Journal of Clinical Endocrinology & Metabolism, Vol 80, 1090-1094, Copyright © 1995 by Endocrine Society

ARTICLES

Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, before and during puberty

J Bellone, G Aimaretti, E Bartolotta, L Benso, BP Imbimbo, V Lenhaerts, R Deghenghi, F Camanni and E Ghigo
Department of Clinical Pathophysiology, University of Turin, Italy.

The objective of this study was to verify the GH-releasing activity of a synthetic hexapeptide, hexarelin (HEX), before and during puberty. Ninety-six children (54 boys and 42 girls, aged 4.1-17.4 yr) were studied. Fifty-two of the children were prepubertal, and the other 44 were in pubertal stage II-IV. The GH response to 2 micrograms/kg HEX, iv (n = 56), was higher (P < 0.001) than that induced by 1 microgram/kg GHRH, iv (n = 33). The iv dose of 2.0 micrograms/kg HEX induced a greater GH increase (P < 0.02) than the 1.0 microgram/kg dose. The GH- releasing effect of 10 mg HEX, orally, was greater (P < 0.03) than that of 1.0 microgram/kg GHRH, iv (n = 7). The iv dose of 2 micrograms/kg HEX elicited an increase in GH levels that was higher in pubertal children than in prepubertal children (77.5 +/- 8.5 vs. 39.4 +/- 4.4 micrograms/L; P < 0.001). Before puberty, there was no sex-dependent difference in the GH response to HEX. It increased during puberty (P < 0.05 and P < 0.002 for boys and girls, respectively), when it was higher (P < 0.05) in girls than in boys. In contrast, GH responses to GHRH were not related to sex differences and/or puberty. In conclusion, HEX is a potent and reproducible stimulus of GH secretion in children. The effect of HEX increases in puberty, with girls showing a more marked GH response.

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