Submitted to: Nutritional Neuroscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2004
Publication Date: 4/13/2004
Citation: Goyarzu, P., Malin, D.H., Lau, F.C., Taglialatela, G., Moon, W.D., Jennings, R., Moy, E., Moy, D., Lippold, S., Shukitt Hale, B., Joseph, J.A. 2004. Blueberry supplemented diet: effects on object recognition memory & nuclear factor kappa b levels in aged rats. Nutritional Neuroscience. 7(2):75-83.
Interpretive Summary: In our previous studies we have shown that blueberry (BB) supplementation in aged rats is very effective in reversing both their memory and motor declines and in addition seems to have very potent effects on restoring the ability of neurons to communicate with one another to improve the processing of information in the brain. While we now know that at least some of these improvements in communication involve direct effects on the signaling capabilities of the neurons, it is clear that other mechanisms may be involved. Thus, in an effort to explore additional mechanisms that might be operational in the blueberry-supplemented animals, we tested blueberry-fed and control rats on a test in which their ability to determine whether a new object had been placed in their testing box, one that was different from the one to which they had previously been exposed. Old animals are not able to perform this task, especially if there had been a delay between the time that they first saw the objects and when a new object was put in the test box to replace one of the old objects. However, this deficit was not observed in the old BB-fed animals. Moreover, when several regions of the brain were examined for the levels of a signaling (transcription factor) (nuclear factor kappa B) molecule that is activated under conditions where the animal has increased levels of oxidative stress, such as that seen in aging, this factor was reduced in the BB-fed animals. Since nuclear factor kappa B may act as an antioxidant, these findings indicate that BB may act to reduce overall levels of oxidative stress in aged animals which in-turn facilitates neuronal function and allows for enhancements of memory functions.
Technical Abstract: It has been shown that an antioxidant-rich, blueberry-supplemented (2%) rat diet may retard neurochemical and behavioral aspects of aging. The present study determined whether such supplementation could prevent impaired object recognition memory and elevated levels of the oxidative stress-responsive protein, nuclear factor kappa B NF-kappa B in aged (19-month) Fisher 344 rats. Twelve aged rats had been fed a 2% blueberry supplemented diet for 4 months prior to testing. Eleven aged rats and twelve young (8-month) rats had been fed a control diet. The rats were tested for object recognition memory on the visual paired comparison task. Under conditions of a one-hour delay between training and testing, the aged rats on the control diet performed no better than chance. Both the young rats and the aged blueberry diet rats performed similarly and significantly better than the aged control diet group. Brains from the subjects were dissected into 5 regions: frontal lobe, hippocampus, basal forebrain, striatum and cerebellum. Regional expression of NF-kappa B was determined by western blotting assays. In four regions, aged rats maintained on control diet had significantly higher average NF-kappa B levels than young animals on the control diet. In four regions, aged rats on the blueberry-enriched diet had significantly lower levels of NF-kappa B than aged rats on the control diet. Normalized NF-kappa B levels (averaged across regions and in several individual regions) correlated negatively and significantly with the object memory scores.