Neurite outgrowth of neural cells serves as an index of the neurotoxicity of environmental chemicals. We previously demonstrated the in vivo neurotoxicity of p-nitrotoluene: exposure of rat pups to p-nitrotoluene causes juvenile hyperactivity. To further explore the neurotoxicity of p-nitrotoluene in vitro, in this study we examined the in vitro neurotoxicity of p-nitrotoluene using cultured human neuroblastoma NB-1 cells. Addition of p-nitrotoluene (0 ~ 1 µM) to NB-1 cells significantly promoted neurite outgrowth (P < 0.05); a dose of 0.5 µM p-nitrotoluene was as effective as 1 µM, whereas 0.1 µM p-nitrotoluene failed to promote outgrowth. The effects of the chemical were stereoisomer-specific. During p-nitrotoluene-induced neurite outgrowth, interleukin (IL)-6 was secreted into the culture medium in a dose-dependent manner and increased 1.7-fold following incubation for 48 h with 1 µM p-nitrotoluene. Thus, we show for the first time that p-nitrotoluene concomitantly promotes neurite outgrowth and IL-6 secretion in human neuroblastoma NB-1 cells.
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