Long-term consumption of a methionine-supplemented diet increases iron and lipid peroxide levels in rat liver.
Methionine is a protective factor against various types of liver damage, but excessive dietary methionine is hepatotoxic. Because the mechanisms of L-methionine-related hepatotoxicity are poorly understood, the effect of long-term excessive L-methionine intake on the metabolism of iron and antioxidants was studied in rat liver to determine whether oxidative stress is involved. Wistar male rats were fed either an L-methionine-supplemented (16.0 g/kg) diet or a control diet for 1, 3, 6 and 9 mo. The growth rate of L-methionine-supplemented rats was significantly slower than that of controls. Iron, ferritin and thiobarbituric acid-reactive substances (TBARS) levels in the liver were greater in supplemented rats than in controls. Serum iron and transferrin levels were significantly lower in L-methionine-treated rats compared with controls. Serum ferritin did not differ between the two groups. Hepatic glutathione peroxidase activity, catalase activity and total glutathione concentrations were higher in rats fed the L-methionine-supplemented diet at 1 and 3 mo, but not at 6 and 9 mo. These results indicate that long-term consumption of excess L-methionine by rats may affect primarily iron metabolism rather than the antioxidant defense system and, consequently, induce an accumulation of iron.
Mori
N
N
College of Medical Science, Kumamoto University, 4-24-1 Kuhonji, Kumamoto 862-0976, Japan.
Hirayama
K
K
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002374:Catalase / Q000378:metabolism; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005293:Ferritins / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D007501:Iron / Q000097:blood / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D000975:Antioxidants; D017392:Thiobarbituric Acid Reactive Substances; D005293:Ferritins; D008715:Methionine; D007501:Iron; D002374:Catalase; D005979:Glutathione Peroxidase