Substance P (NK1) receptor in relation to substance P innervation in rat duodenum after irradiation.
It has previously been shown that high dose of irradiation to the rat abdomen leads to an increased level of substance P (SP) in the duodenum. In the present study the pattern of distribution of NK1 receptors (NK1-R) in rat duodenum after irradiation (5-30 Gy), was examined at the same time-point (7 days) after irradiation, comparisons being made with the distribution of SP-innervation. Immunohistochemical methods were used. In controls, NK1-R-like immunoreactivity (-LI) was detected in epithelial cells, in cells in the region of the intestinal cells of Cajal within the deep muscular plexus (ICC-DMP), in neuronal cells in the myenteric plexus, and variably in granulocytes in the mucosa. Irradiation with 5-10 Gy did not lead to obvious changes in the pattern of NK1-R-LI. After irradiation with the highest doses (25-30 Gy), the mucosa was often gravely damaged, displaying granulation tissue. No epithelial NK1-R-LI was detected in this tissue, but was present in less affected mucosa after these doses. In the region of the ICC-DMP, in the myenteric plexus, and in granulocytes, NK1-R-LI was detected also after high dose irradiation. However, the degree of NK1-R-LI in the region of the ICC-DMP was somewhat lower than seen in controls and after low doses. SP-immunoreactive nerve fibers were present in the regions where NK1-R-LI was detected. These findings support a suggestion that an increased level of SP after irradiation may contribute to the dose-dependent gastrointestinal adverse effects that occur after radiotherapy.
Department of Integrative Medical Biology, Anatomy, Umeå University, SE-901 87, Umeå, Sweden. ulf.hockerfelt@anatomy.umu.se
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D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004386:Duodenum / Q000378:metabolism* / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D005720:Gamma Rays; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D008407:Mast Cells / Q000473:pathology / Q000528:radiation effects; D008856:Microscopy, Fluorescence; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D009197:Myenteric Plexus / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D018040:Receptors, Neurokinin-1 / Q000276:immunology / Q000378:metabolism*; D013368:Submucous Plexus / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D013373:Substance P / Q000276:immunology / Q000378:metabolism*
D018040:Receptors, Neurokinin-1; D013373:Substance P