Reduced apomorphine sensitivity of dopamine metabolism in rat striatum after repeated administration of methamphetamine.
Rats received daily injections of saline or methamphetamine (MAP; 4 mg/kg/day) for 14 days. Seven days after the completion of this regime, dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels were measured in the striatum following intraperitoneal injections of either saline plus gamma-butyrolactone (GBL; 750 mg/kg) or apomorphine (2 mg/kg) plus GBL. The saline plus GBL challenges produced no difference in the DA or DOPAC levels between saline- and MAP-treated rats. By contrast, the apomorphine plus GBL challenges produced higher DOPAC levels in MAP-treated rats than saline-treated rats, although they produced no difference in the DA levels between the two groups. These results indicate that apomorphine depresses the striatal DA metabolism less in MAP-treated rats than in saline-treated control rats. Repeated MAP administration might produce this effect through apomorphine subsensitivity of presynaptic DA autoreceptors.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000818:Animals; D001058:Apomorphine / Q000378:metabolism*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D008297:Male; D008694:Methamphetamine / Q000008:administration & dosage*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D015102:3,4-Dihydroxyphenylacetic Acid; D008694:Methamphetamine; D001058:Apomorphine; D004298:Dopamine