Gene Expression as a Sensitive Endpoint to Evaluate Cell Differentiation and Maturation of the Developing Central Nervous System in Primary Cultures of Rat Cerebellar Granule Cells (CGCs) Exposed to Pesticides

Abstract

The major advantage of primary neuronal cultures for developmental neurotoxicity testing (DNT) is their ability to replicate the crucial stages of neurodevelopment. In our studies using primary culture of cerebellar granule cells (CGCs) we have evaluated whether the gene expression relevant to the most critical developmental processes such as neuronal differentiation (NF-68 and NF-200) and functional maturation (NMDA and GABAA receptor), proliferation and differentiation of astrocytes (GFAP and S100ß) as well as presence of neural precursor cells (nestin and Sox10) could be used as an endpoint for in vitro DNT. The expression of these genes was assessed after exposure to various pesticides (paraquat parathion, dichlorvos, pentachlorophenol and cycloheximide) that could induce developmental neurotoxicity through different mechanisms. All studied pesticides significantly modified the expression of selected genes, related to neuronal and/or glial different stages of cell development and maturation. The most significant changes were observed after exposure to paraquat and parathion (down regulation of mRNA expression of NF-68 and NF-200, NMDA and GABAA). Similarly, dichlorvos affected mainly neurons (decreased mRNA expression of NF-68 and GABAA receptors) whereas cycloheximide had an effect on neurons and astrocytes as a significant decrease in the mRNA expression of both neurofilaments (NF-68 and NF-200) and astrocyte marker¿¿S100ß) was observed. Our results suggest that toxicity induced by pesticides that target multiple pathways of neurodevelopment can be identified by studying expression of genes that are involved in different stages of cell development and maturation and could be used as a sensitive endpoint for initial screening to identify the compounds with the potential to cause developmental neurotoxicity.