title: Independent effects of morphine and apomorphine on stereotyped gnawing in the hamster.
abstract: Eight experiments were conducted to investigate the effects of apomorphine, a dopaminergic agonist, and of morphine, an opiate, on stereotyped behavior in the hamster. Animals were observed at two minute intervals for one hour and incidents of stereotyped gnawing, licking and sniffing were recorded using a time-sampling method. Both morphine and apomorphine produced dose-related increases in stereotyped gnawing. A low dose of the opiate antagonist, naloxone (0.4 mg/kg), blocked morphine-induced gnawing but neither that dose nor higher doses of naloxone (1, 4 and 10 mg/kg) blocked apomorphine-induced gnawing. A low dose of the dopaminergic antagonist, haloperidol (0.05 mg/kg), blocked apomorphine-induced gnawing but did not block morphine-induced gnawing. Further experiments indicated that morphine administration did not sensitize, or influence in any way, subsequent apomorphine-induced stereotyped behavior.
authors.affiliation: Department of Psychology, University of Southern Colorado, Pueblo 81001-4901.
authors.forename: P
authors.initials: P
authors.lastname: Schnur
authors.forename: R A
authors.initials: RA
authors.lastname: Martinez
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005260:Female; D008647:Mesocricetus; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D013239:Stereotyped Behavior / Q000187:drug effects*; D013997:Time Factors
chemical_list: D009270:Naloxone; D009020:Morphine; D001058:Apomorphine