Submitted to: Nutritional Neuroscience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/1/2005
Publication Date: 4/1/2005
Citation: Andres-Lacueva, C., Shukitt Hale, B., Galli, R.L., Jaurengui, O., Lamuela-Raventos, R.M., Joseph, J.A. 2005. Anthocyanins in aged blueberry-fed rats are found centrally and may enhance memory. Nutritional Neuroscience, April 2005:8(2): 111-120. Interpretive Summary: The compounds in fruits and vegetables that may be responsible for the postulated health benefits that may occur from eating a diet high in their content are called polyphenolics (flavonoids). They are known to be very potent antioxidants. Our laboratory found that various fruit and vegetable extracts, particularly blueberry (BB), were effective in reversing age-related deficits in brain function, i.e., memory and motor performance in old rats following 8 weeks supplementation BB. We believe that these changes may be due to the polyphenolic content of the BB. However, because of a barrier known as the blood brain barrier that might prevent their passage into the brain we were not sure that the beneficial effects of polyphenolics were being delivered centrally (in the brain). One class of polyphenolics that may be especially important in providing the benefits on behavior and neuronal function are called anthocyanins. They provide the blue color to blueberries. Therefore, we examined whether BB anthocyanins could access the brain and whether there was a relationship between the number of anthocyanins found in various brain regions and memory performance. The results indicated several anthocyanins could be localized in the brain and the correlation between the number of anthocyanins found in the cortex and the number of errors made on a maze was significant (r =-0.78, p < 0.03). That is, the greater the number of anthocyanins found in the cortex the fewer errors the animals made on the maze. This is the first time that anthocyanins from a dietary source have been found to localize in the brain and influence behavior. These findings suggest that these compounds may deliver their health benefits centrally as well as peripherally.
Technical Abstract: Research has shown that fruits and vegetables containing high levels of polyphenolics (flavonoids) display high total antioxidant activity. Our laboratory found that various fruit and vegetable extracts, particularly blueberry (BB), were effective in reversing age-related deficits in neuronal signaling and behavioral parameters following 8 weeks of feeding, possibly due to their polyphenolic content. However, it was unclear if these phytonutrients were able to directly access the brain from dietary BB supplementation (BBS). The present study examined whether different classes of polyphenols could be found in brain areas associated with cognitive performance following BBS. Thus, 19 month old F344 rats were fed a control or 2% BB diet for 8-10 weeks and tested in the Morris water maze (MWM), a measure of spatial learning and memory. LC-MS analyses of anthocyanins in the diet and subsequently in different brain regions of BBS and control rats were carried out. Several anthocyanins (cyanidin-3-O-B-galactoside, cyanidin-3-O-B-glucoside, cyanidin-3-O-B-arabinose, malvidin-3-O-B-galactoside, malvidin-3-O-B-glucoside, malvidin-3-O-B-arabinose, peonidin-3-O-B-arabinose and delphinidin -3-O-B-galactoside) were found in the cerebellum, cortex, hippocampus, or striatum of the BBS rats, but not the controls. These findings are the first to suggest that polyphenolic compounds are able to cross the blood brain barrier and localize in various brain regions important for learning and memory. Correlational analyses revealed a relationship between MWM performance in BBS rats and the total number of anthocyanin compounds found in the cortex. These findings suggest that these compounds may deliver their antioxidant and signaling modifying capabilities centrally.