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Expression and distribution of TTX‐sensitive sodium channel alpha subunits in the enteric nervous system
Author(s) -
Bartoo Aaron C.,
Sprunger Leslie K.,
Schneider David A.
Publication year - 2005
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.20541
Subject(s) - colocalization , calretinin , myenteric plexus , enteric nervous system , biology , ganglion , tetrodotoxin , calbindin , soma , sodium channel , dorsal root ganglion , microbiology and biotechnology , medicine , anatomy , sodium , endocrinology , immunohistochemistry , neuroscience , chemistry , dorsum , organic chemistry , immunology
The expression and distribution of TTX‐sensitive voltage‐gated sodium channel (VGSC) alpha subunits in the enteric nervous system (ENS) has not been described. Using RT‐PCR, expression of Na v 1.2, Na v 1.3, Na v 1.6, and Na v 1.7 mRNA was detected in small and large intestinal preparations from guinea pigs. Expression of Na v 1.1 mRNA as well as Na v 1.1‐like immunoreactivity (‐li) were not observed in any intestinal region investigated. Na v 1.2‐li was primarily observed within the soma of the majority of myenteric and submucosal neurons, although faint immunoreactivity was occasionally observed in ganglionic and internodal fibers. Na v 1.3‐li was observed in dendrites, soma, and axons in a small group of myenteric neurons, as well as in numerous myenteric internodal fibers; immunoreactivity was rarely observed in the submucosal plexus. Na v 1.6‐li was primarily observed in the initial axonal segment of colonic myenteric neurons. Na v 1.7‐li was observed in dorsal root ganglia neurons but not in the myenteric plexus of the small and large intestine. In the ileum, 37% of Na v 1.2‐li cell bodies colocalized with calbindin‐li while colocalization with calretinin‐li was rare. In contrast, 22% of Na v 1.3‐li cell bodies colocalized with calretinin‐li but colocalization with calbindin‐li was not observed. In the colon, both Na v 1.2‐li and Na v 1.3‐li cell bodies frequently colocalized with either calretinin‐li or calbindin‐li. Na v 1.2‐li cell bodies also colocalized with the majority of NeuN‐li cells in the small and large intestine. These data suggest that Na v 1.1 may not be highly expressed in the ENS, but that Na v 1.2, Na v 1.3, and Na v 1.6, and possibly Na v 1.7, have broadly important and distinct functions in the ENS. J. Comp. Neurol. 486:117–131, 2005. © 2005 Wiley‐Liss, Inc.