Axotomized rat facial nucleus-derived microglia were isolated and cultured in vitro. The microglia were sub-cultured non-invasively by a specific polymer-grafted dish. The microglia showed a specific uptake of 14C-Glu by a glutamate transporter, GLT-1. The microglia expressed glutamine synthetase (GS) protein and showed GS activity. The microglia were suggested to change the uptaken 13C-Glu to 13C-Gln by their GS.