Glutamate receptor-mediated calcium surges in neurons derived from P19 cells.

Retinoic acid-treated murine P19 embryonal carcinoma cells differentiate into cells with neuronal morphology that display typical neuronal markers. In this study, the presence of glutamate receptors linked to Ca(2+)-signaling mechanisms on these neurons was demonstrated by testing the effects of glutamate agonists and antagonists on the intracellular calcium ion concentration ([Ca2+]i). Glutamate (1 mM) induced either sustained or transient increases in [Ca2+]i. The sustained glutamate-induced increase in [Ca2+]i was mimicked by NMDA (40 microM). The NMDA-triggered [Ca2+]i response was abolished by incubating the cells in Ca(2+)-free medium or by pretreating them with Mg2+ (2 mM) or MK-801 (0.1 microM). These responses were unaffected by the non-NMDA antagonist CNQX (10 microM), but they required glycine (3-30 microM). Kainate (40 microM) and AMPA (40 microM) did not affect [Ca2+]i. Without external Ca2+, glutamate triggered transient, sometimes oscillating, increases in [Ca2+]i. These responses were mimicked by the metabotropic agonist trans-(1S, 3R)-1-amino-1,3-cyclopentanedicarboxylic acid (300 microM). These results suggest that neurons derived from P19 embryonal carcinoma cells have NMDA and metabotropic, but not AMPA/kainate receptors, which are linked to Ca(2+)-signaling mechanisms. These cells could provide a consistent and reproducible model with which to study neuronal differentiation, neurotoxicity, and glutamate receptor-signaling mechanisms.