PD-168077 maleate is a selective dopamine D4 receptor agonist, with a Ki of 9 nM.
PD-168077 is one of the first agents to be identified as putative selective D4 agonists. It shows >100-fold selectivity over other members of the D2-like receptor family and over their D1-like counterparts; PD-168077 shows a 20-fold selectivity over α1, and α2, a 45-fold selectivity over 5-HT1A, and a 460-fold selectivity over 5-HT2A receptors; PD-168077 evidences intrinsic activity at the D4 receptor in terms of quinpirole-like inhibition of forskolin-stimulated cAMP accumulation or stimulation of [3H]thymidine uptake in CHO cells expressing the human D4 receptor[1]. In the PD-168077-treated cell, p-CaMKII exhibits a significantly increased clustering at synaptic sites, as indicated by the enhanced colocalization with PSD-95[2].
PD-168077 (0.2-25.0 mg/kg) dose-dependently induces locomotion, which takes an unusual and characteristic ”shuffling” form with uncoordinated movements together with yawning, and episodes of myoclonic jerking; grooming, and rearing are reduced[1].
References:
[1]. Clifford JJ, et al. Topographically based search for an "Ethogram" among a series of novel D(4) dopamine receptor agonists and antagonists. Neuropsychopharmacology. 2000 May;22(5):538-44.
[2]. Gu Z, et al. Activation of dopamine D4 receptors induces synaptic translocation of Ca2+/calmodulin-dependent protein kinase II in cultured prefrontal cortical neurons. Mol Pharmacol. 2006 Mar;69(3):813-22.