L-dopa therapy for Parkinson's disease: past, present, and future

T-type calcium channels attenuate anxiety in MPTP-treated mice through modulating burst firing of dopaminergic neuron

T-type calcium channel(T-VGCC) is a critical voltage-gated channel extensively involved in signal transmission and functional regulation of the nervous system. Recent studies have shown that T-VGCC exhibits low-threshold activation properties and generate high-frequency firing, making it essential in neuronal firing patterns. However, the effects of T-VGCC on dopaminergic (DAergic) neurons in the substantia nigra (SN) remain unclear. In the present study, we constructed Parkinson's disease (PD) model mice using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and we found that intracerebroventricular injection of T-VGCC blocker (Mibefradil) alleviates the anxiety behavior and the extent of damage to DAergic neurons in MPTP-treated mice. In vivo electrophysiological experiments demonstrated that T-VGCC directly regulates the burst firing of DAergic neurons. Correlation analysis suggested a strong association between DAergic neuron burst firing and anxiety-like behaviors in mice. Notably, calcium imaging experiments revealed that inhibiting T-VGCC significantly decreased calcium signal levels in DAergic neurons of MPTP-treated mice. To sum up, our research results for the first time reveal the crucial role that the burst firing of DAergic neurons in the SN mediated by T-VGCC plays in regulating anxiety behavior in PD. This discovery offers a potential therapeutic target for PD patients with anxiety.

L-DOPA Induces Spatially Discrete Changes in Gene Expression in the Forebrain of Mice with a Progressive Loss of Dopaminergic Neurons

L-3,4-Dihydroxyphenylalanine (L-DOPA) is effective at alleviating motor impairments in Parkinson's disease (PD) patients but has mixed effects on nonmotor symptoms and causes adverse effects after prolonged treatment. Here, we analyzed the spatial profile of L-DOPA-induced gene expression in the forebrain of mice with an inducible progressive loss of dopaminergic neurons (the TIF-IADATCreERT2 strain), with a focus on the similarities and differences in areas relevant to different PD symptoms. The animals received a 14-day L-DOPA treatment, and 1 h after the final drug injection, a spatial transcriptome analysis was performed on coronal forebrain sections. A total of 121 genes were identified as being regulated by L-DOPA. We found that the treatment had widespread effects extending beyond the primary areas involved in dopamine-dependent movement control. An unsupervised clustering analysis of the transcripts recapitulated the forebrain anatomy and indicated both ubiquitous and region-specific effects on transcription. The changes were most pronounced in layers 2/3 and 5 of the dorsal cortex and the dorsal striatum, where a robust increase in the abundance of activity-regulated transcripts, including Fos, Egr1, and Junb, was observed. Conversely, transcripts with a decreased abundance, e.g., Plekhm2 or Pgs1, were identified primarily in the piriform cortex, the adjacent endopiriform nucleus, and the claustrum. Taken together, our spatial analysis of L-DOPA-induced alterations in gene expression reveals the anatomical complexity of treatment effects, identifying novel genes affected by the drug, as well as molecular activation in brain areas relevant to the nonmotor symptoms of PD.

The effect of supplementation with prebiotic fiber on the gut microbiota of a group of older people with Parkinson's disease from the city of Santiago de Chile. A pilot study

Introduction

Introduction: Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. It has been demonstrated that there is a correlation between the increase in bacterial abundance and the severity of certain symptoms associated with PD. Aim: the aim of this pilot study was to analyze the effect of supplementation with prebiotic fiber on the gut microbiota (GM) and nutritional status of elderly volunteers with Parkinson's disease. Methodology: this is a pilot study of pre and post intervention with prebiotic fiber. All subjects involved were volunteers with PD, who were given nutritional counseling and gut microbiota measured on time cero and after 30 days of prebiotic fiber intervention. Results: a statistically significant difference was found in calf circumference (p 0.0422) after the intervention with prebiotic fiber. GM analyses show an initial difference in gut bacterial abundance of older people with PD and people without PD. Furthermore, our results showed a difference in bacterial families and genera after the supplementation with prebiotic fiber. in addition, we found a statistically significant difference in the val-ue of circumference calf and a trend in the improvement of body weight, Body mass index (BMI), neck circumference, arm circumference, brachial area, and Diet Quality Questionnaire (DQQ) for older adults. Conclusion: supplementation with 20 g of prebiotic fiber for 30 days could modify the intestinal microbiota, reducing bacterial genera and phylum that are abundant in Park-inson's disease, such as Verrucomicrobia. Therefore, the use of prebiotic fiber could represent an alternative to improve intestinal health and nutritional status of people with Parkinson's disease.

Spinal Cord Stimulation Modulates Rat Cortico-Basal Ganglia Locomotor Circuit

OBJECTIVE

The cortico-basal ganglia circuit is crucial to understanding locomotor behavior and movement disorders. Spinal cord stimulation modulates that circuit, which is a promising approach to restoring motor functions. However, the effects of electrical spinal cord stimulation in the healthy brain motor circuit in pre- and postgait are poorly understood. Thus, this report aims to evaluate, through electrophysiological analyses, the dynamic spectral features of motor networks underlying locomotor initiation with spinal cord stimulation.

MATERIALS AND METHODS

Wistar male rats underwent spinal cord stimulation (current 30-150 μA, frequency 100, 333, and 500 Hz) with the electrophysiological recording of the caudate and putamen nuclei, primary and secondary motor cortices, and primary somatosensory cortex. Video tracking recorded treadmill locomotion and extracted the motor planning and gait initiation.

RESULTS

Spectral analysis of segments of gait initiation (pre- and postgait), with stimulation off, showed increased low-frequency activity. Postgait initiation showed increased alpha and beta rhythms and decreased delta rhythm with the stimulation off. Overall, the stimulation frequencies reduced alpha and beta rhythms in all brain areas during movement initiation. Regarding movement planning, such an effect was observed in the sensorimotor area, comprising the delta and alpha rhythms.

CONCLUSION

This study showed a short-term effect of spinal cord stimulation on the brain areas of the motor circuit, suggesting possible facilitation of movement planning and starting through neuromodulation. Thus, the electrophysiological characterization of this study may contribute to understanding basal ganglia networks and developing new approaches to treat movement disorders in the gait initiation phase.

Neuroprotective and Neurite Outgrowth Stimulating Effects of New Low-Basicity 5-HT7 Receptor Agonists: In Vitro Study in Human Neuroblastoma SH-SY5Y Cells

There is some evidence that the serotonin receptor subtype 7 (5-HT7) could be new therapeutic target for neuroprotection. The aim of this study was to compare the neuroprotective and neurite outgrowth potential of new 5-HT7 receptor agonists (AH-494, AGH-238, AGH-194) with 5-CT (5-carboxyamidotryptamine) in human neuroblastoma SH-SY5Y cells. The results revealed that 5-HT7 mRNA expression was significantly higher in retinoic acid (RA)-differentiated cells when compared to undifferentiated ones and it was higher in cell cultured in neuroblastoma experimental medium (DMEM) compared to those placed in neuronal (NB) medium. Furthermore, the safety profile of compounds was favorable for all tested compounds at concentration used for neuroprotection evaluation (up to 1 μM), whereas at higher concentrations (above 10 μM) the one of the tested compounds, AGH-194 appeared to be cytotoxic. While we observed relatively modest protective effects of 5-CT and AH-494 in UN-SH-SY5Y cells cultured in DMEM, in UN-SH-SY5Y cells cultured in NB medium we found a significant reduction of H2O2-evoked cell damage by all tested 5-HT7 agonists. However, 5-HT7-mediated neuroprotection was not associated with inhibition of caspase-3 activity and was not observed in RA-SH-SY5Y cells exposed to H2O2. Furthermore, none of the tested 5-HT7 agonists altered the damage induced by 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenylpyridinium ion (MPP +) and doxorubicin (Dox) in UN- and RA-SH-SY5Y cells cultured in NB. Finally we showed a stimulating effect of AH-494 and AGH-194 on neurite outgrowth. The obtained results provide insight into neuroprotective and neurite outgrowth potential of new 5-HT7 agonists.

