Environmental enrichment in adulthood eliminates neuronal death in experimental Parkinsonism

Considering the response in addition to the challenge - a narrative review in appraisal of a motor reserve framework

The remarkable increase in human life expectancy over the past century has been achieved at the expense of the risk of age-related impairment and disease. Neurodegeneration, be it part of normal aging or due to neurodegenerative disorders, is characterized by loss of specific neuronal populations, leading to increasing clinical impairment. The individual course may be described as balance between aging- or disease-related pathology and intrinsic mechanisms of adaptation. There is plenty of evidence that the human brain is provided with exhaustible resources to maintain function in the face of adverse conditions. While a reserve concept has mainly been coined in cognitive neuroscience, emerging evidence suggests similar mechanisms to underlie individual differences of adaptive capacity within the motor system. In this narrative review, we summarize what has been proposed to date about a motor reserve (mR) framework. We present current evidence from research in aging subjects and people with neurological conditions, followed by a description of what is known about potential neuronal substrates of mR so far. As there is no gold standard of mR quantification, we outline current approaches which describe various indicators of mR. We conclude by sketching out potential future directions of research. Expediting our understanding of differences in individual motor resilience towards aging and disease will eventually contribute to new, individually tailored therapeutic strategies. Provided early diagnosis, enhancing the individual mR may be suited to postpone disease onset by years and may be an efficacious contribution towards healthy aging, with an increased quality of life for the elderly.

Reduction of restricted repetitive behavior by environmental enrichment: Potential neurobiological mechanisms

Restricted repetitive behaviors (RRB) are one of two diagnostic criteria for autism spectrum disorder and common in other neurodevelopmental and psychiatric disorders. The term restricted repetitive behavior refers to a wide variety of inflexible patterns of behavior including stereotypy, self-injury, restricted interests, insistence on sameness, and ritualistic and compulsive behavior. However, despite their prevalence in clinical populations, their underlying causes remain poorly understood hampering the development of effective treatments. Intriguingly, numerous animal studies have demonstrated that these behaviors are reduced by rearing in enriched environments (EE). Understanding the processes responsible for the attenuation of repetitive behaviors by EE should offer insights into potential therapeutic approaches, as well as shed light on the underlying neurobiology of repetitive behaviors. This review summarizes the current knowledge of the relationship between EE and RRB and discusses potential mechanisms for EE's attenuation of RRB based on the broader EE literature. Existing gaps in the literature and future directions are also discussed.

Neuroanatomical and neurochemical effects of prolonged social isolation in adult mice

Introduction

As social animals, our health depends in part on interactions with other human beings. Yet millions suffer from chronic social isolation, including those in nursing/assisted living facilities, people experiencing chronic loneliness as well as those in enforced isolation within our criminal justice system. While many historical studies have examined the effects of early isolation on the brain, few have examined its effects when this condition begins in adulthood. Here, we developed a model of adult isolation using mice (C57BL/6J) born and raised in an enriched environment.

Methods

From birth until 4 months of age C57BL/6J mice were raised in an enriched environment and then maintained in that environment or moved to social isolation for 1 or 3 months. We then examined neuronal structure and catecholamine and brain derived neurotrophic factor (BDNF) levels from different regions of the brain, comparing animals from social isolation to enriched environment controls.

Results

We found significant changes in neuronal volume, dendritic length, neuronal complexity, and spine density that were dependent on brain region, sex, and duration of the isolation. Isolation also altered dopamine in the striatum and serotonin levels in the forebrain in a sex-dependent manner, and also reduced levels of BDNF in the motor cortex and hippocampus of male but not female mice.

Conclusion

These studies show that isolation that begins in adulthood imparts a significant change on the homeostasis of brain structure and chemistry.

MSK1 is required for the beneficial synaptic and cognitive effects of enriched experience across the lifespan

Positive experiences, such as social interaction, cognitive training and physical exercise, have been shown to ameliorate some of the harms to cognition associated with ageing. Animal models of positive interventions, commonly known as environmental enrichment, strongly influence neuronal morphology and synaptic function and enhance cognitive performance. While the profound structural and functional benefits of enrichment have been appreciated for decades, little is known as to how the environment influences neurons to respond and adapt to these positive sensory experiences. We show that adult and aged male wild-type mice that underwent a 10-week environmental enrichment protocol demonstrated improved performance in a variety of behavioural tasks, including those testing spatial working and spatial reference memory, and an enhancement in hippocampal LTP. Aged animals in particular benefitted from enrichment, performing spatial memory tasks at levels similar to healthy adult mice. Many of these benefits, including in gene expression, were absent in mice with a mutation in an enzyme, MSK1, which is activated by BDNF, a growth factor implicated in rodent and human cognition. We conclude that enrichment is beneficial across the lifespan and that MSK1 is required for the full extent of these experience-induced improvements of cognitive abilities, synaptic plasticity and gene expression.

Molecular mechanisms underlying the neuroprotection of environmental enrichment in Parkinson's disease

Parkinson's disease is the most common movement disorder, affecting about 1% of the population over the age of 60 years. Parkinson's disease is characterized clinically by resting tremor, bradykinesia, rigidity and postural instability, as a result of the progressive loss of nigrostriatal dopaminergic neurons. In addition to this neuronal cell loss, Parkinson's disease is characterized by the accumulation of intracellular protein aggregates, Lewy bodies and Lewy neurites, composed primarily of the protein α-synuclein. Although it was first described almost 200 years ago, there are no disease-modifying drugs to treat patients with Parkinson's disease. In addition to conventional therapies, non-pharmacological treatment strategies are under investigation in patients and animal models of neurodegenerative disorders. Among such strategies, environmental enrichment, comprising physical exercise, cognitive stimulus, and social interactions, has been assessed in preclinical models of Parkinson's disease. Environmental enrichment can cause structural and functional changes in the brain and promote neurogenesis and dendritic growth by modifying gene expression, enhancing the expression of neurotrophic factors and modulating neurotransmission. In this review article, we focus on the current knowledge about the molecular mechanisms underlying environmental enrichment neuroprotection in Parkinson's disease, highlighting its influence on the dopaminergic, cholinergic, glutamatergic and GABAergic systems, as well as the involvement of neurotrophic factors. We describe experimental pre-clinical data showing how environmental enrichment can act as a modulator in a neurochemical and behavioral context in different animal models of Parkinson's disease, highlighting the potential of environmental enrichment as an additional strategy in the management and prevention of this complex disease.

Efficacy of invasive and non-invasive methods for the treatment of Parkinson's disease: Nanodelivery and enriched environment

Parkinson's disease (PD) is the second most common neurodegenerative disorder characterised by the loss of dopaminergic neurons in the substantia nigra pars compacta and the subsequent motor disability. The most frequently used treatments in clinics, such as L-DOPA, restore dopaminergic neurotransmission in the brain. However, these treatments are only symptomatic, have temporary efficacy, and produce side effects. Part of the side effects are related to the route of administration as the consumption of oral tablets leads to unspecific pulsatile activation of dopaminergic receptors. For this reason, it is necessary to not only find alternative treatments, but also to develop new administration systems with better security profiles. Nanoparticle delivery systems are new administration forms designed to reach the pharmacological target in a highly specific way, leading to better drug bioavailability, efficacy and safety. Some of these delivery systems have shown promising results in animal models of PD not only when dopaminergic drugs are administered, but even more when neurotrophic factors are released. These latter compounds promote maturation and survival of dopaminergic neurons and can be exogenously administered in the form of pharmacological therapy or endogenously generated by non-pharmacological methods. In this sense, experimental exposure to enriched environments, a non-invasive strategy based on the combination of social and inanimate stimuli, enhances the production of neurotrophic factors and produces a neuroprotective effect in parkinsonian animals. In this review, we will discuss new nanodelivery systems in PD with a special focus on therapies that increase the release of neurotrophic factors.

Enriched environment as a nonpharmacological neuroprotective strategy

The structure and functions of the central nervous system are influenced by environmental stimuli, which also play an important role in brain diseases. Enriched environment (EE) consists of producing modifications in the environment of standard laboratory animals to induce an improvement in their biological conditions. This paradigm promotes transcriptional and translational effects that result in ameliorated motor, sensory, and cognitive stimulation. EE has been shown to enhance experience-dependent cellular plasticity and cognitive performance in animals housed under these conditions compared with animals housed under standard conditions. In addition, several studies claim that EE induces nerve repair by restoring functional activities through morphological, cellular, and molecular adaptations in the brain that have clinical relevance in neurological and psychiatric disorders. In fact, the effects of EE have been studied in different animal models of psychiatric and neurological diseases, such as Alzheimer's disease, Parkinson's disease, schizophrenia, ischemic brain injury, or traumatic brain injury, delaying the onset and progression of a wide variety of symptoms of these disorders. In this review, we analyze the action of EE focused on diseases of the central nervous system and the translation to humans to develop a bridge to its application.

Enriched environment can reverse chronic sleep deprivation-induced damage to cellular plasticity in the dentate gyrus of the hippocampus

Objective

We studied whether enriched environment (EE), a classic epigenetics paradigm, can prevent cellular plasticity damage caused by chronic sleep deprivation (SD).

Methods

We performed SD in mice by a modified multi-platform method (MMPM). Mice in the SD group were deprived of sleep for 18 h a day. In addition, half of the mice in the chronic SD group were exposed to EE stimuli for 6 h per day. Immunostaining analyzed neurogenesis and neural progenitor cell-differentiated phenotypes in the hippocampal dentate gyrus (DG) region.

Result

At 13 weeks, compared with the control group, SD severely impaired the proliferation and differentiation of neural stem cells, and EE completely reversed the process. SD can induce gliosis in the mouse hippocampus, and EE can delay the process.

Conclusion:

Our results suggest that chronic SD may damage the neurogenesis in the DG of the hippocampus. However, enrichment stimulation can reverse the processing by promoting neuronal repair related to neuronal plasticity.

A systematic review and meta-analysis on effects of aerobic exercise in people with Parkinson's disease

Previous studies have shown that aerobic exercise is an effective way to improve symptoms of Parkinson's disease (PD). The aim of this study [PROSPERO CRD42022340730] was to explore the effects of aerobic exercises on balance, gait, motor function, and quality of life in PD patients. Searches were performed in PubMed, Web of Science, and EBSCO electronic databases. The Cochrane risk assessment tool was used to evaluate the methodological quality of the included literature. From 1287 search records initially identified, 20 studies were considered eligible for systematic review and meta-analysis. There was a significant effect of aerobic exercise on improving timed up and go test [standardized mean difference (SMD), -0.41 (95% CI, -0.61 to -0.22), p < 0.00001], Berg Balance Scale [0.99 (95% CI, 0.76 to 1.23), p < 0.00001], stride/step length [0.32 (95% CI, 0.03 to 0.61), p = 0.03], gait velocity [0.49 (95% CI, 0.20 to 0.78), p = 0.0009], Unified Parkinson's Disease Rating Scale Part-III [-0.40 (95% CI, -0.55 to -0.24), p < 0.00001], and 6-minute walking test [0.35 (95% CI, 0.13 to 0.56), p = 0.002] in people with PD, but not in step cadence [-0.08 (95% CI, -0.43 to 0.27), p = 0.65] and Parkinson's Disease Questionnaire-39 [-0.113 (95% CI, -0.39 to 0.13), p = 0.32]. Aerobic exercise had beneficial effects in improving balance, gait (velocity and stride/step length), and motor function in PD patients. However, aerobic exercise had no significant associations with the step cadence and quality of life in PD patients.

Beneficial effects and neurobiological aspects of environmental enrichment associated to major depressive disorder and autism spectrum disorder

A suitable enriched environment favors development but can also influence behavior and neuronal circuits throughout development. Studies have shown that environmental enrichment (EE) can be used as an essential tool or combined with conventional treatments to improve psychiatric and neurological symptoms, including major depressive disorder (MDD) and autism spectrum disorder (ASD). Both disorders affect a significant percentage of the world's population and have complex pathophysiology. Moreover, the available treatments for MDD and ASD are still inadequate for many affected individuals. Experimental models demonstrate that EE has significant positive effects on behavioral modulation. In addition, EE has effects on neurobiology, including improvement in synaptic connections and neuroplasticity, modulation of neurotransmissions, a decrease in inflammation and oxidative stress, and other neurobiology effects that can be involved in the pathophysiology of MDD and ASD. Thus, this review aims to describe the leading behavioral and neurobiological effects associated with EE in MDD and ASD.

Exercise duration differentially effects age-related neuroinflammation and hippocampal neurogenesis

The physiological effects of exercise vary as a function of frequency and length. However, research on the duration-dependent effects of exercise has focused primarily on young adults and less is known about the influence of exercise duration in the aged. The current study compared the effects of short-term and long-term running wheel access on hippocampal neurogenesis and neuroimmune markers in aged (19-23 months) male C57BL/6J mice. Aged mice were given 24-hour access to a running wheel for 14 days (short-term) or 51 days (long-term). Groups of non-running aged and young (5 months) mice served as comparison groups to detect age-related differences and effects of exercise. Long-term, but not short-term, exercise increased hippocampal neurogenesis as assessed by number of doublecortin (DCX) positive cells in the granular cell layer. Assessment of cytokines, receptors, and glial-activation markers showed the expected age-related increase compared to young controls. In the aged, exercise as a function of duration regulated select aspects of the neuroimmune profile. For instance, hippocampal expression of interleukin (IL)-10 was increased only following long-term exercise. While in contrast brain levels of IL-6 were reduced by both short- and long-term exercise. Additional findings showed that exercise does not modulate all aspects of age-related neuroinflammation and/or may have differential effects in hippocampal compared to brain samples. Overall, the data indicate that increasing exercise duration produces more robust effects on immune modulation and hippocampal neurogenesis.

Inhibition of Nigral Microglial Activation Reduces Age-Related Loss of Dopaminergic Neurons and Motor Deficits

Parkinson's disease (PD) is an age-related neurodegenerative disease caused by a selective loss of dopaminergic (DA) neurons in the substantia nigra (SN). Microglial activation is implicated in the pathogenesis of PD. This study aimed to characterize the role of microglial activation in aging-related nigral DA neuron loss and motor deficits in mice. We showed that, compared to 3-month-old mice, the number of DA neurons in the SN and the expression of dopamine transporter (DAT) in the striatum decreased during the period of 9 to 12 months of age. Motor deficits and microglial activation in the SN were also evident during these months. The number of DA neurons was negatively correlated with the degrees of microglial activation. The inhibition of age-related microglial activation by ibuprofen during these 3 months decreased DA neuron loss in the SN. Eliminating the microglia prevented systemic inflammation-induced DA neuron death. Forcing mice to run during these 3 months inhibited microglial activation and DA neuron loss. Blocking the brain-derived neurotrophic factor (BDNF) signaling eliminated the exercise-induced protective effects. In conclusion, nigral DA neurons were susceptible to local microglial activation. Running exercise upregulated BDNF-TrkB signaling and inhibited microglial activation during aging. Long-term exercise can be considered as a non-pharmacological strategy to ameliorate microglial activation and related neurodegeneration.

