Exercise effects on brain and behavior in healthy mice, Alzheimer's disease and Parkinson's disease model-A systematic review and meta-analysis

Comprehensive Exploration of the Neuroprotective Mechanisms of Ginkgo biloba Leaves in Treating Neurological Disorders

Neurological disorders (NDs) are diseases that seriously affect the health of individuals worldwide, potentially leading to a significant reduction in the quality of life for patients and their families. Herbal medicines have been widely used in the treatment of NDs due to their multi-target and multi-pathway features. Ginkgo biloba leaves (GBLs), one of the most popular herbal medicines in the world, have been demonstrated to present therapeutic effects on NDs. However, the pharmacological mechanisms of GBLs in the treatment of neurological disorders have not been systematically summarized. This study aimed to summarize the molecular mechanism of GBLs in treating NDs from the cell models, animal models, and clinical trials of studies. Four databases, i.e., PubMed, Google Scholar, CNKI, and Web of Science were searched using the following keywords: "Ginkgo biloba", "Ginkgo biloba extract", "Ginkgo biloba leaves", "Ginkgo biloba leaves extract", "Neurological disorders", "Neurological diseases", and "Neurodegenerative diseases". All items meeting the inclusion criteria on the treatment of NDs with GBLs were extracted and summarized. Additionally, PRISMA 2020 was performed to independently evaluate the screening methods. Out of 1385 records in the database, 52 were screened in relation to the function of GBLs in the treatment of NDs; of these 52 records, 39 were preclinical trials and 13 were clinical studies. Analysis of pharmacological studies revealed that GBLs can improve memory, cognition, behavior, and psychopathology of NDs and that the most frequently associated GBLs are depression, followed by Alzheimer's disease, stroke, Huntington's disease, and Parkinson's disease. Additionally, the clinical studies of depression, AD, and stroke are the most common, and most of the remaining ND data are available from in vitro or in vivo animal studies. Moreover, the possible mechanisms of GBLs in treating NDs are mainly through free radical scavenging, anti-oxidant activity, anti-inflammatory response, mitochondrial protection, neurotransmitter regulation, and antagonism of PAF. This is the first paper to systematically and comprehensively investigate the pharmacological effects and neuroprotective mechanisms of GBLs in the treatment of NDs thus far. All findings contribute to a better understanding of the efficacy and complexity of GBLs in treating NDs, which is of great significance for the further clinical application of this herbal medicine.

Unlocking the epigenome: Stress and exercise induced Bdnf regulation in the prefrontal cortex

Aversive caregiving in early life is a risk factor for aberrant brain and behavioral development. This outcome is related to epigenetic dysregulation of the brain-derived neurotrophic factor (Bdnf) gene. The Bdnf gene encodes for BDNF, a neurotrophin involved in early brain development, neural plasticity, learning, and memory. Recent work suggests that exercise may be neuroprotective in part by supporting BDNF protein and gene expression, making it an exciting target for therapeutic interventions. To our knowledge, exercise has never been studied as a therapeutic intervention in preclinical rodent models of caregiver maltreatment. To that end, the current study investigated the effect of an adult voluntary wheel running intervention on Bdnf methylation and expression in the prefrontal cortex of rats who experienced aversive caregiving in infancy. We employed a rodent model (Long Evans rats) wherein rat pups experienced intermittent caregiver-induced stress from postnatal days 1-7 and were given voluntary access to a running wheel (except in the control condition) from postnatal days 70-90 as a young adulthood treatment intervention. Our results indicate that maltreatment and exercise affect Bdnf gene methylation in an exon, CG site, and sex-specific manner. Here we add to a growing body of evidence of the ability for our experiences, including exercise, to permeate the brain. Keywords: Early life stress, Bdnf, exercise, prefrontal cortex.

Effect of exercise on sleep quality in Parkinson's disease: a mini review

The growing incidence of Parkinson's Disease (PD) is a major burden on the healthcare system. PD is caused by the degeneration of dopaminergic neurons and is known for its effects on motor function and sleep. Sleep is vital for maintaining proper homeostasis and clearing the brain of metabolic waste. Adequate time spent in each sleep stage can help maintain homeostatic function; however, patients with PD appear to exhibit sleep impairments. Although medications enhance the function of remaining dopaminergic neurons and reduce motor symptoms, their potential to improve sleep is still under question. Recently, research has shifted towards exercise protocols to help improve sleep in patients with PD. This review aims to provide an overview of how sleep is impaired in patients with PD, such as experiencing a reduction in time spent in slow-wave sleep, and how exercise can help restore normal sleep function. A PubMed search summarized the relevant research on the effects of aerobic and resistance exercise on sleep in patients with PD. Both high and low-intensity aerobic and resistance exercises, along with exercises related to balance and coordination, have been shown to improve some aspects of sleep. Neurochemically, sleeping leads to an increase in toxin clearance, including α-synuclein. Furthermore, exercise appears to enhance the concentration of brain-derived neurotrophic factors, which has preliminary evidence to suggest correlations to time spent in slow-wave sleep. More research is needed to further elucidate the physiological mechanism pertaining to sleep and exercise in patients with PD.

An Interaction between Brain-Derived Neurotrophic Factor and Stress-Related Glucocorticoids in the Pathophysiology of Alzheimer's Disease

Both the brain-derived neurotrophic factor (BDNF) and glucocorticoids (GCs) play multiple roles in various aspects of neurons, including cell survival and synaptic function. BDNF and its receptor TrkB are extensively expressed in neurons of the central nervous system (CNS), and the contribution of the BDNF/TrkB system to neuronal function is evident; thus, its downregulation has been considered to be involved in the pathogenesis of Alzheimer's disease (AD). GCs, stress-related molecules, and glucocorticoid receptors (GRs) are also considered to be associated with AD in addition to mental disorders such as depression. Importantly, a growing body of evidence suggests a close relationship between BDNF/TrkB-mediated signaling and the GCs/GR system in the CNS. Here, we introduce the current studies on the interaction between the neurotrophic system and stress in CNS neurons and discuss their involvement in the pathophysiology of AD.

