Selenium Alleviates Oxidative Stress and Inflammation to Promote Postpartum Uterine Recovery via GPX1/GPX4/NRF2 Pathway in Mice

Background: Selenium is an important trace element that plays crucial roles in metabolism, immune function, and antioxidant defense. As an antioxidant, selenium helps to alleviate postpartum uterine inflammation and promotes uterine recovery. However, the exact mechanism underlying the role of selenium in postpartum uterine recovery is not fully understood. Objective: This study aimed to identify the underlying mechanism and examine how selenium enhances postpartum uterine healing. Methods: Female ICR mice aged 8 weeks were classified into five groups: control, postpartum model, low-dose selenium (100 nm), medium-dose selenium (200 nm), and high-dose selenium (400 nm). Endometrial morphology was evaluated by hematoxylin and eosin (H&E) staining. Oxidative stress markers, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and malondialdehyde (MDA), and inflammatory factors, including tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), were measured using commercially available kits. GPX1, GPX4, and nuclear factor erythroid 2-related factor 2 (NRF2) expression were determined using real-time PCR and WB. Results: We found damage and bleeding points in the endometrium and destruction of the ultrastructure of endometrial cells in the postpartum model group; however, mice treated with a high dose (400 nm) of selenium showed alleviated levels of pathological alteration in the endometrium. In addition, the levels of MDA in the postpartum mice group increased, while the SOD, CAT, and GPX levels decreased; however, changes in these oxidative stress markers were reversed after selenium treatment. For inflammatory factors, high levels of TNF-α and IL-1β were observed in postpartum mice, whereas they were decreased in selenium-treated groups. GPX1, GPX4, and NRF2 expression were reduced in postpartum model mice, but upregulated in selenium- treated mice. Conclusion: Selenium supplementation ameliorated postpartum uterine oxidative stress and inflammation and promoted uterine recovery via the GPX1/GPX4/NRF2 pathway in mice.