Effects of chronic treadmill running on neurogenesis in the dentate gyrus of the hippocampus of adult rat

Can exercise benefits be harnessed with drugs? A new way to combat neurodegenerative diseases by boosting neurogenesis

Adult hippocampal neurogenesis (AHN) is affected by multiple factors, such as enriched environment, exercise, ageing, and neurodegenerative disorders. Neurodegenerative disorders can impair AHN, leading to progressive neuronal loss and cognitive decline. Compelling evidence suggests that individuals engaged in regular exercise exhibit higher production of proteins that are essential for AHN and memory. Interestingly, specific molecules that mediate the effects of exercise have shown effectiveness in promoting AHN and cognition in different transgenic animal models. Despite these advancements, the precise mechanisms by which exercise mimetics induce AHN remain partially understood. Recently, some novel exercise molecules have been tested and the underlying mechanisms have been proposed, involving intercommunications between multiple organs such as muscle-brain crosstalk, liver-brain crosstalk, and gut-brain crosstalk. In this review, we will discuss the current evidence regarding the effects and potential mechanisms of exercise mimetics on AHN and cognition in various neurological disorders. Opportunities, challenges, and future directions in this research field are also discussed.

Physical exercise restores adult neurogenesis deficits induced by simulated microgravity

Cognitive impairments have been reported in astronauts during spaceflights and documented in ground-based models of simulated microgravity (SMG) in animals. However, the neuronal causes of these behavioral effects remain largely unknown. We explored whether adult neurogenesis, known to be a crucial plasticity mechanism supporting memory processes, is altered by SMG. Adult male Long-Evans rats were submitted to the hindlimb unloading model of SMG. We studied the proliferation, survival and maturation of newborn cells in the following neurogenic niches: the subventricular zone (SVZ)/olfactory bulb (OB) and the dentate gyrus (DG) of the hippocampus, at different delays following various periods of SMG. SMG exposure for 7 days, but not shorter periods of 6 or 24 h, resulted in a decrease of newborn cell proliferation restricted to the DG. SMG also induced a decrease in short-term (7 days), but not long-term (21 days), survival of newborn cells in the SVZ/OB and DG. Physical exercise, used as a countermeasure, was able to reverse the decrease in newborn cell survival observed in the SVZ and DG. In addition, depending on the duration of SMG periods, transcriptomic analysis revealed modifications in gene expression involved in neurogenesis. These findings highlight the sensitivity of adult neurogenesis to gravitational environmental factors during a transient period, suggesting that there is a period of adaptation of physiological systems to this new environment.

Voluntary exercise during puberty promotes spatial memory and hippocampal DG/CA3 synaptic transmission in mice

Physical exercise has been shown to have an impact on memory and hippocampal function across different age groups. Nevertheless, the influence and mechanisms underlying how voluntary exercise during puberty affects memory are still inadequately comprehended. This research aims to examine the impacts of self-initiated physical activity throughout adolescence on spatial memory. Developing mice were exposed to a 4-wk voluntary wheel running exercise protocol, commencing at the age of 30 d. After engaging in voluntary wheel running exercise during development, there was an enhancement in spatial memory. Moreover, hippocampal dentate gyrus and CA3 neurons rather than CA1 neurons exhibited an increase in the miniature excitatory postsynaptic currents and miniature inhibitory postsynaptic currents. In addition, there was an increase in the expression of NR2A/NR2B subunits of N-methyl-D-aspartate receptors and α1GABAA subunit of gamma-aminobutyric acid type A receptors, as well as dendritic spine density, specifically within dentate gyrus and CA3 regions rather than CA1 region. The findings suggest that voluntary exercise during development can enhance spatial memory in mice by increasing synapse numbers and improving synaptic transmission in hippocampal dentate gyrus and CA3 regions, but not in CA1 region. This study sheds light on the neural mechanisms underlying how early-life exercise improves cognitive function.

The different cell-specific mechanisms of voluntary exercise and forced exercise in the nucleus accumbens

Physical inactivity is a global epidemic. People who take the initiative to exercise will feel pleasure during the exercise process and stick with it for a long time, while people who passively ask for exercise will feel pain and cannot stick with it. However, the neural mechanisms underlying voluntary and forced exercise remain unclear. Here, we report that voluntary running increased the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSC) but decreased membrane excitability in D1R-MSNs, whereas D2R-MSNs did not change in mEPSC and membrane excitability. Forced running increased the frequency of mEPSC and membrane excitability in D2R-MSNs, but D1R-MSNs did not change, which may be the mechanism by which forced exercise has a non-rewarding effect. These findings provide new insights into how voluntary and forced exercise mediate reward and non-reward effects.

Molecular mechanisms underlying physical exercise-induced brain BDNF overproduction

Accumulating evidence supports that physical exercise (EX) is the most effective non-pharmacological strategy to improve brain health. EX prevents cognitive decline associated with age and decreases the risk of developing neurodegenerative diseases and psychiatric disorders. These positive effects of EX can be attributed to an increase in neurogenesis and neuroplastic processes, leading to learning and memory improvement. At the molecular level, there is a solid consensus to involve the neurotrophin brain-derived neurotrophic factor (BDNF) as the crucial molecule for positive EX effects on the brain. However, even though EX incontestably leads to beneficial processes through BDNF expression, cellular sources and molecular mechanisms underlying EX-induced cerebral BDNF overproduction are still being elucidated. In this context, the present review offers a summary of the different molecular mechanisms involved in brain's response to EX, with a specific focus on BDNF. It aims to provide a cohesive overview of the three main mechanisms leading to EX-induced brain BDNF production: the neuronal-dependent overexpression, the elevation of cerebral blood flow (hemodynamic hypothesis), and the exerkine signaling emanating from peripheral tissues (humoral response). By shedding light on these intricate pathways, this review seeks to contribute to the ongoing elucidation of the relationship between EX and cerebral BDNF expression, offering valuable insights into the potential therapeutic implications for brain health enhancement.

Rewarded Maze Training Increases Approach Behavior in Rats Through Neurogenesis-Dependent Growth of Ventral Hippocampus-Prelimbic Circuits

Background

Learning complex navigation routes increases hippocampal volume in humans, but it is not clear whether this growth impacts behaviors outside the learning situation or what cellular mechanisms are involved.

Methods

We trained rats with pharmacogenetic suppression of adult neurogenesis and littermate controls in 3 mazes over 3 weeks and tested novelty approach behavior several days after maze exposure. We then measured hippocampus and prelimbic cortex volumes using magnetic resonance imaging and assessed neuronal and astrocyte morphology. Finally, we investigated the activation and behavioral role of the ventral CA1 (vCA1)-to-prelimbic pathway using immediate-early genes and DREADDs (designer receptors exclusively activated by designer drugs).

Results

Maze training led to volume increase of both the vCA1 region of the hippocampus and the prelimbic region of the neocortex compared with rats that followed fixed paths. Growth was also apparent in individual neurons and astrocytes in these 2 regions, and behavioral testing showed increased novelty approach in maze-trained rats in 2 different tests. Suppressing adult neurogenesis prevented the effects on structure and approach behavior after maze training without affecting maze learning itself. The vCA1 neurons projecting to the prelimbic area were more activated by novelty in maze-trained animals, and suppression of this pathway decreased approach behavior.

