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J Neurophysiol. 2014 Sep 15;112(6):1392-408. doi: 10.1152/jn.00560.2013. Epub 2014 May 28.

Distinct subclassification of DRG neurons innervating the distal colon and glans penis/distal urethra based on the electrophysiological current signature.

Author information

1
Department of Anesthesiology, Department of Anatomical Sciences and Neurobiology, and Kentucky Spinal Cord Injury Research Center, University of Louisville College of Medicine, Louisville, Kentucky; Department of Physiological Sciences, University of Florida College of Veterinary Medicine and McKnight Brain Institute, Gainesville, Florida kkrau001@louisville.edu.
2
Department of Anatomical Sciences and Neurobiology, Department of Neurological Surgery, Kentucky Spinal Cord Injury Research Center, University of Louisville College of Medicine, Louisville, Kentucky;
3
Department of Oral and Maxillofacial Surgery, Division of Neuroscience, J. Hillis Miller Health Center, University of Florida College of Dentistry and McKnight Brain Institute, Gainesville, Florida; and.
4
Department of Physiological Sciences, University of Florida College of Veterinary Medicine and McKnight Brain Institute, Gainesville, Florida.

Abstract

Spinal sensory neurons innervating visceral and mucocutaneous tissues have unique microanatomic distribution, peripheral modality, and physiological, pharmacological, and biophysical characteristics compared with those neurons that innervate muscle and cutaneous tissues. In previous patch-clamp electrophysiological studies, we have demonstrated that small- and medium-diameter dorsal root ganglion (DRG) neurons can be subclassified on the basis of their patterns of voltage-activated currents (VAC). These VAC-based subclasses were highly consistent in their action potential characteristics, responses to algesic compounds, immunocytochemical expression patterns, and responses to thermal stimuli. For this study, we examined the VAC of neurons retrogradely traced from the distal colon and the glans penis/distal urethra in the adult male rat. The afferent population from the distal colon contained at least two previously characterized cell types observed in somatic tissues (types 5 and 8), as well as four novel cell types (types 15, 16, 17, and 18). In the glans penis/distal urethra, two previously described cell types (types 6 and 8) and three novel cell types (types 7, 14, and 15) were identified. Other characteristics, including action potential profiles, responses to algesic compounds (acetylcholine, capsaicin, ATP, and pH 5.0 solution), and neurochemistry (expression of substance P, CGRP, neurofilament, TRPV1, TRPV2, and isolectin B4 binding) were consistent for each VAC-defined subgroup. With identification of distinct DRG cell types that innervate the distal colon and glans penis/distal urethra, future in vitro studies related to the gastrointestinal and urogenital sensory function in normal as well as abnormal/pathological conditions may be benefitted.

KEYWORDS:

classification; dorsal root ganglion; nociception; sensory neuron; viscera

PMID:
24872531
PMCID:
PMC4137247
DOI:
10.1152/jn.00560.2013
[Indexed for MEDLINE]
Free PMC Article

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