Cerebral microvascular changes induced by rich cholesterol and saturated fatty acid diet in Wistar rats

The impact of an excess of fatty acids in the diet on cardiovascular diseases has been studied and discussed both in human and animal studies. Generally, excessive saturated fats increase the risk, while unsaturated fats are considered less harmful. Our aim was to perform an experimental study in order to analyze how fatty diet quality (unsaturated vs. saturated fatty acids) influences atherogenesis. Materials and Methods: In our experimental study, 18 adult Wistar rats were randomly divided into two equal groups. One group was subjected to a rich unsaturated fatty acid diet (untar) and the other group to a rich saturated one (palm oil). Three animals from each group were sacrificed after 12, 18, and 48 weeks. The brain was removed and microscopically examined after Hematoxylin-Eosin, Orcein and Masson's trichrome classical staining, and after immunohistochemical marking using the anti-alpha smooth muscle actin antibody. Results: Rats sacrificed after 12 weeks revealed modicum lesions, as intimal vacuoles or minute intraluminal thrombosis, and cerebral parenchymal edema. After 18 weeks, some of rats subjected to a rich saturated fatty acid diet presented vacuoles found in all arteriolar wall layers, and a tendency towards parietal thrombosis. In rats subjected to a rich unsaturated fatty acid diet, the subintimal arteriolar vacuolization was associated with an intramural and adventitial fibrosis. In rats sacrificed after 48 weeks, lesional polymorphism was pronounced, but in rats subjected to a rich unsaturated fatty acid diet complete luminal thrombosis was followed by a an organized thrombus with multiple capillary channels. Although in Wistar rats atherosclerosis appeared only after intensive changes in diet, different experimental studies showed that, in transgenic rats, rich saturated fatty acid diet induced progressive atherosclerotic lesions, resembling those observed by us, but also some aspects described in human pathology. Conclusions: Our experimental study reveals differences in atherogenesis under saturated vs. unsaturated fatty diet.