The Counter Effect of Exercise on Cisplatin-Induced Cognitive and Proliferation Impairments

Background Cisplatin, a widely used chemotherapeutic agent, offers therapeutic benefits for cancer treatment but often leads to adverse effects on neurogenesis and oxidative stress, causing cognitive impairment. Concurrent physical activity has been proposed as a potential strategy to counteract these side effects. This study aimed to investigate the impact of physical exercise on cisplatin-induced cognitive impairment in a mouse model. Methods Adult male mice (n=45) were divided into three groups: control, cisplatin-treated (2.3 mg/kg), and exercise/cisplatin. Cisplatin was administered intraperitoneally over one month, while the exercise/cisplatin group underwent moderate-intensity exercise alongside cisplatin treatment. Spatial memory was evaluated using the novel object recognition (NOR) task, and hippocampal proliferation and oxidative stress were examined using Ki-67 and glutathione peroxidase (GPx) immunohistochemistry (IHC) staining, respectively. Statistical analyses were performed using the GraphPad Prism 4.0 software (GraphPad Software, San Diego, CA). Results The cisplatin-treated mice exhibited significantly lower preference index (PI) scores in the NOR task compared to the control (p<0.001) and exercise/cisplatin (p<0.001) groups. IHC staining revealed impaired hippocampal proliferation and increased oxidative stress in the cisplatin-treated group relative to the control and exercise/cisplatin groups. The introduction of a moderate-intensity exercise protocol appeared to mitigate the decline in hippocampal proliferation and oxidative damage induced by cisplatin. Additionally, cisplatin-treated mice experienced weight loss, while exercise attenuated this effect. Conclusion Cisplatin treatment resulted in decreased memory, hippocampal proliferation, and weight loss in mice. Concurrent moderate-intensity exercise seemed to alleviate these effects, suggesting a potential role for physical activity in ameliorating cisplatin-induced cognitive decline. This study underscores the importance of incorporating exercise as a complementary strategy to enhance cognitive outcomes in cancer patients undergoing cisplatin treatment.

Amelioration of Motor Performance and Nigrostriatal Dopamine Cell Volume Using a Novel Far-Infrared Ceramic Blanket in an A53T Alpha-Synuclein Transgenic Parkinson's Disease Mouse Model

We had attended a Parkinson's Disease (PD) patient for a non-healing wound who reported a marked decrease in his hand tremor and freezing of gait when his wound was exposed to a ceramic far-field infrared (cFIR) blanket. PD is the most frequent motor disorder and the second most frequent neurodegenerative disease after Alzheimer's Disease (AD). The tremor, rigidity, and slowness of movement associated with Parkinson's disease (PD) affect up to 10 million people throughout the world, and the major contributing factor to the pathogenesis of PD is the accumulation and propagation of pathological α-synuclein (α-Syn) and the death of dopaminergic cells in the Nigrostriatal system. Efforts to slow or stop its spreading have resulted in the development and use of dopaminergic drug replacement therapy. Unfortunately, there is a loss of about 70-80% of substantia nigral dopaminergic neurons in patients by the time they are diagnosed with PD, and various dopaminergic drugs provide only temporary relief of their motor symptoms. There are limitations in treating PD with many conventional medications, necessitating a combination of pharmaceutical and non-pharmacological therapy as an essential adjunct to better address the health and welfare of PD patients. We used male adult A53T alpha-synuclein transgenic mice exposed to a ceramic far-infrared blanket. Motor activity was assessed using the rotarod apparatus, and mouse brains were examined to quantify the fluorescence intensities of the immunostained samples. A53T alpha-synuclein transgenic mice had a significantly shorter time stay on the rotating bar than the wild-type mice (B6C3H). The rotarod performance was significantly improved in A53T alpha-synuclein transgenic mice exposed to cFIR as well as B6C3H healthy wild mice exposed to cFIR. There was a significant statistical and substantive increase in the cellular composition of the Striatum and substantia nigra of cFIR-treated mice. Improvement in motor performance is seen in PD mice and wild mice and is associated with increases in cell volume in the substantia nigra and striatum after treatment.

C-reactive protein as the biomarker of choice to monitor the effects of exercise on inflammation in Parkinson's disease

Parkinson's disease (PD), a heterogeneous disease with no disease-modifying treatments available, is the fastest growing neurological disease worldwide. Currently, physical exercise is the most promising treatment to slow disease progression, with evidence suggesting it is neuroprotective in animal models. The onset, progression, and symptom severity of PD are associated with low grade, chronic inflammation which can be quantified by measuring inflammatory biomarkers. In this perspective, we argue that C-reactive protein (CRP) should be used as the primary biomarker for monitoring inflammation and therefore disease progression and severity, particularly in studies examining the impact of an intervention on the signs and symptoms of PD. CRP is the most studied biomarker of inflammation, and it can be detected using relatively well-standardized assays with a wide range of detection, allowing for comparability across studies while generating robust data. An additional advantage of CRP is its ability to detect inflammation irrespective of its origin and specific pathways, an advantageous characteristic when the cause of inflammation remains unknown, such as PD and other chronic, heterogeneous diseases.

Interplay between Learning and Voluntary Wheel Running in Male C57BL/6NCrl Mice

Exercise is shown to improve cognitive function in various human and animal studies. Laboratory mice are often used as a model to study the effects of physical activity and running wheels provide a voluntary and non-stressful form of exercise. The aim of the study was to analyze whether the cognitive state of a mouse is related to its wheel-running behavior. Twenty-two male C57BL/6NCrl mice (9.5 weeks old) were used in the study. The cognitive function of group-housed mice (n = 5-6/group) was first analyzed in the IntelliCage system followed by individual phenotyping with the PhenoMaster with access to a voluntary running wheel. The mice were divided into three groups according to their running wheel activity: low, average, and high runners. The learning trials in the IntelliCage showed that the high-runner mice exhibited a higher error rate at the beginning of learning trials but improved their outcome and learning performance more compared to the other groups. The high-runner mice ate more compared to the other groups in the PhenoMaster analyses. There were no differences in the corticosterone levels between the groups, indicating similar stress responses. Our results demonstrate that high-runner mice exhibit enhanced learning capabilities prior to access to voluntary running wheels. In addition, our results also show that individual mice react differently when introduced to running wheels, which should be taken into consideration when choosing animals for voluntary endurance exercise studies.

