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Cellular localization of pan‐trk immunoreactivity and trk C mRNA in the enteric nervous system
Author(s) -
Sternini C.,
Su D.,
Arakawa J.,
de Giorgio R.,
Rickman D.W.,
Davis B.M.,
Albers K.M.,
Brecha N.C.
Publication year - 1996
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(19960513)368:4<597::aid-cne10>3.0.co;2-f
Subject(s) - trk receptor , tropomyosin receptor kinase a , tropomyosin receptor kinase b , enteric nervous system , tropomyosin receptor kinase c , neurotrophin , myenteric plexus , biology , medicine , endocrinology , microbiology and biotechnology , pathology , neurotrophic factors , receptor , immunohistochemistry , immunology , platelet derived growth factor receptor , biochemistry , growth factor
The members of the trk family of tyrosine receptor kinases, trk A , trk B , and trk C , are the functional receptors for neurotrophins, a family of related neurotrophic factors. In this study, we investigated 1) the distribution of neurotrophin receptors in the developing and adult rat digestive tract with a pan‐ trk antibody that recognizes all known trks and 2) the cellular localization of trk ‐encoding mRNAs in the adult gut with single‐stranded RNA probes specific for trk A , trk B , and trk C . In the developing myenteric plexus, trk immunoreactivity was present at embryonic day (ED) 14. Cells and fibers immunoreactive for trk could be visualized in the myenteric plexus at ED 16. At this age, dense staining was found in thick bundles of fibers in proximity to the myenteric plexus in the longitudinal muscle and in association with blood vessels in the mesentery. At ED 18, trk immunoreactivity was also seen in thin processes running from the myenteric plexus into the circular muscle, and in fibers and cells in intrapancreatic ganglia. By ED 20, immunoreactive staining was quite dense in both the myenteric and submucosal plexuses. At birth, virtually all enteric ganglia displayed strong trk immunoreactivity; the intensity of the staining at this age made it difficult to discern individual cells. During postnatal development, there was a decrease in cell body staining and an increase in the density of trk ‐containing fibers that became widely distributed to the gut wall and pancreas. The adult pattern of trk immunoreactivity was established between postnatal days 5 and 10. In adults, trk immunoreactivity was found in numerous enteric and intrapancreatic ganglion cells and in dense networks of fibers innervating all the layers of the gut, the pancreas, and vasculature. The trk C mRNA was expressed in adult enteric ganglion cells of both the myenteric and submucous plexus. By contrast, the trk A and trk B mRNAs could not be detected in enteric ganglia. All three trk mRNAs were expressed in dorsal root ganglia, which were used as positive controls. The density and wide distribution of trk immunoreactivity together with its persistence in adulthood support the concept that neurotrophins play a broad role in the digestive system from development through adult life, perhaps being involved in differentiation, phenotypic expression, and tissue maintenance. The presence of trk C mRNA in enteric neurons along with recent evidence that neurotrophin‐3 plays a role in the development of the enteric nervous system suggest that trk C and neurotrophin‐3 are a major neurotrophin system in the gastrointestinal tract. © 1996 Wiley‐Liss, Inc.