Environmental Enrichment Effects on the Brain-Derived Neurotrophic Factor Expression in Healthy Condition, Alzheimer's Disease, and Other Neurodegenerative Disorders

Brain-derived neurotrophic factor (BDNF), a protein belonging to the neurotrophin family, is known to be heavily involved in synaptic plasticity processes that support brain development, post-lesion regeneration, and cognitive performances, such as learning and memory. Evidence indicates that BDNF expression can be epigenetically regulated by environmental stimuli and thus can mediate the experience-dependent brain plasticity. Environmental enrichment (EE), an experimental paradigm based on the exposure to complex stimulations, constitutes an efficient means to investigate the effects of high-level experience on behavior, cognitive processes, and neurobiological correlates, as the BDNF expression. In fact, BDNF exerts a key role in mediating and promoting EE-induced plastic changes and functional improvements in healthy and pathological conditions. This review is specifically aimed at providing an updated framework of the available evidence on the EE effects on brain and serum BDNF levels, by taking into account both changes in protein expression and regulation of gene expression. A further purpose of the present review is analyzing the potential of BDNF regulation in coping with neurodegenerative processes characterizing Alzheimer's disease (AD), given BDNF expression alterations are described in AD patients. Moreover, attention is also paid to EE effects on BDNF expression in other neurodegenerative disease. To investigate such a topic, evidence provided by experimental studies is considered. A deeper understanding of environmental ability in modulating BDNF expression in the brain may be fundamental in designing more tuned and effective applications of complex environmental stimulations as managing approaches to AD.

Unwanted Exacerbation of the Immune Response in Neurodegenerative Disease: A Time to Review the Impact

The COVID-19 pandemic imposed a series of behavioral changes that resulted in increased social isolation and a more sedentary life for many across all age groups, but, above all, for the elderly population who are the most vulnerable to infections and chronic neurodegenerative diseases. Systemic inflammatory responses are known to accelerate neurodegenerative disease progression, which leads to permanent damage, loss of brain function, and the loss of autonomy for many aged people. During the COVID-19 pandemic, a spectrum of inflammatory responses was generated in affected individuals, and it is expected that the elderly patients with chronic neurodegenerative diseases who survived SARSCoV-2 infection, it will be found, sooner or later, that there is a worsening of their neurodegenerative conditions. Using mouse prion disease as a model for chronic neurodegeneration, we review the effects of social isolation, sedentary living, and viral infection on the disease progression with a focus on sickness behavior and on the responses of microglia and astrocytes. Focusing on aging, we discuss the cellular and molecular mechanisms related to immunosenescence in chronic neurodegenerative diseases and how infections may accelerate their progression.

The Effects of Sensory Enrichment After a Laboratory Stressor on Human Skin Barrier Recovery in a Randomized Trial

OBJECTIVE

Environmental enrichment (EE) can reduce stress, alter immunity, and speed wound healing in animals. However, it is not known whether these effects translate to humans. This study aimed to investigate whether sensory EE could improve wound healing after a stressor in humans.

METHODS

A total of 105 participants underwent a tape-stripping procedure and were then stressed using a laboratory stress paradigm. After this, they were randomized to interact for 30 minutes with one of two possible sensory EE interventions (music as auditory enrichment or a Paro robot as multisensory enrichment) or to a control condition. Skin barrier recovery was measured using transepidermal water loss at baseline, after the stressor, and after the intervention. Stress was measured using self-report, heart rate, blood pressure, and salivary stress-related biological measures. Enjoyment during the intervention was measured by self-report as a possible mediator.

RESULTS

The Paro condition had significantly improved skin barrier recovery (mean [M] = 44%, standard error [SE] = 1.92) compared with the control condition (M = 37% SE = 2.01, F(2,88) = 3.25, p = .043), both with and without controlling for covariates. The music condition did not significantly differ from the other conditions (M = 42%, SE = 1.95, p values > .05). Both objective and subjective stress measures did not significantly differ between conditions. Mediational analysis showed that enjoyment levels during the intervention period significantly mediated the relationship between condition and skin barrier recovery (z = 2.00, p = .046).

CONCLUSIONS

Paro, or other companion robots, may be an effective form of enrichment to improve skin barrier recovery in humans after a laboratory stressor, and this effect may be due to enjoyment. Further research with patient groups is required to investigate whether Paro can help heal clinical wounds.

TRIAL REGISTRATION

ACTRN12618000953235, registered at https://anzctr.org.au.

Short-Term Environmental Enrichment is a Stronger Modulator of Brain Glial Cells and Cervical Lymph Node T Cell Subtypes than Exercise or Combined Exercise and Enrichment

Physical exercise (PE) and environmental enrichment (EE) can modulate immunity. However, the differential effects of short-term PE, EE, and PE + EE on neuroimmune mechanisms during normal aging has not been elucidated. Hence, a cohort of 3-, 8-, and 13-month-old immunologically unchallenged C57BL/6 wild-type mice were randomly assigned to either Control, PE, EE, or PE + EE groups and provided with either no treatment, a running wheel, a variety of plastic and wooden objects alone or in combination with a running wheel for seven weeks, respectively. Immunohistochemistry and 8-color flow cytometry were used to determine the numbers of dentate gyrus glial cells, and the proportions of CD4+ and CD8+ T cell numbers and their subsets from cervical lymph nodes, respectively. An increase in the number of IBA1+ microglia in the dentate gyrus at 5 and 10 months was observed after EE, while PE and PE + EE increased it only at 10 months. No change in astroglia number in comparison to controls were observed in any of the treatment groups. Also, all treatments induced significant differences in the proportion of specific T cell subsets, i.e., CD4+ and CD8+ T naïve (TN), central memory (TCM), and effector memory (TEM) cells. Our results suggest that in the short-term, EE is a stronger modulator of microglial and peripheral T cell subset numbers than PE and PE + EE, and the combination of short-term PE and EE has no additive effects.

Reduced Interaction of Aggregated α-Synuclein and VAMP2 by Environmental Enrichment Alleviates Hyperactivity and Anxiety in a Model of Parkinson's Disease

Parkinson’s disease (PD) is a prevalent motor disease caused by the accumulation of mutated α-synuclein (α-Syn); however, its early stages are also characterized by non-motor symptoms, such as olfactory loss, cognitive decline, depression, and anxiety. The therapeutic effects of environmental enrichment (EE) on motor recovery have been reported, but its effects on non-motor symptoms remain unclear. Herein, we reveal the beneficial effects of EE on PD-related non-motor symptoms and changes in synaptic plasticity in the nucleus accumbens. To investigate its therapeutic effects in the early phase of PD, we randomly assigned eight-month-old mice overexpressing human A53T (hA53T) α-Syn to either the EE or standard condition groups for two months. Next, we performed behavioral tests and biochemical and histological analyses at 10 months of age. EE significantly alleviated locomotor hyperactivity and anxiety during the early stages of PD. It normalized the levels of tyrosine hydroxylase, phosphorylated and oligomeric α-Syn, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex-forming proteins, including synaptosomal-associated protein, 25 kDa, syntaxin1, and vesicle-associated membrane protein 2 (VAMP2). Moreover, the interactions between VAMP2 and pSer129 α-Syn were markedly reduced following EE. The restoration of synaptic vesicle transportation status may underlie the neuroprotective effects of EE in hA53T α-Syn mice.

A Mobile App Specifically Designed to Facilitate Exercise in Parkinson Disease: Single-Cohort Pilot Study on Feasibility, Safety, and Signal of Efficacy

Background

Many people with Parkinson disease do not have access to exercise programs that are specifically tailored to their needs and capabilities. This mobile app allows people with Parkinson disease to access Parkinson disease–specific exercises that are individually tailored using in-app demographic questions and performance tests which are fed into an algorithm which in turn produces a video-guided exercise program.

Objective

To test the feasibility, safety, and signal of efficacy of a mobile app that facilitates exercise for people with Parkinson disease.

Methods

A prospective, single-cohort design of people with Parkinson disease who had downloaded the 9zest app for exercise was used for this 12-week pilot study. Participants, who were recruited online, were encouraged to exercise with the full automated app for ≥150 minutes each week. The primary endpoints were feasibility (app usage and usability questions) and safety (adverse events and falls). The primary endpoints for signal of efficacy were a comparison of the in-app baseline and 8-week outcomes on the 30-second Sit-To-Stand (STS) test, Timed Up and Go (TUG) test, and the Parkinson’s Disease Questionnaire 8 (PDQ8).

Results

For feasibility, of the 28 participants that completed the study, 12 participants averaged >150 minutes of app usage per week (3 averaged 120-150, 4 averaged 90-120, and 9 averaged less than 90 minutes). A majority of participants (>74%) felt the exercise was of value (16/19; 9 nonrespondents), provided adequate instruction (14/19; 9 nonrespondents), and was appropriate for level of function (16/19; 9 nonrespondents). For safety, there were no serious adverse events that occurred during the app-guided exercise. There were 4 reports of strain/sprain injuries while using the app among 3 participants, none of which necessitated medical attention. For signal of efficacy, there was improvement for each of the primary endpoints: STS (P=.01), TUG (P<.001), and PDQ8 (P=.01).

Conclusions

Independent, video-guided exercise using a mobile app designed for exercise in Parkinson disease was safe and feasible though there was variability in app usage. Despite this, the results provide evidence for a signal of efficacy as there were improvements in 3 of the 3 outcomes.

Trial Registration

ClinicalTrials.gov NCT03459586; https://clinicaltrials.gov/ct2/show/NCT03459586

Current Perspectives on Aerobic Exercise in People with Parkinson's Disease

Parkinson's disease (PD) is a progressive neurological disorder characterized by motor and non-motor symptoms for which only symptomatic treatments exist. Exercise is a widely studied complementary treatment option. Aerobic exercise, defined as continuous movement of the body's large muscles in a rhythmic manner for a sustained period that increases caloric requirements and aims at maintaining or improving physical fitness, appears promising. We performed both a scoping review and a systematic review on the generic and disease-specific health benefits of aerobic exercise for people with PD. We support this by a meta-analysis on the effects on physical fitness (VO2max), motor symptoms (Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor section), and health-related quality of life (39-item Parkinson's disease Questionnaire (PDQ-39)). Aerobic exercise has generic health benefits for people with PD, including a reduced incidence of cardiovascular disease, a lower mortality, and an improved bone health. Additionally, there is level 1 evidence that aerobic exercise improves physical fitness (VO2max) and attenuates motor symptoms (MDS-UPDRS motor section) in the off-medication state, although the long-term effects (beyond 6 months) remain unclear. Dosing the exercise matters: improvements appear to be greater after training at higher intensities compared with moderate intensities. We found insufficient evidence for a beneficial effect of aerobic exercise on health-related quality of life (PDQ-39) and conflicting results regarding non-motor symptoms. Compliance to exercise regimes is challenging for PD patients but may be improved by adding exergaming elements to the training program. Aerobic exercise seems a safe intervention for people with PD, although care must be taken to avoid falls in at-risk individuals. Further studies are needed to establish the long term of aerobic exercise, including a focus on non-motor symptoms and health-related quality of life.

GDNF and GFRα1 Are Required for Proper Integration of Adult-Born Hippocampal Neurons

The glial cell line-derived neurotrophic factor (GDNF) is required for the survival and differentiation of diverse neuronal populations during nervous system development. Despite the high expression of GDNF and its receptor GFRα1 in the adult hippocampus, the functional role of this system remains unknown. Here, we show that GDNF, acting through its GFRα1 receptor, controls dendritic structure and spine density of adult-born granule cells, which reveals that GFRα1 is required for their integration into preexisting circuits. Moreover, conditional mutant mice for GFRα1 show deficits in behavioral pattern separation, a task in which adult neurogenesis is known to play a critical role. We also find that running increases GDNF in the dentate gyrus and promotes GFRα1-dependent CREB (cAMP response element-binding protein) activation and dendrite maturation. Together, these findings indicate that GDNF/GFRα1 signaling plays an essential role in the plasticity of adult circuits, controlling the integration of newly generated neurons.

The Relevance of Operant Behavior in Conceptualizing the Psychological Well-Being of Captive Animals

The term "psychological well-being" is used in reference to husbandry with animals in human care settings such as research, agriculture, and zoos. This article seeks to clarify and conceptualize the term based upon two approaches that draw from several bodies of literature: the experimental analysis of behavior, experimental psychology, animal welfare and husbandry, farm animal behavior, zoo husbandry, and ethology. One approach focuses on the presence of problem behavior such as stereotypies, depressive-like behavior, and aggression, and emphasizes the conditions under which aberrant behavior in animals under human care occurs. The second approach examines what might be considered wellness by emphasizing opportunities to engage with its environment, or the absence of such opportunities, even if problematic behavior is not exhibited. Here, access to an interactive environment is relatively limited so opportunities for operant (voluntary) behavior could be considered. Designing for operant behavior provides opportunities for variability in both behavior and outcomes. Operant behavior also provides control over the environment, a characteristic that has been a core assumption of well-being. The importance of interactions with one's environment is especially evident in observations that animals prefer opportunities to work for items necessary for sustenance, such as food, over having them delivered freely. These considerations raise the importance of operant behavior to psychological well-being, especially as benefits to animals under human care.

Improvements to Healthspan Through Environmental Enrichment and Lifestyle Interventions: Where Are We Now?

Environmental enrichment (EE) is an experimental paradigm that is used to explore how a complex, stimulating environment can impact overall health. In laboratory animal experiments, EE housing conditions typically include larger-than-standard cages, abundant bedding, running wheels, mazes, toys, and shelters which are rearranged regularly to further increase stimulation. EE has been shown to improve multiple aspects of health, including but not limited to metabolism, learning and cognition, anxiety and depression, and immunocompetence. Recent advances in lifespan have led some researchers to consider aging as a risk factor for disease. As such, there is a pressing need to understand the processes by which healthspan can be increased. The natural and predictable changes during aging can be reversed or decreased through EE and its underlying mechanisms. Here, we review the use of EE in laboratory animals to understand mechanisms involved in aging, and comment on relative areas of strength and weakness in the current literature. We additionally address current efforts toward applying EE-like lifestyle interventions to human health to extend healthspan. Although increasing lifespan is a clear goal of medical research, improving the quality of this added time also deserves significant attention. Despite hurdles in translating experimental results toward clinical application, we argue there is great potential in using features of EE toward improving human healthy life expectancy or healthspan, especially in the context of increased global longevity.

