Oxidative stress in the aging substantia nigra and the etiology of Parkinson's disease

Intranasal insulin treatment ameliorates spatial memory, muscular strength, and frailty deficits in 5xFAD mice

The 5xFAD mouse model shows age-related weight loss as well as cognitive and motor deficits. Metabolic dysregulation, especially impaired insulin signaling, is also present in AD. This study examined whether intranasal delivery of insulin (INI) at low (0.875 U) or high (1.750 U) doses would ameliorate these deficits compared to saline in 10-month-old female 5xFAD and B6SJL wildtype (WT) mice. INI increased forelimb grip strength in the wire hang test in 5xFAD mice in a dose-dependent manner but did not improve the performance of 5xFAD mice on the balance beam. High INI doses reduced frailty scores in 5xFAD mice and improved spatial memory in both acquisition and reversal probe trials in the Morris water maze. INI increased swim speed in 5xFAD mice but had no effect on object recognition memory or working memory in the spontaneous alternation task, nor did it improve memory in the contextual or cued fear memory tasks. High doses of insulin increased the liver, spleen, and kidney weights and reduced brown adipose tissue weights. P-Akt signaling in the hippocampus was increased by insulin in a dose-dependent manner. Altogether, INI increased strength, reduced frailty scores, and improved visual spatial memory. Hypoglycemia was not present after INI, however alterations in tissue and organ weights were present. These results are novel and important as they indicate that intra-nasal insulin can reverse cognitive, motor and frailty deficits found in this mouse model of AD.

Protopanaxadiols Eliminate Behavioral Impairments and Mitochondrial Dysfunction in Parkinson's Disease Mice Model

Currently, there are no effective therapies to cure Parkinson's disease (PD), which is the second most common neurodegenerative disease primarily characterized by motor dysfunction and degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). Protopanaxadiols (PPDs), including 20 (R)- protopanaxadiol (R-PPD) and 20 (S)- protopanaxadiol (S-PPD), are main metabolites of ginsenosides. The role of ginsenosides in neurodegenerative diseases has been thoroughly studied, however, it is unknown whether PPDs can attenuate behavioral deficits and dopaminergic neuron injury in PD model mice to date. Here, we administered PPDs to MPTP-induced PD model mice and monitored the effects on behavior and dopaminergic neurons to investigate the effects of R-PPD and S-PPD against PD. Our results showed that R-PPD and S-PPD (at a dose of 20 mg/kg, i.g.) treatment alleviated MPTP (30 mg/kg, i.p.) induced behavioral deficits. Besides, R-PPD and S-PPD protected MPP+-induced neuron injury and mitochondrial dysfunction, and reduced the abnormal expression of Cyt C, Bax, caspase-3 and Bcl-2. These findings demonstrate that R-PPD and S-PPD were potentially useful to ameliorate PD.

(+)-Borneol Protects Dopaminergic Neuronal Loss in Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-Induced Parkinson's Disease Mice: A Study of Dopamine Level using In Vivo Brain Microdialysis

Considerable research efforts have been directed toward the symptom relief of Parkinson's disease (PD) by attenuating dopamine (DA) depletion. One common feature of these existing therapies is their unavailability of preventing the neurodegenerative process of dopaminergic neurons. (+)-Borneol, a natural highly lipid-soluble bicyclic monoterpene, has been reported to regulate the levels of monoamine neurotransmitters in the central nervous system and exhibit neuroprotective effects. However, the effect of (+)-borneol on the dopaminergic neuronal loss of methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice is not defined. Herein, we first report that 30 mg/kg (+)-borneol significantly attenuated the motor deficits of PD mice, which benefits from markedly increasing the level of DA and decreasing the metabolic rate of DA in the striatum of conscious and freely moving mouse detected by ultraperformance liquid chromatography tandem mass spectrometry online combined with in vivo brain microdialysis sampling. It is worth noting that the enhanced level of DA by (+)-borneol was enabled by the reduction in loss of tyrosine hydroxylase-immunoreactive dopaminergic neurons in the substantia nigra and striatum and promotion of reserpine- or nomifensine-induced DA release in PD mice. Interestingly, (+)-borneol evidently inhibited the decreased expression levels of DA transporter (DAT) and vesicular monoamine transporter 2 (VMAT2) on the MPTP mouse model of PD. Moreover, (+)-borneol suppressed the neuroinflammation by inhibiting the production of IL-1β, IL-6, and TNF-α and attenuated oxidative stress by decreasing the level of MDA and increasing the activities of SOD and GSH-px in PD mice. These findings demonstrate that (+)-borneol protects DA neurons by inhibiting neuroinflammation and oxidative stress. Further research work for the neuroprotection mechanism of (+)-borneol will focus on reactive oxygen species-mediated apoptosis. Therefore, (+)-borneol is a potential therapeutic candidate for retarding the neurodegenerative process of PD.

Experimental Parkinson models and green chemistry approach

Parkinson's is the most common neurodegenerative disease after Alzheimer's. Motor findings in Parkinson's occur as a result of the degeneration of dopaminergic neurons starting in the substantia nigra pars compacta and ending in the putamen and caudate nucleus. Loss of neurons and the formation of inclusions called Lewy bodies in existing neurons are characteristic histopathological findings of Parkinson's. The disease primarily impairs the functional capacity of the person with cardinal findings such as tremor, bradykinesia, etc., as a result of the loss of dopaminergic neurons in the substantia nigra. Experimental animal models of Parkinson's have been used extensively in recent years to investigate the pathology of this disease. These models are generally based on systemic or local(intracerebral) administration of neurotoxins, which can replicate many features of Parkinson's mammals. The development of transgenic models in recent years has allowed us to learn more about the modeling of Parkinson's. Applying animal modeling, which shows the most human-like effects in studies, is extremely important. It has been demonstrated that oxidative stress increases in many neurodegenerative diseases such as Parkinson's and various age-related degenerative diseases in humans and that neurons are sensitive to it. In cases where oxidative stress increases and antioxidant systems are inadequate, natural molecules such as flavonoids and polyphenols can be used as a new antioxidant treatment to reduce neuronal reactive oxygen species and improve the neurodegenerative process. Therefore, in this article, we examined experimental animal modeling in Parkinson's disease and the effect of green chemistry approaches on Parkinson's disease.

Targeting NKAα1 to treat Parkinson's disease through inhibition of mitophagy-dependent ferroptosis

Dysfunction of the Na+/K+-ATPase (NKA) has been documented in various neurodegenerative diseases, yet the specific role of NKAα1 in Parkinson's disease (PD) remains incompletely understood. In this investigation, we utilized NKAα1 haploinsufficiency (NKAα1+/-) mice to probe the influence of NKAα1 on dopaminergic (DA) neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our findings reveal that NKAα1+/- mice displayed a heightened loss of DA neurons and more pronounced motor dysfunction compared to the control group when exposed to MPTP. Intriguingly, this phenomenon coincided with the activation of ferroptosis and impaired mitophagy both in vivo and in vitro. To scrutinize the role and underlying mechanism of NKAα1 in PD, we employed DR-Ab, an antibody targeting the DR-region of the NKA α subunit. Our study demonstrates that the administration of DR-Ab effectively reinstated the membrane abundance of NKAα1, thereby mitigating MPTP-induced DA neuron loss and subsequent improvement in behavioral deficit. Mechanistically, DR-Ab heightened the formation of the surface NKAα1/SLC7A11 complex, inhibiting SLC7A11-dependent ferroptosis. Moreover, DR-Ab disrupted the cytosolic interaction between NKAα1 and Parkin, facilitating the translocation of Parkin to mitochondria and enhancing the process of mitophagy. In conclusion, this study establishes NKAα1 as a key regulator of ferroptosis and mitophagy, identifying its DR-region as a promising therapeutic target for PD.

Cope with copper: From molecular mechanisms of cuproptosis to copper-related kidney diseases

Cuproptosis has recently been identified as a novel regulatory mechanism of cell death. It is characterized by the accumulation of copper in mitochondria and its binding to acylated proteins. These characteristics lead to the downregulation of iron-sulfur cluster proteins and protein toxicity stress, ultimately resulting in cell death. Cuproptosis is distinct from other types of cell death, including necrosis, apoptosis, ferroptosis, and pyroptosis. Cu induces oxidative stress damage, protein acylation, and the oligomerization of acylated TCA cycle proteins. These processes lead to the downregulation of iron-sulfur cluster proteins and protein toxicity stress, disrupting cellular Cu homeostasis, and causing cell death. Cuproptosis plays a significant role in the development and progression of various kidney diseases such as acute kidney injury, chronic kidney disease, diabetic nephropathy, kidney transplantation, and kidney stones. On the one hand, inducers of cuproptosis, such as disulfiram (DSF), chloroquinolone, and elesclomol facilitate cuproptosis by promoting cell oxidative stress. In contrast, inhibitors of Cu chelators, such as tetraethylenepentamine and tetrathiomolybdate, relieve these diseases by inhibiting apoptosis. To summarize, cuproptosis plays a significant role in the pathogenesis of kidney disease. This review comprehensively discusses the molecular mechanisms underlying cuproptosis and its significance in kidney diseases.

Oxidative stress and neurodegenerative diseases: a bidirectional Mendelian randomization study

INTRODUCTION

Oxidative stress (OS) has been linked to neurodegenerative diseases in numerous epidemiological studies; however, whether it is a pathogenesis or a downstream factor remains controversial.

METHODS

A two-sample bidirectional Mendelian randomization (MR) analysis was implemented to examine evidence of causality of 15 OS injury markers with 3 major neurodegenerative diseases using available genome-wide association studies statistics. As a main approach, inverse-variance weighted (IVW) analysis was performed. The weighted-median (WM) analysis was used to validate the relationship. In order to investigate the existence of horizontal pleiotropy and correct the IVW estimate, the Radial MR approach was applied. To gauge the consistency and robustness of the findings, several sensitivity and pleiotropy analyses were used. For this analysis, p < 0.05 indicates a nominally causal association; according to the Bonferroni correction test, p < 0.0011 indicates a statistically significant causal association.

RESULTS

Via IVW and WM, in directional MR, it was genetically predicted that zinc was nominally causally correlated with the risk of Parkinson's disease but not after Bonferroni correction test; alpha-tocopherol was nominally causally correlated with the risk of Amyotrophic lateral sclerosis (ALS) but not after Bonferroni correction test; furthermore, in reverse MR, it was genetically predicted that Alzheimer's disease was causally correlated with uric acid but not after Bonferroni correction test. These above findings were stable across sensitivity and pleiotropy analyses.

CONCLUSIONS

Based on the current study, there is no authentic genetic causal association between OS biomarkers and neurodegenerative diseases. The complex relationship is required to be confirmed in future experimental research.

Selenoprotein P in a Rodent Model of Exercise; Theorizing Its Interaction with Brain Reward Dysregulation, Addictive Behavior, and Aging

Exercise promotes health and wellness, including its operation as a protective factor against a variety of psychological, neurological, and chronic diseases. Selenium and its biomarker, selenoprotein P (SEPP1), have been implicated in health, including cancer prevention, neurological function, and dopamine signaling. SEPP1 blood serum levels were compared with a one-way ANOVA between sedentary (SED), moderately exercised (MOD) [10 m/min starting at 10 min, increasing to 60 min], and high-intensity interval training (HIIT) exercised rats [30 min in intervals of 2-min followed by a 1-min break, speed progressively increased from 10 to 21 m/min]. HIIT rats showed significantly higher serum SEPP1 concentrations compared to MOD and SED. More specifically, HIIT exercise showed an 84% increase in SEPP1 levels compared to sedentary controls. MOD rats had greater serum SEPP1 concentrations compared to SED, a 33% increase. The results indicated that increased exercise intensity increases SEPP1 levels. Exercise-induced increases in SEPP1 may indicate an adaptive response to the heightened oxidative stress. Previous studies found a significant increase in dopamine D2 receptor (D2R) binding in these same rats, suggesting a potential association between SEPP1 and dopamine signaling during exercise. Modulating antioxidants like SEPP1 through personalized therapies, including exercise, has broad implications for health, disease, and addiction.

Aspartame use and Parkinson's disease: review of associated effects on neurotransmitters, oxidative stress, and cognition

Objective: The purpose of this review was to assess the current evidence regarding the associated physiological and cognitive effects of aspartame (APM) consumption and Parkinson's Disease (PD).

METHODS

A total of 32 studies demonstrating effects of APM on monoamine deficiencies, oxidative stress, and cognitive changes were reviewed.

RESULTS

Multiple studies demonstrated decreased brain dopamine, decreased brain norepinephrine, increased oxidative stress, increased lipid peroxidation, and decreased memory function in rodents after APM use. In addition, PD animal models have been found to be more sensitive to the effects of APM.

DISCUSSION

Overall, studies of APM use over time yielded more consistent results; however, no study has examined long-term effects on APM in human PD patients. Based on the current evidence, long-term human based observational research is needed to further investigate the potential effect of APM on PD.

Physical Activity and Oxidative Stress in Aging

Biological aging, characterized by changes in metabolism and physicochemical properties of cells, has an impact on public health. Environment and lifestyle, including factors like diet and physical activity, seem to play a key role in healthy aging. Several studies have shown that regular physical activity can enhance antioxidant defense mechanisms, including the activity of enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase. However, intense or prolonged exercise can also lead to an increase in reactive oxygen species (ROS) production temporarily, resulting in oxidative stress. This phenomenon is referred to as "exercise-induced oxidative stress". The relationship between physical activity and oxidative stress in aging is complex and depends on various factors such as the type, intensity, duration, and frequency of exercise, as well as individual differences in antioxidant capacity and adaptation to exercise. In this review, we analyzed what is reported by several authors regarding the role of physical activity on oxidative stress in the aging process as well as the role of hormesis and physical exercise as tools for the prevention and treatment of sarcopenia, an aging-related disease. Finally, we reported what has recently been studied in relation to the effect of physical activity and sport on aging in women.

Polymeric Nanozyme with SOD Activity Capable of Inhibiting Self- and Metal-Induced α-Synuclein Aggregation

Despite decades of research, Parkinson's disease is still an idiopathic pathology for which no cure has yet been found. This is partly explained by the multifactorial character of most neurodegenerative syndromes, whose generation involves multiple pathogenic factors. In Parkinson's disease, two of the most important ones are the aggregation of α-synuclein and oxidative stress. In this work, we address both issues by synthesizing a multifunctional nanozyme based on grafting a pyridinophane ligand that can strongly coordinate CuII, onto biodegradable PEGylated polyester nanoparticles. The resulting nanozyme exhibits remarkable superoxide dismutase activity together with the ability to inhibit the self-induced aggregation of α-synuclein into amyloid-type fibrils. Furthermore, the combination of the chelator and the polymer produces a cooperative effect whereby the resulting nanozyme can also halve CuII-induced α-synuclein aggregation.

Oxidative Stress and Neurodegeneration: Insights and Therapeutic Strategies for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative condition marked by the gradual deterioration of dopaminergic neurons in the substantia nigra. Oxidative stress has been identified as a key player in the development of PD in recent studies. In the first part, we discuss the sources of oxidative stress in PD, including mitochondrial dysfunction, dopamine metabolism, and neuroinflammation. This paper delves into the possibility of mitigating oxidative stress as a potential treatment approach for PD. In addition, we examine the hurdles and potential of antioxidant therapy, including the challenge of delivering antioxidants to the brain and the requirement for biomarkers to track oxidative stress in PD patients. However, even if antioxidant therapy holds promise, further investigation is needed to determine its efficacy and safety in PD treatment.

The Contribution of Type 2 Diabetes to Parkinson's Disease Aetiology

Type 2 diabetes (T2D) and Parkinson's disease (PD) are chronic disorders that have a significant health impact on a global scale. Epidemiological, preclinical, and clinical research underpins the assumption that insulin resistance and chronic inflammation contribute to the overlapping aetiologies of T2D and PD. This narrative review summarises the recent evidence on the contribution of T2D to the initiation and progression of PD brain pathology. It also briefly discusses the rationale and potential of alternative pharmacological interventions for PD treatment.

Protective Effect of Resveratrol Combined with Levodopa Against Oxidative Damage in Dopaminergic Neurons

Levodopa (L-3,4-dihydroxyphenylalanine, L-Dopa) alleviates the symptoms of Parkinson's disease (PD), yet prolonged usage may give rise to severe adverse effects. Resveratrol (RSV) is a potent antioxidant, anticancer and anti-inflammatory agent. And a variety of polyphenol antioxidant compounds derived from RSV combined with levodopa have demonstrated neuroprotective activity against neuronal cell death. The purpose of this study was to examine the impact of this combination of RSV and L-Dopa on the survival rate, growth status, and reactive oxygen species (ROS) of MES23.5 dopamine (DA) neuron cells. In this study, we induced MPP+ in MES23.5 dopamine neuron cells and observed their survival rate, growth status, ROS content, as well as the effect of RSV combined with L-Dopa on cell survival. We also measured malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity levels as indicators of mitochondrial function, oxidative stress, and oxidative damage in the cells. Our results indicated that the MES23.5 dopamine neurons had decreased survival, poor growth status, and increased ROS content after MPP+ induction. Moreover, we found that MDA levels were elevated, and SOD activity levels were decreased, suggesting that the cells experienced abnormal mitochondrial function. However, when RSV was combined with L-Dopa, the cells showed a reduced level of MPP + -induced oxidative damage, with a more significant inhibitory effect observed in the RSV group at a concentration of 50 μmol/L. In conclusion, we found that the effects of co-administration of RSV with L-Dopa (100 μmol/L) was more effective than L-Dopa administered at the high dose. Thus, we found that RSV has the potential to reduce the dose of L-Dopa required to improve PD symptoms.

