Role of oxidative stress in Parkinson's disease

Discovery of potent LRRK2 inhibitors by ensemble virtual screening strategy and bioactivity evaluation

Leucine-rich repeat kinase 2 (LRRK2) has been reported to be associated with familial and idiopathic Parkinson's disease (PD) risk and is a promising target for drug discovery against PD. To identify novel and effective LRRK2 inhibitors, an ensemble virtual screening strategy by combining fingerprint similarity, complex-based pharmacophore and structure-based molecular docking was proposed and applied. Using this strategy, we finally selected 25 compounds from ∼1.7 million compounds for in vitro and in vivo tests. Firstly, the kinase inhibitory activity tests of compounds based on ADP-Glo assay identified three most potent compounds LY2023-19, LY2023-24 and LY2023-25 with IC50 of 556.4 nM, 218.1 nM and 22.4 nM for LRRK2 G2019S mutant, respectively. The further cellular experiments also indicated that three hit compounds significantly inhibited Ser935 phosphorylation of both wide-type and G2019S LRRK2 with IC50 ranging from 27 nM to 1674 nM in HEK293T cells. The MD simulations of three compounds and G2019S LRRK2 showed the hydrogen bond formed by Glu1948 and Ala1950 is crucial for the binding of LRRK2. Afterwards, 6-OHDA-induced PD zebrafish model was constructed to evaluate the neuroprotective effects of hit compounds. The locomotion of the 6-OHDA treated zebrafish larvae was improved after treatment with LY2023-24. The obtained results can provide valuable guidance for the development of PD drugs by targeting LRRK2.

Periplaneta americana L. extract exerts neuroprotective effects by inhibiting endoplasmic reticulum stress via AKT-dependent pathway in experimental models of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disorder that currently has no curable strategies. More and more evidence suggests that endoplasmic reticulum (ER) stress plays an essential role in PD pathogenesis. Periplaneta americana L. (P. americana) is a traditional Chinese medicine with diverse therapeutic properties. This study aims to investigate the neuroprotective effect and underlying mechanism of P. americana in in vitro and in vivo PD models.

METHODS

The exposure of SH-SY5Y cells to 1-methyl-4-phenyl-pyridinium (MPP+) was used as the in vitro PD model. MTT assay, Hoechst staining, Calcein AM-PI staining and flow cytometry were performed to measure the cell viability and apoptosis. DCFH-DA and JC-1 assay were used to measure the intracellular ROS and mitochondrial membrane potential (Δψm), respectively. Western-blot and immunostaining were conducted to detect the expression of key molecules related with ER stress. For the in vivo PD model induced by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydro-pyridine (MPTP), the motor function of mice was assessed by behavioral tests, the level of TH was examined by western-blot and immunostaining, the expression of key molecules related with ER stress was measured by western-blot.

RESULTS

Periplaneta americana ethanol extract (PAE) concentration-dependently inhibited MPP+-induced cell loss and increased cell viability. PAE also remarkably attenuated ROS accumulation, the decline of Δψm as well as the excessive ER stress. The neuroprotective effects of PAE could be blocked by ROS inducer trimethylamine N-Oxide or ER stress activator tunicaymycin, while the antioxidant N-Acetyl-L-cysteine or ER stress inhibitor sodium 4-phenylbutyrate mimicked the effects of PAE. Furthermore, we found that PAE could activate AKT/GSK3β/β-catenin pathway. The effect of PAE on ROS production, Δψm and ER stress was blocked by AKT inhibitor MK-2206. In in vivo model, PAE significantly improved motor function, prevented dopaminergic neuronal loss and attenuated ER stress in substantia nigra and striatum of MPTP-treated mice. Similarly, the effects of PAE on MPTP-treated mice were also abolished by MK-2206.

CONCLUSIONS

Our results suggest that P. americana exerts neuroprotective effects through inhibiting ER stress via AKT-dependent pathway. Periplaneta americana may represent a promising therapeutic agent for PD treatment and is worthy of further being exploited.

