scholarly journals A Multi-Scale Computational Model of Excitotoxic Loss of Dopaminergic Cells in Parkinson’s Disease

Author(s):  
Vignayanandam R. Muddapu ◽  
V. Srinivasa Chakravarthy

ABSTRACTParkinson’s disease (PD) is a neurodegenerative disorder caused by loss of dopaminergic neurons in Substantia Nigra pars compacta (SNc). Although the exact cause of the cell death is not clear, the hypothesis that metabolic deficiency is a key facor has been gaining attention in the recent years. In the present study, we investigate this hypothesis using a multi-scale computational model of the subsystem of the basal ganglia comprising Subthalamic Nucleus (STN), Globus Pallidus externa (GPe) and SNc. The model is a multiscale model in that interactions among the three nuclei are simulated using more abstract Izhikevich neuron models, while the molecular pathways involved in cell death of SNc neurons are simulated in terms of detailed chemical kinetics. Simulation results obtained from the proposed model showed that energy deficiencies occurring at cellular and network levels could precipitate the excitotoxic loss of SNc neurons in PD. At the subcellular level, the models show how calcium elevation leads to apoptosis of SNc neurons. The therapeutic effects of several neuroprotective interventions are also simulated in the model. From neuroprotective studies, it was clear that glutamate inhibition and apoptotic signal blocker therapies were able to halt the progression of SNc cell loss when compared to other therapeutic interventions, which only slows down the progression of SNc cell loss.

2016 ◽  
Vol 10 (1) ◽  
pp. 42-58 ◽  
Author(s):  
Mohsin H.K. Roshan ◽  
Amos Tambo ◽  
Nikolai P. Pace

Parkinson’s disease [PD] is the second most common neurodegenerative disorder after Alzheimer’s disease, affecting 1% of the population over the age of 55. The underlying neuropathology seen in PD is characterised by progressive loss of dopaminergic neurons in the substantia nigra pars compacta with the presence of Lewy bodies. The Lewy bodies are composed of aggregates of α-synuclein. The motor manifestations of PD include a resting tremor, bradykinesia, and muscle rigidity. Currently there is no cure for PD and motor symptoms are treated with a number of drugs including levodopa [L-dopa]. These drugs do not delay progression of the disease and often provide only temporary relief. Their use is often accompanied by severe adverse effects. Emerging evidence from bothin vivoandin vitrostudies suggests that caffeine may reduce parkinsonian motor symptoms by antagonising the adenosine A2Areceptor, which is predominately expressed in the basal ganglia. It is hypothesised that caffeine may increase the excitatory activity in local areas by inhibiting the astrocytic inflammatory processes but evidence remains inconclusive. In addition, the co-administration of caffeine with currently available PD drugs helps to reduce drug tolerance, suggesting that caffeine may be used as an adjuvant in treating PD. In conclusion, caffeine may have a wide range of therapeutic effects which are yet to be explored, and therefore warrants further investigation in randomized clinical trials.


Antioxidants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 524
Author(s):  
Eva Alegre-Cortés ◽  
Alicia Muriel-González ◽  
Saray Canales-Cortés ◽  
Elisabet Uribe-Carretero ◽  
Guadalupe Martínez-Chacón ◽  
...  

Parkinson’s disease (PD) is a neurodegenerative disorder that is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. This neuronal loss, inherent to age, is related to exposure to environmental toxins and/or a genetic predisposition. PD-induced cell death has been studied thoroughly, but its characterization remains elusive. To date, several types of cell death, including apoptosis, autophagy-induced cell death, and necrosis, have been implicated in PD progression. In this study, we evaluated necroptosis, which is a programmed type of necrosis, in primary fibroblasts from PD patients with and without the G2019S leucine-rich repeat kinase 2 (LRRK2) mutation and in rotenone-treated cells (SH-SY5Y and fibroblasts). The results showed that programmed necrosis was not activated in the cells of PD patients, but it was activated in cells exposed to rotenone. Necrostatin-1 (Nec-1), an inhibitor of the necroptosis pathway, prevented rotenone-induced necroptosis in PD models. However, Nec-1 affected mitochondrial morphology and failed to protect mitochondria against rotenone toxicity. Therefore, despite the inhibition of rotenone-mediated necroptosis, PD models were susceptible to the effects of both Nec-1 and rotenone.


Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 612
Author(s):  
Frank C. Church

Parkinson’s disease (PD) usually presents in older adults and typically has both motor and non-motor dysfunctions. PD is a progressive neurodegenerative disorder resulting from dopaminergic neuronal cell loss in the mid-brain substantia nigra pars compacta region. Outlined here is an integrative medicine and health strategy that highlights five treatment options for people with Parkinson’s (PwP): rehabilitate, therapy, restorative, maintenance, and surgery. Rehabilitating begins following the diagnosis and throughout any additional treatment processes, especially vis-à-vis consulting with physical, occupational, and/or speech pathology therapist(s). Therapy uses daily administration of either the dopamine precursor levodopa (with carbidopa) or a dopamine agonist, compounds that preserve residual dopamine, and other specific motor/non-motor-related compounds. Restorative uses strenuous aerobic exercise programs that can be neuroprotective. Maintenance uses complementary and alternative medicine substances that potentially support and protect the brain microenvironment. Finally, surgery, including deep brain stimulation, is pursued when PwP fail to respond positively to other treatment options. There is currently no cure for PD. In conclusion, the best strategy for treating PD is to hope to slow disorder progression and strive to achieve stability with neuroprotection. The ultimate goal of any management program is to improve the quality-of-life for a person with Parkinson’s disease.


2018 ◽  
Vol 29 (5) ◽  
pp. 475-489 ◽  
Author(s):  
Ava Nasrolahi ◽  
Javad Mahmoudi ◽  
Abolfazl Akbarzadeh ◽  
Mohammad Karimipour ◽  
Saeed Sadigh-Eteghad ◽  
...  

AbstractParkinson’s disease (PD) is the second most common neurodegenerative disorder and is characterized by a spectrum of clinicopathologic signs and a complex etiology. PD results from the degeneration of dopaminergic (DAergic) neurons in the substantia nigra. Current therapies for PD are only able to alleviate symptoms without stopping disease progression. In addition, the available therapeutic strategies do not have long-lasting effects. Furthermore, these therapies cause different ranges of adverse side effects. There is great interest in neurotrophic factors (NTFs) due to their ability to promote the survival of different neural cells. These factors are divided into four families: neurotrophins, neurokines, the glial cell line-derived NTF family of ligands, and the newly recognized cerebral DA NTF/mesencephalic astrocyte-derived NTF family. The protective and therapeutic effects of these factors on DAergic neurons make them suitable for the prevention of progressive cell loss in PD. Based on the above premise, we focus on the protective effects of NTFs, especially CDNF and MANF, on nigrostriatal DAergic neurons in PD.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Faith L. Anderson ◽  
Katharine M. von Herrmann ◽  
Angeline S. Andrew ◽  
Yuliya I. Kuras ◽  
Alison L. Young ◽  
...  

AbstractParkinson’s disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms and loss of dopaminergic neurons of the substantia nigra. Inflammation and cell death are recognized aspects of PD suggesting that strategies to monitor and modify these processes may improve the management of the disease. Inflammasomes are pro-inflammatory intracellular pattern recognition complexes that couple these processes. The NLRP3 inflammasome responds to sterile triggers to initiate pro-inflammatory processes characterized by maturation of inflammatory cytokines, cytoplasmic membrane pore formation, vesicular shedding, and if unresolved, pyroptotic cell death. Histologic analysis of tissues from PD patients and individuals with nigral cell loss but no diagnosis of PD identified elevated expression of inflammasome-related proteins and activation-related “speck” formation in degenerating mesencephalic tissues compared with controls. Based on previous reports of circulating inflammasome proteins in patients suffering from heritable syndromes caused by hyper-activation of the NLRP3 inflammasome, we evaluated PD patient plasma for evidence of inflammasome activity. Multiple circulating inflammasome proteins were detected almost exclusively in extracellular vesicles indicative of ongoing inflammasome activation and pyroptosis. Analysis of plasma obtained from a multi-center cohort identified elevated plasma-borne NLRP3 associated with PD status. Our findings are consistent with others indicating inflammasome activity in neurodegenerative disorders. Findings suggest mesencephalic inflammasome protein expression as a histopathologic marker of early-stage nigral degeneration and suggest plasma-borne inflammasome-related proteins as a potentially useful class of biomarkers for patient stratification and the detection and monitoring of inflammation in PD.


