Effect of 3-month L-arginine supplementation on insulin resistance and tumor necrosis factor activity in patients with visceral obesity.
BACKGROUND
The role of tumor necrosis factor alpha (TNF-alpha), one of the adipose tissue products, in the pathogenesis of insulin resistance is well-documented. Many recent studies have shown beneficial influence of L-arginine supplementation on cardiovascular system. However, molecular mechanisms of its positive actions are not fully elucidated.


OBJECTIVE
The aim of the study was to evaluate the influence of L-arginine supplementation on tumor necrosis factor alpha, insulin resistance and selected anthropometric and biochemical parameters in patients with visceral obesity.


METHODS
60 patients with visceral obesity were randomly assigned to either receive 9 g of L-arginine or placebo for 3 months. 20 healthy lean subjects were used as control. Selected anthropometrical measurements and blood biochemical analyses were performed at baseline and after 3-months. TNF-alpha and its soluble receptor 2 (sTNFR2) were assessed in both treated groups. Insulin resistance in the participants was evaluated according to the homeostasis model assessment-insulin resistance (HOMA-IR) protocol.


RESULTS
The concentration of insulin, TNF-a and sTNFR2 and HOMA-IR level in both obese groups significantly exceeded these observed in the control. Basal TNF-alpha and sTNFR2 concentrations were positively correlated with basal body mass index (BMI), waist circumference, percent of body fat and HOMA-IR. We found that 3-month L-arginine supplementation resulted in significant decrease of HOMA-IR and insulin concentration. Only insignificant tendency to decrease of TNF-alpha and sTNFR2 was observed.


CONCLUSIONS
Our results confirm TNF-alpha role in the complex pathogenesis of insulin resistance in patients with visceral obesity. 3-months L-arginine supplementation in a dose of 9 g improves insulin sensitivity in patients with visceral obesity with no impact on tumor necrosis factor alpha concentration.
Department of Internal Medicine, Metabolic Disorders and Hypertension, Poznan University of Medical Sciences, Poznan, Poland. pawelbogdanski@wp.pl
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P
Bogdanski
J
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Suliburska
K
K
Grabanska
K
K
Musialik
A
A
Cieslewicz
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A
Skoluda
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A
Jablecka
D000328:Adult; D001120:Arginine / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D056128:Obesity, Abdominal / Q000188:drug therapy* / Q000378:metabolism; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*
D007328:Insulin; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D001120:Arginine