A Computational Model of Deep Brain Stimulation for Parkinson's Disease Tremor and Bradykinesia

Parkinson's disease (PD) is a progressive neurological disorder that is typically characterized by a range of motor dysfunctions, and its impact extends beyond physical abnormalities into emotional well-being and cognitive symptoms. The loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) leads to an array of dysfunctions in the functioning of the basal ganglia (BG) circuitry that manifests into PD. While active research is being carried out to find the root cause of SNc cell death, various therapeutic techniques are used to manage the symptoms of PD. The most common approach in managing the symptoms is replenishing the lost dopamine in the form of taking dopaminergic medications such as levodopa, despite its long-term complications. Another commonly used intervention for PD is deep brain stimulation (DBS). DBS is most commonly used when levodopa medication efficacy is reduced, and, in combination with levodopa medication, it helps reduce the required dosage of medication, prolonging the therapeutic effect. DBS is also a first choice option when motor complications such as dyskinesia emerge as a side effect of medication. Several studies have also reported that though DBS is found to be effective in suppressing severe motor symptoms such as tremors and rigidity, it has an adverse effect on cognitive capabilities. Henceforth, it is important to understand the exact mechanism of DBS in alleviating motor symptoms. A computational model of DBS stimulation for motor symptoms will offer great insights into understanding the mechanisms underlying DBS, and, along this line, in our current study, we modeled a cortico-basal ganglia circuitry of arm reaching, where we simulated healthy control (HC) and PD symptoms as well as the DBS effect on PD tremor and bradykinesia. Our modeling results reveal that PD tremors are more correlated with the theta band, while bradykinesia is more correlated with the beta band of the frequency spectrum of the local field potential (LFP) of the subthalamic nucleus (STN) neurons. With a DBS current of 220 pA, 130 Hz, and a 100 microsecond pulse-width, we could found the maximum therapeutic effect for the pathological dynamics simulated using our model using a set of parameter values. However, the exact DBS characteristics vary from patient to patient, and this can be further studied by exploring the model parameter space. This model can be extended to study different DBS targets and accommodate cognitive dynamics in the future to study the impact of DBS on cognitive symptoms and thereby optimize the parameters to produce optimal performance effects across modalities. Combining DBS with rehabilitation is another frontier where DBS can reduce symptoms such as tremors and rigidity, enabling patients to participate in their therapy. With DBS providing instant relief to patients, a combination of DBS and rehabilitation can enhance neural plasticity. One of the key motivations behind combining DBS with rehabilitation is to expect comparable results in motor performance even with milder DBS currents.

Catecholamines and Parkinson's disease: tyrosine hydroxylase (TH) over tetrahydrobiopterin (BH4) and GTP cyclohydrolase I (GCH1) to cytokines, neuromelanin, and gene therapy: a historical overview

The author identified the genes and proteins of human enzymes involved in the biosynthesis of catecholamines (dopamine, norepinephrine, epinephrine) and tetrahydrobiopterin (BH4): tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC), dopamine β-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), and GTP cyclohydrolase I (GCH1). In Parkinson's disease (PD), the activities and levels of mRNA and protein of all catecholamine-synthesizing enzymes are decreased, especially in dopamine neurons in the substantia nigra. Hereditary GCH1 deficiency results in reductions in the levels of BH4 and the activities of TH, causing decreases in dopamine levels. Severe deficiencies in GCH1 or TH cause severe decreases in dopamine levels leading to severe neurological symptoms, whereas mild decreases in TH activity in mild GCH1 deficiency or in mild TH deficiency result in only modest reductions in dopamine levels and symptoms of DOPA-responsive dystonia (DRD, Segawa disease) or juvenile Parkinsonism. DRD is a treatable disease and small doses of L-DOPA can halt progression. The death of dopamine neurons in PD in the substantia nigra may be related to (i) inflammatory effect of extra neuronal neuromelanin, (ii) inflammatory cytokines which are produced by activated microglia, (iii) decreased levels of BDNF, and/or (iv) increased levels of apoptosis-related factors. This review also discusses progress in gene therapies for the treatment of PD, and of GCH1, TH and AADC deficiencies, by transfection of TH, AADC, and GCH1 via adeno-associated virus (AAV) vectors.

MAO inhibiting phytochemicals from the roots of Glycyrrhiza glabra L

Glycyrrhizin, a natural compound that is substantially present in Glycyrrhiza glabra L. (Gg) root. Monoamine oxidase B (MAOB) inhibitor is used for the treatment of several important neuropsychological diseases like Parkinson's disease. Gg is known to possess psychoactive properties which relates to its MAO inhibitory potential. This study sought to determine the MAO inhibition property of glycyrrhizin from Gg root extract. The Aqueous extract containing glycyrrhizin was isolated from the root of Gg and characterized using TLC, HPLC, and LC-MS techniques. In silico docking was conducted using Extra precision Glide 2018, Schrödinger docking suite. In addition, the pharmacokinetic properties of the compounds were predicted using SwissADME. The binding energies of the glycyrrhizin correlated well with their in vitro MAO inhibitory potential. Glycyrrhizin exhibited potent inhibitory activity towards MAOB whereas, an aqueous extract of Gg root inhibits both A and B forms of MAO enzyme. Further, molecular docking and molecular dynamics simulation showed that liquiritigenin and methoxyglabridin showed higher stability than other inhibitor compounds from the Gg root extract. These observations suggest that the phytochemicals from the Gg root extract have potent MAO inhibition properties, which can be exploited for the treatment of neurodegenerative disorders.Communicated by Ramaswamy H. Sarma.

Immobilization of human tyrosine hydroxylase onto magnetic nanoparticles - A novel formulation of a therapeutic enzyme

Human tyrosine hydroxylase (hTH) has key role in the production of catecholamine neurotransmitters. The structure, function and regulation of hTH has been extensively researched area and the possibility of enzyme replacement therapy (ERT) involving hTH through nanocarriers has been raised as well. However, our understanding on how hTH may interact with nanocarriers is still lacking. In this work, we attempted to investigate the immobilization of hTH on magnetic nanoparticles (MNPs) with various surface linkers in quantitative and mechanistic detail. Our results showed that the activity of hTH was retained after immobilization via secondary and covalent interactions as well. The colloidal stability of hTH could be also enhanced proved by Dynamic light scattering and Zeta potential analysis and a homogenous enzyme layer could be achieved, which was investigated by Raman mapping. The covalent attachment of hTH on MNPs via aldehyde or epoxy linkers provide irreversible immobilization and 38.1 % and 16.5 % recovery (ER). The hTH-MNPs catalyst had 25 % ER in average in simulated nasal electrolyte solution (SNES). This outcome highlights the relevance of immobilization applying MNPs as a potential formulation tool of sensitive therapeutic enzymes offering new opportunities for ERT related to neurodegenerative disorders.

Autophagy-associated non-coding RNAs: Unraveling their impact on Parkinson's disease pathogenesis

BACKGROUND

Parkinson's disease (PD) is a degenerative neurological condition marked by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta. The precise etiology of PD remains unclear, but emerging evidence suggests a significant role for disrupted autophagy-a crucial cellular process for maintaining protein and organelle integrity.

METHODS

This review focuses on the role of non-coding RNAs (ncRNAs) in modulating autophagy in PD. We conducted a comprehensive review of recent studies to explore how ncRNAs influence autophagy and contribute to PD pathophysiology. Special attention was given to the examination of ncRNAs' regulatory impacts in various PD models and patient samples.

RESULTS

Findings reveal that ncRNAs are pivotal in regulating key processes associated with PD progression, including autophagy, α-synuclein aggregation, mitochondrial dysfunction, and neuroinflammation. Dysregulation of specific ncRNAs appears to be closely linked to these pathogenic processes.

