Effect of L-arginine on the course of experimental colitis

• Published in: Clinical nutrition (Edinburgh, Scotland) Vol. 20; no. 5; pp. 415 - 422
• Main Authors: MAÑÉ, J., FERNÁNDEZ-BAÑARES, F., OJANGUREN, I., CASTELLÁ, E., BERTRÁN, X., BARTOLÍ, R., ALVAREZ, M., GASSULL, M.A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2001; Elsevier
• Subjects: Acute Disease; Animals; Arginine - administration & dosage; Arginine - metabolism; Biological and medical sciences; Body Weight - drug effects; Chronic Disease; Colitis - chemically induced; Colitis - pathology; collagen; Collagen - biosynthesis; Colon - pathology; Disease Models, Animal; experimental colitis; Female; Fibrosis; Gastroenterology. Liver. Pancreas. Abdomen; Inflammation; Intestinal Mucosa - pathology; L-Arginine; Liver. Biliary tract. Portal circulation. Exocrine pancreas; Medical sciences; nitric oxide; Nitric Oxide - metabolism; Other diseases. Semiology; Random Allocation; Rats; Rats, Sprague-Dawley; Time Factors; L-Arginine; collagen; nitric oxide; experimental colitis; fibrosis; Animal model; Pathophysiology; Rat; Rodentia; Inflammation; Metabolism; Vertebrata; Mammalia; L-aminoacid; Arginine; Animal; Nitric oxide; Collagen; Fibrosis; Digestive diseases; Intestinal disease; Colitis
• ISSN: 0261-5614; 1532-1983
• DOI: 10.1054/clnu.2001.0469

Background and aims: L-Arg is the substrate for nitric oxide, and also for L-ornithine which, in turn, is the precursor for the synthesis of collagen and polyamines. By these different metabolic pathways, L-Arg is involved in the mechanisms of inflammation, tissue repair and fibrosis. Thus, the aim of this study was to assess the effect of both different amounts of L-Arg supplementation and L-Arg-free diets upon colonic inflammatory damage and fibrosis in experimental colitis. Methods: Sprague–Dawley rats with trinitrobenzene sulphonic acid (TNBS)-induced colitis received increasing doses of L-Arg (30, 100, 500 mg/day), or D-Arg (500 mg/day). In a second experiment, two L-Arg-free diets (one supplemented with L-Gly) were compared to a L-Arg diet. Nitrite/nitrate release in the lumen of the colon and colonic damage were evaluated. In the first experiment, tissue collagen levels and colonic mucosal proliferation were also assessed. Results: In the acute phase of colitis, intracolonic nitrite/nitrate levels were significantly higher in the 100 and 500 mg supplemented L-Arg groups than in D-Arg group. However, only rats treated with 500 mg of L-Arg showed moderately higher inflammatory and fibrosis colonic scores than the D-Arg treated rats. There was no significant influence of L-Arg-free diets on the course of TNBS-induced colitis. However, L-Arg diet accelerated weight gain both pre- and post-TNBS. Conclusions: These results suggest that normal amounts of L-Arg in the diet are not harmful, whereas both absence of L-Arg or supplementation with high doses of this amino acid may be deleterious. In the former this might be due to a decrease of nitrogen retention in injured rats, whereas in the latter it may result from both nitric oxide-mediated tissue damage and collagen deposition.