Oxidative Stress and Inflammation in Sows with Excess Backfat: Up-Regulated Cytokine Expression and Elevated Oxidative Stress Biomarkers in Placenta

In sows, excess backfat during late gestation is associated with improved farrowing difficulties and influences the fetus, but the impact of backfat thinness on placental inflammation, oxidative stress and vascular development has not been defined. In this study, 120 sows were divided into six groups based on backfat thickness (≤ 16, 17–18, 19–20, 21–22, 23–24, and ≥ 25 mm) at late of gestation. The placental lipids, reactive oxygen species (ROS), malondialdehyde (MDA) and total antioxidant capacity (TAC) levels, inflammatory-related cytokine and angiogenesis were determinated. Our data showed that the concentrations of the triglyceride, total cholesterol and the low density lipoprotein cholesterol (LDL-C) and free fatty acid (FFA) showed a linear increase (P < 0.05) associated with increased backfat at late of gestation. ROS (P < 0.05) and MDA (P < 0.05) were significantly increased, and TAC were a significantly decreased (P < 0.05) as the backfat thickness increased. The mRNA expression of toll-like receptors (TLR) 2, TLR4, tumor necrosis factor (TNF) α, interleukin (IL) -1β, IL-6 and monocyte chemoattractant protein (MCP)-1 showed an increase associated with increased backfat at late of gestation. There is no difference in IL-8 and IL-10 mRNA expression among different backfat thickness sows. Placental vessel density showed an increase firstly and then decrease with the backfat thinness increasing of sows. Similarly, the mRNA levels of vascular endothelial growth factor (VEGF) were first rise and then drop. Our findings show that excessive backfat at the end of gestation was associated with higher the status of oxidative stress, greater expression of pro-inflammation cytokines, and decreased regulators of angiogenesis in the placenta.