Int J Vitam Nutr Res. 2006 Jan;76(1):28-33Tryptophan-niacin
metabolism in rat with puromycin aminonucleoside-induced
nephrosis.
Egashira Y, Nagaki S, Sanada H.
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
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.
PMID: 16711654 |
