Possible involvement of mu 2-mediated mechanisms in mu-mediated antitussive activity in the mouse.
The effect of pretreatment with naloxonazine on mu-opioid agonist-mediated antitussive effects was studied in mice. The antitussive effects of [D-Ala2, MePhe4, Gly-ol5]enkephalin (DAMGO) and morphine were significantly antagonized by naloxone pretreatment, 1 mg/kg given i.p. 5 min earlier, but not by naloxonazine pretreatment, 35 mg/kg given s.c. 24 h earlier. In contrast, the antinociceptive effects of these mu agonists, as determined by the tail-flick method, were significantly reduced by pretreatment with both naloxone and naloxonazine. These results suggest that mu 2 rather than mu 1 mechanisms are involved in mu-mediated antitussive effects.
Kamei
J
J
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
Iwamoto
Y
Y
Kawashima
N
N
Suzuki
T
T
Nagase
H
H
Misawa
M
M
Kasuya
Y
Y
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D000996:Antitussive Agents / Q000494:pharmacology*; D002211:Capsaicin; D003371:Cough / Q000139:chemically induced; D004305:Dose-Response Relationship, Drug; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000031:analogs & derivatives* / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects; D017450:Receptors, Opioid, mu / Q000187:drug effects*
D000700:Analgesics; D000996:Antitussive Agents; D004745:Enkephalins; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone; D009020:Morphine; C034643:naloxonazine; D002211:Capsaicin