CONCLUSION

ncRNAs hold significant therapeutic potential for addressing autophagy-related mechanisms in PD. The review highlights innovative therapeutic strategies targeting autophagy-related ncRNAs and discusses the challenges and prospective directions for developing ncRNA-based therapies in clinical practice. The insights from this study underline the importance of ncRNAs in the molecular landscape of PD and their potential in novel treatment approaches.

Exploring the therapeutic potential of Rab11: A comprehensive study on its effectiveness in alleviating rotenone-induced molecular pathogenesis of Parkinson's disease in SH-SY5Y cells and its synergistic application with L-DOPA in Drosophila models

Dysfunctional mitophagy contributes to Parkinson's disease (PD) by affecting dopamine-producing neurons. Mutations in parkin and pink1 genes, linked to familial PD, impede the removal of damaged mitochondria. Previous studies suggested Rab11's involvement in mitophagy alongside Parkin and Pink1. Additionally, mitochondria-endoplasmic reticulum contact sites (MERCS) regulate cellular functions, including mitochondrial quality control and calcium regulation. Our study explored whether activating mitophagy triggers the unfolded protein response and ER stress pathway in SH-SY5Y human cells. We induced a PD-like state by exposing undifferentiated SH-SY5Y cells to rotenone, an established PD-inducing agent. This led to reduced Rab11 and PERK- expression while increasing ATP5a, a mitochondrial marker, when Rab11 was overexpressed. Our findings suggest that enhancing endosomal trafficking can mitigate ER stress by regulating mitochondria, rescuing cells from apoptosis. Furthermore, we assessed the therapeutic potential of Rab11, both alone and in combination with L-Dopa, in a Drosophila PD model. In summary, our research underscores the role of mitophagy dysfunction in PD pathogenesis, highlighting Rab11's importance in alleviating ER stress and preserving mitochondrial function. It also provides insights into potential PD management strategies, including the synergistic use of Rab11 and L-Dopa.

Targeting N-Methyl-d-Aspartate Receptors in Neurodegenerative Diseases

N-methyl-d-aspartate receptors (NMDARs) are the main class of ionotropic receptors for the excitatory neurotransmitter glutamate. They play a crucial role in the permeability of Ca2+ ions and excitatory neurotransmission in the brain. Being heteromeric receptors, they are composed of several subunits, including two obligatory GluN1 subunits (eight splice variants) and regulatory GluN2 (GluN2A~D) or GluN3 (GluN3A~B) subunits. Widely distributed in the brain, they regulate other neurotransmission systems and are therefore involved in essential functions such as synaptic transmission, learning and memory, plasticity, and excitotoxicity. The present review will detail the structure, composition, and localization of NMDARs, their role and regulation at the glutamatergic synapse, and their impact on cognitive processes and in neurodegenerative diseases (Alzheimer's, Huntington's, and Parkinson's disease). The pharmacology of different NMDAR antagonists and their therapeutic potentialities will be presented. In particular, a focus will be given on fluoroethylnormemantine (FENM), an investigational drug with very promising development as a neuroprotective agent in Alzheimer's disease, in complement to its reported efficacy as a tomography radiotracer for NMDARs and an anxiolytic drug in post-traumatic stress disorder.

A Small-Molecule Ratiometric Photoacoustic Probe for the High-Spatiotemporal-Resolution Imaging of Copper(II) Dynamics in the Mouse Brain

Copper dysmetabolism is associated with various neurodegenerative disorders, making high-spatiotemporal-resolution imaging of Cu2+ in the brain essential for understanding the underlying pathophysiological processes. Nevertheless, the current probes encounter obstacles in crossing the blood-brain barrier (BBB) and providing high-spatial-resolution in deep tissues. Herein, we present a photoacoustic probe capable of imaging Cu2+ dynamics in the mouse brain with high-spatiotemporal-resolution. The probe demonstrates selective ratiometric and reversible responses to Cu2+ , while also efficiently crossing the BBB. Using the probe as the imaging agent, we successfully visualized Cu2+ in the brain of Parkinson's disease (PD) model mouse with a remarkable micron-level resolution. The imaging results revealed a significant increase in Cu2+ levels in the cerebral cortex as PD progresses, highlighting the close association between Cu2+ alternations in the region and the disease. We also demonstrated that the probe can be used to monitor changes in Cu2+ distribution in the PD model mouse brain during L-dopa intervention. Mechanism studies suggest that the copper dyshomeostasis in the PD mouse brain was dominated by the expression levels of divalent metal transporter 1. The application of our probe in imaging Cu2+ dynamics in the mouse brain offers valuable insights into the copper-related molecular mechanisms underlying neurodegenerative diseases.

Effects of a new selective β3 -adrenoceptor agonist, vibegron, on bladder and urethral function in a rat model of Parkinson's disease

OBJECTIVES

Parkinson's disease caused by the loss of dopaminergic neurons induces not only motor dysfunction but also lower urinary tract dysfunction. Patients with Parkinson's disease have recently been reported to experience both urge urinary incontinence (overactive bladder) and stress urinary incontinence, the latter of which occurs when the pressure of the bladder exceeds that of the urethra. Vibegron is a highly selective novel β3 -adrenoceptor agonist approved for the treatment of overactive bladder. However, how β3 -adrenoceptor agonists affect urethral function remains unclear. In a clinical report, the urethral function of patients with Parkinson's disease was shown to be degraded. The present study aimed to investigate the effects of vibegron on lower urinary tract activity in a rat model of Parkinson's disease.

METHODS

In a rat model of Parkinson's disease induced by unilateral 6-hydroxydopamine injection into the substantia nigra pars compacta, we examined the effects of vibegron on bladder and urethral activity.

RESULTS

Cystometric analysis revealed that, compared with vehicle injection, intravenous injection of 3 mg/kg vibegron significantly increased the inter-contraction interval (p < .05) and reduced voiding pressure (p < .01). However, no significant effects on urethral function were observed.

CONCLUSIONS

The results of the present study provide corroborating evidence that bladder dysfunction is suppressed by the administration of vibegron in Parkinson's disease model rats, confirming that vibegron is effective for treating overactive bladder without further worsening urethral function. These findings may contribute to a better understanding of the mechanisms of β3 -adrenoceptor agonists.

Ferroptosis-related factors in the substantia nigra are associated with Parkinson's disease

Ferroptosis is an iron-dependent, lipid peroxidation-driven cell death pathway, while Parkinson's disease (PD) patients exhibit iron deposition and lipid peroxidation in the brain. Thus, the features of ferroptosis highly overlap with the pathophysiological features of PD. Despite this superficial connection, the possible role(s) of ferroptosis-related (Fr) proteins in dopaminergic neurons and/or glial cells in the substantia nigra (SN) in PD have not been examined in depth. To explore the correlations between the different SN cell types and ferroptosis at the single-cell level in PD patients, and to explore genes that may affect the sensitivity of dopaminergic neurons to ferroptosis, we performed in silico analysis of a single cell RNA sequence (RNA-seq) set (GSE178265) from the Gene Expression Omnibus (GEO) database. We identified differentially expressed genes (DEGs) in the different cell types in the human SN, and proceeded to perform enrichment analysis, constructing a protein-protein interaction network from the DEGs of dopaminergic neurons with the Metascape database. We examined the intersection of Fr genes present in the FerrDb database with DEGs from the GSE178265 set to identify Fr-DEGs in the different brain cells. Further, we identified Fr-DEGs encoding secreted proteins to implicate cell-cell interactions in the potential stimulation of ferroptosis in PD. The Fr-DEGs we identified were verified using the bulk RNA-seq sets (GSE49036 and GSE20164). The number of dopaminergic neurons decreased in the SN of PD patients. Interestingly, non-dopaminergic neurons possessed the fewest DEGs. Enrichment analysis of dopaminergic neurons' DEGs revealed changes in transmission across chemical synapses and ATP metabolic process in PD. The secreted Fr-DEGs identified were ceruloplasmin (CP), high mobility group box 1 (HMGB1) and transferrin (TF). The bulk RNA-seq set from the GEO database demonstrates that CP expression is increased in the PD brain. In conclusion, our results identify CP as a potential therapeutic target to protect dopaminergic neurons by reducing neurons' sensitivity to ferroptosis.

