31. Therapeutic morphine prolongs neuropathic pain in rats: A role for TLR4 and inflammasome signaling in the lumbar spinal cord

Microgliosis occurs after morphine and peripheral nerve injury alone, but the behavioral and molecular impact in tandem is unknown. We hypothesized that sciatic chronic constriction injury (CCI)-allodynia would be enhanced by subsequent repeated morphine in rats, involving TLR4, P2X7 receptor (P2X7R) and caspase-1, facilitating release of interleukin (IL)-1β. Beginning 10 days after CCI, morphine (5 mg/kg b.i.d.) or saline was administered for 5 days. Compared to vehicle, morphine significantly prolonged the duration of CCI-induced allodynia ( n  = 6/group; p p n  = 6/group; p n  = 6/group; p p