Environmental enrichment: evidence for an unexpected therapeutic influence

Environmental Enrichment Improves the Recognition Memory in Adult Mice Following Social Isolation via Downregulation of Kv4.2 Potassium Channels

Recognition memory is a cognitive process that enables us to distinguish familiar objects and situations from new items, which is essential for mammalian survival and adaptation to a changing environment. Social isolation (SI) has been implicated as a detrimental factor for recognition memory. The medial prefrontal cortex (mPFC) has been shown to carry information concerning the relative familiarity of individual stimuli, and modulating neuronal function in this region may contribute to recognition memory. The present study aimed to investigate the neuronal mechanisms in the mPFC of environmental enrichment (EE) on recognition memory in adult mice following SI. Mice were assigned into three groups: control, SI, and SI + EE groups. Novel location recognition (NLR) and novel object recognition (NOR) tests were performed to evaluate the recognition memory. The levels of Kv4 channels were assessed by qRT-PCR and western blotting. The effects of SI and SI + EE on the excitability of pyramidal neurons in the mPFC were measured using whole-cell recording. We found that SI led to a reduction in the excitability of pyramidal neurons. Specifically, we have identified that the reduction in the firing activity of pyramidal neurons resulted from alterations in the function and expression of Kv4.2 channels. Furthermore, EE regulated Kv4.2 channels, normalized the activity of pyramidal neurons, and restored the behavioral deficits following SI. Thus, the roles of Kv4.2 channels in excitability of pyramidal neurons suggest that the Kv4.2 channels present a promising therapeutic target for recognition memory impairment.

Environmental enrichment attenuates depressive-like behavior in maternal rats by inhibiting neuroinflammation and apoptosis and promoting neuroplasticity

Gestational stress can exacerbate postpartum depression (PPD), for which treatment options remain limited. Environmental enrichment (EE) may be a therapeutic intervention for neuropsychiatric disorders, including depression, but the specific mechanisms by which EE might impact PPD remain unknown. Here we examined the behavioral, molecular, and cellular impact of EE in a stable PPD model in rats developed through maternal separation (MS). Maternal rats subjected to MS developed depression-like behavior and cognitive dysfunction together with evidence of significant neuroinflammation including microglia activation, neuronal apoptosis, and impaired synaptic plasticity. Expanding the duration of EE to throughout pregnancy and lactation, we observed an EE-associated reversal of MS-induced depressive phenotypes, inhibition of neuroinflammation and neuronal apoptosis, and improvement in synaptic plasticity in maternal rats. Thus, EE effectively alleviates neuroinflammation, neuronal apoptosis, damage to synaptic plasticity, and consequent depression-like behavior in mother rats experiencing MS-induced PPD, paving the way for new preventive and therapeutic strategies for PPD.

Neurodevelopmental Disruptions in Children of Preeclamptic Mothers: Pathophysiological Mechanisms and Consequences

Preeclampsia (PE) is a multisystem disorder characterized by elevated blood pressure in the mother, typically occurring after 20 weeks of gestation and posing risks to both maternal and fetal health. PE causes placental changes that can affect the fetus, particularly neurodevelopment. Its key pathophysiological mechanisms encompass hypoxia, vascular and angiogenic dysregulation, inflammation, neuronal and glial alterations, and disruptions in neuronal signaling. Animal models indicate that PE is correlated with neurodevelopmental alterations and cognitive dysfunctions in offspring and in humans, an association between PE and conditions such as cerebral palsy, autism spectrum disorder, attention deficit hyperactivity disorder, and sexual dimorphism has been observed. Considering the relevance for mothers and children, we conducted a narrative literature review to describe the relationships between the pathophysiological mechanisms behind neurodevelopmental alterations in the offspring of PE mothers, along with their potential consequences. Furthermore, we emphasize aspects pertinent to the prevention/treatment of PE in pregnant mothers and alterations observed in their offspring. The present narrative review offers a current, complete, and exhaustive analysis of (i) the pathophysiological mechanisms that can affect neurodevelopment in the children of PE mothers, (ii) the relationship between PE and neurological alterations in offspring, and (iii) the prevention/treatment of PE.

Digital Therapeutics for Improving Effectiveness of Pharmaceutical Drugs and Biological Products: Preclinical and Clinical Studies Supporting Development of Drug + Digital Combination Therapies for Chronic Diseases

Limitations of pharmaceutical drugs and biologics for chronic diseases (e.g., medication non-adherence, adverse effects, toxicity, or inadequate efficacy) can be mitigated by mobile medical apps, known as digital therapeutics (DTx). Authorization of adjunct DTx by the US Food and Drug Administration and draft guidelines on "prescription drug use-related software" illustrate opportunities to create drug + digital combination therapies, ultimately leading towards drug-device combination products (DTx has a status of medical devices). Digital interventions (mobile, web-based, virtual reality, and video game applications) demonstrate clinically meaningful benefits for people living with Alzheimer's disease, dementia, rheumatoid arthritis, cancer, chronic pain, epilepsy, depression, and anxiety. In the respective animal disease models, preclinical studies on environmental enrichment and other non-pharmacological modalities (physical activity, social interactions, learning, and music) as surrogates for DTx "active ingredients" also show improved outcomes. In this narrative review, we discuss how drug + digital combination therapies can impact translational research, drug discovery and development, generic drug repurposing, and gene therapies. Market-driven incentives to create drug-device combination products are illustrated by Humira® (adalimumab) facing a "patent-cliff" competition with cheaper and more effective biosimilars seamlessly integrated with DTx. In conclusion, pharma and biotech companies, patients, and healthcare professionals will benefit from accelerating integration of digital interventions with pharmacotherapies.