The Neuroprotective Flavonoids Sterubin and Fisetin Maintain Mitochondrial Health under Oxytotic/Ferroptotic Stress and Improve Bioenergetic Efficiency in HT22 Neuronal Cells

The global increase in the aging population has led to a rise in many age-related diseases with continuing unmet therapeutic needs. Research into the molecular mechanisms underlying both aging and neurodegeneration has identified promising therapeutic targets, such as the oxytosis/ferroptosis cell death pathway, in which mitochondrial dysfunction plays a critical role. This study focused on sterubin and fisetin, two flavonoids from the natural pharmacopeia previously identified as strong inhibitors of the oxytosis/ferroptosis pathway. Here, we investigated the effects of the compounds on the mitochondrial physiology in HT22 hippocampal nerve cells under oxytotic/ferroptotic stress. We show that the compounds can restore mitochondrial homeostasis at the level of redox regulation, calcium uptake, biogenesis, fusion/fission dynamics, and modulation of respiration, leading to the enhancement of bioenergetic efficiency. However, mitochondria are not required for the neuroprotective effects of sterubin and fisetin, highlighting their diverse homeostatic impacts. Sterubin and fisetin, thus, provide opportunities to expand drug development strategies for anti-oxytotic/ferroptotic agents and offer new perspectives on the intricate interplay between mitochondrial function, cellular stress, and the pathophysiology of aging and age-related neurodegenerative disorders.

Underlying Mechanisms and Treatment of Cellular Senescence-Induced Biological Barrier Interruption and Related Diseases

Given its increasing prevalence, aging is of great concern to researchers worldwide. Cellular senescence is a physiological or pathological cellular state caused by aging and a prominent risk factor for the interruption of the integrity and functionality of human biological barriers. Health barriers play an important role in maintaining microenvironmental homeostasis within the body. The senescence of barrier cells leads to barrier dysfunction and age-related diseases. Cellular senescence has been reported to be a key target for the prevention of age-related barrier diseases, including Alzheimer's disease, Parkinson's disease, age-related macular degeneration, diabetic retinopathy, and preeclampsia. Drugs such as metformin, dasatinib, quercetin, BCL-2 inhibitors, and rapamycin have been shown to intervene in cellular senescence and age-related diseases. In this review, we conclude that cellular senescence is involved in age-related biological barrier impairment. We further outline the cellular pathways and mechanisms underlying barrier impairment caused by cellular senescence and describe age-related barrier diseases associated with senescent cells. Finally, we summarize the currently used anti-senescence pharmacological interventions and discuss their therapeutic potential for preventing age-related barrier diseases.

The neurobiological effects of senescence on dopaminergic system: A comprehensive review

Over time, the body undergoes a natural, multifactorial, and ongoing process named senescence, which induces changes at the molecular, cellular, and micro-anatomical levels in many body systems. The brain, being a highly complex organ, is particularly affected by this process, potentially impairing its numerous functions. The brain relies on chemical messengers known as neurotransmitters to function properly, with dopamine being one of the most crucial. This catecholamine is responsible for a broad range of critical roles in the central nervous system, including movement, learning, cognition, motivation, emotion, reward, hormonal release, memory consolidation, visual performance, sexual drive, modulation of circadian rhythms, and brain development. In the present review, we thoroughly examine the impact of senescence on the dopaminergic system, with a primary focus on the classic delimitations of the dopaminergic nuclei from A8 to A17. We provide in-depth information about their anatomy and function, particularly addressing how senescence affects each of these nuclei.

Effects and mechanisms of bisphenols exposure on neurodegenerative diseases risk: A systemic review

Environmental bisphenols (BPs) pose a global threat to human health because of their extensive use as additives in plastic products. BP residues are increasing in various environmental media (i.e., water, soil, and indoor dust) and biological and human samples (i.e., serum and brain). Both epidemiological and animal studies have determined an association between exposure to BPs and an increased risk of neurodegenerative diseases (e.g., Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis), including cognitive abnormalities and behavioral disturbances. Hence, understanding the biological responses to different BPs is essential for prevention, and treatment. This study provides an overview of the underlying pathogenic molecular mechanisms as a valuable basis for understanding neurodegenerative disease responses to BPs, including accumulation of misfolded proteins, reduction of tyrosine hydroxylase and dopamine, abnormal hormone signaling, neuronal death, oxidative stress, calcium homeostasis, and inflammation. These findings provide new insights into the neurotoxic potential of BPs and ultimately contribute to a comprehensive health risk evaluation.

Functionalized lipid nanoparticles modulate the blood-brain barrier and eliminate α-synuclein to repair dopamine neurons

The challenge in the clinical treatment of Parkinson's disease lies in the lack of disease-modifying therapies that can halt or slow down the progression. Peptide drugs, such as exenatide (Exe), with potential disease-modifying efficacy, have difficulty in crossing the blood-brain barrier (BBB) due to their large molecular weight. Herein, we fabricate multi-functionalized lipid nanoparticles (LNP) Lpc-BoSA/CSO with BBB targeting, permeability-increasing and responsive release functions. Borneol is chemically bonded with stearic acid and, as one of the components of Lpc-BoSA/CSO, is used to increase BBB permeability. Immunofluorescence results of brain tissue of 15-month-old C57BL/6 mice show that Lpc-BoSA/CSO disperses across the BBB into brain parenchyma, and the amount is 4.21 times greater than that of conventional LNP. Motor symptoms of mice in Lpc-BoSA/CSO-Exe group are significantly improved, and the content of dopamine is 1.85 times (substantia nigra compacta) and 1.49 times (striatum) that of PD mice. α-Synuclein expression and Lewy bodies deposition are reduced to 51.85% and 44.72% of PD mice, respectively. Immunohistochemical mechanism studies show AKT expression in Lpc-BoSA/CSO-Exe is 4.23 times that of PD mice and GSK-3β expression is reduced to 18.41%. Lpc-BoSA/CSO-Exe could reduce the production of α-synuclein and Lewy bodies through AKT/GSK-3β pathway, and effectively prevent the progressive deterioration of Parkinson's disease. In summary, Lpc-BoSA/CSO-Exe increases the entry of exenatide into brain and promotes its clinical application for Parkinson's disease therapy.

Joint-tissue integrative analysis identifies high-risk genes for Parkinson's disease

The loss of dopaminergic neurons in the substantia nigra and the abnormal accumulation of synuclein proteins and neurotransmitters in Lewy bodies constitute the primary symptoms of Parkinson's disease (PD). Besides environmental factors, scholars are in the early stages of comprehending the genetic factors involved in the pathogenic mechanism of PD. Although genome-wide association studies (GWAS) have unveiled numerous genetic variants associated with PD, precisely pinpointing the causal variants remains challenging due to strong linkage disequilibrium (LD) among them. Addressing this issue, expression quantitative trait locus (eQTL) cohorts were employed in a transcriptome-wide association study (TWAS) to infer the genetic correlation between gene expression and a particular trait. Utilizing the TWAS theory alongside the enhanced Joint-Tissue Imputation (JTI) technique and Mendelian Randomization (MR) framework (MR-JTI), we identified a total of 159 PD-associated genes by amalgamating LD score, GTEx eQTL data, and GWAS summary statistic data from a substantial cohort. Subsequently, Fisher's exact test was conducted on these PD-associated genes using 5,152 differentially expressed genes sourced from 12 PD-related datasets. Ultimately, 29 highly credible PD-associated genes, including CTX1B, SCNA, and ARSA, were uncovered. Furthermore, GO and KEGG enrichment analyses indicated that these genes primarily function in tissue synthesis, regulation of neuron projection development, vesicle organization and transportation, and lysosomal impact. The potential PD-associated genes identified in this study not only offer fresh insights into the disease's pathophysiology but also suggest potential biomarkers for early disease detection.

