Effect of caloric restriction on memory and tissue damage following traumatic brain injury in the rat

Abstract

While chronic caloric or dietary restriction, characterized by a regular reduction in food intake, improves longevity and reduces the risk of age‐related neurodegenerative disorders and injury following ischemia, its ability to improve outcomes after traumatic brain injury (TBI) has not been explored. Because TBI is a significant problem in aging populations, we hypothesized that caloric restriction would improve learning and memory after TBI. Male Sprague‐Dawley rats were divided into 2 dietary groups, an ad libitum fed group (AL) and a caloric restriction group (CR) that was provided with 70% of the food intake of AL rats (n=10/group). After 4 mos, a weight‐drop device (300g) was used to produce a 2mm medial frontal cortex contusion following craniotomy. Additional animals in each dietary group (n=10) were used as sham‐operated controls. CR resulted in significant learning and memory improvements as measured by Morris Water Maze. After 5 d of training, significantly more CR rats than AL rats were able to find the hidden platform (p<0.05). There was also an approx 80% reduction in the time it took CR rats to find the platform (p<0.05). Additionally, 3 wks post‐injury, there was a significant decrease in the size of the cortical necrotic cavity in CR rats (p<0.05). Work is ongoing to determine the cellular mechanisms at the site of injury and in the hippocampus that are responsible for the role of CR in TBI.