…”

Endocrine disrupting chemicals in the pathogenesis of hypospadias; developmental and toxicological perspectives

“…Exposures to antiandrogens such as vinclozolin, a fungicide, also cause hypospadias in both mice ( Vilela et al, 2007 ) and rats ( Gray et al, 1999 , Kelce et al, 1994 ). Vinclozolin is regularly used to induce hypospadias in mouse models to investigate the mechanism of antiandrogen action on the development of the urethra ( Amato et al, 2018 , Yang et al, 2019 ). Vinclozolin also affects the sperm epigenome in rats, resulting in long lasting impacts on spermatogenesis across multiple generations ( Beck et al, 2017 , Ben Maamar et al, 2018 , Nilsson et al, 2018 , Schuster et al, 2016 , Skinner et al, 2019 ).…”