Ontogeny of striatal dopamine release in rats after acute administration of methamphetamine

In the present study, we examined the effects of acute MAP administration on striatal extracellular levels of dopamine (DA) and its metabolites in groups of rats on postnatal days (PNDs) 14, 21, 28, and 56. A single injection of 4 mg/kg MAP (IP) induced increase in extracellular DA and decrease in extracellular 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatal perfusates of rats on all PNDs examined. The magnitude of increase in DA concentrations at 20 min after the MAP injection was significantly smaller on PND 14 than PNDs 21, 28, and 56, whereas the magnitude of decrease in DOPAC concentrations after the MAP injection was significantly smaller on PND 14 than PNDs 21, 28, and 56. After the MAP injection, homovanillic acid levels decreased on PNDs 21, 28, and 56, but increased on PND 14. These results suggest that rats on PND 14 differ from those thereafter in MAP-induced DA release and changes in its metabolites, and that such developmental effect on MAP-induced DA release may be involved in the ontogeny of MAP-induced behavioral sensitization.