Effects of glucose, free fatty acids or arginine load on the GH‐releasing activity of ghrelin in humans

Broglio, Fabio; Benso, Andrea; Gottero, Cristina; Prodam, Flavia; Grottoli, Silvia; Tassone, F.; Maccario, Mauro; Casanueva, Felipe F.; Diéguez, Carlos; Deghenghi, Romano; Ghigo, Ezio; Arvat, Emanuela

doi:10.1046/j.1365-2265.2002.01595.x

Cited by 60 publications

(36 citation statements)

References 56 publications

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“…Hyperglycemia, free fatty acids and somatostatin decrease GHRP-6 and the ghrelin-induced GH response (45,46). Arginine was not able to alter GH responsiveness to ghrelin (47).…”

Section: Regulation Of Gh Secretion By Ghrp-6 and Ghrelin In Manmentioning

confidence: 98%

Novel mechanisms of growth hormone regulation: growth hormone-releasing peptides and ghrelin

Lengyel

2006

Braz J Med Biol Res

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Growth hormone secretion is classically modulated by two hypothalamic hormones, growth hormone-releasing hormone and somatostatin. A third pathway was proposed in the last decade, which involves the growth hormone secretagogues. Ghrelin is a novel acylated peptide which is produced mainly by the stomach. It is also synthesized in the hypothalamus and is present in several other tissues. This endogenous growth hormone secretagogue was discovered by reverse pharmacology when a group of synthetic growth hormone-releasing compounds was initially produced, leading to the isolation of an orphan receptor and, finally, to its endogenous ligand. Ghrelin binds to an active receptor to increase growth hormone release and food intake. It is still not known how hypothalamic and circulating ghrelin is involved in the control of growth hormone release. Endogenous ghrelin might act to amplify the basic pattern of growth hormone secretion, optimizing somatotroph responsiveness to growth hormone-releasing hormone. It may activate multiple interdependent intracellular pathways at the somatotroph, involving protein kinase C, protein kinase A and extracellular calcium systems. However, since ghrelin has a greater ability to release growth hormone in vivo, its main site of action is the hypothalamus. In the current review we summarize the available data on the: a) discovery of this peptide, b) mechanisms of action of growth hormone secretagogues and ghrelin and possible physiological role on growth hormone modulation, and c) regulation of growth hormone release in man after intravenous administration of these peptides. Correspondence

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“…Hyperglycemia, free fatty acids and somatostatin decrease GHRP-6 and the ghrelin-induced GH response (45,46). Arginine was not able to alter GH responsiveness to ghrelin (47).…”

Section: Regulation Of Gh Secretion By Ghrp-6 and Ghrelin In Manmentioning

confidence: 98%

Novel mechanisms of growth hormone regulation: growth hormone-releasing peptides and ghrelin

Lengyel

2006

Braz J Med Biol Res

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“…Research activities have focused on the stimulatory effect of ghrelin on food intake and its role in the modulation of energy expenditure (10 ). Ghrelin plays a major role in the gastrointestinal tract, stimulating gastric contractility and acid secretion (11 ), and it is responsible for the metabolic response to starvation by modulating insulin secretion (12 ), glucose metabolism (13 ), and amino acid uptake (14 ). Furthermore, it affects cardiovascular activity (15 ) by acting as a vasodilator.…”

mentioning

confidence: 99%

Identification of Ghrelin in Human Saliva: Production by the Salivary Glands and Potential Role in Proliferation of Oral Keratinocytes

