Hexarelin, a synthetic growth hormone releasing peptide, stimulates prolactin secretion in acromegalic but not in hyperprolactinaemic patients

Ciccarelli, Enrica; Grottoli, Silvia; Razzore, Paola; Gianotti, Laura; Arvat, Emanuela; Deghenghi, Romano; Camanni, Guido; Ghigo, Ezio

doi:10.1046/j.1365-2265.1996.626446.x

Cited by 41 publications

(16 citation statements)

References 20 publications

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“…GHRPs release PRL from human pituitary (24) and the GHRP-induced PRL rise is preserved in acromegalic patients bearing a somatomammotrope adenoma but not in patients bearing a pure prolactinoma (25). The evidence that HEX-induced PRL release does not vary with age suggests that the PRL-releasing effect of GHRPs is not influenced by estrogen levels and dopaminergic tone, which play a well-known role in the age-related variations of both spontaneous and stimulated PRL secretion (28).…”

Section: Discussionmentioning

confidence: 80%

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The GH, prolactin, ACTH and cortisol responses to Hexarelin, a synthetic hexapeptide, undergo different age-related variations

Arvat

Ramunni

Bellone

et al. 1997

European Journal of Endocrinology

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Hexarelin (HEX) is a synthetic growth hormone-releasing peptide (GHRP) which acts on specific receptors at both the pituitary and the hypothalamic level to stimulate GH release in an age-dependent manner. Like other GHRPs, HEX possesses also prolactin (PRL) and ACTH/cortisol-releasing activity, similar to that of human corticotropin-releasing hormone (hCRH). The mechanisms underlying the stimulatory effect of GHRPs on lactotrope and corticotrope secretion are even less clear and the influence of age on these endocrine activities of GHRPs is unknown. To clarify this point we studied the GH, PRL, ACTH and cortisol responses to the maximal effective dose of HEX (2.0 mg/kg i.v.) in: 12 prepubertal children (Pre-C, 8 male, 4 female, age 5.8-12

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Section: Discussionmentioning

confidence: 80%

“…Concerning the PRL-releasing activity of GHRPs, very little is known about the mechanism underlying this effect, though a direct effect at the pituitary level has been hypothesized (24,25).…”

Section: Introductionmentioning

confidence: 99%

The GH, prolactin, ACTH and cortisol responses to Hexarelin, a synthetic hexapeptide, undergo different age-related variations

Arvat

Ramunni

Bellone

et al. 1997

European Journal of Endocrinology

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“…However, GHS administration to patients with prolactinomas does not stimulate further PRL release, and the GH response is blunted [78]. We also showed that ghrelin stimulates proliferation of GH3 cells, a somatomammotroph tumour cell line, via activation of the MAPK pathway.…”

Section: Ghrelin In Prolactinomasmentioning

confidence: 79%

Ghrelin in neuroendocrine organs and tumours

2007

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Ghrelin is a 28 amino-acid hormone with multiple functions. It is predominantly produced by the stomach but has also been detected in other organs, including the small intestine, pancreas, hypothalamus and pituitary, as well as in the immune system and almost every other normal human tissue examined. It is also present in neuroendocrine tumours, pituitary adenomas, endocrine tumours of the pancreas, breast tumours, and thyroid and medullary thyroid carcinomas. Ghrelin is a brain-gut peptide with growth hormone-releasing and appetite-inducing activities, and is the endogenous ligand of the G protein-coupled growth hormone secretagogue receptor (GHS-R). In this review we comprehensively summarize the available data regarding (a) the expression of ghrelin and the GHS-R in normal endocrine tissues and in pituitary adenomas and neuroendocrine tumours, (b) the levels of circulating ghrelin in patients with pituitary adenomas and neuroendocrine tumours and (c) the effects of ghrelin administration in these patients on the levels of other hormones and on the rate of proliferation of the tumour. It is clear that ghrelin has many more functions and is involved in many more processes than was initially postulated, and its endocrine, paracrine and autocrine effects play a role in its physiological and pathophysiological functions.

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“…This is the first report on the effects of ghrelin in patients with acromegaly and it shows that chronic GH hypersecretion does not markedly influence the hormone responses per se. GHS receptor expression is very high in GH-producing adenomas (16) and hexarelin, a synthetic GHS, possesses GH-and PRL-releasing activity in acromegalic patients (17,18). The positive correlation between the extent of the ghrelin-elicited GH increase and the basal IGF-I concentrations in acromegalic patients suggests that GHSs are useful tools in assessing GH secretory capacity in both normal and pathological conditions, in agreement with previous findings in healthy subjects after hexarelin administration (19).…”

Section: Discussionmentioning

confidence: 99%

Ghrelin administration affects circulating pituitary and gastro-entero-pancreatic hormones in acromegaly

Arosio¹,

Ronchi²,

Gebbia³

et al. 2004

European Journal of Endocrinology

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Objective: Ghrelin, a gut -brain peptide involved in the control of energy homeostasis, affects anteropituitary and gastro-entero-pancreatic (GEP) hormone secretion in healthy subjects. We aimed to verify whether such hormonal responses are retained in acromegaly, a disease characterized by high GH, subnormal ghrelin and abnormal GEP hormone levels. Design and methods: The effect of ghrelin (3.3 mg/kg given after overnight fasting as an i.v. bolus) on GH, prolactin (PRL), adrenocorticotropin (ACTH), cortisol, insulin, glucose, total somatostatin (SS) and pancreatic polypeptide (PP) circulating levels were evaluated in seven non-diabetic patients with newly diagnosed acromegaly and in nine healthy controls. Results: Ghrelin elicited a prompt, marked increase of serum GH and PRL levels in all normal (from 1.6^0.6 to 52.9^7.8 and from 9.7^0.8 to 24.2^4.8 mg/l (means^S.E.M.), respectively) and acromegalic subjects (from 11.2^4.9 to 91.6^21.0 and from 42.9^26.1 to 113.8^79.0 mg/l, respectively). Both plasma ACTH and serum cortisol levels rose significantly in the controls, whereas the cortisol response was blunted in the acromegalic patients. Glucose levels rose earlier and insulin levels fell later in all subjects, with a significantly greater net insulin decrease in acromegalic than in healthy subjects (2 80^21 vs 2 17^4 pmol/l, P , 0.01). A prompt PP rise and a biphasic SS response occurred in all controls, whereas in the acromegalic group the PP response (from 26.1^5.0 to 92.2^39.0 pmol/l) and the SS response (from 11.9^3.0 to 19.7^4.0 ng/l) were quite variable. Conclusions: Ghrelin affects both pituitary and GEP hormones in acromegalic patients as in normal subjects. These findings suggest that ghrelin actions on the energy balance are mediated by complex interactive endocrine loops that involve also the gut and pancreas.

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Hexarelin, a synthetic growth hormone releasing peptide, stimulates prolactin secretion in acromegalic but not in hyperprolactinaemic patients

Cited by 41 publications

References 20 publications

The GH, prolactin, ACTH and cortisol responses to Hexarelin, a synthetic hexapeptide, undergo different age-related variations

The GH, prolactin, ACTH and cortisol responses to Hexarelin, a synthetic hexapeptide, undergo different age-related variations

Ghrelin in neuroendocrine organs and tumours

Ghrelin administration affects circulating pituitary and gastro-entero-pancreatic hormones in acromegaly

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