Comprehensive Perspectives on Experimental Models for Parkinson's Disease

Therapeutic modulation of mitochondrial dynamics by agmatine in neurodegenerative disorders

Mitochondrial dysfunction is a pivotal factor in the pathogenesis of neurodegenerative disorders, driving neuronal degeneration through mechanisms involving oxidative stress, impaired energy production, and dysregulated calcium homeostasis. Agmatine, an endogenous polyamine derived from arginine, has garnered attention for its neuroprotective properties, including anti-inflammatory, anti-oxidative, and antiapoptotic effects. Recent studies have highlighted the potential of agmatine in preserving mitochondrial function and mitigating neurodegeneration, making it a promising candidate for therapeutic intervention. One of the key mechanisms by which agmatine exerts its neuroprotective effects is through the maintenance of mitochondrial homeostasis. Agmatine has been shown to modulate mitochondrial dynamics, promoting mitochondrial fusion and fission balance essential for cellular energy metabolism and signaling. Moreover, agmatine acts as a regulator of mitochondrial permeability transition pore (mPTP) opening, preventing excessive calcium influx and subsequent mitochondrial dysfunction. Despite promising findings, challenges such as optimizing agmatine's pharmacokinetics, determining optimal dosing regimens, and elucidating its precise molecular targets within mitochondria remain to be addressed. Future research directions should focus on developing targeted delivery systems for agmatine, investigating its interactions with mitochondrial proteins, and conducting well-designed clinical trials to evaluate its therapeutic efficacy and safety profile in neurodegenerative disorders. Overall, agmatine emerges as a novel therapeutic agent with the potential to modulate mitochondrial homeostasis and alleviate neurodegenerative pathology, offering new avenues for treating these debilitating conditions.

Parkinson-like wild-type superoxide dismutase 1 pathology induces nigral dopamine neuron degeneration in a novel murine model

Atypical wild-type superoxide dismutase 1 (SOD1) protein misfolding and deposition occurs specifically within the degenerating substantia nigra pars compacta (SNc) in Parkinson disease. Mechanisms driving the formation of this pathology and relationship with SNc dopamine neuron health are yet to be fully understood. We applied proteomic mass spectrometry and synchrotron-based biometal quantification to post-mortem brain tissues from the SNc of Parkinson disease patients and age-matched controls to uncover key factors underlying the formation of wild-type SOD1 pathology in this disorder. We also engineered two of these factors - brain copper deficiency and upregulated SOD1 protein levels - into a novel mouse strain, termed the SOCK mouse, to verify their involvement in the development of Parkinson-like wild-type SOD1 pathology and their impact on dopamine neuron health. Soluble SOD1 protein in the degenerating Parkinson disease SNc exhibited altered post-translational modifications, which may underlie changes to the enzymatic activity and aggregation of the protein in this region. These include decreased copper binding, dysregulation of physiological glycosylation, and atypical oxidation and glycation of key SOD1 amino acid residues. We demonstrated that the biochemical profile introduced in SOCK mice promotes the same post-translational modifications and the development of Parkinson-like wild-type SOD1 pathology in the midbrain and cortex. This pathology accumulates progressively with age and is accompanied by nigrostriatal degeneration and dysfunction, which occur in the absence of α-synuclein deposition. These mice do not exhibit weight loss nor spinal cord motor neuron degeneration, distinguishing them from transgenic mutant SOD1 mouse models. This study provides the first in vivo evidence that mismetallation and altered post-translational modifications precipitates wild-type SOD1 misfolding, dysfunction, and deposition in the Parkinson disease brain, which may contribute to SNc dopamine neuron degeneration. Our data position this pathology as a novel drug target for this disorder, with a particular focus on therapies capable of correcting alterations to SOD1 post-translational modifications.

Stem Cell-Based Approaches in Parkinson's Disease Research

Parkinson's disease (PD) is a neurodegenerative condition characterized by the loss of midbrain dopaminergic neurons, leading to motor symptoms. While current treatments provide limited relief, they don't alter disease progression. Stem cell technology, involving patient-specific stem cell-derived neurons, offers a promising avenue for research and personalized regenerative therapies. This article reviews the potential of stem cell-based research in PD, summarizing ongoing efforts, their limitations, and introducing innovative research models. The integration of stem cell technology and advanced models promises to enhance our understanding and treatment strategies for PD.

