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Titolo:
D2 DOPAMINERGIC RECEPTORS - NORMAL AND ABNORMAL TRANSDUCTION MECHANISMS
Autore:
CACCAVELLI L; CUSSAC D; PELLEGRINI I; AUDINOT V; JAQUET P; ENJALBERT A;
Indirizzi:
CTR PAUL BROCA,INSERM,U159,2 RUE DALESIA F-75014 PARIS FRANCE CTR PAUL BROCA,INSERM,U159,2 RUE DALESIA F-75014 PARIS FRANCE UER MED NORD,INSERM,U297 MARSEILLE FRANCE
Titolo Testata:
Hormone research
fascicolo: 1-2, volume: 38, anno: 1992,
pagine: 78 - 83
SICI:
0301-0163(1992)38:1-2<78:DDR-NA>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
ANTERIOR-PITUITARY-CELLS; RAT LACTOTROPH CELLS; INOSITOL PHOSPHATE PRODUCTION; THYROTROPIN-RELEASING-HORMONE; ADENYLATE-CYCLASE; PROLACTIN-RELEASE; G-PROTEINS; D2-DOPAMINE RECEPTOR; BINDING-PROTEIN; PHOSPHOLIPASE-C;
Keywords:
D2 DOPAMINE RECEPTORS; G-PROTEINS; PROLACTINOMAS; PLA2; PLC;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
54
Recensione:
Indirizzi per estratti:
Citazione:
L. Caccavelli et al., "D2 DOPAMINERGIC RECEPTORS - NORMAL AND ABNORMAL TRANSDUCTION MECHANISMS", Hormone research, 38(1-2), 1992, pp. 78-83

Abstract

Dopamine receptors of D2 type present on lactotroph cells are coupledto a large series of transduction mechanisms. Beside their negative coupling with adenylate cyclase, they are also coupled with potassium and calcium channels. leading to a decreased intracellular calcium concentration. In addition, D2 dopamine receptors also modulate phospholipase activities. Dopamine inhibits inositol phosphate production, through two distinct mechanisms. One of them could represent a direct negative coupling with phospholipase C. All these transduction mechanisms of the D2 dopamine receptors implicate G proteins sensitive to pertussis toxin. In contrast, these receptors are negatively coupled to phospholipase A2 through G proteins insensitive to this toxin. Both isoformsof the D2 dopamine receptor, generated by alternate splicing of a single gene, are present in lactotroph cells. After transfection in CH4C1cells the two isoforms are coupled with adenylate cyclase while only the shortest isoform appears negatively coupled to phospholipase C. Functional D2 dopamine receptors are present in human prolactinomas. Resistance to bromocriptine therapy is associated with a decreased density of these receptors in the tumor. In addition, the ratio of the two receptor isoforms (measured by PCR) is different in responsive and resistant tumors. Furthermore, the activity of Gi/Go proteins coupled to adenylate cyclase appears also affected in resistant tumors. Resistanceto bromocriptine therapy appears thus to involve multiple changes at the different levels of the multiple mechanisms of action of dopamine on lactotroph cells.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/02/20 alle ore 14:56:47