Treadmill exercise modifies dopamine receptor expression in the prefrontal cortex of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mouse model of Parkinson’s disease

Chlorpromazine, an Inverse Agonist of D1R-Like, Differentially Targets Voltage-Gated Calcium Channel (CaV) Subtypes in mPFC Neurons

The dopamine receptor type 1 (D1R) and the dopamine receptor type 5 (D5R), which are often grouped as D1R-like due to their sequence and signaling similarities, exhibit high levels of constitutive activity. The molecular basis for this agonist-independent activation has been well characterized through biochemical and mutagenesis in vitro studies. In this regard, it was reported that many antipsychotic drugs act as inverse agonists of D1R-like constitutive activity. On the other hand, D1R is highly expressed in the medial prefrontal cortex (mPFC), a brain area with important functions such as working memory. Here, we studied the impact of D1R-like constitutive activity and chlorpromazine (CPZ), an antipsychotic drug and D1R-like inverse agonist, on various neuronal Ca_V conductances, and we explored its effect on calcium-dependent neuronal functions in the mouse medial mPFC. Using ex vivo brain slices containing the mPFC and transfected HEK293T cells, we found that CPZ reduces Ca_V2.2 currents by occluding D1R-like constitutive activity, in agreement with a mechanism previously reported by our lab, whereas CPZ directly inhibits Ca_V1 currents in a D1R-like activity independent manner. In contrast, CPZ and D1R constitutive activity did not affect Ca_V2.1, Ca_V2.3, or Ca_V3 currents. Finally, we found that CPZ reduces excitatory postsynaptic responses in mPFC neurons. Our results contribute to understanding CPZ molecular targets in neurons and describe a novel physiological consequence of CPZ non-canonical action as a D1R-like inverse agonist in the mouse brain.

Effects of nordic walking exercise on gait, motor/non-motor symptoms, and serum brain-derived neurotrophic factor in individuals with Parkinson's disease

Objective

The primary purpose of this study was to investigate the immediate and long-term effects of Nordic Walking (NW) exercise on walking function, motor/non-motor Parkinson's Disease (PD) symptoms, and serum brain-derived neurotrophic factor (BDNF) in persons with idiopathic PD.

Methods

Twelve community-dwelling participants with mild to moderate idiopathic PD and varied degrees of gait dysfunction were recruited for this prospective, repeated measures design that examined clinical measures and BDNF levels at baseline (T0), post-intervention (T1) and 3-month follow-up (T2). Participants engaged in 6 weeks of supervised NW exercise training with individualized instruction, followed by 14 weeks of independent NW exercise with remote coaching. Outcome measurements included daily step counts, 6-Minute Walk Test (6-MinWT), 10-Meter Walk Test (10MWT), spatiotemporalparameters, Timed Up and Go Test (TUG), dual-task TUG, Revised-Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Revised-Freezing of Gait Questionnaire, MDS-Nonmotor Symptom scale (NMS), Parkinson's Fatigue Scale, and serum BDNF levels. The Friedman test with post hoc Wilcoxon sign-ranked pairwise comparisons were used to compare baseline to T1, baseline to T2, and T1 to T2 timepoints with a Benjamini-Hockberg correction applied.

Results

Statistically significant improvements found post-training and retained at 3-month follow-up included 6-MinWT, daily step count, 10mWT, MDS-UPDRS, and TUG with effect sizes of 0.57 to 1.03. Serum BDNF at T2 was significantly greater than T0 and T1. Although no statistically significant improvements were observed in the MDS-NMS, 9 of 12 participants had improved non-motor symptoms. There was good adherence, sustained independent exercise engagement, and no adverse events over the 5-month study duration.

Conclusions

This study demonstrated that NW exercise was a safe, feasible, and sustainable mode of aerobic exercise for this sample of participants with varied Parkinson's disease duration and severity. Following an individualized and progressive NW training intervention, significant improvements in walking function, daily activity level, and motor function were observed. Following the supervised NW training phase, independent three-month engagement in NW exercise was sustained with long-term retention of these clinical improvements and an increase in serum BDNF levels over this five-month NW exercise trial.

Impact

Nordic walking exercise may be a safe, feasible and sustainable mode of independent exercise for improving daily ambulatory activity, gait and motor function, and serum BDNF in individuals with mild to moderate PD with varied gait abilities.

Clinical Trials Registry ID

20-101-H.

Transcriptional Profiling Reveals Brain Region-Specific Gene Networks Regulated in Exercise in a Mouse Model of Parkinson’s Disease

Background

Exercise plays an essential role in improving motor symptoms in Parkinson’s disease (PD), but the underlying mechanism in the central nervous system remains unclear.

Methods

Motor ability was observed after 12-week treadmill exercise on a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. RNA-sequencing on four brain regions (cerebellum, cortex, substantia nigra (SN), and striatum) from control animals, MPTP-induced PD, and MPTP-induced PD model treated with exercise for 12 weeks were performed. Transcriptional networks on the four regions were further identified by an integrative network biology approach.