Role of HCN channels in the functions of basal ganglia and Parkinson's disease

Parkinson's disease (PD) is a motor disorder resulting from dopaminergic neuron degeneration in the substantia nigra caused by age, genetics, and environment. The disease severely impacts a patient's quality of life and can even be life-threatening. The hyperpolarization-activated cyclic nucleotide-gated (HCN) channel is a member of the HCN1-4 gene family and is widely expressed in basal ganglia nuclei. The hyperpolarization-activated current mediated by the HCN channel has a distinct impact on neuronal excitability and rhythmic activity associated with PD pathogenesis, as it affects the firing activity, including both firing rate and firing pattern, of neurons in the basal ganglia nuclei. This review aims to comprehensively understand the characteristics of HCN channels by summarizing their regulatory role in neuronal firing activity of the basal ganglia nuclei. Furthermore, the distribution and characteristics of HCN channels in each nucleus of the basal ganglia group and their effect on PD symptoms through modulating neuronal electrical activity are discussed. Since the roles of the substantia nigra pars compacta and reticulata, as well as globus pallidus externus and internus, are distinct in the basal ganglia circuit, they are individually described. Lastly, this investigation briefly highlights that the HCN channel expressed on microglia plays a role in the pathological process of PD by affecting the neuroinflammatory response.

Implications of COVID-19 in Parkinson's disease: the purinergic system in a therapeutic-target perspective to diminish neurodegeneration

The pathophysiology of Parkinson's disease (PD) is marked by degeneration of dopaminergic neurons in the substantia nigra. With advent of COVID-19, which is closely associated with generalized inflammation and multiple organ dysfunctions, the PD patients may develop severe conditions of disease leading to exacerbated degeneration. This condition is caused by the excessive release of pro-inflammatory markers, called cytokine storm, that is capable of triggering neurodegenerative conditions by affecting the blood-brain barrier (BBB). A possible SARS-CoV-2 infection, in serious cases, may compromise the immune system by triggering a hyperstimulation of the neuroimmune response, similar to the pathological processes found in PD. From this perspective, the inflammatory scenario triggers oxidative stress and, consequently, cellular dysfunction in the nervous tissue. The P2X7R seems to be the key mediator of the neuroinflammatory process, as it acts by increasing the concentration of ATP, allowing the influx of Ca2+ and the occurrence of mutations in the α-synuclein protein, causing activation of this receptor. Thus, modulation of the purinergic system may have therapeutic potential on the effects of PD, as well as on the damage caused by inflammation of the BBB, which may be able to mitigate the neurodegeneration caused by diseases. Considering all the processes of neuroinflammation, oxidative stress, and mitochondrial dysfunction that PD propose, we can conclude that the P2X7 antagonist acts in the prevention of viral diseases, and it also controls purinergic receptors formed by multi-target compounds directed to self-amplification circuits and, therefore, may be a viable strategy to obtain the desired disease-modifying effect. Thus, purinergic system receptor modulations have a high therapeutic potential for neurodegenerative diseases such as PD.

An artificial protein modulator reprogramming neuronal protein functions

Reversible protein phosphorylation, regulated by protein phosphatases, fine-tunes target protein function and plays a vital role in biological processes. Dysregulation of this process leads to aberrant post-translational modifications (PTMs) and contributes to disease development. Despite the widespread use of artificial catalysts as enzyme mimetics, their direct modulation of proteins remains largely unexplored. To address this gap and enable the reversal of aberrant PTMs for disease therapy, we present the development of artificial protein modulators (APROMs). Through atomic-level engineering of heterogeneous catalysts with asymmetric catalytic centers, these modulators bear structural similarities to protein phosphatases and exhibit remarkable ability to destabilize the bridging μ3-hydroxide. This activation of catalytic centers enables spontaneous hydrolysis of phospho-substrates, providing precise control over PTMs. Notably, APROMs, with protein phosphatase-like characteristics, catalytically reprogram the biological function of α-synuclein by directly hydrolyzing hyperphosphorylated α-synuclein. Consequently, synaptic function is reinforced in Parkinson's disease. Our findings offer a promising avenue for reprogramming protein function through de novo PTMs strategy.

Olfactory dysfunction and its related molecular mechanisms in Parkinson's disease

Changes in olfactory function are considered to be early biomarkers of Parkinson's disease. Olfactory dysfunction is one of the earliest non-motor features of Parkinson's disease, appearing in about 90% of patients with early-stage Parkinson's disease, and can often predate the diagnosis by years. Therefore, olfactory dysfunction should be considered a reliable marker of the disease. However, the mechanisms responsible for olfactory dysfunction are currently unknown. In this article, we clearly explain the pathology and medical definition of olfactory function as a biomarker for early-stage Parkinson's disease. On the basis of the findings of clinical olfactory function tests and animal model experiments as well as neurotransmitter expression levels, we further characterize the relationship between olfactory dysfunction and neurodegenerative diseases as well as the molecular mechanisms underlying olfactory dysfunction in the pathology of early-stage Parkinson's disease. The findings highlighted in this review suggest that olfactory dysfunction is an important biomarker for preclinical-stage Parkinson's disease. Therefore, therapeutic drugs targeting non-motor symptoms such as olfactory dysfunction in the early stage of Parkinson's disease may prevent or delay dopaminergic neurodegeneration and reduce motor symptoms, highlighting the potential of identifying effective targets for treating Parkinson's disease by inhibiting the deterioration of olfactory dysfunction.

Emerging role and mechanism of HACE1 in the pathogenesis of neurodegenerative diseases: A promising target

HACE1 is a member of the HECT domain-containing E3 ligases with 909 amino acid residues, containing N-terminal ankyrin-repeats (ANK) and C-terminal HECT domain. Previously, it was shown that HACE1 is inactive in human tumors and plays a crucial role in the initiation, progression, and invasion of malignant tumors. Recent studies indicated that HACE1 might be closely involved in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. HACE1 interacts with its substrates, including Ras-related C3 botulinum toxin substrate 1 (Rac1), nuclear factor erythroid 2-related factor 2 (Nrf2), tumor necrosis factor receptor (TNFR), and optineurin (OPTN), through which participates in several pathophysiological processes, such as oxidative stress, autophagy and inflammation. Therefore, in this review, we elaborately describe the essential substrates of HACE1 and illuminate the pathophysiological processes by which HACE1 is involved in neurodegenerative diseases. We provide a new molecular target for neurodegenerative diseases.

Circadian regulation of microglia function: Potential targets for treatment of Parkinson's Disease

Circadian rhythms are involved in the regulation of many aspects of the body, including cell function, physical activity and disease. Circadian disturbance often predates the typical symptoms of neurodegenerative diseases and is not only a non-motor symptom, but also one of the causes of their occurrence and progression. Glial cells possess circadian clocks that regulate their function to maintain brain development and homeostasis. Emerging evidence suggests that the microglial circadian clock is involved in the regulation of many physiological processes, such as cytokine release, phagocytosis, and nutritional and metabolic support, and that disruption of the microglia clock may affect multiple aspects of Parkinson's disease, especially neuroinflammation and α-synuclein processes. Herein, we review recent advances in the circadian control of microglia function in health and disease, and discuss novel pharmacological interventions for microglial clocks in neurodegenerative disorders.

J24335 exerts neuroprotective effects against 6-hydroxydopamine-induced lesions in PC12 cells and mice

Parkinson's disease is the second most prevalent age-related neurodegenerative disease and disrupts the lives of people aged >60 years. Meanwhile, single-target drugs becoming inapplicable as PD pathogenesis diversifies. Mitochondrial dysfunction and neurotoxicity have been shown to be relevant to the pathogenesis of PD. The novel synthetic compound J24335 (11-Hydroxy-1-(8-methoxy-5-(trifluoromethyl)quinolin-2-yl)undecan-1-one oxime), which has been researched similarly to J2326, has the potential to be a multi-targeted drug and alleviate these lesions. Therefore, we investigated the mechanism of action and potential neuroprotective function of J24335 against 6-OHDA-induced neurotoxicity in mice, and in PC12 cell models. The key target of action of J24335 was also screened. MTT assay, LDH assay, flow cytometry, RT-PCR, LC-MS, OCR and ECAR detection, and Western Blot analysis were performed to characterize the neuroprotective effects of J24335 on PC12 cells and its potential mechanism. Behavioral tests and immunohistochemistry were used to evaluate behavioral changes and brain lesions in mice. Moreover, bioinformatics was employed to assess the drug-likeness of J24335 and screen its potential targets. J24335 attenuated the degradation of mitochondrial membrane potential and enhanced glucose metabolism and mitochondrial biosynthesis to ameliorate 6-OHDA-induced mitochondrial dysfunction. Animal behavioral tests demonstrated that J24335 markedly improved motor function and loss of TH-positive neurons and dopaminergic nerve fibers, and contributed to an increase in the levels of dopamine and its metabolites in brain tissue. The activation of both the CREB/PGC-1α/NRF-1/TFAM and PKA/Akt/GSK-3β pathways was a major contributor to the neuroprotective effects of J24335. Furthermore, bioinformatics predictions revealed that J24335 is a low toxicity and highly BBB permeable compound targeting 8 key genes (SRC, EGFR, ERBB2, SYK, MAPK14, LYN, NTRK1 and PTPN1). Molecular docking suggested a strong and stable binding between J24335 and the 8 core targets. Taken together, our results indicated that J24335, as a multi-targeted neuroprotective agent with promising therapeutic potential for PD, could protect against 6-OHDA-induced neurotoxicity via two potential pathways in mice and PC12 cells.