Conclusions

Rewarded navigational learning experiences induce volumetric and morphologic growth in the vCA1 and prelimbic cortex and enhance activation of the circuit connecting these 2 regions. Both the structural and behavioral effects of maze training require ongoing adult neurogenesis, suggesting a role for new neurons in experience-driven increases in novelty exploration.

Effect of physical activity intervention on cognitive function in China: A cluster randomized trial

INTRODUCTION

Current randomized trial evidence on the effect of physical activity (PA) intervention on cognitive function is scarce and mainly found in well-educated populations, limiting its generalizability. Furthermore, the modification effect of education levels remains understudied. We conducted a cluster randomized trial to evaluate the effects of PA intervention on cognitive function in a general older population, and whether education modifies such effects.

METHODS

Eight villages were randomized to the intervention (four villages, n = 240) or the control (four villages, n = 271). The intervention group received an 8-week multilevel PA intervention based on a socio-ecological model, while the control did not. The intervention has been condensed to three levels with activities occurring at the individual (telephone counseling, printed material, and training sessions), interpersonal (peer group), and community levels (group sharing and coaching). The primary outcome was changes in global cognition (overall cognitive function) measured by the Telephone Interview for Cognitive Status (TICS-10) at 12-month follow-up. Repeated measurements were modeled using the linear mixed model, which assumed that the missing values were missing at random.

RESULTS

The mean age was 70.94 years (standard deviation 5.71) and 55.6% were women. Compared to the control, the orientation improved from baseline at 12-month follow-up (0.24 points [95% confidence interval (CI), 0.03 to 0.46 points; P = 0.03]). Stratified analysis showed that the global cognition and orientation improved at 12-month follow-up among illiterate participants in the intervention (for global cognition, mean difference, 0.57 points [95% CI, 0.03 to 1.10], P = 0.04; for orientation, mean difference, 0.31 points [95% CI, 0.04 to 0.58], P = 0.03).

DISCUSSION

These results confirm the improvements in orientation in older adults, as well as in global cognition and orientation in the illiterate at 12-month follow-up.

Effectiveness and acceptability of non-pharmacological interventions in people with mild cognitive impairment: Overview of systematic reviews and network meta-analysis

BACKGROUND

To explore effectiveness and acceptability of non-pharmacological interventions in mild cognitive impairment (MCI).

METHODS

Overview of systematic reviews and network meta-analysis were conducted. Systematic reviews (SRs) were searched via seven databases from June 2015 to June 2020. Randomized controlled trials (RCTs) were retrieved. The Methodological quality was assessed by AMSTAR 2 and RoB 2. Outcomes were effectiveness and acceptability measured by standardized mean differences (SMDs) and odd ratios (ORs) with 95% confidence interval (CI). Pairwise meta-analysis was first conducted, followed by network meta-analysis.

RESULTS

A total of 22 SRs and 42 RCTs with 4401 participants were included. The methodological quality of included SRs and RCTs were moderate. There were four interventions, with three types of physical activity (aerobic, muscle-strengthening, and mind-body), three types of cognitive (rehearsal-based, compensatory, and mixed), multicomponent (physical and cognitive component), and nutrition intervention. No significant inconsistency was identified. Regarding intervention effectiveness, muscle-strengthening (SMDs 0.87, 95% CI 0.31-1.43; rank 1), mind-body (0.76, 0.38-1.14; rank 2) and aerobic (0.34, 0.13-0.50; rank 3) were significantly better than the control group and there was no significant difference among these types of intervention . Cognitive intervention of rehearsal-based (1.33, 0.30-2.35; rank 1) and mixed (0.55, 0.00-1.11; rank 2) were significantly better than the control group and there was no significant difference among these types of intervention. Multicomponent intervention (0.32, 0.02-0.62) were significantly better than the control group but not better than the single component group. Regarding acceptability, there was no significant difference among types of intervention.

CONCLUSION

Physical activity, cognitive, and multicomponent intervention could be provided regardless of their types and acceptability due to their effectiveness on improved cognitive function for people with MCI.

Short-Term, Voluntary Exercise Affects Morpho-Functional Maturation of Adult-Generated Neurons in Rat Hippocampus

Physical exercise is a well-proven neurogenic stimulus, promoting neuronal progenitor proliferation and affecting newborn cell survival. Besides, it has beneficial effects on brain health and cognition. Previously, we found that three days of physical activity in a very precocious period of adult-generated granule cell life is able to antedate the appearance of the first GABAergic synaptic contacts and increase T-type Ca²⁺ channel expression. Considering the role of GABA and Ca²⁺ in fostering neuronal maturation, in this study, we used short-term, voluntary exercise on a running wheel to investigate if it is able to induce long-term morphological and synaptic changes in newborn neurons. Using adult male rats, we found that: (i) three days of voluntary physical exercise can definitively influence the morpho-functional maturation process of newborn granule neurons when applied very early during their development; (ii) a significant percentage of new neurons show more mature morphological characteristics far from the end of exercise protocol; (iii) the long-term morphological effects result in enhanced synaptic plasticity. Present findings demonstrate that the morpho-functional changes induced by exercise on very immature adult-generated neurons are permanent, affecting the neuron maturation and integration in hippocampal circuitry. Our data contribute to underpinning the beneficial potential of physical activity on brain health, also performed for short times.

Combination of magnesium supplementation with treadmill exercise improves memory deficit in aged rats by enhancing hippocampal neurogenesis and plasticity: a functional and histological study

This study aimed to investigate the possible ameliorative effects of co-supplementation with Mg²⁺ and treadmill exercise on memory deficit in aged rats. Fifty male albino rats (10 young and 40 aged rats) were divided into 5 groups (10 rats/group): young, aged sedentary, aged exercised, aged Mg²⁺-supplemented, and aged exercised and Mg²⁺-supplemented. Memory was assessed using the Y-maze and novel object recognition tests. Plasma samples were collected for measurement of C-reactive protein (CRP). Subsequently, brain malondialdehyde and catalase levels were measured. Histological and immunohistochemical analyses of the hippocampi were performed. Our results showed impaired memory in aged sedentary rats, with significantly elevated plasma CRP and brain malondialdehyde levels and decreased brain catalase. The hippocampus of aged sedentary rats showed cellular degeneration, downregulation of synaptophysin (SYP) and proliferating cell nuclear antigen (PCNA), and upregulation of glial fibrillary acidic protein (GFAP) and caspase-3. Mg²⁺ supplementation and/or treadmill exercise significantly improved memory tests in aged rats, which could be explained by the upregulation of hippocampal SYP and PCNA expression and downregulation of GFAP and caspase-3 expression with antioxidant and anti-inflammatory mechanisms. The combined therapy had a better effect than both treatments alone, confirming the role of Mg²⁺ supplementation with physical exercise in enhancing age-related memory deficit. Novelty: Magnesium supplementation with treadmill exercise improves memory deficit in aged rats. The possible mechanisms are upregulation of the hippocampal synaptophysin and PCNA, downregulation of GFAP and caspase-3, the antioxidant and anti-inflammatory mechanisms.

