Potential effects of Thymus vulgaris L. on the gene expression of inhibin A, inhibin B, and Aromatase (CYP19A1) in a letrozole-induced PCOS rat model

Background Polycystic ovary syndrome (PCOS) is one of the main causes of infertility in women of reproductive age. Hyperandrogenism and anovulation are common mostly in women with PCOS. Metformin was the first insulin sensitizer to be used in PCOS management to improve ovulation and reduce androgen levels. The currently available medication depends mainly on hormonal therapy such as combined oral contraceptives, anti-androgens, and ovulation-inducing agents, which help regulate menstrual cycles and reduce hyperandrogenism but potentially leading to some complications. However, alternative treatments with special insights into medicinal plants have become reliable and safer approaches with better outcomes. The present study aimed to explore the therapeutic potential of Thymus vulgaris leaves ( Thymus v. ) in a letrozole-induced PCOS rat model compared with that of metformin. Letrozole-induced PCOS rats were treated with total Thymus v. extract in a dose-dependent manner (50, 75 and 100 mg/kg) and with metformin orally for 14 consecutive days. HPLC–PDA-ESI–MS/MS was used for the phytochemical characterization of the bioactive extract. Results Treatment with the different doses resulted in a significant decrement of the gene expression levels of inhibin A, inhibin B and CYP19A1, which was further confirmed by immunohistochemistry. Additionally, Thymus v. restored hormonal equilibrium by modulating steroidogenic enzymes (estrogen, progesterone and testosterone), specifically by tuning gonadotropin levels and correcting the LH-to-FSH. The restoration of the normal morphological architecture of ovaries and follicular growth was supported by histopathological examination. Conclusion This study provides insights into the mechanistic impact of Thymus v . as a multifaceted therapeutic nutraceutical in hormonal and molecular imbalances in PCOS.