The kynurenine pathway enzymes in healthy and hyperlipidemic rabbits.
Tryptophan metabolism along the kynurenine pathway in normolipidemic and diet-induced hyperlipidemic New Zealand rabbits was studied. The activities of liver tryptophan 2,3-dioxygenase small intestine indole 2,3-dioxygenase, liver and kidney kynurenine 3-monooxygenase, kynurenine-oxoglutarate transaminase, kynureninase, 3-hydroxyanthranilate 3,4-dioxygenase and aminocarboxymuconate semialdehyde decarboxylase (picolinic carboxylase) were determined. Liver tryptophan 2,3-dioxygenase (TDO) was present only as a holoenzyme. In fact, similar results were found in the absence or presence of the cofactor haematin. In addition, TDO activity was higher in normolipidemic than in hyperlipidemic rabbits. Small intestine indole 2,3-dioxygenase did not change significantly among the two groups of animals, but was higher than liver TDO. Liver and kidney kynurenine 3-monooxygenase activities did not change significantly whereas kynurenine-oxoglutarate transaminase activity decreased only per g of fresh kidney in hyperlipidemic rabbits. Kynureninase activity decreased significantly per g of fresh tissue only in liver. 3-Hydroxyanthranilate 3,4-dioxygenase, both as specific activity and per g of fresh tissue and aminocarboxymuconate-semialdehyde decarboxylase activities showed significantly lower values per g of fresh kidney in hyperlipidemic rabbits compared with controls. Therefore, hyperlipidemia can influence enzyme activities along the kynurenine pathway, leading to a reduction in the biosynthesis of NAD coenzymes.
Allegri
Graziella
G
Department of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, I-35131 Padova, Italy. graziella.allegri@unipd.it
Ragazzi
Eugenio
E
Costa
Carlo V L
CV
Caparrotta
Laura
L
Biasiolo
Monica
M
Vanin
Silvia
S
D000818:Animals; D006949:Hyperlipidemias / Q000201:enzymology / Q000378:metabolism*; D007421:Intestine, Small / Q000201:enzymology; D007668:Kidney / Q000201:enzymology; D007737:Kynurenine / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008297:Male; D011817:Rabbits; D014364:Tryptophan / Q000378:metabolism; D014366:Tryptophan Oxygenase / Q000378:metabolism
D007737:Kynurenine; D014364:Tryptophan; D014366:Tryptophan Oxygenase