Estrogen-Induced Developmental Disorders of the Rat Penis Involve Both Estrogen Receptor (ESR)- and Androgen Receptor (AR)-Mediated Pathways1

Abstract

This study tested the hypothesis that the estrogen receptor (ESR) pathway, androgen receptor (AR) pathway, or both mediate estrogen-induced developmental penile disorders. Rat pups received diethylstilbestrol (DES), with or without the ESR antagonist ICI 182,780 (ICI) or the AR agonist dihydrotestosterone (DHT) or testosterone (T), from Postnatal Days 1 to 6. Testicular T concentration, penile morphology and morphometry, and/or fertility was determined at age 7, 28, or 150 days. DES treatment alone caused 90% reduction in the neonatal intratesticular T surge; this reduction was prevented by ICI coadministration, but not by DHT or T coadministration. Unlike the T surge, coadministration of ICI and coadministration of DHT or T mitigated penile deformities and loss of fertility. Generally, ICI, DHT, or T treatment alone did not alter penile morphology; however, fertility was 20% that of controls in ICI-treated rats vs. 70%-90% in DHT- or T-treated rats. The lower fertility in the rats treated with ICI alone could be due to altered sexual behavior, as these males did not deposit vaginal plugs. In conclusion, observations that both an ESR antagonist and AR agonists prevent penile deformities and infertility suggest that both pathways are involved in estrogen-induced penile disorders. Observations that coadministration of ICI, but not DHT or T, prevents the DES-induced reduction in the neonatal T surge suggest that, although ICI exerts its mitigating effect both at the level of Leydig cells and penile stromal cells, DHT and T do so only at the level of stromal cells.

Estrogen-Induced Maldevelopment of the Penis Involves Down-Regulation of Myosin Heavy Chain 11 (MYH11) Expression, a Biomarker for Smooth Muscle Cell Differentiation1

“…The support for a direct effect comes from observations that estrogen receptors are present in the rat penis at birth [38] and from our observations that estrogen-induced penile maldevelopment was associated with ESR1 up-regulation [39] and was mitigated by ESR antagonist ICI coadministration with estrogen [24]. ESR1 up-regulation was associated with abnormal development of the female reproductive tract [40], mammary gland [41], prostate [42], and seminal vesicles [43] in rodents treated neonatally with estrogens.…”

“…Previously, we reported that adult rats treated neonatally with the antiandrogen GnRH-antagonist [23] or estrogens [24,25] developed similar penile abnormalities, including loss of cavernous spaces and accumulation of fat cells. These abnormalities occurred in animals that were treated with DES before 12 days of age but not after.…”

“…The 6-day treatment was based on our previous data, wherein we showed that 100% of the adult rats or mice treated neonatally for 6 days with DES at a dose of 0.1 mg/kg developed permanently malformed penises and were infertile [26,30]. Similarly, the above doses of ICI and DHT have been shown to mitigate estrogenic effects [24,31]. Tissues were collected following CO 2 asphyxiation of the pups at 7, 10, and 21 days of age.…”

“…Five-micrometer-thick sections were cut, and photographs were taken as described above. In addition to the 7-, 10-, and 21-day-old penis samples, paraffin sections from the body of the adult penis from a previous study [24] were stained for immunohistochemistry and histochemistry. Also, paraffin sections from each group were stained with hematoxylin and eosin.…”

“…For plasma testosterone, a blood sample from the heart of each animal (21-day groups only) was collected just before complete CO 2 asphyxiation, and plasma was collected by centrifugation. Both plasma and testicular samples were frozen at À208C until assayed using a Coat-A-Count testosterone radioimmunoassay (Diagnostics Products Corp., Los Angeles, CA), as described previously from our laboratory [24]. The sensitivity of the assay was 0.2 ng/ml.…”