AGING, MODULATION OF FOOD-INTAKE AND SPATIAL MEMORY - A LONGITUDINAL-STUDY

This longitudinal study investigates the effects of different long-term dietary treatments on spatial memory in rats. An ad libitum group, a group of rats fasting two days a week, and a group fed 70 % of the ad libitum food intake were studied at 6, 12, 19 and 24 months of age. Spatial memory was tested in the Morris water maze. Three test situations were presented: a spatial learning test, a retrieval test, and a reversal test. In the first test, the animals had to find a submerged platform which remained in a fixed location throughout the study. Dietary treatment of rats had no effect on the performances at any of the ages tested. In the retrieval test, rats had to search for the location of the trained platform which had been removed for two minutes. All three groups searched at the correct location at 12 months of age. However, at 19 and 24 months of age, the ad libitum and fasting groups showed a significant deterioration in performance. This was not the case for the 70 % restricted rats. In the reversal test, the platform which had been at the same location for the spatial learning test was moved into the opposite quadrant. The 70 % restricted 24 month old rats adapted to the new situation by rapidly changing their swimming pattern. Again this was not the case for the two other groups. In conclusion, our study shows that food restriction is beneficial to old rats tested throughout their life in the Morris water maze, especially in the retrieval and reversal tests. Our study also indicates that food restriction and fasting do not have the same effect on the spatial memory in the old rats although this needs to be substantiated with further inquiries.