Current and experimental treatments of Parkinson disease: A guide for neuroscientists

Retinoic acid in Parkinson's disease: Molecular insights, therapeutic advances, and future prospects

Parkinson's disease (PD) is a common and progressively worsening neurodegenerative disorder characterized by abnormal protein homeostasis and the degeneration of dopaminergic neurons, particularly in the substantia nigra pars compacta. The prevalence of PD has doubled in the past 25 years, now affecting over 8.5 million individuals worldwide, underscoring the need for effective management strategies. While current pharmacological therapies provide symptom relief, they face challenges in treating advanced PD stages. Recent research highlights the therapeutic benefits of retinoic acid (RA) in PD, demonstrating its potential to mitigate neuroinflammation and oxidative stress, regulate brain aging, promote neuronal plasticity, and influence circadian rhythm gene expression and retinoid X receptor heterodimerization. Additionally, RA helps maintain intestinal homeostasis and modulates the enteric nervous system, presenting significant therapeutic potential for managing PD. This review explores RA as a promising alternative to conventional therapies by summarizing the molecular mechanisms underlying its role in PD pathophysiology and presenting up-to-date insights into both preclinical and clinical studies of RA in PD treatment. It also delves into cutting-edge formulations incorporating RA, highlighting ongoing efforts to refine therapeutic strategies by integrating RA into novel treatments. This comprehensive overview aims to advance progress in the field, contribute to the development of effective, targeted treatments for PD, and enhance patient well-being. Further research is essential to fully explore RA's therapeutic potential and validate its efficacy in PD treatment.

GPR40 agonist ameliorates neurodegeneration and motor impairment by regulating NLRP3 inflammasome in Parkinson's disease animal models

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN) and accumulation of intracellular α-synuclein (ɑ-syn) aggregates known as Lewy bodies and Lewy neurites. Levels of polyunsaturated fatty acids (PUFAs) have previously been shown to be reduced in the SN of PD patients. G protein-coupled receptor 40 (GPR40) serves as a receptor for PUFAs, playing a role in neurodevelopment and neurogenesis. Additionally, GPR40 has been implicated in several neuropathological conditions, such as apoptosis and inflammation, suggesting its potential as a therapeutic target in PD. In this study, we investigated the neuroprotective effects of the GPR40 agonist, TUG469 in PD models. Our results demonstrated that TUG469 reduces the neurotoxicity induced by 6-OHDA in SH-SY5Y cells. In 6-OHDA-induced PD model mice, TUG469 treatment improved motor impairment, preserved dopaminergic fibers and cell bodies in the striatum (ST) or SN, and attenuated 6-OHDA-induced microgliosis and astrogliosis in the brain. Furthermore, in a PD model involving the injection of mouse ɑ-syn fibrils into the brain (mPFFs-PD model), TUG469 treatment reduced the levels of pSer129 ɑ-syn, and decreased microgliosis and astrogliosis. Our investigation also revealed that TUG469 modulates inflammasome activation, apoptosis, and autophagy in the 6-OHDA-PD model, as evidenced by the results of RNA-seq and western blotting analyses. In summary, our findings highlight the neuroprotective effects of GPR40 agonists on dopaminergic neurons and their potential as therapeutic agents for PD. These results underscore the importance of targeting GPR40 in PD treatment, particularly in mitigating neuroinflammation and preserving neuronal integrity.

Motor Efficacy of Subcutaneous DIZ102, Intravenous DIZ101 or Intestinal Levodopa/Carbidopa Infusion

BACKGROUND

It has been suggested that carbidopa at high blood concentrations may counter the therapeutic effect of levodopa in Parkinson's disease by entering the brain and blocking central levodopa conversion to dopamine. We previously demonstrated equivalent plasma levodopa concentration in patients with Parkinson's disease during 16 h of (1) intravenous carbidopa/levodopa (DIZ101) infusion, (2) subcutaneous carbidopa/levodopa (DIZ102) infusion or (3) intestinal carbidopa/levodopa gel infusion. Plasma levels of carbidopa were however approximately four times higher with DIZ101 and DIZ102 than with LCIG, and higher than those usually observed with oral levodopa/carbidopa.

OBJECTIVES

To investigate if high carbidopa blood concentrations obtained with parenteral levodopa/carbidopa (ratio 8:1) counter the effect of levodopa on motor symptoms.

METHODS

Eighteen patients with advanced Parkinson's disease were administered DIZ101, DIZ102, and intestinal levodopa/carbidopa gel for 16 h on different days in randomized order. Video recordings of a subset of the motor examination in the Unified Parkinson's Disease Rating Scale (UPDRS) were evaluated by raters blinded for treatment and time. Motor function was also measured using a wrist-worn device monitoring bradykinesia, dyskinesia, and tremor (Parkinson KinetiGraph).

RESULTS

There was no tendency for poorer levodopa effect with DIZ101 or DIZ102 as compared to LCIG.

CONCLUSION

Although DIZ101 or DIZ102 causes approximately four times higher plasma carbidopa levels than LCIG, patients responded equally well to all treatments. The results do not indicate that high plasma carbidopa levels hamper the motor efficacy of levodopa.

Luteolin for neurodegenerative diseases: a review

Neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and multiple sclerosis affect millions of people around the world. In addition to age, which is a key factor contributing to the development of all neurodegenerative diseases, genetic and environmental components are also important risk factors. Current methods of treating neurodegenerative diseases are mostly symptomatic and do not eliminate the cause of the disease. Many studies focus on searching for natural substances with neuroprotective properties that could be used as an adjuvant therapy in the inhibition of the neurodegeneration process. These compounds include flavonoids, such as luteolin, showing significant anti-inflammatory, antioxidant, and neuroprotective activity. Increasing evidence suggests that luteolin may confer protection against neurodegeneration. In this review, we summarize the scientific reports from preclinical in vitro and in vivo studies regarding the beneficial effects of luteolin in neurodegenerative diseases. Luteolin was studied most extensively in various models of Alzheimer's disease but there are also several reports showing its neuroprotective effects in models of Parkinson's disease. Though very limited, studies on possible protective effects of luteolin against Huntington's disease and multiple sclerosis are also discussed here. Overall, although preclinical studies show the potential benefits of luteolin in neurodegenerative disorders, clinical evidence on its therapeutic efficacy is still deficient.

An Overview of Epigenetic Changes in the Parkinson's Disease Brain

Parkinson's disease is a progressive neurodegenerative disorder, predominantly of the motor system. Although some genetic components and cellular mechanisms of Parkinson's have been identified, much is still unknown. In recent years, emerging evidence has indicated that non-DNA-sequence variation (in particular epigenetic mechanisms) is likely to play a crucial role in the development and progression of the disease. Here, we present an up-to-date overview of epigenetic processes including DNA methylation, DNA hydroxymethylation, histone modifications and non-coding RNAs implicated in the brain of those with Parkinson's disease. We will also discuss the limitations of current epigenetic research in Parkinson's disease, the advantages of simultaneously studying genetics and epigenetics, and putative novel epigenetic therapies.

Drug Development for Alzheimer's and Parkinson's Disease: Where Do We Go Now?

Neurodegenerative diseases (NDs) are a set of progressive, chronic, and incurable diseases characterized by the gradual loss of neurons, culminating in the decline of cognitive and/or motor functions. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common NDs and represent an enormous burden both in terms of human suffering and economic cost. The available therapies for AD and PD only provide symptomatic and palliative relief for a limited period and are unable to modify the diseases' progression. Over the last decades, research efforts have been focused on developing new pharmacological treatments for these NDs. However, to date, no breakthrough treatment has been discovered. Hence, the development of disease-modifying drugs able to halt or reverse the progression of NDs remains an unmet clinical need. This review summarizes the major hallmarks of AD and PD and the drugs available for pharmacological treatment. It also sheds light on potential directions that can be pursued to develop new, disease-modifying drugs to treat AD and PD, describing as representative examples some advances in the development of drug candidates targeting oxidative stress and adenosine A2A receptors.

Multi-timescale neuromodulation strategy for closed-loop deep brain stimulation in Parkinson's disease

Objective.Beta triggered closed-loop deep brain stimulation (DBS) shows great potential for improving the efficacy while reducing side effect for Parkinson's disease. However, there remain great challenges due to the dynamics and stochasticity of neural activities. In this study, we aimed to tune the amplitude of beta oscillations with different time scales taking into account influence of inherent variations in the basal ganglia-thalamus-cortical circuit.Approach. A dynamic basal ganglia-thalamus-cortical mean-field model was established to emulate the medication rhythm. Then, a dynamic target model was designed to embody the multi-timescale dynamic of beta power with milliseconds, seconds and minutes. Moreover, we proposed a closed-loop DBS strategy based on a proportional-integral-differential (PID) controller with the dynamic control target. In addition, the bounds of stimulation amplitude increments and different parameters of the dynamic target were considered to meet the clinical constraints. The performance of the proposed closed-loop strategy, including beta power modulation accuracy, mean stimulation amplitude, and stimulation variation were calculated to determine the PID parameters and evaluate neuromodulation performance in the computational dynamic mean-field model.Main results. The Results show that the dynamic basal ganglia-thalamus-cortical mean-field model simulated the medication rhythm with the fasted and the slowest rate. The dynamic control target reflected the temporal variation in beta power from milliseconds to minutes. With the proposed closed-loop strategy, the beta power tracked the dynamic target with a smoother stimulation sequence compared with closed-loop DBS with the constant target. Furthermore, the beta power could be modulated to track the control target under different long-term targets, modulation strengths, and bounds of the stimulation increment.Significance. This work provides a new method of closed-loop DBS for multi-timescale beta power modulation with clinical constraints.

Discovery of potent inhibitors of α-synuclein aggregation using structure-based iterative learning

Machine learning methods hold the promise to reduce the costs and the failure rates of conventional drug discovery pipelines. This issue is especially pressing for neurodegenerative diseases, where the development of disease-modifying drugs has been particularly challenging. To address this problem, we describe here a machine learning approach to identify small molecule inhibitors of α-synuclein aggregation, a process implicated in Parkinson's disease and other synucleinopathies. Because the proliferation of α-synuclein aggregates takes place through autocatalytic secondary nucleation, we aim to identify compounds that bind the catalytic sites on the surface of the aggregates. To achieve this goal, we use structure-based machine learning in an iterative manner to first identify and then progressively optimize secondary nucleation inhibitors. Our results demonstrate that this approach leads to the facile identification of compounds two orders of magnitude more potent than previously reported ones.

Video-based analysis of the blink reflex in Parkinson's disease patients

We developed a video-based tool to quantitatively assess the Glabellar Tap Reflex (GTR) in patients with idiopathic Parkinson's disease (iPD) as well as healthy age-matched participants. We also video-graphically assessed the effect of dopaminergic medication on the GTR in iPD patients, as well as the frequency and blinking duration of reflex and non-reflex blinks. The Glabellar Tap Reflex is a clinical sign seen in patients e.g. suffering from iPD. Reliable tools to quantify this sign are lacking.

METHODS

We recorded the GTR in 11 iPD patients and 12 healthy controls (HC) with a consumer-grade camera at a framerate of at least 180 images/s. In these videos, reflex and non-reflex blinks were analyzed for blink count and blinking duration in an automated fashion.

RESULTS

With our setup, the GTR can be extracted from high-framerate cameras using landmarks of the MediaPipe face algorithm. iPD patients did not habituate to the GTR; dopaminergic medication did not alter that response. iPD patients' non-reflex blinks were higher in frequency and higher in blinking duration (width at half prominence); dopaminergic medication decreased the median frequency (Before medication-HC: p < 0.001, After medication-HC: p = 0.0026) and decreased the median blinking duration (Before medication-HC: p = 0.8594, After medication-HC: p = 0.6943)-both in the direction of HC.

CONCLUSION

We developed a quantitative, video-based tool to assess the GTR and other blinking-specific parameters in HC and iPD patients. Further studies could compare the video data to electromyogram (EMG) data for accuracy and comparability, as well as evaluate the specificity of the GTR in patients with other neurodegenerative disorders, in whom the GTR can also be present.

SIGNIFICANCE

The video-based detection of the blinking parameters allows for unobtrusive measurement in patients, a safer and more comfortable option.

Levodopa-Entacapone-Carbidopa Intestinal Gel in the Treatment of Advanced Parkinson's Disease: A Single Center Real-World Experience

Levodopa-entacapone-carbidopa intestinal gel infusion is a relatively new treatment option for advanced Parkinson's disease. We aimed to describe and analyze the characteristics of de novo levodopa-entacapone-carbidopa intestinal gel therapy in 20 consecutive patients with advanced Parkinson's disease. We assessed the profile of motor complications by evaluating the following: motor fluctuations, dyskinesias, and the freezing phenomenon at baseline (before the testing period) and before discharge. The treatment significantly reduced the duration of daily hours spent in off time compared with baseline pre-treatment values from a mean of 4.8 ± 0.9 h/day to a mean of 1.4 ± 0.5 h per day (p < 0.001). The duration and severity of peak-dose dyskinesia were also significantly reduced compared with baseline values. Out of the 10 patients who reported freezing, 8 did not present this complication at the pre-discharge assessment. Significant improvements were observed in Hoehn and Yahr scale scores in both the on and off states. The levodopa-entacapone-carbidopa intestinal gel therapy was well tolerated during the follow-up period immediately after initiation. Despite a relatively severe stage of the disease, all patients experienced a significant improvement in motor fluctuations, dyskinesias, and the freezing phenomenon.

Exploring the mechanisms of kaempferol in neuroprotection: Implications for neurological disorders

Kaempferol, a flavonoid compound found in various fruits, vegetables, and medicinal plants, has garnered increasing attention due to its potential neuroprotective effects in neurological diseases. This research examines the existing literature concerning the involvement of kaempferol in neurological diseases, including stroke, Parkinson's disease, Alzheimer's disease, neuroblastoma/glioblastoma, spinal cord injury, neuropathic pain, and epilepsy. Numerous in vitro and in vivo investigations have illustrated that kaempferol possesses antioxidant, anti-inflammatory, and antiapoptotic properties, contributing to its neuroprotective effects. Kaempferol has been shown to modulate key signaling pathways involved in neurodegeneration and neuroinflammation, such as the PI3K/Akt, MAPK/ERK, and NF-κB pathways. Moreover, kaempferol exhibits potential therapeutic benefits by enhancing neuronal survival, attenuating oxidative stress, enhancing mitochondrial calcium channel activity, reducing neuroinflammation, promoting neurogenesis, and improving cognitive function. The evidence suggests that kaempferol holds promise as a natural compound for the prevention and treatment of neurological diseases. Further research is warranted to elucidate the underlying mechanisms of action, optimize dosage regimens, and evaluate the safety and efficacy of this intervention in human clinical trials, thereby contributing to the advancement of scientific knowledge in this field.

Circuit-specific gene therapy reverses core symptoms in a primate Parkinson's disease model

Parkinson's disease (PD) is a debilitating neurodegenerative disorder. Its symptoms are typically treated with levodopa or dopamine receptor agonists, but its action lacks specificity due to the wide distribution of dopamine receptors in the central nervous system and periphery. Here, we report the development of a gene therapy strategy to selectively manipulate PD-affected circuitry. Targeting striatal D1 medium spiny neurons (MSNs), whose activity is chronically suppressed in PD, we engineered a therapeutic strategy comprised of a highly efficient retrograde adeno-associated virus (AAV), promoter elements with strong D1-MSN activity, and a chemogenetic effector to enable precise D1-MSN activation after systemic ligand administration. Application of this therapeutic approach rescues locomotion, tremor, and motor skill defects in both mouse and primate models of PD, supporting the feasibility of targeted circuit modulation tools for the treatment of PD in humans.

Patient-specific models link neurotransmitter receptor mechanisms with motor and visuospatial axes of Parkinson's disease

Parkinson's disease involves multiple neurotransmitter systems beyond the classical dopaminergic circuit, but their influence on structural and functional alterations is not well understood. Here, we use patient-specific causal brain modeling to identify latent neurotransmitter receptor-mediated mechanisms contributing to Parkinson's disease progression. Combining the spatial distribution of 15 receptors from post-mortem autoradiography with 6 neuroimaging-derived pathological factors, we detect a diverse set of receptors influencing gray matter atrophy, functional activity dysregulation, microstructural degeneration, and dendrite and dopaminergic transporter loss. Inter-individual variability in receptor mechanisms correlates with symptom severity along two distinct axes, representing motor and psychomotor symptoms with large GABAergic and glutamatergic contributions, and cholinergically-dominant visuospatial, psychiatric and memory dysfunction. Our work demonstrates that receptor architecture helps explain multi-factorial brain re-organization, and suggests that distinct, co-existing receptor-mediated processes underlie Parkinson's disease.

α-Synuclein Aggregation Inhibitory and Antiplasmodial Activity of Constituents from the Australian Tree Eucalyptus cloeziana

Amyloid protein aggregates are linked to the progression of neurodegenerative conditions and may play a role in life stages of Plasmodium falciparum, the parasite responsible for malaria. We hypothesize that amyloid protein aggregation inhibitors may show antiplasmodial activity and vice versa. To test this hypothesis, we screened antiplasmodial active extracts from 25 Australian eucalypt flowers using a binding affinity mass spectrometry assay to identify molecules that bind to the Parkinson's disease-implicated protein α-syn. Myrtucommulone P (1) from a flower extract of Eucalyptus cloeziana was shown to have α-syn affinity and antiplasmodial activity and to inhibit α-syn aggregation. 1 exists as a mixture of four interconverting rotamers. Assignment of the NMR resonances of all four rotamers allowed us to define the relative configuration, conformations, and ratios of rotamers in solution. Four additional new compounds, cloeziones A-C (2-4) and cloeperoxide (5), along with three known compounds were also isolated from E. cloeziana. The structures of all compounds were elucidated using HRMS and NMR analysis, and the absolute configurations for 2-4 were determined by comparison of TDDFT-calculated and experimental ECD data. Compounds 1-3 displayed antiplasmodial activities between IC50 6.6 and 16 μM. The α-syn inhibitory and antiplasmodial activity of myrtucommulone P (1) supports the hypothesized link between antiamyloidogenic and antiplasmodial activity.

Integrating single-nucleus sequence profiling to reveal the transcriptional dynamics of Alzheimer's disease, Parkinson's disease, and multiple sclerosis

BACKGROUND

Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS) are three nervous system diseases that partially overlap clinically and genetically. However, bulk RNA-sequencing did not accurately detect the core pathogenic molecules in them. The availability of high-quality single cell RNA-sequencing data of post-mortem brain collections permits the generation of a large-scale gene expression in different cells in human brain, focusing on the molecular features and relationships between diseases and genes. We integrated single-nucleus RNA-sequencing (snRNA-seq) datasets of human brains with AD, PD, and MS to identify transcriptomic commonalities and distinctions among them.

METHODS

The snRNA-seq datasets were downloaded from Gene Expression Omnibus (GEO) database. The Seurat package was used for snRNA-seq data processing. The uniform manifold approximation and projection (UMAP) were utilized for cluster identification. The FindMarker function in Seurat was used to identify the differently expressed genes. Functional enrichment analysis was carried out using the Gene Set Enrichment Analysis (GSEA) and Gene ontology (GO). The protein-protein interaction (PPI) analysis of differentially expressed genes (DEGs) was analyzed using STRING database ( http://string-db.org ). SCENIC analysis was performed using utilizing pySCENIC (v0.10.0) based on the hg19-tss-centered-10 kb-10species databases. The analysis of potential therapeutic drugs was analyzed on Connectivity Map ( https://clue.io ).

RESULTS

The gene regulatory network analysis identified several hub genes regulated in AD, PD, and MS, in which HSPB1 and HSPA1A were key molecules. These upregulated HSP family genes interact with ribosome genes in AD and MS, and with immunomodulatory genes in PD. We further identified several transcriptional regulators (SPI1, CEBPA, TFE3, GRHPR, and TP53) of the hub genes, which has important implications for uncovering the molecular crosstalk among AD, PD, and MS. Arctigenin was identified as a potential therapeutic drug for AD, PD, and MS.

CONCLUSIONS

Together, the integrated snRNA-seq data and findings have significant implications for unraveling the shared and unique molecular crosstalk among AD, PD, and MS. HSPB1 and HSPA1A as promising targets involved in the pathological mechanisms of neurodegenerative diseases. Additionally, the identification of arctigenin as a potential therapeutic drug for AD, PD, and MS further highlights its potential in treating these neurological disorders. These discoveries lay the groundwork for future research and interventions to enhance our understanding and treatment of AD, PD, and MS.

Targeting the central nervous system: From synthetic nanoparticles to extracellular vesicles-Focus on Alzheimer's and Parkinson's disease

Neurodegenerative diseases (NDs) such as Alzheimer's disease (AD) and Parkinson's disease (PD) are an accelerating global health problem as life expectancy rises worldwide. Despite their significant burden in public health systems to date, the existing treatments only manage the symptoms without slowing down disease progression. Thus, the ongoing neurodegenerative process remains untreated. Moreover, the stronghold of the brain-the blood-brain barrier (BBB)-prevents drug penetrance and dwindles effective treatments. In the last years, nanotechnology-based drug delivery systems (DDS) have become a promising approach to target and treat these disorders related to the central nervous system (CNS). PLGA based nanoparticles (NPs) were the first employed DDS for effective drug delivery. However, the poor drug loading capacity and localized immunogenicity prompted the scientific community to move to another DDS such as lipid-based NPs. Despite the lipid NPs' safety and effectiveness, their off-target accumulation together with the denominated CARPA (complement activation-related pseudo allergy) reaction has limited their complete clinical translation. Recently, biological NPs naturally secreted by cells, termed as extracellular vesicles (EVs) have emerged as promising more complex biocompatible DDS. In addition, EVs act as dual players in NDs treatment, as a "cell free" therapy themselves, as well as new biological NPs with numerous characteristics that qualify them as promising carriers over synthetic DDS. The present review aims to display advantages, drawbacks, current limitations and future prospective of the previously cited synthetic and biological DDS to enter the brain and treat one of 21st century most challenging diseases, NDs. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Gut-to-brain spreading of pathology in synucleinopathies: A focus on molecular signalling mediators

Synucleinopathies are a group of neurodegenerative disorders, classically characterized by the accumulation of aggregated alpha synuclein (aSyn) in the central nervous system. Parkinson's disease (PD) and multiple system atrophy (MSA) are the two prominent members of this family. Current treatment options mainly focus on the motor symptoms of these diseases. However, non-motor symptoms, including gastrointestinal (GI) symptoms, have recently gained particular attention, as they are frequently associated with synucleinopathies and often arise before motor symptoms. The gut-origin hypothesis has been proposed based on evidence of an ascending spreading pattern of aggregated aSyn from the gut to the brain, as well as the comorbidity of inflammatory bowel disease and synucleinopathies. Recent advances have shed light on the mechanisms underlying the progression of synucleinopathies along the gut-brain axis. Given the rapidly expanding pace of research in the field, this review presents a summary of the latest findings on the gut-to-brain spreading of pathology and potential pathology-reinforcing mediators in synucleinopathies. Here, we focus on 1) gut-to-brain communication pathways, including neuronal pathways and blood circulation, and 2) potential molecular signalling mediators, including bacterial amyloid proteins, microbiota dysbiosis-induced alterations in gut metabolites, as well as host-derived effectors, including gut-derived peptides and hormones. We highlight the clinical relevance and implications of these molecular mediators and their possible mechanisms in synucleinopathies. Moreover, we discuss their potential as diagnostic markers in distinguishing the subtypes of synucleinopathies and other neurodegenerative diseases, as well as for developing novel individualized therapeutic options for synucleinopathies.

Astrocyte-to-neuron reprogramming and crosstalk in the treatment of Parkinson's disease

Parkinson's disease (PD) is currently the fastest growing disabling neurological disorder worldwide, with motor and non-motor symptoms being its main clinical manifestations. The primary pathological features include a reduction in the number of dopaminergic neurons in the substantia nigra and decrease in dopamine levels in the nigrostriatal pathway. Existing treatments only alleviate clinical symptoms and do not stop disease progression; slowing down the loss of dopaminergic neurons and stimulating their regeneration are emerging therapies. Preclinical studies have demonstrated that transplantation of dopamine cells generated from human embryonic or induced pluripotent stem cells can restore the loss of dopamine. However, the application of cell transplantation is limited owing to ethical controversies and the restricted source of cells. Until recently, the reprogramming of astrocytes to replenish lost dopaminergic neurons has provided a promising alternative therapy for PD. In addition, repair of mitochondrial perturbations, clearance of damaged mitochondria in astrocytes, and control of astrocyte inflammation may be extensively neuroprotective and beneficial against chronic neuroinflammation in PD. Therefore, this review primarily focuses on the progress and remaining issues in astrocyte reprogramming using transcription factors (TFs) and miRNAs, as well as exploring possible new targets for treating PD by repairing astrocytic mitochondria and reducing astrocytic inflammation.

Dopamine agonists in Parkinson's disease: Impact of D1-like or D2-like dopamine receptor subtype selectivity and avenues for future treatment

Dopamine agonists (DAs) have demonstrated efficacy for the treatment of Parkinson's disease (PD) but are limited by adverse effects (AEs). DAs can vary considerably in their receptor subtype selectivity and affinity, chemical composition, receptor occupancy, and intrinsic activity on the receptor. Most currently approved DAs for PD treatment primarily target D2/D3 (D2-like) dopamine receptors. However, selective activation of D1/D5 (D1-like) dopamine receptors may enable robust activation of motor function while avoiding AEs related to D2/D3 receptor agonism. Full D1/D5 receptor-selective agonists have been explored in small, early-phase clinical studies, and although their efficacy for motor symptoms was robust, challenges with pharmacokinetics, bioavailability, cardiovascular AEs, and dyskinesia rates similar to levodopa prevented clinical advancement. Generally, repeated dopaminergic stimulation with full DAs is associated with frontostriatal dysfunction and sensitization that may induce plastic changes in the motor system, and neuroadaptations that produce long-term motor and nonmotor complications, respectively. Recent preclinical and clinical studies suggest that a D1/D5 receptor-selective partial agonist may hold promise for providing sustained, predictable, and robust motor control, while reducing risk for motor complications (e.g., levodopa-induced dyskinesia) and nonmotor AEs (e.g., impulse control disorders and excessive daytime sleepiness). Clinical trials are ongoing to evaluate this hypothesis. The potential emerging availability of novel dopamine receptor agonists with selective dopamine receptor pharmacology suggests that the older terminology "dopamine agonist" may need revision to distinguish older-generation D2/D3-selective agonists from D1/D5-selective agonists with distinct efficacy and tolerability characteristics.

Two-photon microendoscope for label-free imaging in stereotactic neurosurgery

We demonstrate a gradient refractive index (GRIN) microendoscope with an outer diameter of ∼1.2 mm and a length of ∼186 mm that can fit into a stereotactic surgical cannula. Two photon imaging at an excitation wavelength of 900 nm showed a field of view of ∼180 microns and a lateral and axial resolution of 0.86 microns and 9.6 microns respectively. The microendoscope was tested by imaging autofluorescence and second harmonic generation (SHG) in label-free human brain tissue. Furthermore, preliminary image analysis indicates that image classification models can predict if an image is from the subthalamic nucleus or the surrounding tissue using conventional, bench-top two-photon autofluorescence.

Self-healing hydrogel as an injectable implant: translation in brain diseases

Tissue engineering biomaterials are aimed to mimic natural tissue and promote new tissue formation for the treatment of impaired or diseased tissues. Highly porous biomaterial scaffolds are often used to carry cells or drugs to regenerate tissue-like structures. Meanwhile, self-healing hydrogel as a category of smart soft hydrogel with the ability to automatically repair its own structure after damage has been developed for various applications through designs of dynamic crosslinking networks. Due to flexibility, biocompatibility, and ease of functionalization, self-healing hydrogel has great potential in regenerative medicine, especially in restoring the structure and function of impaired neural tissue. Recent researchers have developed self-healing hydrogel as drug/cell carriers or tissue support matrices for targeted injection via minimally invasive surgery, which has become a promising strategy in treating brain diseases. In this review, the development history of self-healing hydrogel for biomedical applications and the design strategies according to different crosslinking (gel formation) mechanisms are summarized. The current therapeutic progress of self-healing hydrogels for brain diseases is described as well, with an emphasis on the potential therapeutic applications validated by in vivo experiments. The most recent aspect as well as the design rationale of self-healing hydrogel for different brain diseases is also addressed.

Structure-Based Design of Novel MAO-B Inhibitors: A Review

With the significant growth of patients suffering from neurodegenerative diseases (NDs), novel classes of compounds targeting monoamine oxidase type B (MAO-B) are promptly emerging as distinguished structures for the treatment of the latter. As a promising function of computer-aided drug design (CADD), structure-based virtual screening (SBVS) is being heavily applied in processes of drug discovery and development. The utilization of molecular docking, as a helping tool for SBVS, is providing essential data about the poses and the occurring interactions between ligands and target molecules. The current work presents a brief discussion of the role of MAOs in the treatment of NDs, insight into the advantages and drawbacks of docking simulations and docking software, and a look into the active sites of MAO-A and MAO-B and their main characteristics. Thereafter, we report new chemical classes of MAO-B inhibitors and the essential fragments required for stable interactions focusing mainly on papers published in the last five years. The reviewed cases are separated into several chemically distinct groups. Moreover, a modest table for rapid revision of the revised works including the structures of the reported inhibitors together with the utilized docking software and the PDB codes of the crystal targets applied in each study is provided. Our work could be beneficial for further investigations in the search for novel, effective, and selective MAO-B inhibitors.

Rosinidin inhibits NF-κB/ Nrf2/caspase-3 expression and restores neurotransmitter levels in rotenone-activated Parkinson's disease

Objectives

The examination was sighted to study the preventive effects of rosinidin against rotenone-activated Parkinson's disease in rats.

Methods

Animals were randamoized into five groups: I-saline, II-rotenone (0.5 mg/kg/b.wt.), III- IV-10 and 20 mg/kg rosinidin after rotenone and V-20 mg/kg rosinidin per se for 28 days and were assigned for behavioral analysis., Biochemical parameters i.e. lipid peroxidation, endogenous antioxidants, nitrite level, neurotransmitter levels, proinflammatory biomarkers such as interleukin- 6 (IL-6), tumor necrosis factor-α, IL-1β, nuclear factor kappa B, nuclear factor erythroid 2-related factor 2, and caspase-3 were assessed on the 29th day of the research.

Results

Rosinidin augmented the effectiveness of rotenone on akinesia, catalepsy, forced-swim test, rotarod, and open-field test. Biochemical findings indicated that treatment of rosinidin showed restoring neuroinflammatory cytokines, antioxidants, and neurotransmitter levels in rotenone-injected rats.

Conclusion

As a result of rosinidin treatment, the brain was protected from oxidative stress-induced neuronal damage and inhibited neuroinflammatory cytokines.

Risk factors for postoperative complications in patients with Parkinson disease: A single center retrospective cohort study

Surgical treatment for patients with Parkinson disease (PD) under general anesthesia has become frequent. PD is a significant predictor of postoperative complications. However, the factors that predict complications in patients with PD remain unknown. We retrospectively recruited patients with PD who underwent surgery between April 2015 and March 2019. The prevalence of postoperative complications was analyzed. We compared the patient characteristics, medical data, and surgical data between patients with and without postoperative complications. We also estimated the odds ratios (OR) for postoperative complications in patients with PD who underwent surgery. Sixty-five patients were enrolled. Eighteen patients presented with 22 complications, including urinary tract infections (UTI) (n = 3; 5%), pneumonia (n = 1; 2%), surgical site infections (SSI) (n = 3; 5%), postoperative delirium (POD) (n = 7; 10%), and others (n = 8; 12%). Four patients presented with 2 complications each. The operation time, the red blood cell transfusion and the rate of rotigotine usage were higher in patients with complications than those without (314 ± 197 min vs 173 ± 145 min, P = .006; 0 [0-560] mL vs 0 [0-0] mL, P = .02; 39% vs 6%, P = .003, respectively) (mean ± standard deviation or median [interquartile range]). Preoperative rotigotine usage (OR: 9.33; 95% confidential interval [CI]: 2.07-42.07; P = .004) was an independent risk factors for postoperative complications. The findings indicate that clinicians should closely monitor postoperative complications when patients with PD who have received transdermal dopamine agonists undergone longer time surgery.

Protective Effect of Hirsutidin against Rotenone-Induced Parkinsonism via Inhibition of Caspase-3/Interleukins-6 and 1β

A participant of the chemical family recognized as anthocyanins, hirsutidin is an O-methylated anthocyanidin. It is a natural substance, i.e., existing in Catharanthus roseus (Madagascar periwinkle), the predominant component in petals, as well as callus cultures. The literature review indicated a lack of scientifically verified findings on hirsutidin's biological activities, particularly its anti-Parkinson's capabilities. Using the information from the previous section as a reference, a present study has been assessed to evaluate the anti-Parkinson properties of hirsutidin against rotenone-activated Parkinson's in experimental animals. For 28 days, rats received hirsutidin at a dose of 10 mg/kg and rotenone at a dose of 0.5 mg/kg s.c. to test the neuroprotective effects. The hirsutidin was given 1 h before the rotenone. Behavioral tests, including the rotarod test, catalepsy, Kondziela's inverted screen activity, and open-field analysis, were performed. The levels of neurotransmitters (5-HT, DOPAC, 5-HIAA, dopamine, and HVA), neuroinflammatory markers (TNF-α, IL-6, IL-1β, caspase-3), an endogenous antioxidant, nitrite content, and acetylcholine were measured in all the rats on the 29th day. Hirsutidin exhibited substantial behavioral improvement in the rotarod test, catalepsy, Kondziela's inverted screen activity, and open-field test. Furthermore, hirsutidin restored neuroinflammatory markers, cholinergic function, nitrite content, neurotransmitters, and endogenous antioxidant levels. According to the study, hirsutidin has anti-inflammatory and antioxidant characteristics. As a result, it implies that hirsutidin may have anti-Parkinsonian effects in rats.

Design, synthesis and evaluation of novel monoamine oxidase B (MAO-B) inhibitors with improved pharmacokinetic properties for Parkinson's disease

A series of novel ((benzofuran-5-yl)methyl)pyrrolidine-2-carboxamide derivatives were designed, synthesized and evaluated as MAO-B inhibitors. SAR studies indicated that cyclizing benzyl ether into benzofuran ring resulted in the most potent MAO-B inhibitor (IC₅₀ = 0.037 μM), (2S,4S)-4-fluoro-1-((2-(4-fluorophenyl) benzofuran-5-yl)methyl)pyrrolidine-2-carboxamide (C14). PK properties of C14 in rats and mice were significantly improved compared to our previous candidate and safinamide, indicating that benzofuran moiety is essential for improving PK properties. Moreover, C14 displayed good metabolic stability and brain-blood barrier permeability, as well as favorable in vitro properties. Finally, C14 significantly inhibited MAO-B in the mouse brain. C14 exhibited a potential efficacy for DA deficits in the MPTP-induced mouse model and significantly increased DA concentration in the striatum. Thus, we identified that C14 may be a promising drug candidate for PD treatment.