Levels of BDNF and NGF in adolescent rat hippocampus neonatally exposed to methamphetamine along with environmental alterations

Neurotrophins are proteins included in development and functioning of various processed in mammalian organisms. They are important in early development but as well as during adulthood. Brain - derived neurotrophic factor (BDNF) and nerve growth factor (NGF) have been previously linked with many psychiatric disorders such as depression and addiction. Since during postnatal development, brain undergoes various functional and anatomical changes, we included preweaning environment enrichment (EE), since enrichment has been linked with improved function and development of the several brain structure such as hippocampus (HP), in which we monitored these changes. On the other hand, social isolation has been linked with depression and anxiety-like behavior, therefore postweaning social isolation has been added to this model as well and animal were exposed to this condition till adolescence. We examined if all these three factors had impact on BDNF and NGF levels during three phases of adolescence - postnatal days (PDs) 28, 35 and 45. Our results show that EE did not increase BDNF levels neither in control or MA exposed animals and these results are similar for both direct and indirect exposure. On the other side, social separation after weaning did reduce BDNF levels in comparison to standard housing animals but this effect was reversed by direct MA exposure. In terms of NGF, EE environment increased its levels only in indirectly exposed controls and MA animals during late adolescence. On the other hand, social separation increased NGF levels in majority of animals.

Association of neighborhood deprivation with white matter connectome abnormalities in temporal lobe epilepsy

OBJECTIVE

Social determinants of health, including the effects of neighborhood disadvantage, impact epilepsy prevalence, treatment, and outcomes. This study characterized the association between aberrant white matter connectivity in temporal lobe epilepsy (TLE) and disadvantage using a US census-based neighborhood disadvantage metric, the Area Deprivation Index (ADI), derived from measures of income, education, employment, and housing quality.

METHODS

Participants including 74 TLE patients (47 male, mean age = 39.2 years) and 45 healthy controls (27 male, mean age = 31.9 years) from the Epilepsy Connectome Project were classified into ADI-defined low and high disadvantage groups. Graph theoretic metrics were applied to multishell connectome diffusion-weighted imaging (DWI) measurements to derive 162 × 162 structural connectivity matrices (SCMs). The SCMs were harmonized using neuroCombat to account for interscanner differences. Threshold-free network-based statistics were used for analysis, and findings were correlated with ADI quintile metrics. A decrease in cross-sectional area (CSA) indicates reduced white matter integrity.

RESULTS

Sex- and age-adjusted CSA in TLE groups was significantly reduced compared to controls regardless of disadvantage status, revealing discrete aberrant white matter tract connectivity abnormalities in addition to apparent differences in graph measures of connectivity and network-based statistics. When comparing broadly defined disadvantaged TLE groups, differences were at trend level. Sensitivity analyses of ADI quintile extremes revealed significantly lower CSA in the most compared to least disadvantaged TLE group.

SIGNIFICANCE

Our findings demonstrate (1) the general impact of TLE on DWI connectome status is larger than the association with neighborhood disadvantage; however, (2) neighborhood disadvantage, indexed by ADI, revealed modest relationships with white matter structure and integrity on sensitivity analysis in TLE. Further studies are needed to explore this relationship and determine whether the white matter relationship with ADI is driven by social drift or environmental influences on brain development. Understanding the etiology and course of the disadvantage-brain integrity relationship may serve to inform care, management, and policy for patients.

Τhe neuroprotective role of environmental enrichment against behavioral, morphological, neuroendocrine and molecular changes following chronic unpredictable mild stress: A systematic review

Environmental factors interact with biological and genetic factors influencing the development and well-being of an organism. The interest in better understanding the role of environment on behavior and physiology led to the development of animal models of environmental manipulations. Environmental enrichment (EE), an environmental condition that allows cognitive and sensory stimulation as well as social interaction, improves cognitive function, reduces anxiety and depressive-like behavior and promotes neuroplasticity. In addition, it exerts protection against neurodegenerative disorders, cognitive aging and deficits aggravated by stressful experiences. Given the beneficial effects of EE on the brain and behavior, preclinical studies have focused on its protective role as an alternative, non-invasive manipulation, to help an organism to cope better with stress. A valid, reliable and effective animal model of chronic stress that enhances anxiety and depression-like behavior is the chronic unpredictable mild stress (CUMS). The variety of stressors and the unpredictability in the time and sequence of exposure to prevent habituation, render CUMS an ethologically relevant model. CUMS has been associated with dysregulation of the hypothalamic-pituitary-adrenal axis, elevation in the basal levels of stress hormones, reduction in brain volume, dendritic atrophy and alterations in markers of synaptic plasticity. Although numerous studies have underlined the compensatory role of EE against the negative effects of various chronic stress regimens (e.g. restraint and social isolation), research concerning the interaction between EE and CUMS is sparse. The purpose of the current systematic review is to present up-to-date research findings regarding the protective role of EE against the negative effects of CUMS.

A Quasi-experimental of a Virtual Reality Content Intervention for Level of Comfort of Indonesian Cancer Patients

This study aims to determine the effect of virtual reality content on the comfort level of cancer patients. This study used a quasi-experimental non-equivalent control group design and was conducted on 60 cancer patients. The intervention uses the virtual reality content "My Comfortable Environment," which was developed based on Kolcaba's comfort theory. Comfort level was measured using the Shortened General Comfort Questionnaire. The Wilcoxon and Mann-Whitney U tests were used to determine the differences before and after the intervention within the group and between the study groups. There was a significant mean difference between pre-test and post-test in the intervention group with P < .000, Z = -4.785, and in the control group with P < .041, Z = -2.032. These results indicate that interventions with virtual reality content and guided imagery both affect the comfort level of cancer patients. However, if the test was conducted between groups, there was a significant difference between the intervention group and the control group with a P value of <.000. These results indicate that the virtual reality content intervention can significantly increase the level of patient comfort through modifying various aspects of patient comfort, especially environmental aspects.

Managing long-term wellness in captive sea turtles

Circumstances surrounding advances in stranding response and veterinary care have created a growing need for the long-term housing of captive sea turtles. However, the difficulty in recreating natural conditions in captive settings places a responsibility on caregivers to offset wild-type behavioural deficits with enrichment programming that is, preferably, commensurate with the limitations of each enclosure. Though standardised, multi-institutional behavioural monitoring programmes are currently lacking for marine turtles, facilities housing (or planning to house) sea turtles for the long-term are strongly advised to include 'wellness' as a fundamental part of their animal care protocol. Here, concepts of wellness and enrichment in sea turtles are reviewed, and a framework for developing longterm behavioural monitoring programming is provided.

