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The role of central opioid and CB1 cannabinoid receptors in the antinociceptive effect of curcumin on the formalin-induced muscle pain in rats
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Nabat Naqshbandi *   , Esmaeal Tamaddonfard  , Amir Erfanparast , Farhad Soltanalinejad-Taghiabad |
| Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran |
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Abstract: (964 Views) |
Background and aim: Curcumin, the biologically active ingredient of turmeric (Curcuma longa), affects pain processing at different levels. Local mechanisms of action of curcumin are somewhat known, but the central effects at the spinal and supraspinal levels have been less investigated. In this study, the effect of oral administration of curcumin on the formalin-induced muscle pain was investigated. In addition, naloxone (a non-selective opioid receptor antagonist) and AM251 (a cannabinoid 1 receptor antagonist) were used to clarify the possible central mechanism of action of curcumin.
Methods: For intracerebroventricular (ICV) injections, one stainless steel guide cannula was implanted into in the left lateral ventricle of the brain in anaesthetized rats. Muscle pain was induced by intramuscular (IM) injection of formalin (2.5%, 50 µl) in the right gastrocnemius muscle, and the number of paw flinches and the time spent licking and biting of the injected paw were recorded at 5-min blocks for 1 h.
Results: A marked biphasic pain response was observed due to formalin injection. Oral administration of curcumin at doses of 25 and 100 mg/kg significantly (p < 0.01 and p < 0.001, respectively) decreased both phases of muscle pain. Pain intensity was not influenced by alone ICV injection of naloxone and AM251 (p > 0.05), whereas the suppressive effect of 100 mg/kg curcumin was inhibited by ICV administration of 2 µg naloxone and 2 µg AM251 (p < 0.001). All the above-mentioned treatments did not alter locomotor activity.
Conclusion: These results showed that curcumin produced an antinociceptive effect in muscle pain. Central opioid and cannabinoid receptors might be involved in the antinociception induced by curcumin.
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| Keywords: Lateral ventricle, Muscle pain, Curcumin, Opioid receptors, Cannabinoid receptors |
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Full-Text [PDF 1225 kb]
(428 Downloads)
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Type of Study: Original Research |
Subject:
Neuroscience
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