Formononetin ameliorates polycystic ovary syndrome through suppressing NLRP3 inflammasome.

Background: Polycystic ovary syndrome (PCOS) is a common gynecological disease accompanied by multiple clinical features, including anovulation, hyperandrogenism, and polycystic ovarian morphology, leading to infertility. Formononetin (FMN), which is a major bioactive isoflavone compound in Astragalus membranaceus, exerts anti-inflammatory effects. However, whether FMN is effective in the treatment of PCOS remains unknown. This study aims to explore the effects and the possible mechanisms of FMN in PCOS.

Methods: Dehydroepiandrosterone (DHEA)-induced PCOS rats and dihydrotestosterone (DHT)-induced PCOS cell models were established. Fifty rats were randomly assigned into five groups of 10 rats each: Control, PCOS, PCOS + FMN (15 mg/kg), PCOS + FMN (30 mg/kg), and PCOS + FMN (60 mg/kg). Fasting blood glucose, insulin, luteinizing hormone, follicle-stimulating hormone, testosterone, and estradiol were detected in DHEA-induced PCOS rats. Ovarian histological changes and apoptosis were evaluated utilizing H&E and TUNEL staining. Subsequently, the effects of FMN on oxidative stress and inflammatory responses in the DHEA-induced PCOS rat model and DHT-induced PCOS cell model were explored. Besides, the function of FMN on cell viability and apoptosis in DHT-induced PCOS cell model were explored by using CCK-8 assay and flow cytometry. Protein expression was detected via western blot and immunofluorescence staining in the DHEA-induced PCOS rat model and DHT-induced PCOS cell model.

Results: FMN alleviated PCOS symptoms and reduced inflammation, cell apoptosis, and oxidative stress in DHEA-induced PCOS rats and DHT-induced KGN cells. Additionally, FMN suppressed NLRP3 inflammasome activation in both models. In the DHT-induced PCOS cell model, nigericin (a activator of NLRP3) reversed the functions of FMN on inflammation, apoptosis, and oxidative stress.

Conclusion: These findings demonstrated that FMN could alleviate PCOS by repressing inflammation, apoptosis, as well as oxidative stress in vivo and in vitro via inhibition of the NLRP3 inflammasome.

Highlights: 1. FMN improved PCOS symptoms. 2. FMN alleviated cell apoptosis, inflammation and oxidative stress in PCOS. 3. FMN inhibited the activation of NLRP3 inflammasome in PCOS.