Of the amino acids arginine is the most potent GH secretagogue in man. It potentiates the GH response to GHRH, exerts a weaker PRL-releasing effect, stimulates insulin and glucagon and induces a biphasic glucose variation. The potency and effects of other amino acids on pituitary and pancreatic hormones need to be clarified. In 43 children with normal short stature (5.3-14.0 yr; 30 M and 13 F) the effects of the infusion of phenylalanine (Phe, 0.08 g/kg), histidine (His, 0.1 g/kg), and leucine (Leu, 0.08 g/kg) on basal and GHRH-stimulated GH secretion and on PRL, insulin and glucose levels were studied and compared with those of arginine at high (hArg, 0.5 g/kg) or low dose (lArg, 0.2 g/kg). Phe increased basal (p < 0.05) but not GHRH-stimulated GH levels, induced PRL and insulin rises (p < 0.03 and p < 0.03), and did not change glycemia. Though a trend toward an increase in basal GH levels was found after His, His and Leu did not significantly modify either basal or GHRH-induced GH secretion nor basal PRL, insulin and glucose levels. Both hArg and lArg increased basal (p < 0.0001 and p < 0.05, respectively) and GHRH-stimulated GH levels (p < 0.006 and p < 0.006). hArg increased both PRL (p < 0.002) and insulin levels (p < 0.005) more (p < 0.0005 and p < 0.004) than lArg (p < 0.005 and p < 0.005), while glucose levels showed a similar increase followed by a similar decrease. We conclude that in childhood: a) Phe significantly increases GH secretion but, differently from Arg, does not potentiate the response to GHRH, suggesting different mechanisms of action of these amino acids; b) differently from His and Leu, Phe is a PRL and insulin secretagogue but is less potent than Arg; c) Arg has the highest stimulatory effect on pituitary and pancreatic hormones.

Effects of phenylalanine, histidine, and leucine on basal and GHRH-stimulated GH secretion and on PRL, insulin, and glucose levels in short children. Comparison with the effects of arginine.

GHIGO, Ezio
1996-01-01

Abstract

Of the amino acids arginine is the most potent GH secretagogue in man. It potentiates the GH response to GHRH, exerts a weaker PRL-releasing effect, stimulates insulin and glucagon and induces a biphasic glucose variation. The potency and effects of other amino acids on pituitary and pancreatic hormones need to be clarified. In 43 children with normal short stature (5.3-14.0 yr; 30 M and 13 F) the effects of the infusion of phenylalanine (Phe, 0.08 g/kg), histidine (His, 0.1 g/kg), and leucine (Leu, 0.08 g/kg) on basal and GHRH-stimulated GH secretion and on PRL, insulin and glucose levels were studied and compared with those of arginine at high (hArg, 0.5 g/kg) or low dose (lArg, 0.2 g/kg). Phe increased basal (p < 0.05) but not GHRH-stimulated GH levels, induced PRL and insulin rises (p < 0.03 and p < 0.03), and did not change glycemia. Though a trend toward an increase in basal GH levels was found after His, His and Leu did not significantly modify either basal or GHRH-induced GH secretion nor basal PRL, insulin and glucose levels. Both hArg and lArg increased basal (p < 0.0001 and p < 0.05, respectively) and GHRH-stimulated GH levels (p < 0.006 and p < 0.006). hArg increased both PRL (p < 0.002) and insulin levels (p < 0.005) more (p < 0.0005 and p < 0.004) than lArg (p < 0.005 and p < 0.005), while glucose levels showed a similar increase followed by a similar decrease. We conclude that in childhood: a) Phe significantly increases GH secretion but, differently from Arg, does not potentiate the response to GHRH, suggesting different mechanisms of action of these amino acids; b) differently from His and Leu, Phe is a PRL and insulin secretagogue but is less potent than Arg; c) Arg has the highest stimulatory effect on pituitary and pancreatic hormones.
1996
9
523
531
BELLONE J ;VALETTO MR ;AIMARETTI G ;SEGNI M ;VOLTA C ;CARDIMALE G ;BAFFONI C ;PASQUINO AM ;BERNASCONI S ;BARTOLOTTA E ;MUCCI M ;GHIGO E
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/33245
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