Dynamic dopaminergic regulation of neuropeptide Y systems in discrete striatal and accumbens regions

In this study we evaluated the effects of multiple administrations of selective dopamine D1 and D2 receptor agonists and antagonists on striatal, nigral, accumbens, pallidal and cortical neuropeptide Y systems. Treatment with the D1 receptor agonist, SKF 38393, decreased, while that with the D1 receptor antagonist, SCH 23390, increased neuropeptide Y-like immunoreactivity in the globus pallidus and several regions within the caudate-putamen. SCH 23390 did not change accumbens neuropeptide Y-like immunoreactivity levels but SKF 38393 increased neuropeptide Y-like immunoreactivity levels in anterior and decreased neuropeptide Y-like immunoreactivity levels in the posterior nucleus accumbens. Interestingly, reductions in neuropeptide Y-like immunoreactivity content occurred in response to administrations of both D2 receptor agonist, quinpirole, or antagonist, sulpiride, in all identified regions of each structure at some time point. These data suggest that the neuropeptide Y systems studied may be regulated by selective activity at postsynaptic or presynaptic dopamine receptors. They further suggest that within structures such as the caudate-putamen and nucleus accumbens are multiple distinct neuropeptide Y systems which are uniquely influenced by dopamine receptors.