The in?vitro effect of lipopolysaccharide on proliferation, inflammatory factors and antioxidant enzyme activity in bovine mammary epithelial cells

摘要

Abstract Lipopolysaccharide (LPS) was selected as a stimulus to investigate its effect on cell viability and oxidative stress in bovine mammary epithelial cells (BMEC) by detecting the cell relative growth rate (RGR), antioxidant indicators and inflammatory factors. This information was used to provide the theoretical basis for the establishment of a LPS-induced oxidative damage model. The experiment was divided into two parts. The first part used a two-factor experimental design to determine the appropriate incubation time of {LPS} by detecting the RGR. The third-passage {BMEC} were divided into 24 groups with six replicates in each group. The first factor was {LPS} concentration, which was 0 (control), 0.1, 1.0 and 10.0?μg/mL; the second factor was {LPS} incubation time (2, 4, 6, 8, 12 and 24?h). The optimum {LPS} incubation time was 6?h according to the results of the first part of the experiment. The second part of the experiment was conducted using a single-factor experimental design, and the third-passage cells were divided into four groups with six replicates in each group. The cells were incubated with culture medium containing different concentrations of {LPS} (0 [control], 0.1, 1.0 and 10.0?μg/mL) for 6?h to select the appropriate concentration of {LPS} to measure the antioxidant indicators and inflammatory factors. The results showed the {RGR} was significantly reduced as the concentration of {LPS} and the incubation time increased; the?interaction between concentration and incubation time was also significant. The cells treated with 0.1?μg/mL of {LPS} for 6?h had no significant difference in the activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) (P?>?0.05) compared with the cells in the control group. On the contrary, catalase (CAT) activity and malondialdehyde (MDA) content were markedly lower and higher, respectively, in the 0.1?μg/mL LPS-treated group for 6?h compared with the control group (P??0.05) difference between the 10.0 and 1.0?μg/mL LPS-treated groups. Compared with the control group, interleukin-1, interleukin-6 and nitric oxide concentrations and the activity of inducible nitric oxide synthase in the 0.1?μg/mL LPS-treated group significantly increased (P??0.05). All of observed indicators were higher in the 1.0 and 10.0?μg/mL LPS-treated groups (P??0.05) difference between the 1.0 and 10.0?μg/mL LPS-treated groups. The results indicated that a concentration of 1.0?μg/mL of {LPS} and an incubation time of 6?h were the optimum conditions necessary to induce oxidative stress in the {BMEC} and establish a model for oxidative damage.