The role of neurokinin-1receptor in anti-nociceptive effect of inhalation anesthetics in mice

Abstract

：Objective To investigatethe role of neurokinin-1 receptor (NK-1R) in the anti-nociceptive effect of enflurane,isoflurane and sevoflurane in mice. Methods Three hundred and twenty Kunming mice of bothsexes weighing 20-25 g were randomly divided into4 groups (n =80 each): group normalsaline (group NS);group enflurane (group E); group isoflurane (group I) and groupsevoflurane (group S). Normal saline (NS) 1.0ml/kg, erflurane 0.5 ml/kg, isoflurane 0.4ml/kg and sevoflurane 2.0 ml/kg were injected intraperitoneally in NS,E,I and S groupsrespectively. Each group was further divided into 4 subgroups receiving intrathecal NS 5 μl and Sar-SP (NK-IR agonist) 20,40 and 80 ng respectively at 5 min after intraperitoneal injection of inhalationanesthetics. The anti-nociceptive effect of the inhalation anesthetics was assessed bytail flick latency (TFL) (the latency for removal of the tail from the path of heatsource) and paw-licking time (PLT) after intraplantar formalin injection. Resultslntraperitoneal enflurane, isoflurane and sevoflurane significantly prolonged TFL andshortened PLT. Intrathecal Sar-SP 20, 40 and 80 ng significantly shortened TFLdose-dependently but had no significant effeet on PLT as compared with control subgroup.Conclusion NK-1R is involved in the anti-nociceptive effect of enflurane, isoflurane andsevofluran on thermal pain but not chemical and inflammatory pain. Key words: Receptors, neurokinin-1; Spinal cord; Anesthetics,inhalation; Analgesia