Location: Boston, Massachusetts2010 Annual Report
1a. Objectives (from AD-416)
LAB: Nutrition & Neurocognition 1. Determine the role of nutritional factors, especially B-vitamins and choline, in preventing age-related cognitive impairment using human intervention and population studies. 2. Characterize mechanisms by which nutritionally induced hyperhomocysteinemia affects neuronal function and cognitive performance using transgenic and other animal models of human cognitive decline. LAB: Neuroscience 1. Use cell models to develop mechanistic interpretations of the positive benefits of berry polyphenols and fatty acids by examining their direct effects on deficits in stress and protective signaling. 2. Establish the effects of dietary berry fruit extracts and/or fatty acids on behavioral and neuronal deficits in aging to assess the mechanisms involved and the most effective polyphenols/fatty acids in animal and human models.
1b. Approach (from AD-416)
LAB: Nutrition & Neurocognition With the population aging, the imperativeness to understand and prevent age-related cognitive decline and disability grows more important. We approach this problem with nutritional studies in human populations and in studies of animal models. Observational and cohort studies in humans examine the association of modifiable nutritional factors especially B vitamins, vitamin D, and polyunsaturated fatty acids with the trajectory of cognitive decline and measurable brain volumes with age. Intervention studies with B vitamins to lower homocysteine levels in blood and protect against neurological and vascular degeneration examine our ability to delay cognitive decline, dementia, and disability. Genotyping focusing on methylation pathways provide insight into how genetic variability may modify or modulate the neurological response to nutrition and dietary factors. Animal models of aging and dementia are employed to examine the mechanism of nutritional modification of neural and cerebrovascular degeneration with effects on behavior. Rodents are made deficient in B vitamins or polyunsaturated fatty acids or choline and effects on brain function (behavior), brain biochemistry, and brain histology provide insights into pathways by which nutritional perturbations influence aging brain chemistry and function. LAB: Neuroscience The focus of the current project is to elucidate the mechanisms involved in the beneficial effects of berry fruit and polyunsaturated fatty acids (PUFAs) from fish or nut oils on reducing neurodegeneration mediated by oxidative stress (OS) and inflammation (INF). Mixed neuron/ glial cultures obtained from rats of different ages will be employed to delineate the neuroprotective effects of berry fruit or PUFA against OS/INF and subsequent stress mediated by glial cells. Additionally, muscarinic receptor-transfected COS-7 cells will be used to assess OS/INF localization and the effects of membrane lipids on the cellular responses to OS/INF. Extensive motor and cognitive assessments will also be made of senescent animals fed diets containing berry fruit or PUFAs. Finally, we will translate the behavioral findings obtained in our animal studies to the human condition by examining the effects of berry fruit or walnut supplementation on human gait and motor ability. This project will contribute to fundamental new knowledge of the putative role of berry fruit and PUFAs on reducing OS/INF and behavioral deficits in aging. These studies will span basic cellular signaling, animal behavior and cognition, and human motor abilities, allowing for a comprehensive examination of the beneficial effects of berry fruit and nutritional PUFAs on the aging brain.
3. Progress Report
LAB: Nutrition & Neurocognition This project includes the work of a subordinate project at the HNRCA funded through a Specific Cooperative Agreement with Tufts University. For the progress report, see 1950-51000-070-12S. LAB: Neuroscience We have shown that supplementation with fruits and vegetables can forestall and reverse the deleterious effects of aging on neuronal functioning and behavior. While fruits and vegetables may have direct effects on oxidative stress (OS) and inflammation in aging, polyphenolic compounds may also enhance protective signaling and neuronal growth. Discovery of these additional mechanisms might lead to important dietary information to an aging population. Additionally, determining which components might be responsible for the beneficial effects is also important, although it might be that the combination of polyphenols or fatty acids present in berries or nuts may have synergistic effects which provide increased protection from age-related declines relative to individual constituent compounds. This year we continued to study the mechanisms responsible for the beneficial effects of berry fruit. In one study we showed that three berry extracts (blueberry, strawberry and acai berry) were able to rescue neurons through induction of autophagy, a process by which toxic debris is recycled and cleared in neurons. We also began to determine the effects of the berry fruit on stress signaling from different types of brain cells such as microglia, astrocytes, and neurons derived from the mixed cultures. We showed that blueberries (BB) and strawberries (SB) could protect neurons through auxiliary effects on astrocytes when they were co-cultured with the neurons, as they are in the brain. Additionally, we began to examine individual components from berry fruit, acai berry to determine which polyphenolic families might be responsible for their beneficial effects. In addition, in an animal study, we compared the effects of specific compounds found in BBs with the effect of the whole berry on the mobility and behavior of aged rats in doses equivalent to 2 cups/day in humans. The findings suggested that proanthocyanidins may be the polyphenolic family responsible for the protective effects of blueberries, although the whole berry was also effective. Finally, we began to explore age-related alterations in balance, gait, and cognition in humans in a pilot study to validate the gait apparatus and several cognitive tests. Preliminary results show that the methods are sufficiently robust to detect age-related declines in balance, gait, and cognition. This information will allow us to plan a subsequent study to investigate the ability of blueberry or strawberry supplementation to attenuate these age-related performance declines.
