Faculty Collaboration Database

Differential effects of mu-, delta-, and kappa-opioid receptor agonists on mechanosensitive gastric vagal afferent fibers in the rat. J Neurophysiol 2000 Apr;83(4):2209-16

Date

04/12/2000

Pubmed ID

10758129

DOI

10.1152/jn.2000.83.4.2209

Scopus ID

2-s2.0-0034111874 (requires institutional sign-in at Scopus site)   60 Citations

Abstract

Single-fiber recordings were made from the decentralized right cervical vagus nerve (hyponodosal) of the rat. A total of 56 afferent fibers that responded to gastric distension (GD) were studied: 6 fibers were stimulated by phasic balloon GD, 50 by fluid GD. All fibers gave increasing responses to increasing pressures of GD (5-60 mmHg). The effects of mu-opioid (morphine), delta-opioid (SNC80), and kappa-opioid (EMD61,753, U62,066) receptor agonists were tested on responses of afferent fibers to GD. Morphine, administered systemically over a broad dose range (10 microg to 31 mg/kg, cumulative), had no effect on either resting activity or responses of vagal afferent fibers to GD. Similarly, the delta-opioid receptor agonist SNC80 (0.05-3.2 mg/kg) did not affect resting activity or responses to GD. In contrast, cumulative intra-arterial doses of the kappa-opioid receptor agonist EMD61,753 or U62,066 dose dependently attenuated afferent fiber responses to GD. Doses producing inhibition to 50% of the control response to GD of EMD61,753 (8.0 mg/kg) and U62,066 (8.8 mg/kg) did not differ. The effect of U62,066 was moderately attenuated by a nonselective dose (4 mg/kg) of naloxone hydrochloride; the kappa-opioid receptor-selective antagonist nor-BNI (20 mg/kg) was ineffective. These results demonstrate that kappa-, but not mu- or delta-opioid receptor agonists modulate visceral sensation conveyed by vagal afferent fibers innervating the stomach. Given that kappa-opioid receptor agonists effects were only modestly antagonized by naloxone and not at all by nor-BNI, the results point to a novel site of action.

Author List

Ozaki N, Sengupta JN, Gebhart GF

MESH terms used to index this publication - Major topics in bold

Acetamides
Analgesics
Analgesics, Opioid
Animals
Benzamides
Catheterization
Electric Stimulation
Male
Mechanoreceptors
Morphine
Naloxone
Narcotic Antagonists
Nerve Fibers
Neurons, Afferent
Pain
Piperazines
Pyrrolidines
Rats
Rats, Sprague-Dawley
Receptors, Opioid
Receptors, Opioid, delta
Receptors, Opioid, kappa
Receptors, Opioid, mu
Stomach
Vagus Nerve