Antinociceptive Effect of Morphine Microinjections into the Dorsal Hippocampus in the Formalin-Induced Orofacial Pain in Rats
Publish place: Veterinary Research Forum، Vol: 1، Issue: 2
Publish Year: 1389
نوع سند: مقاله ژورنالی
زبان: English
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شناسه ملی سند علمی:
JR_VRFAN-1-2_003
تاریخ نمایه سازی: 25 آبان 1402
Abstract:
In the present study, the effects of intra-hippocampal microinjections of morphine (an opioid agonist) and naloxone (an opioid antagonist) were investigated in the formalin-induced orofacial pain in rats. Orofacial pain was induced by subcutaneous injection of formalin (۱ %, ۵۰ μl) in the upper lip region and the time spent of face rubbing was measured in ۳-min blocks for ۴۵ min. Formalin induced a biphasic (first phase: ۰-۳ min; second phase: ۱۵-۳۳ min) pain response. Intra-hippocampal microinjections of morphine at doses of ۲ and ۴ μg significantly (P < ۰.۰۵) attenuated the first phase, and at doses of ۱, ۲ and ۴ μg, morphine significantly (P < ۰.۰۵) suppressed both phases of formalin-induced orofacial pain response. Intra-hippocampal microinjections of naloxone (۱ and ۴ μg) non-significantly increased pain when used alone, and in pretreatment microinjection, naloxone (۴ μg) reversed morphine (۲ μg)-induced antinociception. These results indicate that at the level of hippocampus of the brain, morphine through a naloxone-reversible mechanism produced an antinociceptive effect confronting the pain induced by formalin in the orofacial region in rats.
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Authors
Amir Erfanparast
Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
Esmaeal Tamaddonfard
Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
Amir Abbas Farshid
Department of Pathobiology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
Emad Khalilzadeh
Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran