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Analgesic effects of melatonin on post-herpetic neuralgia
Yun-Kun Deng1, Ji-Fei Ding2, Jin Liu3
1Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University Chengdu, Sichuan, China ; Department of Anesthesia, Guizhou Provincial Peopleas Hospital Guiyang 550002, China.
Objective:
This study aims to explore the analgesic effects of melatonin on post-herpetic neuralgia and its possible mechanism.
Methods:
A total of 48 PHN Wistar rats were divided into 4 groups randomly: Normal, PHN, PHN+MT and naloxone, 4P-PDOT or L-arginine+120 mg/kg MT (C). Heat pain latency was determined after MT injection for 20 min, 40 min, 80 min and 120 min respectively. The expression levels of δ receptor and MT2 receptor in different tissues of rats were detected by RT-PCR method. NO content was determined.
Results:
Heat pain latency in PHN rats were lower than that of control group (P<0.05), MT could increase the heat pain latency with dose-dependent, while naloxone, 4P-PDOT and L-arginine could reverse the analgesic effect of MT (P<0.05). The expression levels of δ receptor and MT2 receptor in spinal cord, hypothalamus and hippocampus in PHN+MT (120 mg/kg, i. p.) group were significantly higher than that of PHN group (P<0.05). The NO levels in the brain and spinal cord tissues in PHN group were higher than that of PHN+MT (120 mg/kg) group (P<0.05).
Conclusions:
MT had significant analgesic effects in the treatment of PHN, and its mechanism was closely related with δopioid receptor, NO and MT2 receptor.
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