The growth hormone response to hexarelin in patients with Prader-Willi syndrome.
Hexarelin (Hex) is a synthetic hexapeptide with potent GH-releasing activity in both animals and men. Aim of this study was to evaluate the GH response to a maximal dose of Hex and GH-releasing hormone (GHRH) in a group of patients with Prader-Willi syndrome (PWS). Seven patients (4 boys and 3 girls, age 2.4-14.2 yr) with PWS, 10 prepubertal obese children (7 boys and 3 girls, age 7.5-12.0 yr), and 24 prepubertal short normal children (11 boys and 13 girls, age 5.9-13 yr) with body weight within +/- 10% of their ideal weight were studied. All subjects were tested on two occasions with GHRH 1-29 at the dose of 1 microgram/Kg i.v., and with Hex at the dose of 2 micrograms/Kg i.v. In the PWS patients the GH response to GHRH (peak = 6.4 +/- 2.0 micrograms/l, p < 0.0001; AUC = 248 +/- 70 micrograms min/l, p < 0.0001) was significantly lower than that observed in the short normal children and similar to that observed in the obese children. In the PWS children the GH response to Hex (peak = 7.5 +/- 1.6 micrograms/l; AUC = 309 +/- 53) was similar to that observed after GHRH and significantly lower than that observed in the obese children (p < 0.05). The results of this study show that PWS patients have a blunted GH response to the administration of a maximal dose of Hex. Whether these findings reflect a more severe pituitary GH deficiency in PWS than in obese children or a deranged hypothalamic regulation of GH secretion need further investigation.
Cappa
M
M
Divisione di Pediatria e Diabetologia, Ospedale del Bambino Gesù, Palidoro, Roma, Italy.
Raguso
G
G
Palmiotto
T
T
Faedda
A
A
Gurreri
F
F
Neri
G
G
Deghenghi
R
R
Loche
S
S
D000293:Adolescent; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage; D006133:Growth Substances; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008297:Male; D009765:Obesity / Q000503:physiopathology; D009842:Oligopeptides / Q000008:administration & dosage; D011218:Prader-Willi Syndrome / Q000503:physiopathology*
D006133:Growth Substances; D009842:Oligopeptides; C086184:hexarelin; D019382:Human Growth Hormone; D013007:Growth Hormone-Releasing Hormone