The role of enriched environment in neural development and repair

In addition to genetic information, environmental factors play an important role in the structure and function of nervous system and the occurrence and development of some nervous system diseases. Enriched environment (EE) can not only promote normal neural development through enhancing neuroplasticity but also play a nerve repair role in restoring functional activities during CNS injury by morphological and cellular and molecular adaptations in the brain. Different stages of development after birth respond to the environment to varying degrees. Therefore, we systematically review the pro-developmental and anti-stress value of EE during pregnancy, pre-weaning, and “adolescence” and analyze the difference in the effects of EE and its sub-components, especially with physical exercise. In our exploration of potential mechanisms that promote neurodevelopment, we have found that not all sub-components exert maximum value throughout the developmental phase, such as animals that do not respond to physical activity before weaning, and that EE is not superior to its sub-components in all respects. EE affects the developing and adult brain, resulting in some neuroplastic changes in the microscopic and macroscopic anatomy, finally contributing to enhanced learning and memory capacity. These positive promoting influences are particularly prominent regarding neural repair after neurobiological disorders. Taking cerebral ischemia as an example, we analyzed the molecular mediators of EE promoting repair from various dimensions. We found that EE does not always lead to positive effects on nerve repair, such as infarct size. In view of the classic issues such as standardization and relativity of EE have been thoroughly discussed, we finally focus on analyzing the essentiality of the time window of EE action and clinical translation in order to devote to the future research direction of EE and rapid and reasonable clinical application.

Investigating the role of environmental enrichment initiated in adolescence against the detrimental effects of chronic unpredictable stress in adulthood: Sex-specific differences in behavioral and neuroendocrinological findings

Environmental Enrichment (EE) improves cognitive function and enhances brain plasticity, while chronic stress increases emotionality, impairs learning and memory, and has adverse effects on brain anatomy and biochemistry. We explored the beneficial role of environmental enrichment initiated in adolescence against the negative outcomes of Chronic Unpredictable Stress (CUS) during adulthood on emotional behavior, cognitive function, as well as somatic and neuroendocrine markers in both sexes. Adolescent Wistar rats housed either in enriched or standard housing conditions for 10 weeks. On postnatal day 66, a subgroup from each housing condition was daily exposed to a 4-week stress protocol. Following stress, adult rats underwent behavioral testing to evaluate anxiety, exploration/locomotor activity, depressive-like behavior and spatial learning/memory. Upon completion of behavioral testing, animals were exposed to a 10-m stressful event to test the neuroendocrine response to acute stress. CUS decreased body weight gain and increased adrenal weight. Some stress-induced behavioral adverse effects were sex-specific since learning impairments were limited to males while depressive-like behavior to females. EE housing protected against CUS-related behavioral deficits and body weight loss. Exposure to CUS affected the neuroendocrine response of males to acute stress as revealed by the increased corticosterone levels. Our findings highlight the significant role of EE in adolescence as a protective factor against the negative effects of stress and underline the importance of inclusion of both sexes in animal studies.

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.

Training the brain: could it improve multiple sclerosis treatment?

Multiple sclerosis (MS) is a neurological disease characterized by neuroinflammation, demyelination and axonal degeneration along with loss of function in the central nervous system. For many years, research in MS has focused on the efficacy of pharmacological treatments. However, during the last years, many publications have been dedicated to the study of the efficacy of non-pharmacological strategies, such as physical exercise and cognitive training. Beneficial effects of the combination of both strategies on cognitive function have been described in both ageing adults and patients with neurodegenerative diseases, such as MS. The analysis of combining both physical and cognitive stimulation can be summarized by the environmental enrichment (EE) experiments, which are more suitable for animal models. EE refers to housing conditions consisting of exercise and cognitive and social stimulation. In this review, we will summarize the available studies that describe the influence of EE in both MS patients and MS animal models.

Environmental enrichment rescues cognitive impairment with suppression of TLR4-p38MAPK signaling pathway in vascular dementia rats

Increasing evidence demonstrated the promising effects of environmental enrichment (EE) on brain recovery and cognitive performance in animal models of various diseases. However, the effect and molecular mechanisms of EE on vascular dementia (VD) remain to be studied. The aim of this study was to explore the effect of EE on cognitive decline and its mechanism. Sprague-Dawley rats underwent 2-vessel occlusion (2-VO) surgery or sham operation. Subsequently, rats were kept in EE for 4 weeks. In Morris water maze (MWM) test, we demonstrated that EE significantly improved cognitive function in rats with VD. HE staining exhibited morphological changes of neurons and quantitative analysis of TUNEL showed increased apoptotic neurons in hippocampal CA1 region following 2-VO. Results from RT-qPCR showed up-regulation of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) after 2-VO. Western blotting analysis revealed enhanced toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MYD88) and phosphorylated p38 mitogen-activated protein kinase (p-p38MAPK) in 2-VO rats. Whereas administration of EE reduced apoptotic neurons, down-regulated inflammatory factors. Moreover, EE suppressed protein expression of TLR4-p38MAPK pathway. Spearman correlation analysis showed that improved cognitive function was associated with decreased expression of TLR4 and p-p38MAPK proteins. Thus, our study proved that EE has a prominent effect on cognitive impairment and neuronal damage following 2-VO by attenuating inflammation and apoptosis, which may be realized via inhibiting the TLR4-P38MAPK signaling pathway.

