OR31-05 Emergence of Ovarian Hyperandrogenism and Luteal Insufficiency Following ESR1 Knockdown in the Mediobasal Hypothalamus of Adult Female Rhesus Monkeys

Abstract

Diminished estradiol (E2) negative feedback action by neuronal ESR1 in the arcuate nucleus (ARC) of the mediobasal hypothalamus (MBH) is hypothesized to cause gonadotropin-releasing hormone (GnRH) hypersecretion, and thus LH excess, contributing to ovarian hyperandrogenism in polycystic ovary syndrome (PCOS). In primates, including humans, however, the mediating estrogen receptor is unknown. Thus, to test the hypothesis that diminished E2 action on ARC ESR1 contributes to female primate ovarian hyperandrogenism, eleven, ovary intact, adult female rhesus macaques, pair housed with female peers, received five 12µl MRI-guided MBH infusions into the rostral-to-caudal extent of both right and left ARC. Each infusion comprised gadolinium contrast agent and ~3-4 x 1010 adeno-associated virus 8 (AAV8) particles containing either a shRNA specific for ESR1 (n=6, ERaKD) or scrambled shRNA (n=5, control). Mid-surgery MRI scans identified targeting accuracy. 2-2.5 years following AAV8 infusion, EIA-determined P4 values were obtained from twice weekly serum samples; samples obtained during the follicular phase of menstrual cycles or anovulatory periods were submitted to liquid chromatography, tandem mass spectrometry (LCMS) for additional steroid hormones. LCMS-determined values were also obtained 0 hours (h) and 24 h following an IM injection of 200IU hCG. Both ERaKD (28.5 ± 1.3 days, mean ± SEM) and control (34.0 ± 3.3 days) female groups exhibited comparably regular menstrual cycles. ERaKD exhibited higher circulating levels of LH (2.8 ± 0.2 ng/ml, p=0.03), androstenedione (A4, 0.43 ± 0.03 ng/ml, p=0.03) and testosterone (T, 0.23 ± 0.03 ng/ml, p=0.09), and LH/FSH ratio (1.7 ± 0.2, p=0.05) compared to controls (LH, 2.1 ± 0.4; A4, 0.30 ± 0.05; T, 0.18 ± 0.01 ng/ml; LH/FSH 1.3 ± 0.2). Following an ovarian androgen-stimulating hCG injection, ERaKD 24-h peak levels for T (0.28 ± 0.01 ng/ml) were higher (p=0.03) compared to controls (0.21 ± 0.01 ng/ml). In addition, luteal insufficiency emerged in ERaKD females, with mean (2.4 ± 0.3 ng/ml), peak (3.6 ± 0.4 ng/ml) and area-under-the-curve (AUC, 23.2 ± 4.2 ng/ml/days) P4 values diminished compared to controls (mean, 3.6 ± 0.1, p=0.01; peak 5.7 ± 0.1 ng/ml, p=0.01; AUC, 43.7 ± 6.7 ng/ml/days, p=0.03). Taken together, these results suggest that knockdown of ARC ESR1 disrupts Gn stimulation of ovarian function, contributing to female monkey ovarian hyperandrogenism and menstrual cycle impairment emulating PCOS in women.