2021 ◽  
Vol 22 (18) ◽  
pp. 10161
Author(s):  
Tapan Behl ◽  
Piyush Madaan ◽  
Aayush Sehgal ◽  
Sukhbir Singh ◽  
Neelam Sharma ◽  
...  

One of the utmost frequently emerging neurodegenerative diseases, Parkinson’s disease (PD) must be comprehended through the forfeit of dopamine (DA)-generating nerve cells in the substantia nigra pars compacta (SN-PC). The etiology and pathogenesis underlying the emergence of PD is still obscure. However, expanding corroboration encourages the involvement of genetic and environmental factors in the etiology of PD. The destruction of numerous cellular components, namely oxidative stress, ubiquitin-proteasome system (UPS) dysfunction, autophagy-lysosome system dysfunction, neuroinflammation and programmed cell death, and mitochondrial dysfunction partake in the pathogenesis of PD. Present-day pharmacotherapy can alleviate the manifestations, but no therapy has been demonstrated to cease disease progression. Peroxisome proliferator-activated receptors (PPARs) are ligand-directed transcription factors pertaining to the class of nuclear hormone receptors (NHR), and are implicated in the modulation of mitochondrial operation, inflammation, wound healing, redox equilibrium, and metabolism of blood sugar and lipids. Numerous PPAR agonists have been recognized to safeguard nerve cells from oxidative destruction, inflammation, and programmed cell death in PD and other neurodegenerative diseases. Additionally, various investigations suggest that regular administration of PPAR-activating non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen, indomethacin), and leukotriene receptor antagonists (montelukast) were related to the de-escalated evolution of neurodegenerative diseases. The present review elucidates the emerging evidence enlightening the neuroprotective outcomes of PPAR agonists in in vivo and in vitro models experiencing PD. Existing articles up to the present were procured through PubMed, MEDLINE, etc., utilizing specific keywords spotlighted in this review. Furthermore, the authors aim to provide insight into the neuroprotective actions of PPAR agonists by outlining the pharmacological mechanism. As a conclusion, PPAR agonists exhibit neuroprotection through modulating the expression of a group of genes implicated in cellular survival pathways, and may be a propitious target in the therapy of incapacitating neurodegenerative diseases like PD.


2018 ◽  
Author(s):  
Michal Wegrzynowicz ◽  
Dana Bar-On ◽  
Laura Calo’ ◽  
Oleg Anichtchik ◽  
Mariangela Iovino ◽  
...  

SUMMARYParkinson’s Disease (PD) is characterized by the presence of α-synuclein aggregates known as Lewy bodies and Lewy neurites, whose formation is linked to disease development. The causal relation between α-synuclein aggregates and PD is not well understood. We generated a new transgenic mouse line (MI2) expressing human, aggregation-prone truncated 1-120 α-synuclein under the control of the tyrosine hydroxylase promoter. MI2 mice exhibit progressive aggregation of α-synuclein in dopaminergic neurons of the substantia nigra pars compacta and their striatal terminals. This is associated with a progressive reduction of striatal dopamine release, reduced striatal innervation and significant nigral dopaminergic nerve cell death starting from 6 and 12 months of age, respectively. Overt impairment in motor behavior was found in MI2 mice at 20 months of age, when 50% of dopaminergic neurons are lost. These changes were associated with an increase in the number and density of 20-500nm α-synuclein species as shown by dSTORM. Treatment with the oligomer modulator anle138b, from 9-12 months of age, restored striatal dopamine release and prevented dopaminergic cell death. These effects were associated with a reduction of the inner density of α-synuclein aggregates and an increase in dispersed small α-synuclein species as revealed by dSTORM. The MI2 mouse model recapitulates the progressive dopaminergic deficit observed in PD, showing that early synaptic dysfunction precedes dopaminergic axonal loss and neuronal death that become associated with a motor deficit upon reaching a certain threshold. Our data also provide new mechanistic insight for the effect of anle138b’s function in vivo supporting that targeting α-synuclein aggregation is a promising therapeutic approach for PD.