Effects of Exercise and Ferulic Acid on Alpha Synuclein and Neuroprotective Heat Shock Protein 70 in An Experimental Model of Parkinsonism Disease

BACKGROUND & OBJECTIVE

This study investigated the effects of ferulic acid (FR), muscle exercise (Ex) and combination of them on rotenone (Rot)-induced Parkinson disease (PD) in mice as well as their underlying mechanisms.

METHOD

56 male C57BL/6 mice were allocated into 8 equal groups, 1) Normal control (CTL), 2) FR (mice received FR at 20 mg/kg/day), 3) Ex (mice received swimming Ex) and 4) Ex + FR (mice received FR and Ex), 5) Rot (mice received Rot 3 mg/Kg i.p. for 70 days), 6) ROT+ FR (mice received Rot + FR at 20 mg/kg/day), 7) ROT+ Ex (mice received Rot + swimming Ex) and 8) ROT+ Ex + FR (mice received Rot + FR and Ex). ROT group showed significant impairment in motor performance and significant reduction in tyrosine hydroxylase (TH) density and Hsp70 expression (p< 0.05) with Lewy bodies (alpha synuclein) aggregates in corpus striatum. Also, ROT+FR, ROT+EX and ROT + Ex+ FR groups showed significant improvement in behavioral and biochemical changes, however the effect of FR alone was more potent than Ex alone (p< 0.05) and addition of Ex to FR caused no more significant improvement than FR alone.

CONCLUSION

We concluded that, FR and Ex improved the motor performance in rotenone-induced PD rodent model which might be due to increased Hsp70 expression and TH density in corpus striatum and combination of both did not offer more protection than FR alone.

Duration of Environmental Enrichment Determines Astrocyte Number and Cervical Lymph Node T Lymphocyte Proportions but Not the Microglial Number in Middle-Aged C57BL/6 Mice

Environmental enrichment (EE) has been shown to modulate behavior and immunity. We recently reported that both short and long-term EE enhance baseline locomotion and alleviate depressive-like behavior, but only long-term EE affects locomotion adversely in a threatening environment and enhances anxiety-like behavior in middle-age mice. We have now investigated whether the observed changes in behavior after short- and long-term EE were associated with underlying immune changes. Hence, at the end of behavioral testing, mice were sacrificed, and brains and cervical lymph nodes were collected to investigate the differential effects of the duration of EE (short- and long-term) on the number of immunopositive glial cells in the dentate gyrus, CA1, CA2, and CA3 regions of the hippocampus and proportions of T cell subsets in the cervical lymph nodes using immunohistochemistry and flow cytometry, respectively. EE, regardless of duration, caused an increase in microglia number within the dentate gyrus, CA1 and CA3 hippocampal regions, but only long-term EE increased astrocytes number within the dentate gyrus and CA3 hippocampal regions. A significantly higher proportion of CD8⁺ naive T cells was observed after long-term EE vs. short-term EE. No significant differences were observed in the proportion of central memory and effector memory T cells or early activated CD25⁺ cells between any of the test groups. Our results suggest that EE, irrespective of duration, enhances the numbers of microglia, but long-term EE is required to modify astrocyte number and peripheral T cell proportions in middle-aged mice. Our findings provide new insights into the therapeutic effects of EE on various brain disorders, which may be at least partly mediated by glial and neuroimmune modulation.

Effects of aging on the motor, cognitive and affective behaviors, neuroimmune responses and hippocampal gene expression

The known effects of aging on the brain and behavior include impaired cognition, increases in anxiety and depressive-like behaviors, and reduced locomotor activity. Environmental exposures and interventions also influence brain functions during aging. We investigated the effects of normal aging under controlled environmental conditions and in the absence of external interventions on locomotor activity, cognition, anxiety and depressive-like behaviors, immune function and hippocampal gene expression in C57BL/6 mice. Healthy mice at 4, 9, and 14 months of age underwent behavioral testing using an established behavioral battery, followed by cellular and molecular analysis using flow cytometry, immunohistochemistry, and quantitative PCR. We found that 14-month-old mice showed significantly reduced baseline locomotion, increased anxiety, and impaired spatial memory compared to younger counterparts. However, no significant differences were observed for depressive-like behavior in the forced-swim test. Microglia numbers in the dentate gyrus, as well as CD8+ memory T cells increased towards late middle age. Aging processes exerted a significant effect on the expression of 43 genes of interest in the hippocampus. We conclude that aging is associated with specific changes in locomotor activity, cognition, anxiety-like behaviors, neuroimmune responses and hippocampal gene expression.

Exercise and Parkinson's Disease

Parkinson's disease (PD) is an aging-related neurodegenerative disorder characterized by progressive motor impairment.The etiology of PD is poorly understood but likely involves both genetic and environmental factors; the management of the disease is still with symptomatic therapy without any interference on the progression of neurodegeneration. In the past two decades, the results of a series of prospective cohort studies suggested that lifestyle factors likely modify the risk of developing PD. Among these, physical activity is known to reduce the risk of a wide range of diseases and conditions, including cardiovascular disease, stroke, and diabetes.Recently, a growing body of evidence has suggested that increased physical activity may also reduce the risk of PD and partly improve motor and non-motor symptoms during the disease course.Here we report the main findings on the effect of physical activity on both mobility and cognition either in animal models of PD or in people with PD. We also highlighted the structural and functional links between gait and cognition by reporting evidence from neuroimaging studies.

Examining the Reserve Hypothesis in Parkinson's Disease: A Longitudinal Study

BACKGROUND

Whether reserve plays a role in Parkinson's disease (PD) patients has received less attention than in dementia and has been mainly examined in relation with cognitive function.

OBJECTIVE

To investigate whether reserve plays a role in the severity and progression of motor, cognitive, and nonmotor PD symptoms by examining whether education level (proxy of reserve) is associated with baseline performance and rate of progression.

METHODS

We used data from a longitudinal cohort of PD patients (≤5-year disease duration at baseline) annually followed up to 5 years (n = 393; 41% women; mean age = 62.3 years, standard deviation = 10.0; mean disease duration = 2.6 years, standard deviation = 1.5). We examined the relationship of education with time to reach Hoehn and Yahr stage ≥3 using Cox regression and with baseline severity and progression of motor (Movement Disorder Society-Unified Parkinson's Disease Rating Scale parts II and III, gait speed), cognitive (Mini-Mental State Examination), and nonmotor (depression, anxiety, nonmotor symptoms scale, quality of life) symptoms using mixed models.

RESULTS

Education level was not associated with age at onset or diagnosis. Compared with the low-education group, the incidence of Hoehn and Yahr ≥3.0 was 0.42 times lower (95% confidence interval, 0.22-0.82, P = 0.012) in the high-education group. Higher education was associated with better baseline motor function (P < 0.001), but not with the rate of motor decline (P > 0.15). Similar results were observed for cognition. Education was not associated with nonmotor symptoms.

CONCLUSIONS

Higher education is associated with better baseline motor/cognitive function in PD, but not with rate of decline, and with a lower risk of reaching Hoehn and Yahr ≥3 during the follow-up. Our observations are consistent with a passive reserve hypothesis for motor/cognitive symptoms. © 2019 International Parkinson and Movement Disorder Society.