Exploration and Exploitation Approaches Based on Generative Machine Learning to Identify Potent Small Molecule Inhibitors of α-Synuclein Secondary Nucleation

The high attrition rate in drug discovery pipelines is an especially pressing issue for Parkinson's disease, for which no disease-modifying drugs have yet been approved. Numerous clinical trials targeting α-synuclein aggregation have failed, at least in part due to the challenges in identifying potent compounds in preclinical investigations. To address this problem, we present a machine learning approach that combines generative modeling and reinforcement learning to identify small molecules that perturb the kinetics of aggregation in a manner that reduces the production of oligomeric species. Training data were obtained by an assay reporting on the degree of inhibition of secondary nucleation, which is the most important mechanism of α-synuclein oligomer production. This approach resulted in the identification of small molecules with high potency against secondary nucleation.

Functionality and Quality of Life with Parkinson's Disease after Use of a Dynamic Upper Limb Orthosis: A Pilot Study

Parkinson's disease (PD) is a chronic, neurodegenerative movement disorder, whose symptoms have a negative impact on quality of life and functionality. Although its main treatment is pharmacological, non-pharmacological aids such as the dynamic elastomeric fabric orthosis (DEFO) merit an evaluation. Our objective is to assess the DEFO in upper limb (UL) functional mobility and in the quality of life of PD patients. A total of 40 patients with PD participated in a randomized controlled crossover study, and were assigned to a control group (CG) and to an experimental group (EG). Both groups used the DEFO for two months, the experimental group the first two months of the study and the control group the last two. Motor variables were measured in the ON and OFF states at the baseline assessment and at two months. Differences from the baseline assessment were observed in some motor items of the Kinesia assessment, such as rest tremor, amplitude, rhythm or alternating movements in the ON and OFF states with and without orthosis. No differences were found in the unified Parkinson's disease rating scale (UPDRS) or the PD quality-of-life questionnaire. The DEFO improves some motor aspects of the UL in PD patients but this does not translate to the amelioration of the standard of functional and quality-of-life scales.

Kinases control of regulated cell death revealing druggable targets for Parkinson's disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder in the world. Motor impairment seen in PD is associated with dopaminergic neurotoxicity in the striatum, and dopaminergic neuronal death in the substantia nigra pars compacta. Cell death has a significant effect on the development and progression of PD. Extensive research over the last few decades has unveiled new regulated cell death (RCD) mechanisms that are not dependent on apoptosis such as necroptosis, ferroptosis, and others. In this review, we will overview the mechanistic pathways of different types of RCD. Unlike accidental cell death, RCD subroutines can be regulated and the RCD-associated kinases are potential druggable targets. Hence, we will address an overview and analysis of different kinases regulating apoptosis such as receptor-interacting protein kinase 1 (RIPK-1), RIPK3, mixed lineage kinase (MLK), Ataxia telangiectasia muted (ATM), cyclin-dependent kinase (CDK), death-associated protein kinase 1 (DAPK1), Apoptosis-signaling kinase-1 (ASK-1), and Leucine-rich repeat kinase-2 (LRRK2). In addition to the role of RIPK1, RIPK3, and Mixed Lineage Kinase Domain like Pseudokinase (MLKL) in necroptosis. We also overview functions of AMP-kinase (AMPK), protein kinase C (PKC), RIPK3, and ATM in ferroptosis. We will recap the anti-apoptotic, anti-necroptotic, and anti-ferroptotic effects of different kinase inhibitors in different models of PD. Finally, we will discuss future challenges in the repositioning of kinase inhibitors in PD. In conclusion, this review kicks-start targeting RCD from a kinases perspective, opening novel therapeutic disease-modifying therapeutic avenues for PD.

Current Treatments and New, Tentative Therapies for Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative pathology, the origin of which is associated with the death of neuronal cells involved in the production of dopamine. The prevalence of PD has increased exponentially. The aim of this review was to describe the novel treatments for PD that are currently under investigation and study and the possible therapeutic targets. The pathophysiology of this disease is based on the formation of alpha-synuclein folds that generate Lewy bodies, which are cytotoxic and reduce dopamine levels. Most pharmacological treatments for PD target alpha-synuclein to reduce the symptoms. These include treatments aimed at reducing the accumulation of alpha-synuclein (epigallocatechin), reducing its clearance via immunotherapy, inhibiting LRRK2, and upregulating cerebrosidase (ambroxol). Parkinson’s disease continues to be a pathology of unknown origin that generates a significant social cost for the patients who suffer from it. Although there is still no definitive cure for this disease at present, there are numerous treatments available aimed at reducing the symptomatology of PD in addition to other therapeutic alternatives that are still under investigation. However, the therapeutic approach to this pathology should include a combination of pharmacological and non-pharmacological strategies to maximise outcomes and improve symptomatological control in these patients. It is therefore necessary to delve deeper into the pathophysiology of the disease in order to improve these treatments and therefore the quality of life of the patients.

Barbigerone Potentially Alleviates Rotenone-Activated Parkinson's Disease in a Rodent Model by Reducing Oxidative Stress and Neuroinflammatory Cytokines

BACKGROUND

Parkinson's disease (PD) is a common age-related and slowly progressive neurodegenerative disease that affects approximately 1% of the elderly population. In recent years, phytocomponents have aroused considerable interest in the research for PD treatment as they provide a plethora of active compounds including antioxidant and anti-inflammatory compounds. Herein, we aimed to investigate the anti-Parkinson's effect of barbigerone, a natural pyranoisoflavone possessing antioxidant activity in a rotenone-induced rat model of PD.

METHODS

To evaluate antioxidant activity, a 0.5 mg/kg dose of rotenone was injected subcutaneously into rats. Barbigerone (10 and 20 mg/kg) was administered to rats for 28 days 1 h prior to rotenone. All behavioral parameters were assessed before sacrificing the rats. On the 29th day, all of the rats were humanely killed and assessed for biochemical changes in antioxidant enzymes (superoxide dismutase, glutathione, malondialdehyde, and catalase), neurotransmitter levels (dopamine, 5-hydroxyindoleacetic acid, serotonin, dihydroxyphenylacetic acid, and homovanillic acid levels), and neuroinflammatory cytokines [interleukin (IL)-1β, tumor necrosis factor-α, nuclear factor kappa B, and IL-6].

RESULTS

The data presented in this study has shown that barbigerone attenuated rotenone-induced motor deficits including the rotarod test, catalepsy, akinesia, and open-field test. Additionally, barbigerone has shown improvements in the biochemical and neuroinflammatory parameters in the rotenone-induced rat model of PD.

CONCLUSION

The results demonstrated that barbigerone exhibits antioxidant and anti-inflammatory actions via reducing oxidative stress and inflammatory cytokines. Altogether, these findings suggest that barbigerone could potentially be utilized as a therapeutic agent against PD.

PPARs and Their Neuroprotective Effects in Parkinson's Disease: A Novel Therapeutic Approach in α-Synucleinopathy?

Parkinson's disease (PD) is the most common α-synucleinopathy worldwide. The pathognomonic hallmark of PD is the misfolding and propagation of the α-synuclein (α-syn) protein, observed in post-mortem histopathology. It has been hypothesized that α-synucleinopathy triggers oxidative stress, mitochondrial dysfunction, neuroinflammation, and synaptic dysfunction, leading to neurodegeneration. To this date, there are no disease-modifying drugs that generate neuroprotection against these neuropathological events and especially against α-synucleinopathy. Growing evidence suggests that peroxisome proliferator-activated receptor (PPAR) agonists confer neuroprotective effects in PD, however, whether they also confer an anti-α-synucleinopathy effect is unknown. Here we analyze the reported therapeutic effects of PPARs, specifically the gamma isoform (PPARγ), in preclinical PD animal models and clinical trials for PD, and we suggest possible anti-α-synucleinopathy mechanisms acting downstream from these receptors. Elucidating the neuroprotective mechanisms of PPARs through preclinical models that mimic PD as closely as possible will facilitate the execution of better clinical trials for disease-modifying drugs in PD.

Small molecules to perform big roles: The search for Parkinson's and Huntington's disease therapeutics

Neurological motor disorders (NMDs) such as Parkinson's disease and Huntington's disease are characterized by the accumulation and aggregation of misfolded proteins that trigger cell death of specific neuronal populations in the central nervous system. Differential neuronal loss initiates the impaired motor control and cognitive function in the affected patients. Although major advances have been carried out to understand the molecular basis of these diseases, to date there are no treatments that can prevent, cure, or significantly delay the progression of the disease. In this context, strategies such as gene editing, cellular therapy, among others, have gained attention as they effectively reduce the load of toxic protein aggregates in different models of neurodegeneration. Nevertheless, these strategies are expensive and difficult to deliver into the patients' nervous system. Thus, small molecules and natural products that reduce protein aggregation levels are highly sought after. Numerous drug discovery efforts have analyzed large libraries of synthetic compounds for the treatment of different NMDs, with a few candidates reaching clinical trials. Moreover, the recognition of new druggable targets for NMDs has allowed the discovery of new small molecules that have demonstrated their efficacy in pre-clinical studies. It is also important to recognize the contribution of natural products to the discovery of new candidates that can prevent or cure NMDs. Additionally, the repurposing of drugs for the treatment of NMDs has gained huge attention as they have already been through clinical trials confirming their safety in humans, which can accelerate the development of new treatment. In this review, we will focus on the new advances in the discovery of small molecules for the treatment of Parkinson's and Huntington's disease. We will begin by discussing the available pharmacological treatments to modulate the progression of neurodegeneration and to alleviate the motor symptoms in these diseases. Then, we will analyze those small molecules that have reached or are currently under clinical trials, including natural products and repurposed drugs.

