Physical Exercise Modulates L-DOPA-Regulated Molecular Pathways in the MPTP Mouse Model of Parkinson's Disease

Aerobic exercise modulates the striatal Erk/MAPK signaling pathway and improves LID in a mouse model of Parkinson's disease

OBJECTIVE

To investigate the role of the striatal extracellular signal-regulated kinase (Erk1/2) and its phosphorylation (p-Erk1/2) in aerobic training to alleviate the development of the L-DOPA induced dyskinesia (LID) in PD mice.

METHODS

Forty-eight male C57BL/6 N mice were randomly divided into the 6-OHDA surgery group (6-OHDA, n=42) and the sham surgery group (Sham, n=6). A two-point injection of 6-OHDA into the right striatum was used to establish a lateralized injury PD model. PD mice were randomly divided into a PD control group (PD, n=13) and a PD exercise group (PDE, n=16), this is followed by 4 weeks of L-DOPA treatment, and PDE mice received concurrent running table training (18 m/min, 40 min/day, 5 times/week). AIM scores were performed weekly, and mice were assessed for motor function after 4 weeks using the rotarod, open field, and gait tests. Immunohistochemistry was used to test nigrostriatal TH expression, Western blot was used to determine Erk1/2 and p-Erk1/2 protein expression, and immunofluorescence double-labeling technique was used to detect Erk1/2 and p-Erk1/2 co-expression with prodynorphin (PDYN).

RESULTS

(1) All AIM scores of PD and PDE mice increased significantly (P < 0.05) with the prolongation of L-DOPA treatment. Compared with PD, all AIM scores were significantly lower in PDE mice (P < 0.05). (2) After 4 weeks, the motor function of PD mice was significantly reduced compared with Sham (P < 0.05 or P < 0.01); compared with PD, the motor function of PDE mice was significantly increased (P < 0.05). (3) Compared with Sham, the expression of Erk1/2 protein, the number of positive cells of Erk1/2 and p-Erk1/2 and the number of positive cells co-expressed with PDYN were significantly increased in PD mice (P < 0.05); compared with PD, Erk1/2 protein expression was significantly decreased in PDE mice (P < 0.05), and the number of Erk1/2 and p-Erk1/2 positive cells was significantly reduced (P < 0.05).

CONCLUSION

4 weeks of aerobic exercise can effectively alleviate the development of L-DOPA-induced dyskinesia and improve motor function in PD mice. The related mechanism may be related to the inhibition of striatal Erk/MAPK signaling pathway overactivation by aerobic exercise, but this change did not occur selectively in D1-MSNs.

Physical activity and lifestyle modifications in the treatment of neurodegenerative diseases

Neurodegenerative diseases have reached alarming numbers in the past decade. Unfortunately, clinical trials testing potential therapeutics have proven futile. In the absence of disease-modifying therapies, physical activity has emerged as the single most accessible lifestyle modification with the potential to fight off cognitive decline and neurodegeneration. In this review, we discuss findings from epidemiological, clinical, and molecular studies investigating the potential of lifestyle modifications in promoting brain health. We propose an evidence-based multidomain approach that includes physical activity, diet, cognitive training, and sleep hygiene to treat and prevent neurodegenerative diseases.

Multi-omics studies reveal ameliorating effects of physical exercise on neurodegenerative diseases

INTRODUCTION

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease, are heavy burdens to global health and economic development worldwide. Mounting evidence suggests that exercise, a type of non-invasive intervention, has a positive impact on the life quality of elderly with neurodegenerative diseases. X-omics are powerful tools for mapping global biochemical changes in disease and treatment.

METHOD

Three major databases were searched related to current studies in exercise intervention on neurodegenerative diseases using omics tools, including metabolomics, metagenomics, genomics, transcriptomics, and proteomics.

RESULT

We summarized the omics features and potential mechanisms associated with exercise and neurodegenerative diseases in the current studies. Three main mechanisms by which exercise affects neurodegenerative diseases were summed up, including adult neurogenesis, brain-derived neurotrophic factor (BDNF) signaling, and short-chain fatty acids (SCFAs) metabolism.

CONCLUSION

Overall, there is compelling evidence that exercise intervention is a feasible way of preventing the onset and alleviating the severity of neurodegenerative diseases. These studies highlight the importance of exercise as a complementary approach to the treatment and intervention of neurodegenerative diseases in addition to traditional treatments. More mechanisms on exercise interventions for neurodegenerative diseases, the specification of exercise prescriptions, and differentiated exercise programs should be explored so that they can actually be applied to the clinic.

RNA-binding protein ELAVL4/HuD ameliorates Alzheimer's disease-related molecular changes in human iPSC-derived neurons

The RNA binding protein ELAVL4/HuD regulates the translation and splicing of multiple Alzheimer's disease (AD) candidate genes. We generated ELAVL4 knockout (KO) human induced pluripotent stem cell-derived neurons to study the effect that ELAVL4 has on AD-related cellular phenotypes. ELAVL4 KO significantly increased the levels of specific APP isoforms and intracellular phosphorylated tau, molecular changes that are related to the pathological hallmarks of AD. Overexpression of ELAVL4 in wild-type neurons and rescue experiments in ELAVL4 KO cells showed opposite effects and also led to a reduction of the extracellular amyloid-beta (Aβ)42/40 ratio. All these observations were made in familial AD (fAD) and fAD-corrected neurons. To gain insight into the molecular cascades involved in neuronal ELAVL4 signaling, we conducted pathway and upstream regulator analyses of transcriptomic and proteomic data from the generated neurons. These analyses revealed that ELAVL4 affects multiple biological pathways linked to AD, including those involved in synaptic function, as well as gene expression downstream of APP and tau signaling. The analyses also suggest that ELAVL4 expression is regulated by insulin receptor-FOXO1 signaling in neurons. Taken together, ELAVL4 expression ameliorates AD-related molecular changes in neurons and affects multiple synaptic pathways, making it a promising target for novel drug development.

Light-Sensitive Lactococcus lactis for Microbe-Gut-Brain Axis Regulating via Upconversion Optogenetic Micro-Nano System

The discovery of the gut-brain axis has proven that brain functions can be affected by the gut microbiota's metabolites, so there are significant opportunities to explore new tools to regulate gut microbiota and thus work on the brain functions. Meanwhile, engineered bacteria as oral live biotherapeutic agents to regulate the host's healthy homeostasis have attracted much attention in microbial therapy. However, whether this strategy is able to remotely regulate the host's brain function in vivo has not been investigated. Here, we engineered three blue-light-responsive probiotics as oral live biotherapeutic agents. They are spatiotemporally delivered and controlled by the upconversion optogenetic micro-nano system. This micro-nano system promotes the small intestine targeting and production of the exogenous L. lactis in the intestines, which realizes precise manipulation of brain functions including anxiety behavior, Parkinson's disease, and vagal afferent. The noninvasive and real-time probiotic intervention strategy makes the communiation from the gut to the host more controllable, which will enable the potential for engineered microbes accurately and effectively regulating a host's health.

Ischemic stroke causes Parkinson's disease-like pathology and symptoms in transgenic mice overexpressing alpha-synuclein

The etiology of Parkinson's disease is poorly understood and is most commonly associated with advancing age, genetic predisposition, or environmental toxins. Epidemiological findings suggest that patients have a higher risk of developing Parkinson's disease after ischemic stroke, but this potential causality lacks mechanistic evidence. We investigated the long-term effects of ischemic stroke on pathogenesis in hemizygous TgM83 mice, which express human α-synuclein with the familial A53T mutation without developing any neuropathology or signs of neurologic disease for more than 600 days. We induced transient focal ischemia by middle cerebral artery occlusion in 2-month-old TgM83^+/- mice and monitored their behavior and health status for up to 360 days post surgery. Groups of mice were sacrificed at 14, 30, 90, 180, and 360 days after surgery for neuropathological analysis of their brains. Motor deficits first appeared 6 months after focal ischemia and worsened until 12 months afterward. Immunohistochemical analysis revealed ischemia-induced neuronal loss in the infarct region and astrogliosis and microgliosis indicative of an inflammatory response, which was most pronounced at 14 days post surgery. Infarct volume and inflammation gradually decreased in size and severity until 180 days post surgery. Surprisingly, neuronal loss and inflammation were increased again by 360 days post surgery. These changes were accompanied by a continuous increase in α-synuclein aggregation, its neuronal deposition, and a late loss of dopaminergic neurons in the substantia nigra, which we detected at 360 days post surgery. Control animals that underwent sham surgery without middle cerebral artery occlusion showed no signs of disease or neuropathology. Our results establish a mechanistic link between ischemic stroke and Parkinson's disease and provide an animal model for studying possible interventions.