Results

The 12-week treadmill exercise significantly improved the motor ability of an MPTP-induced mouse model of PD. RNA-seq analysis showed SN and striatum were remarkably different among individual region’s response to exercise in the PD model. Especially, synaptic regulation pathways about axon guidance, synapse assembly, neurogenesis, synaptogenesis, transmitter transport-related pathway, and synaptic regulation genes, including Neurod2, Rtn4rl2, and Cd5, were upregulated in SN and striatum. Lastly, immunofluorescence staining revealed that exercise rescued the loss of TH+ synapses in the striatal region in PD mice, which validates the key role of synaptic regulation pathways in exercise-induced protective effects in vivo.

Conclusion

SN and striatum are important brain regions in which critical transcriptional changes, such as in synaptic regulation pathways, occur after the exercise intervention on the PD model.

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.

A Parkinson's disease patient displaying increased neuromelanin-sensitive areas in the substantia nigra after rehabilitation with tDCS: a case report

Previous studies have reported that transcranial direct current stimulation (tDCS) of the frontal polar area (FPA) ameliorated motor disability in patients with Parkinson's disease (PD). Here we report changes in neuromelanin (NM) imaging of dopaminergic neurons before and after rehabilitation combined with anodal tDCS over the FPA for 2 weeks in a PD patient. After the intervention, the patient showed clinically meaningful improvements while the NM-sensitive area in the SN increased by 18.8%. This case study is the first report of NM imaging of the SN in a PD patient who received tDCS.Abbreviations FPA: front polar area; PD: Parkinson's disease; NM: neuromelanin; DCI: DOPA decarboxylase inhibitor; STEF: simple test for evaluating hand function; TUG: timed up and go test; TMT: trail-making test; SN: substantia nigra; NM-MRI: neuromelanin magnetic resonance imaging; MCID: the minimal clinically important difference; SNpc: substantia nigra pars compacta; VTA: ventral tegmental area; LC: locus coeruleus; PFC: prefrontal cortex; M1: primary motor cortex; MDS: Movement Disorder Society; MIBG: ¹²³I-metaiodobenzylguanidine; SBR: specific binding ratio; SPECT: single-photon emission computed tomography; DAT: dopamine transporter; NIBS: noninvasive brain stimulation; tDCS: transcranial direct current stimulation; MAOB: monoamine oxidase B; DCI: decarboxylase inhibitor; repetitive transcranial magnetic stimulation: rTMS; diffusion tensor imaging: DTI; arterial spin labeling: ASL.

Parkinson's Disease and the COVID-19 Pandemic

Studies focusing on the relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), coronavirus disease 2019 (COVID-19), and Parkinson’s disease (PD) have provided conflicting results. We review the literature to investigate: 1) Are PD patients at higher risk for contracting COVID-19 and are there specific contributing factors to that risk? 2) How does COVID-19 affect PD symptoms? 3) How does COVID-19 present in PD patients? 4) What are the outcomes in PD patients who contract COVID-19? 5) What is the impact of COVID-19 on PD care? 6) Does COVID-19 increase the risk of developing PD? A literature search was performed from 1979 to 2020 using the terms: ‘Parkinson’s disease’ and ‘parkinsonism’ combined with: ‘COVID-19’; ‘SARS-CoV-2’ and ‘coronavirus’. It does not appear that PD is a specific risk factor for COVID-19. There is evidence for direct/indirect effects of SARS-CoV-2 on motor/non-motor symptoms of PD. Although many PD patients present with typical COVID-19 symptoms, some present atypically with isolated worsening of parkinsonian symptoms, requiring increased anti-PD therapy and having worse outcomes. Mortality data on PD patients with COVID-19 is inconclusive (ranging from 5.2%to 100%). Patients with advanced PD appear to be particularly vulnerable. Single cases of acute hypokinetic-rigid syndrome have been described but no other convincing data has been reported. The rapidity with which COVID-19 has swept across the globe has favored the proliferation of studies which lack scientific rigor and the PD literature has not been immune. A coordinated effort is required to assimilate data and answer these questions in larger PD cohorts.

Effects of exercise on proactive interference in memory: potential neuroplasticity and neurochemical mechanisms

Proactive interference occurs when consolidated memory traces inhibit new learning. This kind of interference decreases the efficiency of new learning and also causes memory errors. Exercise has been shown to facilitate some types of cognitive function; however, whether exercise reduces proactive interference to enhance learning efficiency is not well understood. Thus, this review discusses the effects of exercise on proactive memory interference and explores potential mechanisms, such as neurogenesis and neurochemical changes, mediating any effect.