Therapeutic potential of lipid nanosystems for the treatment of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The degeneration of dopaminergic neurons in the midbrain is primarily responsible for the onset of the disease. The major challenge faced in the treatment of PD is the blood-brain barrier (BBB), which impedes the delivery of therapeutics to targeted locations. To address this issue, lipid nanosystems have been used for the precise delivery of therapeutic compounds in anti-PD therapy. In this review, we will discuss the application and clinical significance of lipid nanosystem in delivering therapeutic compounds for anti-PD treatment. These medicinal compounds include ropinirole, apomorphine, bromocriptine, astaxanthin, resveratrol, dopamine, glyceryl monooleate, levodopa, N-3,4-bis(pivaloyloxy)- dopamine and fibroblast growth factor, which have significant potential to treat PD in the early stage. This review, in a nutshell, will pave the way for researchers to develop diagnostic and potential therapeutic approaches using nanomedicine to overcome the challenges posed by the BBB in delivering therapeutic compounds for PD.

Pregnenolone for the treatment of L-DOPA-induced dyskinesia in Parkinson's disease

Growing preclinical and clinical evidence highlights neurosteroid pathway imbalances in Parkinson's Disease (PD) and L-DOPA-induced dyskinesias (LIDs). We recently reported that 5α-reductase (5AR) inhibitors dampen dyskinesias in parkinsonian rats; however, unraveling which specific neurosteroid mediates this effect is critical to optimize a targeted therapy. Among the 5AR-related neurosteroids, striatal pregnenolone has been shown to be increased in response to 5AR blockade and decreased after 6-OHDA lesions in the rat PD model. Moreover, this neurosteroid rescued psychotic-like phenotypes by exerting marked antidopaminergic activity. In light of this evidence, we investigated whether pregnenolone might dampen the appearance of LIDs in parkinsonian drug-naïve rats. We tested 3 escalating doses of pregnenolone (6, 18, 36 mg/kg) in 6-OHDA-lesioned male rats and compared the behavioral, neurochemical, and molecular outcomes with those induced by the 5AR inhibitor dutasteride, as positive control. The results showed that pregnenolone dose-dependently countered LIDs without affecting L-DOPA-induced motor improvements. Post-mortem analyses revealed that pregnenolone significantly prevented the increase of validated striatal markers of dyskinesias, such as phospho-Thr-34 DARPP-32 and phospho-ERK1/2, as well as D1-D3 receptor co-immunoprecipitation in a fashion similar to dutasteride. Moreover, the antidyskinetic effect of pregnenolone was paralleled by reduced striatal levels of BDNF, a well-established factor associated with the development of LIDs. In support of a direct pregnenolone effect, LC/MS-MS analyses revealed that striatal pregnenolone levels strikingly increased after the exogenous administration, with no significant alterations in downstream metabolites. All these data suggest pregnenolone as a key player in the antidyskinetic properties of 5AR inhibitors and highlight this neurosteroid as an interesting novel tool to target LIDs in PD.

Blood-Brain Barrier Permeable Photoacoustic Probe for High-Resolution Imaging of Nitric Oxide in the Living Mouse Brain

Alternations in the brain nitric oxide (NO) homeostasis are associated with a variety of neurodegeneration diseases; therefore, high-resolution imaging of NO in the brain is essential for understanding pathophysiological processes. However, currently available NO probes are unsuitable for this purpose due to their poor ability to cross the blood-brain barrier (BBB) or to image in deep tissues with spatial resolution. Herein, we developed a photoacoustic (PA) probe with BBB crossing ability to overcome this obstacle. The probe shows a highly selective ratiometric response toward NO, which enables the probe to image NO with micron resolution in the whole brain of living mice. Using three-dimensional PA imaging, we demonstrated that the probe could be used to visualize the detailed NO distribution in varying depth cross-sections (0-8 mm) of the living Parkinson's disease (PD) mouse brain. We also investigated the therapeutic properties of natural polyphenols in the PD mouse brain using the probe as an imaging agent and suggested the potential of the probe for screening therapeutic agents. This study provides a promising imaging agent for imaging of NO in the mouse brain with high resolution. We anticipate that these findings may open up new possibilities for understanding the biological functions of NO in the brain and the development of new imaging agents for the diagnosis and treatment of brain diseases.

A Photoacoustic Probe with Blood-Brain Barrier Crossing Ability for Imaging Oxidative Stress Dynamics in the Mouse Brain

Spatiotemporal assessment of the oxidative stress dynamics in the brain is crucial for understanding the molecular mechanism underlying neurodegenerative diseases. However, existing oxidative stress probes have poor blood-brain barrier permeability or poor penetration depth, making them unsuitable for brain imaging. Herein, we developed a photoacoustic probe that enables real-time imaging of oxidative stress dynamics in the mouse brain. The probe not only responds to oxidative stress in a reversible and ratiometric manner, but it can also cross the blood-brain barrier of the mouse brain. Notably, the probe displayed excellent photoacoustic imaging of oxidative stress dynamics in the brains of Parkinson's disease mouse models. In addition, we investigated the antioxidant properties of natural polyphenols in the brain of a Parkinson's disease mouse model using the probe as an imaging agent and suggested the potential of the probe for screening anti-oxidative stress agents.

Mitochondrial dysfunctions, oxidative stress and neuroinflammation as therapeutic targets for neurodegenerative diseases: An update on current advances and impediments

Neurodegenerative diseases (NDs) such as Alzheimer disease (AD), Parkinson disease (PD), and Huntington disease (HD) represent a major socio-economic challenge in view of their high prevalence yet poor treatment outcomes affecting quality of life. The major challenge in drug development for these NDs is insufficient clarity about the mechanisms involved in pathogenesis and pathophysiology. Mitochondrial dysfunction, oxidative stress and inflammation are common pathways that are linked to neuronal abnormalities and initiation of these diseases. Thus, elucidating the shared initial molecular and cellular mechanisms is crucial for recognizing novel remedial targets, and developing therapeutics to impede or stop disease progression. In this context, use of multifunctional compounds at early stages of disease development unclogs new avenues as it acts on act on multiple targets in comparison to single target concept. In this review, we summarize overview of the major findings and advancements in recent years focusing on shared mechanisms for better understanding might become beneficial in searching more potent pharmacological interventions thereby reducing the onset or severity of various NDs.

Drug repurposing: Clemastine fumarate and neurodegeneration

Neurodegenerative diseases have been a weighty problem in elder people who might be stricken with motor or/and cognition defects with lower life quality urging for effective treatment. Drugs are costly from development to market, so that drug repurposing, exploration of existing drugs for novel therapeutic purposes, becomes a wise and popular strategy to raise new treatment options. Clemastine fumarate, different from anti-allergic effect as H1 histamine antagonist, was screened and identified as promising drug for remyelination and autophagy enhancement. Surprisingly, fumarate salt also has similar effect. Hence, whether clemastine fumarate would make a protective impact on neurodegenerative diseases and what contribution fumarate probably makes are intriguing to us. In this review, we summarize the potential mechanism surrounding clemastine fumarate in current literature, and try to distinguish independent or synergistic effect between clemastine and fumarate, aiming to find worthwhile research direction for neurodegeneration diseases.