The effects of treadmill exercise in animal models of Parkinson's disease: A systematic review

Parkinson's disease (PD) is a progressive disabling brain disorder. Physical exercise has been shown to alleviate the symptoms of PD and, consequently, improve patient quality of life. Exercise mechanisms involved in beneficial effects on PD have been widely investigated. This study aims to systematically review the literature on the use of treadmill exercise in PD animal models. The study was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Searches were conducted in MEDLINE, EMBASE, and ISI databases. In total, 78 studies were included. The dopaminergic system, behavior, neuroplasticity, neuroinflammation, mitochondria, and musculoskeletal systems were some of the outcomes evaluated by the selected studies. Based on the systematic review center for laboratory animal experimentation (SYRCLE) RoB tool, the methodologies revealed a high risk of bias and lack of information about study design, which needs attention for data reproducibility. This review can guide future studies that aim to fill existing gaps regarding the effects of treadmill exercise in PD animal models.

Physical Exercise Modulates Brain Physiology Through a Network of Long- and Short-Range Cellular Interactions

In the last decades, the effects of sedentary lifestyles have emerged as a critical aspect of modern society. Interestingly, recent evidence demonstrated that physical exercise plays an important role not only in maintaining peripheral health but also in the regulation of central nervous system function. Many studies have shown that physical exercise promotes the release of molecules, involved in neuronal survival, differentiation, plasticity and neurogenesis, from several peripheral organs. Thus, aerobic exercise has emerged as an intriguing tool that, on one hand, could serve as a therapeutic protocol for diseases of the nervous system, and on the other hand, could help to unravel potential molecular targets for pharmacological approaches. In the present review, we will summarize the cellular interactions that mediate the effects of physical exercise on brain health, starting from the factors released in myocytes during muscle contraction to the cellular pathways that regulate higher cognitive functions, in both health and disease.

The dysregulated Pink1- Drosophila mitochondrial proteome is partially corrected with exercise

One of the genes which has been linked to the onset of juvenile/early onset Parkinson’s disease (PD) is PINK1. There is evidence that supports the therapeutic potential of exercise in the alleviation of PD symptoms. It is possible that exercise may enhance synaptic plasticity, protect against neuro-inflammation and modulate L-Dopa regulated signalling pathways. We explored the effects of exercise on Pink1 deficient Drosophila melanogaster which undergo neurodegeneration and muscle degeneration. We used a ‘power-tower’ type exercise platform to deliver exercise activity to Pink1^- and age matched wild-type Drosophila. Mitochondrial proteomic profiles responding to exercise were obtained. Of the 516 proteins identified, 105 proteins had different levels between Pink1^- and wild-type non-exercised Drosophila. Gene ontology enrichment analysis and STRING network analysis highlighted proteins and pathways with altered expression within the mitochondrial proteome. Comparison of the Pink1^- exercised proteome to wild-type proteomes showed that exercising the Pink1^- Drosophila caused their proteomic profile to return towards wild-type levels.

Guidelines on exercise testing and prescription for patients at different stages of Parkinson's disease

BACKGROUND

Exercise is highly recommended in patients with Parkinson's disease (PD). Exercise-induced amelioration of motor, non-motor, and drug-induced symptoms are widely known. However, specific guidelines on exercise testing and prescription in PD are lacking.

OBJECTIVE

This study reviews the literature on exercise-based approaches to the management of symptoms at each stage of the disease and evaluate: (1) the most suitable clinical exercise testing; (2) training programs based on testing outcomes and PD stage; (3) the effects of exercise on antiparkinsonian drugs and to suggest the most effective exercise-medication combination.

METHODS

A systematic search was conducted using the databases MEDLINE, Google Scholar and, Cochrane Library using "Parkinson's Disease AND Physical therapy", "Training AND Parkinson", "Exercise", "Exercise AND Drug" as key words. In addition, references list from the included articles were searched and cross-checked to identify any further potentially eligible studies.

RESULTS

Of a total of 115 records retrieved, 50 (43%) were included. From these, 23 were included under the rubric "exercise testing"; 20 focused on the effectiveness of different types of exercise in PD motor-functional symptoms and neuroprotective effects, throughout disease progression, were included under the rubric "training protocol prescription"; and 7 concern the rubric "interaction between exercise and medication", although none reported consistent results.

CONCLUSIONS

Despite the lack of standardized parameters for exercise testing and prescription, all studies agree that PD patients should be encouraged to regularly train according to their severity-related limitations and their personalized treatment plan. In this manuscript, specific guidelines for tailored clinical testing and prescription are provided for each stage of PD.

