Effect of intramammary lipopolysaccharide challenge on mRNA abundance of antioxidant genes associated with nuclear erythroid 2-related factor 2 in mammary tissue of dairy cows during change of metabolites and hormones

To study the reaction of udder mRNA abundance of genes related to nuclear erythroid 2-related factor 2 (Nrf2) to an intramammary lipopolysaccharide (LPS) challenge with changes in blood insulin and metabolites levels, 24 dairy cows were used. Treatments included insulin infusion (HypoG, n=5), insulin and glucose (EuG, n=6), β-hydroxybutyrate (HyperB, n= 5), and saline (Control, n=8) for 56 h. At 48 h of infusions, two quarters were treated with 200µg LPS, and two control quarters were treated with physiological serum. Mammary tissue biopsies were obtained before and after the LPS challenge. The mRNA abundance of the genes was measured by the qPCR approach. In the LPS quarters, the mRNA abundance of MT1A, MT2A, and MT1E increased in all treatments. The mRNA abundance of GPX3 increased in HyperB and Control. The mRNA abundance of MGST3 and SOD1 decreased in all groups lacking EuG. Decreased mRNA abundance of NQO1 observed in HypoG. In the control quarters, the mRNA abundance of MT1A and MT2A was raised in all groups. Similarly, MT1E is up-regulated in all groups except for the HypoG. The increase of mRNA abundance of GPX3 was observed in the Control and EuG groups, and UGT1A1 in EuG. LPS decreased the mRNA abundance of MGT3, NQO1, and SOD1 in HypoG. In conclusion, LPS influenced the mRNA quantity of the investigated genes in both quarters, which indicate local and systemic reactions to endotoxin. Applying appropriate management strategies will reduce oxidative stress and susceptibility to diseases and will lead to better welfare and performance of the animal.