The onjisaponin B metabolite tenuifolin ameliorates dopaminergic neurodegeneration in a mouse model of Parkinson's disease

Onjisaponin B (OB) is the main active ingredient of the traditional Chinese medicinal herb polygala, which is effective against neurodegenerative disorders. However, the target of OB is currently unknown. Neuroinflammation and oxidative stress are both risk factors for the pathogenesis and progression of Parkinson's disease (PD). Here, we used a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced subacute mouse model of PD to explore the efficacy and neuroprotective mechanism of OB in PD. Immunohistochemistry was used to mark dopaminergic (DA) neurons and microglia in the substantia nigra pars compact. Administration of OB (20 and 40 mg/kg) prevented the degeneration of DA neurons and improved motor impairment in the rotarod test. Furthermore, OB attenuated microglia over-activation and reduced the secretion of inflammatory factors including tumor necrosis factor-alpha, interleukin-1 beta (IL-1β) and interleukin-6 (IL-6), as determined by ELISA. Meanwhile, the activities of superoxide dismutase and malondialdehyde were used to measure the level of oxidative stress in brain homogenates and suppression of excessive lipid epoxidation and increased antioxidant enzyme activity were found in OB-treated PD mice. Finally, OB inhibits the expression of the p65 subunit of NF-κB in the nucleus and attenuated expression of the RhoA and ROCK2 proteins in PD mice. Consequently, our results show that OB ameliorates DA neurodegeneration in a MPTP-induced mouse model of PD through anti-oxidant and anti-inflammatory activities mediated via the RhoA/ROCK2 signaling pathway. This finding demonstrates that OB may be a promising drug for DA neuron degeneration, which may provide a new therapeutic agent for future discovery of drugs for PD.See video abstract: http://links.lww.com/WNR/A580.

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

This systematic review and meta-analysis examines how exercise modifies brain and behavior in healthy mice, dementia (D) and Parkinson disease (PD) models. A search was performed on the Medline and Scopus electronic databases (2008-2019). Search terms were "mice", "brain", "treadmill", "exercise", "physical exercise". In the total, 430 were found but only 103 were included. Animals n = 1,172; exercised 4-8 weeks (Range 24 h to 32 weeks), 60 min/day (Range 8-120 min per day), and 10/12 m/min (Range 0.2 m/min to 36 m/min). Hippocampus, cerebral cortex, striatum and whole brain were more frequently investigated. Exercise improved learning and memory. Meta-analysis showed that exercise increased: cerebral BDNF in health (n = 150; z = 5.8, CI 3.43-12.05; p < 0.001 I2 = 94.3 %), D (n = 124; z = 4.18, CI = 2.22-9.12; p < 0.001; I2 = 93.7 %) and PD (n = 16 z = 4.26, CI 5.03-48.73 p < 0.001 I2 = 94.8 %). TrkB improved in health (n = 84 z = 5.49, CI 3.8-17.73 p < 0.001, I2 = 0.000) and PD (n = 22; z = 3.1, CI = 2.58-67.3, p < 0.002 I2 = 93.8 %). Neurogenesis increased in health (n = 68; z = 7.08, CI 5.65-21.25 p < 0.001; I2 17.58) and D model (n = 116; z = 4.18, CI 2.22-9.12 p < 0.001 I2 93.7 %). Exercise augmented amyloid clearance (n = 166; z = 7.51 CI = 4.86-14.85, p < 0.001 I2 = 58.72) and reduced amyloid plaques in D models (n = 49; z = 4.65, CI = 3.94-15.3 p < 0.001 I2 = 0.000). In conclusion, exercise improved brain and behavior, neurogenesis in healthy and dementia models, reduced toxicity and cerebral amyloid. Evidence regarding inflammation, oxidative stress and energy metabolism were scarce. Studies examining acute vs chronic exercise, extreme training and the durability of exercise benefit were rare. Vascular or glucose metabolism changes were seldom reported.

Exercise, spinogenesis and cognitive functions

Exercise training improves mental and cognitive functions by enhancing neurogenesis and neuroprotection. Recent studies suggest the facilitation of spinogenesis across different brain regions including hippocampus and cerebral cortex by physical activity. In this article we will summarize major findings for exercise effects on synaptogenesis and spinogenesis, in order to provide mechanisms for exercise intervention of both psychiatric diseases and neurodegenerative disorders. We will also revisit major findings for molecular mechanism governing exercise-related spinogenesis, and will discuss the screening for novel factors, or exerkines, whose levels are correlated with endurance training and affect neural plasticity. We believe that further studies focusing on the molecular mechanism of exercise-mediate spinogenesis should benefit the optimization of exercise therapy in clinics and the evaluation of treatment efficiency using specific biomarkers.

Exercise induces region-specific remodeling of astrocyte morphology and reactive astrocyte gene expression patterns in male mice

Astrocytes are essential mediators of many aspects of synaptic transmission and neuroplasticity. Exercise has been demonstrated to induce neuroplasticity and synaptic remodeling, such as through mediating neurorehabilitation in animal models of neurodegeneration. However, the effects of exercise on astrocytic function, and how such changes may be relevant to neuroplasticity remain unclear. Here, we show that exercise remodels astrocytes in an exercise- and region-dependent manner as measured by GFAP and SOX9 immunohistochemistry and morphological analysis in male mice. Additionally, qRT-PCR analysis of reactive astrocyte gene expression showed an exercise-induced elevation in brain regions known to be activated by exercise. Taken together, these data demonstrate that exercise actively modifies astrocyte morphology and drives changes in astrocyte gene expression and suggest that astrocytes may be a central component to exercise-induced neuroplasticity and neurorehabilitation.