TY - JOUR
T1 - 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
AU - Tseng, Leon F.
AU - Tsai, Judy H.H.
AU - Collins, Keith A.
AU - Portoghese, Philip S.
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 1995/4/24
Y1 - 1995/4/24
N2 - 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.
AB - 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.
KW - Antinociception
KW - Naltriben
KW - Tail-flick inhibition
KW - β-Endorphin
KW - δ-Opioid receptor
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U2 - 10.1016/0014-2999(95)00084-X
DO - 10.1016/0014-2999(95)00084-X
M3 - Article
C2 - 7493616
AN - SCOPUS:0028987763
SN - 0014-2999
VL - 277
SP - 251
EP - 256
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 2-3
ER -