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Vagal and spinal afferent innervation of the rat esophagus: A combined retrograde tracing and immunocytochemical study with special emphasis on calcium‐binding proteins
Author(s) -
Dütsch Matthias,
Eichhorn Ulrike,
Wörl Jürgen,
Wank Michael,
Berthoud HansRudolf,
Neuhuber Winfried L.
Publication year - 1998
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/(sici)1096-9861(19980824)398:2<289::aid-cne9>3.0.co;2-x
Subject(s) - calretinin , retrograde tracing , nodose ganglion , calbindin , biology , anterograde tracing , immunocytochemistry , calcitonin gene related peptide , neuroscience , vagus nerve , ganglion , neurochemical , anatomy , calcium binding protein , neuropeptide , endocrinology , medicine , central nervous system , immunohistochemistry , calcium , receptor , immunology , stimulation , biochemistry
Vagal afferent neurons contain a variety of neurochemical markers and neuroactive substances, most of which are present also in dorsal root ganglion cells. To test for the suitability of the calcium‐binding protein calretinin as a specific marker for vagal afferent fibers in the periphery, immunocytochemistry for this protein was combined with retrograde tracing. Nerve fibers in the rat esophagus, as well as vagal and spinal sensory neurons innervating the esophagus, were investigated for co‐localization of calretinin with calbindin, calcitonin gene‐related peptide, and NADPH diaphorase. The results indicated that calretinin immunocytochemistry demonstrates neuronal structures known as vagal afferent from other studies, in particular intraganglionic laminar endings. A few enteric neurons whose distribution was unrelated to intraganglionic laminar endings also stained for calretinin. Strikingly, calretinin immunoreactivity was absent from spinal afferent neurons innervating the rat esophagus. In intraganglionic laminar endings and nodose ganglion cells calretinin was highly co‐localized with calbindin but not with calcitonin gene‐related peptide. On the other hand, calbindin was also found in spinal afferents to the esophagus where it was co‐localized with calcitonin gene‐related peptide. Vagal afferent neurons innervating the esophagus were never positive for NADPH diaphorase. Thus, calretinin appears to be a more specific marker for vagal afferent structures in the esophagus than calbindin, which is expressed by both vagal and spinal sensory neurons. Calretinin immunocytochemistry may be utilized as a valuable tool for investigations of subpopulations of vagal afferents in certain viscera. J. Comp. Neurol. 398:289–307, 1998. © 1998 Wiley‐Liss, Inc.