Analgesic effects of melatonin on post-herpetic neuralgia.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
melatonin (MT) | increase | heat pain latency | PHN Wistar rats | dose-dependent | could increase | #1 |
naloxone | decrease | analgesic effect of MT | PHN Wistar rats | - | could reverse | #2 |
4P-PDOT | decrease | analgesic effect of MT | PHN Wistar rats | - | could reverse | #3 |
L-arginine | decrease | analgesic effect of MT | PHN Wistar rats | - | could reverse | #4 |
melatonin (MT) (120 mg/kg, i. p.) | increase | expression levels of δ receptor | PHN Wistar rats | - | were significantly higher | #5 |
melatonin (MT) (120 mg/kg, i. p.) | increase | expression levels of MT2 receptor | PHN Wistar rats | - | were significantly higher | #6 |
melatonin (MT) (120 mg/kg) | decrease | NO levels | PHN Wistar rats | - | were higher than | #7 |
melatonin (MT) | decrease | post-herpetic neuralgia (PHN) | PHN Wistar rats | - | had significant analgesic effects | #8 |
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.