Docosahexaenoic Acid Reduces Amyloid-β

The effect of supplementation with the omega 3 polyunsaturated fatty acid (n-3 PUFA) docosahexaenoic acid (DHA) on membrane composition and amyloid-β1−42 (Aβ42) secretion was studied in human amyloid-β protein precursor-transfected Chinese Hamster Ovary (CHO) cells. Twenty-four hour incubation with a range of DHA concentrations resulted in a dosedependent increase in membrane DHA and eicosapentaenoic acid content and a decrease in arachidonic acid content. In addition, DHA supplementation caused a dose-dependent reduction in the secreted Aβ42 levels and resulted in a 4–8 fold decrease in extracellular prostaglandin E2 (PGE2) levels. Tocopherol, which was added to DHA to prevent oxidation, may have contributed to the effect of DHA, since it slightly decreased extracellular Aβ42 and PGE2 levels when given alone. The addition of selective COX-2 inhibitors Celebrex and curcumin to the culture medium resulted in a significant and comparable inhibition of PGE2 release, but did not inhibit Aβ42 secretion, and even significantly increased Aβ42 production in this cell system. Together, the present data show that, whereas both DHA and COX-2 inhibitors may reduce PGE2 production, only DHA in the presence of tocopherol significantly reduced Aβ42 production and concurrently changed membrane lipid composition in CHO cells. It is concluded that in this in vitro setting DHA reduced Aβ42 secretion through membrane-related, but not PGE2-related mechanisms.