Reporting animal research: Explanation and elaboration for the ARRIVE guidelines 2.0

Improving the reproducibility of biomedical research is a major challenge. Transparent and accurate reporting is vital to this process; it allows readers to assess the reliability of the findings and repeat or build upon the work of other researchers. The ARRIVE guidelines (Animal Research: Reporting In Vivo Experiments) were developed in 2010 to help authors and journals identify the minimum information necessary to report in publications describing in vivo experiments. Despite widespread endorsement by the scientific community, the impact of ARRIVE on the transparency of reporting in animal research publications has been limited. We have revised the ARRIVE guidelines to update them and facilitate their use in practice. The revised guidelines are published alongside this paper. This explanation and elaboration document was developed as part of the revision. It provides further information about each of the 21 items in ARRIVE 2.0, including the rationale and supporting evidence for their inclusion in the guidelines, elaboration of details to report, and examples of good reporting from the published literature. This document also covers advice and best practice in the design and conduct of animal studies to support researchers in improving standards from the start of the experimental design process through to publication.

The effects of environmental enrichment on skin barrier recovery in humans: a randomised trial

This study investigated whether environmental enrichment (EE) could reduce stress and improve wound healing in humans. 120 participants underwent a standardised tape-stripping procedure and were then randomised to interact for 30 minutes with one of three EE interventions (comfort blankets as tactile enrichment, music as auditory enrichment or a Paro robot as multi-sensory enrichment) or to a control group. Skin barrier recovery (SBR) was measured using transepidermal water loss at baseline, after tape-stripping and after the intervention. Psychological variables, cortisol and alpha-amylase were measured at the three time-points. SBR did not significantly differ between the EE conditions and the control condition. The music condition had higher stimulation levels than the control condition, and the comfort condition had significantly lower relaxation levels than the control condition after the intervention. The EE interventions tested were not beneficial for wound healing compared to a control group. Limitations were that the sample were not stressed and an active control condition was used.

Mapping accumulative whole-brain activities during environmental enrichment with manganese-enhanced magnetic resonance imaging

An enriched environment (EE) provides multi-dimensional stimuli to the brain. EE exposure for days to months induces functional and structural neuroplasticity. In this study, manganese-enhanced magnetic resonance imaging (MEMRI) was used to map the accumulative whole-brain activities associated with a 7-day EE exposure in freely-moving adult male mice, followed by c-Fos immunochemical assessments. Relative to the mice residing in a standard environment (SE), the mice subjected to EE treatment had significantly enhanced regional MEMRI signal intensities in the prefrontal cortex, somatosensory cortices, basal ganglia, amygdala, motor thalamus, lateral hypothalamus, ventral hippocampus and midbrain dopaminergic areas at the end of the 7-day exposure, likely attributing to enhanced Mn²⁺ uptake/transport associated with brain activities at both the regional and macroscale network levels. Some of, but not all, the brain regions in the EE-treated mice showing enhanced MEMRI signal intensity had accompanying increases in c-Fos expression. The EE-treated mice were also found to have significantly increased overall amount of food consumption, decreased body weight gain and upregulated tyrosine hydroxylase (TH) expression in the midbrain dopaminergic areas. Taken together, these results demonstrated that the 7-day EE exposure was associated with elevated cumulative activities in the nigrostriatal, mesolimbic and corticostriatal circuits underpinning reward, motivation, cognition, motor control and appetite regulation. Such accumulative activities might have served as the substrate of EE-related neuroplasticity and the beneficial effects of EE treatment on neurological/psychiatric conditions including drug addiction, Parkinson's disease and eating disorder.

Environmental enrichment improves cognitive symptoms and pathological features in a focal model of cortical damage of multiple sclerosis

Multiple Sclerosis (MS) is a neuroinflammatory disease affecting white and grey matter, it is characterized by demyelination, axonal degeneration along with loss of motor, sensitive and cognitive functions. MS is a heterogeneous disease that displays different clinical courses: relapsing/remitting MS (RRMS), and MS progressive forms: primary progressive (PPMS) and secondary progressive (SPMS). Cortical damage in the progressive MS forms has considerable clinical relevance due to its association with cognitive impairment and disability progression in patients. One treatment is available for the progressive forms of the disease, but none are specific for cognitive deficits. We developed an animal model that reflects most of the characteristics of the cortical damage, such as cortical neuroinflammation, demyelination, neurodegeneration and meningeal inflammation, which was associated with cognitive impairment. Cognitive rehabilitation, exercise and social support have begun to be evaluated in patients and animal models of neurodegenerative diseases. Environmental enrichment (EE) provides exercise as well as cognitive and social stimulation. EE has been demonstrated to exert positive effects on cognitive domains, such as learning and memory, and improving anxiety-like symptoms. We proposed to study the effect of EE on peripherally stimulated cortical lesion induced by the long term expression of interleukin IL-1β (IL-1β) in adult rats. Here, we demonstrated that EE: 1) reduces the peripheral inflammatory response to the stimulus, 2) ameliorates cognitive deficits and anxiety-like symptoms, 3) modulates neurodegeneration, demyelination and glial activation, 4) regulates neuroinflammation by reducing the expression of pro-inflammatory cytokines and enhancing the expression of anti-inflammatory ones. Our findings correlate with the fact that EE housing could be considered an effective non- pharmacological therapeutic agent that can synergistically aid in the rehabilitation of the disease.

Enriched Environmental Conditions Modify the Gut Microbiome Composition and Fecal Markers of Inflammation in Parkinson's Disease

Recent findings suggest an implication of the gut microbiome in Parkinson's disease (PD) patients. PD onset and progression has also been linked with various environmental factors such as physical activity, exposure to pesticides, head injury, nicotine, and dietary factors. In this study, we used a mouse model, overexpressing the complete human SNCA gene (SNCA-TG mice) modeling familial and sporadic forms of PD to study whether environmental conditions such as standard vs. enriched environment changes the gut microbiome and influences disease progression. We performed 16S rRNA DNA sequencing on fecal samples for microbiome analysis and studied fecal inflammatory calprotectin from the colon of control and SNCA-TG mice kept under standard environment (SE) and enriched environment (EE) conditions. The overall composition of the gut microbiota was not changed in SNCA-TG mice compared with WT in EE with respect to SE. However, individual gut bacteria at genus level such as Lactobacillus sp. was a significant changed in the SNCA-TG mice. EE significantly reduced colon fecal inflammatory calprotectin protein in WT and SNCA-TG EE compared to SE. Moreover, EE reduces the pro-inflammatory cytokines in the feces and inflammation inducing genes in the colon. Our data suggest that an enriched social environment has a positive effect on the induction of SNCA mediated inflammation in the intestine and by modulating anti-inflammatory gut bacteria.

Aerobic exercise combined with environmental enrichment improves spatial memory and enhances neuroligin 1 expression: an animal study

BACKGROUND Numerous studies have revealed that aerobic exercise (AE) or environmental enrichment (EE) exert positive effects on the molecular, cellular, and structural changes responsible for functional plasticity. Therefore, this study was aimed to investigate whether the combination of AE and EE yields a greater effect on spatial memory and increases the expression of the adhesion molecule neuroligin 1 compared with either of the therapies alone. METHODS Twenty 6-month-old male Wistar rats were randomly divided into four groups: (1) the control group (C), (2) the AE group, (3) the EE group, and (4) the AE-EE group. Escape latency in a Water-E-maze (WEM) task was used as a parameter to assess spatial memory function. Neuroligin 1 protein expression was examined via the immunohistochemistry (IHC) technique followed by IHC optical density (OD) score analysis of the CA1 hippocampal region. RESULTS Data acquired from the WEM task show that escape latency progressively decreased over time in all groups. However, animals in the AE-EE group required less time to complete the task compared with those in the control, AE, and EE groups. IHC OD scores revealed that the combination of AE and EE caused the highest expression of neuroligin 1 in the CA1 hippocampal region among the therapies studied. Statistical analysis indicated significant differences in OD score between the AE-EE and control, AE, and EE groups (p ≤ 0.001). CONCLUSIONS The combination of AE and EE rats increased neuroligin 1 expression and improved the spatial memory of male Wistar rats compared with application of either therapy alone.

Environmental enrichment restores the reduced expression of cerebellar synaptophysin and the motor coordination impairment in rats prenatally treated with betamethasone

Preterm babies treated with synthetic glucocorticoids in utero exhibit behavioural alterations and disturbances in brain maturation during postnatal life. Accordingly, it has been shown in preclinical studies that SGC exposure at a clinical dose alters the presynaptic and postsynaptic structures and results in synaptic impairments. However, the precise mechanism by which SGC exposure impairs synaptic protein expression and its implications are not fully elucidated. Therefore, the purpose of this study was to investigate the effect of prenatal exposure to a clinical dose of betamethasone on the pre- and postsynaptic proteins expression in the developing rat cerebellum and prefrontal cortex, whose synchronized synaptic activity is crucial for motor control and learning. Consequently, the first objective of the present study was to determine whether prenatal betamethasone -equivalent to the clinically used dose- alters cerebellar vermal and cortical expression of synaptophysin, synaptotagmin I, post-synaptic density protein 95 and gephyrin - four important pre- and post-synaptic proteins, respectively- at a relevant adolescent stage. In addition, our second objective was to assess whether prenatal betamethasone administration induced coordination impairment using a rotarod test. On the other hand, it has been shown that the environmental enrichment is capable of improving synaptic transmission and recovering various behavioural impairments. Nevertheless, there is not enough information about the effect of this non-pharmacological preclinical approach on the regulation of this cerebellar and cortical synaptic proteins. Therefore, the third objective of this study was to examine whether environmental enrichment exposure could recover the possible molecular and behavioural impairments in the offspring at the same developmental stage. The principal data showed that adolescent rats prenatally treated with betamethasone exhibited underexpression of synaptophysin in the vermal cerebellum, but not change in levels of synaptotagmin I, post-synaptic density protein 95 and gephyrin. Analysis of the same pre- and post-synaptic proteins no showed differences in the frontal cortex of the same rats. These results were accompanied by an increase in the number of falls in the rotarod test, when the speed of rotation was fixed and when it was in acceleration, which means motor coordination impairments. Importantly, we found that environmental enrichment restores the betamethasone-induced reduction in the cerebellar synaptophysin together with a recover in the motor coordination impairments in prenatally betamethasone-exposed adolescent rats.

Effects of Single Cage Housing on Stress, Cognitive, and Seizure Parameters in the Rat and Mouse Pilocarpine Models of Epilepsy

Many experimental approaches require housing rodents in individual cages, including in epilepsy research. However, rats and mice are social animals; and individual housing constitutes a stressful situation. The goal of the present study was to determine the effects of individual housing as compared to conditions maintaining social contact on stress markers and epilepsy. Control male mice socially housed during pretest and then transferred to individual cages for six weeks displayed anhedonia, increased anxiety and biological markers of stress as compared to pretest values or mice kept socially housed during six weeks. Pilocarpine (pilo)-treated mice housed together showed increased levels of anhedonia, anxiety and stress markers as well as decreased cognitive performance as compared to the control group. The differences were more significant in pilo-treated mice housed individually. Anxiety correlated linearly with cognitive performance and stress markers independently of the experimental conditions. In the male rat pilo model, seizures were sixteen times more frequent in singly housed animals as compared to animals kept in pairs. Daily interactions with an experimenter in otherwise singly housed animals was sufficient to produce results identical to those found in animals kept in pairs. We propose that social isolation produces a severe phenotype in terms of stress and seizure frequency as compared to animals maintaining social contact (at least in these two models), a factor that needs to be taken into account for data interpretation, in particular for preclinical studies.