Pre-diagnosis physical activity habits are associated with age of diagnosis in Parkinson's disease

INTRODUCTION

Studies suggest that exercise may be neuroprotective when implemented before the clinical presentation of Parkinson's disease (PD). Levels of brain-derived neurotrophic factor (BDNF), theorized to play a role in neuroprotection, are affected by its genotype and exercise. Here we explore this previously unstudied interaction on age at diagnosis and severity of symptoms.

METHODS

76 participants with PD submitted buccal cells to determine BDNF genotype, completed the modified Lifetime Physical Activity Questionnaire to determine exercise habits, and were assessed using the Movement Disorder Society - Unified Parkinson's Disease Rating Scale III (MDS-UPDRS-III) and the Mini-Balance Evaluations Test (MBT). For aim 1 (age at diagnosis), 60 participants (age = 69.6 ± 7.4; males = 45, females = 15) were analyzed. For aim 2 (severity of symptoms), 54 participants (age = 70.0 ± 7.6; males = 41, females = 13) were analyzed.

RESULTS

The final hierarchical regression model for age at diagnosis produced an R2 = 0.146, p = .033; however, the only significant variable in the final model was average moderate physical activity from ages 20s to 40s (p = .009). The regression for MDS-UPDRS III was not significant; however, the regression for MBT was, p = .0499. In the final model, 23.1% of the variance was explained. Years since diagnosis (p = .014) and average vigorous physical activity from ages 20s to 40s (p = .047) were the only predictors in the final model.

CONCLUSIONS

While a strong interaction between BDNF genotype and lifetime physical activity was not observed, our results suggest that lifetime exercise may be neuroprotective in PD. Specifically, higher amounts of moderate PA were associated with an older age at diagnosis.

Diosgenin Attenuates Lipopolysaccharide-Induced Parkinson's Disease by Inhibiting the TLR/NF-κB Pathway

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disease characterized by loss of dopaminergic neurons in the substantia nigra. Diosgenin is a natural steroid saponin which was shown to play a beneficial role in Alzheimer's disease.

OBJECTIVE

This study sought to investigate the potential effect of diosgenin on a rat model of PD.

METHODS

Sprague Dawley rats were subjected to intra-striatal injection of lipopolysaccharide (LPS) and treated with diosgenin. Stepping, Whisker, and Cylinder tests were carried out to determine the motor function, and the expression of tyrosine hydroxylase was detected by immunohistochemistry. The levels of multiple proinflammatory cytokines, oxidative stress related factors and proteins involved in Toll-like receptor (TLR)/nuclear factor kappa B (NF-κB) pathway were measured. The synergistic effect of environment enrichment on diosgenin was also investigated.

RESULTS

Intra-striatal injection of LPS caused motor deficits in rats, induced inflammatory response and oxidative stress response, and activated the TLR/NF-κB pathway both in vivo and in vitro. Diosgenin could attenuate the LPS-induced alterations. Enriched environment enhanced the effect of diosgenin to ameliorate the LPS-induced motor deficits in rats and decreased the protein levels of TLR2, TLR4, and nuclear NF-κB in diosgenin treated PD rats.

CONCLUSION

Diosgenin had a beneficial effect in LPS-induced rat PD models, by suppressing the TLR/NF-κB signaling pathway. Environmental enrichment could play a synergistic effect with diosgenin, by enhancing the inhibitory effect of diosgenin on the TLR/ NF-κB signaling pathway.

Alpha-synuclein at the nexus of genes and environment: the impact of environmental enrichment and stress on brain health and disease

Accumulation of alpha‐synuclein protein aggregates is the hallmark neuropathologic feature of synucleinopathies such as Parkinson’s disease. Rare point mutations and multiplications in SNCA, the gene encoding alpha‐synuclein, as well as other genetic alterations are linked to familial Parkinson’s disease cases with high penetrance and hence constitute major genetic risk factors for Parkinson’s disease. However, the preponderance of cases seems sporadic, most likely based on a complex interplay between genetic predispositions, aging processes and environmental influences. Deciphering the impact of these environmental factors and their interactions with the individual genetic background in humans is challenging and often requires large cohorts, complicated study designs, and longitudinal set‐ups. In contrast, rodent models offer an ideal system to study the influence of individual environmental aspects under controlled genetic background and standardized conditions. In this review, we highlight findings from studies examining effects of environmental enrichment mimicking stimulation of the brain by its physical and social surroundings as well as of environmental stressors on brain health in the context of Parkinson’s disease. We discuss possible internal molecular transducers of such environmental cues in Parkinson’s disease rodent models and emphasize their potential in developing novel avenues to much‐needed therapies for this still incurable disease.

This article is part of the Special Issue “Synuclein”

Resilience priming: Translational models for understanding resiliency and adaptation to early life adversity

Despite the increasing attention to early life adversity and its long-term consequences on health, behavior, and the etiology of neurodevelopmental disorders, our understanding of the adaptations and interventions that promote resiliency and rescue against such insults are underexplored. Specifically, investigations of the perinatal period often focus on negative events/outcomes. In contrast, positive experiences (i.e. enrichment/parental care//healthy nutrition) favorably influence development of the nervous and endocrine systems. Moreover, some stressors result in adaptations and demonstrations of later-life resiliency. This review explores the underlying mechanisms of neuroplasticity that follow some of these early life experiences and translates them into ideas for interventions in pediatric settings. The emerging role of the gut microbiome in mediating stress susceptibility is also discussed. Since many negative outcomes of early experiences are known, it is time to identify mechanisms and mediators that promote resiliency against them. These range from enrichment, quality parental care, dietary interventions and those that target the gut microbiota.

Basal ganglia and beyond: The interplay between motor and cognitive aspects in Parkinson's disease rehabilitation

Parkinson's disease (PD) is characterized by motor and cognitive dysfunctions, affecting the motor behaviour. We summarize evidence that the interplay between motor and cognitive approaches is crucial in PD rehabilitation. Rehabilitation is complementary to pharmacological therapy and effective in reducing the PD disturbances, probably acting by inducing neuroplastic effects. The motor behaviour results from a complex integration between cortical and subcortical areas, underlying the motor, cognitive and motivational aspects of movement. The close interplay amongst these areas makes possible to learn, control and express habitual-automatic actions, which are dysfunctional in PD. The physiopathology of PD could be considered the base for the development of effective rehabilitation treatments. As the volitional action control is spared in early-medium stages of disease, rehabilitative approaches engaging cognition permit to achieve motor benefits and appear to be the most effective for PD. We will point out data supporting the relevance of targeting both motor and cognitive aspects in PD rehabilitation. Finally, we will discuss the role of cognitive engagement in motor rehabilitation for PD.

An Enriched Environment Ameliorates Oxidative Stress and Olfactory Dysfunction in Parkinson's Disease with α-Synucleinopathy

Parkinson’s disease (PD) features nonmotor symptoms such as olfactory dysfunction referred to as hyposmia, an initial sign of disease progression. Metabolic dysfunction can contribute to neurodegenerative diseases, and various xenobiotics and endogenous compounds are also involved in the pathogenesis of PD. Although aerobic exercise was found to induce preservation or improvement in olfactory function in PD patients in a recent study, the exact underlying mechanism for this effect is not clear. We aimed to investigate the influence of an enriched environment (EE) on olfactory dysfunction especially via metabolic pathways related to detoxification enzymes. Eight-month-old transgenic (Tg) PD mice that overexpress human A53T α-synuclein (α-syn) were randomly allocated to an EE or standard conditions for 2 mo. The buried food test showed that EE group had significantly improved olfactory function compared to the control group. Reverse transcription polymerase chain reaction (PCR) and real-time quantitative PCR showed that expression of the detoxification enzymes––cytochrome P450 family 1 subfamily A member 2, paraoxonase 1, alcohol dehydrogenase 1, UDP glucuronosyltransferase family 2 member A1 complex locus, aldehyde oxidase homolog 2, and aldehyde glutathione peroxidase 6––was significantly increased in the olfactory bulb (OB) of the PD control group, but these enzymes were normalized in the EE group. Immunohistochemical staining of the OB showed that oxidative stress and nitrated α-syn were significantly increased in the control group but decreased in the EE group. In conclusion, we suggest that exposure to an EE decreases both oxidative stress and nitrated α-syn, resulting in normalized detoxification enzymes and amelioration of olfactory dysfunction.

