The analgesic and respiratory depressant actions of metorphamide in mice and rabbits.
Metorphamide (MET) elicited a potent, dose-dependent analgesia and respiratory depression in mice and rabbits. MET induced-analgesia was naloxone reversible and potentiated by bestatin. Naloxonazine, a relatively selective mu 1 blocker, at certain dosage (50 micrograms per rabbit, icv), could abolish the analgesia but not the respiratory inhibition produced by MET. Our result indicates that mu 1 receptors mediate the MET induced-analgesia but not its respiratory effect. Since MET is a mu- and kappa-ligand with very low delta activity, the MET induced respiratory depression may be mediated by mu 2 or kappa binding sites.
D000700:Analgesics; D000818:Animals; D003864:Depression, Chemical; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005260:Female; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009270:Naloxone / Q000031:analogs & derivatives / Q000494:pharmacology; D011817:Rabbits; D012119:Respiration / Q000187:drug effects*; D012684:Sensory Thresholds
D000700:Analgesics; D009270:Naloxone; D004744:Enkephalin, Methionine; C034643:naloxonazine; C039700:adrenorphin