Gabapentin enhances anti-nociceptive effects of morphine on heat, cold, and mechanical hyperalgesia in a rat model of neuropathic pain

Document Type : Original Article


1 Physiology Research Center, Kashan University of Medical Sciences, Kashan. Iran

2 Department of Pharmacology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran

3 Department of Pharmacology, School of Medicine, Kashan University of Medical Sciences, Kashan. Iran 5 Department of Pharmacology and Toxicology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran

4 Physiology Research Center, Kashan University of Medical Sciences, Kashan. Iran .Department of Pharmacology, School of Medicine, Kashan University of Medical Sciences, Kashan. Iran

5 Department of Addiction Studies, School of Medicine, Kashan University of Medical Sciences, Kashan. Iran Physiology Research Center, Kashan University of Medical Sciences, Kashan. Iran


Objective(s):Neuropathic pain is caused by lesions or diseases affecting the somatosensory system and often responds poorly to typical medications.  In this study, we evaluated anti-nociceptive effects of morphine, gabapentin and their combination on heat hyperalgesia, cold and mechanical allodynia in chronic constriction injury (CCI) model of neuropathic pain in rats.
Materials and Methods: Morphine (2, 4 and 8 mg/kg) and gabapentin (5, 10 and 20 mg/kg) were administered either alone or in combination (morphine 2 mg/kg and gabapentin 5 mg/kg).
Results:Our results showed that morphine and gabapentin alone produce anti-nociceptive effects at higher doses (morphine 4 and 8 mg/kg and gabapentin 10 and 20 mg/kg) whereas their combination resulted in better analgesia at lower doses as compared to other treatment groups (morphine 2 mg/kg or gabapentin 5 mg/kg).
Conclusion: These findings suggest that gabapentin potentiates the analgesic effects of morphine in the chronic constriction injury (CCI) model of neuropathic pain and combination of these drugs may be considered as a beneficial treatment for neuropathic pain.


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