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Titolo:
MECHANISM OF ACTION OF HEXARELIN .1. GROWTH HORMONE-RELEASING ACTIVITY IN THE RAT
Autore:
TORSELLO A; GRILLI R; LUONI M; GUIDI M; GHIGO MC; WEHRENBERG WB; DEGHENGHI R; MULLER EE; LOCATELLI V;
Indirizzi:
UNIV MILAN,DEPT PHARMACOL,SCH MED,VIA VANVITELLI 32 I-20129 MILAN ITALY UNIV WISCONSIN,DEPT HLTH SCI & BIOL SCI MILWAUKEE WI 53201 EUROPEPTIDES GEIE ARGENTEUIL FRANCE
Titolo Testata:
European journal of endocrinology
fascicolo: 4, volume: 135, anno: 1996,
pagine: 481 - 488
SICI:
0804-4643(1996)135:4<481:MOAOH.>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
PITUITARY-CELLS; GH SECRETION; ADENOSINE-3',5'-MONOPHOSPHATE ACCUMULATION; SOMATOTROPIC FUNCTION; ANTERIOR-PITUITARY; INFANT RATS; HEXAPEPTIDE; PEPTIDE; INVITRO; HIS-D-TRP-ALA-TRP-D-PHE-LYS-NH2;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
38
Recensione:
Indirizzi per estratti:
Citazione:
A. Torsello et al., "MECHANISM OF ACTION OF HEXARELIN .1. GROWTH HORMONE-RELEASING ACTIVITY IN THE RAT", European journal of endocrinology, 135(4), 1996, pp. 481-488

Abstract

We have reported Hexarelin (HEXA), an analog of growth hormone-releasing peptide 6 (GHRP-6), potently stimulates growth hormone (GH) secretion in infant and adult rats. This study was undertaken to further investigate Hexarelin's mechanisms of action. In 10-day-old pups, treatments with HEXA (80 mu g/kg, b.i.d.) for 3-10 days significantly enhanced, in a time-related fashion, the GH response to an acute HEXA challenge. Qualitatively similar effects were elicited in pups passively immunized against growth hormone-releasing hormone (GHRH) from birth. In adult male rats, a 5-day pretreatment with HEXA (150 mu g/kg, b.i.d.) did not enhance the effect of the acute challenge, and the same patternwas present after a 5-day pretreatment in male rats with surgical ablation of the mediobasal hypothalamus (MBH-ablated rats). In addition, in adult sham-operated rats, Hexarelin (300 mu g/kg, iv) induced a GH response greater (p < 0.05) than that induced by GHRH (2 mu g/kg, iv). However, in MBH-ablated rats 7 days after surgery, GHRH was significantly (p < 0.05) more effective than HEXA, and 30 days after surgery HEXA and GHRH evoked similar rises of plasma GH. Finally, the in vitro Hexarelin (10(-6) mol/l) effect was transient while GHRH (10(-8) mol/l)induced a longer lasting and greater GH release. Three different mechanisms, not mutually exclusive, are postulated for Hexarelin stimulation of GH secretion in vivo: a direct action on the pituitary, though of minor relevance; an indirect action that involves release of GHRH, of relevance only in adult rats; and an action through the release of astill unknown hypothalamic ''factor'', which in infant and adult ratselicits GH release acting sinergistically with GHRH.

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Documento generato il 01/10/20 alle ore 04:28:57