Garcinia morella extract confers dopaminergic neuroprotection by mitigating mitochondrial dysfunctions and inflammation in mouse model of Parkinson's disease

Dopaminergic neuroprotection is the main interest in designing novel therapeutics against Parkinson's disease (PD). In the process of dopaminergic degeneration, mitochondrial dysfunctions and inflammation are significant. While the existing drugs provide symptomatic relief against PD, a therapy conferring total neuroprotection by targeting multiple degenerative pathways is still lacking. Garcinia morella is a common constituent of Ayurvedic medication and has been used for the treatment of inflammatory disorders. The present study investigates whether administration of G. morella fruit extract (GME) in MPTP mouse model of PD protects against dopaminergic neurodegeneration, including the underlying pathophysiologies, and reverses the motor behavioural abnormalities. Administration of GME prevented the loss of dopaminergic cell bodies in the substantia nigra and its terminals in the corpus striatum of PD mice. Subsequently, reversal of parkinsonian behavioural abnormalities, viz. akinesia, catalepsy, and rearing, was observed along with the recovery of striatal dopamine and its metabolites in the experimental model. Furthermore, reduced activity of the mitochondrial complex II in the nigrostriatal pathway of brain of the mice was restored after the administration of GME. Also, MPTP-induced enhanced activation of Glial fibrillary acidic protein (GFAP) and neuronal nitric oxide synthase (nNOS) in the nigrostriatal pathway, which are the markers of inflammatory stress, were found to be ameliorated on GME treatment. Thus, our study presented a novel mode of dopaminergic neuroprotection by G. morella in PD by targeting the mitochondrial dysfunctions and neuroinflammation, which are considered to be intricately associated with the loss of dopaminergic neurons.

Efficacy of Repetitive Trans-spinal Magnetic Stimulation for Patients with Parkinson's Disease: a Randomised Controlled Trial

We evaluated the effect of repetitive trans-spinal magnetic stimulation (rTSMS) in patients with Parkinson's disease (PD) in a randomised, single-blind study. Participants were hospitalised and administered a single trial of rTSMS or sham treatment 2 days a week for 4 weeks. In addition, all participants underwent rehabilitation 5 days a week for 4 weeks. The primary outcome was the difference between the two groups in the mean change from baseline to post-training in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS). Secondary endpoints included the differences between the two groups in the mean change on the UPDRS part III (motor) score and the Timed Up and Go (TUG) score. Eligible participants were randomly assigned to either the rTSMS group (n = 50) or sham group (n = 50). The between-group difference in mean change in the total UPDRS score was 10.28 (95% confidence interval (CI), 4.42 to 16.13; P = 0.014) immediately after intervention from baseline, 5.04 (95% CI, - 5.41 to 15.50; P = 0.024) 3 months after intervention from baseline and 2.38 (95% CI, 7.18 to 11.85; P = 0.045) 6 months after intervention from baseline. Significant differences between groups in UPDRS part III and TUG scores were maintained more strictly than those in the UPDRS total score. These results strongly indicate that rTSMS promotes the effect of rehabilitation on motor function in patients with PD.

Modulation of Reactive Oxygen Species Homeostasis as a Pleiotropic Effect of Commonly Used Drugs

Age-associated diseases represent a growing burden for global health systems in our aging society. Consequently, we urgently need innovative strategies to counteract these pathological disturbances. Overwhelming generation of reactive oxygen species (ROS) is associated with age-related damage, leading to cellular dysfunction and, ultimately, diseases. However, low-dose ROS act as crucial signaling molecules and inducers of a vaccination-like response to boost antioxidant defense mechanisms, known as mitohormesis. Consequently, modulation of ROS homeostasis by nutrition, exercise, or pharmacological interventions is critical in aging. Numerous nutrients and approved drugs exhibit pleiotropic effects on ROS homeostasis. In the current review, we provide an overview of drugs affecting ROS generation and ROS detoxification and evaluate the potential of these effects to counteract the development and progression of age-related diseases. In case of inflammation-related dysfunctions, cardiovascular- and neurodegenerative diseases, it might be essential to strengthen antioxidant defense mechanisms in advance by low ROS level rises to boost the individual ROS defense mechanisms. In contrast, induction of overwhelming ROS production might be helpful to fight pathogens and kill cancer cells. While we outline the potential of ROS manipulation to counteract age-related dysfunction and diseases, we also raise the question about the proper intervention time and dosage.

Neuromelanin in Parkinson's Disease: Tyrosine Hydroxylase and Tyrosinase

Parkinson's disease (PD) is an aging-related disease and the second most common neurodegenerative disease after Alzheimer's disease. The main symptoms of PD are movement disorders accompanied with deficiency of neurotransmitter dopamine (DA) in the striatum due to cell death of the nigrostriatal DA neurons. Two main histopathological hallmarks exist in PD: cytosolic inclusion bodies termed Lewy bodies that mainly consist of α-synuclein protein, the oligomers of which produced by misfolding are regarded to be neurotoxic, causing DA cell death; and black pigments termed neuromelanin (NM) that are contained in DA neurons and markedly decrease in PD. The synthesis of human NM is regarded to be similar to that of melanin in melanocytes; melanin synthesis in skin is via DOPAquinone (DQ) by tyrosinase, whereas NM synthesis in DA neurons is via DAquinone (DAQ) by tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). DA in cytoplasm is highly reactive and is assumed to be oxidized spontaneously or by an unidentified tyrosinase to DAQ and then, synthesized to NM. Intracellular NM accumulation above a specific threshold has been reported to be associated with DA neuron death and PD phenotypes. This review reports recent progress in the biosynthesis and pathophysiology of NM in PD.

Systematic Approach to Mimic Phenolic Natural Polymers for Biofabrication

In nature, phenolic biopolymers are utilized as functional tools and molecular crosslinkers to control the mechanical properties of biomaterials. Of particular interest are phenolic proteins/polysaccharides from living organisms, which are rich in catechol and/or gallol groups. Their strong underwater adhesion is attributed to the representative phenolic molecule, catechol, which stimulates intermolecular and intramolecular crosslinking induced by oxidative polymerization. Significant efforts have been made to understand the underlying chemistries, and researchers have developed functional biomaterials by mimicking the systems. Owing to their unique biocompatibility and ability to transform their mechanical properties, phenolic polymers have revolutionized biotechnologies. In this review, we highlight the bottom-up approaches for mimicking polyphenolic materials in nature and recent advances in related biomedical applications. We expect that this review will contribute to the rational design and synthesis of polyphenolic functional biomaterials and facilitate the production of related applications.

Rapid production of l-DOPA by Vibrio natriegens, an emerging next-generation whole-cell catalysis chassis

3, 4‐Dihydroxyphenyl‐l‐alanine (l‐DOPA) is a compound of high medical value and is considered effective as a treatment for Parkinson’s disease. Currently, bioproduction of l‐DOPA is mainly carried out by whole‐cell catalysis mediated by recombinant Escherichia coli carrying heterogeneous tyrosine phenol lyase. Vibrio natriegens is increasingly attracting attention owing to its superiority, including extremely rapid growth and high soluble protein expression capacity. In this study, we attempt to develop an efficient whole‐cell catalyst for l‐DOPA production using V. natriegens as the chassis. The maximum soluble protein expression by V. natriegens was accomplished in 4 h at 37°C, which was equivalent to that achieved by E. coli in 16 h at 16°C. Furthermore, the maximum productivity reached over 10.0 g l⁻¹ h⁻¹ in the early stage of biocatalysis, nearly two‐fold higher than previously reported. Approximately 54.0 g l⁻¹l‐DOPA was obtained with a catechol conversion rate greater than 95%. In conclusion, V. natriegens displays advantages, including rapid protein expression and catalytic rate in the catalysis process for l‐DOPA production. These findings strongly suggest that V. natriegens has remarkable potential as a whole‐cell catalysis chassis for the production of valuable chemicals.

