REPEATED ADMINISTRATION OF 3,4-METHYLENEDIOXYMETHAMPHETAMINE AUGMENTSCOCAINE ACTION ON DOPAMINE IN THE NUCLEUS-ACCUMBENS - A MICRODIALYSISSTUDY

In this study, we examined the ability of a single injection of cocain e (20 mg/kg, i.p.) to augment extracellular dopamine levels in the nuc leus accumbens two weeks after pretreating rats with either saline (1 ml/kg, i.p.) or the serotonin neurotoxin 3,4-methylenedioxymethampheta mine (20 mg/kg, s.c., twice daily for 4 days). The level of dopamine i n the nucleus accumbens was measured using in vivo microdialysis. Coca ine produced a 400% increase in extracellular nucleus accumbens dopami ne levels in control rats, whereas in 3,4-methylenedioxymethamphetamin e treated rats the increase produced by cocaine was 800%, which was si gnificantly different from controls. This suggests that 3,4-methylened ioxymethamphetamine, a relatively common drug of abuse, may alter subs equent vulnerability to cocaine dependence and abuse. (C) 1997 Elsevie r Science B.V.