Protective effects of prescription n-3 fatty acids against impairment of spatial cognitive learning ability in amyloid β-infused rats

Abstract

Deposition of amyloid β peptide (Aβ) into the brain causes cognitive impairment. We investigated whether prescription pre-administration of n-3 fatty acids improves cognitive learning ability in young rats and whether it protects against learning ability impairments in an animal model of Alzheimer's disease that was prepared by infusion of Aβ_1–40 into the cerebral ventricles of rats. Pre-administration of TAK-085 (highly purified and concentrated n-3 fatty acids containing eicosapentaenoic acid ethyl ester and docosahexaenoic acid ethyl ester) at 300 mg kg⁻¹ day⁻¹ for 12 weeks significantly reduced the number of reference memory errors in an 8-arm radial maze, suggesting that long-term administration of TAK-085 improves cognitive leaning ability in rats. After pre-administration, the control group was divided into the vehicle and Aβ-infused groups, whereas the TAK-085 pre-administration group was divided into the TAK-085 and TAK-085 + Aβ groups (TAK-085-pre-administered Aβ-infused rats). Aβ_1–40 or vehicle was infused into the cerebral ventricle using a mini osmotic pump. Pre-administration of TAK-085 to the Aβ-infused rats significantly suppressed the number of reference and working memory errors and decreased the levels of lipid peroxide and reactive oxygen species in the cerebral cortex and hippocampus of Aβ-infused rats, suggesting that TAK-085 increases antioxidative defenses. The present study suggests that long-term administration of TAK-085 is a possible therapeutic agent for protecting against Alzheimer's disease-induced learning deficiencies.