OUP accepted manuscript

The gut microbiota is considered a key ‘metabolic organ’. Its metabolic activities play essential roles complementary to the host metabolic functions. The interplays between gut microbes and commonly used non-antibiotic drugs have garnered substantial attention over the years. Drugs can reshape the gut microorganism communities and, vice versa, the diverse gut microbes can affect drug efficacy by altering the bioavailability and bioactivity of drugs. The metabolism of drugs by gut microbial action or by microbiota–host cometabolism can transform the drugs into various metabolites. Secondary metabolites produced from the gut microbial metabolism of drugs contribute to both the therapeutic benefits and the side effects. In view of the significant effect of the gut microbiota on drug efficiency and clinical outcomes, it is pivotal to explore the interactions between drugs and gut microbiota underlying medical treatments. In this review, we describe and summarize the complex bidirectional interplays between gut microbes and drugs. We also illustrate the gut-microbiota profile altered by non-antibiotic drugs, the impacts and consequences of microbial alteration, and the biochemical mechanism of microbes impacting drug effectiveness. Understanding how the gut microbes interact with drugs and influence the therapeutic efficacy will help in discovering diverse novel avenues of regulating the gut microbes to improve the therapeutic effects and clinical outcomes of a drug in precision.

Prolyl oligopeptidase acts as a link between chaperone-mediated autophagy and macroautophagy

The accumulation of aggregated α-synuclein (α-syn) has been identified as the primary component of Lewy bodies that are the pathological hallmarks of Parkinson's disease (PD). Several preclinical studies have shown α-syn aggregation, and particularly the intermediates formed during the aggregation process to be toxic to cells. Current PD treatments only provide symptomatic relief, and α-syn serves as a promising target to develop a disease-modifying therapy for PD. Our previous studies have revealed that a small-molecular inhibitor for prolyl oligopeptidase (PREP), KYP-2047, increases α-syn degradation by accelerating macroautophagy (MA) leading to disease-modifying effects in preclinical PD models. However, α-syn is also degraded by chaperone-mediated autophagy (CMA). In the present study, we tested the effects of PREP inhibition or deletion on CMA activation and α-syn degradation. HEK-293 cells were transfected with α-syn and incubated with 1 & 10 µM KYP-2047 for 24 h. Both 1 & 10 µM KYP-2047 increased LAMP-2A levels, induced α-syn degradation and reduced the expression of Hsc70, suggesting that the PREP inhibitor prevented α-syn aggregation by activating the CMA pathway. Similarly, KYP-2047 increased the LAMP-2A immunoreactivity and reduced the Hsc70 levels in mouse primary cortical neurons. When LAMP-2A was silenced by a siRNA, KYP-2047 increased the LC3BII/LC3BI ratio and accelerated the clearance of α-syn. Additionally, KYP-2047 induced CMA effectively also when MA was blocked by bafilomycin A1. Based on our results, we suggest that PREP might function as a core network node in MA-CMA crosstalk, and PREP inhibition can reduce α-syn levels via both main autophagy systems.

Wastewater-powered high-value chemical synthesis in a hybrid bioelectrochemical system

A microbial electrochemical system could potentially be applied as a biosynthesis platform by extracting wastewater energy while converting it to value-added chemicals. However, the unfavorable thermodynamics and sluggish kinetics of in vivo whole-cell cathodic catalysis largely limit product diversity and value. Herein, we convert the in vivo cathodic reaction to in vitro enzymatic catalysis and develop a microbe-enzyme hybrid bioelectrochemical system (BES), where microbes release the electricity from wastewater (anode) to power enzymatic catalysis (cathode). Three representative examples for the synthesis of pharmaceutically relevant compounds, including halofunctionalized oleic acid based on a cascade reaction, (4-chlorophenyl)-(pyridin-2-yl)-methanol based on electrochemical cofactor regeneration, and l-3,4-dihydroxyphenylalanine based on electrochemical reduction, were demonstrated. According to the techno-economic analysis, this system could deliver high system profit, opening an avenue to a potentially viable wastewater-to-profit process while shedding scientific light on hybrid BES mechanisms toward a sustainable reuse of wastewater.

Application of bacterial tyrosinases in organic synthesis

Bacterial tyrosinases, as in the case of other bacterial oxidative enzymes, have been found to possess biochemical characteristics that typically make them more suited to applications requiring special operational conditions such as alkaline pH, high or low temperature, the presence of organic solvents, and the presence of inhibitors. Even though a great deal is known about fungal tyrosinases, bacterial tyrosinases still vastly remain underexplored for their potential application in organic synthesis. A literature survey in particular highlights the gaps in our knowledge pertaining to their biochemical properties. Bacterial tyrosinases have not only shown promise in the synthesis of medically important compounds such as L-3,4-dihydroxyphenylalanine (L-DOPA) and melanin but have also seen application in cross-linking reactions of proteins and the polymerization of environmental pollutants. Their ability to catalyse o-hydroxylation reactions have shown some degree of promise in the biocatalytic conversion of resveratrol to piceatannol, tyrosol to hydroxytyrosol, and many more. In this review, we will explore the world of bacterial tyrosinases, their current applications, and future perspectives for the application of these enzymes in organic synthesis.

Nanoparticle-Guided Brain Drug Delivery: Expanding the Therapeutic Approach to Neurodegenerative Diseases

Neurodegenerative diseases (NDs) represent a heterogeneous group of aging-related disorders featured by progressive impairment of motor and/or cognitive functions, often accompanied by psychiatric disorders. NDs are denoted as 'protein misfolding' diseases or proteinopathies, and are classified according to their known genetic mechanisms and/or the main protein involved in disease onset and progression. Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD) are included under this nosographic umbrella, sharing histopathologically salient features, including deposition of insoluble proteins, activation of glial cells, loss of neuronal cells and synaptic connectivity. To date, there are no effective cures or disease-modifying therapies for these NDs. Several compounds have not shown efficacy in clinical trials, since they generally fail to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells that greatly limits the brain internalization of endogenous substances. By engineering materials of a size usually within 1-100 nm, nanotechnology offers an alternative approach for promising and innovative therapeutic solutions in NDs. Nanoparticles can cross the BBB and release active molecules at target sites in the brain, minimizing side effects. This review focuses on the state-of-the-art of nanoengineered delivery systems for brain targeting in the treatment of AD, PD and HD.

SINEUPs: a novel toolbox for RNA therapeutics

RNA molecules have emerged as a new class of promising therapeutics to expand the range of druggable targets in the genome. In addition to ‘canonical’ protein-coding mRNAs, the emerging richness of sense and antisense long non-coding RNAs (lncRNAs) provides a new reservoir of molecular tools for RNA-based drugs. LncRNAs are composed of modular structural domains with specific activities involving the recruitment of protein cofactors or directly interacting with nucleic acids. A single therapeutic RNA transcript can then be assembled combining domains with defined secondary structures and functions, and antisense sequences specific for the RNA/DNA target of interest.

As the first representative molecules of this new pharmacology, we have identified SINEUPs, a new functional class of natural antisense lncRNAs that increase the translation of partially overlapping mRNAs. Their activity is based on the combination of two domains: an embedded mouse inverted SINEB2 element that enhances mRNA translation (effector domain) and an overlapping antisense region that provides specificity for the target sense transcript (binding domain). By genetic engineering, synthetic SINEUPs can potentially target any mRNA of interest increasing translation and therefore the endogenous level of the encoded protein.

In this review, we describe the state-of-the-art knowledge of SINEUPs and discuss recent publications showing their potential application in diseases where a physiological increase of endogenous protein expression can be therapeutic.

