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Excess levels of circulating androgens during prenatal or peripubertal development are an important cause of polycystic ovary syndrome (PCOS), with the brain being a key target. Approximately half of the women diagnosed with PCOS also experience metabolic syndrome; common features including obesity, insulin resistance and hyperinsulinemia. Although a large amount of clinical and preclinical evidence has confirmed this relationship between androgens and the reproductive and metabolic features of PCOS, the mechanisms by which androgens cause this dysregulation are unknown. Neuron-specific androgen receptor knockout alleviates some PCOS-like features in a peripubertal dihydrotestosterone (DHT) mouse model, but the specific neuronal populations mediating these effects are undefined. A candidate population is the agouti-related peptide (AgRP)-expressing neurons, which are important for both reproductive and metabolic function. We used a well-characterised peripubertal androgenized mouse model and Cre-loxP transgenics to investigate whether deleting androgen receptors specifically from AgRP neurons can alleviate the induced reproductive and metabolic dysregulation. Androgen receptors were co-expressed in 66% of AgRP neurons in control mice, but only in <2% of AgRP neurons in knockout mice. The number of AgRP neurons was not altered by the treatments. Only 20% of androgen receptor knockout mice showed rescue of DHT-induced androgen-induced anovulation and acyclicity. Furthermore, androgen receptor knockout did not rescue metabolic dysfunction (body weight, adiposity or glucose and insulin tolerance). While we cannot rule out developmental compensation in our model, these results suggest peripubertal androgen excess does not markedly influence Agrp expression and does not dysregulate reproductive and metabolic function through direct actions of androgens onto AgRP neurons., (© 2024 The Authors. Journal of Neuroendocrinology published by John Wiley & Sons Ltd on behalf of British Society for Neuroendocrinology.)

Polycystic ovary syndrome (PCOS) is one of the most common causes of infertility in women. Approximately half of the diagnosed individuals also experience the metabolic syndrome. Central and peripheral resistance to the hormones insulin and leptin have been reported to contribute to both metabolic and reproductive dysregulation. In PCOS and preclinical PCOS animal models, circulating insulin and leptin levels are often increased in parallel with the development of hormone resistance; however, it remains uncertain whether these changes contribute to the PCOS state. In this study, we tested whether central actions of protein tyrosine phosphatase 1B (PTP1B) and suppressor of cytokine signaling 3 (SOCS3), negative regulators of insulin and leptin signaling pathways, respectively, play a role in the development of PCOS-like phenotype. A peripubertal dihydrotestosterone (DHT) excess PCOS-like mouse model was used, which exhibits both metabolic and reproductive dysfunction. Mice with knockout of the genes encoding PTP1B and SOCS3 from forebrain neurons were generated, and metabolic and reproductive functions were compared between knockout and control groups. DHT treatment induced mild insulin resistance but not leptin resistance, so the role of SOCS3 could not be tested. As expected, DHT excess abolished estrous cycles and corpora lutea presence and caused increased visceral adiposity and fasting glucose levels. Knockout mice did not show any rescue of reproductive dysfunction but did have reduced adiposity compared to the control DHT mice. These data suggest that negative regulation of central insulin signaling by PTP1B is not responsible for peripubertal DHT excess-induced reproductive impairments but may mediate its increased adiposity effects.

Polycystic ovarian syndrome (PCOS) is the leading cause of anovulatory infertility and is a heterogenous condition associated with a range of reproductive and metabolic impairments. While its etiology remains unclear, hyperandrogenism and impaired steroid negative feedback have been identified as key factors underpinning the development of PCOS-like features both clinically and in animal models. We tested the hypothesis that androgen signaling in kisspeptin-expressing neurons, which are key drivers of the neuroendocrine reproductive axis, is critically involved in PCOS pathogenesis. To this end, we used a previously validated letrozole (LET)-induced hyperandrogenic mouse model of PCOS in conjunction with Cre-lox technology to generate female mice exhibiting kisspeptin-specific deletion of androgen receptor (KARKO mice) to test whether LET-treated KARKO females are protected from the development of reproductive and metabolic PCOS-like features. LET-treated mice exhibited hyperandrogenism, and KARKO mice exhibited a significant reduction in the coexpression of kisspeptin and androgen receptor mRNA compared to controls. In support of our hypothesis, LET-treated KARKO mice exhibited improved estrous cyclicity, ovarian morphology, and insulin sensitivity in comparison to LET-treated control females. However, KARKO mice were not fully protected from the effects of LET-induced hyperandrogenism and still exhibited reduced corpora lutea numbers and increased body weight gain. These data indicate that increased androgen signaling in kisspeptin-expressing neurons plays a critical role in PCOS pathogenesis but highlight that other mechanisms are also involved., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Endocrine Society.)