Exercise and the brain.

Research output: Chapter in Book/Report/Conference proceedingConference paper

Abstract

Introduction
Physical activity has been associated with the reduction of a number of physical and mental disorders. There is now ample evidence that physical activity decreases the incidence of cardiovascular disease, colon and breast cancer, and obesity, but also diseases such as Alzheimer’s disease (AD), depression, and anxiety.
Neuroinflammation is a defense mechanism aimed at protecting the central nervous system (CNS) against infectious insults and injury. In most cases, it constitutes a beneficial process that ceases once the threat has been eliminated and homeostasis has been restored3. However, long duration neuroinflammatory processes may lead to a progressive neuronal damage observed in many neurodegenerative disorders, most notably Parkinson’s disease (PD) and AD, and also with neuronal injury associated with stroke7.
Nutrition has classically been perceived as a means to provide energy and building materials to the body. However, its ability to prevent and protect against diseases is starting to be recognized. Nutrition and exercise are therefore used as interventions to reverse these possible negative health effects.
Exercise and neurogenesis Animal research has shown that enriched environments, including access to running wheels, has a positive effect on neuronal growth and on the neural systems that are involved in learning and memory. This neuroplasticity refers to the ability of the brain to adapt to environmental change, respond to injury, and to acquire novel information
by modifying neural connectivity and function. Neurotrophins support neuroplasticity,and they are capable of signaling neurons to survive, differentiate, or grow.
Neurotrophic factors not only play a role in neurobiology, but also in central and
peripheral energy metabolism4. Their effect on synaptic plasticity in the CNS involves elements of cellular energy metabolism. Acute exercise and training seem to be key interventions to trigger the processes through which neurotrophins mediate energy metabolism and neural plasticity. Of all neurotrophins, brain-derived neurotrophic factor (BDNF) seems to be the most susceptible to regulation by exercise and physical activity4. BDNF has a wide repertoire of neurotrophic and neuroprotective properties in the CNS and the periphery. These include neuronal protection and survival, neurite expression, axonal and dendritic growth and remodeling, neuronal differentiation, and synaptic plasticity such as synaptogenesis in arborizing axon
terminals, and synaptic transmission efficacy.
In the search of mechanisms underlying plasticity and brain health, exercise is known to induce a cascade of molecular and cellular processes that support (brain) plasticity. BDNF could play a crucial role in these mechanisms.
Nutrition and the Brain
There has recently been growing interest, supported by a number of epidemiological and experimental studies, on the possible beneficial effects of polyphenols on brain health5. Polyphenols are abundant micronutrients in plant-derived foods and are powerful antioxidants. Fruits and beverages such as tea, red wine, cocoa, and coffee are major dietary sources of polyphenols. Polyphenols have been reported to exert their neuroprotective actions through the potential to protect neurons against injury induced by neurotoxins, an ability to suppress neuroinflammation, and the potential
to promote memory, learning, and cognitive function6. Despite significant advances in understanding the biology of polyphenols, they are still mistakenly regarded as simply acting as antioxidants. However, recent evidence suggests that their beneficial effects involve decreases in oxidative/inflammatory stress signaling, increases in protective signaling and neurohormetic effects, leading to the expression of genes that encode antioxidant enzymes, neurotrophic factors, and cytoprotective proteins8. This potential may reside in a number of physiological functions, including their antioxidant properties, their interactions with intracellular signaling pathways, the regulation of cell survival/apoptotic genes and mitochondrial function7.
The largest group of polyphenols is the flavonoids. There are six dietary groups of flavonoids: flavones (e.g. apigenin, luteolin), which are found in parsley and celery; flavanones/flavanonols (e.g. hesperetin, naringenin/astilbin, engeletin), which are mainly found in citrus fruit, herbs (oregano), and wine; isoflavones (e.g. daidzein, genistein), which are mainly found in soy and soy products; flavonols (e.g.kaempferol, quercetin), which are found in onions, leeks, and broccoli; flavanols [e.g.(?)-catechin, (-)-epicatechin, epigallocatechin, and epigallocatechin gallate], which are abundant in green tea, red wine, and chocolate; anthocyanidins (e.g.pelargonidin, cyanidin, andmalvidin), whose sources include red wine and berry fruits. The nonflavonoid group of polyphenols may be separated into two different classes: the phenolic acids, including the hydroxybenzoic acids (C1–C3 skeleton) and hydroxycinnamic acids (C3–C6 skeleton), and the stilbenes (C6–C2–C6 skeleton). Caffeic acid is generally the most abundant phenolic acid, and is mainly found as the quinic ester, chlorogenic acid, in blueberries, kiwis, plums, and apples.
Resveratrol, the main stilbene, can be found in the cis or trans configurations, either glucosylated (piceid) or in lower concentrations as the parent molecule of a family of polymers such as viniferins, pallidol, or ampelopsin A. Resveratrol dietary sources include grapes, wine, and peanuts5.
Polyphenols have been associated with a reduced risk of developing dementia, an improved cognitive performance in normal aging and an improved cognitive
evolution. The neuroprotective actions of dietary polyphenols involve a number of effects within the brain, including a potential to protect neurons against injury induced by neurotoxins, an ability to suppress neuroinflammation, and the potential to promote memory, learning, and cognitive function. While many of the mechanisms underpinning their beneficial effects remain to be elucidated, it has become clear that they partly involve decreases in oxidative/inflammatory stress signaling, increases in protective signaling, and may also involve hormetic effects to protect neurons against oxidative and inflammatory stressors. Emerging evidence suggests that dietaryderived flavonoids have the potential to improve human memory and neurocognitive performance by their ability to protect vulnerable neurons, enhance existing neuronal function, and stimulate neuronal regeneration.
Pollution, exercise and nutrition
Today, air pollution is a growing environmental problem worldwide and the high traffic density in urban environments and cities is a major cause of this prob
morbidity and mortality, particularly in urban settings with elevated oncentrations of
primary pollutants. Air pollution is a very complex mixture of primary and secondary gases and particles, and its potential to cause harm can depend on multiple factors—including physical and chemical characteristics of pollutants, which varies with finescale location (e.g., by proximity to local emission sources)—as well as local meteorology, topography, and population susceptibility. Recently, air pollution exposure has been linked to adverse effects on the brain such as cognitive decline, neuroinflammation and neuropathology2. Inflammation is considered one of the common and basic mechanisms through which air pollution exposure induces negative health effects1. It is envisioned that the latter effects may be aggravated when doing physical activity outdoor in an urban environment. Ventilation rate increases during exercise and in polluted environments, which results in a substantial enhancement of air pollution inhalation2. The question can be raised whether known benefits of regular physical activity on the brain also apply when physical activity is
performed in polluted air. It has been hypothesized that the intake of anti-oxidant and anti-inflammatory nutrients may ameliorate various respiratory and cardiovascular effects of air pollution through reductions in oxidative stress and inflammation. To date, several studies have suggested that some harmful effects of air pollution may be modified by intake of essential micronutrients (such as B vitamins, and vitamins C, D, and E) and long-chain polyunsaturated fatty acids.
The ability of dietary antioxidants to enhance the activity of antioxidant enzymes is vital, as these endogenous enzymes play an integral role in neutralizing the harmful effects of free radicals, such hydrogen peroxide and the superoxide radical. Thus, antioxidant supplementation may be helpful in reducing air pollution-induced oxidative stress in the body, by both direct and indirect mechanisms. Also, cocoa flavanols (epicathechin) may be neuroprotective recent findings suggest that cocoa interventions may be critical for early implementation of neuroprotection of highly exposed urban children. Multi-domain nutraceutical interventions could limit the risk for endothelial dysfunction, cerebral hypoperfusion, neuroinflammation, cognitive
deficits, structural volumetric detrimental brain effects, and the early development of the neuropathological hallmarks of Alzheimer’s and Parkinson’s diseases1.

