Proanthocyanidins Protect against β-Hydroxybutyrate-Induced Oxidative Damage in Bovine Endometrial Cells

Metabolic diseases, such as ketosis, are closely associated with decreased reproductive performance (such as delayed estrus and decreased pregnancy rate) in dairy cows. The change of beta-hydroxybutyrate (BHBA) concentration in dairy cattle is an important mechanism leading to ketosis, and its blood concentration in ketotic cows is always significantly higher than in nonketotic cows. Many studies indicated that BHBA can induce oxidative damage in liver and other organs. Proanthocyanidins (PCs) have gained substantial attention in the last decade as strong antioxidative substances. This study aimed to demonstrate a protective effect of PCs against BHBA-induced oxidative stress damage in bovine endometrial (BEND) cells by activating the nuclear erythroid2-related factor2 (Nrf2) signaling pathway. Our research show that PCs could significantly increase activities of catalase (CAT) and glutathione peroxidase (GSH-PX), glutathione (GSH) content, and antioxidant capacity (T-AOC), while significantly decreasing malondialdehyde (MDA) content in BEND cells. Both mRNA and protein expression levels of Nrf2 were significantly increased in BEND cells, and glutamate-cysteine ligase catalytic subunit (GCLC), heme oxygenase 1 (HO-1), manganese superoxide dismutase (Mn-SOD), and NAD(P)H quinone dehydrogenase 1 (NQO-1) were also significantly increased. These results indicate that PCs can antagonize BHBA-induced oxidative damage by activating the Nrf2 signaling pathway to exert an antioxidant effect.