title: Pharmacological characterization of U-101387, a dopamine D4 receptor selective antagonist.
abstract: Dopamine D2-like receptors play an important role in the pharmacotherapy of psychotic disorders. Molecular and cellular techniques have identified distinct gene products (D2-long, D2-short, D3 and D4) displaying the D2 receptor pharmacology. However, the contribution of each subtype in antipsychotic effects of or their physiological role remain unclear. Here we describe the pharmacological effects of a selective D4 antagonist, U-101387. U-101387 displayed moderately high affinity (Ki = 10 nM) and selectivity for the dopamine D4.2 receptor expressed in clonal cell lines. It lacked measurable affinity for not only other dopamine receptors but also noradrenalin, serotonin and histamine receptor families (Ki > 2000 nM). It fully and dose-dependently antagonized quinpirole-induced cAMP inhibition (without producing any effect by itself) in stably transfected cells. U-101387 also displayed excellent oral bioavailability, brain penetration and other pharmacokinetic characteristics. Unlike classical neuroleptics (e.g., haloperidol), U-101387 neither blocked acute behavioral effects of amphetamine or apomorphine nor did it alter spontaneous locomotion by itself. Additionally, U-101387 was without effect in behavioral and biochemical tests predictive of extrapyramidal and neuroendocrine side effects. Consistent with the lack of autoreceptor function of D4, acute administration of U-101387 failed to alter dopamine neuronal firing by itself or reverse the inhibition produced by dopamine agonists and to affect monoamine turnover in areas innervated by the mesencephalic or hypothalamic dopamine neurons. However, U-101387 potently induced c-fos mRNA expression in the infralimbic/ventral prelimbic cortex to a level similar to that produced by the atypical antipsychotic, clozapine. This is consistent with the predominantly cortical distribution of the D4 receptor. Taken together, these results demonstrate that the D4-selective antagonist, U-101387, produces effects that are distinct from those of the nonselective D2 antagonists as well as D3-preferring agents. U-101387 offers a unique tool to understand the role of dopamine D4 receptors in diseases involving central dopamine systems.
authors.affiliation: CNS Diseases Research, Pharmacia and Upjohn, Inc., Kalamazoo, Michigan, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Merchant
authors.forename: G S
authors.initials: GS
authors.lastname: Gill
authors.forename: D W
authors.initials: DW
authors.lastname: Harris
authors.forename: R M
authors.initials: RM
authors.lastname: Huff
authors.forename: M J
authors.initials: MJ
authors.lastname: Eaton
authors.forename: K
authors.initials: K
authors.lastname: Lookingland
authors.forename: B S
authors.initials: BS
authors.lastname: Lutzke
authors.forename: R B
authors.initials: RB
authors.lastname: Mccall
authors.forename: M F
authors.initials: MF
authors.lastname: Piercey
authors.forename: P J
authors.initials: PJ
authors.lastname: Schreur
authors.forename: V H
authors.initials: VH
authors.lastname: Sethy
authors.forename: M W
authors.initials: MW
authors.lastname: Smith
authors.forename: K A
authors.initials: KA
authors.lastname: Svensson
authors.forename: A H
authors.initials: AH
authors.lastname: Tang
authors.forename: P F
authors.initials: PF
authors.lastname: Vonvoigtlander
authors.forename: R E
authors.initials: RE
authors.lastname: Tenbrink
mesh_terms: D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001665:Binding Sites; D001682:Biological Availability; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D005786:Gene Expression Regulation / Q000187:drug effects; D016762:Genes, fos; D006801:Humans; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D050638:Receptors, Dopamine D4; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D012701:Serotonin / Q000378:metabolism; D013449:Sulfonamides / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D000096926:Benzenesulfonamides
chemical_list: D000662:Amphetamines; D001058:Apomorphine; D004298:Dopamine; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D010879:Piperazines; D012333:RNA, Messenger; D050638:Receptors, Dopamine D4; D011994:Recombinant Proteins; D012701:Serotonin; D013449:Sulfonamides; C493599:DRD4 protein, human; C493600:Drd4 protein, mouse; C493601:Drd4 protein, rat; C100448:sonepiprazole; D000096926:Benzenesulfonamides