Exercise rather than fluoxetine promotes oligodendrocyte differentiation and myelination in the hippocampus in a male mouse model of depression

Although selective serotonin reuptake inhibitor (SSRI) systems have been meaningfully linked to the clinical phenomena of mood disorders, 15-35% of patients do not respond to multiple SSRI interventions or even experience an exacerbation of their condition. As we previously showed, both running exercise and fluoxetine reversed depression-like behavior. However, whether exercise reverses depression-like behavior more quickly than fluoxetine treatment and whether this rapid effect is achieved via the promotion of oligodendrocyte differentiation and/or myelination in the hippocampus was previously unknown. Sixty male C57BL/6 J mice were used in the present study. We subjected mice with unpredictable chronic stress (UCS) to a 4-week running exercise trial (UCS + RN) or intraperitoneally injected them with fluoxetine (UCS + FLX) to address these uncertainties. At the behavioral level, mice in the UCS + RN group consumed significantly more sugar water in the sucrose preference test (SPT) at the end of the 7th week than those in the UCS group, while those in the UCS + FLX group consumed significantly more sugar water than mice in the UCS group at the end of the 8th week. The unbiased stereological results and immunofluorescence analyses revealed that running exercise, and not fluoxetine treatment, increased the numbers of CC1⁺ and CC1⁺/Olig2⁺/BrdU⁺ oligodendrocytes in the CA1 subfield in depressed mice exposed to UCS. Moreover, running exercise rather than fluoxetine increased the level of myelin basic protein (MBP) and the G-ratio of myelinated nerve fibers in the CA1 subfield in the UCS mouse model. Unlike fluoxetine, exercise promoted hippocampal myelination and oligodendrocyte differentiation and thus has potential as a therapeutic strategy to reduce depression-like behaviors induced by UCS.

Neuroplastic Effect of Exercise Through Astrocytes Activation and Cellular Crosstalk

Physical exercise is an effective therapy for neurorehabilitation. Exercise has been shown to induce remodeling and proliferation of astrocyte. Astrocytes potentially affect the recruitment and function of neurons; they could intensify responses of neurons and bring more neurons for the process of neuroplasticity. Interactions between astrocytes, microglia and neurons modulate neuroplasticity and, subsequently, neural circuit function. These cellular interactions promote the number and function of synapses, neurogenesis, and cerebrovascular remodeling. However, the roles and crosstalk of astrocytes with neurons and microglia and any subsequent neuroplastic effects have not been studied extensively in exercise-induced settings. This article discusses the impact of physical exercise on astrocyte proliferation and highlights the interplay between astrocytes, microglia and neurons. The crosstalk between these cells may enhance neuroplasticity, leading to the neuroplastic effects of exercise.

Lifestyle-dependent microglial plasticity: training the brain guardians

Lifestyle is one of the most powerful instruments shaping mankind; the lifestyle includes many aspects of interactions with the environment, from nourishment and education to physical activity and quality of sleep. All these factors taken in complex affect neuroplasticity and define brain performance and cognitive longevity. In particular, physical exercise, exposure to enriched environment and dieting act through complex modifications of microglial cells, which change their phenotype and modulate their functional activity thus translating lifestyle events into remodelling of brain homoeostasis and reshaping neural networks ultimately enhancing neuroprotection and cognitive longevity.

Neuroprotective Effects of Physical Activity via the Adaptation of Astrocytes

The multifold benefits of regular physical exercise have been largely demonstrated in human and animal models. Several studies have reported the beneficial effects of physical activity, both in peripheral tissues and in the central nervous system (CNS). Regular exercise improves cognition, brain plasticity, neurogenesis and reduces the symptoms of neurodegenerative diseases, making timeless the principle of “mens sana in corpore sano” (i.e., a healthy mind in a healthy body). Physical exercise promotes morphological and functional changes in the brain, acting not only in neurons but also in astrocytes, which represent the most numerous glial cells in the brain. The multiple effects of exercise on astrocytes comprise the increased number of new astrocytes, the maintenance of basal levels of catecholamine, the increase in glutamate uptake, the major release of trophic factors and better astrocytic coverage of cerebral blood vessels. The purpose of this review is to highlight the effects of exercise on brain function, emphasize the role of astrocytes in the healthy CNS, and provide an update for a better understanding of the effects of physical exercise in the modulation of astrocyte function.

Understanding the role of aerobic fitness, spatial learning, and hippocampal subfields in adolescent males

Physical exercise during adolescence, a critical developmental window, can facilitate neurogenesis in the dentate gyrus and astrogliogenesis in Cornu Ammonis (CA) hippocampal subfields of rats, and which have been associated with improved hippocampal dependent memory performance. Recent translational studies in humans also suggest that aerobic fitness is associated with hippocampal volume and better spatial memory during adolescence. However, associations between fitness, hippocampal subfield morphology, and learning capabilities in human adolescents remain largely unknown. Employing a translational study design in 34 adolescent males, we explored the relationship between aerobic fitness, hippocampal subfield volumes, and both spatial and verbal memory. Aerobic fitness, assessed by peak oxygen utilization on a high-intensity exercise test (VO2 peak), was positively associated with the volumetric enlargement of the hippocampal head, and the CA1 head region specifically. Larger CA1 volumes were also associated with spatial learning on a Virtual Morris Water Maze task and verbal learning on the Rey Auditory Verbal Learning Test, but not recall memory. In line with previous animal work, the current findings lend support for the long-axis specialization of the hippocampus in the areas of exercise and learning during adolescence.

Mitigating the negative impacts of aging on cognitive function; modifiable factors associated with increasing cognitive reserve

Research suggests that social, physical, and cognitively challenging activities during lifetime, could mitigate the negative effects of aging on cognitive function. This effect is explained by the increased cognitive reserve (CR) resulting from such factors; in fact, such activities, by altering structural and functional properties of the human brain, equip one with more effective compensatory mechanisms to resist brain damage before the presentation of severe clinical symptoms. Therefore, applying appropriate modifications in one's lifestyle and activities may be effective in lowering the risk of developing dementia and cognitive dysfunction in old age, especially in brain areas that are susceptible to aging. In this paper, we are going to review relevant studies discussing the association between important modifiable factors, known as CR proxies (i.e., educational attainment, occupational complexity, physical activity, social engagement, bilingualism, leisure activities, and Mediterranean diet), and different domains of cognitive function, which are affected either in the process of healthy aging or neurodegenerative diseases.

Multimodal Imaging Brain Markers in Early Adolescence Are Linked with a Physically Active Lifestyle

The World Health Organization promotes physical exercise and a healthy lifestyle as means to improve youth development. However, relationships between physical lifestyle and human brain development are not fully understood. Here, we asked whether a human brain-physical latent mode of covariation underpins the relationship between physical activity, fitness, and physical health measures with multimodal neuroimaging markers. In 50 12-year old school pupils (26 females), we acquired multimodal whole-brain MRI, characterizing brain structure, microstructure, function, myelin content, and blood perfusion. We also acquired physical variables measuring objective fitness levels, 7 d physical activity, body mass index, heart rate, and blood pressure. Using canonical correlation analysis, we unravel a latent mode of brain-physical covariation, independent of demographics, school, or socioeconomic status. We show that MRI metrics with greater involvement in this mode also showed spatially extended patterns across the brain. Specifically, global patterns of greater gray matter perfusion, volume, cortical surface area, greater white matter extra-neurite density, and resting state networks activity covaried positively with measures reflecting a physically active phenotype (high fit, low sedentary individuals). Showing that a physically active lifestyle is linked with systems-level brain MRI metrics, these results suggest widespread associations relating to several biological processes. These results support the notion of close brain-body relationships and underline the importance of investigating modifiable lifestyle factors not only for physical health but also for brain health early in adolescence.SIGNIFICANCE STATEMENT An active lifestyle is key for healthy development. In this work, we answer the following question: How do brain neuroimaging markers relate with young adolescents' level of physical activity, fitness, and physical health? Combining advanced whole-brain multimodal MRI metrics with computational approaches, we show a robust relationship between physically active lifestyles and spatially extended, multimodal brain imaging-derived phenotypes. Suggesting a wider effect on brain neuroimaging metrics than previously thought, this work underlies the importance of studying physical lifestyle, as well as other brain-body relationships in an effort to foster brain health at this crucial stage in development.