Monoamine Oxidase Inhibitors in Toxic Models of Parkinsonism

Monoamine oxidase inhibitors are widely used for the symptomatic treatment of Parkinson's disease (PD). They demonstrate antiparkinsonian activity in different toxin-based models induced by 6-hydroxydopamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and pesticides (rotenone and paraquat). In some models, such as MPTP-induced PD, MAO inhibitors prevent the formation of the neurotoxin MPP+ from the protoxin MPTP. Regardless of the toxin's nature, potent MAO inhibitors prevent dopamine loss reduction, the formation of hydrogen peroxide, hydrogen peroxide signaling, and the accumulation of hydrogen peroxide-derived reactive oxygen species responsible for the development of oxidative stress. It becomes increasingly clear that some metabolites of MAO inhibitors (e.g., the rasagiline metabolite 1-R-aminoindan) possess their own bio-pharmacological activities unrelated to the parent compound. In addition, various MAO inhibitors exhibit multitarget action, in which MAO-independent effects prevail. This opens new prospects in the development of novel therapeutics based on simultaneous actions on several prospective targets for the therapy of PD.

Neuroglia in neurodegeneration: Alzheimer, Parkinson, and Huntington disease

The conspicuous rise of chronic neurodegenerative diseases, including Alzheimer (AD), Parkinson (PD), and Huntington (HD) diseases, is currently without disease-modifying therapies and accompanied by an excessive rate of unsuccessful clinical trials. This reflects a profound lack of understanding of the pathogenesis of these diseases, indicating that the current paradigms guiding disease modeling and drug development are in need of reconsideration. The role of neuroglia, namely astrocytes, microglial cells, and oligodendrocytes, in the pathogenesis of neurodegenerative diseases emerged during the last decades. This chapter provides the state-of-the-art update on the changes of astrocytes, microglial cells, and oligodendrocytes in AD, PD, and HD. A growing body of evidence suggests that homeostatic and defensive functions of glial cells are compromised at different disease stages, leading to increased susceptibility of neurons to noxious stimuli, eventually resulting in their malfunction and degeneration. Investments are needed in the generation of novel preclinical models suitable for studying glial pathology, in "humanizing" research, and in-depth investigation of glial cell alterations to slow down and, possibly, halt and prevent the rise of neurodegenerative disease. Targeting glial cells opens new therapeutic avenues to treat AD, PD, and HD.

A review article on the development of dopaminergic neurons and establishment of dopaminergic neuron-based in vitro models by using immortal cell lines or stem cells to study and treat Parkinson's disease

The primary pathological hallmark of Parkinson's disease (PD) is the degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta, a critical midbrain region. In vitro models based on DA neurons provide a powerful platform for investigating the cellular and molecular mechanisms of PD and testing novel therapeutic strategies. A deep understanding of DA neuron development, including the signalling pathways and transcription factors involved, is essential for advancing PD research. This article first explores the differentiation and maturation processes of DA neurons in the midbrain, detailing the relevant signalling pathways. It then compares various in vitro models, including primary cells, immortalized cell lines, and stem cell-based models, focusing on the advantages and limitations of each. Special attention is given to the role of immortalized and stem cell models in PD research. This review aims to guide researchers in selecting the most appropriate model for their specific research goals. Ethical considerations and clinical implications of using stem cells in PD research are also discussed.

The BE (2)-M17 neuroblastoma cell line: revealing its potential as a cellular model for Parkinson's disease

Parkinson's disease is a pathology with a wide range of in vivo and in vitro models available. Among these, the SH-SY5Y neuroblastoma cell line is one of the most employed. This model expresses catecholaminergic markers and can differentiate and acquire various neuronal phenotypes. However, challenges persist, primarily concerning the variability of growth media, expression of dopaminergic markers, and a wide variety of differentiation protocols have been reported in the literature without direct comparison between them. This lack of standardized differentiation conditions impacts result reproducibility and it makes it very difficult to compare the results obtained from different research groups. An alternative cellular model is the neuroblastoma BE (2)-M17 which exhibits a high basal expression of numerous dopaminergic markers such as tyrosine hydroxylase (TH), vesicular monoamine transporter 2 (VMAT2), and dopamine transporter (DAT). The BE (2)-M17 cells show neuronal properties, grows rapidly in conventional media, and can easily be differentiated to increase their dopaminergic phenotype. In this review, we will thoroughly explore the properties of the BE (2)-M17 cell line and discuss its potential as an excellent model for studying Parkinson's disease.

Experimental models of Parkinson's disease: Challenges and Opportunities

Parkinson's disease (PD) is a widespread neurodegenerative disorder occurs due to the degradation of dopaminergic neurons present in the substantia nigra pars compacta (SNpc). Millions of people are affected by this devastating disorder globally, and the frequency of the condition increases with the increase in the elderly population. A significant amount of progress has been made in acquiring more knowledge about the etiology and the pathogenesis of PD over the past decades. Animal models have been regarded to be a vital tool for the exploration of complex molecular mechanisms involved in PD. Various animals used as models for disease monitoring include vertebrates (zebrafish, rats, mice, guinea pigs, rabbits and monkeys) and invertebrate models (Drosophila, Caenorhabditis elegans). The animal models most relevant for study of PD are neurotoxin induction-based models (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 6-Hydroxydopamine (6-OHDA) and agricultural pesticides (rotenone, paraquat), pharmacological models (reserpine or haloperidol treated rats), genetic models (α-synuclein, Leucine-rich repeat kinase 2 (LRRK2), DJ-1, PINK-1 and Parkin). Several non-mammalian genetic models such as zebrafish, Drosophila and Caenorhabditis elegance have also gained popularity in recent years due to easy genetic manipulation, presence of genes homologous to human PD, and rapid screening of novel therapeutic molecules. In addition, in vitro models (SH-SY5Y, PC12, Lund human mesencephalic (LUHMES) cells, Human induced pluripotent stem cell (iPSC), Neural organoids, organ-on-chip) are also currently in trend providing edge in investigating molecular mechanisms involved in PD as they are derived from PD patients. In this review, we explain the current situation and merits and demerits of the various animal models.

The role of neuron-like cell lines and primary neuron cell models in unraveling the complexity of neurodegenerative diseases: a comprehensive review

Neurodegenerative diseases (NDs) are characterized by the progressive loss of neurons. As to developing effective therapeutic interventions, it is crucial to understand the underlying mechanisms of NDs. Cellular models have become invaluable tools for studying the complex pathogenesis of NDs, offering insights into disease mechanisms, determining potential therapeutic targets, and aiding in drug discovery. This review provides a comprehensive overview of various cellular models used in ND research, focusing on Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Cell lines, such as SH-SY5Y and PC12 cells, have emerged as valuable tools due to their ease of use, reproducibility, and scalability. Additionally, co-culture models, involving the growth of distinct cell types like neurons and astrocytes together, are highlighted for simulating brain interactions and microenvironment. While cell lines cannot fully replicate the complexity of the human brain, they provide a scalable method for examining important aspects of neurodegenerative diseases. Advancements in cell line technologies, including the incorporation of patient-specific genetic variants and improved co-culture models, hold promise for enhancing our understanding and expediting the development of effective treatments. Integrating multiple cellular models and advanced technologies offers the potential for significant progress in unraveling the intricacies of these debilitating diseases and improving patient outcomes.

