title: Cellular localization and distribution of neurokinin-1 receptors in the rat stomach.
abstract: In the stomach, the majority of substance P's effects are mediated by the activation of neurokinin-1 (NK1) receptors. The gastric cellular distribution of these receptors in Wistar and Sprague-Dawley rats was determined using immunocytochemistry. The localization of the NK1 receptors with respect to von Willebrand's factor, protein gene product 9.5, substance P, vasoactive intestinal peptide, and calcitonin gene-related peptide was also determined. Results show that NK1 receptor immunoreactivity was dependent on the duration of fixation. In corpus and antrum tissues that were fixed in 4% paraformaldehyde for 30 min, the presence of NK1 receptor immunoreactivity was demonstrated on nerve fibers throughout the stomach, on the surface and in the cytoplasm of myenteric cell bodies, on circular smooth muscle cells, and on vascular endothelial cells. This was observed in tissues from both rodent strains. Overnight fixation in the same fixative, however, demonstrated the presence of NK1 receptor immunoreactivity only on nerve fibers and cell bodies of the myenteric plexus, and on circular smooth muscle cells. In 30-min fixed tissues, the localization of NK1R immunoreactivity on vascular endothelial cells and nerve fibers was confirmed by co-localization with von Willebrand's factor and protein gene product 9.5 immunoreactivity, respectively. In both rodent strains, NK1 receptor immunoreactivity was co-localized with substance P immunoreactivity on nerve fibers of the longitudinal and circular muscle. In the Wistar rat, NK1 receptor immunoreactivity was co-localized with vasoactive intestinal peptide immunoreactivity or calcitonin gene-related peptide immunoreactivity throughout the stomach. However, in the Sprague-Dawley rat, NK1 receptor immunoreactivity was only co-localized with calcitonin gene-related peptide immunoreactivity in a minority of fibers of the circular muscle. The overall results of this study show that the antigenic epitopes of the NK1 receptor are sensitive to overfixation. When tissues were not overfixed, NK1 receptor immunoreactivity was distributed more extensively throughout the rat stomach than has been described previously. The results of this study provide the anatomical basis for many of the actions of substance P in the rat stomach.
authors.affiliation: Department of Physiology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3.
authors.forename: Linda
authors.initials: L
authors.lastname: Yip
authors.forename: Yin Nam
authors.initials: YN
authors.lastname: Kwok
authors.forename: Alison M J
authors.initials: AM
authors.lastname: Buchan
mesh_terms: D000818:Animals; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*; D013194:Staining and Labeling; D013270:Stomach / Q000166:cytology; D013373:Substance P / Q000378:metabolism; D016708:Synaptophysin / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000378:metabolism; D014018:Tissue Distribution; D016707:Tissue Fixation; D043222:Ubiquitin Thiolesterase; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D018040:Receptors, Neurokinin-1; D016708:Synaptophysin; D014841:von Willebrand Factor; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase