DOPAMINERGIC SYSTEMS : Dopamine Receptors - 11/09/11
Résumé |
Historically, dopamine (DA) receptors have been divided into two major subtypes referred to as D1 and D2, which differ in (1) their coupling to G-proteins, (2) their distribution within the central nervous system (CNS), and (3) their pharmacology. D1 receptors activate the enzyme adenyl cyclase, and increase intracellular levels of cAMP, whereas D2 receptors exert an inhibitory influence on this enzyme; D2 receptors also may be linked to additional second-messenger systems, including activation of K+ channels, inhibition of Ca2+ channels, and phosphatidylinositol turnover. The cloning of these receptors and their genes in the last decade and the subsequent identification of multiple DA receptors referred to as D1, D2, D3, D4, and D5 have profoundly changed our understanding of the anatomy and pharmacology of DA receptors. Two of these cloned receptors exhibit the functional and pharmacologic properties of classic D1 receptors, whereas the other three present the pharmacologic characteristics of D2 receptors. Thus, it is now recognized that subfamilies of D1 and D2 receptors exist rather than single receptor subtypes. Indeed, as can be seen in Table 1, DA elicits both similar and distinct responses compared with D1-like (D1 and D5) and D2-like (D2, D3, and D4) receptors in fibroblast cells, expressing the recombinant receptors.
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Address reprint requests to João Palermo-Neto, MS, PhD, Faculdade de Medicina Veterinária USP, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP, Brazil 05508–900 |
Vol 20 - N° 4
P. 705-721 - décembre 1997 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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