Transcriptome sequencing reveals aerobic exercise training-associated lncRNAs for improving Parkinson's disease

The present study aimed to evaluate the effect of aerobic exercise training (AET) on the performance of mice with Parkinson's disease (PD) and to explore the molecular mechanism of AET-associated long noncoding RNAs (lncRNAs) in PD treatment. The results showed that the behaviors of PD mice were significantly improved after 4 weeks of AET. The substantia nigra pars compacta of PD mice showed scattered large multipolar cells and surrounding neutrophils after AET. In addition, a total of 62 differentially expressed lncRNAs (DE-lncRNAs) were identified between the AET group and the PD group, including 55 up-regulated and 7 down-regulated DE-lncRNAs in the AET group. Furthermore, the target genes of DE-lncRNAs, including LOC102633466, LOC102637865, and LOC102638670, were mainly involved in ECM-receptor interaction, the Wnt pathway and the PI3K/AKT/mTOR pathway. Quantitative real-time polymerase chain reaction showed that these three DE-lncRNAs were significantly up-regulated in the AET group than in the PD group. The lncRNA-miRNA-mRNA ceRNA network suggested that these 3 DE-lncRNAs may improve PD via the ceRNA mechanism. In conclusion, this study suggests that aerobic exercise improves motor performance of PD mice and provides a foundation for further studies on the molecular mechanism of lncRNAs in treating PD.

Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK) Enhances Activation of STAT3/NLRC4 Inflammasome Signaling Axis through PKCδ in Astrocytes: Implications for Parkinson's Disease

Astrocytic dysfunction has been implicated in Parkinson's disease (PD) pathogenesis. While the Tumor necrosis factor-like weak inducer of apoptosis (TWEAK)/Fn14 signaling axis is known to play a role in PD-like neuropathology, the molecular mechanisms that govern this process remain poorly understood. Herein, we show that TWEAK levels are elevated in PD serum compared to controls. Moreover, using both U373 human astrocyte cells and primary mouse astrocytes, we demonstrate that TWEAK induces mitochondrial oxidative stress as well as protein kinase C delta (PKCδ) and signal transducer and activator of transcription 3 (STAT3) activation, accompanied by NLRC4 inflammasome activation and upregulation and release of proinflammatory cytokines, including IL-1β, TNF-α, and IL-18. Mechanistically, TWEAK-induced PKCδ activation enhances the STAT3/NLRC4 signaling pathway and other proinflammatory mediators through a mitochondrial oxidative stress-dependent mechanism. We further show that PKCδ knockdown and mito-apocynin, a mitochondrial antioxidant, suppress TWEAK-induced proinflammatory NLRC4/STAT3 signaling and cellular oxidative stress response. Notably, we validated our in vitro findings in an MPTP mouse model of PD and in mice receiving intrastriatal administration of TWEAK. These results indicate that TWEAK is a key regulator of astroglial reactivity and illustrate a novel mechanism by which mitochondrial oxidative stress may influence dopaminergic neuronal survival in PD.

The potassium channel KCa3.1 represents a valid pharmacological target for microgliosis-induced neuronal impairment in a mouse model of Parkinson's disease

Background

Recent studies described a critical role for microglia in Parkinson’s disease (PD), where these central nerve system resident immune cells participate in the neuroinflammatory microenvironment that contributes to dopaminergic neurons loss in the substantia nigra. Understanding the phenotype switch of microgliosis in PD could help to identify the molecular mechanism which could attenuate or delay the progressive decline in motor function. KCa3.1 has been reported to regulate the “pro-inflammatory” phenotype switch of microglia in neurodegenerative pathological conditions.

Methods

We here investigated the effects of gene deletion or pharmacological blockade of KCa3.1 activity in wild-type or KCa3.1^−/− mice after treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a mouse model of PD. MPTP-induced PD mouse model was subjected to the rotarod test to evaluate the locomotor ability. Glia activation and neuron loss were measured by immunostaining. Fluo-4 AM was used to measure cytosolic Ca²⁺ level in 1-methyl-4-phenylpyridinium (MPP⁺)-induced microgliosis in vitro.

Results

We report that treatment of MPTP-induced PD mouse model with gene deletion or pharmacological blockade of KCa3.1 with senicapoc improves the locomotor ability and the tyrosine hydroxylase (TH)-positive neuron number and attenuates the microgliosis and neuroinflammation in the substantia nigra pars compacta (SNpc). KCa3.1 involves in store-operated Ca²⁺ entry-induced Ca²⁺ overload and endoplasmic reticulum stress via the protein kinase B (AKT) signaling pathway during microgliosis. Gene deletion or blockade of KCa3.1 restored AKT/mammalian target of rapamycin (mTOR) signaling both in vivo and in vitro.

Conclusions

Taken together, these results demonstrate a key role for KCa3.1 in driving a pro-inflammatory microglia phenotype in PD.

Effect of NAC treatment and physical activity on neuroinflammation in subchronic Parkinsonism; is physical activity essential?