New opportunities for antioxidants in amelioration of neurodegenerative diseases

This comprehensive review elucidates the critical role of antioxidants to mitigate oxidative stress, a common denominator in an array of neurodegenerative disorders. Oxidative stress-induced damage has been linked to the development of diseases such as Alzheimer's, Parkinson's, Huntington's disease and amyotrophic lateral sclerosis. This article examines a wide range of scientific literature and methodically delineates the several methods by which antioxidants exercise their neuroprotective benefits. It also explores into the complex relationship between oxidative stress and neuroinflammation, focusing on how antioxidants can alter signaling pathways and transcription factors to slow neurodegenerative processes. Key antioxidants, such as vitamins C and E, glutathione, and polyphenolic compounds, are tested for their ability to combat reactive oxygen and nitrogen species. The dual character of antioxidants, which operate as both direct free radical scavengers and regulators of cellular redox homeostasis, is investigated in terms of therapeutic potential. Furthermore, the study focuses on new antioxidant-based therapy techniques and their mechanisms including Nrf-2, PCG1α, Thioredoxin etc., which range from dietary interventions to targeted antioxidant molecules. Insights into ongoing clinical studies evaluating antioxidant therapies in neurodegenerative illnesses offer an insight into the translational potential of antioxidant research. Finally, this review summarizes our present understanding of antioxidant processes in neurodegenerative illnesses, providing important possibilities for future study and treatment development.

Antiparkinson potential of khellin on rotenone-induced Parkinson's disease in a zebrafish model: targeting MAO, inflammatory, and oxidative stress markers with molecular docking, MD simulations, and histopathology evidence

In this study, the antiparkinson effect of khellin (KL) on rotenone-induced Parkinson's disease (PD) was examined in zebrafish. Initially, In silico evaluations, such as drug likeness and ADME/T analysis, confirmed the pharmacological viability of KL. Molecular docking and molecular dynamics (MD) analysis revealed stable binding interactions between KL and monamine oxidase B (MAO-B). Molecular docking results for KL and pioglitazone (CCl) revealed binding energies of -6.5 and -10.4 kcal/mol, respectively. Later, molecular dynamics (MD) studies were performed to assess the stability of these complexes, which yielded binding energies of -36.04 ± 55.21 and -56.2 ± 80.63 kJ/mol for KL and CCl, respectively. These results suggest that KL exhibits considerable binding affinity for MAO-B. In In vitro studies, according to the DPPH free radical scavenging assay, KL exhibited significant antioxidant effects, indicating that it can promote redox balance with an IC50 value of 22.68 ± 0.5 μg/ml. In vivo studies and evaluation of locomotor activity, social interaction, histopathology and biochemical parameters were conducted in KL-treated zebrafish to measure SOD and GSH antioxidant activity, the oxidative stress marker malondialdehyde (MDA), the inflammatory marker myeloperoxidase (MPO) and MAO-B. However, while the locomotor and social interaction abilities of the rotenone-treated zebrafish were significantly reduced, KL treatment significantly improved locomotor activity (p < 0.001) and social interaction (p < 0.001). KL alleviated PD symptoms, as indicated by significant increases in SOD (p < 0.01), GSH (p < 0.001), MDA (p < 0.001), MAO-B (p < 0.001) and MPO (p < 0.001) in rotenone-induced PD fish (p<0.001) significantly reduced activities. Histopathological studies revealed that rotenone-induced brain hyperintensity and abnormal cellularity of the periventricular gray matter in the optic tectum were significantly reduced by KL treatment. This study provides a strong basis for developing KL as a new candidate for the treatment of Parkinson's disease, with the prospect of improved safety profiles and efficacy.

Effects of quercetin in preclinical models of Parkinson's disease: A systematic review

Parkinson's disease (PD) is a neurodegenerative disease that affects dopaminergic neurons, thus impairing dopaminergic signalling. Quercetin (QUE) has antioxidant and neuroprotective properties that are promising for the treatment of PD. This systematic review aimed to investigate the therapeutic effects of QUE against PD in preclinical models. The systematic search was performed in PubMed, Scopus and Web of Science. At the final screening stage, 26 articles were selected according to pre-established criteria. Selected studies used different methods for PD induction, as well as animal models. Most studies used rats (73.08%) and mice (23.08%), with 6-OHDA as the main strategy for PD induction (38.6%), followed by rotenone (30.8%). QUE was tested immersed in oil, nanosystems or in free formulations, in varied routes of administration and doses, ranging from 10 to 400 mg/kg and from 5 to 200 mg/kg in oral and intraperitoneal administrations, respectively. Overall, evidence from published data suggests a potential use of QUE as a treatment for PD, mainly through the inhibition of oxidative stress, neuroinflammatory response and apoptotic pathways.