The positive effects of running exercise on hippocampal astrocytes in a rat model of depression

Running exercise has been shown to alleviate depressive symptoms, but the mechanism of its antidepressant effect is still unclear. Astrocytes are the predominant cell type in the brain and perform key functions vital to central nervous system (CNS) physiology. Mounting evidence suggests that changes in astrocyte number in the hippocampus are closely associated with depression. However, the effects of running exercise on astrocytes in the hippocampus of depression have not been investigated. Here, adult male rats were subjected to chronic unpredictable stress (CUS) for 5 weeks followed by treadmill running for 6 weeks. The sucrose preference test (SPT) was used to assess anhedonia of rats. Then, immunohistochemistry and modern stereological methods were used to precisely quantify the total number of glial fibrillary acidic protein (GFAP)⁺ astrocytes in each hippocampal subregion, and immunofluorescence was used to quantify the density of bromodeoxyuridine (BrdU)⁺ and GFAP⁺ cells in each hippocampal subregion. We found that running exercise alleviated CUS-induced deficit in sucrose preference and hippocampal volume decline, and that CUS intervention significantly reduced the number of GFAP⁺ cells and the density of BrdU⁺/GFAP⁺ cells in the hippocampal CA1 region and dentate gyrus (DG), while 6 weeks of running exercise reversed these decreases. These results further confirmed that running exercise alleviates depressive symptoms and protects hippocampal astrocytes in depressed rats. These findings suggested that the positive effects of running exercise on astrocytes and the generation of new astrocytes in the hippocampus might be important structural bases for the antidepressant effects of running exercise.

Voluntary wheel running promotes improvements in biomarkers associated with neurogenic activity in adult male rats

In rodents, hippocampal neurogenesis and synaptogenesis phenomena are affected by exercise. However, the role of exercise parameters such as intensity, duration, and mode on molecular mechanisms involved in these processes has not been elucidated. In this study, we evaluated the effects of different intensities and modes of running on the expression of genes contributing to neuronal differentiation and synapse formation in the hippocampus of adult male rats. Adult male Wistar rats (n = 24) were randomly divided into control, low-intensity running (LIR), high-intensity running (HIR), and the voluntary wheel running (WR) conditions. Changes in the expression of microRNA-124 (miR-124), microRNA-132 (miR-132), and their respective targets, were analyzed using quantitative RT-PCR and Western blotting techniques. Our results showed that WR compared to treadmill running increased miR-124 and miR-132 expression, while reducing the expression of their respective targets, glucocorticoid receptor (GR), SRY-Box 9 (SOX9), and GTP-activated protein P250 (P250GAP). Differences in expression levels were statistically significant (ps < 0.05), except for the expression of GR in HIR (P = 0.09). Moreover, the expression level of gene coding for the transcription factor cAMP-response element binding protein (CREB) was significantly higher in the WR group compared to the treadmill running groups (P = 0.001). Western blotting techniques indicated that the level of the CREB protein was higher in WR compared to the other groups qualitatively. These findings demonstrated a more dramatic effect for voluntary running on biomarkers that are associated with stimulating neurogenesis and synapse formation in the hippocampus of male rats compared with forced treadmill running. In addition, greater positive effects were observed for lower-intensity treadmill running as compared with high-intensity running.

Electrically stimulated hind limb muscle contractions increase adult hippocampal astrogliogenesis but not neurogenesis or behavioral performance in male C57BL/6J mice

Regular exercise is crucial for maintaining cognitive health throughout life. Recent evidence suggests muscle contractions during exercise release factors into the blood which cross into the brain and stimulate adult hippocampal neurogenesis. However, no study has tested whether muscle contractions alone are sufficient to increase adult hippocampal neurogenesis and improve behavioral performance. Adult male, C57BL/6J mice were anesthetized and exposed to bilateral hind limb muscle contractions (both concentric and eccentric) via electrical stimulation (e-stim) of the sciatic nerve twice a week for 8 weeks. Each session lasted approximately 20 min and consisted of a total of 40 muscle contractions. The control group was treated similarly except without e-stim (sham). Acute neuronal activation of the dentate gyrus (DG) using cFos immunohistochemistry was measured as a negative control to confirm that the muscle contractions did not activate the hippocampus, and in agreement, no DG activation was observed. Relative to sham, e-stim training increased DG volume by approximately 10% and astrogliogenesis by 75%, but no difference in neurogenesis was detected and no improvement in behavioral performance was observed. E-stim also increased astrogliogenesis in CA1/CA2 hippocampal subfields but not in the cortex. Results demonstrate that muscle contractions alone, in absence of DG activation, are sufficient to increase adult hippocampal astrogliogenesis, but not neurogenesis or behavioral performance in mice.

The Neuroprotective Effects of Exercise on Cognitive Decline: A Preventive Approach to Alzheimer Disease

Alzheimer's disease (AD) is a progressive disorder that causes brain cells to slowly degenerate and die. This leads to a continuous decline in thinking, behavioral and social skills that disrupts a person's ability to function independently. AD is the most common cause of dementia globally. Neuroinflammation caused by intracellular neurofibrillary tangles and extracellular amyloid deposits leads to atrophy of brain cells especially the hippocampus, which is associated with memory formation. This atrophy leads to dementia and cognitive decline. Among the many preventive factors being studied, exercise is thought to play a vital role in not only preventing the pre-clinical stage of AD but also slowing the clinical progression of AD. It is also deployed as a treatment option for late-stage AD along with pharmacological treatment options. Various studies and clinical trials in both human and animal models are of the opinion that exercise slows the onset and progression of cognitive decline in AD patients. Some studies suggest that this effect is due to a decrease in neurofibrillary tangles and amyloid deposits in brain parenchyma. Others suggest that exercise causes an increase in angiogenesis, neurogenesis, and synaptogenesis mainly due to an increase in blood flow, brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), hormones, and second messengers. 

Treadmill running attenuates neonatal hypoxia induced adult depressive symptoms and promoted hippocampal neural stem cell differentiation via modulating AMPK-mediated mitochondrial functions

Neonatal hypoxia can induce the persisting brain dysfunctions and subsequently result in the behavioral abnormalities in adulthood. Improving mitochondrial functions were suggested as the effective strategy for brain functional recovery. In this study, we tested the effects of physical exercise, a well-established way benefits mitochondrion, for its functions to prevent hypoxia induced adult behavioral dysfunctions and the underlying molecular mechanism. Mice was induced with hypoxia and treadmill running were then administrated until the adulthood. The treadmill running resulted in the improved behavioral performance in depressive and anxiety tests together with the enhancement of hippocampal neurogenesis. We then detected treadmill running restored the mitochondrial morphology in adult neural stem cells (NSCs) as well as the ATP production in hippocampal tissue. In addition, activity of AMPK, which playing key roles in regulating mitochondrial functions, was also elevated by treadmill running. Blockage of AMPK with selective inhibitor compound C prohibited effects of treadmill running in attenuating neonatal hypoxia induced neurogenic impairment and antidepressant behavioral deficits in adulthood. In conclusion, treadmill running could prevent neonatal hypoxia induced adult antidepressant dysfunctions and neurogenic dampening via AMPK-mediated mitochondrial regulation.

