Oral amino acid administration decreases oxidative stress and improves brachial reactivity in elderly individuals.
BACKGROUND
Atherosclerosis is a major cause of death in elderly individuals. Endothelial dysfunction is recognized as a key early event in atherogenesis. In the present study, we evaluated the possible beneficial effect of amino acid administration on endothelial regulation in elderly subjects.


METHODS
A total of 25 healthy elderly subjects were administered essential amino acids (EAA) for 4 months. Before and after EAA administration, each subject underwent brachial reactivity investigation with and without an intra-arterial infusion of 4 micromol/min of N(G)-monomethyl-l-arginine (L-NMMA), an inhibitor of nitric oxide (NO) synthase.


RESULTS
At baseline, age correlated with free plasma insulin growth factor-1 IGF-1 (r = -0.48; P < .01), plasma Trolox equivalent antioxidant capacity (TEAC) (r = -0.40; P < .04), and thiobarbituric acid-reactive substances (TBARS) (r = 0.42, P < .04), and homeostasis model assessment (HOMA) index (r = 0.45, P < .03), as well as with changes in diameter (r = -0.49, P < .01) and flow (r = -0.43, P < .03). Administration of EAA was associated with a significant increase in plasma TEAC (P < .001) and decline in plasma TBARS (P < .001) and with improvement in changes in diameter (7.15 +/-1.10 v 8.98 +/-1.80, P < .001) and flow (5.6 +/-1.2 v 6.4 +/- 1.2, P < .03). These latter two associations were independent of changes in HOMA index (P < .04 for both correlations). The beneficial effects of EAA administration on brachial reactivity were partly attenuated by L-NMMA.


CONCLUSIONS
Administration of EAA may improve brachial reactivity in elderly persons and may also protect against the development of atherosclerosis via the rise in plasma-free IGF-1 levels.
Manzella
Daniela
D
Department of Geriatric Medicine and Metabolic Diseases, II University of Naples, Naples, Italy.
Grella
Rodolfo
R
Esposito
Katherine
K
Cacciapuoti
Federico
F
Arciello
Alessandro
A
Giugliano
Dario
D
Paolisso
Giuseppe
G
D000284:Administration, Oral; D000368:Aged; D000601:Amino Acids, Essential / Q000008:administration & dosage*; D000975:Antioxidants / Q000378:metabolism; D001783:Blood Flow Velocity / Q000187:drug effects* / Q000502:physiology; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology*; D002839:Chromans / Q000097:blood; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007261:Infusions, Intra-Arterial; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D015588:Observer Variation; D018384:Oxidative Stress / Q000187:drug effects*; D011863:Radioimmunoassay; D012016:Reference Values; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014463:Ultrasonography; D019323:omega-N-Methylarginine / Q000008:administration & dosage
D000601:Amino Acids, Essential; D000975:Antioxidants; D002839:Chromans; D004791:Enzyme Inhibitors; D017392:Thiobarbituric Acid Reactive Substances; D019323:omega-N-Methylarginine; D007334:Insulin-Like Growth Factor I; D019001:Nitric Oxide Synthase; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid