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 D 1 and D 2 receptor agonists and antagonists on striatal, nigral, accumbens, pallidal and cortical neuropeptide Y systems. Treatment with the D 1 receptor agonist, SKF 38393, decreased, while that with the D 1 receptor antagonist, SCH 23390, increased neuropeptides 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 D 2 receptor agonist, quinpirole, or antagonist, sulpiride, in all identified regions of eacj 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.