Subchronic methamphetamine treatment enhances methamphetamine- or cocaine-induced dopamine efflux in vivo.
Intracerebral dialysis was used to study the mechanism underlying behavioral sensitization. Rats were divided into two groups: a control group that received intraperitoneal injections of saline and an experimental group that was given methamphetamine (MAP) (4 mg/kg) once a day for 14 days. Seven days after the last injection, dopamine (DA) and its metabolites were measured in striatal dialysates obtained from awake freely moving rats. A challenge injection of MAP (4 mg/kg) caused a marked increase in the extracellular concentrations of DA, and the extent of the increase was significantly greater in MAP-pretreated rats than in the saline-pretreated controls. A challenge injection of cocaine (20 mg/kg) also caused a significantly greater increase in extracellular DA levels in MAP-pretreated rats than in saline-pretreated rats. These results suggest that an enhancement in striatal DA efflux may play an important role in MAP-induced behavioral sensitization and cross-sensitization to cocaine.
Kazahaya
Y
Y
Department of Neuropsychiatry, Okayama University Medical School, Japan.
Akimoto
K
K
Otsuki
S
S
D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D003342:Corpus Striatum / Q000187:drug effects*; D004298:Dopamine / Q000378:metabolism*; D004357:Drug Synergism; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013239:Stereotyped Behavior / Q000187:drug effects
D011954:Receptors, Dopamine; D008694:Methamphetamine; D003042:Cocaine; D004298:Dopamine