Tryptophan-niacin metabolism in rat with puromycin aminonucleoside-induced nephrosis.
We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidney alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.
Egashira
Yukari
Y
Laboratory of Food and Nutrition, Graduate School of Science and Technology, Chiba University, 648 Matsudo, Matsudo-shi, Chiba 271-8510, Japan. egashira@faculty.chiba-u.jp
Nagaki
Shin
S
Sanada
Hiroo
H
D000818:Animals; D002262:Carboxy-Lyases / Q000378:metabolism; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000737:chemistry; D008297:Male; D009243:NAD / Q000032:analysis / Q000097:blood; D009401:Nephrosis / Q000139:chemically induced* / Q000378:metabolism*; D009525:Niacin / Q000378:metabolism*; D009536:Niacinamide / Q000652:urine; D011692:Puromycin Aminonucleoside; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000032:analysis; D014364:Tryptophan / Q000097:blood / Q000378:metabolism*; D015430:Weight Gain
D012709:Serum Albumin; D009243:NAD; D009536:Niacinamide; D009525:Niacin; D011692:Puromycin Aminonucleoside; D014364:Tryptophan; D002262:Carboxy-Lyases; C024396:aminocarboxymuconate-semialdehyde decarboxylase