Experience-Dependent Regulation of Cajal-Retzius Cell Networks in the Developing and Adult Mouse Hippocampus

In contrast to their near-disappearance in the adult neocortex, Cajal-Retzius cells have been suggested to persist longer in the hippocampus. A distinctive feature of the mature hippocampus, not maintained by other cortical areas, is its ability to sustain adult neurogenesis. Here, we have investigated whether environmental manipulations affecting hippocampal postnatal neurogenesis have a parallel impact on Cajal-Retzius cells. We used multiple mouse reporter lines to unequivocally identify Cajal-Retzius cells and quantify their densities during postnatal development. We found that exposure to an enriched environment increased the persistence of Cajal-Retzius cells in the hippocampus, but not in adjacent cortical regions. We did not observe a similar effect for parvalbumin-expressing interneurons, which suggested the occurrence of a cell type-specific process. In addition, we did not detect obvious changes either in Cajal-Retzius cell electrophysiological or morphological features, when compared with what previously reported in animals not exposed to enriched conditions. However, optogenetically triggered synaptic output of Cajal-Retzius cells onto local interneurons was enhanced, consistent with our observation of higher Cajal-Retzius cell densities. In conclusion, our data reveal a novel form of hippocampal, cell type-specific, experience-dependent network plasticity. We propose that this phenomenon may be involved in the regulation of enrichment-dependent enhanced hippocampal postnatal neurogenesis.

Therapeutic effects of combination environmental enrichment with necrostatin-1 on cognition following vascular cognitive impairment in mice

Cognitive dysfunction resulting from the reduction of cerebral blood flow has been defined as “vascular cognitive impairment” (VCI) which has become the second cause of dementia only after Alzheimer’s disease (AD) and arouses great concerns. There is accumulating evidence that environmental enrichment (EE) can induce functional and anatomical alterations and then bring about overt improvement in memory and learning tasks in many injury paradigms, including ischemic brain injury. Moreover, necrostatin-1 (Nec-1), the special inhibitor of necroptosis, improved functional outcomes following ischemic brain injury and AD. The question of whether and what effect EE and EE + Nec-1 could bring about on cognitive performance and microenvironment and histopathological consequences in the mice suffering from VCI is still unclear. In this study, we investigated this question using the bilateral common carotid artery stenosis (BCAS) mouse model. A week after surgical operation for BCAS, mice were reared for 3 weeks either in standard housing condition or in an EE consisting of special cage filling with various stimulatory items. The results found that the mice in the BCAS + EE and BCAS + EE + Nec-1 groups showed significantly shorter latencies and distances to reach the platform in behavioral tests versus untreated mice at 4 weeks after BCAS surgery. However, three injured groups showed significant deficits compared with the sham group ( P < 0.05). In addition, there were no differences between the EE-reared mice and EE + Nec-1-treated mice except in the level of expression of inflammation cytokines. Our results indicated that noninvasive environmental stimulation is beneficial in ameliorating cognitive deficits and inflammation response in mice following VCI and that Nec-1 enhanced the inhibitory effect of EE on inflammation response.

Housing and road transport modify the brain neurotransmitter systems of pigs: Do pigs raised in different conditions cope differently with unknown environments?

How housing and transport conditions may affect welfare in porcine production is a leading topic in livestock research. This study investigated whether pigs present a different neurological response to management conditions and to ascertain whether pigs living partially outdoors cope differently with road transport-associated stress. Twenty-four female pigs were divided in two groups: one living indoors (ID, n = 12) and the other housed combining indoor conditions with 4 hours per day of outdoor pasture (OD, n = 12). After one month, one set of animals from each housing condition were driven in a truck to the slaughterhouse in low-stress conditions (5 min drive, no mixing groups, soft management, LS group, n = 12) or high-stress conditions (2 hours drive, mixing groups, harsh management, HS group, n = 12). At the slaughterhouse, blood was collected, and the prefrontal cortex (PFC) and the hippocampus (HC) dissected. OD pigs had lower serum haptoglobin and increased dopaminergic pathway (DA-system) in the PFC, suggesting that living outdoors increases their wellbeing. HS conditions increased serum creatine kinase (CK) and affected several brain pathways: activation of the noradrenergic (NA-system) and DA -system in the PFC and the activation of the DA-system and an increase in c-Fos as well as a decrease in brain-derived neurotrophic factor (BDNF) in the HC. The serotonergic system (5-HT-system) was mildly altered in both areas. There was an interaction between housing and transport in serum NA and the DA-system in the HC, indicating that living conditions affected the response to stress. Multivariate analysis was able to discriminate the four animal groups. In conclusion, this work indicates that housing conditions and road transport markedly modifies the neurophysiology of pigs, and suggests that animals raised partially outdoors respond differently to transport-associated stress than animals raised indoors, indicating that they cope differently with unknown environments.

Enriched Environment Significantly Reduced Senile Plaques in a Transgenic Mice Model of Alzheimer's Disease, Improving Memory

Alzheimer's disease (AD) is associated with a progressive dementia, and there is good evidence that it is more pronounced in individuals that have fewer stimuli during their lives. Environmental stimulation promotes morphological and functional changes in the brain, leading to amplification of cognitive functions, and has been described in humans and animals. In this study, we evaluated the effects of enriched environment (EE) stimulation on spatial memory and senile plaque formation in transgenic mice PDGFB-APPSwInd (TG) that overexpress the human amyloid precursor protein, normally resulting in an increased density of senile plaques. We compared this group of EE stimulated transgenic mice (TG-EE) with an EE stimulated control group of age-matched C57Bl/6 wild type animals (WT-EE). Both groups were exposed to EE stimulation between the ages of 8 and 12 months. As controls of the experiment, there were a group of TG mice not exposed to EE (TG-Ctrl) and a group of WT mice not exposed to EE (WT-Ctrl). The TG-EE group presented improved spatial memory when compared to the TG-Ctrl animals. In addition, the TG-EE group showed a 69.2% reduction in the total density of senile plaques in the hippocampus when compared to the TG-Ctrl group. In this group, the concentration of senile plaques was greater in the dorsal part of the hippocampus, which is linked to spatial localization, and the reduction of this density after the submission to EE was as high as 85.1%. EE stimulation had no effect on the density of amyloid-β (Aβ) oligomers. However, amyloid scavenger receptor class B member 1 (SR-B1) density was significantly decreased in the TG-Ctrl mice, but not in the TG-EE mice, suggesting that cognitive stimulation had an effect on the formation of a cognitive reserve that could prevent the accumulation of senile plaques. It is suggested that the stimulation of old mice by EE for 4 months led to the formation of brain resilience that protected the brain from the deposition of senile plaques, one of the hallmarks of AD, leading to improvement in spatial memory.

