The influence of insulin on circulating ghrelin

2003 ◽  
Vol 284 (2) ◽  
pp. E313-E316 ◽  
Author(s):  
Daniel E. Flanagan ◽  
Mark L. Evans ◽  
Teresa P. Monsod ◽  
Frances Rife ◽  
Rubina A. Heptulla ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Energy Homeostasis ◽  
Insulin Infusion ◽  
Significant Rise ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Physiological Regulator ◽  
Underlying Mechanisms ◽  
Mean Glucose

Ghrelin is a novel peptide that acts on the growth hormone (GH) secretagogue receptor in the pituitary and hypothalamus. It may function as a third physiological regulator of GH secretion, along with GH-releasing hormone and somatostatin. In addition to the action of ghrelin on the GH axis, it appears to have a role in the determination of energy homeostasis. Although feeding suppresses ghrelin production and fasting stimulates ghrelin release, the underlying mechanisms controlling this process remain unclear. The purpose of this study was to test the hypotheses, by use of a stepped hyperinsulinemic eu- hypo- hyperglycemic glucose clamp, that either hyperinsulinemia or hypoglycemia may influence ghrelin production. Having been stable in the period before the clamp, ghrelin levels rapidly fell in response to insulin infusion during euglycemia (baseline ghrelin 207 ± 12 vs. 169 ± 10 fmol/ml at t = 30 min, P < 0.001). Ghrelin remained suppressed during subsequent periods of hypoglycemia (mean glucose 53 ± 2 mg/dl) and hyperglycemia (mean glucose 163 ± 6 mg/dl). Despite suppression of ghrelin, GH showed a significant rise during hypoglycemia (baseline 4.1 ± 1.3 vs. 28.2 ± 3.9 μg/l at t = 120 min, P < 0.001). Our data suggest that insulin may suppress circulating ghrelin independently of glucose, although glucose may have an additional effect. We conclude that the GH response seen during hypoglycemia is not regulated by circulating ghrelin.

scholarly journals Growth Hormone-Releasing Peptide-2 Stimulates GH Secretion in GH-Deficient Patients with Mutated GH-Releasing Hormone Receptor1

2001 ◽  
Vol 86 (7) ◽  
pp. 3279-3283
Author(s):  
Rogério G. Gondo ◽  
Manuel H. Aguiar-Oliveira ◽  
César Y. Hayashida ◽  
Sergio P. A. Toledo ◽  
Neusa Abelin ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Releasing Hormone ◽  
Gh Secretion

scholarly journals From growth hormone-releasing peptides to ghrelin: discovery of new modulators of GH secretion

2006 ◽  
Vol 50 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Ana Maria J. Lengyel
Keyword(s):  
Growth Hormone ◽  
Protein Kinase ◽  
C Protein ◽  
Releasing Hormone ◽  
Gh Secretagogues ◽  
Main Site ◽  
Gh Secretion ◽  
Kinase C ◽  
Growth Hormone Releasing Peptides

Growth hormone (GH)-releasing hormone and somatostatin modulate GH secretion. A third mechanism has been discovered in the last decade, involving the action of GH secretagogues. Ghrelin is a new acylated peptide produced mainly by the stomach, but also synthesized in the hypothalamus. This compound increases both GH release and food intake. The relative roles of hypothalamic and circulating ghrelin on GH secretion are still unknown. Endogenous ghrelin might amplify the basic pattern of GH secretion, optimizing somatotroph responsiveness to GH-releasing hormone. This peptide activates multiple interdependent intracellular pathways at the somatotroph, involving protein kinase C, protein kinase A and extracellular calcium systems. However, as ghrelin induces a greater release of GH in vivo, its main site of action is the hypothalamus. In this paper we review the available data on the discovery of ghrelin, the mechanisms of action and possible physiological roles of GH secretagogues and ghrelin on GH secretion, and, finally, the regulation of GH release in man after intravenous administration of these peptides.

