Localization of the neuropeptide manserin in rat dorsal root ganglia: Involvement in nociceptive function.

Manserin, a neuropeptide discovered in the rat brain, is distributed in the spiral ganglion of the inner ear and carotid body, suggesting it is also localized in another neuron cluster. In this study, we examined manserin's localization in the dorsal root ganglion (DRG) and spinal cord of adult Wistar rats using immunohistochemical analyses. The DRG consists of neurofilament (NF) 200-positive large cells and two types of small cells (calcitonin gene-related peptide (CGRP)-positive peptidergic neurons and isolectin B4 (IB4)-positive non-peptidergic neurons). Manserin was localized in some of the small cells. Fluorescence double immunostaining showed that manserin-positive cells corresponded to some of the CGRP-positive cells. The DRG comprises pseudo-unipolar cells that receive sensory information from the skin and viscera and project to each layer of the dorsal horn of the spinal cord. Manserin was localized in the CGRP-positive layer I and II outer, but not in the IB4-positive layer II inner. These results suggest manserin is localized in CGRP-positive cells in the DRG, projects to the dorsal horn of the spinal cord, and is secreted with other neuropeptides, such as CGRP, to participate in nociceptive function.