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. Author manuscript; available in PMC: 2010 Sep 8.
Published in final edited form as: Brain Res. 2009 Jul 9;1288:42–49. doi: 10.1016/j.brainres.2009.06.094

Fig. 4. Effect of the combined dextromethorphan and melatonin treatment on pain behavior in WKY rats.

Fig. 4

A combination of 15 mg/kg DM and 30 mg/kg melatonin given intraperitoneally once daily for a week was more effective than either drug alone in reducing neuropathic pain behaviors. The combination significantly reduced thermal hyperalgesia (P< 0.05, Fig. 4a) and mechanical allodynia (P< 0.05, Fig. 4b), as compared with their corresponding baseline. Mel30, DM15, Mel30DM15: 30 mg/kg melatonin, 15 mg/kg DM, and 30 mg/kg melatonin combined with 15 mg/kg DM, respectively; Bas, Baseline; CCI1w, 1 week after CCI; T1w, 1 week after CCI followed by 1-week treatment with vehicle, melatonin (Mel) or dextromethorphan (DM) alone, or their combination. *, P<0.05, as compared with baseline in the same group; +, P<0.05 as compared with CCI1w in the same group.