Glutamate induces a depolarization of adult rat dorsal root ganglion neurons that is mediated predominantly by NMDA receptors.

The effects of glutamate, glutamate receptor agonists and substances that affect glutamate responses were studied, using the whole-cell patch-clamp technique, on neurons isolated from adult rat dorsal root ganglia. In current-clamp, glutamate (100 microM) or the excitatory amino acid receptor agonist N-methyl-D-aspartate (NMDA; 10 or 100 microM) induced membrane depolarization. Under voltage-clamp, these compounds induced an inward current that was voltage-dependent in the presence of Mg2+. The NMDA-induced current was inhibited by the NMDA receptor antagonist D,L-2-amino-5-phosphono-valerate (APV; 100 microM), and potentiated by 100 nM glycine. Few neurons responded to the receptor agonists kainate (100 microM), or quisqualate (1-10 microM). These observations suggest that glutamate-induced depolarization of primary sensory neurons is mediated predominantly by NMDA receptors.