Transcriptome of tributyltin-induced apoptosis of the cultured rat mesencephalic neural stem cells

Exposure to environmental neurotoxic chemicals both in utero and during the early postnatal period can cause neurodevelopmental disorders. To evaluate the disruption of neurodevelopmental programming, we previously established an in vitro neurosphere assay system, using rat mesencephalic neural stem cells (mNSC). Here, we examined the developmental neurotoxicity of tributyltin (TBT) in an in vitro neurosphere assay. A neurosphere was driven from rat E16 mesencephalon and seeded in a poly-l-ornithine/laminin-coated plate. Exposure to TBT increased the number of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL)-positive cells in time-dependent and dose-dependent manner: it was significantly detectable with treatment of 100 pM TBT for 90 min, or of 1 μM TBT for 30 min. Disruption of mitochondrial membrane potential and activation of caspase-3/7 were concomitantly observed. Furthermore, DNA microarray analyses using Affymetrix GeneChip revealed that as early as 0.5 h after exposure to the metal (1 μM), the expression levels of 71 genes were increased by more than 2-fold, whereas those of 8 genes were decreased by 2-fold or less: it was notably altered in expression of Ca2+-mobilizing-related genes, and retinoic-acid signal-related genes, as well as bifunctional apoptosis-related genes. The levels of gene expression of Wnt family were also significantly changed. Thus, we established transcriptome of TBT-induced apoptosis of mNSC. This would help to evaluate developmental neurotoxicity of TBT in vivo, contributing to the risk assessment methods based on infant physiology.

► Exposure of rat neurosphere to tributyltin (TBT) induced apoptosis.
► It was mediated through the mitochondrial caspase-mediated pathway.
► DNA array analyses revealed the involvement of other signaling pathways.
► The development of dopamine neurons by Wnt family could be disrupted by TBT.
► Transcriptome of TBT-induced apoptosis would evaluate neurodevelopmental toxicity.