Endocrinology, Vol 108, 331-335, Copyright © 1981 by Endocrine Society

ARTICLES

L-Tryptophan injection enhances pulsatile growth hormone secretion in the rat

MA Arnold and JD Fernstrom

The effect of injecting L-tryptophan or a serotonin receptor agonist [6- Cl-2-[1-piperazinyl]pyrazine ((MK0212)] on pulsatile GH secretion was studied in male rats bearing right atrial cannulae. After injection, blood samples were drawn at 15-min intervals for periods up to 4 h. L- Tryptophan administration (50 or 100 mg/kg, ip) significantly enhanced mean plasma GH levels measured over a 3.5-h period. Injection of another large neutral amino acid, L-valine (100 mg/kg, ip), did not influence plasma GH levels. However, when administered with tryptophan, valine blocked the tryptophan-induced enhancement of GH secretion and blunted the increases in brain tryptophan and serotonin levels that normally accompany tryptophan injection. Injection of MK-212 (2 mg/kg, ip) elicited an immediate rise in plasma GH levels; this effect was completely blocked by pretreatment with metergoline (2 mg/kg, ip), a serotonin receptor antagonist. Taken together, these data support the notion that treatments which increase serotonin receptor stimulation enhance or induce pulsatile GH secretion.

This article has been cited by other articles:

				J. D. Fernstrom Branched-Chain Amino Acids and Brain Function J. Nutr., June 1, 2005; 135(6): 1539S - 1546S. [Abstract] [Full Text] [PDF]

				E. E. Muller, V. Locatelli, and D. Cocchi Neuroendocrine Control of Growth Hormone Secretion Physiol Rev, April 1, 1999; 79(2): 511 - 607. [Abstract] [Full Text] [PDF]