Biomarkers of Cellular Senescence and Aging: Current State-of-the-Art, Challenges and Future Perspectives

Population aging has increased the global prevalence of aging-related diseases, including cancer, sarcopenia, neurological disease, arthritis, and heart disease. Understanding aging, a fundamental biological process, has led to breakthroughs in several fields. Cellular senescence, evinced by flattened cell bodies, vacuole formation, and cytoplasmic granules, ubiquitously plays crucial roles in tissue remodeling, embryogenesis, and wound repair as well as in cancer therapy and aging. The lack of universal biomarkers for detecting and quantifying senescent cells, in vitro and in vivo, constitutes a major limitation. The applications and limitations of major senescence biomarkers, including senescence-associated β-galactosidase staining, telomere shortening, cell-cycle arrest, DNA methylation, and senescence-associated secreted phenotypes are discussed. Furthermore, explore senotherapeutic approaches for aging-associated diseases and cancer. In addition to the conventional biomarkers, this review highlighted the in vitro, in vivo, and disease models used for aging studies. Further, technologies from the current decade including multi-omics and computational methods used in the fields of senescence and aging are also discussed in this review. Understanding aging-associated biological processes by using cellular senescence biomarkers can enable therapeutic innovation and interventions to improve the quality of life of older adults.

Construct, Face, and Predictive Validity of Parkinson's Disease Rodent Models

Parkinson's disease (PD) is the second most common neurodegenerative disease globally. Current drugs only alleviate symptoms without halting disease progression, making rodent models essential for researching new therapies and understanding the disease better. However, selecting the right model is challenging due to the numerous models and protocols available. Key factors in model selection include construct, face, and predictive validity. Construct validity ensures the model replicates pathological changes seen in human PD, focusing on dopaminergic neurodegeneration and a-synuclein aggregation. Face validity ensures the model's symptoms mirror those in humans, primarily reproducing motor and non-motor symptoms. Predictive validity assesses if treatment responses in animals will reflect those in humans, typically involving classical pharmacotherapies and surgical procedures. This review highlights the primary characteristics of PD and how these characteristics are validated experimentally according to the three criteria. Additionally, it serves as a valuable tool for researchers in selecting the most appropriate animal model based on established validation criteria.

Rotenone Induces a Neuropathological Phenotype in Cholinergic-like Neurons Resembling Parkinson's Disease Dementia (PDD)

Parkinson's disease with dementia (PDD) is a neurological disorder that clinically and neuropathologically overlaps with Parkinson's disease (PD) and Alzheimer's disease (AD). Although it is assumed that alpha-synuclein ( α -Syn), amyloid beta (A β ), and the protein Tau might synergistically induce cholinergic neuronal degeneration, presently the pathological mechanism of PDD remains unclear. Therefore, it is essential to delve into the cellular and molecular aspects of this neurological entity to identify potential targets for prevention and treatment strategies. Cholinergic-like neurons (ChLNs) were exposed to rotenone (ROT, 10 μ M) for 24 h. ROT provokes loss of Δ Ψ m , generation of reactive oxygen species (ROS), phosphorylation of leucine-rich repeated kinase 2 (LRRK2 at Ser935) concomitantly with phosphorylation of α -synuclein ( α -Syn, Ser129), induces accumulation of intracellular A β (iA β ), oxidized DJ-1 (Cys106), as well as phosphorylation of TAU (Ser202/Thr205), increases the phosphorylation of c-JUN (Ser63/Ser73), and increases expression of proapoptotic proteins TP53, PUMA, and cleaved caspase 3 (CC3) in ChLNs. These neuropathological features resemble those reproduced in presenilin 1 (PSEN1) E280A ChLNs. Interestingly, anti-oxidant and anti-amyloid cannabidiol (CBD), JNK inhibitor SP600125 (SP), TP53 inhibitor pifithrin- α (PFT), and LRRK2 kinase inhibitor PF-06447475 (PF475) significantly diminish ROT-induced oxidative stress (OS), proteinaceous, and cell death markers in ChLNs compared to naïve ChLNs. In conclusion, ROT induces p- α -Syn, iA β , p-Tau, and cell death in ChLNs, recapitulating the neuropathology findings in PDD. Our report provides an excellent in vitro model to test for potential therapeutic strategies against PDD. Our data suggest that ROT induces a neuropathologic phenotype in ChLNs similar to that caused by the mutation PSEN1 E280A.

Towards a biological diagnosis of PD

Since the original description by James Parkinson, Parkinson's disease (PD) has intrigued us for over 200 years. PD is a progressive condition that is incurable so far, and affects millions of people worldwide. Over the years, our knowledge has expanded tremendously, and a range of criteria have been put forward and used to try to define PD. However, owing to the complexity of the problem, it is still not consensual how to diagnose and classify a disease that manifests with diverse features, and that responds differently to existing therapies and to those under development. We are now living a time when 'biological' information is becoming abundant, precise, and accessible enabling us to attempt to incorporate different sources of information to classify different forms of PD. These refinements are essential for basic science, as they will enable us to develop improved models for studying PD, and to implement new findings into clinical practice, as this will be the path towards effective personalized medicine.

Carpesii fructus extract exhibits neuroprotective effects in cellular and Caenorhabditis elegans models of Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) is a debilitating neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra. Despite extensive research, no definitive cure or effective disease-modifying treatment for PD exists to date. Therefore, the identification of novel therapeutic agents with neuroprotective properties is of utmost importance. Here, we aimed to investigate the potential neuroprotective effects of Carpesii fructus extract (CFE) in both cellular and Caenorhabditis elegans (C. elegans) models of PD.

METHODS

The neuroprotective effect of CFE in H2O2- or 6-OHDA-induced PC-12 cells and α-synuclein-overexpressing PC-12 cells were investigated by determining the cell viability, mitochondrial damage, reactive oxygen species (ROS) production, apoptosis, and α-synuclein expression. In NL5901, BZ555, and N2 worms, the expression of α-synuclein, motive ability, the viability of dopaminergic neurons, lifespan, and aging-related phenotypes were investigated. The signaling pathway was detected by Western blotting and validated by employing small inhibitors and RNAi bacteria.

RESULTS

In cellular models of PD, CFE significantly attenuated H2O2- or 6-OHDA-induced toxicity, as evidenced by increased cell viability and reduced apoptosis rate. In addition, CFE treatment suppressed ROS generation and restored mitochondrial membrane potential, highlighting its potential as a mitochondrial protective agent. Furthermore, CFE reduced the expression of α-synuclein in wide type (WT)-, A53T-, A30P-, or E46K-α-synuclein-overexpressing PC-12 cells. Our further findings reveal that CFE administration reduced α-synuclein expression and improved its induced locomotor deficits in NL5901 worms, protected dopaminergic neurons against 6-OHDA-induced degeneration in BZ555 worms, extended lifespan, delayed aging-related phenotypes, and enhanced the ability of stress resistance in N2 worms. Mechanistic studies suggest that the neuroprotective effects of CFE may involve the modulation of the MAPK signaling pathway, including ERK, JNK, and p38, whereas the interference of these pathways attenuated the neuroprotective effect of CFE in vitro and in vivo.

CONCLUSION

Overall, our study highlights the potential therapeutic value of CFE as a neuroprotective agent in the context of PD. Furthermore, elucidation of the active compounds of CFE will provide valuable insights for the development of novel therapeutic strategies for PD.

Azoramide prevents MPP+-induced dopaminergic neuronal death via upregulating ER chaperone BiP expression

Progressive death of dopaminergic (DA) neurons is the main cause of Parkinson's disease (PD). The discovery of drug candidates to prevent DA neuronal death is required to address the pathological aspects and alter the process of PD. Azoramide is a new small molecule compound targeting ER stress, which was originally developed for the treatment of diabetes. In this study, pre-treatment with Azoramide was found to suppress mitochondria-targeting neurotoxin MPP+-induced DA neuronal death and locomotor defects in zebrafish larvae. Further study showed that pre-treatment with Azoramide significantly attenuated MPP+-induced SH-SY5Y cell death by reducing aberrant changes in nuclear morphology, mitochondrial membrane potential, intracellular reactive oxygen species, and apoptotic biomarkers. The mechanistic study revealed that Azoramide was able to up-regulate the expression of ER chaperone BiP and thereby prevented MPP+-induced BiP decrease. Furthermore, pre-treatment with Azoramide failed to suppress MPP+-induced cytotoxicity in the presence of the BiP inhibitor HA15. Taken together, these results suggested that Azoramide is a potential neuroprotectant with pro-survival effects against MPP+-induced cell death through up-regulating BiP expression.

