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The GH-releasing effect of ghrelin, a natural GH secretagogue, is only blunted by the infusion of exogenous somatostatin in humans.
Clin Endocrinol (Oxf). 2002 May; 56(5):643-8.CE

Abstract

OBJECTIVE

Ghrelin, a 28-amino-acid peptide purified from the stomach and showing a unique structure with an n-octanoyl ester at the serine 3 residue, is a natural ligand of the GH secretagogue (GHS) receptor (GHS-R). Ghrelin strongly stimulates GH secretion in both animals and humans, showing a synergistic effect with GH-releasing hormone (GHRH) but no interaction with synthetic GHS. However, the activity of ghrelin as well as that of non-natural GHS is not fully specific for GH; ghrelin also induces a stimulatory effect on lactotroph and corticotroph secretion, at least in humans.

DESIGN

To further clarify the mechanisms underlying the GH-releasing activity of this natural GHS, we studied the effects of somatostatin (SS, 2.0 microg/kg/h from -30 to +90 min) on the endocrine responses to ghrelin (1.0 microg/kg i.v. at 0 min) in seven normal young male volunteers [age (mean +/- SEM) 28.6 +/- 2.9 years; body mass index (BMI) 22.1 +/- 0.8 kg/m2]. In the same subjects, the effect of SS on the GH response to GHRH (1.0 microm/kg i.v. at 0 min) was also studied.

MEASUREMENTS

Blood samples were taken every 15 min from -30 up to +120 min. GH levels were assayed at each time point in all sessions; PRL, ACTH and cortisol levels were assayed after ghrelin administration alone and during SS infusion.

RESULTS

The GH response to ghrelin (hAUC0'-->120' 2695.0 +/- 492.6 microg min/l) was higher (P < 0.01) than that after GHRH (757.1 +/- 44.1 microg min/l). SS infusion almost abolished the GH response to GHRH (177.0 +/- 37.7 microg min/l, P < 0.01); the GH response to ghrelin was inhibited by SS (993.8 +/- 248.5 microg min/l, P < 0.01) but GH levels remained higher (P < 0.05) than with GHRH. Ghrelin induced significant increases in PRL, ACTH and cortisol levels and these responses were not modified by SS.

CONCLUSIONS

Ghrelin, a natural GHS-R ligand, exerts a strong stimulatory effect on GH secretion in humans and this effect is only blunted by an exogenous somatostatin dose which almost abolishes the GH response to GHRH. The stimulatory effect of ghrelin on lactotroph and corticotroph secretion is refractory to exogenous somatostatin, indicating that these effects occur through pathways independent of somatostatinergic influence.

Authors+Show Affiliations

Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Santiago de Compostela, Spain.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12030916

Citation

Di Vito, Lidia, et al. "The GH-releasing Effect of Ghrelin, a Natural GH Secretagogue, Is Only Blunted By the Infusion of Exogenous Somatostatin in Humans." Clinical Endocrinology, vol. 56, no. 5, 2002, pp. 643-8.
Di Vito L, Broglio F, Benso A, et al. The GH-releasing effect of ghrelin, a natural GH secretagogue, is only blunted by the infusion of exogenous somatostatin in humans. Clin Endocrinol (Oxf). 2002;56(5):643-8.
Di Vito, L., Broglio, F., Benso, A., Gottero, C., Prodam, F., Papotti, M., Muccioli, G., Dieguez, C., Casanueva, F. F., Deghenghi, R., Ghigo, E., & Arvat, E. (2002). The GH-releasing effect of ghrelin, a natural GH secretagogue, is only blunted by the infusion of exogenous somatostatin in humans. Clinical Endocrinology, 56(5), 643-8.
Di Vito L, et al. The GH-releasing Effect of Ghrelin, a Natural GH Secretagogue, Is Only Blunted By the Infusion of Exogenous Somatostatin in Humans. Clin Endocrinol (Oxf). 2002;56(5):643-8. PubMed PMID: 12030916.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The GH-releasing effect of ghrelin, a natural GH secretagogue, is only blunted by the infusion of exogenous somatostatin in humans. AU - Di Vito,Lidia, AU - Broglio,Fabio, AU - Benso,Andrea, AU - Gottero,Cristina, AU - Prodam,Flavia, AU - Papotti,Mauro, AU - Muccioli,Giampiero, AU - Dieguez,Carlos, AU - Casanueva,Felipe F, AU - Deghenghi,Romano, AU - Ghigo,Ezio, AU - Arvat,Emanuela, PY - 2002/5/29/pubmed PY - 2002/7/18/medline PY - 2002/5/29/entrez SP - 643 EP - 8 JF - Clinical endocrinology JO - Clin. Endocrinol. (Oxf) VL - 56 IS - 5 N2 - OBJECTIVE: Ghrelin, a 28-amino-acid peptide purified from the stomach and showing a unique structure with an n-octanoyl ester at the serine 3 residue, is a natural ligand of the GH secretagogue (GHS) receptor (GHS-R). Ghrelin strongly stimulates GH secretion in both animals and humans, showing a synergistic effect with GH-releasing hormone (GHRH) but no interaction with synthetic GHS. However, the activity of ghrelin as well as that of non-natural GHS is not fully specific for GH; ghrelin also induces a stimulatory effect on lactotroph and corticotroph secretion, at least in humans. DESIGN: To further clarify the mechanisms underlying the GH-releasing activity of this natural GHS, we studied the effects of somatostatin (SS, 2.0 microg/kg/h from -30 to +90 min) on the endocrine responses to ghrelin (1.0 microg/kg i.v. at 0 min) in seven normal young male volunteers [age (mean +/- SEM) 28.6 +/- 2.9 years; body mass index (BMI) 22.1 +/- 0.8 kg/m2]. In the same subjects, the effect of SS on the GH response to GHRH (1.0 microm/kg i.v. at 0 min) was also studied. MEASUREMENTS: Blood samples were taken every 15 min from -30 up to +120 min. GH levels were assayed at each time point in all sessions; PRL, ACTH and cortisol levels were assayed after ghrelin administration alone and during SS infusion. RESULTS: The GH response to ghrelin (hAUC0'-->120' 2695.0 +/- 492.6 microg min/l) was higher (P < 0.01) than that after GHRH (757.1 +/- 44.1 microg min/l). SS infusion almost abolished the GH response to GHRH (177.0 +/- 37.7 microg min/l, P < 0.01); the GH response to ghrelin was inhibited by SS (993.8 +/- 248.5 microg min/l, P < 0.01) but GH levels remained higher (P < 0.05) than with GHRH. Ghrelin induced significant increases in PRL, ACTH and cortisol levels and these responses were not modified by SS. CONCLUSIONS: Ghrelin, a natural GHS-R ligand, exerts a strong stimulatory effect on GH secretion in humans and this effect is only blunted by an exogenous somatostatin dose which almost abolishes the GH response to GHRH. The stimulatory effect of ghrelin on lactotroph and corticotroph secretion is refractory to exogenous somatostatin, indicating that these effects occur through pathways independent of somatostatinergic influence. SN - 0300-0664 UR - https://www.unboundmedicine.com/medline/citation/12030916/The_GH_releasing_effect_of_ghrelin_a_natural_GH_secretagogue_is_only_blunted_by_the_infusion_of_exogenous_somatostatin_in_humans_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&amp;sid=nlm:pubmed&amp;issn=0300-0664&amp;date=2002&amp;volume=56&amp;issue=5&amp;spage=643 DB - PRIME DP - Unbound Medicine ER -