A high fat diet does not exacerbate CA1 injury and cognitive deficits following global ischemia in rats

A diet high in saturated fat and similar in composition to western diets (WD) has been shown to exacerbate injury following traumatic brain injury. Thus, we investigated the effects of a WD on cell death and functional outcome following global ischemia. First we assessed the effects of a 60-day WD regimen on temperature, activity and glucose levels in normal rats (Experiment 1). Second, we evaluated the influence of a 60-day WD regimen on hippocampal CA1 injury and learning and memory impairments following global ischemia in rats (Experiment 2). Male Sprague-Dawley rats, obtained at approximately 50 g, were randomly assigned to either the WD or the low-fat control diet (CD). Animals were fed for 30 days, then subjected to surgery (body temperature probe implantation in experiment 1; forebrain ischemia in experiment 2), and then they stayed on the same diet for another 30 days. Two and 4 weeks following surgery, learning and memory were assessed using the Morris Water Maze. At 60 days, rats were killed and viable hippocampal CA1 cells were quantified. Results from experiment 1 revealed no differences in glucose or temperature profiles between animals fed the WD and CD; however, WD animals were significantly less active than CD animals. Eight minutes of ischemia in experiment 2 induced severe hippocampal CA1 cell loss (approximately 90%) and learning and memory impairments relative to non-ischemic controls. However, the WD did not exacerbate CA1 injury or behavioural deficits. These findings suggest that a 60-day WD regimen does not significantly influence recovery following global ischemia.