AMPA, KA and NMDA receptors are expressed in the rat DRG neurones

The localization of AMPA receptor subunits (GluR1-4), a KA receptor subunit (GluR5) and NMDA receptor subunits (NR1 and NRgbs; the glutamate binding subunits of an NMDA receptor complex) was investigated using immunohistochemistry and in situ hybridization histochemistry in the rat dorsal root ganglion. Small neurones expressed GluR1-, GluR2/3-like immunoreactivities and GluR5, NR1, NRgbs mRNAs, while large neurones expressed GluR2/3-like immunoreactivity and NR1 and NRgbs mRNAs. These data suggest that the glutamatergic system plays an important role in the primary sensory afferent systems and that the composition of glutamate receptors differs according to the cell size.