Change of tryptophan-niacin metabolism in D-galactosamine-induced liver injury in rat.
The change of tryptophan-niacin metabolism in D-galactosamine (D-galN) injected rats was investigated. Rats fed with niacin-free diets containing 40% casein for 11 days were injected with D-galN (0.8 g/kg body weight). The urinary excretions of nicotinamide and its metabolites, and the activity of liver alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) (EC 4.1.1.45), a key enzyme of tryptophan-niacin metabolism, were assayed. As the result, the urinary excretions of N1-methylnicotinamide (MNA), N1-methyl-2-pyridone-5-carboxamide (2-Py), N1-methyl-4-pyridone-3-carboxamide (4-Py) and their sum (nicotinamide+MNA+2-Py+4-Py) were higher in the D-galN-injected group than in the control group. Hepatic ACMSD activity in the D-galN-injected group was lower than that of the control group. These results suggest that the increase in urinary excretion of nicotinamide and its metabolites after the injection of D-galN is considered to be attributable to a decrease in liver ACMSD activity.
Egashira
Y
Y
Department of Bioproduction Science, Faculty of Horticulture, Chiba University, Matsudo, Japan.
Komine
T
T
Ohta
T
T
Shibata
K
K
Sanada
H
H
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D002262:Carboxy-Lyases / Q000378:metabolism; D005688:Galactosamine / Q000633:toxicity*; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000293:injuries; D008297:Male; D009525:Niacin / Q000378:metabolism*; D009536:Niacinamide / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000378:metabolism*; D014366:Tryptophan Oxygenase / Q000378:metabolism
D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D009536:Niacinamide; D009525:Niacin; D005688:Galactosamine; D014364:Tryptophan; D014366:Tryptophan Oxygenase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D002262:Carboxy-Lyases; C024396:aminocarboxymuconate-semialdehyde decarboxylase