Effects Of NEFA And BHBA On Oxidative Stress Status Of Ketosis In Dairy Cows

Evaluating oxidative stress states is contributed to comprehend the pathogenesisof metabolic disorders in dairy cows. In this study, based on the experiment in vitroand in vivo, oxidative stress states was evaluated in ketotic and healthy cows, and itscorrelation with high concentrations of NEFA and/or BHBA to confirme that theoxidative stress is induced directly by the high concentration of NEFA and BHBA andcan cause “secondary injury” in the liver, and subsequently results in that the ketosisbecome more aggravated and complicated.To assess the oxidative stress states of ketotic and healthy cows during theperiparturient period, key indexes of oxidation and antioxidation nt key indexes inblood were determined. The results showed that the activities or contents ofantioxidation indicators （SOD, GSH-Px, CAT, TAC and VE） in ketotic cows weresignificantly lower than those of healthy cows, and have the negative correlation withNEFA and BHBA. Compared with healthy cows, oxidation indicators （H₂O₂, MDA,ROS, RNS, CYP2E1and iNOS） were significantly higher in ketotic cows andnegatively correlated with NEFA and BHBA. It indicated that periparturient dairycows develop severe oxidative stress which could be related to the increase of NEFAand BHBA concentration.Bovine hepatocyte was cultured by the modified two collagenase perfusion. Theeffects of different concentration of NEFA （0,0.4,0.8and1.6mmol/L） and BHBA（0,0.6,1.2,2.4mmol/L） on mRNA expression and enzymatic activity of Cu/Zn SOD,Mn SOD, GSH-Px, CAT, CYP2E1and iNOS in bovine hepatocyte were detected byreal-time PCR and ELISA. The results showed that different concentration of NEFAdecreased mRNA expression and activity of antioxidant enzymes, and promoted mRNA expression and activity of key enzymes of oxidative stress with adose-dependent. In addition, low concentration of BHBA could promote mRNA leveland activity of antioxidant key enzymes, while high concentration of BHBA inhibitedmRNA expression and activity. Different concentration of BHBA could increasemRNA expression and activity of key enzymes of oxidative stress, which was alsodose-dependent. With increased concentration of NEFA and BHBA, H₂O₂and MDAlevels were increased, and TAC concentration was decreased.As above-mentioned, it is concluded that kitotic dairy cows are subjected tosevere oxidative stress resulted from significant correlation with the increasedconcentration of blood NEFA and BHBA which could inhibit mRNA expression andactivity of antioxidant enzymes, and also promote mRNA expression and activity ofkey enzymes of oxidative stress.