Developmental programming: prenatal androgen excess disrupts ovarian steroid receptor balance

Abstract

Steroid hormones play an important role in reproduction and the receptors through which they signal change in a developmental time, follicle stage, and cell-specific manner. Disruption in steroid receptor expression affects follicle formation and differentiation. In this study, using prenatal testosterone (T) and dihydrotestosterone (DHT)-treated female sheep as model systems we tested the hypothesis that prenatal androgen excess disrupts the developmental ontogeny of ovarian steroid receptor protein expression. Pregnant Suffolk ewes were injected twice weekly with T propionate or DHT propionate (a non-aromatizable androgen) in cottonseed oil from day 30 to 90 of gestation. Changes in ovarian estrogen receptors (ERα, ERβ), androgen receptor (AR) and progesterone receptor (PR) proteins were determined at fetal (day 90 and 140), postpubertal (10 months) and adult (21 months; only prenatal T-treated sheep studied) ages by immunohistochemistry. Prenatal T and DHT treatment induced selective increase in AR but not ER or PR expression in the stroma and granulosa cells of fetal day 90 and 140 ovaries. An increase in ERα and decrease in ERβ immunostaining coupled with increased AR expression were evident in granulosa cells of antral follicles of 10 and 21-month old prenatal T but not DHT-treated females (analyzed only at 10 months). These findings provide evidence that an early increase in ovarian AR is the first step in the altered ovarian developmental trajectory of prenatal T-treated females and manifestation of postnatal ovarian dysfunction are likely facilitated via altered equilibrium of antral follicular granulosa cell ER / AR protein expression.

Disorders of follicle development and steroidogenesis in ovaries of androgenised foetal sheep

“…These results are consistent with those of a previous study by Ortega et al, which reported enhanced protein expression of AR in the foetal ovary of Suffolk sheep, in that case detected by optical density (Ortega et al 2009). The inability to detect differences in AR mRNA levels between PA and control ovaries is consistent with the findings of Hogg et al (2011) in Scottish Greyface sheep.…”

Cytoskeletal proteins in the follicular wall of normal andcystic ovaries of sows

“…The major strength of the well-validated imaging approach used in this study is the visualization of in situ localization of proteins within cells of interest. Quantification of biological markers using this approach has been successfully applied to quantify immunoreactivity in different tissues (Lejeune et al2008, Ortega et al 2009a). This type of densitometrical methodology has been previously validated by biochemical methods of protein induction and quantification (Peretti-Renucci et al 1991).…”

HOXA10 expression is decreased by testosterone in luteinized granulosa cells in vitro

“…The mechanism by which hyperandrogenemia could be linked to increased miscarriage risk is not known. The specific cytokine profile of PCOS patients is likely to be related to the lower implantation rate, since follicular fluid appears to function as an embryotrophic agent (35,36). Certain studies have revealed higher levels of testosterone in the follicular fluid of patients with PCOS (37,38).…”

“…Hyperandrogenism in PCOS may proceed via dysregulated paracrine/endocrine control of androgen synthesis (37), or result from adrenal androgen excess (39,40). Intraovarian androgens have been found to promote GC proliferation and inhibit GC apoptosis in PCOS patients, particularly in small follicles whose GCs are rich in androgen receptors (35,36), indicating that androgens may have a crucial effect on GC development, and intraovarian androgen may play an important role in the pathogenesis of PCOS via regulating early follicle growth. In this study, we observed that excess androgen decreased the expression of the examined HOXA10 genes in GCs, which suggests that androgenic regulation of these genes may specifically contribute to folliculogenesis.…”