Tyrosinase@HKUST-1: a super stable biocatalyst efficient for catecholic product synthesis

Although metal-organic frameworks (MOFs) have been considered as promising matrices for enzyme immobilization, HKUST-1, constructed from copper acetate (CuAc2) and benzene 1,3,5-tricarboxylate (BTC), has rarely been explored for this application. In this study, mushroom tyrosinase (EC 1.14.18.1) was immobilized in the form of tyrosinase@HKUST-1 following a simple reaction procedure by mixing BTC with the enzyme prior to addition of CuAc2. The resultant biocatalyst was characterized in both structural features and catalytic properties. Upon incorporation into the HKUST-1 frameworks, the enzyme gained a prominent enhancement in stability against pH, temperature and storage: When incubated at 50 °C and pH 6.0, tyrosinase@HKUST-1 presented a half-life of 32.6 h, which is 77-fold and over tenfold higher than that of the free enzyme and its other immobilization forms, respectively; and the catalyst fully maintained its activity for at least 2 months when stored at 30 °C. The applicability of this new biocatalyst was demonstrated by employing it as catalyst for regioselective ortho-hydroxylation reactions to produce catecholic products with huge pharmacological effects, i.e., hydroxytyrosol and L-DOPA, with excellent yields and productivities. This study has thus offered a facile immobilization method to prepare a novel biocatalyst with super stability, and tyrosinase@HKUST-1 so formed from crude mushroom extract provides an efficient catalyst which can be applied to the production of catecholic products with health benefits.

Pramipexole regulates depression-like behavior via dopamine D3 receptor in a mouse model of Parkinson's disease

Depression is one of the strongest predictors of quality of life in patients with Parkinson's disease (PD). Despite the high prevalence of depression, there is no clear guidance for its treatment in PD because the evidence for the efficacy of most antidepressants remains insufficient. Pramipexole, a dopamine agonist, is one of the few drugs that has proven to be clinically useful. However, the underlying mechanisms of antidepressive effects of pramipexole are still unknown. A 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model, dopamine D2 receptor (DRD2) and D3 receptor (DRD3) knockout mice were used in our study. Compared with other dopamine D2-like receptor agonists and madopar, pramipexole improved depression-like behavior and alleviate bradykinesia in an MPTP-induced mouse model of PD. Pramipexole significantly improved depression-like behavior in DRD2^-/- mice but not in DRD3^-/- mice. These results demonstrate that the antidepressive effect of pramipexole is mediated by DRD3 but not DRD2. Our findings highlight the need to develop novel dopamine agonists specifically targeting DRD3 for the treatment of depression in PD in the future.

Oxidative Stress, Mitochondrial Dysfunction, and Neuroprotection of Polyphenols with Respect to Resveratrol in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease and is characterized by dopaminergic neuronal loss. The exact pathogenesis of PD is complex and not yet completely understood, but research has established the critical role mitochondrial dysfunction plays in the development of PD. As the main producer of cytosolic reactive oxygen species (ROS), mitochondria are particularly susceptible to oxidative stress once an imbalance between ROS generation and the organelle’s antioxidative system occurs. An overabundance of ROS in the mitochondria can lead to mitochondrial dysfunction and further vicious cycles. Once enough damage accumulates, the cell may undergo mitochondria-dependent apoptosis or necrosis, resulting in the neuronal loss of PD. Polyphenols are a group of natural compounds that have been shown to offer protection against various diseases, including PD. Among these, the plant-derived polyphenol, resveratrol, exhibits neuroprotective effects through its antioxidative capabilities and provides mitochondria protection. Resveratrol also modulates crucial genes involved in antioxidative enzymes regulation, mitochondrial dynamics, and cellular survival. Additionally, resveratrol offers neuroprotective effects by upregulating mitophagy through multiple pathways, including SIRT-1 and AMPK/ERK pathways. This compound may provide potential neuroprotective effects, and more clinical research is needed to establish the efficacy of resveratrol in clinical settings.

KDS2010, a Newly Developed Reversible MAO-B Inhibitor, as an Effective Therapeutic Candidate for Parkinson's Disease

Monoamine oxidase-B (MAO-B) is a well-established therapeutic target for Parkinson's disease (PD); however, previous clinical studies on currently available irreversible MAO-B inhibitors have yielded disappointing neuroprotective effects. Here, we tested the therapeutic potential of KDS2010, a recently synthesized potent, selective, and reversible MAO-B inhibitor in multiple animal models of PD. We designed and synthesized a series of α-aminoamide derivatives and found that derivative KDS2010 exhibited the highest potency, specificity, reversibility, and bioavailability (> 100%). In addition, KDS2010 demonstrated significant neuroprotective and anti-neuroinflammatory efficacy against nigrostriatal pathway destruction in the mouse MPTP model of parkinsonism. Treatment with KDS2010 also alleviated parkinsonian motor dysfunction in 6-hydroxydopamine-induced and A53T mutant α-synuclein overexpression rat models of PD. Moreover, KDS2010 showed virtually no toxicity or side effects in non-human primates. KDS2010 could be a next-generation therapeutic candidate for PD.

Ellagic Acid Inhibits α-Synuclein Aggregation at Multiple Stages and Reduces Its Cytotoxicity

α-Synuclein is a natively unfolded protein and its deposition in the Lewy body and Lewy neurites in the substantia nigra region of the brain is linked to Parkinson's disease (PD). The molecular mechanisms of α-synuclein aggregation and its clearance have not been well understood. Until now, several strategies have been designed to inhibit α-synuclein aggregation and related cytotoxicity. Polyphenols, small molecules, synthetic peptides, and peptide-derived molecules have been considered as potential candidates that inhibit α-synuclein oligomerization and its fibrillation, and a few of them are in clinical trials. We have identified a polyphenolic compound ellagic acid (EA) that inhibits α-synuclein aggregation. Our results demonstrated that EA inhibits primary nucleation, seeded aggregation, and membrane-induced aggregation. The cytotoxicity of α-synuclein oligomers and fibers treated with EA has been investigated and we found that EA treated oligomers and fibrils showed reduced cytotoxicity. Additionally, we also observed inhibition of membrane binding of α-synuclein by EA in SH-SY5Y cells. In conclusion, the present study suggests that small molecules such as ellagic acid have anti-amyloidogenic properties and may have therapeutic potential for Parkinson's disease and other proteinopathies.

Dopamine receptor DOP-1 engages a sleep pathway to modulate swimming in C. elegans

Animals require robust yet flexible programs to support locomotion. Here we report a pathway that connects the D1-like dopamine receptor DOP-1 with a sleep mechanism to modulate swimming in C. elegans. We show that DOP-1 plays a negative role in sustaining swimming behavior. By contrast, a pathway through the D2-like dopamine receptor DOP-3 negatively regulates the initiation of swimming, but its impact fades quickly over a few minutes. We find that DOP-1 and the GPCR kinase (G-protein-coupled receptor kinase-2) function in the sleep interneuron RIS, where DOP-1 modulates the secretion of a sleep neuropeptide FLP-11. We further show that DOP-1 and FLP-11 act in the same pathway to modulate swimming. Together, these results delineate a functional connection between a dopamine receptor and a sleep program to regulate swimming in C. elegans. The temporal transition between DOP-3 and DOP-1 pathways highlights the dynamic nature of neuromodulation for rhythmic movements that persist over time.

Chiral diene-promoted room temperature conjugate arylation: highly enantioselective synthesis of substituted chiral phenylalanine derivatives and α,α-di(arylmethyl)acetates

A highly enantiocontrolled room temperature rhodium-catalyzed conjugate arylation process was developed. The reaction proceeds through 1,4-addition of α-substituted acrylates followed by enantioselective protonation using a C1-symmetric chiral bicyclo[2,2,2] diene as the ligand and water as the proton source. This exceptionally simple protocol provides a reliable and practical access to structurally important phenylalanine derivatives and α,α-di(arylmethyl)acetates in high yields (up to 99%) with good to excellent ee values (up to 99%).

Efficient strategies to enhance plasmid stability for fermentation of recombinant Escherichia coli harboring tyrosine phenol lyase

OBJECTIVE

To solve the bottleneck of plasmid instability during microbial fermentation of L-DOPA with recombinant Escherichia coli expressing heterologous tyrosine phenol lyase.

