Chronic cerebrovascular ischemia in aged rats: effects on brain metabolic capacity and behavior

The objective of this study was to model one of the risk factors for the development of late-onset Alzheimer's disease, decreased cerebral blood flow. Aging rats were tested for visuospatial behavioral deficits after permanent surgical occlusion of both carotid arteries. This was followed after 4 weeks by quantitative cytochrome oxidase histochemical mapping of metabolic capacity throughout the brain. The brain regions affected were related to observed deficits in spatial memory (CA1 and posterior parietal cortex), visually guided movements (superior colliculus and secondary visual cortex), motor coordination (red nucleus), and escape behavior (central gray). The results suggest that deficits in visuospatial learning are not exclusively the result of hippocampal dysfunction, but may be directly correlated with altered oxidative energy metabolism in other integrative visuomotor regions identified in this study. It was concluded that chronic cerebrovascular ischemia in this aged rat model produces neurometabolic and behavioral alterations that may be relevant for an increased risk for the development of Alzheimer's disease.