Receptor binding autoradiography, using the selective ligand [3H]7-OH-(R)DPAT (R(+)-2-dipropylamino-7-hydroxy 1,2,3,4-tetrahydronaphthalene), showed that piribedil is a potent inhibitor at dopamine D3 receptors in limbic regions (island of Calleja), with affinity (IC50) between 30 and 60 nM. The in vitro IC50 of piribedil for inhibition of [3H]spiperone binding to receptors of the dopamine D2-like family (D2, D3 and D4), ranged between 10-7 and 10-6 M in different brain regions (medial and lateral caudate putamen, olfactory tubercles, and nucleus accumbens). At the highest concentration tested (10-5 M) piribedil inhibited dopamine D1 receptor binding by 2 than for dopamine D2-like receptors, and very low affinity for the dopamine D1 receptor subtype in rat brain. How this pattern of receptor affinity is related to the pharmacological profile of piribedil deserves further investigation.
- Dopamine receptor
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience