Effect of polyphenol rich blueberry extract on cognitive performance of mice; concominant changes of brain antioxidant markers and acetylcholinesterase
The purpose of this study was to examine, in vivo, the effect on congnitive performance in adult, male Balb-c mice (3–4 months old, n=9/group) of intraperitoneal injections (30 and 60mg/kg, daily for 7 days) of a polyphenol-rich extract of Vaccinium angustifolium wild fruits (blueberries). Mice in the control group received i.p. injections of saline. Evaluation of rodent learning and memory was done by step-through test on day 6 after an initial acquisition trial on day 5. Mice were sacrificed on day 7 and the effects on antioxidant status and acetylcholinesterase of whole brain homogenates was studied by determination of ferric reducing antioxidant power (FRAP), ascorbic acid concentration (colorimetric), malondialdehyde levels (fluorometric) and of acetylcholinesterase activity by the Ellman's reagent. Results showed that the blueberry (60mg/kg)-treated mice exhibited a significant improvement in learning and memory (step-through latency time of 228±107s compared to 101±92s of the control group). Blueberry extract administration also resulted in reduced lipid peroxidation products in brain and in higher brain ascorbic acid levels of both groups. Furthermore, both salt-soluble and detergent-soluble acetylcholinesterase activity was significantly decreased in both treated groups. Thus, for the first time, we show that the significant cognitive enhancement of short-term supplementation with blueberry polyphenols of adult mice is closely related with the higher brain antioxidant properties and the inhibition of the acetylcholinesterase they confer. These findings stress the great impact of nutrition on brain function.