Nuclear Localization of SP, CGRP, and NK 1 R in a Subpopulation of Dorsal Root Ganglia Subpopulation Cells in Rats

Signals generated by renal pelvic afferent nerves in response to stimulation are transmitted from peripheral processes of dorsal root ganglia neurons to their central terminals in the dorsal horn of the spinal cord to cause the release of neuropeptides, including SP and CGRP. All of the cellular activities of SP are considered to be mediated through interaction with NK₁R located on the cell surface. We have investigated the colocalization and subcellular distribution of NK₁R, SP, and CGRP in different subpopulations of neurons that innervate renal tissue. Our findings therefore provide the first evidence for the presence of NK₁R, SP, and CGRP in the nuclei of DGR neural cells. The physiological significance of this localization remains unknown. One possibility is that pelvic sensory neurons may regulate their responses to different stimuli by modulating the ratio of CGRP and SP release and/or nuclear NK₁R expression.