The growth hormone-releasing hexapeptide (GHRP-6) specifically stimulates growth hormone (GH) secretion in several animal species and humans. The mechanism of action of GHRP-6 is largely unknown, although experimental evidence indicates that it may modulate growth hormone-releasing hormone (GHRH) and somatostatin actions at the pituitary or hypothalamic level. To gain more insight into the mechanism(s) of action of GHRP-6, we studied the infant rat, an animal model highly responsive to GH-releasing stimuli. In 14-d-old rats GHRP-6 (32-600 micrograms/kg, s.c.) induced a marked and dose-dependent rise in plasma GH concentrations, maximal stimulation occurring with the dose of 300 micrograms/kg. Neither GHRH nor somatostatin antiserum prevented or modified the GH release elicited by GHRP-6. In pups passively immunized with GHRH antibodies, a 5-d treatment with GHRP-6 (80 micrograms/kg, s.c., twice daily) completely counteracted the inhibitory effect of GHRH deprivation on GH mRNA expression. In vitro GHRP-6 (10(-7) and 10(-6) M) induced a small and transient stimulation of GH release from cultured pituitary cells. These results indicate the following: 1) GHRP-6 is a potent stimulator of GH release in rat pups; 2) it stimulates GH gene expression in the GHRH-deprived pup; 3) during the neonatal period its action is not mediated by GHRH or somatostatin; and 4) its actions are not directed at the somatotrophs.

Locatelli, V., Grilli, R., Torsello, A., Cella, S., Wehrenberg, W., & Müller, E. (1994). Growth hormone-releasing hexapeptide is a potent stimulator of growth hormone gene expression and release in the growth hormone-releasing hormone-deprived infant rat. PEDIATRIC RESEARCH, 36(2), 169-174 [10.1203/00006450-199408000-00006].

Growth hormone-releasing hexapeptide is a potent stimulator of growth hormone gene expression and release in the growth hormone-releasing hormone-deprived infant rat

LOCATELLI, VITTORIO;TORSELLO, ANTONIO BIAGIO;
1994-08

Abstract

The growth hormone-releasing hexapeptide (GHRP-6) specifically stimulates growth hormone (GH) secretion in several animal species and humans. The mechanism of action of GHRP-6 is largely unknown, although experimental evidence indicates that it may modulate growth hormone-releasing hormone (GHRH) and somatostatin actions at the pituitary or hypothalamic level. To gain more insight into the mechanism(s) of action of GHRP-6, we studied the infant rat, an animal model highly responsive to GH-releasing stimuli. In 14-d-old rats GHRP-6 (32-600 micrograms/kg, s.c.) induced a marked and dose-dependent rise in plasma GH concentrations, maximal stimulation occurring with the dose of 300 micrograms/kg. Neither GHRH nor somatostatin antiserum prevented or modified the GH release elicited by GHRP-6. In pups passively immunized with GHRH antibodies, a 5-d treatment with GHRP-6 (80 micrograms/kg, s.c., twice daily) completely counteracted the inhibitory effect of GHRH deprivation on GH mRNA expression. In vitro GHRP-6 (10(-7) and 10(-6) M) induced a small and transient stimulation of GH release from cultured pituitary cells. These results indicate the following: 1) GHRP-6 is a potent stimulator of GH release in rat pups; 2) it stimulates GH gene expression in the GHRH-deprived pup; 3) during the neonatal period its action is not mediated by GHRH or somatostatin; and 4) its actions are not directed at the somatotrophs.
Articolo in rivista - Articolo scientifico
Scientifica
Rats; RNA, Messenger; Animals; Rats, Sprague-Dawley; Pituitary Gland; Immunization, Passive; Gene Expression; Oligopeptides; Growth Hormone-Releasing Hormone; Male; Female; Growth Hormone
English
Locatelli, V., Grilli, R., Torsello, A., Cella, S., Wehrenberg, W., & Müller, E. (1994). Growth hormone-releasing hexapeptide is a potent stimulator of growth hormone gene expression and release in the growth hormone-releasing hormone-deprived infant rat. PEDIATRIC RESEARCH, 36(2), 169-174 [10.1203/00006450-199408000-00006].
Locatelli, V; Grilli, R; Torsello, A; Cella, S; Wehrenberg, W; Müller, E
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10281/37151
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