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United States Department of Agriculture

Agricultural Research Service

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Location: Boston, Massachusetts

2013 Annual Report

1a. Objectives (from AD-416):
To investigate the epigenetic modulation in the brains of young and old rats by walnuts, which are known for their nutritional benefits on brain health and aging process. Emerging evidences indicate a direct link between age-associated changes in the DNA methylation pattern and onset of neurodegenerative diseases, and these DNA and genomic modulations are directly affected by the diet. In previous studies from our laboratory, walnuts, known for their rich polyunsaturated fatty acids, have shown improved cognitive, behavioral and motor functions in aged rats. We have also reported that part of these benefits are derived from effects at the molecular level, in critical regions of the brain, including but not limited to the altering effects on the membrane, which could possibly facilitate the movement of certain bioactive components across the membranes. In this context the current study directly measures the effect of walnut bioactive components on genomic DNA methylation and methylation of specific genes.

1b. Approach (from AD-416):
Rats will initially be purchased and maintained on a diet containing 0, 6% and 9% walnut extracts for about 2 months. Rats will then complete a battery of motor tests as well as cognitive testing in the Morris water maze. Following behavioral testing, areas of the rats’ brains, specific to learning, memory, and motor coordination, such as hippocampus and striatum will be dissected out. The DNA isolated from these specific regions will be analyzed for global genomic DNA methylation and gene specific DNA methylation pattern using LC-MS and microarray techniques.

3. Progress Report:
Numerous studies have indicated that walnuts protect the aging brain from inflammation and stress, primarily due to their high omega-3 content and unique nutrients. However, the in-depth mechanisms are still evolving, and this study was begun to investigate whether walnuts have any effects on DNA and protect the brains cells from gene changes occurring as we get older. Therefore, young and old rats were fed with an equivalent of 0, 1, or 1.5 oz of walnuts/day for 3 months. Following behavioral testing, DNA was isolated from key regions of the brain. There were differences in cognition, motor function and DNA patterns between young and old rats, and we are currently examining if walnut feeding had any effects on the end points studied. This study is a significant step forward to establish the effect of whole food (walnut) on particular genes.

4. Accomplishments

Last Modified: 2/23/2016
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