In previous studies we had shown that intermittent fasting (IF) is neuroprotective in rodent models of Alzheimer's and Parkinson's 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 Huntington's disease. In a more recent study we have shown that dietary restriction is beneficial in a monkey model of Parkinson's 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. In other studies we have shown that IF can improve glucose metabolism (increased insulin sensitivity) and cardiovascular risk factors (decreased blood pressure and superior cardiovascular stress adaptation) in rats. The latter effects of IF were mimicked by intermittent feeding of rats a diet supplemented with 2-deoxyglucoe, a non-metabolizable analog of glucose. Interestingly, IF and caloric restriction also increase heart rate variability in a manner suggesting that these diets increase parasympathetic tone, while decreasing sympathetic tone. Thus, IF and caloric restriction exert physiological actions that would be expected to reduce the risk of diabetes and cardiovascular disease. In our efforts to establish the mechanism by which dietary restriction protects neurons we have found that dietary restriction increases the expression of mitochondrial uncoupling proteins and enzymes of the plasma membrane redox system, resulting in a decrease in oxidative stress and stabilization of cellular energy homeostasis in neurons.
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