The effect of mi opioid receptor agonists individually and in combination on pain behavior in rat model of neuropathic and inflammatory pain was assessed. Procedures of the sciatic nerve constriction and injection of formalin in animals were performed under general anesthesia. Morphine, fentanyl and buprenorphine were administered intraperitoneally. Pain behavior was assessed by the study of mechanical allodynia in the von Frey test, thermal hyperalgesia in the cold plate and tail-flick test, in the formalin model by assessing the number of pain behaviors.In the neuropathic pain model the effects of substances on the pain behavior after single and after multiple administrations were studied. Drug interactions studies were performed after co-administration of substances to assess the cross-tolerance and analgesic effectivness.Buprenorphine administered chronically intraperitoneally stronger than morphine and fentanyl inhibits mechanical allodynia and thermal hyperalgesia. There was no development of tolerance to the inhibition of mechanical allodynia by buprenorphine after repeated administrations, in contrast to morphine and fentanyl. In the case of thermal stimuli was observed development of tolerance to the test substances.The test substances in a different way induce cross-tolerance, morphine to the greatest extent, buprenorphine and fentanyl cause the development of cross-tolerance in selected behavioral tests only.In the inflammatory pain model, the influence of substances on pain behavior after single dose was assessed, then the interaction of substances given together was studied. Fentanyl in the second phase of testing potentiated pain behavior. Co-administration of substances potentiates their analgesic effects, buprenorphine inhibits fentanyl-induced hyperalgesia.
Feb 13, 2020
Mar 20, 2013
|ZB-117582||Feb 13, 2020|
Kościelniak-Merak, Barbara Karolina