Pyridostigmine enhances, but does not normalise, the GH response to GH-releasing hormone in obese subjects

1990 ◽  
Vol 122 (3) ◽  
pp. 385-390 ◽  
Author(s):  
R. C. Castro ◽  
J. G. H. Vieira ◽  
A. R. Chacra ◽  
G. M. Besser ◽  
A. B. Grossman ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Acetylcholinesterase Inhibitor ◽  
Random Order ◽  
Normal Subjects ◽  
Obese Patients ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Obese Subjects ◽  
Higher Doses ◽  
Hormone Responsiveness

Abstract Obese patients are characterised by several neuroendocrine abnormalities, including characteristically a decrease in growth hormone responsiveness to GH-releasing hormone. In normal subjects, the GH response to GHRH is enhanced by the acetylcholinesterase inhibitor, pyridostigmine. We have studied the effect of this drug on GH secretion in gross obesity. Twelve obese patients were studied (mean weight 156% of ideal) and compared with a group of 8 normal volunteers. Each subject was initially studied on two occasions, in random order, with GHRH (1–29) NH2 100 μg iv alone and following pretreatment with pyridostigmine 120 mg orally one hour prior to GHRH. In obese patients, the GH response to GHRH was significantly blunted when compared to controls (GH peak: 20 ± 4 vs 44 ± 16 μg/l; mean ± sem). After pyridostigmine, the response to GHRH was enhanced in the obese subjects, but remained significantly reduced compared to non-obese subjects treated with GHRH and pyridostigmine (GH peak: 30 ± 5 vs 77 ± 20 μg/l, respectively). In 6 subjects, higher doses of GHRH or pyridostigmine did not further increase GH responsiveness in obese patients. Our results suggest that obese patients have a disturbed cholinergic control of GH release, probably resulting from increased somatostatinergic tone. This disturbed regulation may be responsible, at least in part, for the blunted GH responses to provocative stimuli.

Corticotrophin-releasing hormone does not inhibit growth hormone-releasing hormone-induced release of growth hormone in control subjects but is effective in patients with eating disorders

1994 ◽  
Vol 140 (2) ◽  
pp. 327-332 ◽  
Author(s):  
M Rolla ◽  
A Andreoni ◽  
D Bellitti ◽  
M Ferdeghini ◽  
E Ghigo ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Eating Disorders ◽  
Young Women ◽  
Animal Studies ◽  
Area Under The Curve ◽  
Inhibitory Influence ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Not Otherwise Specified ◽  
Normal Women

Abstract Previous studies have shown that corticotrophin-releasing hormone (CRH) inhibits GH secretion in response to GH-releasing hormone (GHRH) in normal women and men, and animal studies suggest that this effect is mediated by an increased release of somatostatin from the hypothalamus. It has been reported that there are abnormalities in the neuroendocrine regulation of the hypothalamo-pituitary-somatotrophic axis and the hypothalamo-pituitary-adrenocortical axis in patients with eating disorders. The present study therefore investigated the ability of CRH to inhibit the GH response to GHRH in eight young women with anorexia nervosa (AN) and in seven young women with eating disorders which were not otherwise specified (NOS). We also compared the effect of CRH in the patients with the response it caused in ten control women. In contrast to a previous report, combined i.v. administration of 50 μg human CRH (hCRH) and 50 μg GHRH(1–29) caused a GH response in control women which was higher, although not significantly so, than that induced by GHRH alone (area under the curve (AUC) 988·5 ±506·0 compared with 1568·4 ±795·6 (s.e.m.) ng/ml per 120 min for GHRH alone and GHRH plus hCRH respectively). Conversely, the administration of hCRH given together with GHRH markedly inhibited the GH response induced by the latter in both AN patients (AUC 2253·0 ±385·7 compared with 1224·4 ±265·7 ng/ml per 120 min for GHRH and GHRH plus hCRH respectively; P<0·005 and NOS patients (AUC 2827·4±281·1 compared with 308·5 ± 183·4 ng/ml per 120 min for GHRH and GHRH plus hCRH respectively; P<0·0001). These results (1) refute the suggestion that there is an inhibitory influence of CRH over GH secretion under normal conditions, (2) indicate that this inhibitory influence exists in patients with eating disorders, and (3) imply that, in the latter, hypothalamic somatostatinergic function is, at least in part, preserved. Journal of Endocrinology (1994) 140, 327–332