Oxidation of dopamine and related catechols in dopaminergic brain regions in Parkinson's disease and during ageing in non-Parkinsonian subjects

The present study was performed to examine if catechol oxidation is higher in brains from patients with Parkinson's disease compared to age-matched controls, and if catechol oxidation increases with age. Brain tissue from Parkinson patients and age-matched controls was examined for oxidation of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylalanine (DOPA) to corresponding quinones, by measurement of 5-S-cysteinyl-dopamine, 5-S-cysteinyl-DOPAC and 5-S-cysteinyl-DOPA. The cysteinyl catechols are assumed to be biomarkers for DA, DOPAC and DOPA autoxidation and part of the biosynthetic pathway of neuromelanin. The concentrations of the 5-S-cysteinyl catechols were lower, whereas the 5-S-cysteinyl-DA/DA and 5-S-cysteinyl-DOPAC/DOPAC ratios tended to be higher in the Parkinson group compared to controls, which was interpreted as a higher degree of oxidation. High 5-S-cysteinyl-DA/DA ratios were found in the substantia nigra of a sub-population of the Parkinson group. Based on 5-S-cysteinyl-DA/DA ratios, dopamine oxidation was found to increase statistically significantly with age in the caudate nucleus, and non-significantly in the substantia nigra. In conclusion, the occurrence of 5-S-cysteinyl-DA, 5-S-cysteinyl-DOPAC and 5-S-cysteinyl-DOPA was demonstrated in dopaminergic brain areas of humans, a tendency for higher oxidation of DA in the Parkinson group compared to controls was observed as well as a statistically significant increase in DA oxidation with age. Possibly, autoxidation of DA and other catechols are involved in both normal and pathological ageing of the brain. This study confirms one earlier but small study, as well as complements one study on non-PD cases and one study on both PD cases and controls on NM bound or integrated markers or catechols.

New Insights into Oxidative Stress and Inflammatory Response in Neurodegenerative Diseases

Oxidative stress (OS) and inflammation are two important and well-studied pathological hallmarks of neurodegenerative diseases (NDDs). Due to elevated oxygen consumption, the high presence of easily oxidizable polyunsaturated fatty acids and the weak antioxidant defenses, the brain is particularly vulnerable to oxidative injury. Uncertainty exists over whether these deficits contribute to the development of NDDs or are solely a consequence of neuronal degeneration. Furthermore, these two pathological hallmarks are linked, and it is known that OS can affect the inflammatory response. In this review, we will overview the last findings about these two pathways in the principal NDDs. Moreover, we will focus more in depth on amyotrophic lateral sclerosis (ALS) to understand how anti-inflammatory and antioxidants drugs have been used for the treatment of this still incurable motor neuron (MN) disease. Finally, we will analyze the principal past and actual clinical trials and the future perspectives in the study of these two pathological mechanisms.

Mito-metformin protects against mitochondrial dysfunction and dopaminergic neuronal degeneration by activating upstream PKD1 signaling in cell culture and MitoPark animal models of Parkinson's disease

Impaired mitochondrial function and biogenesis have strongly been implicated in the pathogenesis of Parkinson's disease (PD). Thus, identifying the key signaling mechanisms regulating mitochondrial biogenesis is crucial to developing new treatment strategies for PD. We previously reported that protein kinase D1 (PKD1) activation protects against neuronal cell death in PD models by regulating mitochondrial biogenesis. To further harness the translational drug discovery potential of targeting PKD1-mediated neuroprotective signaling, we synthesized mito-metformin (Mito-Met), a mitochondria-targeted analog derived from conjugating the anti-diabetic drug metformin with a triphenylphosphonium functional group, and then evaluated the preclinical efficacy of Mito-Met in cell culture and MitoPark animal models of PD. Mito-Met (100-300 nM) significantly activated PKD1 phosphorylation, as well as downstream Akt and AMPKα phosphorylation, more potently than metformin, in N27 dopaminergic neuronal cells. Furthermore, treatment with Mito-Met upregulated the mRNA and protein expression of mitochondrial transcription factor A (TFAM) implying that Mito-Met can promote mitochondrial biogenesis. Interestingly, Mito-Met significantly increased mitochondrial bioenergetics capacity in N27 dopaminergic cells. Mito-Met also reduced mitochondrial fragmentation induced by the Parkinsonian neurotoxicant MPP+ in N27 cells and protected against MPP+-induced TH-positive neurite loss in primary neurons. More importantly, Mito-Met treatment (10 mg/kg, oral gavage for 8 week) significantly improved motor deficits and reduced striatal dopamine depletion in MitoPark mice. Taken together, our results demonstrate that Mito-Met possesses profound neuroprotective effects in both in vitro and in vivo models of PD, suggesting that pharmacological activation of PKD1 signaling could be a novel neuroprotective translational strategy in PD and other related neurocognitive diseases.

Microbial dysbiosis and the aging process: a review on the potential age-deceleration role of Lactiplantibacillus plantarum

Gut microbiota dysbiosis has been a serious risk factor for several gastric and systemic diseases. Recently, gut microbiota's role in aging was discussed. Available preclinical evidence suggests that the probiotic bacteria Lactiplantibacillus plantarums (LP) may influence the aging process via modulation of the gut microbiota. The present review summarized compelling evidence of LP's potential effect on aging hallmarks such as oxidative stress, inflammation, DNA methylation, and mitochondrial dysfunction. LP gavage modulates gut microbiota and improves overall endurance in aging animal models. LP cell constituents exert considerable antioxidant potential which may reduce ROS levels directly. In addition, restored gut microbiota facilitate a healthy intestinal milieu and accelerate multi-channel communication via signaling factors such as SCFA and GABA. Signaling factors further activate specific transcription factor Nrf2 in order to reduce oxidative damage. Nrf2 regulates cellular defense systems involving anti-inflammatory cytokines, MMPs, and protective enzymes against MAPKs. We concluded that LP supplementation may be an effective approach to managing aging and associated health risks.

Crocin attenuates the lipopolysaccharide-induced neuroinflammation via expression of AIM2 and NLRP1 inflammasome in an experimental model of Parkinson's disease

The underlying mechanisms of inflammasome activation and the following dopaminergic neuron loss caused by chronic neuroinflammation remain entirely unclear. Therefore, this study aimed to investigate the impact of crocin on the inflammasome complex within an experimental model of Parkinson's disease (PD) using male Wistar rats. PD was induced by the stereotaxic injection of lipopolysaccharide (LPS), and crocin was intraperitoneally administrated one week before the lesion, and then treatment continued for 21 days. Open field (OF) and elevated plus maze tests were applied for behavioral assays. Furthermore, hematoxylin and eosin (H&E) and immunostaining were performed on whole brain tissue, while dissected substantia nigra (SN) was used for immunoblotting and real-time PCR to evaluate compartments involved in PD. The time spent in the center of test was diminished in the LPS group, while treatment with 30 mg/kg of crocin significantly increased it. H&E staining showed a significant increase in cell infiltration at the site of LPS injection, which was ameliorated upon crocin treatment. Notably, crocin-treated animals showed a reduced number of caspase-1 and IL-1β positive cells, whereas the number of positive cells was increased in the LPS group (P < 0.05). A significant decrease in tyrosine hydroxylase (TH) expression was also found in the LPS group, while crocin treatment significantly elevated its expression. IL-1β, IL-18, NLRP1, and AIM2 genes expression significantly increased in the LPS group. On the other hand, treatment with 30 mg/kg of crocin significantly downregulated the expression levels of these genes along with NLRP1 (P < 0.05). In summary, our findings suggest that crocin reduces neuroinflammation in PD by diminishing IL-1β and caspase-1 levels, potentially by inhibiting the expression of AIM2 and NLRP1 genes.

