OBJECTIVE To investigate the effect of curcumin on proliferation of neural stem cells (NSCs) of rats and the mechanism. METHODS NSCs derived from the forebrain of rat E15 embryos were cultured in vitro and identified by neuroepithelial stem cell protein ( nestin and SOX2) staining. NSCs were treated with curcumin 0.1, 0.5, 2.5, 12.5 and 62.5 μmol.L-1 for 24 h, respectively. The cyto-toxicity was estimated by measuring the release of lactate dehydrogenase(LDH). Cell viability and prolif-eration were analyzed respectively by MTT and BrdU assay. The mRNA expression levels of glucocorti-coid receptor (GR), Stat3, Notch1 and p21 were detected by qRT-PCR. The protein expression levels of total GR, Stat3 and phosphorylated Stat3 were measured by Western blotting. RESULTS The primary neural stem cells were identified as NSCs. Curcumin 12.5 and 62.5 μmol.L-1 had cell cytotoxicity( P<0.05). Cell viability assay indicated that curcumin 0.5 and 2.5 μmol.L-1 enhanced NSCs viability( P <0.05), but in 62.5 μmol.L-1 group the cell cytotoxicity was inhibited(P<0.05). Curcumin 0.1, 0.5 and 2.5 μmol.L-1 increased NSCs proliferation ( P < 0. 05), whereas 12. 5 and 62. 5 μmol.L-1 caused a decrease in NSCs proliferation(P<0.05). The mRNA expression level of GR in 0.5 μmol.L-1 group was significantly reduced( P<0.05). Western blotting analysis revealed that the protein expression of GR, Stat3 and p-Stat3 was inhibited by curcumin in 0.5 μmol.L-1 group(P<0.05). CONCLUSION Curcumin stimulates NSCs proliferation, possibly by inhibiting GR mRNA and related protein expression.