Arginine potentiates the GHRH- but not the pyridostigmine-induced GH secretion in normal short children. Further evidence for a somatostatin suppressing effect of arginine.
To investigate the mechanism underlying the GH-releasing effect of arginine (ARG), we studied the interactions of ARG (0.5 g/kg infused i.v. over 30 min) with GHRH (1 microgram/kg i.v.) and with pyridostigmine (PD, 60 mg orally) on GH secretion in 15 children and adolescents with familial short stature (5.1-15.4 years). In a group of eight subjects ARG induced a GH increase not statistically different to that observed after GHRH (peak, mean +/- SEM: 38.0 +/- 10.4 vs 64.0 +/- 14.4 mU/l). The combined administration of ARG and GHRH led to GH levels (101 +/- 15.2 mU/l) higher than those observed after GHRH (P less than 0.025) or ARG alone (P less than 0.001) and overlapping with those recorded after combined PD and GHRH administration (111 +/- 22.4 mU/l). In the other seven subjects, ARG and PD administration induced a similar GH response either when administered alone (25.2 +/- 13.6 and 27.8 +/- 4.0 mU/l, respectively) or in combination (33.8 +/- 5.4 mU/l). In conclusion, our results show that in children ARG administration potentiates GHRH- but not PD-induced GH increase. These findings agree with the hypothesis that the GH-releasing effect of both ARG and PD is mediated via the same mechanism, namely, by suppression of endogeneous somatostatin release. Combined administration of either ARG or PD with GHRH has a similar striking GH-releasing effect which is clearly higher than that of GHRH alone.
Ghigo
E
E
Department of Clinical Physiopathology, University of Turin, Italy.
Bellone
J
J
Mazza
E
E
Imperiale
E
E
Procopio
M
M
Valente
F
F
Lala
R
R
De Sanctis
C
C
Camanni
F
F
D000293:Adolescent; D001120:Arginine / Q000494:pharmacology*; D001827:Body Height / Q000187:drug effects / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D004357:Drug Synergism; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011729:Pyridostigmine Bromide / Q000494:pharmacology*; D011863:Radioimmunoassay; D013004:Somatostatin / Q000037:antagonists & inhibitors*
D013004:Somatostatin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine; D011729:Pyridostigmine Bromide