title: Antipsychotics differ in their ability to internalise human dopamine D2S and human serotonin 5-HT1A receptors in HEK293 cells.
abstract: Antipsychotic drugs act preferentially via dopamine D(2) receptor blockade, but interaction with serotonin 5-HT(1A) receptors has attracted interest as additional target for antipsychotic treatment. As receptor internalisation is considered crucial for drug action, we tested the propensity of antipsychotics to internalise human (h)D(2S) receptors and h5-HT(1A) receptors. Agonist-induced internalisation of hemaglutinin (HA)-tagged hD(2S) and HA-h5-HT(1A) receptors expressed in HEK293 cells was increased by coexpression of G-protein coupled receptor kinase 2 and beta-arrestin2. At the HA-hD(2S) receptor, dopamine, quinpirole and bromocriptine behaved as full agonists, while S(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [(-)-3PPP] and sarizotan were partial agonists. The typical antipsychotic, haloperidol, and the atypical compounds, olanzapine, nemonapride, ziprasidone and clozapine did not internalise HA-hD(2S) receptors, whereas aripiprazole potently internalised these receptors (>50% relative efficacy). Among antipsychotics with combined D(2)/5-HT(1A) properties, bifeprunox and (3-exo)-8-benzoyl-N-[[(2S)7-chloro-2,3-dihydro-1,4-benzodioxin-1-yl]methyl]-8-azabicyclo-[3.2.1]octane-3-methanamine (SSR181507) partially internalised HA-hD(2S) receptors, piperazine, 1-(2,3-dihydro-1,4-benzodioxin-5-yl)-4-[[5-(4-fluorophenyl)-3-pyridinyl]methyl (SLV313) and N-[(2,2-dimethyl-2,3-dihydro-benzofuran-7-yloxy)ethyl]-3-(cyclopent-1-enyl)-benzylamine (F15063) were inactive. At the HA-h5-HT(1A) receptor, serotonin, (+)-8-hydroxy-2-(di-n-propylamino)tetralin [(+)-8-OH-DPAT] and sarizotan were full agonists, buspirone acted as partial agonist. (-)-Pindolol showed little activity and no internalising properties were manifested for the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]-ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY100635). Most antipsychotics induced HA-h5-HT(1A) receptor internalisation, with an efficacy rank order: nemonapride>F15063>SSR181507>bifeprunox approximately SLV313 approximately ziprasidone>aripiprazole and potencies: SLV313>SSR181507 approximately F15063>bifeprunox approximately nemonapride approximately aripiprazole>ziprasidone. Interestingly, the internalisation induced by clozapine was only minimal, whereas aripirazole and bifeprunox were more potent for internalisation than for G-protein activation. These different profiles of antipsychotics for receptor internalisation may help to evaluate their potential therapeutic impact in the treatment of schizophrenia.
authors.affiliation: Cellular and Molecular Biology Department, Pierre Fabre Research Center, F-81106 Castres, France. peter.heusler@pierre-fabre.com
authors.forename: Peter
authors.initials: P
authors.lastname: Heusler
authors.forename: Adrian
authors.initials: A
authors.lastname: Newman-Tancredi
authors.forename: Timothé
authors.initials: T
authors.lastname: Loock
authors.forename: Didier
authors.initials: D
authors.lastname: Cussac
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D014150:Antipsychotic Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D019257:Quinpirole / Q000494:pharmacology; D044282:Receptor, Serotonin, 5-HT1A / Q000187:drug effects* / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000187:drug effects* / Q000378:metabolism
chemical_list: D014150:Antipsychotic Agents; D017448:Receptors, Dopamine D2; C113776:dopamine D2L receptor; D044282:Receptor, Serotonin, 5-HT1A; D019257:Quinpirole; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D017371:8-Hydroxy-2-(di-n-propylamino)tetralin