Dichotomizing axons in spinal and vagal afferents of the mouse stomach.
Visceral sensory input is typically poorly localized. We hypothesized that gastric sensory neurons frequently dichotomize, innervating more than one anatomically distinct region and contributing to the poor spatial discrimination.


METHODS
The neurochemical phenotype and projections of gastro-duodenal sensory neurons were determined in adult mice. Choleratoxin B (CTB) coupled to different fluorophors was injected into fundus, corpus, antrum, and/or distal duodenum. Immunoreactivity for TRPV1, neurofilament (N52), calcitonin gene-related peptide (CGRP), presence of isolectin B4 (IB4) and labeling for retrograde labels was determined.


RESULTS
Depending on the distance between injection sites, staining for two retrograde tracers was seen in 6-48% of neurons. Most dorsal root ganglion (DRG) neurons showed immunoreactivity for TRPV1 and CGRP. In contrast, about half of the gastric nodose ganglion (NG) neurons had TRPV1 immunoreactivity or showed IB4 labeling with only 10% CGRP-positive neurons. N52 immunoreactivity was present in one-fourth of gastroduodenal DRG and NG neurons.


CONCLUSIONS
Visceral sensory neurons have neurochemical properties and may project to more than one anatomically distinct area. Neurons with such dichotomizing axons may contribute to the poor ability to localize or discriminate visceral stimuli.
Zhong
Fang
F
Division of Gastroenterology, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Christianson
Julie A
JA
Davis
Brian M
BM
Bielefeldt
Klaus
K
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001369:Axons; D015740:Calcitonin Gene-Related Peptide / Q000276:immunology / Q000378:metabolism; D004195:Disease Models, Animal; D005727:Ganglia, Spinal / Q000166:cytology* / Q000378:metabolism; D006023:Glycoproteins / Q000276:immunology / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016900:Neurofilament Proteins / Q000276:immunology / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology* / Q000378:metabolism; D010784:Photomicrography; D013270:Stomach / Q000294:innervation*; D050916:TRPV Cation Channels / Q000276:immunology / Q000378:metabolism; D014630:Vagus Nerve / Q000166:cytology* / Q000378:metabolism; D014781:Viscera / Q000294:innervation
D000906:Antibodies; D006023:Glycoproteins; D016900:Neurofilament Proteins; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; C473590:isolectin B4-binding glycoprotein, mouse; D015740:Calcitonin Gene-Related Peptide