In previous studies we had shown that intermittent fasting (IF) is neuroprotective in rodent models of Alzheimers and Parkinsons diseases and stroke. The neuroprotective mechanism involves induction of a mild beneficial cellular response as indicated by increased expression of heat-shock proteins and brain-derived neurotrophic factor (BDNF). We have found that IF increases BDNF levels in the brain, ameliorates diabetes, suppresses neuronal degeneration in the striatum and cortex, and extends survival in a mouse model of Huntingtons disease. In a more recent study we have shown that dietary restriction is beneficial in a monkey model of Parkinsons disease. We have recently provided evidence that dietary lipids may modulate risk of AD and ALS. Levels of cholesterol and long-chain ceramides are increased in membranes of cells in the brains of AD patients and spinal cords of ALS patients. Additional data in studies of cell culture and animal models of AD and ALS suggest that ceramides may play an important role in the cell death process in these disorders. Because levels of cholesterol, sphingolipids and ceramides can be modulated by changes in diet, our data suggest that dietary lipids may modify the vulnerability of neurons to age-related diseases. We screened a panel of 'biopesticides' to identify naturally occurring chemicals that can activate adaptive stress response pathways in neurons and so can protect the neurons against dysfunction and degeneration in experimental models of neurodegenerative disorders. This project identified the phytochemical plumbagin as a lead candidate neuroprotective agent that we are currently further evaluating in preclinical studies. Finally, we have found that dietary energy intake affects neural circuits in the brain involved in drug addiction, and that dietary energy intake can counteract several adverse effects of cocaine on neural plasticity and behavioral features of addiction. In a collaborative study of human subjects we compared the feasibility and effectiveness of intermittent continuous energy (IER) with continuous energy restriction (CER) for weight loss, insulin sensitivity and other metabolic disease risk markers. The study was a randomized comparison of a 25% energy restriction as IER (2710 kJ/day for 2 days/week) or CER (6276 kJ/day for 7 days/week) in 107 overweight or obese premenopausal women observed over a period of 6 months. Both groups experienced comparable reductions in leptin, free androgen index, high-sensitivity C-reactive protein, total and LDL cholesterol, triglycerides, blood pressure and increases in sex hormone binding globulin, IGF binding proteins 1 and 2. Reductions in fasting insulin and insulin resistance were modest in both groups, but greater with IER than with CER. Our findings show that IER is as effective as CER with regard to weight loss, insulin sensitivity and other health biomarkers, and may be offered as an alternative equivalent to CER for weight loss and reducing disease risk. Parkinson's disease (PD) patients often exhibit impaired regulation of heart rate by the autonomic nervous system (ANS) that may precede motor symptoms in many cases. Results of autopsy studies suggest that brainstem pathology, including the accumulation of -synuclein, precedes damage to dopaminergic neurons in the substantia nigra in PD. However, the molecular and cellular mechanisms responsible for the early dysfunction of brainstem autonomic neurons are unknown. Here we report that mice expressing a mutant form of synuclein that causes familial PD exhibit aberrant autonomic control of the heart characterized by elevated resting heart rate and an impaired cardiovascular stress response, associated with reduced parasympathetic activity and accumulation of synuclein in the brainstem. These ANS abnormalities occur early in the disease process. Adverse effects of synuclein on the control of heart rate are exacerbated by a high energy diet and ameliorated by intermittent energy restriction. Our findings establish a mouse model of early dysregulation of brainstem control of the cardiovascular system in PD, and further suggest the potential for energy restriction to attenuate ANS dysfunction, particularly in overweight individuals. In another study we found that mortality from focal ischemic stroke was increased with advancing age and reduced by an intermittent fasting (IF) diet. Brain damage and functional impairment were reduced by IF in young and middle-aged mice, but not in old mice. The basal and poststroke levels of neurotrophic factors (brain-derived neurotrophic factor and basic fibroblast growth factor), protein chaperones (heat shock protein 70 and glucose regulated protein 78), and the antioxidant enzyme heme oxygenase-1 were decreased, whereas levels of inflammatory cytokines were increased in the cerebral cortex and striatum of old mice compared with younger mice. IF coordinately increased levels of protective proteins and decreased inflammatory cytokines in young, but not in old mice. We further found that intermittent fasting suppresses activation of the so-called 'inflammasome' in brain cells, which was associated with improved functional outcome in the mouse stroke model. We conclude that dietary energy intake differentially modulates neurotrophic and inflammatory pathways to protect neurons against ischemic injury, and these beneficial effects of IF are compromised during aging, resulting in increased brain damage and poorer functional outcome. The 3xTgAD mouse model was used to test the hypothesis that a ketone ester-based diet can ameliorate AD pathogenesis. Beginning at a presymptomatic age, 2 groups of male 3xTgAD mice were fed a diet containing a physiological enantiomeric precursor of ketone bodies (KET) or an isocaloric carbohydrate diet. The results of behavioral tests performed at 4 and 7 months after diet initiation revealed that KET-fed mice exhibited significantly less anxiety in 2 different tests. 3xTgAD mice on the KET diet also exhibited significant, albeit relatively subtle, improvements in performance on learning and memory tests. Immunohistochemical analyses revealed that KET-fed mice exhibited decreased Abeta; deposition in the subiculum, CA1 and CA3 regions of the hippocampus, and the amygdala. KET-fed mice exhibited reduced levels of hyperphosphorylated tau deposition in the hippocampus and amygdala. These findings demonstrate a therapeutic benefit of a diet containing a ketone ester in a mouse model of Alzheimer's disease. Based on our own research and evolutionary considerations, we developed a novel hypothesis to explain the beneficial effects of diets rich in fruits and vegetables on health, including brain health. Plants do not have the option of fleeing predators. As a consequence, they have developed an elaborate set of chemical defenses to ward off insects and other creatures that want to make them into a meal. Toxins that plants use against predators are consumed by us at low levels in fruits and vegetables. Exposure to these chemicals causes a mild stress reaction that lends resilience to cells in our bodies. Adaptation to these stresses, a process called hormesis, accounts for a number of health benefits, including protection against brain disorders, that we receive from eating vegetables and fruits.
Showing the most recent 10 out of 80 publications
