Biochemical and histopathological effects of dietary oxidized cholesterol products in rats

Cholesterol is present in a great variety of foods of animal origin. Oxidation of this substance produces cholesterol oxidation products (COP´s) that have been associated with the genesis of chronic degenerative diseases such as atherosclerosis. This chronic disease is characterized by histological changes that reflect damage to the arterial structure because of accumulation of lipids that contain oxidized cholesterol in the form of an oxidized low density lipoprotein. The purpose of this work was to study the biochemical and histological effect of dietary COP´s in rats. Male Wistar albino rats (5 weeks old) were obtained from Harlan (Mexico City); the animals were randomly divided into three groups of ten rats each. Standard rat chow was supplemented with either 1% (w/w) pure cholesterol or 1% oxidized cholesterol and fed to rats for 8 weeks. Control animals were fed standard rat chow. At the end of 8 weeks, the lipid profile was determined in serum; the aorta, liver and kidneys were excised immediately, frozen with liquid nitrogen, and held at -56°C. The histological study was carried out using conventional hematoxilin – eosin and Oil Red O techniques. The administration of dietary COP´s altered those biochemical parameters involved in lipid metabolism that are associated with atherogenesis in rats, namely, total cholesterol, triglycerides, and low density lipoproteins. The COP´s modified the tissue structure of the aorta where the presence of lipids was demonstrated in the inner coat; in the liver and kidney, COPs caused infiltration of lymphocytes, fibrosis and steatosis. Further investigations will provide information regarding the consumption of dietary COP´s, their implications in oxidative stress, and their participation as gene regulators.