A Preclinical Systematic Review and Meta-Analysis of Behavior Testing in Mice Models of Ischemic Stroke

Stroke remains one of the most important causes of death and disability. Preclinical research is a powerful tool for understanding the molecular and cellular response to stroke. However, a lack of standardization in animal evaluation does not always ensure reproducible results. In the present study, we wanted to identify the best strategy for evaluating animal behavior post-experimental stroke. As such, a meta-analysis was made, evaluating behavioral tests done on male C57BL/6 mice subjected to stroke or sham surgery. Overall, fifty-six studies were included. Our results suggest that different types of tests should be used depending on the post-stroke period one needs to analyze. In the hyper-acute, post-stroke period, the best quantifier will be animal examination scoring, as it is a fast and inexpensive way to identify differences between groups. When evaluating stoke mice in the acute phase, a mix of animal examination and motor tests that focus on movement asymmetry (foot-fault and cylinder testing) seem to have the best chance of picking up differences between groups. Complex tasks (the rotarod test and Morris water maze) should be used within the chronic phase to evaluate differences between the late-subacute and chronic phases.

Effect of exercise on cognitive function and synaptic plasticity in Alzheimer's disease models: A systematic review and meta-analysis

Introduction

Cognitive decline is a central manifestation of Alzheimer's disease (AD), and its process is inseparable from changes in synaptic plasticity. The aim of this review was to summarize and evaluate the effectiveness of exercise on cognitive function and synaptic plasticity in AD animal models.

Materials and methods

Eligible studies were searched from PubMed, MEDLINE, EMBASE, Web of Science, and Cochrane Library from April to May 2022. The risk of bias was evaluated by Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE). The Morris water maze (MWM) test and synaptic plasticity were considered outcome measures. Data were analyzed using random-effects meta-analyses using the software Stata. Heterogeneity was examined by using I2 test. Sensitivity analysis and publication bias were also assessed.

Results

A total of 20 randomized controlled studies were eligible for study inclusion. Compared with controls, exercise decreased escape latency (SMD = -0.86, 95% CI: -1.21 to -0.50, P < 0.001), increased platform crossover numbers (SMD = 1.34, 95% CI: 0.57-2.11, P = 0.001) and time in the target quadrant (SMD = 1.65, 95% CI: 0.95-2.36, P < 0.001) and the expression of PSD95 (SMD = 0.73, 95% CI: 0.25-1.21, P = 0.003) in AD animals. The results of the subgroup analysis showed that exercise before AD had a greater effect on escape latency (SMD = -0.88, 95% CI: -1.25 to -0.52, P < 0.001), platform crossover numbers (SMD = 1.71, 95% CI: 1.23-2.18, P < 0.001), time in the target quadrant (SMD = 2.03, 95% CI: 1.19-2.87, P < 0.001) and the expression of PSD95 (SMD = 0.94, 95% CI: 0.19-1.69, P = 0.014) than exercise after AD. The results of the subgroup analysis also showed that treadmill running might be an appropriate exercise type.

Conclusion

Our findings suggested that exercise had a potential effect on improving cognitive function and synaptic plasticity. It can play a better neuroprotective role before AD.

Systematic review registration

PROSPERO, identifier: CRD42022328438.

Aerobic Treadmill Exercise Upregulates Epidermal Growth Factor Levels and Improves Learning and Memory in d-galactose-Induced Aging in a Mouse Model

Previous studies have demonstrated that exercise improves cognitive function in Alzheimer's disease mice but the exact mechanism needs further studies. This research aimed to study the effects of aerobic treadmill exercise on epidermal growth factor (EGF) levels and learning and memory in d-galactose-induced aging in a mouse model. Forty male Kunming mice were analyzed in this study and randomly divided into 4 groups: control (C group), aerobic exercise (AE group), d-galactose (D-gal group), and d-galactose + aerobic exercise (D-gal + AE group). The C and AE groups received a daily mid-scapular subcutaneous injection of .9% saline for 40 days. Mice in the D-gal and D-gal + AE groups were subcutaneously injected with d-galactose (1.25 mg/kg) once daily for 40 days. The mice in the AE group and D-gal + AE group completed 40 days of aerobic treadmill exercise. Learning and memory were evaluated by step-down tests. Specifically, 24 h after the behavioral test, blood was collected and brain tissue was extracted, and superoxide dismutase (SOD) and acetylcholinesterase activities were detected. The neurons in the CA1 and CA3 regions of the hippocampus were counted by Nissl staining. The number of EGF-positive cells was observed by immunohistochemical methods. In the learning test, the reaction time in the D-gal group increased significantly (P < .05), while the error numbers in the D-gal group tended to decrease compared with AE, D-gal + AE, and C groups. In the memory test, the latency of mice in the D-gal group was lower, while the error in this group was higher than in the other groups (P < .05). The activities of SOD and acetylcholinesterase were lower in the D-gal group than in the other groups (P < .05). The number of EGF-positive cells and neurons in the hippocampal CA1 and CA3 regions in the D-gal + AE group was higher compared to those in the D-gal group (P < .05), and lower in groups with mice that were not injected with d-galactose. Aerobic treadmill exercise inhibited SOD activity, increased EGF-positive cells, and decreased neuronal death and apoptosis, thereby improving learning and memory in the mouse model of d-galactose-induced aging.

Comparison of the Effects of Constraint-Induced Movement Therapy and Unconstraint Exercise on Oxidative Stress and Limb Function-A Study on Human Patients and Rats with Cerebral Infarction

Most conventional post-stroke rehabilitation treatments do not involve imposed constraints of the unaffected limb. In contrast, Constraint-Induced Movement Therapy (CIMT) is comprised of massed task practice with the affected limb and constraint of the unaffected limb. CIMT is a promising rehabilitation technique used for motor recovery of affected limbs after stroke, but its effectiveness and mechanism are not fully understood. We compared the effects of the two exercise modes on limb function post-stroke in animal models and human subjects, and investigated whether oxidative stress response was involved in regulating the effects. We first conducted a randomized controlled trial (RCT), in which 84 subjects with cerebral infarction were assigned to dose-matched constraint-induced movement therapy (CIMT), or unconstraint exercise (UE), or conventional rehabilitation treatment. Motor functions of the limb are primary outcomes of the RCT measured using Brief Fugl-Meyer upper extremity score (FMA-UE), Ashworth score, and Barthel scale. Psychological influence of CIMT and UE was also examined using Self-Rating Depression Scale (SDS). Next, we investigated the effects of CIMT and UE in rats undergoing middle cerebral artery occlusion and reperfusion (MCAO/R). Motor function, infarct volume, and pathohistological changes were investigated by mNSS, MRI, and histological studies. The role of Keap1-Nrf2-ARE was investigated using qRT-PCR, Western blot, immunochemistry, immunofluorescence, and ELISA experiments. In RCT, patients taking CIMT had a higher score in FMA-UE, Barthel index, and SDS, and a lower score in modified Ashworth, compared to those taking UE. In rats receiving CIMT, motor function was increased, and infarct volume was decreased compared to those receiving UE. The expression of Keap1 protein and mRNA in the peri-infarct tissue was decreased, and Nrf2 and ARE protein and mRNA were increased in rats receiving CIMT compared with UE. Nrf2 agonist t-BHQ increased the benefits of CIMT. In conclusion, CIMT is more effective than UE in improving upper limb motor function, reducing muscle spasm in patients with cerebral infarction compared to UE, but patients receiving CIMT may feel depressed. Moreover, both CIMT and UE are beneficial to limb function recovery and limit the infarct expansion in MCAO/R rats, but CIMT was more effective than UE. Oxidative stress reaction has an essential role in regulating the CIMT induced benefits.

Characteristics of the Protocols Used in Electrical Pulse Stimulation of Cultured Cells for Mimicking In Vivo Exercise: A Systematic Review, Meta-Analysis, and Meta-Regression

While exercise benefits a wide spectrum of diseases and affects most tissues and organs, many aspects of its underlying mechanistic effects remain unsolved. In vitro exercise, mimicking neuronal signals leading to muscle contraction in vitro, can be a valuable tool to address this issue. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for this systematic review and meta-analysis, we searched EMBASE and PubMed (from database inception to 4 February 2022) for relevant studies assessing in vitro exercise using electrical pulse stimulation to mimic exercise. Meta-analyses of mean differences and meta-regression analyses were conducted. Of 985 reports identified, 41 were eligible for analysis. We observed variability among existing protocols of in vitro exercise and heterogeneity among protocols of the same type of exercise. Our analyses showed that AMPK, Akt, IL-6, and PGC1a levels and glucose uptake increased in stimulated compared to non-stimulated cells, following the patterns of in vivo exercise, and that these effects correlated with the duration of stimulation. We conclude that in vitro exercise follows motifs of exercise in humans, allowing biological parameters, such as the aforementioned, to be valuable tools in defining the types of in vitro exercise. It might be useful in transferring obtained knowledge to human research.

Direct and Inherited Epigenetic Changes in the Nervous System Caused by Intensive Locomotion: Possible Adaptive Significance

Abstract

This review is devoted to the analysis of works that investigated the long-term effects of species-specific forms of intensive locomotion on the cognitive functions of animals and humans, which can be transmitted to the next generation. To date, the anxiolytic and cognitive-enhancing long-term effects of intensive locomotion have been demonstrated in humans, rodents, fish, insects, mollusks, and nematodes. In rodents, changes in the central nervous system caused by intense locomotion can be transmitted through the maternal and paternal line to the descendants of the first generation. These include reduced anxiety, improved spatial learning and memory, increased levels of brain neurotrophic factor and vascular endothelial growth factor in the hippocampus and frontal cortex. The shift of the balance of histone acetylation in the hippocampus of rodents towards hyperacetylation, and the balance of DNA methylation towards demethylation manifests itself both as a direct and as a first-generation inherited effect of motor activity. The question about the mechanisms that link locomotion with an increase in the plasticity of a genome in the brain of descendants remains poorly understood, and invertebrate model organisms can be an ideal object for its study. Currently, there is a lack of a theoretical model explaining why motor activity leads to long-term improvement of some cognitive functions that can be transmitted to the next generation and why such an influence could have appeared in evolution. The answer to these questions is not only of fundamental interest, but it is necessary for predicting therapeutic and possible side effects of motor activity in humans. In this regard, the article pays special attention to the review of ideas on the evolutionary aspects of the problem. We propose our own hypothesis, according to which the activating effect of intensive locomotion on the function of the nervous system could have been formed in evolution as a preadaptation to a possible entry into a new environment.

Research trends and hotspots of exercise for Alzheimer’s disease: A bibliometric analysis

Objective

Alzheimer’s disease (AD) is a socially significant neurodegenerative disorder among the elderly worldwide. An increasing number of studies have revealed that as a non-pharmacological intervention, exercise can prevent and treat AD. However, information regarding the research status of this field remains minimal. Therefore, this study aimed to analyze trends and topics in exercise and AD research by using a bibliometric method.

Methods

We systematically searched the Web of Science Core Collection for published papers on exercise and AD. The retrieved data regarding institutions, journals, countries, authors, journal distribution, and keywords were analyzed using CiteSpace software. Meanwhile, the co-occurrence of keywords was constructed.

Results

A total of 1,104 papers were ultimately included in accordance with our specified inclusion criteria. The data showed that the number of published papers on exercise and AD is increasing each year, with papers published in 64 countries/regions and 396 academic journals. The Journal of Alzheimer’s Disease published the most papers (73 publications). Journals are concentrated in the fields of neuroscience and geriatrics gerontology. The University of Kansas and the United States are the major institution and country, respectively. The cited keywords show that oxidative stress, amyloid beta, and physical exercise are the research hotspots in recent years. After analysis, the neuroprotective effect of exercise was identified as the development trend in this field.

Conclusions

Based on a bibliometric analysis, the number of publications on exercise and AD has been increasing rapidly, especially in the past 10 years. “Amyloid beta,” “oxidative stress,” and “exercise program” trigger the most interest among researchers in this field. The study of exercise program and mechanism of exercise in AD is still the focus of future research.

Exercise and the Brain: Lessons From Invertebrate Studies

Benefits of physical exercise for brain functions are well documented in mammals, including humans. In this review, we will summarize recent research on the effects of species-specific intense locomotion on behavior and brain functions of different invertebrates. Special emphasis is made on understanding the biological significance of these effects as well as underlying cellular and molecular mechanisms. The results obtained in three distantly related clades of protostomes, Nematodes, Molluscs and Artropods, suggest that influence of intense locomotion on the brain could have deep roots in evolution and wide adaptive significance. In C. elegans, improved learning, nerve regeneration, resistance to neurodegenerative processes were detected after physical activity; in L. stagnalis—facilitation of decision making in the novel environment, in Drosophila—increased endurance, improved sleep and feeding behavior, in G. bimaculatus—improved orientation in conspecific phonotaxis, enhanced aggressiveness, higher mating success, resistance to some disturbing stimuli. Many of these effects have previously been described in mammals as beneficial results of running, suggesting certain similarity between distantly-related species. Our hypothesis posits that the above modulation of cognitive functions results from changes in the organism’s predictive model. Intense movement is interpreted by the organism as predictive of change, in anticipation of which adjustments need to be made. Identifying the physiological and molecular mechanisms behind these adjustments is easier in experiments in invertebrates and may lead to the discovery of novel neurobiological mechanisms for regulation and correction of cognitive and emotional status.

