Impact of purine nucleotide on fatty acid metabolism and expression of lipid metabolism-related gene in the liver cell of rainbow trout Oncorhynchus mykiss

Studies have suggested that dietary purine nucleotides (NT) affect the muscle and liver fatty acid composition of rainbow trout. To examine the direct regulation of liver fatty acid metabolism by purine NT in rainbow trout, the liver cells were cultured in the presence of 500 μmol/L inosine, adenosine, or guanosine monophosphate (IMP, AMP, or GMP). The expression of pparα was significantly decreased in the liver cells cultured with purine NT for 24 h, whereas the expression of fads2 (Δ5) was increased. Docosahexaenoic acid (DHA) content in the liver cells was significantly higher after culturing with GMP. To determine the dose-dependent effects of NT, 50, 100, and 500 μmol/L GMP was added to the liver cells cultured in L-15 medium. At 48 h, 20:4n - 6, 22:5n - 3, 22:6n - 3, Ʃ PUFA, and Ʃ n - 3 PUFA content in the 50 μM GMP-containing medium was significantly higher compared with the other medium. The expression of Δ5 fads2, elovl2, and elovl5 in the liver cells was significantly higher in the 500 μmol/L GMP-containing medium at 48 h along with increased srebp-1 expression. These results suggest that purine NT directly affect fatty acid composition through modification of fatty acid metabolism-related genes in the liver of rainbow trout.