Difference and Similarity of Serotonin and Pteridines to Act on Lipid Metabolism

Abstract

Incorporation of fatty acids into phospholipids has been investigated using samples of rat liver homogenate, Krebs-Ringer phosphate buffer (pH=7.4) containing 0.3% albumin, fatty acid mixture and glycerol. The addition of neopterin, serotonin (0.2 and 2.0 nmoljg wet weight) without iproniasid and 5- hydroxyindoleacetic acid (20.0 nmoljg wet weight) induced an increase of saturated and a decrease of unsaturated, especially arachidonic acid, incorporation into phospholipids. These changes were accompanied with elevated cholesterol content in samples. The addition of 5,6,7,8-tetrahydrobiopterin (5 and 30 pmolj g wet weight) and serotonin (0.2 and 2.0 nmoljg wet weight) together with iproniasid (10 nmoljg wet weight) to incubation medium for phospholipid biosynthesis in vitro induced a decrease of saturated and an increase of unsaturated, especially arachidonic acid, incorporation into phospholipids. These changes were accompanied with decreased cholesterol content in samples. The influence of serotonin without iproniasid and 5-hydroxyindoleacetic acid was similar to that of neopterin, kynurenine and noradrenaline observed earlier, while the influence of serotonin together with iproniasid was similar to that of 5,6,7,8- tetrahydrobiopterin and its precursors found earlier. Our results allow to suggest that in the studied concentrations serotonin increases, while 5-hydroxyindoleacetic acid decreases membrane fluidity.

Keywords

• neopterin
• tetrahydrobiopterin
• serotonin
• 5-hydroxyindoleacetic acid
• fatty acids
• phospholipids
• cholesterol