Figure 4. An ERK inhibitor improves NOX4 expression, inflammation, oxidative stress and apoptotic level of DRG neurons cultured in PA-added medium in vitro. PA was applied to simulate a high-fat environment and U0126 to inhibit ERK. (A) The expression of p-ERK, ERK, and NOX4 in DRG neurons were detected by western blot. (B–D) The supernatant of cultured cells was collected and the secretion of IL-1β, IL-6, and TNF-α was determined by ELISA. (E) The ROS content was detected by oxidant-sensitive fluorescence probe DHE. (F, G) The expression of cleaved caspase3, bcl-2 and bax in DRG neurons were detected by western blot. (H) Cell apoptosis level was detected by TUNEL method. N = 5 per group, **P < 0.01 vs. con group, #P < 0.05 vs. saline group, ##P < 0.01 vs. saline group. U0126, ERK inhibitor; ERK, extracellular-regulated kinase; NOX4, NAD(P)H oxidase 4; PA, palmitic acid; DRG, dorsal root ganglia; IL-1β, interleukin-1 beta; IL-6, interleukin-6; TNF-α, tumor necrosis factor alpha; ELISA, enzyme-linked immunosorbent assay; DHE, dihydroethidium; ROS, reactive oxygen species.