Inflammation—Cause or consequence of late onset Alzheimer’s disease or both? A review of the evidence

Accumulating evidence suggests that inflammation is involved in the development of late onset Alzheimer’s disease (LOAD). However, it is not clear whether inflammation is a cause or consequence, or both. The aim of this paper is to review the relationship between inflammation and LOAD. We also review the effect of anti-inflammation on the risk of LOAD to further elucidate the relationship between inflammation and LOAD.

Can exercise shape your brain? A review of aerobic exercise effects on cognitive function and neuro-physiological underpinning mechanisms

It is widely accepted that physical exercise can be used as a tool for the prevention and treatment of various diseases or disorders. In addition, in the recent years, exercise has also been successfully used to enhance people's cognition. There is a large amount of research that has supported the benefits of physical exercise on human cognition, both in children and adults. Among these studies, some have focused on the acute or transitory effects of exercise on cognition, while others have focused on the effects of regular physical exercise. However, the relation between exercise and cognition is complex and we still have limited knowledge about the moderators and mechanisms underlying this relation. Most of human studies have focused on the behavioral aspects of exercise-effects on cognition, while animal studies have deepened in its possible neuro-physiological mechanisms. Even so, thanks to advances in neuroimaging techniques, there is a growing body of evidence that provides valuable information regarding these mechanisms in the human population. This review aims to analyze the effects of regular and acute aerobic exercise on cognition. The exercise-cognition relationship will be reviewed both from the behavioral perspective and from the neurophysiological mechanisms. The effects of exercise on animals, adult humans, and infant humans will be analyzed separately. Finally, physical exercise intervention programs aiming to increase cognitive performance in scholar and workplace environments will be reviewed.

Metabolic engineering in food crops to enhance ascorbic acid production: crop biofortification perspectives for human health

Ascorbic acid (AsA) also known as vitamin C is considered as an essential micronutrient in the diet of humans. The human body is unable to synthesize AsA, thus solely dependent on exogenous sources to accomplish the nutritional requirement. AsA plays a crucial role in different physiological aspects of human health like bone formation, iron absorption, maintenance and development of connective tissues, conversion of cholesterol to bile acid and production of serotonin. It carries antioxidant properties and is involved in curing various clinical disorders such as scurvy, viral infection, neurodegenerative diseases, cardiovascular diseases, anemia, and diabetes. It also plays a significant role in COVID-19 prevention and recovery by improving the oxygen index and enhancing the production of natural killer cells and T-lymphocytes. In plants, AsA plays important role in floral induction, seed germination, senescence, ROS regulation and photosynthesis. AsA is an essential counterpart of the antioxidant system and helps to defend the plants against abiotic and biotic stresses. Surprisingly, the deficiencies of AsA are spreading in both developed and developing countries. The amount of AsA in the major food crops such as wheat, rice, maize, and other raw natural plant foods is inadequate to fulfill its dietary requirements. Hence, the biofortification of AsA in staple crops would be feasible and cost-effective means of delivering AsA to populations that may have limited access to diverse diets and other interventions. In this review, we endeavor to provide information on the role of AsA in plants and human health, and also perused various biotechnological and agronomical approaches for elevating AsA content in food crops.

Changes in Hippocampus and Amygdala Volume with Hypoxic Stress Related to Cardiorespiratory Fitness under a High-Altitude Environment

The morphology of the hippocampus and amygdala can be significantly affected by a long-term hypoxia-induced inflammatory response. Cardiorespiratory fitness (CRF) has a significant effect on the neuroplasticity of the hippocampus and amygdala by countering inflammation. However, the role of CRF is still largely unclear at high altitudes. Here, we investigated brain limbic volumes in participants who had experienced long-term hypoxia exposure in Tibet (3680 m), utilizing high-resolution structural images to allow the segmentation of the hippocampus and amygdala into their constituent substructures. We recruited a total of 48 participants (48 males; aged = 20.92 ± 1.03 years) to undergo a structural 3T MRI, and the levels of maximal oxygen uptake (VO_2max) were measured using a cardiorespiratory function test. Inflammatory biomarkers were also collected. The participants were divided into two groups according to the levels of median VO_2max, and the analysis showed that the morphological indexes of subfields of the hippocampus and amygdala of the lower CRF group were decreased when compared with the higher CRF group. Furthermore, the multiple linear regression analysis showed that there was a higher association with inflammatory factors in the lower CRF group than that in the higher CRF group. This study suggested a significant association of CRF with hippocampus and amygdala volume, which may be related to hypoxic stress in high-altitude environments. A better CRF reduced physiological stress and a decrease in the inflammatory response was observed, which may be related to the increased oxygen transport capacity of the body.

Brain-derived neurotrophic factor in Alzheimer's disease and its pharmaceutical potential

Synaptic abnormalities are a cardinal feature of Alzheimer's disease (AD) that are known to arise as the disease progresses. A growing body of evidence suggests that pathological alterations to neuronal circuits and synapses may provide a mechanistic link between amyloid β (Aβ) and tau pathology and thus may serve as an obligatory relay of the cognitive impairment in AD. Brain-derived neurotrophic factors (BDNFs) play an important role in maintaining synaptic plasticity in learning and memory. Considering AD as a synaptic disorder, BDNF has attracted increasing attention as a potential diagnostic biomarker and a therapeutical molecule for AD. Although depletion of BDNF has been linked with Aβ accumulation, tau phosphorylation, neuroinflammation and neuronal apoptosis, the exact mechanisms underlying the effect of impaired BDNF signaling on AD are still unknown. Here, we present an overview of how BDNF genomic structure is connected to factors that regulate BDNF signaling. We then discuss the role of BDNF in AD and the potential of BDNF-targeting therapeutics for AD.

The effect of exercise on early sensorimotor performance alterations in the 3xTg-AD model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by a progressive decline in cognitive function; however, recent evidence suggests that non-cognitive sensorimotor and psychomotor symptoms accompany early stages of the disease in humans and AD models. Although exercise is emerging as an important therapeutic to combat AD progression, little is known about the effect of exercise on sensorimotor domain functions. The purpose of this study was to determine if early sensorimotor symptoms accompany deficits in Morris water maze (MWM) performance in the 3xTg-AD model, and investigate if exercise could protect against early behavioral decline. 3xTg-AD and wild-type (WT) control mice were subjected to 12 weeks of moderate intensity wheel running or remained sedentary. At 6 months of age, animals underwent a series of sensorimotor and MWM testing. 3xTg-AD mice displayed deficits in sensorimotor function (beam traversal, spontaneous activity, and adhesive removal) and MWM performance. Interestingly, 3xTg-AD animals exhibited increased freezing and unusual shaking/tremoring behaviors not displayed by WT controls. Exercise improved beam traversal, adhesive removal, and reduced the unusual motor-related behaviors in 3xTg-AD mice. Our study shows that sensorimotor symptoms coincide with deficits in MWM performance, and suggest that exercise may mitigate deficits associated with early disease in 3xTg-AD mice.

