Immunoelectron microscopic localization of NK-3 receptor in the rat spinal cord

The immunocytochemical localization of tachykinin NK-3 receptor (NK-3R) was studied in rat spinal cord using a mouse monoclonal antibody directed against the C-terminus peptide (434-465) of the human NK-3R. Light microscopic labeling prevailed in lamina II and lamina X. Under the electron microscope, the immunolabeling in lamina II involved mainly dendritic spines inside glomeruli, preterminal axons and axon terminals. This suggests that neurokinin B can modulate primary afferent, sensory information, both post- and pre-synaptically. These actions are likely to involve extrasynaptic diffusion of the peptide, since NK-3R immunoreactivity was not found in association with postjunctional differentiations.