Fig. 5.
Age differences in the time course and frequency dependence of methylphenidate and amphetamine effects on dopamine overflow in caudate of anesthetized rats. Drug effects are expressed as a percentage of the change in DAmax (drug/predrug baseline). For methylphenidate, [DA]max was averaged across groups of PN28 (n = 5) and PN65 (n = 5) rats and for 1 mg/kg amphetamine, PN28 (n = 6) and PN65 (n = 7) rats. The drug effects were first determined at 1 min after injection and then at 2.5, 5, 7.5, 10, and 30 min. The dashed lines serve as a visual reference for the baseline values. *, p < 0.05, significantly different from the corresponding age group.