Female sexual behavior is disrupted in a preclinical mouse model of PCOS via an attenuated hypothalamic nitric oxide pathway

Women with polycystic ovary syndrome (PCOS) frequently experience decreased sexual arousal, desire, and sexual satisfaction. While the hypothalamus is known to regulate sexual behavior, the specific neuronal pathways affected in patients with PCOS are not known. To dissect the underlying neural circuitry, we capitalized on a robust preclinical animal model that reliably recapitulates all cardinal PCOS features. We discovered that female mice prenatally treated with anti-Müllerian hormone (PAMH) display impaired sexual behavior and sexual partner preference over the reproductive age. Blunted female sexual behavior was associated with increased sexual rejection and independent of sex steroid hormone status. Structurally, sexual dysfunction was associated with a substantial loss of neuronal nitric oxide synthase (nNOS)-expressing neurons in the ventromedial nucleus of the hypothalamus (VMH) and other areas of hypothalamic nuclei involved in social behaviors. Using in vivo chemogenetic manipulation, we show that nNOS^VMH neurons are required for the display of normal sexual behavior in female mice and that pharmacological replenishment of nitric oxide restores normal sexual performance in PAMH mice. Our data provide a framework to investigate facets of hypothalamic nNOS neuron biology with implications for sexual disturbances in PCOS.

Polycystic ovary syndrome (PCOS) is a highly prevalent disease affecting 5 to 18% of women of reproductive age worldwide (1, 2). PCOS is diagnosed upon the presence of at least two out of three prime features: high circulating levels of androgens (hyperandrogenism), menstrual irregularities (oligo-anovulation), and polycystic-like ovarian morphology (2, 3). Beyond its implications leading to female infertility, the disease is associated with several metabolic disruptions, cardiovascular diseases, and psychosocial disorders (4). Among these neurological implications, it has become clear that approximately 30% or more of patients with PCOS experience sexual dysfunctions, with clinical studies reporting a high risk of low sexual arousal, desire, and satisfaction and impaired lubrication and orgasm (5–9). These symptoms allude to disturbances in brain circuits controlling sexual function in the context of PCOS.Neural circuits driving female sexual behaviors are conserved among vertebrate species operating under the influence of sex steroid hormone modulation, which is paramount for partner interaction, receptivity, and sexual performance (10, 11). Indeed, gonadal sex hormones are implicated in shaping circuit architecture in the hypothalamus during development and activating these neonatally programmed circuits over reproductive adult life in many species (12–16). The hypothalamus integrates sensorial stimuli and autonomic arousal from endogenous sex drive cues (e.g., estrous phase, energy status, hormone milieu, genital stimulation) to convey this information to other brain areas and peripheral nerves (10, 17). The ventromedial nucleus of the hypothalamus (VMH) is considered the hub of specialized neurons, with intrinsic properties driving different components of sexual behavior (18–21). The VMH harbors neurons expressing neuronal nitric oxide synthase (nNOS), the enzyme responsible for the production of nitric oxide (NO), a key gaseous neurotransmitter that stimulates female sexual behavior (22, 23) and communicates with other circuits within the social brain (24, 25). Despite current advances unraveling novel pathways in the female sexual brain with specific behavioral responses, there is a clear lack of knowledge on how disturbances in these circuits may participate in sexual dysfunctions affecting one-third of women with PCOS.Growing evidence indicates that androgen excess in utero induces a developmental reprogramming of the female fetal brain toward the manifestation of PCOS traits later in life (26–29). Some studies have suggested that the clinical signs of hyperandrogenism have detrimental sexual effects (5), indicating a negative correlation between androgen levels and sexual function in PCOS. In recent years, it has been proposed that prenatal anti-Müllerian hormone excess may trigger gestational hyperandrogenism via the inhibition of placental aromatase (29, 30) and that women with PCOS display higher circulating levels of androgens and AMH during pregnancy as compared to healthy women (29, 31). Prenatal AMH-treated mice (PAMH) reliably recapitulate all the mouse equivalents of the PCOS Rotterdam criteria (29, 32) and are thus a preclinical model to mimic the human PCOS condition. PAMH female mice also display pronounced neuroendocrine dysfunction leading to exacerbated luteinizing hormone (LH) secretion (29), as in women with PCOS (33), denoting the presence of prenatally reprogrammed defects within the gonadotropin-releasing hormone (GnRH) neuronal network. Thus, prenatal AMH excess–mediated disruptions in the female brain may be key to understanding the pathophysiology of PCOS.Here, we investigated whether prenatal AMH excess could underpin defects in sex circuits promoting sexual dysfunction in PCOS-like female mice. We uncovered a profound decrease of nNOS and progesterone receptor (PR) expression in the VMH. These anatomical changes were also associated with significant impairment of sexual receptivity in PCOS-like female mice. Nevertheless, normal sexual function in PAMH female mice was restored to control levels upon peripheral injection of NO donor. Performing a series of acute functional manipulations in freely moving female mice, we showed that chemogenetic silencing of nNOS^VMH neurons in control female mice recapitulates PCOS-like sexual dysfunctions. Taken together, we unveiled a brain pathway potentially underpinning the etiology of low sexual drive in PCOS while pointing to prospective therapeutic approaches to rescue normal sexual function in these women.