GROWTH HORMONE-RELEASING ACTIVITY OF GROWTH HORMONE-RELEASING PEPTIDE-1 (A SYNTHETIC HEPTAPEPTIDE) IN CHILDREN AND ADOLESCENTS

The heptapeptide growth hormone-releasing peptide-1 (GHRP-1), one of a series of recently synthesized small growth hormone (GH)-releasing pe ptides, was administered as an iv bolus (1 mug/kg) to 15 (six prepuber tal, nine pubertal) short but healthy children and adolescents and to eight juvenile patients with pituitary insufficiency (four with isolat ed growth hormone deficiency, two with multiple pituitary hormone defi ciencies, one with partial GH deficiency and one with GH-releasing hor mone (GHRH) deficiency). Eleven out of 2 3 subjects also underwent an iv GHRH (1-29) test (1 mug/kg). All the healthy children responded wit h a progressive rise in plasma human GH (hGH) peaking at 15-30 min, wi th a significantly higher rise (p < 0.05) in the pubertal than prepube rtal group. The hGH response to GHRH (1-29) in these children was simi lar or slightly higher. Six hypopituitary patients had no response to either GHRP-1 or GHRH; the patient with partial GH deficiency had a hG H peak of 6.5 mug/l (at 5 min) to GHRP-1 and 9.2 mug/l (at 15 min) to GHrH. One patient had no response of hGH to hypoglycemia, clonidine an d GHRP-1, but the plasma hGH rose to 10 mug/l after GHRH. Following th e GHRP-1 bolus there was a significant (p < 0.01) rise in plasma free thyroxine and a decrease of thyrotropin (p < 0.01), both in the limits of normal values. There was also a transitory rise of plasma cortisol (p < 0.05). Plasma prolactin, luteinizing hormone and follicle-stimul ating hormone did not change. It is concluded that GHRP-1 is a potent GH-releasing drug because it acts also when administered orally and ha s great pharmaceutical and clinical applications.