Exercise plasma boosts memory and dampens brain inflammation via clusterin

Physical exercise is generally beneficial to all aspects of human and animal health, slowing cognitive ageing and neurodegeneration¹. The cognitive benefits of physical exercise are tied to an increased plasticity and reduced inflammation within the hippocampus^2-4, yet little is known about the factors and mechanisms that mediate these effects. Here we show that 'runner plasma', collected from voluntarily running mice and infused into sedentary mice, reduces baseline neuroinflammatory gene expression and experimentally induced brain inflammation. Plasma proteomic analysis revealed a concerted increase in complement cascade inhibitors including clusterin (CLU). Intravenously injected CLU binds to brain endothelial cells and reduces neuroinflammatory gene expression in a mouse model of acute brain inflammation and a mouse model of Alzheimer's disease. Patients with cognitive impairment who participated in structured exercise for 6 months had higher plasma levels of CLU. These findings demonstrate the existence of anti-inflammatory exercise factors that are transferrable, target the cerebrovasculature and benefit the brain, and are present in humans who engage in exercise.

Mechanistic Effects of Aerobic Exercise in Alzheimer's Disease: Imaging Findings From the Pilot FIT-AD Trial

Despite strong evidence from animal models of Alzheimer's disease (AD) supporting aerobic exercise as a disease-modifying treatment for AD, human mechanistic studies are limited with mixed findings. The objective of this pilot randomized controlled trial was to examine the effects of 6-month aerobic exercise on hippocampal volume, temporal meta-regions of interest (ROI) cortical thickness, white matter hyperintensity (WMH) volume, and network failure quotient (NFQ), measured with MRI, in community-dwelling older adults with AD dementia. Additionally, the relationships between 6- and 12-month changes in MRI biomarkers and the AD Assessment Scale-Cognition (ADAS-Cog) were examined. Sixty participants were randomized, but one was excluded because baseline MRI failed quality control: 38 randomized to cycling and 21 to stretching. The intervention was moderate-intensity cycling for 20–50 mins, three times a week for 6 months. Control was low-intensity stretching. The study outcomes include hippocampal volume, temporal meta-ROI cortical thickness, WMH volume, and NFQ. Outcomes were measured at baseline, 6 months, and 12 months. The sample averaged 77.3 ± 6.3 years old with 15.6 ± 2.9 years of education and 53% men. Both groups experienced significant declines over 6 months in hippocampal volume (2.64% in cycling vs. 2.89% in stretching) and temporal meta-ROI cortical thickness (0.94 vs. 1.54%), and over 12 months in hippocampal volume (4.47 vs. 3.84%) and temporal meta-ROI cortical thickness (2.27 vs. 1.79%). These declines did not differ between groups. WMH volume increased significantly with the cycling group increasing less (10.9%) than stretching (24.5%) over 6 months (f = 4.47, p = 0.04) and over 12 months (12.1 vs. 27.6%, f = 5.88, p = 0.02). NFQ did not change significantly over time. Pairwise correlational analyses showed a significant negative correlation between 6-month changes in hippocampal volume and ADAS-Cog (r = −0.34, p < 0.05). To conclude, aerobic exercise may reduce the decline in hippocampal volume and temporal meta-ROI cortical thickness during the intervention period, but the effect sizes are likely to be very small and dose-dependent and reverse once the intervention stops. Aerobic exercise is effective on slowing down WMH progression but has no effect on NFQ. Hippocampal atrophy was associated with cognitive decline during the intervention period.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT01954550.

A novel knockout mouse model of the noncoding antisense Brain-Derived Neurotrophic Factor (Bdnf) gene displays increased endogenous Bdnf protein and improved memory function following exercise

Brain-derived neurotrophic factor (Bdnf) expression is tightly controlled at the transcriptional and post-transcriptional levels. Previously, we showed that inhibition of noncoding Bdnf antisense (Bdnf-AS) RNA upregulates Bdnf protein. Here, we generated a Bdnf-antisense knockout (Bdnf-AS KO) mouse model by deleting 6 kilobases upstream of Bdnf-AS. After verifying suppression of Bdnf-AS, baseline behavioral tests indicated no significant difference in knockout and wild type mice, except for enhanced cognitive function in the knockout mice in the Y-maze. Following acute involuntary exercise, Bdnf-AS KO mice were re-assessed and a significant increase in Bdnf mRNA and protein were observed. Following long-term involuntary exercise, we observed a significant increase in nonspatial and spatial memory in novel object recognition and Barnes maze tests in young and aged Bdnf-AS KO mice. Our data provides evidence for the beneficial effects of endogenous Bdnf upregulation and the synergistic effect of Bdnf-AS knockout on exercise and memory retention.

Physical exercise increases peripheral brain-derived neurotrophic factors in patients with cognitive impairment: A meta-analysis

BACKGROUND

Physical exercise can improve cognitive dysfunction. Its specific mechanism remains unknown. Recent studies have indicated that elevating or peripherally overexpressing brain-derived neurotrophic factors (BDNF) improve cognitive impairment.

OBJECTIVE

This meta-analysis aimed to investigate whether physical exercise improves cognitive performance in patients with cognitive dysfunction, such as mild cognitive impairment (MCI) or Alzheimer's disease (AD), by increasing peripheral BDNF.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were searched up to June 2020 for studies that assayed the changes in peripheral BDNF levels in MCI and AD patients after exercise training.

RESULTS

Peripheral BDNF levels were significantly elevated after a single exercise session (SMD = 0.469, 95% CI: 0.150-0.787, P = 0.004) or regular exercise interventions (SMD = 0.418, 95% CI: 0.105-0.731, P = 0.009). Subgroup analysis showed that only regular aerobic exercise interventions (SMD = 0.543, 95% CI: 0.038-1.049, P = 0.035) and intervention duration of 16 weeks or greater (SMD = 0.443, 95% CI: 0.154 -0.733, P = 0.003) significantly increased peripheral BDNF levels. Only plasma BDNF levels (SMD = 0.365, 95% CI:0.066-0.664, P = 0.017) were significantly increased after exercise interventions.