Enriched environment elevates expression of growth associated protein-43 in the substantia nigra of SAMP8 mice

An enriched environment protects dopaminergic neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neuronal injury, but the underlying mechanism for this is not clear. Growth associated protein-43 (GAP-43) is closely associated with neurite outgrowth and axon regeneration during neural development. We speculate that an enriched environment can reduce damage to dopaminergic neurons by affecting the expression of GAP-43. This study is designed to test this hypothesis. Three-month-old female senescence-accelerated mouse prone 8 (SAMP8) mice were housed for 3 months in an enriched environment or a standard environment. These mice were then subcutaneously injected in the abdomen with 14 mg/kg MPTP four times at 2-hour intervals. Morris water maze testing demonstrated that learning and memory abilities were better in the enriched environment group than in the standard environment group. Reverse-transcription polymerase chain reaction, immunohistochemistry and western blot assays showed that mRNA and protein levels of GAP-43 in the substantia nigra were higher after MPTP application in the enriched environment group compared with the standard environment group. These findings indicate that an enriched environment can increase GAP-43 expression in SAMP8 mice. The upregulation of GAP-43 may be a mechanism by which an enriched environment protects against MPTP-induced neuronal damage.

Enriched Physical Environment Attenuates Spatial and Social Memory Impairments of Aged Socially Isolated Mice

BACKGROUND

Social isolation in the elderly is one of the principal health risks in an aging society. Physical environmental enrichment is shown to improve sensory, cognitive, and motor functions, but it is unknown whether environmental enrichment can protect against brain impairments caused by social isolation.

METHODS

Eighteen-month-old mice were housed, either grouped or isolated, in a standard or enriched environment for 2 months, respectively. Behavioral tests were performed to evaluate cognitive functional and social interaction ability. Synaptic protein levels, myelination, neuroinflammation, brain derived neurotrophic factor, and NOD-like receptor protein 3 inflammasome signaling pathways were examined in the medial prefrontal cortex and hippocampus.

RESULTS

Isolated aged mice exhibited declines in spatial memory and social memory compared with age-matched littermates living within group housing. The aforementioned memory malfunctions were mitigated in isolated aged mice that were housed in a large cage with a running wheel and novel toys. Enriched housing prevented synaptic protein loss, myelination defects, and downregulation of brain derived neurotrophic factor, while also increasing interleukin 1 beta and tumor necrosis factor alpha in the medial prefrontal cortex and hippocampus of isolated mice. In addition, activation of glial cells and NOD-like receptor protein 3 inflammasomes was partially ameliorated in the hippocampus of isolated mice treated with physical environmental enrichment.

CONCLUSIONS

These results suggest that an enriched physical environment program may serve as a nonpharmacological intervention candidate to help maintain healthy brain function of elderly people living alone.

Odor Enrichment Increases Hippocampal Neuron Numbers in Mouse

The hippocampus and olfactory bulb incorporate new neurons migrating from neurogenic regions in the brain. Hippocampal atrophy is evident in numerous neurodegenerative disorders, and altered hippocampal neurogenesis is an early pathological event in Alzheimer's disease. We hypothesized that hippocampal neurogenesis is affected by olfactory stimuli through the neural pathway of olfaction-related memory. In this study, we exposed mice to novel pleasant odors for three weeks and then assessed the number of neurons, non-neuronal cells (mainly glia) and proliferating cells in the hippocampus and olfactory bulb, using the isotropic fractionator method. We found that the odor enrichment significantly increased the neuronal cell numbers in the hippocampus, and promoted cell proliferation and neurogenesis in the olfactory bulb. In contrast, the glial cell numbers remained unchanged in both of the regions. Our results suggest that exposure to novel odor stimuli promotes hippocampal neurogenesis and support the idea that enriched environments may delay the onset or slow down the progression of neurodegenerative disorders.

Environmental Enrichment as a Positive Behavioral Intervention Across the Lifespan

BACKGROUND

In recent decades, the interest in behavioral interventions has been growing due to the higher prevalence of age-related cognitive impairments. Hence, behavioral interventions, such as cognitive stimulation and physical activity, and along with these, our lifestyle (education level, work position, frequency of cognitive and social activities) have shown important benefits during the cognitive impairment, dementia and even recovery after brain injury. This is due to the fact that this type of intervention and activities promote the formation of a cognitive and brain reserve that allows tolerating brain damage during a long period of time without the appearance of cognitive symptoms. With regard to this, animal models have proved very useful in providing information about the brain mechanisms involved in the development of these cognitive and brain reserves and how they interact with each other.

METHODS

We summarize several studies showing the positive effects of Environmental Enrichment (EE), understood as a housing condition in which animals benefit from the sensory, physical, cognitive and social stimulation provided, on brain and cognitive functions usually impaired during aging.

RESULTS

Most of studies have shown that EE is a successful protocol to improve cognitive functions and reduce anxiety-related behaviors across the lifespan, as well as in animal models of neurodegenerative diseases.

CONCLUSION

Therefore, EE is a laboratory condition in which some aspects of an active lifestyle are reproduced.

Kainic Acid Induces mTORC1-Dependent Expression of Elmo1 in Hippocampal Neurons

Epileptogenesis is a process triggered by initial environmental or genetic factors that result in epilepsy and may continue during disease progression. Important parts of this process include changes in transcriptome and the pathological rewiring of neuronal circuits that involves changes in neuronal morphology. Mammalian/mechanistic target of rapamycin (mTOR) is upregulated by proconvulsive drugs, e.g., kainic acid, and is needed for progression of epileptogenesis, but molecular aspects of its contribution are not fully understood. Since mTOR can modulate transcription, we tested if rapamycin, an mTOR complex 1 inhibitor, affects kainic acid-evoked transcriptome changes. Using microarray technology, we showed that rapamycin inhibits the kainic acid-induced expression of multiple functionally heterogeneous genes. We further focused on engulfment and cell motility 1 (Elmo1), which is a modulator of actin dynamics and therefore could contribute to pathological rewiring of neuronal circuits during epileptogenesis. We showed that prolonged overexpression of Elmo1 in cultured hippocampal neurons increased axonal growth, decreased dendritic spine density, and affected their shape. In conclusion, data presented herein show that increased mTORC1 activity in response to kainic acid has no global effect on gene expression. Instead, our findings suggest that mTORC1 inhibition may affect development of epilepsy, by modulating expression of specific subset of genes, including Elmo1, and point to a potential role for Elmo1 in morphological changes that accompany epileptogenesis.