1. Blueberries and strawberries protect neurons via a subtype of brain cell. (LAB: NEUROSCIENCE). ARS researchers in Boston, MA found that pretreatment of hippocampal cells (a type of neuronal brain cell) with blueberry and strawberry extract reduced chemically-induced oxidative stress and inflammation. An interesting observation is that when a subtype of brain cell called astrocytes was mixed in the hippocampal cell cultures, the beneficial effects of the blueberry and strawberry were enhanced. Typically it is thought that astrocytes may activate proinflammatory and stress signals that can harm neurons. However blueberry, strawberry, and a combination of the two extracts reduced the inflammatory and stress protein levels in astrocytes, thereby exerting the protective effect. This study used cell cultures that may mimic the interactions of multiple cell types in the human brain and provided additional evidence of the health benefits of blueberry and strawberries on brain health.
2. Acai berry extracts enhance brain health by improving cell function and reducing oxidative stress and inflammation. Exposure of brain cells to inflammation and oxidative stress sets off a cascade of events resulting in death of neurons, ultimately leading to declines in cognitive and motor functions. Age-related loss of cognitive function has been related to the ability of brain cells to regulate calcium balance, but this dysregulation may be prevented by the consumption of berry fruits such as polyphenolic-rich blueberries or strawberries. To demonstrate the mechanism by which berry fruit extracts assist in maintaining regulation of calcium balance, ARS researchers in Boston, MA treated brain cells with different components of acai berry extracts, containing different classes of polyphenolics such as anthocyanins, and subjected the cells to oxidative stress. The acai pulp extracts protected against stress-induced calcium imbalance in hippocampal neuronal cells and a subtype of brain cell called microglia. The results indicate that components of acai berries are effective against oxidative stress-induced calcium imbalance in the brain cells. These berries have been widely popularized as a healthy aging food supplement and this study provides scientific evidence supporting this claim by providing substantial basic information on the mechanisms, chemistry, and efficacy of acai berry in combating age-related cellular dysfunction. These findings help to promote the increase of fruit consumption in the United States.
3. Demonstration of the relationship between brain blood vessel pathology and nutritional folate deficiency. (LAB: Nutrition and Neurocognition). ARS-funded researchers from Tufts University in Boston, MA have shown a diminishing effect of short term nutritional folate (B vitamin) deficiency on cognitive function in animals. These declining cognitive functions in folate-deficient animals were demonstrated to be accompanied by a decrease in the capillary blood supply to the brain by tissue examination. This same deficiency model of cognitive decline allows examination of other factors in Alzheimer's disease including fat and other B vitamins.
4. Folate and choline are two metabolically related essential nutrients which play an important role in cognitive functions in humans and animals. ARS-funded researchers from Tufts University in Boston, MA have shown folic acid (B vitamin) deficiency leads to dysregualtion of the brain choline metabolism and this is demonstrated by altered levels of choline containing substances in brain cell membranes. There is a higher ability to compensate nutritional folate deficiency in young than in adult age, implicating the adult group as a target for study of folate-choline interactions and their role in brain plasticity and cognitive functions.
5. Vitamin K is present in high concentrations in the brain and has been implicated in the regulation of fat metabolism. ARS-funded researchers from Tufts University in Boston, MA have developed an animal model that exploits the difference in the brain’s ability to metabolize two dietary forms of vitamin K. This animal model allowed us to investigate the effect of vitamin K on brain myelin, a well-known contributor to age related cognitive decline. Our findings of a positive relationship between myelin fat and concentration of vitamin K in blood suggest that this animal model may be useful for investigation of the effect of the dietary vitamin K on fat metabolism and behavior functions in humans.
Krikorian, R., Nash, T.A., Shidler, M.D., Shukitt Hale, B., Joseph, J.A. 2009. Concord Grape Juice Supplementation Improves Memory Function In Older Adults with Mild Cognitive Impairment. British Journal of Nutrition. 103:730-734.