The dopamine receptor antagonist levo-tetrahydropalmatine attenuates heroin self-administration and heroin-induced reinstatement in rats

► Levo-tetrahydropalmatine attenuates heroin self-administration on the fixed-ratio 1 schedule. ► Levo-tetrahydropalmatine attenuates heroin-induced reinstatement of heroin-seeking behavior. ► Low doses of levo-tetrahydropalmatine do not affect locomotor activity.