Comparing the effects of progressive and mild intensity treadmill running protocols on neuroprotection of parkinsonian rats

Therapeutic Mechanisms of Exercise in Parkinson's Disease

Despite being the second-most common neurodegenerative disease, the etiology of Parkinson's disease (PD) remains uncertain with current knowledge suggestive of multiple risk factors. Furthermore, curative treatment does not yet exist, and treatment is primarily symptomatic in nature. For this reason, supportive therapies such as exercise are a crucial tool in PD management. It is useful to better understand how exercise affects the brain and body in the context of PD to guide clinical decision-making and determine the optimal exercise intensity and modality for PD patients. This review outlines the various mechanisms by which exercise can be beneficial as a therapeutic option in PD.

Intervention strategies for Parkinson's disease: the role of exercise and mitochondria

Parkinson's disease (PD), a progressive neurodegenerative disorder with complex pathogenic mechanisms, exhibiting rising prevalence alongside global population aging. Its pathological hallmarks include substantial loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms (e.g., bradykinesia, rigidity) and non-motor manifestations (e.g., cognitive impairment, sleep disorders). Accumulating evidence underscores mitochondrial dysfunction-encompassing reactive oxygen species (ROS) overproduction, defective mitophagy, and impaired biogenesis-as an important contributor to PD pathogenesis. Exercise, endorsed by leading medical and sports authorities as a non-pharmacological therapeutic strategy. While mitochondrial dysfunction impairs cellular energetics in PD patients, exercise can re-establish mitochondrial homeostasis through multiple pathways: stimulating neuroprotective exerkines, regulating mitochondrial ROS balance, modulating mitochondrial biogenesis and mitophagy, and enhancing brain-derived neurotrophic factor production. Many studies demonstrate that aerobic, resistance, and mind-body exercises demonstrably improve gait stability, postural control, and cognitive function in PD patients. However, standardized exercise prescriptions for PD prevention and treatment remain underutilized in clinical practice. This review synthesizes mitochondrial pathophysiology in PD progression, exercise-mediated regulatory mechanisms, and evidence-based exercise protocols, proposing accessible exercise regimens to support PD management. By integrating molecular insights with practical strategies, this work provides foundational evidence for utilizing exercise as a non-medical intervention against PD.

Effects of exercise training on nigrostriatal neuroprotection in Parkinson's disease: a systematic review

Introduction

Parkinson's disease (PD) is characterized by progressive neurodegeneration within the nigrostriatum, leading to motor dysfunction. This systematic review aimed to summarize the effects of various exercise training regimens on protein or gene expression within the nigrostriatum and their role in neuroprotection and motor function improvement in animal models of Parkinson's disease (PD).

Methods

PubMed, EMBASE, and Web of Science were searched up to June 2024 and included sixteen studies that adhere to PRISMA guidelines and CAMARADES checklist scores ranging from 4 to 6 out of 10. Various exercise training regimens, administered 5 days per week for 6.5 weeks, were applied to MPTP, 6-OHDA, and PFF-α-synuclein-induced PD animal models.

Results

Exercise training was found to downregulate the inflammatory pathway by attenuating α-synuclein aggregation, inhibiting the TLR/MyD88/IκBα signaling cascade and NF-κB phosphorylation, and decreasing pro-inflammatory cytokines IL-1β and TNF-α while increasing anti-inflammatory cytokines IL-10 and TGF-β within the nigrostriatum. It also inhibited the ASC and NLRP3 inflammasome complex and reduced the BAX/ Bcl-2 ratio and caspase-1/3 proteins, thereby decreasing neuronal apoptosis in the nigrostriatum. Exercise training elevated the expression of Pro-BDNF, BDNF, GDNF, TrkB, and Erk1/2, providing neurotrophic support to dopaminergic neurons. Furthermore, it upregulated the dopaminergic signaling pathway by increasing the expression of TH, DAT, PSD-95, and synaptophysin in the nigrostriatum.

Discussion

The findings suggested that exercise training downregulated inflammatory and apoptotic pathways while upregulated BDNF/GDNF pathways and dopaminergic signaling within the nigrostriatum. These molecular changes contributed to neuroprotection, reduced dopaminergic neuron loss, and improved motor function in PD animal models.

