Enriched endogenous n-3 polyunsaturated fatty acids alleviate cognitive and behavioral deficits in a mice model of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that accompanied by memory deficits and neuropsychiatric dysfunction. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have seemly therapeutic potential in AD, but the benefit of n-3 PUFAs is still in debates. Here, we employed a transgenic mice carry fat-1 gene to encode n-3 desaturase from Caenorhabditis elegans, which increase endogenous n-3 PUFAs by converting n-6 PUFAs to n-3 PUFAs crossed with amyloid precursor protein (APP) Tg mice to evaluate the protective effects of endogenous n-3 PUFAs on cognitive and behavioral deficits of APP Tg mice. We fed APP, APP/fat-1 and fat-1 mice with n-6 PUFAs rich diet. Brain tissues were collected at 3, 9 and 12 months for fatty acid and gene expression analysis, histology and protein assays. Morris Water Maze Test, open field test and elevated plus maze test were performed to measure the behavior capability. From the results, the expression of fat-1 transgene increased cortical n-3: n-6 PUFAs ratio and n-3 PUFAs concentrations, and sensorimotor dysfunction and cognitive deficits in AD were significantly less severe in APP/fat-1 mice with endogenous n-3 PUFAs than in APP mice controls. The protection against disturbance of spontaneous motor activity and cognitive deficits in AD was strongly correlated with increased n-3: n-6 PUFAs ratio and endogenous n-3 PUFAs, reduced APP generation, inhibited amyloid β peptide aggregation, suppressed nuclear factor-kappa B and astroglia activation, and reduced death of neurons in the cortex of APP/fat-1 mice compared with APP mice controls. In conclusion, our study demonstrates that an available medication with the maintenance of enriched n-3 PUFAs in the brain could slow down cognitive decline and prevent neuropsychological disorder in AD.