Theoretical Framework for Understanding the Role of Oxidative Stress Signalling in the Pathogenesis of Bovine Endometritis: Molecular Evidence from Cattle in South West Nigeria

Bovine endometritis is the most prevalent reproductive tract disease of postpartum dairy cattle, and while microbial colonisation is well established as a precipitating cause, the molecular mechanisms by which oxidative stress signalling perpetuates endometrial inflammation and impairs uterine involution remain poorly defined. This study developed and empirically tested a theoretical framework for oxidative stress-mediated endometritis pathogenesis using uterine lavage fluid, endometrial biopsy, and serum samples from postpartum Friesian-Zebu crossbred cows at commercial dairy farms in Ogun and Oyo States, South West Nigeria. A cohort of one hundred and twenty cows was monitored from calving through twelve weeks postpartum, with inflammatory and oxidative biomarker profiling at two, four, six, and twelve weeks. Endometrial reactive oxygen species, nuclear factor kappa-B activation, interleukin-1-beta, interleukin-8, prostaglandin E2, and 8-isoprostane concentrations were quantified using immunoassay and enzyme-linked immunosorbent assay. Structural equation modelling was employed to test the proposed theoretical pathogenesis framework. The model confirmed that nuclear factor kappa-B activation mediates the relationship between oxidative stress markers and inflammatory cytokine production, and that interleukin-8-driven neutrophil infiltration perpetuates epithelial damage. Cows with elevated 8-isoprostane at week two had a significantly higher incidence of cytological endometritis at week four. This study provides the first theory-grounded oxidative stress framework for bovine endometritis in Nigeria and identifies therapeutic targets for intervention. Keywords: bovine endometritis, oxidative stress, nuclear factor kappa-B, interleukin-8, South West Nigeria.