Ghrelin Main Action on the Regulation of Growth Hormone Release Is Exerted at Hypothalamic Level

• Published in: The journal of clinical endocrinology and metabolism 2003-07, Vol.88 (7), p.3450-3453
• Main Authors: Popovic, V., Miljic, D., Micic, D., Damjanovic, S., Arvat, E., Ghigo, E., Dieguez, C., Casanueva, F. F.
• Format: Article
• Language: English
• Subjects: Adult; Astrocytoma - drug therapy; Astrocytoma - metabolism; Biological and medical sciences; Craniopharyngioma - drug therapy; Craniopharyngioma - metabolism; Empty Sella Syndrome - drug therapy; Empty Sella Syndrome - metabolism; Female; Fundamental and applied biological sciences. Psychology; Ghrelin; Hormones and neuropeptides. Regulation; Human Growth Hormone - deficiency; Human Growth Hormone - metabolism; Human Growth Hormone - secretion; Humans; Hypothalamus - drug effects; Hypothalamus - metabolism; Hypothalamus - secretion; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Male; Meningeal Neoplasms - drug therapy; Meningeal Neoplasms - metabolism; Meningioma - drug therapy; Meningioma - metabolism; Middle Aged; Peptide Hormones - administration & dosage; Peptide Hormones - metabolism; Pituitary Neoplasms - drug therapy; Pituitary Neoplasms - metabolism; Vertebrates: endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2003-030211

Ghrelin, a recently isolated hormone, seems to participate in the physiological regulation of GH secretion. Exogenously administered ghrelin stimulates GH discharge in all species so far tested including man, but whether this action is exerted at pituitary or alternatively at hypothalamic level is not known at present. To understand the point of ghrelin action a group of patients with organic lesion mainly in the hypothalamic areq and matched controls were studied. Patients showed a severe GH deficiency after hypothalamic stimulation (ITT), but partial response after GHRH administration. Cases and controls were tested on three separate days by either ghrelin; GHRH; and ghrelin plus GHRH; always at 1 μg/Kg iv. The mean GH peak after stimulation in the patients were: 0.4 ± 0.1 μg/L by ITT; 3.1 ± 0.5 μg/L after GHRH; 2.0 ± 0.8 μg/L after ghrelin; and 9.6 ± 2.9 μg/L after the combination of GHRH plus ghrelin. In the controls GHRH induced a GH peak of 21.2 ± 7.5 μg/L, and 75.1 ± 16.0 μg/L after ghrelin with a peak after GHRH + ghrelin of 103.5 ± 26.4 μg/L. These data indicate that when hypothalamic structures are not operative ghrelin, either alone or in combination with GHRH, is not able to significantly release GH. In addition to postulating a hypothalamic point of action for the ghrelin-induced GH secretion, these results suggests that ghrelin will not have significant clinical utility in patients with GH deficiency due to organic lesion.