CONCLUSIONS

Acute and chronic physical exercises may improve cognitive impairment by increasing peripheral BDNF levels. Aerobic exercises and a longer duration of exercising increased BDNF levels. These findings also suggest that BDNF may be a suitable biomarker for evaluating the effect of exercise in patients with cognitive impairment, such as AD or MCI.

Role of irisin in effects of chronic exercise on muscle and bone in ovariectomized mice

INTRODUCTION

Exercise is beneficial for the prevention and treatment of osteoporosis. Skeletal muscle affects other tissues via myokines, the release of which is regulated by acute exercise. However, the effects of chronic exercise on myokines linking muscle to bone have not been fully elucidated. Therefore, we investigated the effects of chronic exercise on bone and myokines using ovariectomized (OVX) mice.

MATERIALS AND METHODS

Treadmill exercise with moderate intensity was performed for 8 weeks after OVX or sham surgery. We measured bone mineral density (BMD) at the femurs and tibias of mice by quantitative computed tomography and myokine mRNA levels in the gastrocnemius and soleus muscles.

RESULTS

Treadmill exercise ameliorated decreases in trabecular and cortical BMD in the femurs of OVX mice. Irisin is a proteolytic product of fibronectin type III domain-containing 5 (Fndc5). Among the myokines examined, treadmill exercise increased irisin protein and Fndc5 mRNA levels in the gastrocnemius and soleus muscles of sham and OVX mice. Treadmill exercise increased peroxisome proliferator-activated receptor γ coactivator-1α mRNA levels in the gastrocnemius muscles of mice. Fndc5 mRNA levels in the gastrocnemius muscles positively correlated with trabecular BMD, but not with cortical BMD, at the femurs and tibias of mice in simple regression analyses.

CONCLUSIONS

We demonstrated that chronic exercise elevated irisin expression in the gastrocnemius and soleus muscles of estrogen-deficient mice. Irisin might be related to increases in trabecular BMD in mice; however, further studies are needed to clarify the involvement of irisin in the effects of chronic exercise on muscle/bone interactions.

Physical Exercise-Induced Myokines in Neurodegenerative Diseases

Neurodegenerative diseases (NDs), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS), are disorders characterized by progressive degeneration of the nervous system. Currently, there is no disease-modifying treatments for most NDs. Meanwhile, numerous studies conducted on human and animal models over the past decades have showed that exercises had beneficial effects on NDs. Inter-tissue communication by myokine, a peptide produced and secreted by skeletal muscles during exercise, is thought to be an important underlying mechanism for the advantages. Here, we reviewed studies about the effects of myokines regulated by exercise on NDs and their mechanisms. Myokines could exert beneficial effects on NDs through a variety of regulatory mechanisms, including cell survival, neurogenesis, neuroinflammation, proteostasis, oxidative stress, and protein modification. Studies on exercise-induced myokines are expected to provide a novel strategy for treating NDs, for which there are no adequate treatments nowadays. To date, only a few myokines have been investigated for their effects on NDs and studies on mechanisms involved in them are in their infancy. Therefore, future studies are needed to discover more myokines and test their effects on NDs.

Study on Mechanism of Ginkgo biloba L. Leaves for the Treatment of Neurodegenerative Diseases Based on Network Pharmacology

Ginkgo biloba L. leaves (GBLs), as widely used plant extract sources, significantly improve cognitive, learning and memory function in patients with dementia. However, few studies have been conducted on the specific mechanism of Neurodegenerative diseases (NDs). In this study, network pharmacology was employed to elucidate potential mechanism of GBLs in the treatment of NDs. Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) was used to obtain the chemical components in accordance with the screening principles of oral availability and drug-like property. Potential targets of GBLs were integrated with disease targets, and intersection targets were exactly the potential action targets of GBLs for treating NDs; these key targets were enriched and analyzed by the protein protein interaction (PPI) analysis and molecular docking verification. Key genes were ultimately used to find the biological pathway and explain the therapeutic mechanism by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Twenty-seven active components of GBLs may affect biological processes such as oxidative reactions and activate transcription factor activities. These components may also affect 120 metabolic pathways, such as the PI3K/AKT pathway, by regulating 147 targets, including AKT1, ALB, HSP90AA1, PTGS2, MMP9, EGFR and APP. By using the software iGEMDOCK, the main target proteins were found to bind well to the main active components of GBLs. GBLs have the characteristics of multi-component and multi-target synergistic effect on the treatment of NDs, which preliminarily predicted its possible molecular mechanism of action, and provided the basis for the follow-up study.

Impact of interval training with probiotic (L. plantarum / Bifidobacterium bifidum) on passive avoidance test, ChAT and BDNF in the hippocampus of rats with Alzheimer's disease

It has been suggested that gut microbiota dysbiosis can lead to Alzheimer's disease (AD), inducing the production of many AD-related pre-inflammatory cytokines. On the other hand, daily probiotic administration and regular exercise training are assumed to improve clinical AD-related symptoms. To take this line of research further, this study was aimed at investigating the impact of moderate-intensity interval training (MIIT) with a combined administration of Lactobacillus plantarum and Bifidobacterium bifidum (probiotic, BROB) on the passive avoidance test (Shuttle Box), choline acetyltransferase (ChAT) and the brain derived neurotrophic factor (BDNF) in the hippocampus of a rat model of AD. Forty male Wistar rats (280 ± 20 g) were divided into five groups (n = 8 in each) of control, amyloid beta peptide (Aβ), Aβ + MIIT (AD rats undergoing MIIT), Aβ + PROB (AD rats fed Lactobacillus plantarum and Bifidobacterium bifidum), and Aβ + MIIT + PROB (AD rats receiving both treatments). AD was induced by the intra-cerebroventricular injection of Aβ1-42 peptide. MIIT was performed on rodent treadmill for 8 weeks (5 days per week). The probiotic was also fed daily to the related groups for 8 weeks. BDNF and ChAT in the hippocampus were measured by real time PCR (RT-PCR) and immunohistochemistry (IHC), respectively. Cresyl violet staining of brain tissue was performed to evaluate the dead cells. Results of tissue staining showed that the induction of the Alzheimer's led to the destruction of hippocampal cells and induced neurodegeneration (p = 0.001). Results of the shuttle box test showed that short-term memory was improved in the Aβ + MIIT + PROB group compared to the Aβ group, while death cells (dark cells) were decreased in all the other three groups (MIIT, BROB, and Aβ + MIIT + PROB). Levels of ChAT as well as the BDNF mRNA in the Aβ + MIIT + PROB group showed a significant increase compared to the Aβ group. In conclusion, it seems that the use of the combined administration of Lactobacillus plantarum and Bifidobacterium bifidum with interval aerobic exercise can have neuroprotective effects on AD.

