Evaluation of Neurotoxicity of Environmental Chemicals Using Neural Stem Cells and Neuroblastoma Cells

Abstract

Current risk assessment methods for environmental chemicals are based on adult physiology. However, recent reports have shown an increased incidence of neurodevelopmental disorders which may result from exposure to chemical in utero and during the early postnatal period. We previously showed that exposure of neonates to the environmental chemical p-nitrotoluene caused hyperactivity, accompanied by changes in the expression of the mesencephalic dopamine transporter gene. In this study, we have examined the effects of p-nitrotoluene on cultured neural stem cells isolated from the rat mesencephalon. At embryonic day 15, these cells stained positive with antibodies against nestin, microtubule-associated proteins, and glial fibrillary acidic proteins. The treatment of cultured neurospheres with p-nitrotoluene (1 ¼M; 72 h) facilitated differentiation with two distinct morphologies outside the sphere, being neural and glial lineages. Furthermore, we set up the bioassay for p-nitrotoluene neurotoxicity, based on neurite outgrowth using human neuroblastoma NB-1 cells. Addition of p-nitrotoluene (0.1∼1 μM) to the cultured NB-1 cells promoted the neurite outgrowth and IL-6 secretion in dose dependent manner.