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Titolo:
A TEMPORALLY INTERMEDIATE-MODE OF GONADOTROPIN-RELEASING HORMONE-INDUCED DESENSITIZATION OF LUTEINIZING-HORMONE SECRETION
Autore:
CASSINA MP; GRANTHAM KD; NEILL JD;
Indirizzi:
UNIV ALABAMA,SCH MED,DEPT PHYSIOL & BIOPHYS,BHSB 812,1918 UNIV BLVD BIRMINGHAM AL 35294 UNIV ALABAMA,SCH MED,DEPT PHYSIOL & BIOPHYS BIRMINGHAM AL 35294 UNIV ALABAMA,SCH DENT,DEPT PHYSIOL & BIOPHYS BIRMINGHAM BHSB 812 W MIDLANDS ENGLAND
Titolo Testata:
Molecular and cellular endocrinology
fascicolo: 1-2, volume: 132, anno: 1997,
pagine: 53 - 59
SICI:
0303-7207(1997)132:1-2<53:ATIOGH>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
STIMULATED PITUITARY GONADOTROPHS; HOMOLOGOUS DOWN-REGULATION; RAT ESTROUS-CYCLE; RAPID DESENSITIZATION; LH-RELEASE; RECEPTOR; CELLS; GNRH; RESPONSIVENESS; ALPHA-T3-1;
Keywords:
GONADOTROPIN RELEASING HORMONE; LUTEINIZING HORMONE; DESENSITIZATION; PITUITARY (GONADOTROPE);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
M.P. Cassina et al., "A TEMPORALLY INTERMEDIATE-MODE OF GONADOTROPIN-RELEASING HORMONE-INDUCED DESENSITIZATION OF LUTEINIZING-HORMONE SECRETION", Molecular and cellular endocrinology, 132(1-2), 1997, pp. 53-59

Abstract

The classical mode of luteinizing hormone (LH) secretory desensitization in the rat appears after 3-6 h of continuous in vitro administration of gonadotropin (GnRH). A second mode has been reported to occur very rapidly (<2 min) after the onset of GnRH administration, and to reverse within 3 min after its withdrawal. Here, the existence of a thirdmode of desensitization is reported, occurring at 40-50 min after initiation of continuous GnRH administration. Rat pituitary cells were perifused with 10(-8) M GnRH for 6 h; 10 min samples were collected for LH measurements by radioimmunoassay. As expected, the pattern of LH release was biphasic: LH levels peaked in the first phase at 30 min, decreased at 40-50 min, increased in the second phase to maximal levels at 90-110 min, and then decreased in the classical desensitization modeto near-baseline values by 300-360 min. Static incubations of pituitary cells in Petri dishes in the presence of high (10(-8) M) or submaximal (10(-9) M) GnRH concentrations confirmed the decrease in LH secretion at 40-50 min. Measurement of LH by reverse hemolytic plaque assay (RHPA) confirmed the existence of this new mode of desensitization; since 93% of all gonadotropes had become secretory at 40-50 min, the possibility of two subpopulations of gonadotropes accounting for the two phases of LH secretion appears to be ruled-out. GnRH receptor binding studies demonstrated a similar to 50% decrease in cell-surface bindingin association with the desensitization at 40-50 min. These studies suggest the existence of a third mode of GnRH-induced LH secretory desensitization that is not due to gonadotrope subpopulations but may be causally associated with decreased GnRH receptor binding. (C) 1997 Elsevier Science Ireland Ltd.

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Documento generato il 20/09/20 alle ore 23:43:09