High Yield of Functional Dopamine-like Neurons Obtained in NeuroForsk 2.0 Medium to Study Acute and Chronic Rotenone Effects on Oxidative Stress, Autophagy, and Apoptosis

Several efforts to develop new protocols to differentiate in in vitro human mesenchymal stromal cells (hMSCs) into dopamine (DA) neurons have been reported. We have formulated NeuroForsk 2.0 medium containing fibroblast growth factor type beta (FGFb), brain-derived neurotrophic factor (BDNF), melatonin, purmorphamine, and forskolin. We report for the first time that menstrual stromal cells (MenSCs) cultured in NeuroForsk 2.0 medium for 7 days transdifferentiated into DA-like neurons (DALNs) expressing specific DA lineage markers tyrosine hydroxylase-positive cells (TH+) and DA transporter-positive (DAT+) cells and were responsive to DA-induced transient Ca2+ influx. To test the usefulness of this medium, DALNs were exposed to rotenone (ROT), a naturally occurring organic neurotoxin used extensively to chemically induce an in vitro model of Parkinson's disease (PD), which is a movement disorder characterized by the specific loss of DA neurons. We wanted to determine whether ROT induces apoptotic cell death and autophagy pathway under acute or chronic conditions in DALNs. Here, we report that acute ROT exposure induced several molecular changes in DALNS. ROT induced a loss of mitochondrial membrane potential (ΔΨm), high expression of parkin (PRKN), and high colocalization of dynamin-related protein 1 (DRP1) with the mitochondrial translocase of the outer membrane of mitochondria 20 (TOMM20) protein. Acute ROT also induced the appearance of DJ-1Cys106-SO3, as evidenced by the generation of H2O2 and oxidative stress (OS) damage. Remarkably, ROT triggered the phosphorylation of leucine-rich repeat kinase 2 (LRRK2) at residue Ser935 and phosphorylation of α-Syn at residue Ser129, a pathological indicator. ROT induced the accumulation of lipidated microtubule-associated protein 1B-light chain 3 (LC3B), a highly specific marker of autophagosomes. Finally, ROT induced cleaved caspase 3 (CC3), a marker of activated caspase 3 (CASP3) in apoptotic DALNs compared to untreated DANLs. However, the chronic condition was better at inducing the accumulation of lysosomes than the acute condition. Importantly, the inhibitor of the LRRK2 kinase PF-06447475 (PF-475) almost completely blunted ROT-induced apoptosis and reduced ROT-induced accumulation of lysosomes in both acute and chronic conditions in DALNs. Our data suggest that LRRK2 kinase regulated both apoptotic cell death and autophagy in DALNs under OS. Given that defects in mitochondrial complex I activity are commonly observed in PD, ROT works well as a chemical model of PD in both acute and chronic conditions. Therefore, prevention and treatment therapy should be guided to relieve DALNs from mitochondrial damage and OS, two of the most important triggers in the apoptotic cell death of DALNs.

Right vagus nerve stimulation improves motor behavior by exerting neuroprotective effects in Parkinson's disease rats

Background

Parkinson's disease (PD) is a common movement disorder disease. Left vagus nerve stimulation (LVNS) is a potential treatment option for PD. Compared with the left vagus nerve, the right vagus nerve is more closely connected with the midbrain dopaminergic neurons, which are the lesion locations of PD. However, whether right vagus nerve stimulation (RVNS) has a therapeutic effect on PD has not yet been studied. Therefore, in this study, we studied the therapeutic effect and underlying mechanism of RVNS using a PD rat model.