Shaping the adult brain with exercise during development: Emerging evidence and knowledge gaps

Exercise is known to produce a myriad of positive effects on the brain, including increased glia, neurons, blood vessels, white matter and dendritic complexity. Such effects are associated with enhanced cognition and stress resilience in humans and animal models. As such, exercise represents a positive experience with tremendous potential to influence brain development and shape an adult brain capable of responding to life's challenges. Although substantial evidence attests to the benefits of exercise for cognition in children and adolescents, the vast majority of existing studies examine acute effects. Nonetheless, there is emerging evidence indicating that exercise during development has positive cognitive and neural effects that last to adulthood. There is, therefore, a compelling need for studies designed to determine the extent to which plasticity driven by developmental exercise translates into enhanced brain health and function in adulthood and the underlying mechanisms. Such studies are particularly important given that modern Western society is increasingly characterized by sedentary behavior, and we know little about how this impacts the brain's developmental trajectory. This review synthesizes current literature and outlines significant knowledge gaps that must be filled in order to elucidate what exercise (or lack of exercise) during development contributes to the health and function of the adult brain.

Therapeutic effects of aerobic exercise on EEG parameters and higher cognitive functions in mild cognitive impairment patients

BACKGROUND

Mild cognitive impairment (MCI) is becoming an emerging problem for developing countries where there is an increase in expected age. There is no specific curative therapeutic treatment available for these patients.

OBJECTIVE

The objective of this study was to evaluate short and long-term changes in the electroencephalogram (EEG) parameters and cognition of MCI patients with aerobic exercises.

METHODS

A randomized controlled trial was conducted on 40 patients which were randomly divided into two groups, 'aerobic exercise treatment group (n = 21)' and 'no-aerobic control group (n = 19)'. Short-term effects of exercise were measured after single session of exercise and long-term effects were measured after an 18 sessions (6 weeks) treatment. The outcomes which were measured were, electroenphelogram paramaters (slowness and complexity of the EEG) and cognitive functions (using mini-mental state examination (MMSE), Montreal cognitive assessment (MoCA), and trail making test (TMT) A and B).

RESULTS

After one session of aerobic exercise there were significant improvements in slowness (delta waves; 0.678 ± 0.035 vs 0.791 ± 0.033; p = .015) and complexity (0.601 ± 0.051 vs 0.470 ± 0.042; p = .027) of the EEG in aerobic exercise treated group as compared to no-aerobic exercise group. After six weeks there were significant improvements in slowness (delta waves; 0.581 ± 0.036 vs 0.815 ± 0.025; p = .005) and complexity (0.751 ± 0.045 vs 0.533 ± 0.046; p = .001) of the EEG in the aerobic group as compared to no-aerobic group. Moreover, significant improvements were observed in the MMSE (p = .032), MoCA (p = .036), TMT-A (p = .005), and TMT-B (p = .007) in aerobic exercise group as compared to no-aerobic group.

CONCLUSION

Aerobic exercise showed improvement in cognition after short and long-term treatment in MCI subjects and can be used as potential therapeutic candidate.

Exercise-induced enhancement of synaptic function triggered by the inverse BAR protein, Mtss1L

Exercise is a potent enhancer of learning and memory, yet we know little of the underlying mechanisms that likely include alterations in synaptic efficacy in the hippocampus. To address this issue, we exposed mice to a single episode of voluntary exercise, and permanently marked activated mature hippocampal dentate granule cells using conditional Fos-TRAP mice. Exercise-activated neurons (Fos-TRAPed) showed an input-selective increase in dendritic spines and excitatory postsynaptic currents at 3 days post-exercise, indicative of exercise-induced structural plasticity. Laser-capture microdissection and RNASeq of activated neurons revealed that the most highly induced transcript was Mtss1L, a little-studied I-BAR domain-containing gene, which we hypothesized could be involved in membrane curvature and dendritic spine formation. shRNA-mediated Mtss1L knockdown in vivo prevented the exercise-induced increases in spines and excitatory postsynaptic currents. Our results link short-term effects of exercise to activity-dependent expression of Mtss1L, which we propose as a novel effector of activity-dependent rearrangement of synapses.

The role of astrocytes on the effects of exercise on episodic memory function

This review discusses the potential role that glial cells may play in influencing the relationship between exercise and episodic memory function. A narrative review methodology is employed. Herein, the different types of glial cells, their implications in subserving episodic memory function, and how exercise can modulate glial cell activity, particularly astrocyte functionality, are discussed. Although additional experimental work is needed, astrocytes appear to play an important role in the exercise-memory interaction. Exercise may increase astrocytic size, attenuate astrogliodegeneration, improve astrocytic aquaporin-4 expression, and increase astrocytic transporter levels. These effects, in turn, may help to increase the number of synapses that neurons form, increase the number of synaptic structures, and increase presynaptic function and postsynaptic receptor localization. Ultimately, these effects may help influence long-term potentiation and episodic memory function.

Lifetime physical activity and late-life cognitive function: the Rancho Bernardo study

BACKGROUND

physical activity in older age has been associated with better cognitive function, but the role of earlier life physical activity is less well understood.

OBJECTIVE

determine associations between physical activity throughout the lifespan and cognitive function in older age.

DESIGN

cross-sectional study.

SETTING

the Rancho Bernardo Study of Healthy Aging in southern California.

SUBJECTS

A total of 1,826 community-dwelling men and women (60-99 years) who attended a research visit in 1988-92.

METHODS

participants underwent cognitive testing at older age, and reported physical activity as a teenager, at age 30 years, 50 years and currently. For each time-point, participants were classified as regularly active (3+ times/week) or inactive.

RESULTS

regular physical activity was associated with better cognitive function, with physical activity at older ages showing the strongest associations. Physical activity in older age was associated with better global cognitive function, executive function and episodic memory, regardless of intensity. Intense physical activity in teenage years was associated with better late-life global cognitive function in women. Teenage physical activity interacted with older age physical activity on executive function; those active at both periods performed better than those active at only one period. Similar patterns of associations were observed after excluding individuals with poor health.

CONCLUSIONS

regular physical activity in older age, regardless of intensity, is associated with better cognitive function. Physical activity in teenage years may enhance cognitive reserve to protect against age-related decline in executive function. Further research is needed to assess the effect of physical activity across the lifespan on healthy brain ageing.

