Evaluation of uterine oxidative stress in waters through lipid peroxidation and protein oxidation: diagnostic contribution to endometritis

• Grant number: 25/10360-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Eneiva Carla Carvalho Celeghini
• Grantee: Leonardo David Pereira
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Endometritis is one of the main causes of infertility in mares and may be associated with oxidative stress (OS), characterized by an imbalance between reactive oxygen species (ROS) and the body's antioxidant mechanisms. The deposition of semen in the uterus causes an inflammatory response that, in susceptible mares, becomes exacerbated and may evolve into the so-called persistent post-breeding endometritis. This response involves intense release of ROS, which, when unbalanced, promotes OS and compromises the uterine environment. Malondialdehyde (MDA), a byproduct of lipid peroxidation, can be used as a biomarker of OS, as well as protein oxidation. This study aims to evaluate uterine oxidative stress in mares with endometritis in order to contribute to the diagnosis of the disease. For this study, endometrial samples collected from 45 estrous cycles of 15 mares will be used at two time points: T0: immediately before uterine infusion (IU) of extender containing pentoxifylline (to challenge the uterus to an inflammatory response) and T12: 12 hours after IU. The samples will be submitted to uterine cytology evaluation to quantify the percentage of polymorphonuclear cells (PMNs), to MDA dosage using the TBARS technique (thiobarbituric acid reactive substances) to quantify OS and to protein oxidation quantification by detecting carbonyl groups. The MDA and protein oxidation values ¿¿obtained by spectrophotometry will be compared between the groups and correlated with the PMN count in the smears. Mares with a higher inflammatory response are expected to present elevated levels of these markers, evidencing the involvement of oxidative stress in endometritis and reinforcing the importance of their evaluation in the diagnostic context. Based on these results, it is expected to find reference values ¿¿for the diagnosis of endometritis.