Methods

To establish the PD rat model, 8-week-old male Sprague-Dawley rats were intraperitoneally injected with rotenone for 21 days. The cuff electrodes were implanted into the right cervical vagal carotid sheaths of the rats. The right vagus nerve was continuously stimulated for 14 days using a radio stimulation system. Behavioral tests were performed before and after stimulation. Finally, tyrosine hydroxylase (TH), vesicular monoamine transporter 2 (VMAT2), and α-synuclein in the midbrain, including the substantia nigra (SN) and ventral tegmental area (VTA), were detected by immunofluorescence.

Results

A markedly lower distance traveled and rearing number was observed in the rotenone, rotenone + sham, and rotenone + RVNS groups compared to the vehicle group. After the stimulation days, the distance traveled and rearing number were both higher in the rotenone + RVNS group compared to the rotenone and rotenone + sham groups (P<0.01, P<0.0001). A remarkable increase in distance traveled and rearing number was observed in the rotenone + RVNS group after stimulation. TH expression in the vehicle group was significantly up-regulated than the other groups. RVNS markedly up-regulated TH expression level. A significantly higher expression of α-synuclein was observed in the rotenone, rotenone + sham, and rotenone + RVNS groups compared to the vehicle group. The expression of α-synuclein was lower in the rotenone + RVNS group compared to the rotenone and rotenone + sham groups. A markedly higher VMAT2 expression was observed in the vehicle group compared to other groups. RVNS significantly up-regulated VMAT2 expression.

Conclusions

The improved motor behavior and neuroprotective effects on the midbrain dopaminergic neurons in the PD rat model suggest that RVNS could be used as a potential treatment for PD.

The effects of bioactive components from the rhizome of gastrodia elata blume (Tianma) on the characteristics of Parkinson's disease

Parkinson's disease (PD) is an age-related chronic neurodegenerative disease caused by the death and degeneration of dopaminergic neurons in the substantia nigra of the midbrain. The decrease of the neurotransmitter dopamine in the patient's brain leads to various motor symptoms. PD drugs mainly enhance dopamine levels but cannot prevent or slow down the loss of dopaminergic neurons. In addition, they exhibit significant side effects and addiction issues during long-term use. Therefore, it is particularly urgent to develop novel drugs that have fewer side effects, can improve PD symptoms, and prevent the death of dopaminergic neurons. The rhizome of Gastrodia elata Blume (Tianma) is a well-known medicinal herb and has long been used as a treatment of nervous system-related diseases in China. Several clinical studies showed that formula comprising Tianma could be used as an add-on therapy for PD patients. Pharmacological studies indicated that Tianma and its bioactive components can reduce the death of dopaminergic neurons, α-synuclein accumulation, and neuroinflammation in various PD models. In this review, we briefly summarize studies regarding the effects of Tianma and its bioactive components' effects on major PD features and explore the potential use of Tianma components for the treatment of PD.

Mitochondrial dysfunction of induced pluripotent stem cells-based neurodegenerative disease modeling and therapeutic strategy

Neurodegenerative diseases (NDDs) are disorders in which neurons are lost owing to various factors, resulting in a series of dysfunctions. Their rising prevalence and irreversibility have brought physical pain to patients and economic pressure to both individuals and society. However, the pathogenesis of NDDs has not yet been fully elucidated, hampering the use of precise medication. Induced pluripotent stem cell (IPSC) modeling provides a new method for drug discovery, and exploring the early pathological mechanisms including mitochondrial dysfunction, which is not only an early but a prominent pathological feature of NDDs. In this review, we summarize the iPSC modeling approach of Alzheimer’s disease, Parkinson’s disease, and Amyotrophic lateral sclerosis, as well as outline typical mitochondrial dysfunction and recapitulate corresponding therapeutic strategies.

