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 psychostimulant drug self-administration. The neuropeptide cholecystokinin (CCK) is co-localised with DA and inhibits nucleus accumbens (NAcc) DAergic neurotransmission via CCKB receptors.

Objectives: The present experiment was designed to examine the effects of intra-NAcc CCKB receptor stimulation on fixed-ratio (FR) amphetamine self-administration.

Methods: Wistar rats with intravenous catheters and NAcc cannulae were trained to self-administer amphetamine under a FR3 schedule of reinforcement. Animals performing stable self-administration were microinjected with pentagastrin and assessed during 3-h sessions.

Results: Intra-NAcc pentagastrin dose dependently increased amphetamine intake.

Conclusions: These results are consistent with the notion that NAcc CCKB receptor activation attenuates amphetamine reward.