Self-administration of intravenous amphetamine: effect of nucleus accumbens CCKB receptor activation on fixed-ratio responding

Rationale: The mesolimbic dopamine (DA) system is implicated in psychostimu lant drug self-administration. The neuropeptide cholecystokinin (CCK) is co -localised with DA and inhibits nucleus accumbens (NAcc) DAergic neurotrans mission via CCKB receptors. Objectives: The present experiment was designed to examine the effects of intra-NAcc CCKB receptor stimulation on fixed-ra tio (FR) amphetamine self-administration. Methods: Wistar rats with intrave nous catheters and NAcc cannulae were trained to self-administer amphetamin e under a FR3 schedule of reinforcement. Animals performing stable self-adm inistration were microinjected with pentagastrin and assessed during 3-h se ssions. Results: Intra-NAcc pentagastrin dose dependently increased ampheta mine intake. Conclusions: These results are consistent with the notion that NAcc CCKB receptor activation attenuates amphetamine reward.