Endocrine and lipid effects of oral L-arginine treatment in healthy postmenopausal women.
As a substrate for nitric oxide synthesis, L-arginine may give the same protection as estrogen, but its other biologic effects may adversely affect atherogenesis. Therefore, possible endocrine and lipid effects of L-arginine were investigated in a double-blind, placebo-controlled, single crossover study. After randomization, oral L-arginine (9 g) or placebo was given daily for 1 month, with crossover to the alternate therapy after a 1-month washout period, to 10 postmenopausal women receiving no estrogen. Compared with placebo, L-arginine increased growth hormone (1.5+/-1.8 mg/L vs. 0.6+/-0.6 mg/L, P = .04) but had no effect on insulin and catecholamines. Total cholesterol, triglyceride, apolipoprotein E, and low-, very-low-, and high-density lipoprotein cholesterol levels were also unaffected. Lipoprotein(a) measured by an immunoturbidimetric method was increased by L-arginine in 9 of 10 women relative to placebo (0.46+/-0.35 g/L vs. 0.38+/-0.30 g/L, P = .053), and the changes in lipoprotein(a) levels significantly correlated with the relative increase in growth hormone (r = 0.85, P = .03). However, lipoprotein(a) measured by an enzyme-linked immunosorbent assay failed to demonstrate significant changes. Lack of an increase by L-arginine in lipoprotein(a) with a verifiable apolipoprotein(a) isoform-independent method, despite an increase in growth hormone, questions the validity of previous observations for growth hormone-induced increases in lipoprotein(a). The observed lack of effect on major endocrine hormones and lipid profile support the safety of oral L-arginine administration.
Blum
A
A
Clinical Pathology Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892-1508, USA.
Cannon
R O
RO
Costello
R
R
Schenke
W H
WH
Csako
G
G
D000284:Administration, Oral; D001120:Arginine / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D004311:Double-Blind Method; D004702:Endocrine Glands / Q000187:drug effects*; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D008055:Lipids / Q000097:blood*; D017270:Lipoprotein(a) / Q000097:blood; D008593:Menopause; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood; D012449:Safety
D008055:Lipids; D017270:Lipoprotein(a); D017395:Plasminogen Activator Inhibitor 1; D019382:Human Growth Hormone; D009569:Nitric Oxide; D001120:Arginine