title: Behavioral responses induced by repeated treatment with methamphetamine alone and in combination with scopolamine in rats.
abstract: Repeated amphetamine (A) or methamphetamine (M) treatment induces behavioral sensitization and drug conditioning. The present study compared behavioral sensitization and drug conditioning between treatments with M combined with scopolamine (S) and M alone with respect to a reciprocal balance between the dopaminergic and inhibitory cholinergic systems in rats. Repeated treatment with M (4.0 mg/kg i.p.) combined with S (0.5 mg/kg i.p.) (MS) produced progressive enhancement of stereotyped behavior, compared with repeated M treatment alone. Repeated MS treatment induced focussed stereotyped behavior that was elicited by every challenge injection of not only MS and M, but also partially by S. MS- but not M-sensitized rats exhibited conditioned responses to a tone (300 Hz, 100 dB) associated with drug state, suggesting that MS-induced pronounced behavioral sensitization may lead to an enhanced conditioned response to the conditioned stimulus (CS) of a tone. It is suggested that MS-induced behavioral sensitization may be mediated via a reciprocal balance between the dopaminergic and cholinergic systems in favor of a dopaminergic dominance, and that such a balance may be involved in the conditioning to the drug-associated tone CS.
authors.affiliation: Urawa Juvenile Classification Home, Ministry of Justice, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yui
authors.forename: T
authors.initials: T
authors.lastname: Miura
mesh_terms: D000818:Animals; D001143:Arousal / Q000187:drug effects; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000502:physiology; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003214:Conditioning, Classical / Q000187:drug effects*; D015259:Dopamine Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D007274:Injections, Intraperitoneal; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D015259:Dopamine Agents; D018727:Muscarinic Antagonists; D008694:Methamphetamine; D012601:Scopolamine