BACKGROUND

Neuroprotective strategies are becoming relevant to slow down dopaminergic cell death and inflammatory processes related to the progressive neurodegeneration in Parkinson's disease (PD). Interestingly, among others, physical activity (PA) or anti-oxidant agents (such as N-acetyl-L-cysteine, NAC) are common therapeutic strategies. Therefore, this study aims to analyze if there is a synergistic effect of physical activity along with NAC treatment on dopaminergic degeneration and neuroinflammatory response in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism model after subchronic intoxication.

METHODS

To ascertain this possibility, 48 8-week-old male mice (C57BL/6 strain) were used. Twenty four of them were placed individually in cages where voluntary physical activity was automatically monitored during 30 days and were divided into groups: (i) control; (ii) NAC; (iii) MPTP, and (iv) MPTP+NAC. The other 24 mice were divided into the same four groups but without physical activity.

RESULTS

The data collected during the treatment period showed that there was an overall increase in the total running distance in all groups under physical activity, including Parkinsonian animals. However, the monitoring data per day showed that the activity routine by MPTP and MPTP+NAC groups was disrupted by alterations in the circardian rhythm because of MPTP intoxication. Results from post-mortem studies in the substantia nigra pars compacta (SNpc) showed significant decrease in the number of TH+ cells in all MPTP groups. Moreover, TH+ expression in the striatum was significantly decreased in all MPTP groups. Thus, PA + NAC treatment do not protect dopaminergic neurons against a subchronic intoxication of MPTP. Regarding glial response, the results obtained from microglial analysis do not show significant increase in the number of Iba-1+ cell in MPTP+NAC and MPTP+PA + NAC. In the striatum, a significant decrease is observed only in the MPTP+NAC group compared with that of the MPTP group. The microglial results are reinforced by those obtained from the analysis of astroglial response, in which a decrease in the expression of GFAP+ cells are observed in MPTP+NAC and MPTP+PA + NAC compared with MPTP groups both in the SNpc and in the striatum. Finally, from the study of the astroglial response by the co-localization of GFAP/S100b, we described some expression patterns observed based on the severity of the damage produced by the MPTP intoxication in the different treated groups.

CONCLUSIONS

These results suggest that the combination of physical activity with an anti-oxidant agent does not have a synergistic neuroprotective effect in the nigrostriatal pathway. Our results show a potential positive effect, only due to NAC treatment, on the neuroinflammatory response after subchronic MPTP intoxication. Thus, physical activity is not essential, under these conditions. However, we believe that physical activity, used for therapeutic purposes, has a beneficial long-term effect. In this line, these results open the door to design longer studies to demonstrate its promising effect as neuroprotective strategy.

Treadmill Exercise Attenuates L-DOPA-Induced Dyskinesia and Increases Striatal Levels of Glial Cell-Derived Neurotrophic Factor (GDNF) in Hemiparkinsonian Mice

Exercise can act as a disease-modifying agent in Parkinson's disease (PD), and we have previously demonstrated that voluntary exercise in running wheels during 2 weeks normalizes striatopallidal dopaminergic signaling and prevents the development of L-DOPA-induced dyskinesia (LID) in C57BL/6 mice. We now tested whether LID in Swiss albino mice could be attenuated by treadmill-controlled exercise alone or in combination with the reference antidyskinetic drug amantadine. The daily intraperitoneal (i.p.) treatment with three different doses of L-DOPA/benserazide (30/12.5, 50/25, or 70/35 mg/kg) during 3 weeks induced increasing levels of LID scores in hemiparkinsonian Swiss albino mice previously lesioned with a unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA, 10 μg). Then, we addressed the antidyskinetic effects of treadmill-controlled exercise by comparing LID, induced by L-DOPA/benserazide (50/25 mg/kg, i.p.) during 4 weeks, in sedentary and daily exercised mice. Exercise reduced LID and improved motor skills of dyskinetic mice, as indicated by decreased contralateral bias, increase in maximal load test, and latency to fall in rotarod. The antidyskinetic effect of amantadine (60 mg/kg, i.p.) was only observed in sedentary mice, indicating the absence of synergistic antidyskinetic effect of the combination of treadmill exercise plus amantadine. Finally, Western blot analysis unraveled an ability of exercise to increase the striatal immunocontent of glial cell-derived neurotrophic factor (GDNF), apart from normalizing striatal levels of tyrosine hydroxylase. These findings show that controlled treadmill exercise attenuates LID and provide the first indication that the antidyskinetic effects of treadmill exercise may involve increased striatal GDNF levels.