Wuzi Yanzong Pill Plays A Neuroprotective Role in Parkinson's Disease Mice via Regulating Unfolded Protein Response Mediated by Endoplasmic Reticulum Stress

OBJECTIVE

To investigate the protective effects and its possible mechanism of Wuzi Yanzong Pill (WYP) on Parkinson's disease (PD) model mice.

METHODS

Thirty-six C57BL/6 male mice were randomly assigned to 3 groups including normal, PD, and PD+WYP groups, 12 mice in each group. One week of intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used to establish the classical PD model in mice. Meanwhile, mice in the PD+WYP group were administrated with 16 g/kg WYP, twice daily by gavage. After 14 days of administration, gait test, open field test and pole test were measured to evaluate the movement function. Tyrosine hydroxylase (TH) neurons in substantia nigra of midbrain and binding immunoglobulin heavy chain protein (GRP78) in striatum and cortex were observed by immunohistochemistry. The levels of TH, GRP78, p-PERK, p-eIF2α, ATF4, p-IRE1α, XBP1, ATF6, CHOP, ASK1, p-JNK, Caspase-12, -9 and -3 in brain were detected by Western blot.

RESULTS

Compared with the PD group, WYP treatment ameliorated gait balance ability in PD mice (P<0.05). Similarly, WYP increased the total distance and average speed (P<0.05 or P<0.01), reduced rest time and pole time (P<0.05). Moreover, WYP significantly increased TH positive cells (P<0.01). Immunofluorescence showed WYP attenuated the levels of GRP78 in striatum and cortex. Meanwhile, WYP treatment significantly decreased the protein expressions of GRP78, p-PERK, p-eIF2α, ATF4, p-IRE1 α, XBP1, CHOP, Caspase-12 and Caspase-9 (P<0.05 or P<0.01).

CONCLUSIONS

WYP ameliorated motor symptoms and pathological lesion of PD mice, which may be related to the regulation of unfolded protein response-mediated signaling pathway and inhibiting the endoplasmic reticulum stress-mediated neuronal apoptosis pathway.

Regulation and modulation of biogenic amine neurotransmission in Drosophila and Caenorhabditis elegans

Neurotransmitters are crucial for the relay of signals between neurons and their target. Monoamine neurotransmitters dopamine (DA), serotonin (5-HT), and histamine are found in both invertebrates and mammals and are known to control key physiological aspects in health and disease. Others, such as octopamine (OA) and tyramine (TA), are abundant in invertebrates. TA is expressed in both Caenorhabditis elegans and Drosophila melanogaster and plays important roles in the regulation of essential life functions in each organism. OA and TA are thought to act as the mammalian homologs of epinephrine and norepinephrine respectively, and when triggered, they act in response to the various stressors in the fight-or-flight response. 5-HT regulates a wide range of behaviors in C. elegans including egg-laying, male mating, locomotion, and pharyngeal pumping. 5-HT acts predominantly through its receptors, of which various classes have been described in both flies and worms. The adult brain of Drosophila is composed of approximately 80 serotonergic neurons, which are involved in modulation of circadian rhythm, feeding, aggression, and long-term memory formation. DA is a major monoamine neurotransmitter that mediates a variety of critical organismal functions and is essential for synaptic transmission in invertebrates as it is in mammals, in which it is also a precursor for the synthesis of adrenaline and noradrenaline. In C. elegans and Drosophila as in mammals, DA receptors play critical roles and are generally grouped into two classes, D1-like and D2-like based on their predicted coupling to downstream G proteins. Drosophila uses histamine as a neurotransmitter in photoreceptors as well as a small number of neurons in the CNS. C. elegans does not use histamine as a neurotransmitter. Here, we review the comprehensive set of known amine neurotransmitters found in invertebrates, and discuss their biological and modulatory functions using the vast literature on both Drosophila and C. elegans. We also suggest the potential interactions between aminergic neurotransmitters systems in the modulation of neurophysiological activity and behavior.

Emerging point-of-care autologous cellular therapy using adipose-derived stromal vascular fraction for neurodegenerative diseases

Neurodegenerative disorders are characterized by the gradual decline and irreversible loss of cognitive functions and CNS structures. As therapeutic recourse stagnates, neurodegenerative diseases will cost over a trillion dollars by 2050. A dearth of preventive and regenerative measures to hinder regression and enhance recovery has forced patients to settle for traditional therapeutics designed to manage symptoms, leaving little hope for a cure. In the last decade, pre-clinical animal models and clinical investigations in humans have demonstrated the safety and promise of an emerging cellular product from subcutaneous fat. The adipose-derived stromal vascular fraction (SVF) is an early intervention and late-stage novel 'at point' of care cellular treatment, demonstrating improvements in clinical applications for Multiple Sclerosis, Alzheimer's disease, and Parkinson's disease. SVF is a heterogeneous fraction of cells forming a robust cellular ecosystem and serving as a novel and valuable source of point-of-care autologous cell therapy, providing an easy-to-access population that we hypothesize can mediate repair through 'bi-directional' communication in response to pathological cues. We provide the first comprehensive review of all pre-clinical and clinical findings available to date and highlight major challenges and future directions. There is a greater medical and economic urgency to innovate and develop novel cellular therapy solutions that enable the repair and regeneration of neuronal tissue that has undergone irreversible and permanent damage.

Polymeric nanoparticles for dopamine and levodopa replacement in Parkinson's disease

As the world's population ages, the incidence of Parkinson's disease (PD), the second most common neurological ailment, keeps increasing. It is estimated that 1% of the global population over the age of 60 has the disease. The continuous loss of dopaminergic neurons and the concomitant brain depletion of dopamine levels represent the hallmarks of PD. As a result, current PD therapies primarily target dopamine or its precursor (levodopa). Therapeutic approaches that aim to provide an exogenous source of levodopa or dopamine are hindered by their poor bioavailability and the blood-brain barrier. Nevertheless, the fabrication of many polymeric nanoparticles has been exploited to deliver several drugs inside the brain. In addition to a brief introduction of PD and its current therapeutic approaches, this review covers novel polymeric nanoparticulate drug delivery systems exploited lately for dopamine and levodopa replacement in PD.

Novel cudraisoflavone J derivatives as potent neuroprotective agents for the treatment of Parkinson's disease via the activation of Nrf2/HO-1 signaling

Parkinson's disease (PD) is a neurodegenerative disorder that causes uncontrollable movements. Although many breakthroughs in PD therapy have been accomplished, there is currently no cure for PD, and only trials to relieve symptoms have been evaluated. Recently, we reported the total synthesis of cudraisoflavone J and its chiral isomers [Lu et al., J. Nat. Prod. 2021, 84, 1359]. In this study, we designed and synthesized a series of novel cudraisoflavone J derivatives and evaluated their neuroprotective activities in neurotoxin-treated PC12 cells. Among these compounds, difluoro-substituted derivative (13m) and prenylated derivative (24) provided significant protection to PC12 cells against toxicity induced by 6-hydroxydopamine (6-OHDA) or rotenone. Both derivatives inhibited 6-OHDA- or rotenone-induced production of reactive oxygen species and partially attenuated lipid peroxidation in rat brain homogenates, indicating their antioxidant properties. They also increased the expression of the antioxidant enzyme, heme oxygenase (HO)-1, and enhanced the nuclear translocation of Nrf2, the transcription factor that regulates the expression of antioxidant proteins. The neuroprotective effects of 13m and 24 were eliminated by Zn(II)-protoporphyrin IX, an HO-1 inhibitor, demonstrating the critical role of HO-1 in their actions. Moreover, upregulation of HO-1 was abolished by nuclear factor erythroid 2-related factor (Nrf2) knockdown, verifying that Nrf2 is an upstream regulator of HO-1. Compounds 13m and 24 triggered phosphorylation of ERK1/2, JNK, and Akt. Most importantly, 13m- and 24-induced enhancement of Nrf2 translocation and HO-1 expression was reversed by U0126 (an ERK inhibitor), SP600125 (a JNK inhibitor), and LY294002 (an Akt inhibitor). Collectively, our results show that compounds 13m and 24 exert neuroprotective and antioxidant effects through the Nrf2/HO-1 pathway mediated by phosphorylation of ERK1/2, JNK, or Akt in PC12 cells. Based on our findings, both derivatives could serve as potential therapeutic candidates for the neuroprotective treatment of PD.