Parkinson's Disease: Cells Succumbing to Lifelong Dopamine-Related Oxidative Stress and Other Bioenergetic Challenges

The core pathological event in Parkinson's disease (PD) is the specific dying of dopamine (DA) neurons of the substantia nigra pars compacta (SNc). The reasons why SNc DA neurons are especially vulnerable and why idiopathic PD has only been found in humans are still puzzling. The two main underlying factors of SNc DA neuron vulnerability appear related to high DA production, namely (i) the toxic effects of cytoplasmic DA metabolism and (ii) continuous cytosolic Ca2+ oscillations in the absence of the Ca2+-buffer protein calbindin. Both factors cause oxidative stress by producing highly reactive quinones and increasing intra-mitochondrial Ca2+ concentrations, respectively. High DA expression in human SNc DA neuron cell bodies is suggested by the abundant presence of the DA-derived pigment neuromelanin, which is not found in such abundance in other species and has been associated with toxicity at higher levels. The oxidative stress created by their DA production system, despite the fact that the SN does not use unusually high amounts of energy, explains why SNc DA neurons are sensitive to various genetic and environmental factors that create mitochondrial damage and thereby promote PD. Aging increases multiple risk factors for PD, and, to a large extent, PD is accelerated aging. To prevent PD neurodegeneration, possible approaches that are discussed here are (1) reducing cytoplasmic DA accumulation, (2) blocking cytoplasmic Ca2+ oscillations, and (3) providing bioenergetic support.

Adipokines, Vitamin D, and Selected Inflammatory Biomarkers among Parkinson's Disease Patients with and without Dyskinesia: A Preliminary Examination

Parkinson's disease (PD), a widely recognized neurodegenerative disorder, is characterized by a spectrum of symptoms including motor fluctuations and dyskinesia. Neuroinflammation and dysregulation of adipokines are increasingly implicated in the progression of PD. This preliminary study investigated the levels of inflammatory biomarkers and adipokines, namely interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), C-reactive protein (CRP), visfatin, progranulin, and 25(OH)-vitamin D in 52 PD patients, divided equally between those with and without dyskinesia and 26 healthy controls. Significant differences in the levels of IL-6, TNF-α, visfatin, and progranulin were noted between the groups. Patients with dyskinesia exhibited notably higher IL-6 levels compared to controls, and TNF-α was significantly elevated in both PD patient groups relative to the control group. Additionally, visfatin levels were higher in PD patients without dyskinesia as opposed to those with dyskinesia, and progranulin levels were elevated in the non-dyskinetic PD group compared to controls. The findings highlight the potential role of the examined biomarkers in the pathophysiology of PD. Changes in levels of the tested inflammatory biomarkers and adipokines might be associated with Parkinson's disease and its symptoms such as dyskinesia.

Developing Peripheral Biochemical Biomarkers of Brain Disorders: Insights from Zebrafish Models

High prevalence of human brain disorders necessitates development of the reliable peripheral biomarkers as diagnostic and disease-monitoring tools. In addition to clinical studies, animal models markedly advance studying of non-brain abnormalities associated with brain pathogenesis. The zebrafish (Danio rerio) is becoming increasingly popular as an animal model organism in translational neuroscience. These fish share some practical advantages over mammalian models together with high genetic homology and evolutionarily conserved biochemical and neurobehavioral phenotypes, thus enabling large-scale modeling of human brain diseases. Here, we review mounting evidence on peripheral biomarkers of brain disorders in zebrafish models, focusing on altered biochemistry (lipids, carbohydrates, proteins, and other non-signal molecules, as well as metabolic reactions and activity of enzymes). Collectively, these data strongly support the utility of zebrafish (from a systems biology standpoint) to study peripheral manifestations of brain disorders, as well as highlight potential applications of biochemical biomarkers in zebrafish models to biomarker-based drug discovery and development.

The study of the protective effect of mitochondrial uncouplers during acute toxicity of the fungicide difenoconazole in different organs of mice

Pesticides represent a serious problem for agricultural workers due to their neurotoxic effects. The aim of this study was to evaluate the ability of pharmacological oxidative phosphorylation uncouplers to reduce the effect of the difenoconazole fungicide on mitochondrial DNA (mtDNA) of various organs in mice. Injections of difenoconazole caused cognitive deficits in mice, and the protonophore 2,4-dinitrophenol (2,4-DNP) and Azur I (AzI), a demethylated metabolite of methylene blue (MB), prevented the deterioration of cognitive abilities in mice induced by difenoconazole. Difenoconazole increased the rate of reactive oxygen species (ROS) production, likely through inhibition of complex I of the mitochondrial respiratory chain. After intraperitoneal administration of difenoconazole lungs, testes and midbrain were most sensitive to the accumulation of mtDNA damage. In contrast, the cerebral cortex and hippocampus were not tolerant to the effects of difenoconazole. The protonophore 2,4-DNP reduced the rate of ROS formation and significantly reduced the amount of mtDNA damage caused by difenoconazole in the midbrain, and partially, in the lungs and testes. MB, an alternative electron carrier capable of bypassing inhibited complex I, had no effect on the effect of difenoconazole on mtDNA, while its metabolite AzI, a demethylated metabolite of MB, was able to protect the mtDNA of the midbrain and testes. Thus, mitochondria-targeted therapy is a promising approach to reduce pesticide toxicity for agricultural workers.

Are high copper levels related to Alzheimer's and Parkinson's diseases? A systematic review and meta-analysis of articles published between 2011 and 2022

Copper performs an important role in the brain, but in high levels it can be neurotoxic. Further, some authors have described that copper dyshomeostasis could be related with neurodegenerative diseases. Thus, this review was performed to observe whether high copper levels are related to Alzheimer's and Parkinson's diseases (AD and PD), using the literature published recently. Articles that measured copper levels in AD or PD patients was included, as well as they that measured copper levels in models used to mimic these diseases. Also, results about high copper levels effects and its relationship with AD and PD observed in laboratory animals are considered. In summary, 38 and 24 articles with AD and PD patients were included, respectively. Despite of the heterogeneity between the studies in humans, meta-analysis has demonstrated that there is an increase in free and total copper levels in the blood of AD patients compared to controls, and a decrease in copper levels in PD patients. A decrease in the metal content in postmortem brain tissue was observed in AD and PD. In manuscripts using animal models that mimic AD and PD, it was included seven and three articles, respectively. Two of them have reported an increase in copper concentrations in AD model, and one in PD model. Finally, studies with laboratory animals have concluded that high copper levels are related to oxidative stress, neuroinflammation, mitochondrial dysfunction, changes in neurotransmitter levels, cell death, and reduced both cognitive and locomotor activity, which are also described in AD or PD.

The Hypoxia Response Pathway: A Potential Intervention Target in Parkinson's Disease?

Parkinson's disease (PD) is a progressive neurodegenerative disorder for which only symptomatic treatments are available. Both preclinical and clinical studies suggest that moderate hypoxia induces evolutionarily conserved adaptive mechanisms that enhance neuronal viability and survival. Therefore, targeting the hypoxia response pathway might provide neuroprotection by ameliorating the deleterious effects of mitochondrial dysfunction and oxidative stress, which underlie neurodegeneration in PD. Here, we review experimental studies regarding the link between PD pathophysiology and neurophysiological adaptations to hypoxia. We highlight the mechanistic differences between the rescuing effects of chronic hypoxia in neurodegeneration and short-term moderate hypoxia to improve neuronal resilience, termed "hypoxic conditioning". Moreover, we interpret these preclinical observations regarding the pharmacological targeting of the hypoxia response pathway. Finally, we discuss controversies with respect to the differential effects of hypoxia response pathway activation across the PD spectrum, as well as intervention dosing in hypoxic conditioning and potential harmful effects of such interventions. We recommend that initial clinical studies in PD should focus on the safety, physiological responses, and mechanisms of hypoxic conditioning, as well as on repurposing of existing pharmacological compounds. © 2023 International Parkinson and Movement Disorder Society.

Can pluripotent/multipotent stem cells reverse Parkinson's disease progression?

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by continuous and selective degeneration or death of dopamine neurons in the midbrain, leading to dysfunction of the nigrostriatal neural circuits. Current clinical treatments for PD include drug treatment and surgery, which provide short-term relief of symptoms but are associated with many side effects and cannot reverse the progression of PD. Pluripotent/multipotent stem cells possess a self-renewal capacity and the potential to differentiate into dopaminergic neurons. Transplantation of pluripotent/multipotent stem cells or dopaminergic neurons derived from these cells is a promising strategy for the complete repair of damaged neural circuits in PD. This article reviews and summarizes the current preclinical/clinical treatments for PD, their efficacies, and the advantages/disadvantages of various stem cells, including pluripotent and multipotent stem cells, to provide a detailed overview of how these cells can be applied in the treatment of PD, as well as the challenges and bottlenecks that need to be overcome in future translational studies.