Conclusion
Exercise is a very powerful mean to interact with the brain. It is clear that exercise has a neuroprotective effect and creates neurogenesis. However, exercising in an polluted environment can have negative effects, while some nutritional interventions such as polyphenols can help to protect the brain against negative effects of pollution.
References
1 - Block ML, Calderon-Garciduenas L. (2009), “Air pollution: mechanisms of
neuroinflammation and CNS disease”, Trends Neurosci, Vol. 32 N° (9), pp. 506–16.
2 - Bos I, De Boever P, Int Panis L, Meeusen R. (2014), “Physical activity, air
pollution and the brain”, Sports Med, Vol. 44 N°11 pp. 1505-18.
3 - Glass, C.K., Saijo, K., Winner, B., Marchetto, M.C., Gage, F.H. (2010),
“Mechanisms underlying inflammation in neurodegeneration”, Cell Vol. 140, pp. 918–
934.
4 - Knaepen K, Goekint M, Heyman EM, Meeusen R. (2010), “Neuroplasticity -
exercise-induced response of peripheral brain-derived neurotrophic factor: a
systematic review of experimental studies in human subjects”, Sports Med, Vol. 40
N° pp. 765-801.
5 - Meeusen R. (2014), “Exercise, nutrition and the Brain”, Sports Med. Vol. 44
Suppl 1 pp. 47-56.
6 - Shukitt-Hale B, Lau FC, Carey AN, et al. (2008), “Blueberry polyphenols attenuate
kainic acid-induced decrements in cognition and alter inflammatory gene expression
in rat hippocampus”, Nutr Neurosci. Vol. 11 N°4 pp. 172–82.
7 - Spencer JP, Vafeiadou K, Williams RJ, Vauzour D. (2012), “Neuroinflammation:
modulation by flavonoids and mechanisms of action”, Mol Aspects Med, Vol. 33 N°1
pp. 83-97.
8 - Vauzour D. (2012), “Dietary polyphenols as modulators of brain functions:
biological actions and molecular mechanisms underpinning their beneficial effects”,
Oxid Med Cell Longev, Vol. 2012 article ID 914273.
Original languageEnglish
Title of host publicationProceedings 13th ISEI symposium – training our immune system for health and performance
Editors Texeira et al.
Pages24-28
Number of pages5
Publication statusPublished - 2017
Event13th ISEI symposium - Coimbra, Portugal
Duration: 11 Jul 201713 Jul 2017

Conference

Conference13th ISEI symposium
CountryPortugal
CityCoimbra
Period11/07/1713/07/17

Fingerprint Dive into the research topics of 'Exercise and the brain.'. Together they form a unique fingerprint.

Cite this