Rat DRG neurons express NR3 NMDA receptor subunits and excitatory glycine receptors

Abstract

NMDA receptors (NMDAR) located on the peripheral and central terminals of dorsal root ganglia (DRG) primary sensory neurons are involved in visceral nociception (1). We have recently shown that rat DRG neurons express predominantly the NR1, NR2B and NR2D subunits (2). A third family of NMDAR subunits, NR3A and NR3B, expressed at high levels during development, has recently been reported (3-5). Expression of NR3 subunits in combination with NR1 and NR2 subunits causes decreased NMDAR-mediated Ca2+ permeability and glutamate-mediated cytotoxicity (3-6). Furthermore, NMDARs containing NR3 subunits have been reported to act as excitatory glycine receptors (4). These subunits, in particular NR3B, are also expressed in adulthood in motor neurons and certain areas of the brain (4-7). However, nothing is known about their expression in sensory neurons.