Developmental Programming: Prenatal Steroid Excess Disrupts Key Members of Intraovarian Steroidogenic Pathway in Sheep

Abstract

Prenatal testosterone (T) excess disrupts ovarian cyclicity and increases circulating estradiol levels as well as follicular recruitment and persistence culminating in multifollicular ovary similar to women with polycystic ovary syndrome. We tested whether prenatal T excess, by androgenic or estrogenic action, disrupts the steroid biosynthetic machinery in sheep in a cell-, follicle stage-, age-, and treatment-specific manner consistent with the ovarian disruptions and increased estradiol release. Impact of T/dihydrotestosterone (DHT) treatments from days 30-90 of gestation on steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase, cytochrome P-450 17α-hydroxylase/C17, 20-lyase (CYP17A1), and cytochrome P-450 aromatase (CYP19A1) were examined on fetal day 90, 140 and 10 months (postpubertal), and 21 months (adult, no DHT group) of age by immunohistochemistry. All 4 markers changed in a cell-, follicle stage-, and age-specific manner. Both treatments increased steroidogenic acute regulatory protein expression in preantral follicles of postpubertal and adult females. Effects of prenatal T and DHT on 3β-hydroxysteroid dehydrogenase differed in a follicle- and age-specific manner. CYP17A1 was reduced in the theca interna of antral follicles by T, but not DHT, in 10- and 21-month-old females. CYP19A1 was reduced by both T and DHT at all ages barring an increase on fetal day 140. Reduced granulosa CYP19A1 and thecal CYP17A1 in adults likely disrupt the intrafollicular androgen/estrogen balance contributing to follicular persistence. The reduced thecal CYP17A1 expression suggests that the hyperandrogenic ovarian phenotype may originate from increased enzyme activity or alternatively via a different isoform of CYP17. The reduced CYP19A1 in antral follicles of adults indicates that the increased circulating estradiol release likely arises from the increased number of persisting follicles.

DNA methylation in the pathogenesis of polycystic ovary syndrome

“…Intrauterine programming has been proposed as one of the plausible mechanisms that cause PCOS, as evidenced by the high heritability of the disease and animal models demonstrating that prenatal exposure to high levels of androgens or AMH results in the acquisition of the PCOS phenotype in the offspring (Filippou & Homburg 2017, Tata et al 2018. To date, several studies have been conducted in prenatal androgenized sheep and monkeys in which a PCOS phenotype was observed during adulthood, which, in turn, has been related to DNA methylation changes in the case of monkeys (Manikkam et al 2006, Abbott et al 2008, Veiga-Lopez et al 2008, 2012, Smith et al 2009, Ortega et al 2010, Xu et al 2011, Padmanabhan et al 2014, Puttabyatappa et al 2018. Nevertheless, little…”

“…These molecular and morphological changes in the ovarian tissue could be attributed to epigenetic alterations as proposed in animal models of PCOS. Predominantly, studies have reported that prenatal testosterone treatment in sheep results in an increase in the occurrence of persistent and growing follicles (contributing to the morphology of a PCO), luteal and antral follicles defects, a decline in primordial follicles and an altered ovarian protein content of AMH, ovarian steroidogenic enzymes, matrix metalloproteases and proteins related to insulin pathway during adulthood (Manikkam et al 2006, Veiga-Lopez et al 2008, 2012, Smith et al 2009, Ortega et al 2010, Padmanabhan et al 2014, Puttabyatappa et al 2018. Remarkably, this fetal programming induced by prenatal testosterone correlates with defects in the expression of ovarian steroidogenic genes and miRNAs associated with insulin pathway in the ovaries of fetal ewes (Luense et al 2011).…”

“…The aromatase activity is decreased in patients with PCOS, perhaps, by an increase of androgens in circulation and follicular fluid (Chen et al 2015, Yang et al 2015. Reportedly, prenatal testosterone treatment downregulates the expression of aromatase in granulosa cells from adult sheep (Padmanabhan et al 2014), indicating that the increase in DNA methylation in CYP19A1 promoter observed in women with PCOS could be the result of the prenatal exposure to high levels of androgens. Most studies focusing on DNA methylation and PCOS have been conducted in granulosa cells, which play a fundamental role in steroidogenesis and ovarian folliculogenesis and whose dysfunction correlates with the pathogenesis of the disease (Pellatt et al 2007;Lan et al 2015).…”

Steroidogenic versus Metabolic Programming of Reproductive Neuroendocrine, Ovarian and Metabolic Dysfunctions

“…The thecal androgen production could also be influenced by LH hypersecretion [44, 45, 96]. Although the reduced expression of the enzyme CYP17A1 in the theca interna of antral follicles in prenatal T-treated sheep [97] is inconsistent with hyperandrogenism, this may be offset by an increase in the activity of this enzyme, compensatory induction of another isoform, or autocrine/paracrine feedback inhibition [97, 98]. However, gestational T increases AR in these follicles supporting functional hyperandrogenism [39].…”

Expression of steroidogenic enzymes and steroid receptors in foetal gonads of domestic cat—Sex similarities and differences

“…Foetal gonads are already able to produce and secrete steroid hormones, which are important for the foetal programming of sexual development and reproductive function, for example the development of internal and external genitalia (Kucinskas & Just, ; Padmanabhan, Salvetti, Matiller, & Ortega, ). In steroid biogenesis, many enzymes are engaged (Miller, ); the pathway for reproductive steroid hormone synthesis and the enzymes involved are delineated in Figure .…”