Vitamin K₂ (MK-7) as a novel cytoprotective agent in ovarian ischemia-reperfusion: Promoting functional recovery

Ovarian torsion is a typical surgical emergency in gynecology. Ovarian torsion-detorsion (T/D) causes ischemia-reperfusion injury characterized by excessive oxidative stress, inflammation, and apoptosis, ultimately impairing ovarian structure and function. Vitamin K2 (menaquinone-7, MK-7) has antioxidant and anti-inflammatory properties and may provide pharmacological protection against ischemic tissue damage. This study aimed to evaluate the protective effects of MK-7 against ovarian T/D injury in a rat model.

Thirty-two mature female Wistar rats were randomly allocated into four experimental groups (n = 8 per group): control, sham-operated, torsion/detorsion (T/D), and MK-7-treated T/D. Ovarian torsion was induced under anesthesia and maintained for 2 h. Postoperative treatment consisted of MK-7 (30 mg/kg) administered via oral gavage. Dosing commenced 4 h after surgery and continued once daily for 7 days. Blood and ovarian tissue specimens were collected at the end of the treatment period for analysis. ELISA measured serum anti-Müllerian hormone (AMH) levels. Oxidative stress markers-malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT)-and inflammatory cytokines (interleukin-1β [IL-1β], interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]) were quantified using commercial ELISA kits. Ovarian tissue mRNA expression of B-cell lymphoma 2 (BCL-2), BCL-2-associated X protein (BAX), caspase-3, p53, and AMH was assessed by quantitative real-time PCR. Protein expression of sirtuin 1 (SIRT1) and nuclear factor kappa-light-chain-enhancer of activated B cells p65 (NF-κB p65) was evaluated by immunohistochemistry. At the same time, histopathological changes were examined using hematoxylin-eosin (H&E), periodic Acid-Schiff (PAS), and Masson's trichrome (MT) staining.

Ovarian T/D significantly elevated oxidative stress and inflammation, as evidenced by elevated MDA (p < 0.001), TNF-α (p < 0.01), and IL-6 (p < 0.001), along with significant activation of apoptotic signaling, reflected by increased BAX (p < 0.01) and caspase-3 expression (p < 0.001). Moreover, it upregulated NF-κB p65 expression (p < 0.001). Concurrently, it impaired antioxidant defenses through reduced SOD (p < 0.01) and GSH-Px activities (p < 0.001), lowered AMH levels (p < 0.01), suppressed the anti-apoptotic protein BCL-2 (p < 0.01) and SIRT1 (p < 0.001), and led to pronounced histopathological injury, including follicular atresia, interstitial edema, and fibrosis. Conversely, MK-7 treatment at 30 mg/kg significantly attenuated markers of oxidative stress and inflammation, shown by decreased MDA, TNF-α, and IL-6, decreased BAX (p < 0.01), caspase-3 (p < 0.001), and NF-κB p65 expression (p < 0.001), elevated antioxidant capacity by increasing SOD and GSH-Px activities, upregulated SIRT1 (p < 0.01) and BCL-2 (p < 0.01), and increased AMH levels (p < 0.001). These effects were accompanied by preservation of follicular architecture and a substantial reduction in interstitial damage.

MK-7 attenuates ovarian I/R injury by restoring antioxidant defenses and suppressing oxidative, inflammatory, and apoptotic pathways via SIRT1 upregulation and NF-κB p65 downregulation, positioning it as a promising therapeutic agent for ovarian I/R protection.