Investigation of the Memory Impairment in Rats Fed with Oxidized-Cholesterol-Rich Diet Employing Passive Avoidance Test

Abstract

Recent studies have shown that hypercholesterolemia, besides being a risk factor for cardiovascular diseases, has also toxic effects on central nervous system. The design of the present study was to investigate the effects of dietary cholesterol and oxidized cholesterol on cognitive function. Male Wistar rats were randomly divided into 3 groups. The animals were fed with three normal, 2% cholesterol-rich, and 2% oxidized cholesterol-rich diets for 14 weeks. Memory impairment was analyzed by passive avoidance test. Coenzyme Q10 content was also measured by a validate RP-HPLC method. Besides, lipid peroxidation in serum and brain tissue was determined by malondialdehyde concentration measurement. The results showed that feeding rats with high oxidized cholesterol diet for 14 weeks significantly impaired the cognitive function compared to the normal (P<0.001) and high cholesterol-fed groups (P<0.01). The memory impairment was positively correlated to the serum level of the oxidized LDL; it was significantly associated with the increased malondialdehyde concentration on the brain tissue of both groups (P<0.05 and P<0.001, respectively). The total antioxidant level in the serum was also decreased in rats fed with the oxidized cholesterol (P<0.05). Moreover, the brain coenzyme Q10 content was significantly declined in the animals fed with the oxidized cholesterol-rich diet compared to the animals fed with the normal (P<0.01) and cholesterol-rich diets (P<0.05). The results suggested that the high dietary intake of the oxidized-cholesterol might impair the memory that could be correlated to the oxidative stress and declined the coenzyme Q10 content of the brain tissue.