Effect of fine and gross motor training or motor imagery, delivered via novel or routine modes, on cognitive function

There is extensive literature linking motor activity to cognitive effects at various stages in life, promoting both development and the reduction of aging associated pathologies. It is unclear whether the benefits of this activity on the cognitive level are associated with brain functions that are necessary for their performance or recurrence of activity or type of activity itself. The aim of this study was to evaluate whether the type of motor activity (fine, gross, and motor imagery) in two modes (novel and routine) can affect cognitive functions such as attention, executive functions, and praxis in college students. A 2 × 3 factorial design with repeated measures was used without a control group and pre- and post-training evaluation. Fifty-three young people (14 men and 39 women) participated, with mean age of 18.94 years (SD = 1.61 years) and were divided into six groups. Each of the groups performed relevant training 20 minutes per day for five days depending on the group. Measures were taken pre and post-training for attention tests, attention span, working memory, visual constructive skills, procedural memory, and motor skills. The results show a "learning effect" from the exposure to the tests in measurements after training. It was also found that between groups, there is a difference in some of the variables of procedural memory (number of errors) and working memory. More extensive training could better reflect the effects of the training, and longitudinal evaluation could show the rate of change of functions. The main clinical implication could be the evaluation of training programs for recovery and motor training in cerebral plasticity having effect on the cognitive aspects.

The Multidisciplinary Approach to Alzheimer's Disease and Dementia. A Narrative Review of Non-Pharmacological Treatment

Background: Alzheimer's disease (AD) and dementia are chronic diseases with progressive deterioration of cognition, function, and behavior leading to severe disability and death. The prevalence of AD and dementia is constantly increasing because of the progressive aging of the population. These conditions represent a considerable challenge to patients, their family and caregivers, and the health system, because of the considerable need for resources allocation. There is no disease modifying intervention for AD and dementia, and the symptomatic pharmacological treatments has limited efficacy and considerable side effects. Non-pharmacological treatment (NPT), which includes a wide range of approaches and techniques, may play a role in the treatment of AD and dementia. Aim: To review, with a narrative approach, current evidence on main NPTs for AD and dementia. Methods: PubMed and the Cochrane database of systematic reviews were searched for studies written in English and published from 2000 to 2018. The bibliography of the main articles was checked to detect other relevant papers. Results: The role of NPT has been largely explored in AD and dementia. The main NPT types, which were reviewed here, include exercise and motor rehabilitation, cognitive rehabilitation, NPT for behavioral and psychological symptoms of dementia, occupational therapy, psychological therapy, complementary and alternative medicine, and new technologies, including information and communication technologies, assistive technology and domotics, virtual reality, gaming, and telemedicine. We also summarized the role of NPT to address caregivers' burden. Conclusions: Although NPT is often applied in the multidisciplinary approach to AD and dementia, supporting evidence for their use is still preliminary. Some studies showed statistically significant effect of NPT on some outcomes, but their clinical significance is uncertain. Well-designed randomized controlled trials with innovative designs are needed to explore the efficacy of NPT in AD and dementia. Further studies are required to offer robust neurobiological grounds for the effect of NPT, and to examine its cost-efficacy profile in patients with dementia.

Endurance training on rodent brain antioxidant capacity: A meta-analysis

The influence of physical exercise on brain antioxidant defense mechanisms has been studied. Nevertheless, the effect of training volume on the brain`s redox balance remains unclear. In this meta-analysis, we compared the effect of training volume on antioxidant enzymatic resource and lipid peroxidation on various brain regions. The activities of the enzymes glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and the levels of thiobarbituric acid reactive substances (TBARS) were also evaluated. The effects of training periods (weeks) and exercise duration were compared. Meta-analysis revealed that protocols over 8 weeks were associated with an increase in SOD (p =  0.0008) and CAT activities (p =  0.0001). Exercise durations for 30 and 60 min were associated with higher CAT activity (p =  0.04). Joint analysis revealed that moderate physical exercise over 4 and 8 weeks promoted a healthy enzymatic balance. However, high volumes of exercise over 8 weeks were associated with the increased antioxidant enzymatic activity, indicating higher reactive oxygen species (ROS) levels. The data also indicated that there is still limited research and inaccurate information, on the safety conditions of training periods that simulate tests of ultra resistance in humans.

Astrocytes and radial glia-like cells, but not neurons, display a nonapoptotic increase in caspase-3 expression following exercise

BACKGROUND

Exercise induces plasticity in the hippocampus, which includes increases in neurogenesis, the proliferation of new neurons, and angiogenesis, the sprouting of new capillaries from preexisting blood vessels. Following exercise, astrocytes also undergo morphological changes that parallel the events occurring in the neurovascular system. Interestingly, there have also been reports of apoptosis in the hippocampus following aerobic exercise. This experiment aimed to identify which population of hippocampal cells undergoes apoptosis after an acute bout of exercise.

METHODS

Cleaved caspase-3, a terminal protein in the apoptotic cascade, was initially used to identify apoptotic cells in the hippocampus after rats completed an acute bout of exercise. Next, the proportion of immature neurons, adult neurons, astrocytes, or radial glia-like cells expressing cleaved caspase-3 was quantified. TUNEL staining was completed as a second measure of apoptosis.

RESULTS

Following exercise, cleaved caspase-3 expression was increased in the CA1 and DG regions of the hippocampus. Cleaved caspase-3 was not highly expressed in neuronal populations, and expression was not increased in these cells postexercise. Instead, cleaved caspase-3 was predominantly expressed in astrocytes. Following exercise, there was an increased number of cleaved caspase-3 positive astrocytes in DG and CA1, and cleaved caspase-3 positive radial glia-like cells located in the subgranular zone. To determine whether cleaved caspase-3 expression in these glial cells was associated with apoptosis, a TUNEL assay was completed. TUNEL staining was negligible in all groups and did not mirror the pattern of caspase-3 labeling.

CONCLUSIONS

Cleaved caspase-3 expression was detected largely in non-neuronal cell populations, and the pattern of cleaved caspase-3 expression did not match that of TUNEL. This suggests that after exercise, cleaved caspase-3 expression may serve a nonapoptotic role in these hippocampal astrocytes and radial glia-like cells. It will be important to identify the function of exercise-induced cleaved caspase-3 expression in the future experiments.

Exercise Reduces Dopamine D1R and Increases D2R in Rats: Implications for Addiction

INTRODUCTION

Exercise has been shown to be effective for preventing and treating substance abuse in both clinical and preclinical studies. Less is known, however, regarding the underlying neurobiological mechanisms driving these changes in drug-seeking behavior. One possibility is that exercise may alter the mesolimbic dopamine pathway in such a way that makes drugs of abuse less salient and/or rewarding.

METHODS

To examine possible exercise-induced changes in dopamine signaling, male and female Lewis rats were split into exercise and sedentary groups at 8 wk of age. Exercise rats were run on a treadmill at 10 m·min, 5 d·wk, for 6 wk, whereas sedentary rats remained in their home cage. Rats were killed after the 6 wk of treatment, and their brains were used for in vitro autoradiography using [H]SCH 23,390, [H]Spiperone, and [H]WIN55,428 ligands to quantify dopamine type 1-like receptor (D1R)-like, dopamine type 2-like receptor (D2R)-like, and dopamine transporter binding, respectively.

RESULTS

Exercised rats had 18% and 21% lower D1R-like binding levels compared to sedentary rats within the olfactory tubercle and nucleus accumbens shell, respectively. In addition, male and female exercise rats showed greater D2R-like binding levels within the dorsomedial caudate putamen (30%), ventrolateral caudate putamen (24%), and ventromedial caudate putamen (27%), as well as the olfactory tubercle (19%). Greater D2R-like binding in the nucleus accumbens core (24%) and shell (25%) of exercised rats compared with sedentary rats approached significance. No effects were found for dopamine transporter binding.

