Fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually not found in organisms, but instead as three main classes of esters: triglycerides, phospholipids, and cholesterol esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and they are important structural components for cells.
Lipotoxicity
An excess of free fatty acids in liver cells plays a role in Nonalcoholic Fatty Liver Disease (NAFLD). In the liver, it is the type of fatty acid, not the quantity, that determines the extent of the lipotoxic effects. In hepatocytes, the ratio of monounsaturated fatty acids and saturated fatty acids leads to apoptosis and liver damage. There are several potential mechanisms of by which the excess fatty acids can cause cell death and damage. They may activate death receptors, stimulate apoptotic pathways, or initiate cellular stress response in the endoplasmic reticulum. These lipotoxic effects have been shown to be prevented by the presence of excess triglycerides within the hepatocytes.
Lipotoxicity in cardiac tissue is attributed to excess saturated fatty acids. The apoptosis that follows is believed to be caused by unfolded protein response in the endoplasmic reticulum. Researchers are working on treatments that will increase the oxidation of these fatty acids within the heart in order to prevent the lipotoxic effects.