The protective effect of selenium on the lipopolysaccharide-induced oxidative stress and depressed gene expression related to milk protein synthesis in bovine mammary epithelial cells

The objective of this study was to determine the effects of selenium (Se) on antioxidative function and the synthesis of milk protein in bovine mammary epithelial cells (BMECs). Two experiments were conducted using a single-factor completely randomized design study. In part I, BMECs were randomly divided into seven groups: control (without Se) and six Se treatments (10, 20, 50, 100, 150, and 200 nmol/L). In part II, based on the results of part I, we used lipopolysaccharide (LPS) as the induced stress source to analyze the protective effect of Se on LPS-induced oxidative damage and the influence on milk protein synthesis of BMECs. BMECs were randomly divided into eight groups: control (without Se and LPS), LPS treatment (only LPS), and six Se treatments with LPS (LS10 to LS200). Treatment of BMECs with Se was found to significantly improve cell proliferation and antioxidant function. LPS could induce oxidative damage which significantly inhibited cell proliferation and antioxidant function in BMECs. Se had a protective effect on the oxidative damage of BMECs induced by LPS. Additionally, our results indicated that LPS damage downregulated the gene expression of milk protein synthesis. Se effectively relieved the inhibition due to LPS-induced oxidative damage on the synthesis of milk protein, and Se concentrations of 50 to 200 nmol/L showed the best effect. In conclusion, Se at concentrations of 50 to 100 nmol/L is better for antioxidant function but had no effect on milk protein synthesis in healthy BMECs. Se ameliorated the damage caused by LPS-induced by improving levels of antioxidant markers and upregulating milk protein synthesis and the expression of genes associated with milk protein in BMECs.