Estrogen-Induced Abnormal Accumulation of Fat Cells in the Rat Penis and Associated Loss of Fertility Depends upon Estrogen Exposure during Critical Period of Penile Development

Abstract

We previously reported that diethylstilbestrol (DES) or estradiol valerate (EV) exposure at a dose of 0.10-0.12 mg/kg, or higher, per day, on alternate days, from postnatal days 2-12, resulted in abnormal penis development and infertility (H. O. Goyal et al., 2005, J. Androl. 26, 32-43). The objective of this study was to identify a critical developmental period(s) during which EV exposure results in the observed penile abnormalities. Male pups received EV at a dose of 0.10-0.12 mg/kg on postnatal day(s) 1, 1-3, 4-6, 1-6, 7-12, 13-18, 19-24, or 25-30. Fertility was tested at 102-115 days of age and tissues were examined at 117-137 days. Both penile morphology and fertility were unaltered in rats treated with EV after 12 days of age. Conversely, except in rats treated on postnatal day 1 only, none of the males treated prior to 12 days of age sired pups, and all had abnormal penises, including varying degrees of abnormal accumulation of fat cells and loss of cavernous spaces and smooth muscle cells in the corpora cavernosa penis, which were maximal in the 1-6-day group. Also, the preputial sheath was partially released or its release was delayed, and the weight of the bulbospongiosus muscle was significantly reduced. Plasma testosterone (T) in the 1-6- and 4-6-day groups and intratesticular T in the 4-6-day group were significantly lower. The testosterone surge, characteristic of controls in the first week of life, was suppressed in the 1-3-day group. Estrogen receptor alpha mRNA expression was enhanced in the body of the penis in the 1-3-day group, but not in the 13-18-day group. Hence, EV exposure prior to 12 days of age (as short as 1-3 days postnatal), but not after 12 days of age, results in long-term abnormal penile morphology, characterized by abnormal accumulation of fat cells in the corpora cavernosa penis and, consequently, loss of fertility.

Estrogen receptor-α mediates estrogen-inducible abnormalities in the developing penis

“…In agreement with our previous observations in the rat (Goyal et al 2005b), the weight of both penile skeletal muscles, bulbospongiosus and levator ani was not only significantly decreased but also was differentially decreased, with the former muscle undergoing a much higher decrease, as a result of neonatal estrogen exposure to wild-type mice. The mechanism of this differential decrease may lie in differences in androgen receptor concentration because both muscles are androgen dependent (Breedlove & Arnold 1983, Hadi Mansouri et al 2003 and, interestingly, both muscles are more developed in ERaKO mice than in wild-type/ control mice.…”

“…Although neonatal DES exposure in the present study did not significantly alter the adult level of plasma or intratesticular testosterone in wild-type mice, the neonatal level of intratesticular testosterone in rat pups treated with DES for 1-3 postnatal days was reduced by 90% at postnatal days 5-8 (Goyal et al 2005b), the developmental period when stromal cells start differentiation in the rat penis (Murakami 1986(Murakami , 1987, thus suggesting a role for estrogen-induced lower androgen action in inducing penile abnormalities by reprogramming stromal cell differentiation. In this context, observations that endogenous estrogens or DES exposure to fetal or neonatal Leydig cells decreased testosterone secretion in wild-type mice, but not in ERaKO mice, implied an ERa-mediated inhibitory role of estrogen in testosterone secretion (Delbes et al 2005).…”

“…One potential mechanism by which neonatal estrogen exposure induces developmental abnormalities may involve an activation of ERa-mediated signaling because we previously found an association between ERa upregulation and penile abnormalities in the developing rat penis treated neonatally with DES (Goyal et al 2004b(Goyal et al , 2005b. Similarly, ERa upregulation is associated with abnormal development of rodent female reproductive tract (Yamashita et al 1990, Markey et al 2005, mammary gland (Tekmal et al 2005), male reproductive tract (Sato et al 1994), prostate gland (Prins & Birch 1997, and seminal vesicles .…”

“…Reasons for this difference may be attributed to differences in the species, or to the developmental stage of the penis at the time of estrogen exposure, because, even within the rat, the severity of loss of smooth muscle cells and cavernous spaces and the degree of accumulation of fat cells was higher in the penis exposed to estrogen from postnatal days 1 to 6 than that exposed from postnatal days 7 to 12 ERa mediates penile abnormalities (Goyal et al 2005b). Considering that the length of gestation is shorter in mice than rats (19-21 days vs 21-23 days), it is logical to suggest that stromal cells at birth are at a more advanced stage of differentiation in the mouse penis than the rat penis and thus this difference may be a factor in the differential response observed in the penis of these two species.…”

Testosterone and Erectile Function: From Basic Research to a New Clinical Paradigm for Managing Men with Androgen Insufficiency and Erectile Dysfunction

“…Specifically, bisphenol A has been shown to accelerate terminal differentiation of 3T3L1 fibroblasts into adipocytes through the PI 3 kinse pathway [34]. Interestingly, in developmental studies, Goyal et al [35][36][37][38] have shown that administration of estradiol valerate or the estrogen receptor agonist diethylstilbestrol into 2-day-old rats resulted in infertile mature animals (120 d) and accumulation of fat-containing cells in the penile corpus cavernosum. In contrast, animals treated with vehicle exhibited no fat-containing cells and remained fertile.…”