CONCLUSIONS

These findings support the hypothesis that aerobic exercise results in changes in the mesolimbic pathway that could mediate exercise-induced attenuation of drug-seeking behavior.

Chronic forced exercise inhibits stress-induced reinstatement of cocaine conditioned place preference

Stress increases the likelihood of cocaine relapse in humans and animals, even following a prolonged extinction/abstinence period. Exercise has previously been shown to reduce stress and decrease the likelihood of drug dependence, while also reducing cravings in humans and inhibiting relapse behaviors due to other risk factors in rodents. The present study evaluated the efficacy of exercise to reduce stress-induced relapse to cocaine in a rodent model. Young adult female Sprague Dawley rats were tested for cocaine conditioned place preference (CPP), then split into sedentary or exercise (six weeks of one-hour daily treadmill running, five days per week) groups. Following cocaine CPP, rats were tested for extinction behavior, and then tested for stress-primed reinstatement (15 min immobilization) following the six-week intervention period. Exercise inhibited stress-induced reinstatement of cocaine CPP despite increasing serum corticosterone levels following 15 min of immobilization, suggesting that chronic aerobic exercise intervention may result in adaptations of stress pathways. These findings suggest that exercise may help prevent stress-induced drug relapse, adding to a growing body of evidence supporting the utility of exercise to combat substance abuse.

Brain-derived neurotrophic factor secreted by the cerebral endothelium: A new actor of brain function?

Low cerebral levels of brain-derived neurotrophic factor (BDNF), which plays a critical role in many brain functions, have been implicated in neurodegenerative, neurological and psychiatric diseases. Thus, increasing BDNF levels in the brain is considered an attractive possibility for the prevention/treatment of various brain diseases. To date, BDNF-based therapies have largely focused on neurons. However, given the cross-talk between endothelial cells and neurons and recent evidence that BDNF expressed by the cerebral endothelium largely accounts for BDNF levels present in the brain, it is likely that BDNF-based therapies would be most effective if they also targeted the cerebral endothelium. In this review, we summarize the available knowledge about the biology and actions of BDNF derived from endothelial cells of the cerebral microvasculature and we emphasize the remaining gaps and shortcomings.

Sex differences after environmental enrichment and physical exercise in rats when solving a navigation task

The effects of early environmental enrichment (EE) and voluntary wheel running on the preference for using a landmark or pool geometry when solving a simple spatial task in adult male and female rats were assessed. After weaning, rats were housed in same-sex pairs in enriched or standard cages (EE and control groups) for two and a half months. Then the rats were trained in a triangular-shaped pool to find a hidden platform whose location was defined in terms of these two sources of information, a landmark outside the pool and a particular corner of the pool. As expected, enriched rats reached the platform faster than control animals, and males and females did not differ. Enriched rats also performed better on subsequent test trials without the platform with the cues individually presented (either pool geometry or landmark). However, on a preference test without the platform, a clear sex difference was found: Females spent more time in an area of the pool that corresponded to the landmark, whereas males spent more time in the distinctive corner of the pool. The present EE protocol did not alter females' preference for the landmark cue. The results agree with the claim that environmental enrichment is a consequence of a reduced anxiety response (measured by thigmotaxis) during cognitive testing. A possible implication of ancestral selection pressures is discussed.

Continuous and not continuous 2-week treadmill training enhances the performance in the passive avoidance test in ischemic gerbils

This study aims to investigate the frequency and total duration effects of the 2-week treadmill training after experimental ischemic stroke in the passive avoidance test. We performed bilateral occlusion of common external carotid arteries, for five minutes, in Mongolian gerbils. The training groups were: continuous training for twelve consecutive days or not continuous training for six non-consecutive days. The groups remained in the treadmill for 15min, with the speed set at 10m/min, and the training started 24h after the stroke. In the Shuttle Box, each animal had ten trials during the Learning Session (LS), which occurred 24h before the stroke. The Retention Test (RT) occurred 24h after the stroke and started on the second, third, seventh and twelfth day after LS. After the experiments, the brains were perfused, and coronal sections of the CA1 area of the hippocampus were cut and stained with hematoxylin and eosin. ANOVA on Ranks was used for Behavioral data analysis and morphological data by percentage. Ischemic training groups showed preservation in neuron density in the CA1 area of the hippocampus, when compared to the control groups. Animals subjected to continuous training, showed a higher latency in the RT when compared to ischemic animals in both weeks [(2nd, H=39.81; P<0.05), (3rd, H=38.08; P<0.05), (7th, H=44.17; P<0.05), and (12th, H=39.55; P<0.05). Animals in the not continuous training showed higher latency in the RT, in the second week only [(2nd, H=39.81; P<0.05), (3rd, H=38.08; P<0.05), (7th, H=44.17; P<0.05), and (12th, H=39.55; P<0.05). These findings suggest that improvement of memory after stroke after treadmill training is dependent on the frequency and total duration of training.

Resistance training and hawthorn extract ameliorate cognitive deficits in streptozotocin-induced diabetic rats

It has been shown that diabetic rats display cognitive impairment. The aim of this study was to investigate the effects of resistance training and natural antioxidants on learning and memory in type 1 diabetic rats. For this purpose, fifty male Wistar rats were randomly divided into five groups: (i) Control (Con, n=10), (ii) Diabetic (D, n=10), (iii) Diabetic+Resistance training (DRT, n=10), (iv) Diabetic+natural antioxidants (DHE, n=10), and (v) Diabetic+Resistance training+ natural antioxidants (DRH, n=10). Climbing the ladder for a period of 5days/week for 10 consecutive weeks was considered as the resistance training model in our study. Natural antioxidants (100mg/kg per day) were administered to natural antioxidant groups for a period of 10 weeks. Moreover, spatial and passive avoidance learning and memory function were evaluated by Morris Water Maze (MWM) and shuttle box tests. The results showed that, mean of total escape latency decreased 25% (P<0.0001) in the DRH group compared with the D group in MWM. The percentage of time spent in the target quadrant identically decreased (34%) in the D and DHE groups compared with the Con group (p=0.001). In this regard, time spent in the dark Compartment (TDC) respectively rose 86% and 95% in the D and DHE groups compared with the Con group (p<0.05), and decreased 88% in the DRT and DRH groups compared with the D group in the shuttle box test (p<0.05). Furthermore, we noticed that total antioxidant capacity increase and lipid peroxidation decrease in response to the treatments in the diabetic rats as well. Therefore, the current study indicated that exercise training and natural antioxidants synergistically ameliorated learning and memory deficits in type 1 diabetic rats via reducing oxidative stress. Hence, it may propose a potential role of resistance training and natural antioxidants as an adjuvant therapy for the prevention and treatment of diabetic complications.

Running Changes the Brain: the Long and the Short of It

Exercise is a simple intervention that profoundly benefits cognition. In rodents, running increases neurogenesis in the hippocampus, a brain area important for memory. We describe the dynamic changes in new neuron number and afferent connections throughout their maturation. We highlight the effects of exercise on the neurotransmitter systems involved, with a focus on the role of glutamate and acetylcholine in the initial development of new neurons in the adult brain.