RESULTS

The tyrosine phenol lyase from Fusobacterium nucleatum was constitutively expressed in E. coli and a fed-batch fermentation process with temperature down-shift cultivation was performed. Efficient strategies including replacing the original ampicillin resistance gene, as well as inserting cer site that is active for resolving plasmid multimers were applied. As a result, the plasmid stability was increased. The co-use of cer site on plasmid and kanamycin in culture medium resulted in proportion of plasmid containing cells maintained at 100% after fermentation for 35 h. The specific activity of tyrosine phenol lyase reached 1493 U/g dcw, while the volumetric activity increased from 2943 to 14,408 U/L for L-DOPA biosynthesis.

CONCLUSIONS

The established strategies for plasmid stability is not only promoted the applicability of the recombinant cells for L-DOPA production, but also provides important guidance for industrial fermentation with improved microbial productivity.

Early Repetitive Transcranial Magnetic Stimulation Exerts Neuroprotective Effects and Improves Motor Functions in Hemiparkinsonian Rats

Repetitive transcranial magnetic stimulation (rTMS) is a popular noninvasive technique for modulating motor cortical plasticity and has therapeutic potential for the treatment of Parkinson's disease (PD). However, the therapeutic benefits and related mechanisms of rTMS in PD are still uncertain. Accordingly, preclinical animal research is helpful for enabling translational research to explore an effective therapeutic strategy and for better understanding the underlying mechanisms. Therefore, the current study was designed to identify the therapeutic effects of rTMS on hemiparkinsonian rats. A hemiparkinsonian rat model, induced by unilateral injection of 6-hydroxydopamine (6-OHDA), was applied to evaluate the therapeutic potential of rTMS in motor functions and neuroprotective effect of dopaminergic neurons. Following early and long-term rTMS intervention with an intermittent theta burst stimulation (iTBS) paradigm (starting 24 h post-6-OHDA lesion, 1 session/day, 7 days/week, for a total of 4 weeks) in awake hemiparkinsonian rats, the effects of rTMS on the performance in detailed functional behavioral tests, including video-based gait analysis, the bar test for akinesia, apomorphine-induced rotational analysis, and tests of the degeneration level of dopaminergic neurons, were identified. We found that four weeks of rTMS intervention significantly reduced the aggravation of PD-related symptoms post-6-OHDA lesion. Immunohistochemically, the results showed that tyrosine hydroxylase- (TH-) positive neurons in the substantia nigra pars compacta (SNpc) and fibers in the striatum were significantly preserved in the rTMS treatment group. These findings suggest that early and long-term rTMS with the iTBS paradigm exerts neuroprotective effects and mitigates motor impairments in a hemiparkinsonian rat model. These results further highlight the potential therapeutic effects of rTMS and confirm that long-term rTMS treatment might have clinical relevance and usefulness as an additional treatment approach in individuals with PD.

Formation of amino acid derivatives in white and red wines during fermentation: Effects of non-Saccharomyces yeasts and Oenococcus oeni

This study aimed to investigate the effect of commercial non-Saccharomyces yeasts and Oenococcus oeni on the formation of amino acid derivatives, some of which have neuroactive properties, during fermentation in laboratory-scale processing of white and red wines. Changes in the content of amino acid derivatives during fermentation of large-scale white and red wines were also evaluated. The highest kynurenic, picolinic, and quinolinic acid concentrations were observed in white wine fermented with Torulaspora delbrueckii, Kluyveromyces thermotolerans and Saccharomyces cerevisiae simultaneously. No changes in the content of picolinic and kynurenic acid were observed during large-scale white wine fermentation. Tryptophan ethyl ester concentration in all wines increased significantly during alcoholic fermentation. Natural and O. oeni malolactic fermentation did not alter the content of picolinic acid, a neuroprotective compound, in red wine. The decrease in the content of tyramine, phenylethylamine, and dopamine in laboratory-scale white wines was observed during alcoholic fermentation.

Safety and Efficacy of Levetiracetam for the Management of Levodopa- Induced Dyskinesia in Patients with Parkinson's Disease: A Systematic Review

BACKGROUND

Levetiracetam, a novel antiepileptic drug, has shown antidyskinetic effects in experimental animal models of Parkinson's disease (PD). The tolerability and efficacy of levetiracetam in reducing the levodopa-induced dyskinesia (LID) in PD patients have not been established. Therefore, this study aims to synthesize evidence from published prospective clinical trials about the efficacy of levetiracetam for the management of LID in PD patients.

METHODS

We followed the PRISMA statement guidelines during the preparation of this systematic review. A computer literature search of PubMed, EBSCO, Scopus, MEDLINE, and the web of science was carried out. We selected prospective clinical trials assessing the anti-dyskinetic efficacy of levetiracetam for treating LID in patients with PD. The Abnormal Involuntary Movement Scale (AIMS), Clinical Global Impression Score (GCI), UPDRS III, and UPDRS IV were considered as the primary outcome measures; their data were extracted and reviewed.

RESULTS

Our review included seven clinical trials with a total of 150 patients. Of them, three studies were randomized controlled trials, and the remaining were open-label single arm trials. Four studies reported poor tolerability of the levetiracetam with mild anti-dyskinetic effects. Levetiracetam slightly improved the UPDRS-IV and AIMS scores with small effect size. In the remaining three studies, levetiracetam failed to exhibit any anti-dyskinetic effects.

CONCLUSION

Current evidence does not support the efficacy of the levetiracetam for treating LID in PD patients, however, due to the limited number of published randomized control trials (RCTs), further RCTs are required.

Ferroptosis and its potential role in the physiopathology of Parkinson's Disease

Parkinson's Disease (PD) is a common and progressive neurodegenerative disorder characterised by motor impairments as well as non-motor symptoms. While dopamine-based therapies are effective in fighting the symptoms in the early stages of the disease, a lack of neuroprotective drugs means that the disease continues to progress. Along with the traditionally recognised pathological hallmarks of dopaminergic neuronal death and intracellular α-synuclein (α-syn) depositions, iron accumulation, elevated oxidative stress and lipid peroxidation damage are further conspicuous features of PD pathophysiology. However, the underlying mechanisms linking these pathological hallmarks with neurodegeneration still remain unclear. Ferroptosis, a regulated iron dependent cell death pathway involving a lethal accumulation of lipid peroxides, shares several features with PD pathophysiology. Interestingly, α-syn has been functionally linked with the metabolism of both iron and lipid, suggesting a possible interplay between dysregulated α-syn and other PD pathological hallmarks related to ferroptosis. This review will address the importance for understanding these disease mechanisms that could be targeted therapeutically. Anti-ferroptosis molecules are neuroprotective in PD animal models and the anti-ferroptotic iron chelator, deferiprone, slowed disease progression and improved motor function in two independent clinical trials for PD. An ongoing larger multi-centre phase 2 clinical trial will confirm the therapeutic potential of deferiprone and the relevance of ferroptosis in PD. This review addresses the known pathological features of PD in relation to the ferroptosis pathway with therapeutic implications of targeting this cell death pathway.

Synthesis and characterization of L-tyrosine-conjugated quaternary ammonium salt chitosan and their cytocompatibility as a potential tissue engineering scaffold

A novel amino acid-modified biomacromolecule was designed and synthesized as the quaternary ammonium salt chitosan grafted-tyrosine (CA-g-Tyr) suitable for biomedical applications. L-tyrosine was grafted onto the quaternary ammonium salt chitosan (CA) by N-(3-dimethylaminopropy)-N-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The chemical structure of CA-g-Tyr was confirmed by Fourier transform infrared (FTIR) spectroscopy and ¹³C-NMR. The change in the crystalline structure after the graft was characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). The surface wettability and moisturizing performance of the CA-g-Tyr were also characterized. The CA-g-Tyr film possessed good hydrophilicity, and the mechanical tensile experiments showed that the introduction of tyrosine gave CA mechanical properties more suitable for blood vessel. Cell experiments showed that the endothelial cells can adhere and proliferate better on the surface of a CA-g-Tyr film than CA. The results confirm the favorable properties and biocompatibility of CA-g-Tyr with potential applications as scaffolds for tissue engineering.