2021 ◽  
Vol 44 (1) ◽  
pp. 87-108
Author(s):  
Gabriel E. Vázquez-Vélez ◽  
Huda Y. Zoghbi

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by degeneration of the substantia nigra pars compacta and by accumulation of α-synuclein in Lewy bodies. PD is caused by a combination of environmental factors and genetic variants. These variants range from highly penetrant Mendelian alleles to alleles that only modestly increase disease risk. Here, we review what is known about the genetics of PD. We also describe how PD genetics have solidified the role of endosomal, lysosomal, and mitochondrial dysfunction in PD pathophysiology. Finally, we highlight how all three pathways are affected by α-synuclein and how this knowledge may be harnessed for the development of disease-modifying therapeutics.


Metabolites ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 31 ◽  
Author(s):  
Anuri Shah ◽  
Pei Han ◽  
Mung-Yee Wong ◽  
Raymond Chang ◽  
Cristina Legido-Quigley

Introduction: Parkinson’s disease (PD) is the second most common neurodegenerative disorder, without any widely available curative therapy. Metabolomics is a powerful tool which can be used to identify unexpected pathway-related disease progression and pathophysiological mechanisms. In this study, metabolomics in brain, plasma and liver was investigated in an experimental PD model, to discover small molecules that are associated with dopaminergic cell loss. Methods: Sprague Dawley (SD) rats were injected unilaterally with 6-hydroxydopamine (6-OHDA) or saline for the vehicle control group into the medial forebrain bundle (MFB) to induce loss of dopaminergic neurons in the substantia nigra pars compacta. Plasma, midbrain and liver samples were collected for metabolic profiling. Multivariate and univariate analyses revealed metabolites that were altered in the PD group. Results: In plasma, palmitic acid (q = 3.72 × 10−2, FC = 1.81) and stearic acid (q = 3.84 × 10−2, FC = 2.15), were found to be increased in the PD group. Palmitic acid (q = 3.5 × 10−2) and stearic acid (q = 2.7 × 10−2) correlated with test scores indicative of motor dysfunction. Monopalmitin (q = 4.8 × 10−2, FC = −11.7), monostearin (q = 3.72 × 10−2, FC = −15.1) and myo-inositol (q = 3.81 × 10−2, FC = −3.32), were reduced in the midbrain. The liver did not have altered levels of these molecules. Conclusion: Our results show that saturated free fatty acids, their monoglycerides and myo-inositol metabolism in the midbrain and enteric circulation are associated with 6-OHDA-induced PD pathology.


2020 ◽  
Vol 21 (10) ◽  
pp. 3459 ◽  
Author(s):  
Sandra Barata-Antunes ◽  
Fábio G. Teixeira ◽  
Bárbara Mendes-Pinheiro ◽  
Ana V. Domingues ◽  
Helena Vilaça-Faria ◽  
...  

Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder. The neurodegeneration leading to incapacitating motor abnormalities mainly occurs in the nigrostriatal pathway due to the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Several animal models have been developed not only to better understand the mechanisms underlying neurodegeneration but also to test the potential of emerging disease-modifying therapies. However, despite aging being the main risk factor for developing idiopathic PD, most of the studies do not use aged animals. Therefore, this study aimed at assessing the effect of aging in the unilateral 6-hydroxydopamine (6-OHDA)-induced animal model of PD. For this, female young adult and aged rats received a unilateral injection of 6-OHDA into the medial forebrain bundle. Subsequently, the impact of aging on 6-OHDA-induced effects on animal welfare, motor performance, and nigrostriatal integrity were assessed. The results showed that aging had a negative impact on animal welfare after surgery. Furthermore, 6-OHDA-induced impairments on skilled motor function were significantly higher in aged rats when compared with their younger counterparts. Nigrostriatal histological analysis further revealed an increased 6-OHDA-induced dopaminergic cell loss in the SNpc of aged animals when compared to young animals. Overall, our results demonstrate a higher susceptibility of aged animals to 6-OHDA toxic insult.


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