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Effect of capsaicin (TRPV1 receptor agonist( injection into the periaqueductal gray region on morphine antinociception in sterptozotocin induced diabetic rats using tail flick test
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Masoomeh Taheri Azandaryani *   , Abdolrahman Sarihi , Alireza Komaki , Amir Hossein Emam |
| Department of Biology, Hamedan Branch, Islamic Azad University, Hamadan, Iran |
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Abstract: (15814 Views) |
Introduction: Neuropathy exists in many diabetic patients. The role of Periaqueductal Gray (PAG) region in pain modulation has long been investigated. Opioid and transient receptor potential vanilloid 1 (TPRV1) receptors are distributed in PAG. In this study, the role of intra-PAG injection of capsaicin on morphine analgesia was investigated in diabetic rats.
Methods: Twenty-four male Wistar rats (200-250g) were used in this study. Diabetes mellitus was induced by single i.p. injection of streptozotocin 60 mg/kg. Using stereotaxic surgery, a guide cannula was implanted in PAG. Twenty-eight days after STZ administration, neuropathy was confirmed by Von frey and hot plate tests. On day 29, morphine (5 mg/kg) was injected subcutaneously to diabetic rats. Capsaicin (10 nmol/µl) was injected into PAG 15 min later. Tail flick test was performed 5 min thereafter. Tail-flick latency was measured at 15, 30, 45 and 60 min after capsaicin administration.
Results: Von frey and hot plate tests confirmed the hyperalgesia in diabetic rats. Capsaicin microinjection increased morphine analgesia at 15, 30, 45 and 60 minutes after injection in diabetic rats.
Conclusion: It seems that activation of the TRPV1 receptors in PAG potentiates antinociceptive effect of morphine in diabetic rats. This study confirmed evidences indicating the interaction between capsicinoid and opioidergic systems in pain analgesia regulatory system.
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| Keywords: Diabetic rats, Neuropathy, Periaqueductal gray, Streptozotocin, TRPV1 receptor |
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Full-Text [PDF 1063 kb]
(2243 Downloads)
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Type of Study: Original Research |
Subject:
Neuroscience
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