Inhibition by curcumin of TNF-α, IL-1β, IL-6, and NO in EMF-exposed N9 cells. N9 cells were pretreated with (+) or without (−) 20 μM curcumin for 1 h, and then stimulated with 200 ng/ml LPS or a 20-min EMF exposure for the indicated times. Levels for each sample were normalized compared to total protein in cell lysates. The concentrations of TNF-α (A), IL-1β (B) and IL-6 (C) in the medium were determined by ELISA after the cells were treated at the indicated times. (D) The amount of nitrite was determined by the Griess reaction. EMF exposure and LPS stimulation significantly increased the secretion of TNF-α, IL-1β and IL-6 and the production of NO in a time-dependent manner from 1 h to 12 h for N9 cells exposed to EMF. Curcumin neutralized the effect in EMF-exposed N9 cells. *P < 0.05, **P < 0.01 vs the sham-exposed control group; #
P < 0.05, ##
P < 0.01 vs the EMF-exposed group. con, control; Cur, curcumin; EMF, electromagnetic field; IL, interleukin; LPS, lipopolysaccharide; TNF-α, tumor necrosis factor α.