scholarly journals Specific Involvement of Gonadal Hormones in the Functional Maturation of Growth Hormone Releasing Hormone (GHRH) Neurons

Endocrinology ◽  
2010 ◽  
Vol 151 (12) ◽  
pp. 5762-5774 ◽  
Author(s):  
Laurie-Anne Gouty-Colomer ◽  
Pierre-François Méry ◽  
Emilie Storme ◽  
Elodie Gavois ◽  
Iain C. Robinson ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Postnatal Development ◽  
Potassium Current ◽  
Hormonal Treatment ◽  
Gonadal Hormones ◽  
Detailed Knowledge ◽  
Releasing Hormone ◽  
Electrophysiological Properties ◽  
Gh Secretion ◽  
Voltage Dependent

Growth hormone (GH) is the key hormone involved in the regulation of growth and metabolism, two functions that are highly modulated during infancy. GH secretion, controlled mainly by GH releasing hormone (GHRH), has a characteristic pattern during postnatal development that results in peaks of blood concentration at birth and puberty. A detailed knowledge of the electrophysiology of the GHRH neurons is necessary to understand the mechanisms regulating postnatal GH secretion. Here, we describe the unique postnatal development of the electrophysiological properties of GHRH neurons and their regulation by gonadal hormones. Using GHRH-eGFP mice, we demonstrate that already at birth, GHRH neurons receive numerous synaptic inputs and fire large and fast action potentials (APs), consistent with effective GH secretion. Concomitant with the GH secretion peak occurring at puberty, these neurons display modifications of synaptic input properties, decrease in AP duration, and increase in a transient voltage-dependant potassium current. Furthermore, the modulation of both the AP duration and voltage-dependent potassium current are specifically controlled by gonadal hormones because gonadectomy prevented the maturation of these active properties and hormonal treatment restored it. Thus, GHRH neurons undergo specific developmental modulations of their electrical properties over the first six postnatal weeks, in accordance with hormonal demand. Our results highlight the importance of the interaction between the somatotrope and gonadotrope axes during the establishment of adapted neuroendocrine functions.

Reproducibility of the growth hormone response to stimulation with growth hormone-releasing hormone plus arginine during lifespan

1996 ◽  
Vol 135 (5) ◽  
pp. 568-572 ◽  
Author(s):  
Maria Rosa Valetto ◽  
Jaele Bellone ◽  
Claudia Baffoni ◽  
Paola Savio ◽  
Gianluca Aimaretti ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Gh Deficiency ◽  
Normal Subjects ◽  
Individual Variability ◽  
Hormone Response ◽  
Female Age ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Subject Variability ◽  
Within Subject Variability

