title: Dopamine D2-D3 receptor heteromers: pharmacological properties and therapeutic significance.
abstract: Heteromerization of dopamine receptors has been shown for both the D(1)/D(5) and D(2)/D(3)/D(4) receptor families, which couple positively and negatively, respectively, to adenylyl cyclase. The present article reviews data on dopamine heteromers formed by D(3), focusing in particular on associations with their D(2) counterparts. Certain antiparkinsonian agents, like the preferential and high efficacy D(3)>D(2) agonists, pramipexole, and ropinirole, show amplified potency at D(2)-D(3) heteromers versus constituent monomers. Accordingly, in cells cotransfected with D(2) and D(3) receptors, pramipexole, and ropinirole suppress forskolin (FK)-stimulated cAMP production with higher potencies as compared to cells transfected with D(2) or D(3) receptors only. Furthermore, in cells cotransfected with D(2) and an excess of D(3) receptors, the partial agonists aripiprazole, S33592, bifeprunox, N-desmethylclozapine, and preclamol lose agonist properties and abolish the actions of quinpirole. Then, partial agonists are transformed into antagonists upon cotransfection of D(2) with an excess of D(3) receptors. A hypothetical relationship of the above observations to the pathophysiology and possibly treatment of neuropsychiatric diseases is discussed.
authors.affiliation: Department of Experimental Medicine, University of L'Aquila, L'Aquila, Italy. roberto.maggio@univaq.it
authors.forename: Roberto
authors.initials: R
authors.lastname: Maggio
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Millan
mesh_terms: D000818:Animals; D015226:Dinucleoside Phosphates / Q000378:metabolism; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D006801:Humans; D001523:Mental Disorders / Q000188:drug therapy / Q000503:physiopathology; D009422:Nervous System Diseases / Q000188:drug therapy / Q000503:physiopathology; D055503:Protein Multimerization; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D050637:Receptors, Dopamine D3 / Q000187:drug effects / Q000378:metabolism*
chemical_list: D015226:Dinucleoside Phosphates; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; C013797:adenylyl cytidine