Kappa, but not mu or delta, opioids attenuate responses to distention of afferent fibers innervating the rat colon. Gastroenterology 1996 Oct;111(4):968-80
Date
10/01/1996Pubmed ID
8831591DOI
10.1016/s0016-5085(96)70064-1Scopus ID
2-s2.0-0029835792 (requires institutional sign-in at Scopus site) 132 CitationsAbstract
BACKGROUND & AIMS: Discomfort and pain are the principal conscious sensations that arise from the viscera, and both are increased in frequency and intensity in patients with a functional bowel disorder. Visceral receptors, perhaps sensitized, may contribute to these altered sensations. The aim of this study was to evaluate the effects of opioid receptor-selective agonists on afferent fibers innervating the colon.
METHODS: Mechanosensitive pelvic nerve afferent fibers were recorded from the decentralized S1 dorsal root in anesthetized rats. The effects of opioid agonists, given intra-arterially, were studied based on the fiber's responses to noxious colorectal distention (CRD) (80 mm Hg, 30 seconds).
RESULTS: A total of 115 distention-sensitive fibers innervating the colon were studied, including 32 that were studied after colonic inflammation with 2.5% acetic acid. Neither mu-(morphine and fentanyl) nor delta- ([D-Pen2, D-Pen5]enkephalin- and SNC-80) opioid receptor agonists affected responses to CRD. In contrast, kappa- (U-50,488 and fedotozine) opioid receptor agonists dose-dependently attenuated responses to CRD. Acetic acid sensitized about half of the fibers studied, but neither the potency nor the efficacy of U-50, 488 or FDZ were changed after colonic inflammation.
CONCLUSIONS: These results suggest a role for peripheral kappa-opioid receptors in the modulation of visceral nociception.
Author List
Sengupta JN, Su X, Gebhart GFAuthor
Jyoti N. Sengupta PhD Professor in the Medicine department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-IsomerAfferent Pathways
Animals
Benzyl Compounds
Colon
Fentanyl
Male
Morphine
Propylamines
Pyrrolidines
Rats
Rats, Sprague-Dawley
Receptors, Opioid, delta
Receptors, Opioid, kappa
Receptors, Opioid, mu