Systematic review registration

CRD42024484537 https://www.crd.york.ac.uk/prospero/#recordDetails.

Lactate/Hydroxycarboxylic Acid Receptor 1 in Alzheimer's Disease: Mechanisms and Therapeutic Implications-Exercise Perspective

Lactate has a novel function different from previously known functions despite its traditional association with hypoxia in skeletal muscle. It plays various direct and indirect physiological functions. It is a vital energy source within the central nervous system (CNS) and a signal transmitter regulating crucial processes, such as angiogenesis and inflammation. Activating lactate and its associated receptors elicits effects like synaptic plasticity and angiogenesis alterations. These effects can significantly influence the astrocyte-neuron lactate shuttle, potentially impacting cognitive performance. Decreased cognitive function relates to different neurodegenerative conditions, including Alzheimer's disease (AD), ischemic brain injury, and frontotemporal dementia. Therefore, lactic acid has significant potential for treating neurodegenerative disorders. Exercise is a method that induces the production of lactic acid, which is similar to the effect of lactate injections. It is a harmless and natural way to achieve comparable results. Animal experiments demonstrate that high-intensity intermittent exercise can increase vascular endothelial growth factor (VEGF) levels, thus promoting angiogenesis. In vivo, lactate receptor-hydroxycarboxylic acid receptor 1 (HCAR1) activation can occur by various stimuli, including variations in ion concentrations, cyclic adenosine monophosphate (cAMP) level elevations, and fluctuations in the availability of energy substrates. While several articles have been published on the benefits of physical activity on developing Alzheimer's disease in the CNS, could lactic acid act as a bridge? Understanding how HCAR1 responds to these signals and initiates associated pathways remains incomplete. This review comprehensively analyzes lactate-induced signaling pathways, investigating their influence on neuroinflammation, neurodegeneration, and cognitive decline. Consequently, this study describes the unique role of lactate in the progression of Alzheimer's disease.

High intensity interval training exercise increases dopamine D2 levels and modulates brain dopamine signaling

Background

Previous research has outlined the health benefits of exercise including its therapeutic potential for substance use disorders (SUD). These data have already been utilized and it is now common to find exercise as part of SUD treatment and relapse prevention programs. However, we need to better understand different exercise regimens and determine which would be the most beneficial for SUDs. Recently, high intensity interval training (HIIT) has gained attention in comparison with aerobic and resistance exercise. Little is known regarding the neurobiological mechanisms of HIIT, including its effects on dopamine signaling and receptor levels in the brain. The present study examined the effects of chronic HIIT exercise on dopamine signaling as measured by dopamine type 1-like receptor (D1R)-like, dopamine type 2-like receptor (D2R)-like, and tyrosine hydroxylase (TH) quantification in the brains of male and female rats as measured by [3H] SCH 23390 and [3H] spiperone autoradiography, and TH-immunoreactive optical density values.

Methods

Rats were separated in two groups: sedentary and HIIT exercise. Exercise was on a treadmill for 30 min daily (10 3 min cycles) for six weeks with progressive speed increased up to 0.8 mph (21.5 m/min).

Results

Results showed for D2R-like binding, a significant effect across the ventral caudate putamen (V CPU) between sexes, such that mean D2R-like binding was 14% greater for males than females. In the nucleus accumbens shell (Nac Shell), the HIIT Exercise rats showed 16% greater D2R-like binding as compared to the sedentary rats. No significant effects of HIIT exercise were found across groups for brain D1R-like binding levels or TH expression.

Conclusion

These results suggest that HIIT exercise can modulate dopamine signaling by way of increased D2R. These findings support the premise that HIIT exercise plays an important role in dopamine signaling and, may provide a potential mechanism for how HIIT exercise can impact the brain and behavior.

