DAMGO AND DPDPE FACILITATION OF BRAIN-STIMULATION REWARD THRESHOLDS IS BLOCKED BY THE DOPAMINE ANTAGONIST CIS-FLUPENTIXOL

The role of dopamine neurotransmission in opioid reward was investigat ed using a rate-independent measure for determining brain stimulation reward (BSR) thresholds. Intra-accumbens infusions of the mu- and delt a-specific peptides, D-Ala(2), N-Me-Phe(4), Gly-ol(5)-Enkephalin and D -Pen(2), D-Pen(5)-Enkephalin caused significant lowering of BSR thresh olds. The dopamine D1/D2 antagonist, cis-flupenthixol, blocked these e ffects at a dose that did not significantly alter thresholds when give n alone. These data suggest both mu- and delta-opioid potentiation of BSR is dopamine dependent. (C) 1997 Elsevier Science Ltd.