Efficacy and mechanism study of Baichanting compound, a combination of Acanthopanax senticosus (Rupr. and Maxim.) Harms, Paeonia lactiflora Pall and Uncaria rhynchophylla (Miq.) Miq. ex Havil, on Parkinson's disease based on metagenomics and metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a rapidly progressing neurological disorder. Currently, Medication for PD has numerous limitations. Baichanting Compound (BCT) is a Chinese herbal prescription, a Combination of Acanthopanax senticosus (Rupr. and Maxim.) Harms, Paeonia lactiflora Pall and Uncaria rhynchophylla (Miq.) Miq. ex Havil, that was developed to treat PD and holds a national patent (ZL, 201110260536.3).

AIM OF THE STUDY

To clarify the therapeutic effect of BCT on PD and explore its possible mechanism based on metabolomics and metagenomics.

MATERIALS AND METHODS

C57BL/6 mice were used as a control group, and α-syn transgenic C57BL/6 mice were randomly assigned to the PD (without treatment) or BCT (with BCT treatment) group. UPLC-MS was performed to detect dopamine levels in brain tissue, while ELISA was used to determine inflammatory factors such as IL-1β, IL-6, TNF-α, IFN-γ and NO, and oxidative stress indicators such as malondialdehyde, superoxide dismutase and glutathione peroxidase enzyme activity. Fecal metabolomics was used to detect fecal metabolic profiles, screen differential metabolic markers, and predict metabolic pathways by KEGG enrichment analysis. Metagenomics was used to determine the intestinal microbial composition, and KO enrichment analysis was performed to predict the potential function of different gut microbiota. Finally, Spearman correlation analysis was used to find the possible relationships among intestinal flora, metabolic markers, inflammatory factors, oxidative stress and dopamine levels.

RESULTS

BCT increased the superoxide dismutase activity of α-Syn transgenic C57BL/6 mice (P < 0.01), decreased the levels of TNF-α, IFN-γ, IL-1β, IL-6, NO and malondialdehyde (P < 0.01, 0.05), and increased the release of dopamine (P < 0.01). Metabolomics results show that BCT could regulate Acetatifactor, Marvinbryantia, Faecalitalea, Anaeromassilibacillus, Anaerobium, Pseudobutyrivibrio and Lachnotalea and Acetatifactor_muris, Marvinbryantia_formatexigens, Lachnotalea_sp_AF33_28, Faecalitalea_sp_Marseille_P3755 and Anaerobium_acetethylicum, Gemmiger_sp_An120 abundance to restore intestinal flora function, and reverse fecal metabolism trend, restoring the content of α-D-glucose, cytidine, L-glutamate, L-glutamine, N-acetyl-L-glutamate, raffinose and uracil. In addition, it regulates arginine biosynthesis, D-glutamine and D-glutamate, pyrimidine, galactose and alanine, aspartate and glutamate metabolic pathways.

CONCLUSION

BCT may regulate the composition of the gut microbiota to reverse fecal metabolism in PD mice to protect the substantia nigra and striatum from oxidative stress and inflammatory factors and ultimately play an anti-PD role.

Fine-tuning the circadian system with light treatment for Parkinson's disease: an in-depth, critical review

Late in the twentieth century, interest intensified regarding the involvement of the circadian system in the aetiology and treatment of Parkinson's disease (PD). It has been envisaged that this approach might provide relief beyond the limited benefits and severe side effects achieved by dopamine (DA) replacement. In the first clinical article, published in 1996, polychromatic light was used to shift the circadian clock as it is considered to be the most powerful zeitgeber (time keeper) that can be implemented to realign circadian phase. Since that time, 11 additional articles have implemented light treatment (LT) in various forms as an adjuvant to DA replacement. In spite of the growing interest in this area, the systematic exploration of LT in PD has been stymied by several methodological factors. Such factors include time of LT presentation, duration of studies undertaken, frequency of light employed, dose of light prescribed and relevance of experimental design to the prolonged course of the illness. On this basis, it is the purpose of this review to provide an in-depth examination of these papers, and the underlying preclinical work, to provide critique, thereby giving direction for future studies in therapeutic applications of LT for PD. Consideration of this collective work may serve to carve a path for future research and thereby improve the lives of those suffering from this debilitating disorder.

Optimization of Pramipexole-Loaded In Situ Thermosensitive Intranasal Gel for Parkinson's Disease

The objective of the present work was to develop and optimize an intranasal in situ gel of Pramipexole dihydrochloride for enhanced drug delivery, better patient acceptability, and possible proper treatment of Parkinson's disease. Preliminary studies were performed to select formulation components and identify key variables affecting the formulation. The optimization of the in situ gelling system of Pramipexole dihydrochloride was achieved by applying 32 full factorial design using Design-Expert® software (Stat-Ease 9.0.6 version) and taking concentrations of Poloxamer 407 (X1) and HPMC K4M (X2) as independent variables. The gelling temperature, gel strength, and percentage of drug diffused after 8 h were taken as dependent variables. The software provided an optimized formulation, with 16.50% of X1 and 0.2% of X2 with the highest desirability. An in vivo drug retention time study was performed for the optimized formulation in Wistar rats. The results of the optimization process demonstrated that the selected gel formulation exhibited desirable characteristics, including gelation near body temperature, good gel strength, suitable viscosity, and sustained drug release. The optimized formulation displayed significantly higher drug retention, lasting about 5 h, versus the plain poloxamer gel formulation. Hence, it was concluded that the optimized formulation will remain affixed at the site of application for a significant time after intranasal administration and consequently sustain the release of the drug. The optimized formulation was found to be stable during the stability studies. The developed dosage form may improve patient compliance, enhance nasal drug residence, and offer sustained drug release. However, further clinical studies are necessary to validate these findings.

Ergothioneine Prevents Neuronal Cell Death Caused by the Neurotoxin 6-Hydroxydopamine

Neuronal cell death is a key mechanism involved in the development and exacerbation of Parkinson's disease (PD). The excessive production of reactive oxygen species (ROS) is a major cause leading to neuronal death; therefore, compounds that prevent oxidative stress-dependent neuronal death may be promising as a preventive method for PD. Ergothioneine is a natural amino acid with antioxidant properties, and its protective functions in the body are attracting attention. However, there has been no investigation into the protective functions of ergothioneine using in vivo and in vitro PD models. Thus, in this study, we analyzed the efficacy of ergothioneine against 6-hydroxydopamine (6-OHDA)-dependent neuronal cell death using immortalized hypothalamic neurons (GT1-7 cells). First, we found that ergothioneine prevents 6-OHDA-dependent neuronal cell death by suppressing ROS overproduction in GT1-7 cells. The cytoprotective effect of ergothioneine was partially abolished by verapamil, an inhibitor of OCTN1, which is involved in ergothioneine uptake. Furthermore, ergothioneine-rich Rice-koji (Ergo-koji) showed cytoprotective and antioxidant effects similar to those of ergothioneine. Taken together, these results suggest that ergothioneine or foods containing ergothioneine may be an effective method for preventing the development and progression of PD.

Effect of the Flavonoid Rutin on the Modulation of the Myenteric Plexuses in an Experimental Model of Parkinson's Disease

Recent discoveries have shown that enteric glial cells play an important role in different neurodegenerative disorders, such as Parkinson's disease (PD), which is characterized by motor dysfunctions caused by the progressive loss of dopaminergic neurons in the substance nigra pars compacta and non-motor symptoms including gastrointestinal dysfunction. In this study, we investigated the modulatory effects of the flavonoid rutin on the behavior and myenteric plexuses in a PD animal model and the response of enteric glia. Adult male Wistar rats were submitted to stereotaxic injection with 6-hydroxydopamine or saline, and they were untreated or treated with rutin (10 mg/kg) for 14 days. The ileum was collected to analyze tissue reactivity and immunohistochemistry for neurons (HuC/HuD) and enteric glial cells (S100β) in the myenteric plexuses. Behavioral tests demonstrated that treatment with rutin improved the motor capacity of parkinsonian animals and improved intestinal transit without interfering with the cell population; rutin treatment modulated the reactivity of the ileal musculature through muscarinic activation, reducing relaxation through the signaling pathway of nitric oxide donors, and increased the longitudinal contractility of the colon musculature in parkinsonian animals. Rutin revealed modulatory activities on the myenteric plexus, bringing relevant answers regarding the effect of the flavonoid in this system and the potential application of PD adjuvant treatment.

