No abstract

We report that basic fibroblast growth factor (bFGF) induces the release of glutamate in ES-derived neurons during early stages of differentiation. Changes of Ca²⁺concentration labeled by fluorescence intensity occurred in response to minimal concentrations of glutamate. The Ca²⁺concentration was changed more rapidly by bFGF than by glutamate during the early stages of differentiation of ES-derived neurons. High concentrations of the inhibitor MK801, a N-methyl-D-aspartate (NMDA) receptor antagonist applied before bFGF stimulation caused a dramatic decrease of fluorescence intensity in neurons derived from both hippocampal and ES cells. These results showed that bFGF induces glutamate release and an increase of [Ca²⁺] in neurons during early stages of differentiation, and that the increase of [Ca²⁺] can be inhibited by MK801. Therefore, we concluded that bFGF serves not only as a neurotrophin but also as a stimulator of excitability during the differentiation of ES cells into neurons.