Impact of carotid atherosclerosis combined with hypercholesterolemia on cerebral microvessels and brain parenchyma in a new complex rat model

摘要

Most previous investigations about stroke caused by carotid atherosclerosis have focused on thromboembolism. There is a lack of knowledge about pathophysiology of the brain before ischemic insults. The objective of this study was to develop a new model of hypercholesterolemia plus carotid injury and to investigate the impact of carotid atherosclerosis combined with hypercholesterolemia in the rat brain. The complex rat model was developed by carotid injury induced by an air-drying endothelial denudation method after high cholesterol diet for 2 weeks. Plasma cholesterol, carotid pathomorphology, oxidative stress and inflammation in cerebral microvessels and brain parenchyma were measured at 7, 14 and 28 days after carotid surgery. The results showed that plasma concentrations of total cholesterol and low density lipoprotein-cholesterol were significantly increased, and severe carotid atherosclerosis and stenosis was observed in the complex rat model at 14 and 28 days after carotid surgery. The activity of superoxide dismutase was decreased, while the content of malondialdehyde was increased in cerebral microvessels and brain parenchyma. The levels of tumor necrosis factor-α and interleukin-1β were elevated in brain tissues of this model. Almost all above changes were more severe than those in either hypercholesterolemia alone group or carotid injury alone group. These results suggest that this complex rat model may more resemble human disease than the classic acute ischemic insult model for assessing the impact of carotid atherosclerosis as a preexisting disease on cerebral microcirculation and brain tissue.