CDNF and MANF in the brain dopamine system and their potential as treatment for Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by gradual loss of midbrain dopamine neurons, leading to impaired motor function. Preclinical studies have indicated cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) to be potential therapeutic molecules for the treatment of PD. CDNF was proven to be safe and well tolerated when tested in Phase I-II clinical trials in PD patients. Neuroprotective and neurorestorative effects of CDNF and MANF were demonstrated in animal models of PD, where they promoted the survival of dopamine neurons and improved motor function. However, biological roles of endogenous CDNF and MANF proteins in the midbrain dopamine system have been less clear. In addition to extracellular trophic activities, CDNF/MANF proteins function intracellularly in the endoplasmic reticulum (ER), where they modulate protein homeostasis and protect cells against ER stress by regulating the unfolded protein response (UPR). Here, our aim is to give an overview of the biology of endogenous CDNF and MANF in the brain dopamine system. We will discuss recent studies on CDNF and MANF knockout animal models, and effects of CDNF and MANF in preclinical models of PD. To elucidate possible roles of CDNF and MANF in human biology, we will review CDNF and MANF tissue expression patterns and regulation of CDNF/MANF levels in human diseases. Finally, we will discuss novel findings related to the molecular mechanism of CDNF and MANF action in ER stress, UPR, and inflammation, all of which are mechanisms potentially involved in the pathophysiology of PD.

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

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

Validity of mHealth devices for counting steps in individuals with Parkinson's disease

BACKGROUND

Step quantification is a good way to characterize the mobility and functional status of individuals with some functional disorder. Therefore, a validation study may lead to the feasibility of devices to stimulate an increase in the number of steps and physical activity level of individuals with Parkinson's Disease (PD).

AIM

To investigate the validity of mHealth devices to estimate the number of steps in individuals with PD and compare the estimate with a standard criterion measure.

METHOD

An observational study in a university laboratory with 34 individuals with idiopathic PD. The number of steps was measured using mHealth devices (Google Fit, Health, STEPZ, Pacer, and Fitbit INC®), and compared against a criterionstandard measure during the Two-Minute Walk Test using habitual speed.

RESULTS

Our sample was 82% men with a Hoehn and Yahr mean of 2.3 ± 1.3 and mean walking speed of 1.2 ± 0.2 m/s. Positive and statistically significant associations were found between Google Fit (r = 0.92; p < 0.01), STEPZ (r = 0.91; p < 0.01), Pacer (r = 0.77; p < 0.01), Health (r = 0.54; p < 0.01), and Fitbit Inc® (r = 0.82; p < 0.01) with the criterion-standard measure.

CONCLUSIONS

GoogleFit, STEPZ, Fitbit Inc.®, Pacer, and Health are valid instruments to measure the number of steps over a given period of time with moderate to high correlation with the criterion-standard in individuals with PD. This result shows that technology such as smartphone applications and activity monitor can be used to assess the number of steps in individuals with PD, and allows the possibility of using this technology for assessment and intervention purposes.

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 increases the production of tyrosine hydroxylase and CDNF in the spinal cord of a Parkinson's disease mouse model

Previous research advocates that exercise is a non-pharmacological therapy for Parkinson's disease (PD). However, few studies have investigated the effects of exercise on central nervous system structures other than the nigrostriatal pathway by using PD animal models. This study investigated the effects of exercise on tyrosine hydroxylase (TH)- and cerebral dopamine neurotrophic factor (CDNF)-containing spinal-cord neurons. Male Swiss mice were divided into 4 groups: sedentary control (SEDCONT), exercise control (EXERCONT), sedentary Parkinson (SEDPD), and exercise Parkinson (EXERPD). The PD groups were submitted to a surgical procedure for stereotaxic bilateral injection of 6-hydroxydopamine into the striatum. TH- and CDNF-containing spinal-cord neurons were evaluated in all groups, using immunohistochemistry and western-blotting. TH content in the ventral horn differed notably between the SEDPD and EXERPD groups. CDNF content was highest in the EXERPD group. SEDPD and EXERPD groups differed the most, as shown by immunohistochemistry and western-blotting. The EXERPD group showed the most intense labeling in immunohistochemistry compared to the SEDCONT and EXERCONT groups. Therefore, we showed here that exercise increased the content of both TH and CDNF in the spinal-cord neurons of a bilateral PD mouse model. We may assume that the spinal cord is affected in a PD model, and therefore this central nervous system region deserves more attention from researchers dealing with PD.