«One Small Step for Mouse»: High CO2 Inhalation as a New Therapeutic Strategy for Parkinson's Disease

Parkinson's disease (PD) is a ubiquitous neurodegenerative disorder for which no effective treatment strategies are available. Existing pharmacotherapy is aimed only at correcting symptoms and slowing the progression of the disease, mainly by replenishing dopamine deficiency. It is assumed that mitochondrial dysfunction plays a key role in the pathogenesis of PD. It has been suggested that activation of specific degradation of damaged mitochondria (mitophagy) may prevent cell death. An almost exclusive way to initiate mitophagy is acidification of intracellular pH. We attempted to implement transient brain acidification using two experimental therapy strategies: forced moderate physical activity and high CO2 inhalation. The beneficial effects of CO2 supplementation on behavioral aspects were demonstrated in a rotenone-induced PD model. Mice treated with CO2 restored their exploratory behavior and total locomotor activity lost after rotenone administration. Additionally, this treatment enabled the removal of impaired coordination. We have illustrated this therapeutic strategy using histological studies of brain sections to confirm the survival of nigrostriatal areas. These findings suggest that high CO2 inhalation presumably initiates mitophagy via transient brain acidification, and can treat PD-like symptoms in a rodent rotenone model of PD.

Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease

An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca²⁺ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.

Drug reprofiling history and potential therapies against Parkinson's disease

Given the high whittling down rates, high costs, and moderate pace of new medication, revelation, and improvement, repurposing "old" drugs to treat typical and uncommon illnesses is progressively becoming an appealing proposition. Drug repurposing is the way toward utilizing existing medications in treating diseases other than the purposes they were initially designed for. Faced with scientific and economic challenges, the prospect of discovering new medication indications is enticing to the pharmaceutical sector. Medication repurposing can be used at various stages of drug development, although it has shown to be most promising when the drug has previously been tested for safety. We describe strategies of drug repurposing for Parkinson's disease, which is a neurodegenerative condition that primarily affects dopaminergic neurons in the substantia nigra. We also discuss the obstacles faced by the repurposing community and suggest new approaches to solve these challenges so that medicine repurposing can reach its full potential.

Video-Based Hand Movement Analysis of Parkinson Patients before and after Medication Using High-Frame-Rate Videos and MediaPipe

Tremor is one of the common symptoms of Parkinson's disease (PD). Thanks to the recent evolution of digital technologies, monitoring of PD patients' hand movements employing contactless methods gained momentum. Objective: We aimed to quantitatively assess hand movements in patients suffering from PD using the artificial intelligence (AI)-based hand-tracking technologies of MediaPipe. Method: High-frame-rate videos and accelerometer data were recorded from 11 PD patients, two of whom showed classical Parkinsonian-type tremor. In the OFF-state and 30 Minutes after taking their standard oral medication (ON-state), video recordings were obtained. First, we investigated the frequency and amplitude relationship between the video and accelerometer data. Then, we focused on quantifying the effect of taking standard oral treatments. Results: The data extracted from the video correlated well with the accelerometer-based measurement system. Our video-based approach identified the tremor frequency with a small error rate (mean absolute error 0.229 (±0.174) Hz) and an amplitude with a high correlation. The frequency and amplitude of the hand movement before and after medication in PD patients undergoing medication differ. PD Patients experienced a decrease in the mean value for frequency from 2.012 (±1.385) Hz to 1.526 (±1.007) Hz and in the mean value for amplitude from 8.167 (±15.687) a.u. to 4.033 (±5.671) a.u. Conclusions: Our work achieved an automatic estimation of the movement frequency, including the tremor frequency with a low error rate, and to the best of our knowledge, this is the first paper that presents automated tremor analysis before/after medication in PD, in particular using high-frame-rate video data.

Emerging role of psychosis in Parkinson's disease: From clinical relevance to molecular mechanisms

Parkinson’s disease (PD) is the second most common neurodegenerative disease. Psychosis is one of the common psychiatric presentations in the natural course of PD. PD psychosis is an important non-motor symptom, which is strongly correlated with a poor prognosis. Increasing attention is being given to PD psychosis. In this opinion review, we summarized and analyzed the identification, screening, epidemiology, mechanisms, risk factors, and therapeutic approaches of PD psychosis based on the current clinical evidence. PD psychosis tends to have a negative effect on patients' quality of life and increases the burden of family caregiving. Screening and identification in the early stage of disease is crucial for establishing tailored therapeutic strategies and predicting the long-term outcome. Development of PD psychosis is believed to involve a combination of exogenous and endogenous mechanisms including imbalance of neurotransmitters, structural and network changes, genetic profiles, cognitive impairment, and antiparkinsonian medications. The therapeutic strategy for PD psychosis includes reducing or ceasing the use of dopaminergic drug, antipsychotics, cholinesterase inhibitors, and non-pharmacological interventions. Ongoing clinical trials are expected to provide new insights for tailoring therapy for PD psychosis. Future research based on novel biomarkers and genetic factors may help inform individualized therapeutic strategies.

Boosting caffeic acid performance as antioxidant and monoamine oxidase B/catechol-O-methyltransferase inhibitor

Increased oxidative stress (OS) and depletion of nigrostriatal dopamine (DA) are closely linked to the neurodegeneration observed in Parkinson's Disease (PD). Caffeic acid (CA)-based antioxidants were developed, and their inhibitory activities towards monoamine oxidases (MAOs) and catechol O-methyltransferases (COMT) were screened. The results showed that the incorporation of an extra double bond maintained or even boosted the antioxidant properties of CA. α-CN derivatives displayed redox potentials (E_p) similar to CA (1) and inhibited hMAO-B with low μM IC₅₀ values. Moreover, catechol amides acted as MB-COMT inhibitors, showing IC₅₀ values within the low μM range. In general, CA derivatives presented safe cytotoxicity profiles at concentrations up to 10 μM. The formation of reactive oxygen species (ROS) induced by CA derivatives may be underlying the cytotoxic effects observed at higher concentrations. Catechol amides 3-6, 8-11 at 10 μM protected cells against oxidative damage. Compounds 3 and 8 were predicted to cross the blood-brain barrier (BBB) by passive diffusion. In summary, we report for the first time BBB-permeant CA-based multitarget lead compounds that may restore DAergic neurotransmission (dual hMAO-B/MB-COMT inhibition) and prevent oxidative damage. The data represents a groundbreaking advancement towards the discovery of the next generation of new drugs for PD.

Prescription Pattern of Monoamine Oxidase B Inhibitors Combined with Levodopa: A Retrospective Observational Analysis of Italian Healthcare Administrative Databases

BACKGROUND

Parkinson's disease is still incurable, and several factors are considered when defining pharmacological therapy.

OBJECTIVE

The aim of this study was to describe the prescription pattern of monoamine oxidase B inhibitors (MAO-BIs) marketed in Italy (selegiline, rasagiline, safinamide) as an add-on to levodopa among new users of MAO-BIs, from the perspective of the Italian National Health Service.

PATIENTS AND METHODS

Through cross-linkage of administrative healthcare data in the Ricerca e Salute (ReS) database, adults with a supply of one or more MAO-BIs in 2017, and with no other MAO-BI use since 2013, were selected. Levodopa had to be supplied within 30 days before/after the MAO-BI. The incidence, use, sex, age, comorbidities, 2-year prescription patterns (i.e., switches, proportion of treated patients per semester/year, mean daily milligrams/monthly tablets supplied, discontinuation, change to other anti-Parkinson drug) of patients taking MAO-BIs were provided.

RESULTS

In 2017, 1059 new users received an MAO-BI (incidence 22.6 × 100,000 adults) combined with levodopa: 502 subjects (10.7 × 100,000) were treated with selegiline, 161 (3.4 × 100,000) were treated with rasagiline, and 396 (8.4 × 100,000) were treated with safinamide. The cohorts mainly consisted of males with a median age of ≥ 74 years. Treatment incidences increased with age. Switches occurred in 18.0%, 11.0%, and 4.3% of the selegiline, rasagiline, and safinamide cohorts, respectively. Most of the patients switching from selegiline/safinamide changed to rasagiline, while most of the patients switching from rasagiline changed to safinamide. From the first to second years, patient numbers reduced by ≤ 50%, and the daily milligrams/monthly tablets slightly increased. Six-month discontinuation occurred in > 50% of all cohorts, and ≥ 65% of discontinuing patients changed to another anti-Parkinson drug.

CONCLUSIONS

This analysis described the heterogeneous use of MAO-BIs as an add-on to levodopa in Italy. Further clinical trials and real-world studies are encouraged to update the few existing guidelines and to align clinical practice strategies.

