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Titolo:
Cloning, expression, functional coupling and pharmacological characterization of the rat dopamine D-4 receptor
Autore:
Gazi, L; Schoeffter, P; Nunn, C; Croskery, K; Hoyer, D; Feuerbach, D;
Indirizzi:
Novartis Pharma AG, Nervous Syst Res, CH-4002 Basel, Switzerland Novartis Pharma AG Basel Switzerland CH-4002 CH-4002 Basel, Switzerland
Titolo Testata:
NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY
fascicolo: 5, volume: 361, anno: 2000,
pagine: 555 - 564
SICI:
0028-1298(200005)361:5<555:CEFCAP>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
HAMSTER OVARY CELLS; GAMMA-S BINDING; ANTIPSYCHOTIC AGENTS; HIGH-AFFINITY; HEK293 CELLS; SCHIZOPHRENIA; LINES; AGONIST; KINASE; GENE;
Keywords:
dopamine; signal transduction; rat brain; rat dopamine D-4 receptor; cAMP; extracellular acidification; [S-35]GTP gamma S;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Feuerbach, D Novartis Pharma AG, Nervous Syst Res, CH-4002 Basel, Switzerland Novartis Pharma AG Basel Switzerland CH-4002 l, Switzerland
Citazione:
L. Gazi et al., "Cloning, expression, functional coupling and pharmacological characterization of the rat dopamine D-4 receptor", N-S ARCH PH, 361(5), 2000, pp. 555-564

Abstract

It has been difficult to observe functional coupling of the D-4 receptor to second messenger systems and a robust functional assay system for this receptor is still lacking. In the present study, the rat dopamine D, receptorwas cloned from rat retina. Sequence comparison revealed identity with thepublished sequence of Ashgari and coworkers, including the two amino acid insertions (V-Q) at position 92 which are not present in the published sequence of O'Malley and coworkers. The rat dopamine D, receptor was stably expressed in Chinese hamster lung fibroblast CCL39 cells. [H-3]spiperone saturation binding yielded a B-max of 2370+/-546 fmol/mg protein and a pK(D) of 8.74+/-0.14 (n=4). Forskolin-stimulated cAMP accumulation was inhibited by dopamine (E-max 61+/-1% inhibition of forskolin-stimulated levels, pEC(50),7.33+/-0.06, n=23). A similar concentration-dependent inhibition was observed with the dopamine D-2-like receptor agonists quinpirole and 7-OH-DPAT which elicited nearly the same E-max as dopamine. By contrast, apomorphine and a number of compounds with reported affinity for human dopamine D-4 receptors (PD168077, U-101958, SDZ GLC 756, L-745,870 and NGD 94-1) behaved as partial agonists (E-max ranging between 26% and 56% of that of dopamine). The agonist effect of dopamine was completely blocked by preincubation with pertussis toxin, no further accumulation of cAMP above the forskolin-stimulated levels being observed. Antagonist pK(B)-values obtained against dopamine in this system were: 8.55+/-0.19 (n=3) for the partial agonist L-745,870, 8.38+/-0.23 (n=5) for spiperone, 7.18+/-0.17 (n=4) for haloperidol, 7.04+/-0.13 (n=4) for clozapine and <6 for raclopride. Other functional assays applicable were stimulation of [S-35]GTP gamma S binding, extracellular acidification rate and a serum-responsive element using luciferase expression as a reporter gene. However, the receptor did not couple to phosphatidylinositol turnover or to intracellular Ca2+. Thus, expression of the rat dopamine D-4 receptor in CCL39 cells provided several functional assay systems, ofwhich inhibition of cAMP appeared to be the most robust one. These functional models can be used to evaluate the activity of compounds at the rat dopamine D-4 receptor.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 07:43:55