Blueberries Abstracts 3

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A berry thought-provoking idea: the potential role of plant polyphenols in the treatment of age-related cognitive disorders.
            (Cherniack, 2012) Download
Today, tens of millions of elderly individuals worldwide suffer from dementia. While the pathogenesis of dementia is complex and incompletely understood, it may be, at least to a certain extent, the consequence of systemic vascular pathology. The metabolic syndrome and its individual components induce a proinflammatory state that damages blood vessels. This condition of chronic inflammation may damage the vasculature of the brain or be directly neurotoxic. Associations have been established between the metabolic syndrome, its constituents and dementia. A relationship has also been observed between certain dietary factors, such as constituents of the 'Mediterranean diet', and the metabolic syndrome; similar associations have been noted between these dietary factors and dementia. Fruit juices and extracts are under investigation as treatments for cognitive impairment. Blueberry, strawberry, blackberry, grape and plum juices or extracts have been successfully tested in cognitively impaired rodents. Published trials of the benefits of grape and blueberry juice in the treatment of small numbers of cognitively impaired persons have recently appeared. The benefits of fruit products are thought to be a result of its polyphenol content. A grape polyphenol found in grapes, resveratrol, now being studied in humans, and one in grapes and blueberries, pterostilbene, have been found to improve cognition in rodents. In the design of future human trials, one ought to consider the poor bioavailability of these products, the possible need to initiate the experimental therapy long before the onset of symptoms, and currently limited knowledge about the appropriate form (e.g. juice, powder or individual polyphenol) of treatment.

Pterostilbene: Biomedical applications.
            (Estrela et al., 2013) Download
Resveratrol and its naturally dimethylated analog, pterostilbene, show similar biological activities. However, the higher in vivo bioavailability of pterostilbene represents a fundamental advantage. The main focus of this review is on biomedical applications of pterostilbene. The metabolism and pharmacokinetics of this stilbene in inflammatory dermatoses and photoprotection, cancer prevention and therapy, insulin sensitivity, blood glycemia and lipid levels, cardiovascular diseases, aging, and memory and cognition are addressed. Safety and toxicity, as well as recommendations for future research and biomedical uses, are discussed. This review includes comparisons between pterostilbene and other polyphenols, with particular emphasis on resveratrol. Potential benefits of using combinations of different polyphenols are considered. Based on present evidences we conclude that pterostilbene is an active phytonutrient and also a potential drug with multiple biomedical applications.

mTOR signaling at a glance.
            (Laplante and Sabatini, 2009) Download
The mammalian target of rapamycin (mTOR) signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of cell metabolism, growth, proliferation and survival.

Short-term blueberry-enriched diet prevents and reverses object recognition memory loss in aging rats.
            (Malin et al., 2011) Download
OBJECTIVE:  Previously, 4 mo of a blueberry-enriched (BB) antioxidant diet prevented impaired object recognition memory in aging rats. Experiment 1 determined whether 1- and 2-mo BB diets would have a similar effect and whether the benefits would disappear promptly after terminating the diets. Experiment 2 determined whether a 1-mo BB diet could subsequently reverse existing object memory impairment in aging rats. METHODS:  In experiment 1, Fischer-344 rats were maintained on an appropriate control diet or on 1 or 2 mo of the BB diet before testing object memory at 19 mo postnatally. In experiment 2, rats were tested for object recognition memory at 19 mo and again at 20 mo after 1 mo of maintenance on a 2% BB or control diet. RESULTS:  In experiment 1, the control group performed no better than chance, whereas the 1- and 2-mo BB diet groups performed similarly and significantly better than controls. The 2-mo BB-diet group, but not the 1-mo group, maintained its performance over a subsequent month on a standard laboratory diet. In experiment 2, the 19-mo-old rats performed near chance. At 20 mo of age, the rats subsequently maintained on the BB diet significantly increased their object memory scores, whereas the control diet group exhibited a non-significant decline. The change in object memory scores differed significantly between the two diet groups. CONCLUSION:  These results suggest that a considerable degree of age-related object memory decline can be prevented and reversed by brief maintenance on BB diets.


 

Mitochondrial dysfunction is a trigger of Alzheimer's disease pathophysiology.
            (Moreira et al., 2010) Download
Mitochondria are uniquely poised to play a pivotal role in neuronal cell survival or death because they are regulators of both energy metabolism and cell death pathways. Extensive literature exists supporting a role for mitochondrial dysfunction and oxidative damage in the pathogenesis of Alzheimer's disease. This review discusses evidence indicating that mitochondrial dysfunction has an early and preponderant role in Alzheimer's disease. Furthermore, the link between mitochondrial dysfunction and autophagy in Alzheimer's disease is also discussed. As a result of insufficient digestion of oxidatively damaged macromolecules and organelles by autophagy, neurons progressively accumulate lipofuscin that could exacerbate neuronal dysfunction. Since autophagy is the major pathway involved in the degradation of protein aggregates and defective organelles, an intense interest in developing autophagy-related therapies is growing among the scientific community. The final part of this review is devoted to discuss autophagy as a potential target of therapeutic interventions in Alzheimer's disease pathophysiology.

