Selenium (Se) and Selenoprotein W (SelW) plays a pivotal role in the brain development, function, and degeneration and that SelW expression in the brain may be affected by Se. However, the mechanism which Se regulates the SelW gene expression in neurons remains to be unclear. To investigate the effects of the SelW gene expression and mRNA stability induced by Se, primary cultured chicken embryos neurons derived from 8-day-old chick embryo cerebral hemispheres were treated with 10(-9)-10(-5) mol/l Se as selenite for 3, 6, 12, 24 or 48 h, respectively. The morphology and viability of Neurons was detected. The SelW mRNA expression level and mRNA half-life was examined in Se-treated neurons. The relative low concentrations of Se enhanced the neurite outgrowth, increased the SelW mRNA levels and elevated the mRNA half-life of chick embryo neurons. In contrast, the high concentrations of Se presented neurotoxic to neurons, decreased the SelW mRNA levels and reduced the mRNA half-life of neuronal cells. These results suggest that the alteration of post-transcriptional stabilization of SelW mRNA is an important mechanism of Se-induced the elevation or reduction of the SelW expression level in chick embryo neurons.