The effect of n-3 polyunsaturated fatty acid-rich diets on cognitive and cerebrovascular parameters in chronic cerebral hypoperfusion

Western diets consist to a large part of n-6 polyunsaturated fatty acids (PUFAs). These n-6 PUFAs and their conversion products favor immune and inflammatory reactions and compromise vasoregulation, which can contribute to the development of dementia. Recent epidemiological studies associated dementia, particularly the type accompanied by a vascular component, with high, saturated dietary fat intake. Conversely, high fish consumption (a source of long chain n-3 PUFAs) was related to a reduced risk for cognitive decline. Therefore we studied the effects of long chain n-3 PUFAs in rats with bilateral occlusion of the common carotid arteries (2VO), which mimics cerebral hypoperfusion, a risk factor for dementia. Male Wistar rats received experimental diets with a decreased (n-6)/(n-3) ratio from weaning on. At the age of 3 months, the animals underwent 2VO surgery. The rats were tested in the elevated plus maze, an active avoidance paradigm and the Morris water maze (at different survival times). Following behavioral testing, the animals were sacrificed at the age of 7 months. The frontoparietal cortex was analyzed for capillary ultrastructure with electron microscopy. No effects of cerebral hypoperfusion or diet were found on elevated plus maze and active avoidance, while spatial memory in the Morris maze was compromised due to cerebral hypoperfusion under placebo dietary conditions. n-3 PUFA supplementation in combination with extra additives improved the performance of the 2VO animals. The number of endothelial mitochondria, as well as the ratio of microvessels with degenerative pericytes appeared to be lower due to long chain n-3 PUFAs. These results may indicate an improved condition of the blood–brain barrier.