Gene expression profiling reveals distinct cocaine-responsive genes in human fetal CNS cell types

Objectives: Prenatal exposure to cocaine causes cytoarchitectural alterations in the developing neocortex. Previously, we reported that cocaine inhibits neural progenitor cell proliferation through oxidative endoplasmic reticulum stress and consequent down-regulation of cyclin A, whereas cyclin A expression was increased in astrocytes. In the present study, cell type-specific responses to cocaine were further explored.

Methods: Gene expression profiles were examined in five types of cells obtained from the human fetal cerebral cortex at 20 weeks gestation. Cells were treated with 100 µM cocaine in vitro for 24 hr, followed by gene expression analysis using a human neural/stem cell/drug abuse-focused cDNA array, with verification by quantitative real-time RT-PCR.

Results: Cocaine influenced transcription of distinct categories of genes in a cell type-specific manner. Cocaine down-regulated cytoskeleton-related genes including ezrin, γ2 actin, α3d tubulin and α8 tubulin in neural and/or A2B5+ progenitor cells. In contrast, cocaine modulated immune and cell death-related genes in microglia and astrocytes. In microglia, cocaine up-regulated the immunoregulatory and pro-apoptotic genes IL-1β and BAX. In astrocytes, cocaine down-regulated the immune response gene glucocorticoid receptor and up-regulated the anti-apoptotic genes 14-3-3 ε and HVEM. Therefore, cell types comprising the developing neocortex show differential responses to cocaine.

Conclusions: These data suggest that cocaine causes cytoskeletal abnormalities leading to disturbances in neural differentiation and migration in progenitor cells, while altering immune and apoptotic responses in glia. Understanding the mechanisms of cocaine's effects on human CNS cells may help in the development of therapeutic strategies to prevent or ameliorate cocaine-induced impairments in fetal brain development.