The Influence of Kynurenine and Its Metabolites on Lipid Metabolism

Abstract

Incorporation of fatty acids into phospholipids has been investigated using samples of rat liver tissue homogenate, Krebs-Ringer-phosphate buffer (pH=7.4) containing 0.3% albumin, fatty acid mixture and glycerol. The addition of L-kynurenine (4 nmoljg wet weight) to incubation medium induced an increase of palmitic, oleic and linolenic acid and decrease of linoleic and arachidonic acid incorporation into phospholipids. These changes of fatty acid incorporation into phospholipids were followed by increase of cholesterol and decrease of phospholipids content in samples. The addition of 3-hydroxykynurenine (1.8 and 4 nmoljg wet weight), 3-hydroxyanthranilic acid (2.2 and 4 nmoljg wet weight) ,1n..:l quinolinic acid (2.4 and 4 nmoljg wet weight) to incubation medium for phospholipid biosynthesis ill vitro induced a decrease of stearic, palrnitic and linoleic acid and an increase of oleic and especially arachidonic acid incorporation into phospholipids. These changes were accompanied by a decrease of cholesterol content in samples. The influence of kynurenine on fatty acid incorporation into phospholipids was similar to that of neopterin observed earlier. The other tryptophan degradation products behaved similar to the reduced pteridine derivatives. Our results allow to suggest that L-kynurenine decreases, while 3-hydroxykynurenine, 3-hydroxyanthranilic acid and quinolinic acid increase membrane fluidity in the studied concentrations.

Keywords

• kynurenine
• 3-hydroxykynurenine
• 3-hydroxyanthranilic acid and quinolinic acid
• fatty acids
• phospholipids
• cholesterol