Enhanced extracellular dopamine level may be the fundamental neuropharmacological basis of cross-behavioral sensitization between methamphetamine and cocaine--an in vivo dialysis study in freely moving rats.

Intracerebral dialysis was used to study the mechanism underlying cross-behavioral sensitization between methamphetamine (MAP) and cocaine. The challenge injection of cocaine caused a significantly greater increase in striatal perfusate dopamine (DA) levels in MAP-pretreated rats than in saline-pretreated rats. Similarly, the challenge injection of MAP caused a significantly greater increase in extracellular DA levels in cocaine-pretreated rats than in control rats. These results suggest that an enhancement in striatal DA efflux may play an important role in cross-behavioral sensitization between MAP and cocaine.