Effects of lysophosphatidic acid (LPA), an extracellular phospholipid signal, on the proliferation of rat embryonic neural stem cells (NSCs) and their differentiation into microtubule-associated protein 2 (MAP2)-positive and choline acetyltransferase (ChAT)-positive, i.e. cholinergic-committed neurons, were observed in vitro by [(3)H]-thymidine incorporation, immunocytochemistry, Western blot and other techniques. The results showed that: (1) Lower concentrations of LPA (0.01~1.0 mumol/L) dose-dependently enhanced the uptake of [(3)H]-thymidine by NSCs cultured in specific serum-free medium, indicating a significant promotive action of LPA on the proliferation of NSCs. (2) After fetal bovine serum which induces and commences the differentiation of NSCs, was used in the medium, the lower concentrations of LPA increased the percentages of both MAP2- and ChAT-immunoreactive neurons, with a peak at 0.1 mumol/L LPA in two cases. (3) The promotive effects of LPA on the differentiation of MAP2- and ChAT-positive neurons were also supported by the up-regulation of the expressions of both MAP2 and ChAT proteins detected by Western blot. (4) At the early phase of differentiation of NSCs, the cell migration and neurite extension were enhanced significantly by lower dosages of LPA under phase-contrast microscope. These results suggest that LPA within certain lower range of concentrations promotes the proliferation of NSCs and their differentiation into unspecific MAP2-positive and specific cholinergic-committed neurons, and also strengthens the migration and neurite extension of the newly-generated neuronal (and also glial as reported elsewhere) progenitors.