Metabolites and hormones manipulated effect on mRNA abundance of antioxidant genes related to Nrf2 in mammary tissue of dairy cows

Mammary immune suppression has been observed in high yielding dairy cows due to metabolites and endocrine changing after parturition. Twenty four Holstein dairy cows at the late stage of lactation were used to study the effects of long term (48 h) manipulating metabolites and hormones on mammary antioxidant genes that encode by nuclear factor E2-related factor 2 (Nrf2). Treatments include 48 h intravenous infusion of insulin (HypoG, n=5), insulin and glucose (hyperinsulinemic euglycemic) (EuG, n=6), BHB (HyperB, n= 5), and 0.9 % NaCl (Control, n=8). Mammary tissue samples were taken from two rare quarters one week before and 48 h after the start of infusions. Following total RNA extraction, mRNA abundance of housekeeping and candidate genes related to Nrf2 measured by qPCR method. Hyperinsulinemic euglycemic down-regulated mRNA abundance of catalase (CAT),heme oxygenase 2 (HMOX2), microsomal glutathione S-transferase 3 (MGST3), NAD (P) H dehydrogenase, quinone 1 (NQO1),superoxide dismutase 1 (SOD1) (P<0.05), compared to pre-infusion in EuG group. Hyperinsulinemic euglycemic down-regulated GPX3 mRNA abundance in EuG group compared to HyperB group (P<0.05). Therefore, increased susceptibility and disease in mammary gland may be related to reduction in the mRNA abundance of antioxidant genes during metabolites and hormones changing.