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Titolo:
DIFFERENTIAL MANAGEMENT OF CA2-PITUITARY-CELLS - A COMPARATIVE OVERVIEW( OSCILLATIONS BY ANTERIOR)
Autore:
KWIECIEN R; HAMMOND C;
Indirizzi:
INSERM,U159,2 TER RUE ALESIA F-75014 PARIS FRANCE INSERM,U159 F-75014 PARIS FRANCE
Titolo Testata:
Neuroendocrinology
fascicolo: 3, volume: 68, anno: 1998,
pagine: 135 - 151
SICI:
0028-3835(1998)68:3<135:DMOC-A>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
THYROTROPIN-RELEASING-HORMONE; SECRETING ADENOMA CELLS; RAT LACTOTROPH CELLS; BROMOCRIPTINE-RESISTANT PROLACTINOMAS; ABNORMAL TRANSDUCTION MECHANISMS; DEPENDENT POTASSIUM CURRENTS; INDUCED CALCIUM OSCILLATIONS; ENRICHED PRIMARY CULTURES; PROTEIN-KINASE-C; GROWTH-HORMONE;
Keywords:
SOMATOTROPES; GROWTH HORMONE-RELEASING HORMONE; SOMATOSTATIN; LACTOTROPES; THYROTROPES; THYROTROPIN-RELEASING HORMONE; GONADOTROPES; GONADOTROPIN-RELEASING HORMONE; CORTICOTROPES; CORTICOTROPIN-RELEASING HORMONE; CATECHOLAMINES; PACEMAKER ACTIVITY; [CA2+](I) OSCILLATIONS; PITUITARY TUMORS; GH CELL LINES;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
106
Recensione:
Indirizzi per estratti:
Citazione:
R. Kwiecien e C. Hammond, "DIFFERENTIAL MANAGEMENT OF CA2-PITUITARY-CELLS - A COMPARATIVE OVERVIEW( OSCILLATIONS BY ANTERIOR)", Neuroendocrinology, 68(3), 1998, pp. 135-151

Abstract

Most electrical and ionic properties of anterior pituitary cells are common to all pituitary cell types; only gonadotropes exhibit a few cell specific features. Under basal conditions, the majority of pituitary cells in vitro, irrespective of their cell type, display spontaneousaction potentials and [Ca2+](i) transients that result from rhythmic Ca2+ entry through L-type Ca2+ channels. The main function of these action potentials is to maintain cells in a readily activable responsivestate. We propose to call this state a 'pacemaker mode', since it persists in the absence of extrinsic stimulation. When challenged by hypothalamic releasing hormones, cells exhibit two distinct response patterns: amplification of pacemaker activity or shift to internal Ca2+ release mode. In the internal Ca2+ release mode, [Ca2+](i) oscillations are not initiated by entry of external Ca2+, but by release of Ca2+ from intracellular stores. In somatotropes and corticotropes, GHRH or CRHtriggers the pacemaker mode in silent cells and amplifies it in spontaneously active cells. In contrast, in gonadotropes GnRH activates theinternal Ca2+ release mode in silent cells and switches already active cells from the pacemaker to the internal Ca2+ release mode. Interestingly, homologous normal and tumoral cells display the same type of activity in vitro, in the absence or presence of hypothalamic hormones. Pacemaker and internal Ca2+ release modes are likely to serve different purposes. Pacemaker activity allows along-lasting sequences of [Ca2+](i) oscillations (and thus sustained periods of secretion) that stop under the influence of hypothalamic inhibitory peptides. In contrast, the time during which cells can maintain internal Ca2+ release mode depends upon the importance of intracellular Ca2+ stores. This modes is thus more adapted to trigger secretory peaks of large amplitude and short duration. On the basis of these observations, theoretical models of pituitary cell activity can be proposed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 17/01/20 alle ore 20:09:13