A hyperlipidemic diet induces structural changes in cerebral blood vessels.

Abstract

The cerebrovascular pathology is an important contributor to the death rate presently. Hyperlipidemia , an established risk factor for cardiovascular diseases, is also incriminated in the neurodegenerative disorders. The aim of this study was to evaluate the effect of a hyperlipidemic (HL) diet on the morphology of the cerebral vessels and on the amyloid deposition in the HL hamster, an accepted model of atherosclerosis. Hamsters fed a HL diet were tested periodically for serum parameters and sacrificed after 3 and 6 months. The methods used were: paraffin embedding, thioflavin S amyloid staining, fluorescence and electron microscopy (EM). Increased serum cholesterol and triglycerides characterized the HL hamsters. The carotid arteries developed fatty streaks after 3 months and atherosclerotic plaques after 6 months HL diet. The brain cortex comprised irregularly shaped microvessels with large perivascular spaces, enlarged endothelial cells (EC) and occasionally a lumen full of lipoprotein particles. The thioflavin S reaction revealed a discreet staining of the capillaries walls; the EC cytoplasm and basal lamina contained a fibrillar material, with a pattern similar to an incipient amyloid deposit. Some large meningeal vessels from animals with serum cholesterol over 1000 mg/dl presented an intense autofluorescence in the adventitia; EM examination identified lipid-loaded perivascular cells in these areas. In conclusion, the detected morphological changes induced by the HL diet could represent a serious impairment for the normal brain function. These data may contribute to the better understanding of the risks of hyperlipidemia for the mental health, and its reversal could become a new therapeutic approach for neurodegenerative disorders.