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Titolo:
MULTIPLE HYPOTHALAMIC FACTORS REGULATE PYROGLUTAMYL PEPTIDASE-II IN CULTURES OF ADENOHYPOPHYSEAL CELLS - ROLE OF THE CAMP PATHWAY
Autore:
VARGAS MA; BOURDAIS J; SANCHEZ S; URIOSTEGUI B; MORENO E; JOSEPHBRAVO P; CHARLI JL;
Indirizzi:
UNIV NACL AUTONOMA MEXICO,INST BIOTECNOL,AP 510-3 CUERNAVACA 62271 MORELOS MEXICO UNIV NACL AUTONOMA MEXICO,INST BIOTECNOL CUERNAVACA 62271 MORELOS MEXICO
Titolo Testata:
Journal of neuroendocrinology
fascicolo: 3, volume: 10, anno: 1998,
pagine: 199 - 206
SICI:
0953-8194(1998)10:3<199:MHFRPP>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
THYROTROPIN-RELEASING-HORMONE; TRH-DEGRADING ENZYME; RAT LACTOTROPH CELLS; DUAL 2ND MESSENGERS; THYROID-HORMONES; PROLACTIN SECRETION; ANTERIOR-PITUITARY; PHORBOL ESTERS; BRAIN; RECEPTORS;
Keywords:
TRH; PYROGLUTAMYL PEPTIDASE II; LACTOTROPH; DOPAMINE; DEGRADATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
M.A. Vargas et al., "MULTIPLE HYPOTHALAMIC FACTORS REGULATE PYROGLUTAMYL PEPTIDASE-II IN CULTURES OF ADENOHYPOPHYSEAL CELLS - ROLE OF THE CAMP PATHWAY", Journal of neuroendocrinology, 10(3), 1998, pp. 199-206

Abstract

In the adenohypophysis, thyrotrophin-releasing hormone (TRH) is inactivated by pyroglutamyl peptidase II (PPII), a TRH-specific ectoenzyme localized in lactotrophs. TRH slowly downregulates surface PPII activity in adenohypophyseal cell cultures. Protein kinase C (PKC) activation mimics this effect. We tested the hypothesis that other hypothalamicfactors controlling prolactin secretion could also regulate PPII activity in adenohypophyseal cell cultures. incubation for 16 h with pituitary adenylate cyclase activator peptide 38 (PACAP; 10(-6) M) decreased PPII activity. Bromocryptine (10(-8) M), a D2 dopamine receptor agonist, or somatostatin (10(-6) M) stimulated enzyme activity and blockedthe inhibitory effect of [3-Me-His(2)]-TRH, a TRH receptor agonist. Bromocryptine and somatostatin actions were suppressed by preincubationwith pertussis toxin (400 ng ml(-1)). Because these hypophysiotropic factors transduce some of their effects using the cAMP pathway, we analysed its role on PPII regulation. Cholera toxin (400 ng ml(-1)) inhibited PPII activity. Forskolin (10(-6) M) caused a time-dependent decrease in PPII activity, with maximal inhibition at 12-16 h treatment; ED50 was 10(-7) M. 3-isobutyl-1-methylxanthine or dibutiryl cAMP, causeda dose-dependent inhibition of PPII activity. These data suggest thatincreased cAMP down-regulates PPII activity. The effect of PACAP was blocked by preincubation with H89 (10(-6) M), a protein kinase A inhibitor, suggesting that the cAMP pathway mediates some of the effects ofPACAP. Maximal effects of forskolin and 12-O-tetradecanoylphorbol 13-acetate were additive. PPII activity, therefore, is independently regulated by the cAMP and PKC pathways. Because most treatments inhibited PPII mRNA levels similarly to PPII activity, an important level of control of PPII activity by these factors may be at the mRNA level. We suggest that PPII is subject to 'homologous' and 'heterologous' regulation by elements of the multifactorial system that controls prolactin secretion.

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Documento generato il 27/01/20 alle ore 17:00:23