Neurotrophins facilitate synthesis of choline acetyltransferase and tyrosine hydroxylase in cultured mouse neural stem cells independently of their neuronal differentiation.

Effects of three neurotrophins, i.e., nerve growth factor, brain-derived neurotrophic factor, and neurotrophin-3, on the expression of four neurotransmitter-synthesizing enzymes, i.e. choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), dopamine beta hydroxylase (DBH), and glutamate decarboxylase 65 were investigated in cultured mouse neural stem cells. All three neurotrophins enhanced the mRNA expression of ChAT, TH, or DBH of the cells caused to differentiate by the removal of fibroblast growth factor (FGF)-2 from the culture medium, and increased the protein and mRNA levels of ChAT and TH of even the undifferentiated proliferating neural stem cells due to the presence of FGF-2. These results demonstrate that neurotrophins stimulate the synthesis of ChAT and TH of the neural stem cells prior to neuronal differentiation, and suggest that neurotrophins may play roles in the commitment to neuronal cells and choice of specific neurotransmitter phenotypes in early stages of neurogenesis.