Journal of anesthesia
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Journal of anesthesia · Apr 2010
Involvement of the kappa-opioid receptor in nitrous oxide-induced analgesia in mice.
Nitrous oxide (N(2)O)-induced analgesia is thought to be mediated by endogenous opioids. We previously showed that the mu-opioid receptor is not required for the analgesic action of N(2)O in mice using a gene knockout approach. In this study, we examined the effect of kappa- (KOP)- or delta-opioid receptor (DOP)-selective antagonists on N(2)O-induced analgesia. ⋯ Nor-BNI [10 mg kg(-1), subcutaneously (s.c.)] significantly suppressed the analgesic effect of N(2)O and U50488. In contrast, NTI (10 mg kg(-1) s.c.) did not significantly affect the analgesic action of N(2)O, but almost completely inhibited the analgesic effect of SNC80. These results suggest that KOP plays an important role in the analgesic effect of N(2)O in mice.