Adrenal AKR1C3-mediated androgen activation contributes to hyperandrogenism in prepubertal ovariectomized rats

Hyperandrogenism during childhood is a key feature of several pediatric endocrine disorders, including premature adrenarche and polycystic ovary syndrome (PCOS). The adrenal gland contributes significantly to circulating androgens, yet the regulation of adrenal steroidogenic enzymes during the prepubertal period remains poorly understood. This study aimed to investigate adrenal androgen synthesis in a prepubertal rat model of ovarian removal and identify key enzymes responsible for hyperandrogenism.

Female Sprague-Dawley rats underwent either ovariectomy or sham surgery on postnatal day (PND) 15. Serum steroid hormone levels were measured by enzyme-linked immunosorbent assay (ELISA). Adrenal tissue was analyzed by RNA sequencing to screen for differentially expressed genes (DEGs) involved in steroidogenesis; findings were subsequently validated by quantitative real-time polymerase chain reaction (qPCR), western blot, and immunohistochemistry (IHC). The functional role of a candidate gene in steroid synthesis was assessed through in vitro overexpression and in vivo pharmacological inhibition.

Serum testosterone levels increased on PND 25 and 30 after ovariectomy, whereas dehydroepiandrosterone (DHEA) concentrations decreased. Transcriptomic analysis revealed that adrenal AKR1C3 was the most significantly DEG between OVX and sham-operated controls. Its expression was elevated in OVX rats from PND 25 to PND 30, as confirmed by qPCR, western blot, and IHC. In vitro, AKR1C3 overexpression converted exogenous androstenedione to testosterone. Conversely, in vivo administration of the AKR1C3 inhibitor ASP9521 (2 mg/kg.day) to OVX rats reduced serum testosterone levels. Additionally, adrenal expression of CYP17A1, another key enzyme in androgen biosynthesis, was also increased in OVX rats from PND 25 to 30.

This study demonstrates that prepubertal ovarian removal upregulates adrenal AKR1C3 and CYP17A1, leading to enhanced adrenal androgen synthesis and systemic hyperandrogenism. These findings provide mechanistic insights into adrenal-derived hyperandrogenism with potential clinical implications for pediatric endocrine disorders such as premature adrenarche and PCOS.