Palmitate protects hepatocytes from oxidative stress and triacylglyceride accumulation by stimulation of nitric oxide synthesis in the presence of high glucose and insulin concentration

Abstract

Excessive flux of free fatty acids (FFA) into the liver contributes to liver impairment in non-alcoholic fatty liver disease (NAFLD). It remains unclear how FFA contribute to impairment of hepatocytes. This study treated hepatocytes with linoleic acid and palmitate to investigate the early event triggering FFA-mediated impairment. It determined cell viability, content of nitrite/nitrate and triacylglycerides (TG), inducible nitric oxide synthase (iNOS) protein, oxidation of cardiolipin (CL) as well as formation of F₂-isoprostanes in the presence of insulin and glucose. Linoleic acid caused significant decrease in cell viability. It is shown that palmitate caused induction of iNOS resulting in increased nitrite/nitrate concentration and slight increase in TG content. Linoleic acid led to a decrease in nitrite/nitrate concentration parallelled by massive TG accumulation in combination with increased oxidation of CL and increased F₂-isoprostane levels. It is concluded that nitric oxide (NO) concentration regulates FFA-dependent TG accumulation and oxidative stress in rat hepatocytes.

Keywords::

• Adult hepatocyte culture
• linoleic acid
• palmitate
• nitric oxide
• lipid accumulation
• oxidized cardiolipin
• F₂-isoprostanes

Acknowledgements

We are grateful to Mrs Heidemarie Faber, Mrs Silke Niemann, Mrs Leona Bück and Mrs Heike Baumann for skillful technical assistance. We also thank Mrs Eva Gittel for providing the TG data. This study was supported by COST action B 35.

Declaration of interest: This study was supported by COST action B 35.

This paper was first published online on Early Online on 27 August 2010.