Single and multiple high-dose administrations of
methamphetamine (METH) differentially decrease
dopamine (DA) transporter (DAT) function, as assessed by measuring [(3)H]DA uptake into rat striatal synaptosomes prepared 1 h
after treatment. Prevention of METH-
induced hyperthermia attenuated the decrease in DAT activity induced by multiple
injections of the stimulant. Likewise, this decrease was attenuated by previous depletion of striatal DA levels using
alpha-methyl-p-tyrosine (alphaMT) or pretreatment with the D1 and D2 antagonists
SCH-23390 and
eticlopride, respectively. However, METH-
induced hyperthermia was also blocked by alphaMT and
eticlopride. Reinstatement of
hyperthermia to alphaMT- or
eticlopride-pretreated rats partially restored the METH-induced decrease in DAT activity. In contrast, neither prevention of METH-
induced hyperthermia depletion of DA, nor DA antagonists altered the decrease in DAT function induced by a single administration of METH. Pretreatment with the
antioxidant N-t-butyl-alpha-phenylnitrone prevented part of the decrease in DAT function associated with multiple, but not a single, METH
injections. Although not tested directly, additional data presented here suggest that the reduction in DAT activity induced by a single METH administration constitutes a part of the total reduction observed immediately after multiple administrations. Taken together, the results indicate that DA,
hyperthermia, and
oxygen radicals contribute to a component of the rapid decrease in DAT function induced by multiple
injections of METH but do not appear to be associated with the reduction induced by a single administration of the stimulant.