High‐throughput screening for novel allosteric modulators of the D1 dopamine receptor (662.4)

Dopamine is a critically important neurotransmitter in the CNS and peripheral nervous system, with five receptor subtypes mediating its effects. Importantly, D1 receptor (D1R)‐selective agents may prove beneficial in the treatment of many neuropsychiatric disorders. In an effort to identify novel selective allosteric modulators of the D1R we used a high throughput screening approach. 380,000 small molecules in the NIH Molecular Libraries Screening Center Network library were screened using a cell line expressing the D1R coupled to G15 resulting in a robust Ca2+ signal upon receptor stimulation. Hit compounds were triaged through secondary functional and radioligand displacement binding assays to determine subtype selectivity and their allosteric versus orthosteric nature. We initially identified 96 putative positive allosteric modulator (PAM) hits that enhanced the EC20 activity of dopamine in the Ca2+ response ‐ 6 of these were subsequently confirmed during triage and were chosen for further characterization. In addition we found approximately 115 agonist and 125 antagonist hits that failed to completely inhibit radioligand binding and have been classified as potential allosteric agonists and antagonists or negative allosteric modulators (NAMs). These compounds are currently being characterized using additional assays to confirm their selectivity, activity, and classification. Grant Funding Source : NINDS Intramural Program