Exercise and the brain: something to chew on

Abstract

Evidence is accumulating that exercise has profound benefits for brain function. Physical activity improves learning and memory in humans and animals. Moreover, an active lifestyle might prevent or delay loss of cognitive function with aging or neurodegenerative disease. Recent research indicates that the effects of exercise on the brain can be enhanced by concurrent consumption of natural products such as omega fatty acids or plant polyphenols. The potential synergy between diet and exercise could involve common cellular pathways important for neurogenesis, cell survival, synaptic plasticity and vascular function. Optimal maintenance of brain health might depend on exercise and intake of natural products.

Figure 1

Diet and exercise enhance synaptic plasticity and learning. (a) Exercise and probably diet enhance neurotransmitter and trophic factor levels. These factors directly enhance the function of mature neurons and stimulate the production of new neurons in the hippocampus. (b) Nutrition and exercise affect neuronal signaling pathways important for synaptic plasticity and cognitive function. BDNF and glutamate act at receptors that regulate calcium/calmodulin-dependent protein kinase II (CaMKII) and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) systems. Flavanols might activate similar signaling pathways, raising the possibility that natural compounds have a selective neuronal receptor (? indicates a hypothetical receptor). BDNF also influences the phosphatidylinositol 3-kinase (PI3K)/Akt and the FOXO subfamily of forkhead transcription factors, elevating expression of genes important for learning and memory. Running mouse image photo courtesy of Marc Lieberman.

Figure 2

Exercise and diet have complementary and synergistic effects on brain function. The most profound effect of exercise is on hippocampal neurogenesis, whereas the strongest influence of a flavanol-rich diet might be on vascularization of the brain. (A,B) Bromodeoxyuridine (BrdU) labeling of new cells in the dentate gyrus of the hippocampus of C57Bl/6 mice. In comparison with sedentary controls (A), running wheel exercise (B) enhances the number of new cells. (C,D) Dendritic spines labeled with DiI in mature hippocampal granule cells. Relative to controls (C), running and/or a flavanol-containing diet (D) increase neuronal spine density. (E,F) Tomato lectin staining visualized hippocampal blood vessels; the granule cell layer of the dentate gyrus is outlined in white in the panels. A flavanol-rich diet enhanced dentate gyrus vascularization, especially when combined with running (F), as compared with control mice (E). Abbreviations: CON, control group; EXP, experimental group. Panels A and B were reproduced from Ref. [103]. Panels C, D, E and F: Copyright 2007 by the Society for Neuroscience.