Neuropathic pain attenuating effects of perampanel in an experimental model of chronic constriction injury in rats

The present study explores the pain attenuating effect of perampanel, AMPA receptor antagonist, in chronic constriction injury-induced neuropathic pain. Chronic Constriction Injury was performed by putting four loose ligatures around the sciatic nerve. Pain was assessed by determining mechanical hyperalgesia, cold allodynia and heat hyperalgesia on 7th and 14th day post surgery. Perampanel (3 mg and 6 mg/kg, p.o.) was administered 30 min before pain assessment test on 14th day post-surgery. CCI led to significant development of pain and peak symptoms were observed on 14th day. Perampanel significantly attenuated CCI-induced mechanical hyperalgesia, cold allodynia and heat hyperalgesia, at different time intervals 30, 60, 90, 120 min, with more substantial effect observed at dose of 6 mg/kgNaloxone was administered in CCI subjected rats before perampanel treatment to explore the potential role of opioids in anti-nociceptive effects of perampanel. Naloxone decreased the pain attenuating effects of perampanel significantly, indicating a critical role of opioid system in anti-nociceptive potential of perampanel. Perampanel has pain attenuating potential in CCI-induced neuropathic pain, which may be due to partly mediated through the opioid system.