Co-localization of AMPA receptor subunits in the nucleus of the solitary tract in the rat

AMPA-type glutamate receptors in the caudal portions of nucleus of the solitary tract (NTS) are critical for responses to excitatory afferents from the viscera, including baroreceptors. Using immunocytochemistry combined with electron microscopy, the cellular distributions of different AMPA receptor subunits in the caudal NTS were found to be distinct. GluR2/3 was found at pre- and postsynaptic sites, and in astrocytic glia; while GluR1 was found primarily in small dendrites and spines. In dual-labeling studies, GluR1 and GluR2 were co-localized in large dendrites, but GluR1 was more often found alone in dendritic spines. Therefore, single neurons in the NTS contain both subunits, but there is differential trafficking of GluR1 to potential sites for synaptic plasticity.