Effects of Co-Administration of Intrathecal Nociceptin/Orphanin FQ and Opioid Antagonists on Formalin-Induced Pain in Rats
Yonsei Medical Journal
; : 763-771, 2013.
Article
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| ID: wpr-211909
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ABSTRACT
PURPOSE:
Nociceptin/orphanin FQ (N/OFQ) as an endogeneous hexadecapeptide is known to exert antinociceptive effects spinally. The aims of this study were to demonstrate the antinociceptive effects of i.t. N/OFQ and to investigate the possible interaction between N/OFQ and endogenous opioid systems using selective opioid receptor antagonists in rat formalin tests. MATERIALS ANDMETHODS:
I.t. N/OFQ was injected in different doses (1-10 nmol) via a lumbar catheter prior to a 50 microL injection of 5% formalin into the right hindpaw of rats. Flinching responses were measured from 0-10 min (phase I, an initial acute state) and 11-60 min (phase II, a prolonged tonic state). To observe which opioid receptors are involved in the anti-nociceptive effect of i.t. N/OFQ in the rat-formalin tests, naltrindole (5-20 nmol), beta-funaltrexamine (1-10 nmol), and norbinaltorphimine (10 nmol), selective delta-, micro- and kappa-opioid receptor antagonists, respectively, were administered intrathecally 5 min after i.t. N/OFQ.RESULTS:
I.t. N/OFQ attenuated the formalin-induced flinching responses in a dose-dependent manner in both phases I and II. I.t. administration of naltrindole and beta-funaltrexamine dose-dependently reversed the N/OFQ-induced attenuation of flinching responses in both phases; however, norbinaltorphimine did not.CONCLUSION:
I.t. N/OFQ exerted an antinociceptive effect in both phases of the rat-formalin test through the nociceptin opioid peptide receptor. In addition, the results suggested that delta- and micro-opioid receptors, but not kappa-opioid receptors, are involved in the antinociceptive effects of N/OFQ in the spinal cord of rats.
Texte intégral:
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Indice:
WPRIM
Sujet Principal:
Mesure de la douleur
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Injections rachidiennes
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Rat Sprague-Dawley
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Récepteurs aux opioïdes
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Peptides opioïdes
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Formaldéhyde
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Analgésiques
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Naltrexone
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Antagonistes narcotiques
Limites du sujet:
Animals
langue:
En
Texte intégral:
Yonsei Medical Journal
Année:
2013
Type:
Article