Enriched environment and Mash1 transfection affect neural stem cell differentiation after transplantation into the adult somatosensory cortex

Neural stem cell (NSC) transplantation is a promising therapeutic modality for various nervous-system disorders; however, poor survival and differentiation of the transplanted NSCs limit their therapeutic efficacy. This study elucidated the effect of additive rehabilitative therapy with enriched environment (EE) and of achaete-scute homolog 1 (Mash1) and neurogenin2 (Ngn2) transduction on the fate of NSCs (P28-P35) transplanted into the primary somatosensory cortex (PSC) of mice. NSCs transplanted into the PSC differentiated into neurons and astrocytes and exhibited typical excitatory and synaptic response in mice housed in standard cages or in the EE. After EE exposure, significantly enhanced differentiation of transplanted NSCs into neuronal nuclear antigen-positive neurons was observed, whereas marked inhibition of the differentiation of transplanted NSCs into astrocytes was noted. Additionally, the proportion of GAD+ cells among GFP+/NeuN+ cells decreased following EE exposure. Furthermore, Mash1-transduced NSCs exhibited significantly enhanced populations of glutamic acid decarboxylase-negative neurons, whereas Ngn2-transduced NPCs did not.

Environmental enrichment induces behavioural disturbances in neuropeptide Y knockout mice

Environmental enrichment (EE) refers to the provision of a complex and stimulating housing condition which improves well-being, behaviour and brain function of laboratory animals. The mechanisms behind these beneficial effects of EE are only partially understood. In the current report, we describe a link between EE and neuropeptide Y (NPY), based on findings from NPY knockout (KO) mice exposed to EE. Relative to EE-housed wildtype (WT) animals, NPY KO mice displayed altered behaviour as well as molecular and morphological changes in amygdala and hippocampus. Exposure of WT mice to EE reduced anxiety and decreased central glucocorticoid receptor expression, effects which were absent in NPY KO mice. In addition, NPY deletion altered the preference of EE items, and EE-housed NPY KO mice responded to stress with exaggerated hyperthermia, displayed impaired spatial memory, had higher hippocampal brain-derived neurotrophic factor mRNA levels and altered hippocampal synaptic plasticity, effects which were not seen in WT mice. Accordingly, these findings suggest that NPY contributes to the anxiolytic effect of EE and that NPY deletion reverses the beneficial effects of EE into a negative experience. The NPY system could thus be a target for “enviromimetics”, therapeutics which reproduce the beneficial effects of enhanced environmental stimulation.

Effects of enriched environment on alterations in the prefrontal cortex GFAP- and S100B-immunopositive astrocytes and behavioral deficits in MK-801-treated rats

A plethora of studies have indicated that enriched environment (EE) paradigm provokes plastic and morphological changes in astrocytes with accompanying increments of their density and positively affects the behavior of rodents. We also previously documented that EE could be employed to preclude several behavioral abnormalities, mainly cognitive deficits, attributed to postnatal N-methyl-d-aspartate (NMDA) receptor antagonist (MK-801) treatment, as a rodent model of schizophrenia (SCH) aspects. Given this, the current study quantitatively investigated the number of cells, presumed to be astrocytes, expressing two astroglia-associated proteins (S100B and glial fibrillary acidic protein (GFAP)) by immunohistochemistry in the prefrontal cortex (PFC), along with anxiety and passive avoidance (PA) learning behaviors by utilizing elevated plus maze (EPM) and shuttle-box tests, in MK-801-treated male wistar rats submitted to EE and non-EE rats. Following a treatment regime of sub-chronic MK-801 (1.0mg/kg i.p. daily for five consecutive days from postnatal day (P) 6), S-100B-positive cells and anxiety level were markedly increased, while the GFAP-positive cells and PA learning were notably attenuated. The trend of diminished GFAP-immunopositive cells and elevated S100B-immunostained cells in the PFC was reversed in the SCH-like rats by exposure of animals to EE, commencing from birth up to the time of experiments on P28-85. Additionally, EE exhibited an ameliorating effect on the behavioral abnormalities evoked by MK-801. Overall, present findings support that improper astrocyte functioning and behavioral changes, reminiscent of the many facets of SCH, occur consequential to repetitive administration of MK-801 and that raising rat pups in an EE mitigates these alterations.

Gender Differences in the Neurobiology of Anxiety: Focus on Adult Hippocampal Neurogenesis

Although the literature reports a higher incidence of anxiety disorders in women, the majority of basic research has focused on male rodents, thus resulting in a lack of knowledge on the neurobiology of anxiety in females. Bridging this gap is crucial for the design of effective translational interventions in women. One of the key brain mechanisms likely to regulate anxious behavior is adult hippocampal neurogenesis (AHN). This review paper aims to discuss the evidence on the differences between male and female rodents with regard to anxiety-related behavior and physiology, with a special focus on AHN. The differences between male and female physiologies are greatly influenced by hormonal differences. Gonadal hormones and their fluctuations during the estrous cycle have often been identified as agents responsible for sexual dimorphism in behavior and AHN. During sexual maturity, hormone levels fluctuate cyclically in females more than in males, increasing the stress response and the susceptibility to anxiety. It is therefore of great importance that future research investigates anxiety and other neurophysiological aspects in the female model, so that results can be more accurately applicable to the female population.