Rasagiline as Adjunct to Levodopa for Treatment of Parkinson’s Disease: A Systematic Review and Meta-Analysis

Background

Rasagiline is a selective, irreversible monoamine oxidase type B inhibitor used as monotherapy in early Parkinson's disease and as an adjunct therapy to levodopa in Parkinson's disease with motor fluctuations.

Objectives

This meta-analysis aimed to provide updated evidence on the efficacy for motor and nonmotor symptoms and the safety of rasagiline/levodopa versus levodopa in patients with Parkinson's disease experiencing motor fluctuations.

Methods

A systematic literature search was conducted (January 18-19, 2021) using PubMed, Cochrane Library, EMBASE, Web of Science, and Google Scholar to identify randomized controlled trials comparing rasagiline/levodopa versus placebo/levodopa in patients with Parkinson's disease experiencing motor fluctuations. Outcomes included change in wearing-off time, Unified Parkinson's Disease Rating Scale (UPDRS)/Movement Disorder Society-UPDRS (MDS-UPDRS) II and III scores, treatment-emergent adverse events (TEAEs), and Parkinson's Disease Questionnaire (PDQ-39) summary index score. A random effect model was used to estimate the treatment effects.

Results

Six studies were included (1912 patients). Significant improvements in wearing-off time (standardized mean difference [SMD]: −0.50, 95% confidence interval [CI]: –0.92 to –0.09, p = 0.002), levodopa dosage (SMD: −0.18, 95% CI: −0.35 to –0.01, p = 0.041), UPDRS/MDS-UPDRS II (SMD: −0.39, 95% CI: −0.52 to –0.25, p < 0.0001), UPDRS/MDS-UPDRS III (SMD: −0.30, 95% CI: −0.44 to –0.16, p < 0.0001), and PDQ-39 summary index score (SMD: –0.21, 95% CI: –0.37 to –0.04, p = 0.013) were observed with rasagiline/levodopa versus placebo/levodopa. The incidence of TEAEs did not differ between treatments (risk ratio: 1.13, 95% CI: 0.98–1.30, p = 0.093).

Conclusions

This meta-analysis further indicated the superiority of rasagiline/levodopa in improving motor and nonmotor symptoms of Parkinson's disease, with a similar safety profile to that of levodopa in Parkinson's disease with motor fluctuations.

Inosine in Neurodegenerative Diseases: From the Bench to the Bedside

Neurodegenerative diseases, such as Alzheimer′s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), currently represent major unmet medical needs. Therefore, novel therapeutic strategies are needed in order to improve patients’ quality of life and prognosis. Since oxidative stress can be strongly involved in neurodegenerative diseases, the potential use of inosine, known for its antioxidant properties, in this context deserves particular attention. The protective action of inosine treatment could be mediated by its metabolite urate. Here, we review the current preclinical and clinical studies investigating the use of inosine in AD, PD, ALS, and MS. The most important properties of inosine seem to be its antioxidant action and its ability to raise urate levels and to increase energetic resources by improving ATP availability. Inosine appears to be generally safe and well tolerated; however, the possible formation of kidney stones should be monitored, and data on its effectiveness should be further explored since, so far, they have been controversial. Overall, inosine could be a promising potential strategy in the management of neurodegenerative diseases, and additional studies are needed in order to further investigate its safety and efficacy and its use as a complementary therapy along with other approved drugs.

Effect of Zhan Zhuang Qigong on upper limb static tremor and aerobic exercise capacity in patients with mild-to-moderate Parkinson's disease: study protocol for a randomised controlled trial

INTRODUCTION

Currently, the first choice for the clinical treatment of static tremor in Parkinson's disease (PD) is drug therapy, however side effects are common. In recent years, the effects of physical therapy on PD has become a serious research focus. Studies have indicated that aerobic and resistance exercises alleviate PD movement disorders and improve aerobic capacity, but the effects of Qigong on PD static tremor and aerobic capacity remain unknown.

METHODS AND ANALYSIS

OBJECTIVE: To observe the effects of Zhan Zhuang Qigong on upper limb static tremor and aerobic capacity in patients with PD, we established a rigorous randomised, parallel-controlled, assignment hidden, evaluator-blinded protocol.

METHODS

Seventy-two patients with PD, at the Affiliated Hospital of Shandong University of Traditional Chinese Medicine, were recruited and randomly divided into a control (n=36) and experimental group (n=36). The intervention group received conventional medicine plus Zhan Zhuang Qigong exercises five times a week at 30 min each time, over an 8-week period. The long-term effects of Zhan Zhuang Qigong on PD was investigated after the intervention. Phyphox APP, CRST, CPET, UPDRS(II, III) were used to evaluate tremor, aerobic capacity, and motor function in groups.

DISCUSSION

We are investigating the effects of Zhan Zhuang Qigong on upper limb static tremor and aerobic capacity in patients with PD. If positive are identified, they will add a new research direction and evidence for the clinical exploration of exercise therapy for PD.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of Shandong University of Traditional Chinese Medicine (Approval Number: 2021-025-KY). The Committee will be informed of any changes to the trial protocol, such as intervention intensity, outcome indicators and data collection. Study results will be presented as a paper at an international conference or in a journal.

TRIAL REGISTRATION NUMBER

ChiCTR2100053529.

Binding of the Dual-Action Anti-Parkinsonian Drug AG-0029 to Dopamine D2 and Histamine H3 Receptors: A PET Study in Healthy Rats

Introduction: Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor dysfunction and a diverse range of nonmotor symptoms. Functional relationships between the dopaminergic and histaminergic systems suggest that dual-action pharmaceuticals like AG-0029 (D2/D3 agonist/H3 antagonist) could ameliorate both the motor and cognitive symptoms of PD. The current study aimed to demonstrate the interaction of AG-0029 with its intended targets in the mammalian brain using positron emission tomography (PET). Methods: Healthy male Wistar rats were scanned with a small-animal PET camera, using either the dopamine D2/D3 receptor ligand [11C]raclopride or the histamine H3 receptor ligand [11C]GSK-189254, before and after treatment with an intravenous, acute, single dose of AG-0029. Dynamic [11C]raclopride PET data (60 min duration) were analyzed using the simplified reference tissue model 2 (SRTM2) with cerebellum as reference tissue and the nondisplaceable binding potential as the outcome parameter. Data from dynamic [11C]GSK-189254 scans (60 min duration) with arterial blood sampling were analyzed using Logan graphical analysis with the volume of distribution (VT) as the outcome parameter. Receptor occupancy was estimated using a Lassen plot. Results: Dopamine D2/3 receptor occupancies in the striatum were 22.6 ± 18.0 and 84.0 ± 3.5% (mean ± SD) after administration of 0.1 and 1 mg/kg AG-0029, respectively. In several brain regions, the VT values of [11C]GSK-189254 were significantly reduced after pretreatment of rats with 1 or 10 mg/kg AG-0029. The H3 receptor occupancies were 11.9 ± 8.5 and 40.3 ± 11.3% for the 1 and 10 mg/kg doses of AG-0029, respectively. Conclusions: Target engagement of AG-0029 as an agonist at dopamine D2/D3 receptors and an antagonist at histamine H3 receptors could be demonstrated in the rat brain with [11C]raclopride and [11C]GSK-189254 PET, respectively. The measured occupancy values reflect the previously reported high (subnanomolar) affinity of AG-0029 to D2/D3 and moderate (submicromolar) affinity to H3 receptors.

Neuroprotective approaches to halt Parkinson's disease progression

One of the most significant threats in Parkinson's disease (PD) is neurodegeneration. Neurodegeneration at both nigral as well as non-nigral regions of the brain is considered responsible for disease progression in PD. The key factors that initiate neurodegeneration are oxidative stress, neuroinflammation, mitochondrial complex-1 inhibition, and abnormal α-synuclein (SNCA) protein aggregations. Nigral neurodegeneration results in motor symptoms (tremor, bradykinesia, rigidity, shuffling gait, and postural instability) whereas; non-nigral neurodegeneration is responsible for non-motor symptoms (depression, cognitive dysfunctions, sleep disorders, hallucination, and psychosis). The available therapies for PD aim at increasing dopamine levels. The medications such as Monoamine oxidase B (MAO-B) inhibitors, catechol o-methyltransferase (COMT) inhibitors, Dopamine precursor (Levodopa), dopamine agonists, and dopamine reuptake inhibitors drastically improve the motor symptoms and quality of life only in the early stages of the disease. However, dopa resistant motor symptoms (abnormality in posture, speech impediment, gait, and balance problems), dopa resistant non-motor signs (sleep problems, autonomic dysfunction, mood, and cognitive impairment, pain), and drug-related side effects (motor fluctuations, psychosis, and dyskinesias) are considered responsible for the failure of these therapies. Further, none of the treatments, alone or in combination, are capable of halting the disease progression in the long run. Therefore, there is a need to develop safe and efficient neuroprotective agents, which can slow or stop the disease progression for the better management of PD. In this review, an effort has been made to discuss the various mechanisms responsible for progressive neurodegeneration (disease progression) in PD and also multiple strategies available for halting disease progression.