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Titolo:
Resolution of two [S-35]GTP-gamma-S binding sites and their response to chronic morphine treatment: A binding surface analysis
Autore:
Heyliger, SO; Ni, Q; Rothman, RB;
Indirizzi:
Natl Inst Drug Abuse, Clin Psychopharmacol Sect, Intramural Res Program, NIH, Baltimore, MD 21224 USA Natl Inst Drug Abuse Baltimore MD USA 21224 NIH, Baltimore, MD 21224 USA
Titolo Testata:
BRAIN RESEARCH BULLETIN
fascicolo: 4, volume: 51, anno: 2000,
pagine: 357 - 362
SICI:
0361-9230(20000301)51:4<357:ROT[BS>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
MU-OPIOID RECEPTOR; NEUROBLASTOMA SH-SY5Y CELLS; GUINEA-PIG BRAIN; G-PROTEINS; RAT-BRAIN; INDUCED DESENSITIZATION; DOWN-REGULATION; HIGH-AFFINITY; TOLERANCE; ACTIVATION;
Keywords:
opioid receptors; G-proteins; tolerance; dependence;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Rothman, RB Natl Inst Drug Abuse, Clin Psychopharmacol Sect, Intramural Res Program, NIH, POB 5180,5500 Nathan Shock Dr, Baltimore, MD 21224 USA NatlInst Drug Abuse POB 5180,5500 Nathan Shock Dr Baltimore MD USA 21224
Citazione:
S.O. Heyliger et al., "Resolution of two [S-35]GTP-gamma-S binding sites and their response to chronic morphine treatment: A binding surface analysis", BRAIN RES B, 51(4), 2000, pp. 357-362

Abstract

The mechanisms by which prolonged exposure to morphine leads to tolerance are not fully understood. We investigated the effects of etorphine (ET) on [S-35]guanosine 5'-(thio)-triphosphate ([S-35]GTP-gamma-S) binding in brains of rats made tolerant to morphine via the implantation of morphine (or placebo) pellets. Binding surface analysis was used to characterize the interactions of ET, Gpp(Np)H and GTP-gamma-S with sites labeled by [S-35]GTP-gamma-S. Data sets were fitted to one- and two-site binding models using the nonlinear least squares curve fitting program MLAB-PC (Civilized Software, Bethesda, MD, USA). Two binding sites were readily resolved. Chronic morphine significantly increased the B-max and K-d of the high affinity binding site, ET stimulated [S-35]GTP-gamma-S binding in placebo membranes via an increase in the B-max of the high affinity binding site. In contrast, ET stimulated [S-35]GTP-gamma-S in chronic morphine membranes via a large decrease in the K-d of the high affinity site. These results suggest that chronic morphine treatment alters the mechanism by which ET stimulates [S-35]GTP-gamma-S binding to G-proteins. Since proper G-protein/receptor coupling increases [S-35]GTP-gamma-S binding via an increase in B-max values, these resultssuggest that opioid receptors in chronic morphine membranes are not normally coupled to G-proteins. These findings corroborate earlier studies that reported changes in G-protein function in morphine tolerant animals. published by Elsevier Science Inc.

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Documento generato il 29/03/20 alle ore 13:07:56