title: The role of the mu 2-opioid receptor in the antitussive effect of morphine in mu 1-opioid receptor-deficient CXBK mice.
abstract: The effect of morphine on the capsaicin-induced cough reflex was studied in mu 1-opioid receptor-deficient CXBK mice. There was no significant difference between the morphine-induced antitussive effect in CXBK mice and C57BL/6 mice, a progenitor strain. Furthermore, the antitussive effects of morphine in both the CXBK and C57BL/6 mice were antagonized by pretreatment with either naloxone or beta-funaltrexamine, a mu-opioid receptor antagonist, whereas pretreatment with naltrexonazine, a selective mu 1-opioid receptor antagonist, had no effect. Moreover, naltrindole, a selective delta-receptor antagonist, also had no significant effect on the antitussive effects of morphine in either CXBK or C57BL/6 mice. These results support our previous hypothesis that mu 2- rather than mu 1-opioid receptors are involved in morphine-induced antitussive effects.
authors.affiliation: Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Kamei
authors.forename: Y
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Misawa
authors.forename: H
authors.initials: H
authors.lastname: Nagase
authors.forename: Y
authors.initials: Y
authors.lastname: Kasuya
mesh_terms: D000818:Animals; D000996:Antitussive Agents / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000494:pharmacology*; D017450:Receptors, Opioid, mu / Q000032:analysis / Q000187:drug effects / Q000502:physiology*
chemical_list: D000996:Antitussive Agents; D017450:Receptors, Opioid, mu; D009020:Morphine