Spinal δ2-, but not δ1-, μ-, or κ-opioid receptors are involved in the tail-flick inhibition induced by β-endorphin from nucleus raphe obscurus in the pentobarbital-anesthetized rat

Leon F. Tseng, Judy H.H. Tsai, Keith A. Collins, Philip S. Portoghese

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The antinociception induced by β-endorphin given supraspinally has been previously demonstrated to be mediated by the release of [Met5]enkephalin acting on δ-opioid receptors in the spinal cord. The present study was designed to determine what type of opioid receptors in the spinal cord is involved in β-endorphin-induced antinociception in the rat. Antinociception was induced by β-endorphin (0.6 nmol) given into nucleus raphe obscurus and was assessed by the tail-flick test in pentobarbital-anesthesized rats. Naltriben (0.6-6.0 nmol), a selective δ2-opioid receptor antagonist, given intrathecally dose-dependently attenuated β-endorphin-induced inhibition of the tail-flick response. On the other hand, 7-benzylidene naltrexone (2.1-64.3 nmol), CTOP (d-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH2, 0.09-2.8 nmol), or nor-binaltorphimine (1.4-40.8 nmol), selective δ1-, μ-, and κ-opioid receptor antagonists, respectively, did not block β-endorphin-induced antinociception. The results of present study in rats are consistent with previous experiments in mice indicating that spinal δ2-, but not δ1-, μ- or κ-opioid receptors are involved in β-endorphin-induced inhibition of the tail-flick response.

Original languageEnglish (US)
Pages (from-to)251-256
Number of pages6
JournalEuropean Journal of Pharmacology
Volume277
Issue number2-3
DOIs
StatePublished - Apr 24 1995

Bibliographical note

Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.

Keywords

  • Antinociception
  • Naltriben
  • Tail-flick inhibition
  • β-Endorphin
  • δ-Opioid receptor

Fingerprint

Dive into the research topics of 'Spinal δ<sub>2-</sub>, but not δ<sub>1-</sub>, μ-, or κ-opioid receptors are involved in the tail-flick inhibition induced by β-endorphin from nucleus raphe obscurus in the pentobarbital-anesthetized rat'. Together they form a unique fingerprint.

Cite this