Cognitive Effects of Aerobic Exercise in Alzheimer's Disease: A Pilot Randomized Controlled Trial

BACKGROUND

Aerobic exercise has shown inconsistent cognitive effects in older adults with Alzheimer's disease (AD) dementia.

OBJECTIVE

To examine the immediate and longitudinal effects of 6-month cycling on cognition in older adults with AD dementia.

METHODS

This randomized controlled trial randomized 96 participants (64 to cycling and 32 to stretching for six months) and followed them for another six months. The intervention was supervised, moderate-intensity cycling for 20-50 minutes, 3 times a week for six months. The control was light-intensity stretching. Cognition was assessed at baseline, 3, 6, 9, and 12 months using the AD Assessment Scale-Cognition (ADAS-Cog). Discrete cognitive domains were measured using the AD Uniform Data Set battery.

RESULTS

The participants were 77.4±6.8 years old with 15.6±2.9 years of education, and 55% were male. The 6-month change in ADAS-Cog was 1.0±4.6 (cycling) and 0.1±4.1 (stretching), which were both significantly less than the natural 3.2±6.3-point increase observed naturally with disease progression. The 12-month change was 2.4±5.2 (cycling) and 2.2±5.7 (control). ADAS-Cog did not differ between groups at 6 (p = 0.386) and 12 months (p = 0.856). There were no differences in the 12-month rate of change in ADAS-Cog (0.192 versus 0.197, p = 0.967), memory (-0.012 versus -0.019, p = 0.373), executive function (-0.020 versus -0.012, p = 0.383), attention (-0.035 versus -0.033, p = 0.908), or language (-0.028 versus -0.026, p = 0.756).

CONCLUSION

Exercise may reduce decline in global cognition in older adults with mild-to-moderate AD dementia. Aerobic exercise did not show superior cognitive effects to stretching in our pilot trial, possibly due to the lack of power.

Previous flight facilitates partner finding in female crickets

In the cricket Gryllus bimaculatus, flying occurs soon after the last imaginal molt and precedes the mating behavior in natural conditions. Here, we tested the hypothesis that flying may improve subsequent behavioral performance in a novel environment in female crickets. We developed a behavioral set-up to test female cricket responsiveness to male calling song as well as their ability to locate and find the source of the song. The male song was produced by a loudspeaker hidden behind the fabric wall of a spacious square arena. Forced flight prior to the test promoted female sexual searching behavior in the novel environment. After the flight, more females reached the hidden source zone, spent more time near the source and finally more of them climbed over the wall section immediately in front of the hidden loudspeaker. At the same time, their behavior in the arena did not differ from the control group when the calling song was not delivered, suggesting that flight exerts its behavioral effects by influencing sexual motivation. Our results support the suggestion that preceding intense locomotion facilitates sexual searching behavior of females in a novel environment.

Intranasal Delivery: Effects on the Neuroimmune Axes and Treatment of Neuroinflammation

This review highlights the pre-clinical and clinical work performed to use intranasal delivery of various compounds from growth factors to stem cells to reduce neuroimmune interactions. We introduce the concept of intranasal (IN) delivery and the variations of this delivery method based on the model used (i.e., rodents, non-human primates, and humans). We summarize the literature available on IN delivery of growth factors, vitamins and metabolites, cytokines, immunosuppressants, exosomes, and lastly stem cells. We focus on the improvement of neuroimmune interactions, such as the activation of resident central nervous system (CNS) immune cells, expression or release of cytokines, and detrimental effects of signaling processes. We highlight common diseases that are linked to dysregulations in neuroimmune interactions, such as Alzheimer's disease, Parkinson's disease, stroke, multiple sclerosis, and traumatic brain injury.

Physical activity and cognitive stimulation ameliorate learning and motor deficits in a transgenic mouse model of Alzheimer's disease

Epidemiological studies suggest that physical exercise or cognitive stimulation might contribute to lower the risk of developing dementia disorders such as Alzheimer's disease (AD). Here, we used the well-established enrichment environment (EE) paradigm to study the impact of prolonged physical activity and cognitive stimulation in a mouse model of AD overexpressing only Aβ_4-42 peptides. These mice display age-dependent memory and motor deficits, in the absence of human amyloid precursor protein (APP) overexpression. We demonstrate that housing under EE conditions leads to an entire preservation of recognition and spatial memory, as well as a rescue of motor deficits in this mouse model. Moreover, we find that Tg4-42^hom mice present a typical floating phenotype in the Morris water maze task that could be completely ameliorated upon long-term EE housing. Our findings are in line with epidemiological studies suggesting that physical activity and cognitive stimulation might represent efficient strategies to prevent age-related neurodegenerative disorders such as AD.

Cognitive Training as a Potential Activator of Hippocampal Neurogenesis in the Rat Model of Sporadic Alzheimer's Disease

There is a growing body of evidence that interventions like cognitive training or exercises prior to the manifestation of Alzheimer’s disease (AD) symptoms may decelerate cognitive decline. Nonetheless, evidence of prevention or a delay of dementia is still insufficient. Using OXYS rats as a suitable model of sporadic AD and Wistar rats as a control, we examined effects of cognitive training in the Morris water maze on neurogenesis in the dentate gyrus in presymptomatic (young rats) and symptomatic (adult rats) periods of development of AD signs. Four weeks after the cognitive training, we immunohistochemically estimated densities of quiescent and amplifying neuronal progenitors, neuronal-lineage cells (neuroblasts and immature and mature neurons), and astrocytes in young and adult rats, and the amyloid precursor protein and amyloid-β in adult rats. Reference memory was defective in OXYS rats. The cognitive training did not affect neuronal-lineage cells’ density in either rat strain either at the young or adult age, but activated neuronal progenitors in young rats and increased astrocyte density and downregulated amyloid-β in adult OXYS rats. Thus, to activate adult neurogenesis, cognitive training should be started before first neurodegenerative changes, whereas cognitive training accompanying amyloid-β accumulation affects only astrocytic support.