Exercise pattern and distance differentially affect hippocampal and cerebellar expression of FLK-1 and FLT-1 receptors in astrocytes and blood vessels

Aerobic exercise benefits the body and brain. In the brain, benefits include neuroprotection and improved cognition. These exercise-induced changes are attributed in part to angiogenesis: the growth of new capillaries from preexisting vessels. One critical factor involved in the regulation of angiogenesis is VEGF and its receptors Flk-1 and Flt-1. Although exercise is generally found to be beneficial, there are wide variations in exercise regimens across experiments. This study standardized some of these variations. Rats were assigned to a voluntary or a forced wheel running exercise condition. Within each condition, animals ran for either a long (1000m) or short distance (500m) for up to 24h. Additionally, one voluntary group had unrestricted access to the wheels for the full 24h. Exercising animals were then compared to inactive controls, based on unbiased stereological quantification of Flk-1 and Flt-1 immunohistochemical labeling in the hippocampus and cerebellum. Findings indicated that voluntary exercise, but not forced exercise, could significantly increase Flk-1 and Flt-1 expression in the hippocampus. Interestingly, Flk-1 expression was elevated in astrocytes and Flt-1 in vessels. In the cerebellum long distance forced exercise resulted in the least Flk-1 expression compared to other conditions, and Flt-1 expression in exercising animals either did not change or was suppressed relative to inactive controls.

Long-term voluntary exercise prevents post-weaning social isolation-induced cognitive impairment in rats

This study aimed to determine the effect of exercise on locomotion, anxiety-related behavior, learning, and memory in socially isolated post-weaning rats, as well as the correlation between exercise and the concentration of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the hippocampus. Rats were randomly assigned to three groups: the control group; the social isolation group; the social isolation plus exercise (SIE) group. Social isolation conditions, with or without exercise were maintained for 90d, and then multiple behavioral tests, including the open-field test, elevated plus maze test, and Morris water maze (MWM) test were administered. Following behavioral assessment, hippocampal tissue samples were obtained for measurement of BDNF and NGF. There wasn't a significant difference in locomotor activity between the groups (P>0.05). Anxiety scores were higher in the socially isolated group (P<0.05) than in the SIE group (P<0.05). According to the probe trial session of the MWM test results, exercise training improved platform crossings' number in the socially isolated rats (P<0.05). Exercise training ameliorated social isolation-induced reduction in hippocampal BDNF and NGF content (P<0.05). These findings suggest that exercise training improves cognitive functions via increasing hippocampal BDNF and NGF concentrations in socially isolated post-weaning rats.

It takes biking to learn: Physical activity improves learning a second language

Recent studies have shown that concurrent physical activity enhances learning a completely unfamiliar L2 vocabulary as compared to learning it in a static condition. In this paper we report a study whose aim is twofold: to test for possible positive effects of physical activity when L2 learning has already reached some level of proficiency, and to test whether the assumed better performance when engaged in physical activity is limited to the linguistic level probed at training (i.e. L2 vocabulary tested by means of a Word-Picture Verification task), or whether it extends also to the sentence level (which was tested by means of a Sentence Semantic Judgment Task). The results show that Chinese speakers with basic knowledge of English benefited from physical activity while learning a set of new words. Furthermore, their better performance emerged also at the sentential level, as shown by their performance in a Semantic Judgment task. Finally, an interesting temporal asymmetry between the lexical and the sentential level emerges, with the difference between the experimental and control group emerging from the 1^st testing session at the lexical level but after several weeks at the sentential level.

Running wheel training does not change neurogenesis levels or alter working memory tasks in adult rats

BACKGROUND

Exercise can change cellular structure and connectivity (neurogenesis or synaptogenesis), causing alterations in both behavior and working memory. The aim of this study was to evaluate the effect of exercise on working memory and hippocampal neurogenesis in adult male Wistar rats using a T-maze test.

METHODS

An experimental design with two groups was developed: the experimental group (n = 12) was subject to a forced exercise program for five days, whereas the control group (n = 9) stayed in the home cage. Six to eight weeks after training, the rats' working memory was evaluated in a T-maze test and four choice days were analyzed, taking into account alternation as a working memory indicator. Hippocampal neurogenesis was evaluated by means of immunohistochemistry of BrdU positive cells.

RESULTS

No differences between groups were found in the behavioral variables (alternation, preference index, time of response, time of trial or feeding), or in the levels of BrdU positive cells.

DISCUSSION

Results suggest that although exercise may have effects on brain structure, a construct such as working memory may require more complex changes in networks or connections to demonstrate a change at behavioral level.

Physical Activity Modulates Common Neuroplasticity Substrates in Major Depressive and Bipolar Disorder

Mood disorders (MDs) are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility, a need remains to better understand the interrelated mechanisms that contribute to neuroplasticity deficits in MDs and the means by which various therapeutics mitigate them. Of those therapeutics being investigated, physical activity (PA) has shown clear and consistent promise. Accordingly, the aims of this review are to (1) explicate key modulators, processes, and interactions that impinge upon multiple susceptibility points to effectuate neuroplasticity deficits in MDs; (2) explore the putative mechanisms by which PA mitigates these features; (3) review protocols used to induce the positive effects of PA in MDs; and (4) highlight implications for clinicians and researchers.

Physical Exercise Restores the Generation of Newborn Neurons in an Animal Model of Chronic Epilepsy

Neurogenesis impairment is associated with the chronic phase of the epilepsy in humans and also observed in animal models. Recent studies with animal models have shown that physical exercise is capable of improving neurogenesis in adult subjects, alleviating cognitive impairment and depression. Here, we show that there is a reduction in the generation of newborn granule cells in the dentate gyrus of adult rats subjected to a chronic model of epilepsy during the postnatal period of brain development. We also show that the physical exercise was capable to restore the number of newborn granule cells in this animals to the level observed in the control group. Notably, a larger number of newborn granule cells exhibiting morphological characteristics indicative of correct targeting into the hippocampal circuitry and the absence of basal dendrite projections was also observed in the epileptic animals subjected to physical exercise compared to the epileptic animals. The results described here could represent a positive interference of the physical exercise on the neurogenesis process in subjects with chronic epilepsy. The results may also help to reinterpret the benefits of the physical exercise in alleviating symptoms of depression and cognitive dysfunction.

Intense Exercise Promotes Adult Hippocampal Neurogenesis But Not Spatial Discrimination

Hippocampal neurogenesis persists throughout adult life and plays an important role in learning and memory. Although the influence of physical exercise on neurogenesis has been intensively studied, there is controversy in regard to how the impact of exercise may vary with its regime. Less is known about how distinct exercise paradigms may differentially affect the learning behavior. Here we found that, chronic moderate treadmill running led to an increase of cell proliferation, survival, neuronal differentiation, and migration. In contrast, intense running only promoted neuronal differentiation and migration, which was accompanied with lower expressions of vascular endothelial growth factor, brain-derived neurotrophic factor, insulin-like growth factor 1, and erythropoietin. In addition, the intensely but not mildly exercised animals exhibited a lower mitochondrial activity in the dentate gyrus. Correspondingly, neurogenesis induced by moderate but not intense exercise was sufficient to improve the animal’s ability in spatial pattern separation. Our data indicate that the effect of exercise on spatial learning is intensity-dependent and may involve mechanisms other than a simple increase in the number of new neurons.