title: Dietary protein level and dietary interaction affect quinolinic acid concentration in rats.
abstract: During tryptophan-niacin conversion, hepatic alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) [EC4.1.1.45] plays a key role in regulating NAD biosynthesis. ACMSD activity is greatly affected by many factors such as nutritional status and disease. The tryptophan catabolite quinolinic acid has been reported to be associated with the pathogenesis of various disorders and is a potential endogenous toxin. However the effects of dietary protein levels or dietary interaction between protein levels and fatty acid type to this process have not been investigated and are still unknown. In this study, we examined whether dietary protein level, fatty acid type, namely saturated fatty acid and polyunsaturated fatty acid, and their interaction affect serum quinolinic acid concentration in rats. Male Sprague-Dawley rats (4-weeks old) were fed with 20% casein + 10% stearic acid diet (20C10S), 20% casein + 10% linoleic acid diet (20C10L), 40% casein + 10% stearic acid diet (40C10S), or 40% casein + 10% linoleic acid diet (40C10L) for 8 days, and serum quinolinic acid concentration and ACMSD activity were determined. Serum quinolinic acid concentration was significantly increased in the 40C10L group compared with other three groups. There was also the negative correlation between the sum of liver and kidney ACMSD activities, and serum quinolinic acid concentration per tryptophan intake (r = 0.8209, p < 0.01). Increased serum QA concentrations are probably due to a decreased ACMSD activity.
authors: Laboratory of Food and Nutrition, Graduate School of Science and Technology, Chiba University, Matsudo 271-8510, Japan. egashira@faculty.chiba-u.jp
authors: Yukari
authors: Y
authors: Egashira
authors: Mayuki
authors: M
authors: Sato
authors: Kuniaki
authors: K
authors: Saito
authors: Hiroo
authors: H
authors: Sanada
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002262:Carboxy-Lyases / Q000378:metabolism; D002364:Caseins / Q000008:administration & dosage / Q000494:pharmacology; D004032:Diet / Q000379:methods*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000494:pharmacology; D007668:Kidney / Q000201:enzymology; D019787:Linoleic Acid / Q000008:administration & dosage / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D008297:Male; D009929:Organ Size / Q000187:drug effects; D017378:Quinolinic Acid / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013229:Stearic Acids / Q000008:administration & dosage / Q000494:pharmacology; D014364:Tryptophan / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D002364:Caseins; D004044:Dietary Proteins; D005227:Fatty Acids; D013229:Stearic Acids; C031183:stearic acid; D014364:Tryptophan; D019787:Linoleic Acid; D002262:Carboxy-Lyases; C024396:aminocarboxymuconate-semialdehyde decarboxylase; D017378:Quinolinic Acid