Blueberries and neuronal aging.
            (Shukitt-Hale, 2012) Download
As the population of people in the United States over the age of 65 years continues to increase, so too will the incidence of age-related pathologies, including decreases in cognitive and motor function. In cases of severe deficits in memory or motor function, hospitalization and/or custodial care would be a likely outcome. This means that unless some way is found to reduce these age-related decrements in neuronal function, health care costs will continue to rise exponentially. Evidence is accumulating that consumption of blueberries may be one strategy to forestall or even reverse age-related neuronal deficits, as well as their subsequent behavioral manifestations, in order to increase healthy aging. Research suggests that the polyphenolic compounds found in blueberries exert their beneficial effects either through their ability to lower oxidative stress and inflammation or directly by altering the signaling involved in neuronal communication. These interventions, in turn, may protect against age-related deficits in cognitive and motor function. Appropriately, the US Department of Agriculture has figured prominently in these discoveries, through the efforts of two USDA researchers who worked for the department 100 years apart.


 

The beneficial effects of berries on cognition, motor behaviour and neuronal function in ageing.
            (Shukitt-Hale et al., 2015) Download
Previously, it has been shown that strawberry (SB) or blueberry (BB) supplementations, when fed to rats from 19 to 21 months of age, reverse age-related decrements in motor and cognitive performance. We have postulated that these effects may be the result of a number of positive benefits of the berry polyphenols, including decreased stress signalling, increased neurogenesis, and increased signals involved in learning and memory. Thus, the present study was carried out to examine these mechanisms in aged animals by administering a control, 2 % SB- or 2 % BB-supplemented diet to aged Fischer 344 rats for 8 weeks to ascertain their effectiveness in reversing age-related deficits in behavioural and neuronal function. The results showed that rats consuming the berry diets exhibited enhanced motor performance and improved cognition, specifically working memory. In addition, the rats supplemented with BB and SB diets showed increased hippocampal neurogenesis and expression of insulin-like growth factor 1, although the improvements in working memory performance could not solely be explained by these increases. The diverse polyphenolics in these berry fruits may have additional mechanisms of action that could account for their relative differences in efficacy.

Pterostilbene, a natural small-molecular compound, promotes cytoprotective macroautophagy in vascular endothelial cells.
            (Zhang et al., 2013) Download
Chemical modulators of macroautophagy (herein referred to as autophagy) have aroused widespread interest among biologists and clinical physicians because of their potential for disease therapy. Pterostilbene (PT), a natural small-molecular compound, has been demonstrated to inhibit oxidized low-density lipoprotein (oxLDL)-induced apoptosis in vascular endothelial cells (VECs). The aim of the present study was to investigate whether and how PT could induce VEC autophagy. PT at 0.5 or 1 μM could effectively induce autophagosome formation in human umbilical vein VECs (HUVECs). PT promoted autophagy via a rapid elevation in intracellular calcium ([Ca(2+)]i) concentration and subsequent AMP-activated protein kinase α1 subunit (AMPKα1) activation, which in turn inhibited mammalian target of rapamycin, a potent inhibitor of autophagy. PT-induced AMPKα1 activation and autophagy were refractory to the depletion of serine/threonine kinase 11 but depended on calcium/calmodulin-dependent protein kinase kinase-β activation. Interestingly, PT stimulated cytoprotective autophagy so as to aid in the removal of accumulated toxic oxLDL and inhibit apoptosis in HUVECs. Our study provides a potent small molecule enhancer of autophagy and a novel useful tool in exploring the molecular mechanisms for crosstalk between apoptosis and autophagy. PT could serve as a potential lead compound for developing a class of autophagy regulator as autophagy-related diseases therapy.

 

References

Cherniack, EP (2012), ‘A berry thought-provoking idea: the potential role of plant polyphenols in the treatment of age-related cognitive disorders.’, Br J Nutr, 108 (5), 794-800. PubMed: 22475317
Estrela, JM, et al. (2013), ‘Pterostilbene: Biomedical applications.’, Crit Rev Clin Lab Sci, 50 (3), 65-78. PubMed: 23808710
Laplante, M and DM Sabatini (2009), ‘mTOR signaling at a glance.’, J Cell Sci, 122 (Pt 20), 3589-94. PubMed: 19812304
Malin, DH, et al. (2011), ‘Short-term blueberry-enriched diet prevents and reverses object recognition memory loss in aging rats.’, Nutrition, 27 (3), 338-42. PubMed: 21168307
Moreira, PI, et al. (2010), ‘Mitochondrial dysfunction is a trigger of Alzheimer’s disease pathophysiology.’, Biochim Biophys Acta, 1802 (1), 2-10. PubMed: 19853658
Shukitt-Hale, B (2012), ‘Blueberries and neuronal aging.’, Gerontology, 58 (6), 518-23. PubMed: 22907211
Shukitt-Hale, B, et al. (2015), ‘The beneficial effects of berries on cognition, motor behaviour and neuronal function in ageing.’, Br J Nutr, 114 (10), 1542-49. PubMed: 26392037
Zhang, L, et al. (2013), ‘Pterostilbene, a natural small-molecular compound, promotes cytoprotective macroautophagy in vascular endothelial cells.’, J Nutr Biochem, 24 (5), 903-11. PubMed: 22898568