Dietary PUFA supplements reduce memory deficits but not CA1 ischemic injury in rats

The purpose of the present study was to examine the impact of nutritional supplementation with essential omega 3 and 6 fatty acids on CA1 neuronal death and recovery of functional impairments following global ischemia. Groups of Wistar male rats were randomly assigned to four experimental conditions determined by the consumed diet and surgical condition. Rats either received a standard diet (SD; Purina 5012) or a 15% PUFA supplemented diet (FO+CO) prepared by adding 11.5% (w/w) fish oil from menhaden fish and 3.5% corn oil to standard rat chow. Diet conditions were initiated in 30 day old rats and maintained for an 18-week period (pre- and post-surgery). Sham or 8-min global ischemic surgeries occurred during the 13th feeding week and behavioral testing took place following reperfusion for an additional 4 weeks, after which all rats were euthanized. Our findings revealed significant loss of pyramidal CA1 neurons 31 days post ischemia in ischemic as compared to sham-operated rats but no difference between ischemic animals fed the SD or PUFA supplemented diets. In the radial arm maze, SD ischemic rats took longer time to complete the task and made significantly more working memory errors than PUFA ischemic and sham-operated animals. Independent of the diet, ischemic animals appeared less anxious in the elevated plus maze, spending considerably more time in the open arms as compared to sham-operated rats. Taken together, these results suggest that fish oil supplemented diet exerts beneficial effect on ischemia-induced spatial memory deficits despite protective effects on CA1 hippocampal neurons.