Gröschl¹,

Topf²,

et al. 2005

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Background:We investigated whether ghrelin is present in human saliva, is produced by salivary glands, and physiologic consequences of these findings. Methods: Expression of ghrelin and specific receptor mRNA was determined by PCR. Proteins were identified by immunoblotting and size-exclusion fast protein liquid chromatography (FPLC) with consecutive RIA. Specific RIAs were used for quantification of salivary total and bioactive ghrelin. Distribution of ghrelin was investigated by immunohistochemistry in cryosections of the salivary glands. The effect of ghrelin on incorporation of 5-bromo-2-deoxyuridine as a measure of cell proliferation was investigated in primary oral keratinocytes. Results: Ghrelin is produced by the salivary glands. The hormone was identified in saliva and glands by immunoblotting and by FPLC fractionation of saliva. Immunohistochemistry demonstrated ghrelin distribution in the salivary glands. The receptor was also produced by the glands and by oral keratinocytes and was shown to be functional. Comparison of total ghrelin values for healthy individuals (body mass index, 18 -27 kg/m 2 ) showed significantly lower concentrations in saliva than in serum (P <0.01). The correlation between both matrices was r 2 ‫؍‬ 0.56 (P <0.001) with a negative correlation to body mass index (r 2 ‫؍‬ 0.314; P <0.01). Bioactive acylated ghrelin was also present in saliva. Incubation of keratinocytes with ghrelin led to signifi-

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“…It is possible however, that the fasting state of the subjects lasting more than 12 h before starting the experiment, had already led to high ghrelin t 0 values, which then facilitated the hGH release after the AA uptake. Another possible explanation for this finding is that the strong stimulatory effect of ghrelin on the release of hGH may partially be equalised by the inhibitory influence of the slight, insignificant increase of FFA levels on hGH (Broglio et al 2002). Furthermore, recently published data indicate that ghrelin release is not suppressed by insulin (Caixas et al 2002); moreover insulin secretion seems to be additionally stimulated by ghrelin, as has been shown in rodents (Adeghate & Ponery 2002).…”

Section: Discussionmentioning

confidence: 74%

Endocrine responses to the oral ingestion of a physiological dose of essential amino acids in humans

Gröschl¹,

Knerr²,

Hg³

et al. 2003

Journal of Endocrinology

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The response of insulin, human growth hormone (hGH), cortisol, leptin and ghrelin, in addition to various metabolic parameters, was measured at 10 minute intervals following the oral ingestion of a standardised physiological dose of essential amino acids (AA). Twenty-eight healthy male, fasted volunteers (aged 18-40 yrs, BMI 18·0-24·5 kg/m 2 ) took part in the study; 13 volunteers in the AA group, nine subjects in an iso-caloric control group, and a further six subjects served as fasting controls.Twenty minutes after ingestion, insulin reached peak concentrations that were up to 500% higher than basal values (P,0·0001). The AA group and iso-caloric control group showed a similar insulin response.AA ingestion led to an increase in hGH secretion with maximum concentrations being 2100 1013% higher than the basal values (P,0·0001). In contrast, no changes in hGH concentrations were observed in the iso-caloric controls; in the fasting controls only a slight increase in hGH was found towards the end of the fasting period.While cortisol decreased significantly (P,0·01) during the study in the AA group, neither control group showed a significant change in this parameter.Changes in leptin levels remained insignificant in all three groups, whereas ghrelin showed a different profile in each of the three groups, i.e. a continuous rise towards the end of the study period (P,0·001) in the AA group, a less significant effect for the fasting group, and no effect at all in the iso-caloric control group.There was no significant correlation between the concentrations or the area under curve of the hormones measured in any of the groups.The endocrine data provided in this study indicate that a single bolus of essential AA in fasted individuals is associated with both anabolic and catabolic hormonal responses.

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Effects of glucose, free fatty acids or arginine load on the GH‐releasing activity of ghrelin in humans

Cited by 60 publications

References 56 publications

Novel mechanisms of growth hormone regulation: growth hormone-releasing peptides and ghrelin

Novel mechanisms of growth hormone regulation: growth hormone-releasing peptides and ghrelin

Identification of Ghrelin in Human Saliva: Production by the Salivary Glands and Potential Role in Proliferation of Oral Keratinocytes

Endocrine responses to the oral ingestion of a physiological dose of essential amino acids in humans

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