Modulation of morphine antinociception by swim-stress in the mouse: involvement of supraspinal opioid delta-2 receptors
The present study evaluated the effect of a brief exposure of mice to cold-water swim-stress (CWSS) on the antinociceptive potency of i.c.v. given morphine. No significant antinociceptive response could be demonstrated in the warm-water tail-flick test, 10 min after a 30-sec exposure of mice to wate...
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Published in | The Journal of pharmacology and experimental therapeutics Vol. 267; no. 1; pp. 449 - 455 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Pharmacology and Experimental Therapeutics
01.10.1993
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Subjects | |
Online Access | Get full text |
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Summary: | The present study evaluated the effect of a brief exposure of mice to cold-water swim-stress (CWSS) on the antinociceptive
potency of i.c.v. given morphine. No significant antinociceptive response could be demonstrated in the warm-water tail-flick
test, 10 min after a 30-sec exposure of mice to water at 5 degrees C. However, the i.c.v. morphine dose-response curve in
mice exposed to CWSS was displaced significantly to the left when compared to that obtained in control (i.e., non-CWSS-exposed)
mice. Although coadministration of the delta antagonist, N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH 1 (ICI 174,864), with i.c.v. morphine
did not produce antagonism of the antinociceptive action of this mu opiate, the leftward displacement of the i.c.v. morphine
dose-response curve seen in CWSS-exposed mice was blocked in ICI 174,864-treated mice suggesting involvement of opioid delta
receptors in the modulatory effect. Pretreatment of mice with the delta-1 antagonist, [D-Ala2, Leu5, Cys6] enkephalin, did
not antagonize the antinociception of morphine and further did not antagonize the leftward displacement produced by exposure
to CWSS. Pretreatment of mice with the delta-2 antagonist, 5'-isothiocyanate, also did not antagonize the antinociceptive
effects of morphine but blocked the leftward displacement in the morphine dose-response curve associated with CWSS, suggesting
involvement of an opioid delta-2 receptor in this effect. Pretreatment of mice with the mu antagonist, beta-funaltrexamine,
produced a significant antagonism of the morphine antinociceptive effect as seen by a rightward displacement of the morphine
dose-effect curve. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0022-3565 1521-0103 |