NEUROPEPTIDE-Y - INTRAACCUMBENS INJECTIONS PRODUCE A PLACE PREFERENCETHAT IS BLOCKED BY CIS-FLUPENTIXOL

Neuropeptide Y (NPY) has been localized in the nucleus accumbens (NAcc ), where it may influence dopamine (DA) neurotransmission. Extensive d ata implicate NAcc DA in reward-related learning, raising the possibil ity that NPY microinjected into the NAcc may induce rewarding effects mediated by DA. This hypothesis was tested using the conditioned place preference (CPP) paradigm. Each experiment consisted of three distinc t phases: preconditioning (three 15-min exposures to an apparatus with two compartments connected by a tunnel); conditioning (four 30-min pa irings of one compartment with drug and four similar pairings of the o ther compartment with vehicle); and test (three 15-min exposures to th e apparatus). A significant increase in the time spent in the drug-pai red compartment from preconditioning to test was taken as evidence of a CPP. Two experiments showed that systemic (2.0 mg/kg, IP) or intraac cumbens amphetamine (10.0 mug in 0.5 mul on each side) produced a CPP. The third experiment showed that intraaccumbens NPY (0.1 mug in 0.5 A l on each side) produced a CPP. This CPP was blocked by pretreatment w ith a dose of the DA receptor blocker cis-flupenthixol (20.0 mug in 0. 5 mul on each side in the NAcc) that, alone, produced no CPP effect. T hese results strongly suggest that NPY applied to the NAcc is rewardin g. In addition, these rewarding properties of NPY may be mediated by D A neurotransmission.