Prolonged docosahexaenoic acid suplementation improves stress-evoked cognitive impairment in rats
Omega-3 polyunsaturated fatty acids (FAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may slow cognitive decline. DHA plays an important role in neural function. Decreases in plasma DHA are associated with cognitive decline in healthy elderly adults and in patients with Alzheimer’s disease. In this study we tested a hypothesis that DHA - active constituent of cod liver oil alleviates negative impact of prolonged restraint stress on cognititive functions of male Wistar rats. Specifically, we attempted to characterize the preventive action of long-lasting treatment with DHA (daily dose 300 mg/kg, p.o. for 21 days) in comparison with positive control (fluoxetine: 10 mg/ kg daily, p.o. for 21 days) against an impairment caused by chronic restraint stress (2 h daily for 21 days) on recognition memory tested in an object recognition task and on the spatial working memory tested in Morris water maze (MWM). We found that DHA administration statistically significantly prevented deleterious effects of chronic restraint stress both on recognition (p<0.01) and the working spatial memory (p<0.001). In conclusion, the present study demonstrated that prolonged treatment with a standardized high-concentration DHA preparation reduced stress-induced spatial reference and working memory and recognition memory impairments as measured in the MWM and object recognition task. The present findings not only corroborate the sparse literature concerning the behavioral effects of DHA but also demonstrate for the first time that the use of DHA facilitates functional recovery after stress evoked cognitive brain damage with potency comparable with fluoxetine. This effect appears to be sustained over time.
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