WAY-100635 is a potent dopamine D4 receptor agonist.
OBJECTIVE
WAY-100635 is a prototypical 5-HT1A receptor antagonist and has been used widely as a pharmacological probe to investigate the distribution and function of 5-HT1A receptors. Results from our studies suggested that WAY-100635 was potently inducing effects unrelated to its 5-HT1A receptor affinity. In the present work, we evaluated the in vitro pharmacology of this compound at two D2-like receptor subtypes.


METHODS
The functional properties and binding affinities of WAY-100635 were evaluated in HEK 293 cells stably expressing dopamine D2L or D4.4 receptors.


RESULTS
Initial screens performed by the NIMH Psychoactive Drug Screening Program indicated that WAY-100635 displayed 940, 370, and 16 nM binding affinities at D2L, D3, and D4.2 receptors, respectively. Subsequent saturation analyses demonstrated that the Kd of [3H]WAY-100635 at D4.2 receptors was 2.4 nM, only tenfold higher than 5-HT1A. WAY-100635 and its major metabolite, WAY-100634, were potent agonists in HEK-D4.4 cells (EC50=9.7+/-2.2 and 0.65+/-0.2 nM, respectively). WAY-100635 behaved as a full agonist, and WAY-100634 was a nearly full agonist. In HEK-D2L cells, WAY-100635 weakly antagonized the effects of 300 nM quinpirole. Subsequent radioligand binding studies confirmed that WAY-100635 possesses high affinity for D4.4 receptors but binds weakly to D2L receptors (3.3+/-0.6 and 420+/-11 nM, respectively).


CONCLUSIONS
This study demonstrates that WAY-100635 is not a "selective" 5-HT1A receptor antagonist, as previously reported, and conclusions drawn from studies that employed WAY-100635 as a selective 5-HT1A antagonist may need to be reevaluated.
Chemel
Benjamin R
BR
Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907-2091, USA.
Roth
Bryan L
BL
Armbruster
Blaine
B
Watts
Val J
VJ
Nichols
David E
DE
D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D018491:Dopamine Agonists / Q000494:pharmacology*; D006801:Humans; D010879:Piperazines / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D011869:Radioligand Assay; D050638:Receptors, Dopamine D4 / Q000819:agonists*
D018491:Dopamine Agonists; D010879:Piperazines; D011725:Pyridines; D050638:Receptors, Dopamine D4; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D000242:Cyclic AMP