Dietary prevention of visual function and cognitive decline by omega-3 polyunsaturated fatty acids in Senescence Accelerated Mouse P8 (SAM P8)

International audiencePurpose: : Neuronal tissues such as the brain and the retina contain elevated amounts of long-chain omega-3 polyunsaturated fatty acids (PUFAs) and particularly docosahexaenoic acid (DHA). DHA concentrations are known to decrease in the aging brain and are associated with cognitive decline. The senescence-accelerated mouse prone 8 (SAM P8) is a mouse model for aging that exhibits deficits in cognitive performances as well as alterations of retinal functionality (ARVO 2004 E-abstract 797). The aim of this study was to evaluate the effects of a dietary supplementation with DHA on mood, cognition and visual functionality of SAM P8 during aging. Methods: : SAM P8 mice were studied in comparison with SAM resistant 1 control animals (SAM R1). Animals were fed from weaning until 12 months of age with either a control diet balanced in omega-3 and omega-6 PUFAs but without DHA, a diet deficient in omega-3 PUFAs or a diet containing 6% of lipids as DHA. After 5 and 12 months of diet, the scotopic ERG was recorded and working memory and despair behavior were evaluated. The fatty acid composition of the retina and the brain was determined using capillary column gas chromatography. Results: : Dietary supplementation with long-chain omega-3 PUFAs led to significantly higher retinal and cerebral levels of DHA. The incorporation rate was significantly higher in SAM P8 when compared to SAM R1. An age-related diminution of the ERG b-wave amplitude was observed from 5 to 12 months of age in control and deficient SAM P8 when compared to SAM R1. These differences were emphasized in deficient animals. No age-related alteration of the ERG b-wave amplitude was observed in SAM P8 Meanwhile dietary supplementation with DHA reduced the duration of immobility in the forced swimming test in SAM R1 but not in SAM P8. Conclusions: : Dietary supplementation with DHA was efficient in increasing its retinal and cerebral incorporation. DHA successfully prevented the age-related loss of visual function in SAM P8 but did not improve the depression-like symptoms