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Hexarelin

Examorelin, HEX

A synthetic hexapeptide growth hormone secretagogue that stimulates GH release by acting on the ghrelin receptor in the pituitary and hypothalamus.

Quick Stats
Studies 233
Trials 61
Formula C47H58N12O6
Overview Studies 233 Clinical Trials 61
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pubmed 2000

Interaction between glucagon and hexarelin, a peptidyl GH secretagogue, on somatotroph and corticotroph secretion in humans.

Arvat. E E; Maccagno. B B; Ramunni. J J; Giordano. R R; Broglio. F F; Gianotti. L L; Maccario. M M;...

Glucagon administration stimulates both somatotroph and corticotroph secretion in humans, although this happens only if glucagon is administered by the intramuscular route and not by the intravenous route. On the other hand, GH secretagogues (GHS) strongly stimulate GH and also possess ACTH-releasing activity. To clarify the mechanisms underlying the stimulatory effects of both glucagon and GHS on somatotroph and corticotroph secretion, we studied the GH, ACTH and cortisol responses to glucagon (GLU, 0.017 mg/kg i.m.) and Hexarelin, a peptidyl GHS (HEX, 2.0 microg/kg i.v.) given alone or in combination in 6 normal young volunteers (females, aged 26-32 years, body mass index 19.7-22.5 kg/m). GLU administration elicited a clear increase in GH (peak vs baseline, mean+/-S.E.M.: 11.6+/-3.4 vs 3. 3+/-0.7 microg/l, P<0.02), ACTH (11.6+/-3.3 vs 4.1+/-0.3 pmol/l, P<0. 02) and cortisol (613.5+/-65.6 vs 436.9+/-19.3 nmol/l, P<0.05) levels. HEX induced a marked increase in GH levels (55.7+/-19.8 vs 3. 7+/-1.9 microg/l, P<0.005) and also significant ACTH (5.7+/-1.1 vs 3. 4+/-0.6 pmol/l, P<0.01) and cortisol (400.2+/-31.4 vs 363.4+/-32.2 nmol/l, P<0.05) responses. The GH area under the curve (AUC) after HEX was clearly higher than after GLU (1637.3+/-494.0 vs 479.1+/-115. 7 microg/l/120 min, P<0.04) while HEX and GLU coadministration had a true synergistic effect on GH release (3243.8+/-687.5 microg/l/120 min, P<0.02). The ACTH and cortisol AUCs after HEX were lower (P<0. 02) than those after GLU (208.3+/-41.3 vs 426.3+/-80.9 pmol/l/120 min and 18 874.5+/-1626.1 vs 28 338.5+/-2430.7 nmol/l/120 min respectively). The combined administration of HEX and GLU had an effect which was less than additive on both ACTH (564.02+/-76.5 pmol/l/120 min) and cortisol (35 424.6+/-5548.1 nmol/l/120 min) secretion. These results show that the intramuscular administration of glucagon releases less GH but more ACTH and cortisol than Hexarelin. The combined administration of glucagon and Hexarelin has a true synergistic effect on somatotroph secretion but a less than additive effect on corticotroph secretion; these findings suggest that these stimuli act via different mechanisms to stimulate somatotrophs while they could have a common action on the hypothalamo-pituitary-adrenal axis.

pubmed 1999

Effects of alprazolam, a benzodiazepine, on the ACTH-, GH- and PRL-releasing activity of hexarelin, a synthetic peptidyl GH secretagogue (GHS), in patients with simple obesity and in patients with Cushing's disease.

Grottoli. S S; Arvat. E E; Gauna. C C; Maccagno. B B; Ramunni. J J; Giordano. R R; Maccario. M M; De...

GH secretagogues (GHS) possess potent GH-releasing activity but also stimulate PRL, ACTH and cortisol (F) secretion. To further clarify the endocrine activities of GHS, in 9 obese patients, 9 patients with Cushing's disease and 14 controls we studied the ACTH, F, GH and PRL responses to hexarelin (HEX, 2.0 micrograms/kg i.v.), a peptidyl GHS, alone and preceeded by alprazolam (ALP, 0.02 mg/kg p.o.), a benzodiazepine. The HEX-induced ACTH response in controls was similar to that in obese patients (delta peak: 9.9 +/- 1.9 and 24.7 +/- 7.6 ng/L, respectively) and both were lower (p < 0.002) than that in Cushing's patients (peak: 210.7 +/- 58.4 ng/L). The GH response to HEX in controls (peak: 58.1 +/- 10.3 x g/L) was higher (p < 0.001) than those in obese and Cushing's patients (18.2 +/- 3.8 and 12.6 +/- 5.4 x g/L, respectively) which, in turn, were similar. The PRL responses to HEX in controls, obese and Cushing's patients (peak: 11.9 +/- 1.6, 18.0 +/- 4.5 and 12.4 +/- 1.4 x g/L, respectively) were similar. In controls the HEX-induced ACTH response was abolished by ALP (peak: 8.6 +/- 2.4 vs 28.0 +/- 6.7 ng/L, p < 0.03) which, on the other hand, only blunted that in obese (peak: 12.7 +/- 2.1 vs 42.4 +/- 8.4 ng/L, p < 0.02) and did not modify that in Cushing's patients (205.6 +/- 55.4 vs 175.9 +/- 47.6 ng/L). ALP blunted the GH response to HEX in controls (peak: 31.0 +/- 7.1 x g/L, p < 0.03) while did not modify those in obese and in Cushing's patients (14.5 +/- 5.3 and 13.3 +/- 11.1 x g/L, respectively). ALP did not modify the HEX-induced PRL response in controls, obese and Cushing's patients (peak: 13.8 +/- 0.9, 16.3 +/- 2.4 and 19.2 +/- 1.1 x g/L, respectively). In conclusion, alprazolam inhibits the ACTH response to hexarelin in normal and obese subjects while fails to modify the exaggerated ACTH response in Cushing's Disease suggesting that GHS activate the HPA axis via the hypothalamus in normal and obese subjects but not in patients with Cushing's disease. Alprazolam is also able to blunt the GH-releasing activity of hexarelin in normal subjects but not the low GH response to the hexapeptide in obese and Cushing's patients. The PRL-releasing activity of hexarelin in controls, obese and hypercortisolemic patients is similar and is not modified by alprazolam pretreatment.