Environmental Enrichment Prevents Transcriptional Disturbances Induced by Alpha-Synuclein Overexpression

Onset and progression of neurodegenerative disorders, including synucleinopathies such as Parkinson's disease, have been associated with various environmental factors. A highly compelling association from a therapeutic point of view has been found between a physically active lifestyle and a significantly reduced risk for Parkinson's disease. Mimicking such conditions in animal models by promoting physical activity, social interactions, and novel surroundings yields in a so-called enriched environment known to enhance adult neurogenesis, increase synaptic plasticity, and decelerate neuronal loss. Yet, the genes that connect beneficial environmental cues to the genome and delay disease-related symptoms have remained largely unclear. To identify such mediator genes, we used a 2 × 2 factorial design opposing genotype and environment. Specifically, we compared wildtype to transgenic mice overexpressing human SNCA, a key gene in synucleinopathies encoding alpha-synuclein, and housed them in a standard and enriched environment from weaning to 12 months of age before profiling their hippocampal transcriptome using RNA-sequencing. Under standard environmental conditions, differentially expressed genes were overrepresented for calcium ion binding, membrane, synapse, and other Gene Ontology terms previously linked to alpha-synuclein biology. Upregulated genes were significantly enriched for genes attributed to astrocytes, microglia, and oligodendrocytes. These disturbances in gene activity were accompanied by reduced levels of several presynaptic proteins and the immediate early genes EGR1 and NURR1. Intriguingly, housing transgenic animals in the enriched environment prevented most of these perturbations in gene activity. In addition, a sustained activation specifically in transgenic animals housed in enriched conditions was observed for several immediate early genes including Egr1, Nr4a2/Nurr1, Arc, and Homer1a. These findings suggest a compensatory mechanism through an enriched environment-activated immediate early gene network that prevented most disturbances induced by alpha-synuclein overexpression. This regulatory framework might harbor attractive targets for novel therapeutic approaches that mimic beneficial environmental stimuli.

The use of commercially available games for a combined physical and cognitive challenge during exercise for individuals with Parkinson's disease - a case series report

Complexity of an animal's environment has been shown to affect structural and functional changes in the brain. Evidence from animal models of Parkinson's disease (PD) suggests that exercising in an enriched environment may protect against the onset of Parkinsonian symptoms in rats that are exposed to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. The variety of activities and visual interfaces that can be created using commercially available gaming devices provide cognitively stimulating as well as physically challenging environments for exercise. This case series will: 1) elaborate on the rationale behind selection of specific games to target common deficits seen in PD; and 2) present preliminary results on clinical outcomes from three pilot participants who each completed six sessions of exercise. All three participants had mild to moderate PD. They were functionally independent individuals leading an active lifestyle. Participants were tested on the outcome measures before and after the six exercise sessions. On average, participants showed a 33.8% (22.8) improvement in functional reach test, 12.7% (35.0) improvement in single limb stance (SLS) time-right leg, 55.2% (33.9) improvement in SLS time-left leg, 11.9% (7.3) improvement in 6-min walk test, 2% (6.8) improvement in self-selected gait speed (GS), and 8.0% (5.8) improvement in fastest possible GS. Further investigation is warranted to study if these effects can be replicated over a longer exercise intervention and in a larger group, and if these effects are maintained at follow-up testing after the enriched exercise intervention is discontinued.

Environmental enrichment, alone or in combination with various pharmacotherapies, confers marked benefits after traumatic brain injury

Traumatic brain injury (TBI) is a significant health care issue that affects over ten million people worldwide. Treatment options are limited with numerous failures resulting from single therapies. Fortunately, several preclinical studies have shown that combination treatment strategies may afford greater improvement and perhaps can lead to successful clinical translation, particularly if one of the therapies is neurorehabilitation. The aim of this review is to highlight TBI studies that combined environmental enrichment (EE), a preclinical model of neurorehabilitation, with pharmacotherapies. A series of PubMed search strategies yielded only nine papers that fit the criteria. The consensus is that EE provides robust neurobehavioral, cognitive, and histological improvement after experimental TBI and that the combination of EE with some pharmacotherapies can lead to benefits beyond those revealed by single therapies. However, it is noted that EE can be challenged by drugs such as the acetylcholinesterase inhibitor, donepezil, and the antipsychotic drug, haloperidol, which attenuate its efficacy. These findings may help shape clinical neurorehabilitation strategies to more effectively improve patient outcome. Potential mechanisms for the EE and pharmacotherapy-induced effects are also discussed. This article is part of the Special Issue entitled "Neurobiology of Environmental Enrichment".

Protective Effects of Enriched Environment Against Transient Cerebral Ischemia-Induced Impairment of Passive Avoidance Memory and Long-Term Potentiation in Rats

Introduction

Enriched Environment (EE), a complex novel environment, has been demonstrated to improve synaptic plasticity in both injured and intact animals. The present study investigated the capacity of an early environmental intervention to normalize the impairment of passive avoidance memory and Long-Term Potentiation (LTP) induced by transient bilateral common carotid artery occlusion (2-vessel occlusion, 2VO) in rats.

Methods

After weaning, young Wistar rats (22 days old) were housed in EE or Standard Environment (SE) for 40 days. Transient (30-min) incomplete forebrain ischemia was induced 4 days before the passive avoidance memory test and LTP induction.

Results

The transient forebrain ischemia led to impairment of passive avoidance memory and LTP induction in the Perforant Path-Dentate Gyrus (PP-DG) synapses. Interestingly, housing and growing in EE prior to 2VO was found to significantly reverse 2VO-induced cognitive and LTP impairments.

Conclusion

Our results suggest that early housing and growing in EE exhibits therapeutic potential to normalize cognitive and LTP abnormalities induced by 2VO ischemic model in rats.

F. CARACTERIZACIÓN TEMPORO-ESPACIAL DEL PATRÓN DE MARCHA EN ROEDORES COMO MODELO ANIMAL DE LESIÓN CEREBRAL CEREBROVASCULAR

En la investigación sobre movimiento, la experimentación animal ha proporcionado fundamentación científica para la investigación clínica, mejorando procedimientos diagnósticos y de rehabilitación. Lesiones cerebrales en roedores pueden ser usadas para modelar síntomas locomotores, sensoriales y/o cognitivos. Con el propósito de determinar la funcionalidad locomotriz y sensorial en roedores, se han propuesto varios métodos de evaluación y pronóstico clínico para identificar y evaluar adaptaciones estructurales y mecanismos de neuro-recuperación. Esto ha permitido que métodos de intervención terapéutica, como el ejercicio físico, sean utilizados para restaurar funciones sensitivo-motoras y cognitivas en roedores y humanos. La extrapolación (translación) de los resultados de investigaciones en ciencias básicas a áreas clínicas supone la continua cooperación y retroalimentación entre investigadores y profesionales de la salud, favoreciendo la formulación de intervenciones terapéuticas más eficaces basadas en resultados obtenidos de la experimentación animal. El objetivo de esta revisión es exponer las principales deficiencias motoras y los métodos empleados para determinar la dificultad motriz en la marcha en roedores con lesión cerebrovascular, para lo cual se realizó una revisión de literatura, sobre términos definidos (MeSH), en las bases de datos PsychINFO, Medline y Web of Science, entre enero de 2000 y enero de 2017. Se excluyeron artículos de carácter cualitativo o narrativo, sin revisión por pares, disertaciones, tesis o trabajos de grado y resúmenes de conferencias. Se revisan algunas manifestaciones clínicas, su efecto en la locomotricidad en roedores, algunas metodologías usadas para generar lesiones y para estudiar la función motriz, los principales métodos de medición y algunos aspectos translacionales. 