The Absence of Gastrointestinal Redox Dyshomeostasis in the Brain-First Rat Model of Parkinson's Disease Induced by Bilateral Intrastriatal 6-Hydroxydopamine

The gut-brain axis plays an important role in Parkinson's disease (PD) by acting as a route for vagal propagation of aggregated α-synuclein in the gut-first endophenotype and as a mediator of gastrointestinal dyshomeostasis via the nigro-vagal pathway in the brain-first endophenotype of the disease. One important mechanism by which the gut-brain axis may promote PD is by regulating gastrointestinal redox homeostasis as overwhelming evidence suggests that oxidative stress plays a key role in the etiopathogenesis and progression of PD and the gastrointestinal tract maintains redox homeostasis of the organism by acting as a critical barrier to environmental and microbiological electrophilic challenges. The present aim was to utilize the bilateral intrastriatal 6-hydroxydopamine (6-OHDA) brain-first PD model to study the effects of isolated central pathology on redox homeostasis of the gastrointestinal tract. Three-month-old male Wistar rats were either not treated (intact controls; CTR) or treated bilaterally intrastriatally with vehicle (CIS) or 6-OHDA (6-OHDA). Motor deficits were assessed with the rotarod performance test, and the duodenum, ileum, and colon were dissected for biochemical analyses 12 weeks after the treatment. Lipid peroxidation, total antioxidant capacity, low-molecular-weight thiols, and protein sulfhydryls, the activity of total and Mn/Fe superoxide dismutases, and total and azide-insensitive catalase/peroxidase were measured. Both univariate and multivariate models analyzing redox biomarkers indicate that significant disturbances in gastrointestinal redox balance are not present. The findings demonstrate that motor impairment observed in the brain-first 6-OHDA model of PD can occur without concurrent redox imbalances in the gastrointestinal system.

Geniposide protects against neurotoxicity in mouse models of rotenone-induced Parkinson's disease involving the mTOR and Nrf2 pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Gardeniae, with the effects of discharging fire, eliminating vexation, reducing fever and causing diuresis, and cooling blood to remove apthogentic heat, could be used to treat Parkinson's disease (PD). Geniposide, as the main active ingredient of Fructus Gardeniae, has been shown to have neuroprotective effects in several rodent models. Rotenone, a commonly used neurotoxin, induced PD model progresses slowly, but simulates the pathological changes of PD's slow progression.

AIM OF THE STUDY

Herein, we mainly investigated the neuroprotective effects of geniposide on rotenone-induced mouse model of PD and the underlined mechanism.

MATERIALS AND METHODS

C57BL/6 mice were treated with rotenone (30 mg/kg, p. o.) daily for 60 days. Geniposide (25 and 50 mg/kg, p. o.) were administered at alterative day 30 min before rotenone. On day 60, the challenging beam, spontaneous activity, and adhesive removal tests were performed to evaluate the motor activity. Dopamine, DOPAC and HVA levels were detected by UPLC-MS/MS methods. Dopaminergic neurodegeneration was assessed using immunohistochemistry staining. ROS production, MDA level and GSH: GSSG ratio were measured to analyze oxidative stress. Cleavage of PARP and caspase-3 were detected to assess neuronal apoptosis. The expression of Nrf2 and mTOR signaling were detected using Western blot.

RESULTS

Geniposide improved motor dysfunction, restored neurotransmitters levels, and attenuated dopaminergic neurodegeneration induced by rotenone in mice. Geniposide suppressed rotenone-induced neuronal oxidative damage associated with Nrf2 signaling, and neuronal apoptosis involving mTOR pathway.

CONCLUSIONS

Geniposide may exert a neuroprotective effect in a mouse model of PD by rotenone, and this effect might be relevant to Nrf2 associated antioxidant signaling and mTOR involved anti-apoptosis pathway.

Aureusidin ameliorates 6-OHDA-induced neurotoxicity via activating Nrf2/HO-1 signaling pathway and preventing mitochondria-dependent apoptosis pathway in SH-SY5Y cells and Caenorhabditis elegans

Movement disorder Parkinson's disease (PD) is the second most common neurodegenerative disease in the world after Alzheimer's disease, which severely affects the quality of patients' lives and imposes an increasingly heavy socioeconomic burden. Aureusidin is a kind of natural flavonoid compound with anti-inflammatory and anti-oxidant activities, while its pharmacological action and mechanism are rarely reported in PD. This study aimed to explore the neuroprotective effects and potential mechanisms of Aureusidin in PD. The present study demonstrated that Aureusidin protected SH-SY5Y cells from cell damage induced by 6-hydroxydopamine (6-OHDA) via inhibiting the mitochondria-dependent apoptosis and activating the Nrf2/HO-1 antioxidant signaling pathway. Additionally, Aureusidin diminished dopaminergic (DA) neuron degeneration induced by 6-OHDA and reduced the aggregation toxicity of α-synuclein (α-Syn) in Caenorhabditis elegans (C. elegans.) In conclusion, Aureusidin showed a neuroprotective effect in the 6-OHDA-induced PD model via activating Nrf2/HO-1 signaling pathway and prevented mitochondria-dependent apoptosis pathway, and these findings suggested that Aureusidin may be an effective drug for the treatment of PD.

The pharmacological effects of Berberine and its therapeutic potential in different diseases: Role of the phosphatidylinositol 3-kinase/AKT signaling pathway

The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway plays a central role in cell growth and survival and is disturbed in various pathologies. The PI3K is a kinase that generates phosphatidylinositol-3,4,5-trisphosphate (PI (3-5) P3), as a second messenger responsible for the translocation of AKT to the plasma membrane and its activation. However, due to the crucial role of the PI3K/AKT pathway in regulation of cell survival processes, it has been introduced as a main therapeutic target for natural compounds during the progression of different pathologies. Berberine, a plant-derived isoquinone alkaloid, is known because of its anti-inflammatory, antioxidant, antidiabetic, and antitumor properties. The effect of this natural compound on cell survival processes has been shown to be mediated by modulation of the intracellular pathways. However, the effects of this natural compound on the PI3K/AKT pathway in various pathologies have not been reviewed so far. Therefore, this paper aims to review the PI3K/AKT-mediated effects of Berberine in different types of cancer, diabetes, cardiovascular, and central nervous system diseases.

Integrated metabolomics and proteomics analysis of plasma lipid metabolism in Parkinson's disease

INTRODUCTION

Metabolomics and proteomics are two growing fields of science which may shed light on the molecular mechanisms that contribute to neurodegenerative diseases. Studies focusing on these aspects can reveal specific metabolites and proteins that can halt or reverse the progressive neurodegenerative process leading to dopaminergic cell death in the brain.

AREAS COVERED

In this article, an overview of the current status of metabolomic and proteomic profiling in the neurodegenerative disease such as Parkinson's disease (PD) is presented. We discuss the importance of state-of-the-art metabolomics and proteomics using advanced analytical methodologies and their potential for discovering new biomarkers in PD. We critically review the research to date, highlighting how metabolomics and proteomics can have an important impact on early disease diagnosis, future therapy development and the identification of new biomarkers. Finally, we will discuss interactions between lipids and α-synuclein (SNCA) and also consider the role of SNCA in lipid metabolism.

EXPERT OPINION

Metabolomic and proteomic studies contribute to understanding the biological basis of PD pathogenesis, identifying potential biomarkers and introducing new therapeutic strategies. The complexity and multifactorial nature of this disease requires a comprehensive approach, which can be achieved by integrating just these two omic studies.

Sesamol: A Phenolic Compound of Health Benefits and Therapeutic Promise in Neurodegenerative Diseases

Sesamol, one of the key bioactive ingredients of sesame seeds (Sesamum indicum L.), is responsible for many of its possible nutritional benefits. Both the Chinese and Indian medical systems have recognized the therapeutic potential of sesame seeds. It has been shown to have significant therapeutic potential against oxidative stress, inflammatory diseases, metabolic syndrome, neurodegeneration, and mental disorders. Sesamol is a benign molecule that inhibits the expression of inflammatory indicators like numerous enzymes responsible for inducing inflammation, protein kinases, cytokines, and redox status. This review summarises the potential beneficial effects of sesamol against neurological diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Recently, sesamol has been shown to reduce amyloid peptide accumulation and attenuate cognitive deficits in AD models. Sesamol has also been demonstrated to reduce the severity of PD and HD in animal models by decreasing oxidative stress and inflammatory pathways. The mechanism of sesamol's pharmacological activities against neurodegenerative diseases will also be discussed in this review.