Acute amino acids supplementation enhances pituitary responsiveness in athletes.
OBJECTIVE
The purpose of this study was to determine the effect of a mixture of amino acids on pituitary responsiveness to a stimulation test (GnRH + CRH) in athletes.


METHODS
In a double blinded counterbalanced experimental protocol, 10 moderately trained male athletes performed the pituitary stimulation test 60 min after a single oral administration of a placebo (P1-AS) or an amino acid mixture solution (AS) (L-arginine hydrochloride 100 mg x kg(-1) + L-ornithine hydrochloride 80 mg x kg(-1) + L-branched chain amino acids 140 mg x kg(-1): 50% L-leucine, 25% L-isoleucine, 25% L-valine) on two different occasions. Plasma ACTH, LH, FSH, GH, and cortisol were evaluated before (-60, -30, 0 min) and after (+15, +30, +45, +60, +90 min) the stimulation test.


RESULTS
The ACTH, LH and FSH response to CRH + GnRH was significantly higher in AS group both as absolute values and area under curve (AUC) values than in P1-AS group. Pre-test and post-test cortisol AUC levels were significantly higher in P1-AS group although a higher percent increase in post-test cortisol was found in AS group. The total GH-AUC was higher in AS group and, as expected, the absolute GH concentrations at different time points were not influenced by CRH + GnRH administration.


CONCLUSIONS
The amino acid mixture used enhanced the ACTH, LH, and FSH response to CRH + GnRH.
di Luigi
L
L
Endocrine Research Laboratory, Sports Medicine Unit, University Institute of Motor Sciences, Rome, Italy.
Guidetti
L
L
Pigozzi
F
F
Baldari
C
C
Casini
A
A
Nordio
M
M
Romanelli
F
F
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage*; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D019587:Dietary Supplements; D005640:Follicle Stimulating Hormone / Q000097:blood; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D010902:Pituitary Gland / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000187:drug effects; D013177:Sports / Q000502:physiology*
D000596:Amino Acids; D019382:Human Growth Hormone; D000324:Adrenocorticotropic Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D003346:Corticotropin-Releasing Hormone; D006854:Hydrocortisone