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Effect of pilocarpine on the formalin-induced orofacial pain in rats

In this study, the effects of subcutaneous (SC) injection of pilocarpine (a cholinomimetic agent) and atropine (a muscarinic receptors antagonist) were investigated on a tonic model of orofacial pain in rats. The contribution of the endogenous analgesic opioid system was assessed using naloxone (an...

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Autores principales: Tamaddonfard, Esmaeal, Erfanparast, Amir, Khalilzadeh, Emad
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Urmia University Press 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4312802/
https://www.ncbi.nlm.nih.gov/pubmed/25653753
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author Tamaddonfard, Esmaeal
Erfanparast, Amir
Khalilzadeh, Emad
author_facet Tamaddonfard, Esmaeal
Erfanparast, Amir
Khalilzadeh, Emad
author_sort Tamaddonfard, Esmaeal
collection PubMed
description In this study, the effects of subcutaneous (SC) injection of pilocarpine (a cholinomimetic agent) and atropine (a muscarinic receptors antagonist) were investigated on a tonic model of orofacial pain in rats. The contribution of the endogenous analgesic opioid system was assessed using naloxone (an opioid receptors antagonist). Tonic orofacial pain was induced by SC injection of a diluted formalin solution (1%, 50 μL) in the right upper lip, and the time spent face rubbing was measured in five min blocks for 1 h. Formalin induced a biphasic (first phase: 0-5 min and second phase: 15-35 min) pain response. Pilocarpine significantly (P < 0.05) suppressed both phases of orofacial pain. Atropine did not have any effect and naloxone non-significantly increased the intensity of pain when used alone. In the pre-injection examinations, atropine prevented, but naloxone did not reverse the antinociceptive effect of pilocarpine. The results indicated that SC injection of formalin in the orofacial region induced a marked biphasic pain. Pilocarpine via muscarinic cholinergic receptors produced antinociceptive effect in the orofacial formalin-induced pain. The endogenous opioid analgesic system may not have a role in pilocarpine-induced antinociception.
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spelling pubmed-43128022015-02-04 Effect of pilocarpine on the formalin-induced orofacial pain in rats Tamaddonfard, Esmaeal Erfanparast, Amir Khalilzadeh, Emad Vet Res Forum Original Article In this study, the effects of subcutaneous (SC) injection of pilocarpine (a cholinomimetic agent) and atropine (a muscarinic receptors antagonist) were investigated on a tonic model of orofacial pain in rats. The contribution of the endogenous analgesic opioid system was assessed using naloxone (an opioid receptors antagonist). Tonic orofacial pain was induced by SC injection of a diluted formalin solution (1%, 50 μL) in the right upper lip, and the time spent face rubbing was measured in five min blocks for 1 h. Formalin induced a biphasic (first phase: 0-5 min and second phase: 15-35 min) pain response. Pilocarpine significantly (P < 0.05) suppressed both phases of orofacial pain. Atropine did not have any effect and naloxone non-significantly increased the intensity of pain when used alone. In the pre-injection examinations, atropine prevented, but naloxone did not reverse the antinociceptive effect of pilocarpine. The results indicated that SC injection of formalin in the orofacial region induced a marked biphasic pain. Pilocarpine via muscarinic cholinergic receptors produced antinociceptive effect in the orofacial formalin-induced pain. The endogenous opioid analgesic system may not have a role in pilocarpine-induced antinociception. Urmia University Press 2012 /pmc/articles/PMC4312802/ /pubmed/25653753 Text en This is an Open Access article distributed under the terms of the Creative Commons Attribution License, (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Article
Tamaddonfard, Esmaeal
Erfanparast, Amir
Khalilzadeh, Emad
Effect of pilocarpine on the formalin-induced orofacial pain in rats
title Effect of pilocarpine on the formalin-induced orofacial pain in rats
title_full Effect of pilocarpine on the formalin-induced orofacial pain in rats
title_fullStr Effect of pilocarpine on the formalin-induced orofacial pain in rats
title_full_unstemmed Effect of pilocarpine on the formalin-induced orofacial pain in rats
title_short Effect of pilocarpine on the formalin-induced orofacial pain in rats
title_sort effect of pilocarpine on the formalin-induced orofacial pain in rats
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4312802/
https://www.ncbi.nlm.nih.gov/pubmed/25653753
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