Characterization of neurobehavioral pattern in a zebrafish 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced model: A 96-hour behavioral study

Parkinson’s disease (PD) is the most common brain motor disorder, characterized by a substantial loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Motor impairments, such as dyskinesia, bradykinesia, and resting tremors, are the hallmarks of PD. Despite ongoing research, the exact PD pathogenesis remains elusive due to the disease intricacy and difficulty in conducting human studies. Zebrafish (Danio rerio) has emerged as an ideal model for researching PD pathophysiology. Even though 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been used to induce PD in zebrafish, behavioural findings are frequently limited to a single time point (24 hours post-injection). In this sense, we aim to demonstrate the effects of MPTP on zebrafish swimming behaviour at multiple time points. We administered a single dosage of MPTP (200μg/g bw) via intraperitoneal injection (i/p) and assessed the locomotor activity and swimming pattern at 0h, 24h, and 96h post-injection through an open field test. Analysis of the behaviour revealed significant reductions in swimming velocity (cm/s) and distance travelled (cm), concurrent with an increase in freezing maintenance (duration and bouts) in zebrafish injected with MPTP. In addition, the MPTP-injected zebrafish exhibited complex swimming patterns, as measured by the turn angle, meander, and angular velocity, and showed abnormal swimming phenotypes, including freezing, looping, and erratic movement. To conclude, MPTP administration into adult zebrafish induced hypolocomotion and elicited motor incoordination. Plus, the effects of MPTP were observable 24 hours after the injection and still detectable 96 hours later. These findings contribute to the understanding of MPTP effects on adult zebrafish, particularly in terms of swimming behaviours, and may pave the way for a better understanding of the establishment of PD animal models in the future.

Modelling Parkinson's Disease in C. elegans: Strengths and Limitations

Parkinson's disease (PD) is a common neurodegenerative disease that affects the motor system and progressively worsens with age. Current treatment options for PD mainly target symptoms, due to our limited understanding of the etiology and pathophysiology of PD. A variety of preclinical models have been developed to study different aspects of the disease. The models have been used to elucidate the pathogenesis and for testing new treatments. These models include cell models, non-mammalian models, rodent models, and non-human primate models. Over the past few decades, Caenorhabditis elegans (C. elegans) has been widely adopted as a model system due to its small size, transparent body, short generation time and life cycle, fully sequenced genome, the tractability of genetic manipulation and suitability for large scale screening for disease modifiers. Here, we review studies using C. elegans as a model for PD and highlight the strengths and limitations of the C. elegans model. Various C. elegans PD models, including neurotoxin-induced models and genetic models, are described in detail. Moreover, met.

Effects of remote ischemic conditioning on sleep complaints in Parkinson's disease-rationale, design, and protocol for a randomized controlled study

OBJECTIVE

Sleep disturbances are common non-motor symptoms of Parkinson's disease. The symptoms affect the quality of patients' life by impeding normal sleep cycles and causing excessive daytime sleepiness. Remote Ischemic Conditioning (RIC) is a therapy often used for ischemic stroke patients to minimize infarct size and maximize post-stroke neurological function. Animal experiments have shown that RIC plays a protective role for retinal ganglion cells and other critical areas of the brain of Parkinson's disease. However, whether RIC improves excessive daytime sleepiness (EDS) for patients with Parkinson's disease remains to be determined.

METHODS

This is a single-center, double-blind, and randomized controlled trial, which includes patients with Parkinson's disease with EDS. All recruited patients will be randomly assigned either to the RIC or the control group (i.e., sham-RIC) with 20 patients in each group. Both groups receive RIC or sham-RIC treatment once a day for 28 days within 24 h of enrollment. Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), Parkinson Disease Sleep Scale-2 (PDSS-2), Parkinson's Disease Questionnaire39 (PDQ39) score scales, and adverse events, such as inability to tolerate the treatment leading to suspension of the study or objective signs of tissue or neurovascular injury caused by RIC and/or sham-RIC are evaluated at 7, 14, 28, and 90 days after enrollment.

RESULTS

The primary goal of this study is to assess the feasibility of the treatments in patients with Parkinson's disease by measuring serious RIC-related adverse events and any reduced incidence of adverse events during the trial and to study potential efficacy, improvement of patients' excessive daytime sleepiness, quality of life-based on ESS, PSQI, PDSS-2, and PDQ39 scores. The secondary goal is to confirm the safety of the treatments.

CONCLUSION

This study is a prospective randomized controlled trial to determine the safety, feasibility, and potential efficacy of RIC for patients with Parkinson's disease associated with EDS.