Effects of fish oil on phospholipid metabolism in human and rat liver studied by 31 P NMR spectroscopy in vivo and in vitro

The effect of ω3 fatty acids on the metabolism of the normal liver was studied using 31 P NMR spectroscopy. Human subjects were examined before and after 1, 3 and 7 days of supplementation with 50 mL fish oil per day (12 g ω3 fatty acids). 31 P NMR spectra (1.6 T) revealed a significant increase in phosphodiester (PDE) to ATP ratios after 1 and 3 days of fish oil. After 7 days, [PDE]/[ATP] ratios at a TR of 1 s had returned to baseline levels, but [PDE]/[ATP] at a TR of 5 s appeared to remain high. Rats were fed diets containing 50% of the energy from fish oil or normal rat chow (controls) for 14 days. 31 P NMR liver spectra in vivo (4.7 T) confirmed increased [PDE]/[ATP] in rats fed fish oil compared to controls, although the difference was only statistically significant at a TR of 1.5 s but not at a TR of 8s. 31 P NMR spectra of rat liver extracts (8.7 T) suggested that increased concentrations of glycerophosphocoline and possibly glycerophosphoethanolamine were responsible for rising PDE levels in vivo . Phosphocholine (PC) concentrations were markedly reduced in rat liver after fish oil. The combined rise in glycerophosphocholine and reduction in PC would be consistent with a shift from the phospholipase C to the phospholipase A1/A2 pathway of phosphatidylcholine breakdown after fish oil consumption.