Tamaddonfard Esmaeal, Erfanparast Amir, Taati Mina, Dabbaghi Milad
Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran;
DVM student, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
Vet Res Forum. 2014 Winter;5(1):49-54.
Calcium, through its various channels involves in local, spinal and supra-spinal transmission of pain. In the present study, we investigated the separate and combined treatment effects of verapamil (a calcium channel blocker), morphine (an opioid agonist) and naloxone (an opioid antagonist) on pain in the orofacial region of rats. Orofacial pain was induced by subcutaneous (SC) injection of formalin (50 µL, 1.5%) into the left upper lip side, and the time durations spent face rubbing with epsilateral forepaw were recorded in three min blocks for a period of 45 min. Formalin induced a biphasic pattern (first phase: 0-3 min; second phase: 15-33 min) of pain. Intraperitoneal (IP) injections of verapamil (2 and 8 mg kg(-1)) and morphine (2 and 4 mg kg(-1)) suppressed orofacial pain. Co-administration of sub-analgesic doses of verapamil (0.5 mg kg(-1)) and morphine (1 mg kg(-1)) produced second phase analgesia. Both phases of formalin-induced pain were suppressed when an analgesic dose (2 mg kg(-1)) of verapamil co-administered with a sub-analgesic dose (1 mg kg(-1)) of morphine. The SC injection of naloxone (2 mg kg(-1)) alone with no effect on pain intensity, prevented the antinociceptive effects induced by morphine (2 mg kg(-1)), but not verapamil (2 mg kg(-1)). The obtained results showed antinociceptive effects for verapamli and morphine on orofacial pain. Co-administrations of verapamil and morphine produced antinociceptive effects. It seems that opioid analgesic system may not have a role in the verapamil-induced antinociception.
钙通过其各种通道参与疼痛的局部、脊髓和脊髓上传递。在本研究中，我们研究了维拉帕米（一种钙通道阻滞剂）、吗啡（一种阿片类激动剂）和纳洛酮（一种阿片类拮抗剂）单独及联合治疗对大鼠口腔颌面部疼痛的影响。通过将福尔马林（50 μL，1.5%）皮下注射到左上唇侧诱导口腔颌面部疼痛，并在45分钟内以3分钟为一个时间段记录用同侧前爪擦脸的持续时间。福尔马林诱导出双相疼痛模式（第一阶段：0 - 3分钟；第二阶段：15 - 33分钟）。腹腔注射维拉帕米（2和8 mg kg⁻¹）和吗啡（2和4 mg kg⁻¹）可抑制口腔颌面部疼痛。亚镇痛剂量的维拉帕米（0.5 mg kg⁻¹）和吗啡（1 mg kg⁻¹）联合给药产生第二阶段镇痛作用。当镇痛剂量（2 mg kg⁻¹）的维拉帕米与亚镇痛剂量（1 mg kg⁻¹）的吗啡联合给药时，福尔马林诱导的疼痛的两个阶段均受到抑制。皮下注射纳洛酮（2 mg kg⁻¹）单独对疼痛强度无影响，但可阻止吗啡（2 mg kg⁻¹）诱导的抗伤害感受作用，而对维拉帕米（2 mg kg⁻¹）诱导的抗伤害感受作用无影响。所得结果表明维拉帕米和吗啡对口腔颌面部疼痛具有抗伤害感受作用。维拉帕米和吗啡联合给药产生抗伤害感受作用。似乎阿片类镇痛系统可能在维拉帕米诱导的抗伤害感受中不起作用。
