Abstract: Purpose: To investigate whether docosahexaenoic acid (DHA) can prolong the life span of Drosophila melanogaster with Alzheimer’s disease (AD) by increasing the antioxidant capacity. Methods: Wild-type male D. melanogaster were assigned to a normal control group, and AD male D. melanogaster were randomly divided into four groups: model, 0.025, 0.05 and 0.1 mmol/L DHA intervention. The locomotor activity of D. melanogaster in each group was detected by tube climbing test. The expression levels of SOD and CAT in D. melanogaster were detected by real-time polymerase chain reaction (PCR), and the antioxidant capacity was measured. The expression levels of the Sirt2, Rpn11 and MTH genes were detected by real-time PCR, and the average survival time and survival curve of D. melanogaster in each group were calculated. Results: Compared with the control group, the crawling index of AD D. melanogaster decreased (P < 0.01). Compared with the model group, 0.05 mmol/L DHA treatment significantly increased the tube-climbing capacity of D. melanogaster (P < 0.05). The results of real-time PCR showed that compared with the model group, the expression levels of the SOD and CAT genes were up-regulated in the 0.05 mmol/L DHA treatment group (P < 0.05), and the total antioxidant capacity and superoxide dismutase activity significantly increased compared with the model group (P < 0.05). In addition, DHA treatment significantly up-regulated the expression levels of the lifespan-associated genes Sirt2, Rpn11 and MTH (P < 0.05). The results of survival test showed that the survival probability of AD D. melanogaster significantly dropped. Compared with the model group, the average survival time of D. melanogaster treated with 0.05 mmol/L DHA was significantly up-regulated (P < 0.05), and the survival probability was higher than that of AD D. melanogaster. Conclusion: DHA improved the crawling capacity of AD D. melanogaster and the expression of the antioxidant genes SOD and CAT, and increased the antioxidant capacity. Additionally, DHA upregulated the expression levels of the Sirt2, Rpn11 and MTH genes, thereby prolonging the lifespan of D. melanogaster.

Key words: docosahexaenoic acid; Alzheimer’s disease; lifespan; antioxidant; Drosophila melanogaster