Valetto MR, Bellone J, Baffoni C, Savio P, Aimaretti G, Gianotti L, Arvat E, Camanni F, Ghigo E. Reproducibility of the growth hormone response to stimulation with growth hormone-releasing hormone plus arginine during lifespan. Eur J Endocrinol 1996;135:568–72. ISSN 0804–4643 The reliability and reproducibility of provocative stimuli of growth hormone (GH) secretion in the diagnosis of GH deficiency are still controversial both in childhood and in adulthood. The combined administration of GH-releasing hormone (GHRH) and arginine (ARG), which likely acts via inhibition of hypothalamic somatostatin release, is one of the most potent stimuli known so far and has been proposed recently as the best test to explore the maximal somatotrope capacity of somatotrope cells. However, it is well known that, usually, provocative stimuli of GH secretion suffer from poor reproducibility and that of the GHRH + ARG test has still to be verified. We aimed to verify the between- and within-subject variability of the GH response to the GHRH + ARG test in normal subjects during their lifespan as well as in hypopituitaric patients with GH deficiency (GHD). In 10 normal children (C: six male and four female, age 12.3 ± 0.9 years, body mass index (BMI) = 16.6 ± 0.7 kg/m2, pubertal stages I-III), 18 normal young adults (Y: ten male and eight female, age 31.1 ± 1.3 years, BMI = 21.4 ± 0.4 kg/m2), 12 normal elderly subjects (E: two male and ten female, age 74.4 ± 1.8 years, BMI= 22.6 ± 0.6 kg/m2) and 15 panhypopituitaric GH-deficient patients (GHD: nine male and six female, age 40.9 ± 4.1 years, BMI= 22.7 ± 1.0 kg/m2), we studied the inter- and intra-individual variability of the GH response to GHRH (1 μg/kg iv) + ARG (0.5 g/kg iv) in two different sessions at least 3 days apart. The GH responses to GHRH + ARG in C (1st vs 2nd session: 61.6 ± 8.1 vs 66.5 ± 9.4 μg/l), Y (70.4 ± 10.1 vs 76.2 ± 10.7 μg/l) and E (57.9 ± 14.8 vs 52.1 ± 8.0 μg/l) were similar and reproducible in all groups. The somatotrope responsiveness to GHRH + ARG also showed a limited within-subject variability (r = 0.71, 0.90 and 0.89 and p < 0.02, 0.0005 and 0.0005 for C, Y and E, respectively). Similarly in GHD, the GH response to the GHRH + ARG test showed a good inter- (1st vs 2nd session: 2.3 ± 0.5 vs 2.2 ± 0.6 μg/l) and intra-individual reproducibility (r = 0.70, p < 0.005). The GHRH + ARG-induced GH responses in GHD were markedly lower (p < 0.0005) than those in age-matched controls and no overlap was found between GH peak responses in GHD and normal subjects. In normal subjects, the GH response to GHRH + ARG is very marked, independent of age and shows limited inter- and intra-individual variability. The GH response to the GHRH + ARG test is strikingly reduced in panhypopituitaric patients with GHD, in whom the low somatotrope responsiveness is reproducible. Thus, these findings strengthen the hypothesis that GHRH + ARG should be considered the most reliable test to evaluate the maximal secretory capacity of somatotrope cells and to distinguish normal subjects from GHD patients in adulthood. E. Ghigo, Divisione di Endocrinologia, Ospedale Molinette, C.so Dogliotti 14, 10126, Torino, Italy

Growth hormone-releasing hormone in the diagnosis and treatment of growth hormone deficient children

1986 ◽  
Vol 113 (4_Suppl) ◽  
pp. S123-S129
Author(s):  
R.J.M. ROSS ◽  
A. GROSSMAN ◽  
G.M. BESSER ◽  
M.O. SAVAGE
Keyword(s):  
Growth Hormone ◽  
Linear Growth ◽  
Gh Deficiency ◽  
Venous Blood ◽  
Alternative Therapy ◽  
Normal Subjects ◽  
Growth Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Depot Preparations

ABSTRACT A growth hormone-releasing hormone (GHRH) has recently been extracted and synthesised, and appears to be identical to human hypothalamic GHRH. Immunoreactive GHRH is found in the venous blood of normal subjects and GH-deficient children, but is probably not hypothalamic in origin and therefore not important in GH regulation. GHRH is a potent specific stimulator of GH secretion in man, and provides a valuable diagnostic test in differentiating hypothalamic from pituitary causes of GH deficiency. Preliminary data suggests that GHRH may promote linear growth in some GH deficient children. GHRH may well prove an important alternative therapy for GH deficient children especially if depot preparations or intranasal administration prove effective.

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