Effect of fish oil supplementation in a rat model of multiple mild traumatic brain injuries
Wang T., Van KC., Gavitt BJ., Grayson K., Lu Y., Lyeth BG., Pichakron KO. Restorative Neurology and Neuroscience. 2013; ahead of print
Take Home Message: Pre-injury supplementation with omega-3-fatty acids may improve cognitive and physiologic recovery following brain injury.
Repetitive mild traumatic brain injuries (MTBI) may lead to irreversible brain damage due to the secondary effects that follow an MTBI (i.e., oxidativedamage). Omega-3- fatty acids, DHA and EPA, have been show to reduce the secondary effects of an MTBI by reducing oxidative damage. Given the frequency and potential long term effects of repetitive MTBIs it is imperative to find ways to prevent and treat the cumulative effects of an MTBI. Therefore, the purpose of this study was to determine if a diet rich in omega-3 fatty acids would reduce cognitive deficits and neuronal cell death in a fluid-percussion rat model of repetitive MTBI. Twenty-five rats completed the full experiment. Seven rats were excluded due to a bad reaction to the fluid percussion injury or excessive weight loss following the injury. Rat chows were custom made, with the first having an additional 6% fish oil (8-10 g EPA and 8 g DHA; Brevoortia Tyrannus, an Atlantic menhaden fish) and the other having an addition 6% soybean oil (control diet). Both chows had the same calorie count, essential nutrients, and oil content. Rats were randomly assigned to either diet, and were given free access to their respective chow for 4 weeks pre-injury and 2 weeks post injury. After 4 weeks the rats were subjected to a bilateral MTBI via fluid percussion to create a MTBI. After 24 hours a second fluid percussion injury was administered to generate a repeat MTBI. Cognitive evaluation was assessed for 5 consecutive days (days 10-14) via the Morris Water Maze. Following the final cognitive trial the rats were euthanized and the brains were examined for histological differences within the CA2-3 hippocampal regions. The fish oil group was able to find the hidden platform and spent more time within the target quadrant on day 14 post MTBI compared to the soybean oil group. There were no differences observed within days 10-13. There were no differences between the right and left hemispheres in the quantity of surviving CA2-3 neurons; however, there was a trend for the fish oil group to have a greater number of total CA2-3 neurons compared to control diet group.
This is an interesting study that mimicked a repetitive blow to the head that would result in a MTBI. The rats that were given the fish oil chow displayed better terminal cognitive performances within the Morris Water Maze tests by exhibiting greater spatial memory retention than their soybean oil counterparts. The histology demonstrated a trend for those on the fish oil diet to have a greater number of surviving CA2-3 hippocampal neurons. This data suggests that pre-injury supplementation with omega-3-fatty acids may have the potential to improve the cognitive outcome after sustaining multiple MTBIs. This study also suggests that many of the cognitive problems following a concussive event may be due to the secondary effects of the oxidative stress on the tissue, which may be alleviated by fish oil supplementation; however, there was not an injury-free control group for comparison. The fish oil supplementation may offset a variety of the neurometabolic events that occur following a MTBI that helps to preserve or repair cognitive function following injury. Further research is necessary to determine the duration and dose of fish oil to receive benefits. Additionally, it should be distinguished if omega-3-fatty acids from natural food source produce better or similar neuronal protection results compared to supplementation.
Questions for Discussion: Do you think that taking fish oil will help prevent long-term cumulative effects of repetitive brain injury? Have you suggested this for your athletes?
Written by: Jane McDevitt PhD, ATC, CSCS
Reviewed by: Stephen Thomas