The Neuroprotective Effects of Experience on Cognitive Functions: Evidence from Animal Studies on the Neurobiological Bases of Brain Reserve

Brain plasticity is the ability of the nervous system to change structurally and functionally in response to experience. By shaping brain structure and function, experience leads to the creation of a protective reserve that accounts for differences among individuals in susceptibility to age-related brain modifications and pathology. This review is aimed to address the biological bases of the experience-dependent "brain reserve" by describing the results of animal studies that focused on the neuroanatomical and molecular effects of environmental enrichment. More specifically, the effects at the cellular level are considered in terms of changes in neurogenesis, gliogenesis, angiogenesis, and synaptogenesis. Moreover, the effects at the molecular level are described, highlighting gene- and protein-level changes in neurotransmitter and neurotrophin expression. The experimental evidence for the basic biological consequences of environmental enrichment is described for healthy animals. Subsequently, by discussing the findings for animal models that mimic age-related diseases, the involvement of such plastic changes in supporting an organism as it copes with normal and pathological age-related cognitive decline is considered. On the whole, studies of the structural and molecular effects of environmental enrichment strongly support the neuroprotective action of a particularly stimulating lifestyle on cognitive functions. Our current level of understanding of these effects and mechanisms is such that additional and novel studies, systematic reviews, and meta-analyses are necessary to investigate the specific effects of the different components of environmental enrichment in both healthy and pathological models. Only in this way can comprehensive recommendations for proper life habits be developed.

Environmental Factors Promoting Neural Plasticity: Insights from Animal and Human Studies

We do not all grow older in the same way. Some individuals have a cognitive decline earlier and faster than others who are older in years but cerebrally younger. This is particularly easy to verify in people who have maintained regular physical activity and healthy and cognitively stimulating lifestyle and even in the clinical field. There are patients with advanced neurodegeneration, such as Alzheimer's disease (AD), that, despite this, have mild cognitive impairment. What determines this interindividual difference? Certainly, it cannot be the result of only genetic factors. We are made in a certain manner and what we do acts on our brain. In fact, our genetic basis can be modulated, modified, and changed by our experiences such as education and life events; daily, by sleep schedules and habits; or also by dietary elements. And this can be seen as true even if our experiences are indirectly driven by our genetic basis. In this paper, we will review some current scientific research on how our experiences are able to modulate the structural organization of the brain and how a healthy lifestyle (regular physical activity, correct sleep hygiene, and healthy diet) appears to positively affect cognitive reserve.

Early postnatal handling reduces hippocampal amyloid plaque formation and enhances cognitive performance in APPswe/PS1dE9 mice at middle age

In rodents, fragmented and low levels of maternal care have been implicated in age-related cognitive decline and the incidence and progression of Alzheimer's pathology. In contrast, enhancing early postnatal maternal care has been associated with improved cognitive function later in life. Here we examined whether early postnatal handling of mouse pups from postnatal days 2-9 enhanced maternal care and whether this affected cognition and Alzheimer pathology at 5 and 11months of age in the APPswe/PS1dE9 mouse model for Alzheimer's disease. Brief, 15min daily episodes of separating offspring from their dams from postnatal days 2-9 (early handling, EH) increased maternal care of the dam towards her pups upon reunion. At 11 (but not 5) months of age, EH APPswe/PS1dE1 mice displayed significantly reduced amyloid plaque pathology in the hippocampus. At this age, EH also prevented short-term working memory deficits while restoring impairments in contextual fear memory formation in APPswe/PS1dE9 mice. EH did not modulate amyloid pathology in the amygdala, nor did it affect auditory fear conditioning deficits in APPswe/PS1dE9 mice. We conclude that increased levels of maternal care during the early life period delays amyloid accumulation and cognitive decline in an Alzheimer's mouse model, involving the hippocampus, but not to the amygdala. These studies highlight the importance of the early postnatal period in modulating resilience to develop Alzheimer's pathology later in life.

Effects of Postnatal Enriched Environment in a Model of Parkinson's Disease in Adult Rats

Environmental enrichment is a widespread neuroprotective strategy during development and also in the mature nervous system. Several research groups have described that enriched environment in adult rats has an impact on the progression of Parkinson's disease (PD). The aim of our present study was to examine the effects of early, postnatal environmental enrichment after 6-hydroxydopamine-induced (6-OHDA) lesion of the substantia nigra in adulthood. Newborn Wistar rats were divided into control and enriched groups according to their environmental conditions. For environmental enrichment, during the first five postnatal weeks animals were placed in larger cages and exposed to intensive complex stimuli. Dopaminergic cell loss, and hypokinetic and asymmetrical signs were evaluated after inducing PD with unilateral injections of 6-OHDA in three-month-old animals. Treatment with 6-OHDA led to a significant cell loss in the substantia nigra of control animals, however, postnatal enriched circumstances could rescue the dopaminergic cells. Although there was no significant difference in the percentage of surviving cells between 6-OHDA-treated control and enriched groups, the slightly less dopaminergic cell loss in the enriched group compared to control animals resulted in less severe hypokinesia. Our investigation is the first to provide evidence for the neuroprotective effect of postnatal enriched environment in PD later in life.

Effect of resveratrol and environmental enrichment on biomarkers of oxidative stress in young healthy mice

Resveratrol (RESV) and Environmental Enrichment (EE) have been separately reported to protect organisms against various diseases. This study investigated the potential benefit of the combination of RESV and EE on biomarkers of oxidative stress in young healthy mice. Fifty mice of both sexes were randomly divided into five groups of 10 animals each: group I served as control, group II were maintained on alternate day feeding, group III received RESV 50 mg/kg, suspended in caboxymethylcellulose orally per kg/day. Group IV received CMC and kept in an Enriched Environment, group V received RESV + EE. The treatment lasted for 28 days. The animals were sacrificed 24 h after the last treatment and brain samples were collected for biochemical evaluation. The results obtained showed a significant decrease (P < 0.05) in malondialdehyde concentration in EE group and RESV treated group kept EE when compared to the control. A significant decrease was also observed in glutathione peroxidase activity in all the treatment groups when compared to the control. A significant decrease in GPx activities in RESV, EE and RESV + EE treated groups in male and female mice when compared to the control groups respectively. However, a significant increase in GPx activities was observed in EE group in male mice and EODF, RESV groups in female mice when compared to RESV + EE groups respectively. In conclusion, the result of our study indicates that EE possesses antioxidant properties by decreasing MDA concentration and attenuating lipid peroxidation in the brain of young Swiss albino mice.