Neurotoxicity of Some Environmental Pollutants to Zebrafish

The aquatic environment encompasses a wide variety of pollutants, from plastics to drug residues, pesticides, food compounds, and other food by-products, and improper disposal of waste is the main cause of the accumulation of toxic substances in water. Monitoring, assessing, and attempting to control the effects of contaminants in the aquatic environment are necessary and essential to protect the environment and thus human and animal health, and the study of aquatic ecotoxicology has become topical. In this respect, zebrafish are used as model organisms to study the bioaccumulation, toxicity, and influence of environmental pollutants due to their structural, functional, and material advantages. There are many similarities between the metabolism and physiological structures of zebrafish and humans, and the nervous system structure, blood-brain barrier function, and social behavior of zebrafish are characteristics that make them an ideal animal model for studying neurotoxicity. The aim of the study was to highlight the neurotoxicity of nanoplastics, microplastics, fipronil, deltamethrin, and rotenone and to highlight the main behavioral, histological, and oxidative status changes produced in zebrafish exposed to them.

The role of voltage-gated calcium channels in the pathogenesis of Parkinson's disease

Aim: Voltage-gated calcium (CaV) channels play an essential role in maintaining calcium homeostasis and regulating numerous physiological processes in neurons. Therefore, dysregulation of calcium signaling is relevant in many neurological disorders, including Parkinson's disease (PD). This review aims to introduce the role of CaV channels in PD and discuss some novel aspects of channel regulation and its impact on the molecular pathophysiology of the disease.

Methods: an exhaustive search of the literature in the field was carried out using the PubMed database of The National Center for Biotechnology Information. Systematic searches were performed from the initial date of publication to May 2022.

Results: Although α-synuclein aggregates are the main feature of PD, L-type calcium (CaV1) channels seem to play an essential role in the pathogenesis of PD. Changes in the functional expression of CaV1.3 channels alter Calcium homeostasis and contribute to the degeneration of dopaminergic neurons. Furthermore, recent studies suggest that CaV channel trafficking towards the cell membrane depends on the activity of the ubiquitin-proteasome system (UPS). In PD, there is an increase in the expression of L-type channels associated with a decrease in the expression of Parkin, an E3 enzyme of the UPS. Therefore, a link between Parkin and CaV channels could play a fundamental role in the pathogenesis of PD and, as such, could be a potentially attractive target for therapeutic intervention.

Conclusion: The study of alterations in the functional expression of CaV channels will provide a framework to understand better the neurodegenerative processes that occur in PD and a possible path toward identifying new therapeutic targets to treat this condition.

Biochemical properties and biological potential of Syzygium heyneanum with antiparkinson's activity in paraquat induced rodent model

Syzygium heyneanum is a valuable source of flavonoids and phenols, known for their antioxidant and neuroprotective properties. This research aimed to explore the potential of Syzygium heyneanum ethanol extract (SHE) in countering Parkinson's disease. The presence of phenols and flavonoids results in SHE displaying an IC50 value of 42.13 when assessed in the DPPH scavenging assay. Rats' vital organs (lungs, heart, spleen, liver, and kidney) histopathology reveals little or almost no harmful effect. The study hypothesized that SHE possesses antioxidants that could mitigate Parkinson's symptoms by influencing α-synuclein, acetylcholinesterase (AChE), TNF-α, and IL-1β. Both in silico and in vivo investigations were conducted. The Parkinson's rat model was established using paraquat (1 mg/kg, i.p.), with rats divided into control, disease control, standard, and SHE-treated groups (150, 300, and 600 mg/kg) for 21 days. According to the ELISA statistics, the SHE treated group had lowers levels of IL-6 and TNF-α than the disease control group, which is a sign of neuroprotection. Behavioral and biochemical assessments were performed, alongside mRNA expression analyses using RT-PCR to assess SHE's impact on α-synuclein, AChE, TNF-α, and interleukins in brain homogenates. Behavioral observations demonstrated dose-dependent improvements in rats treated with SHE (600 > 300 > 150 mg/kg). Antioxidant enzyme levels (catalase, superoxide dismutase, glutathione) were significantly restored, particularly at a high dose, with notable reduction in malondialdehyde. The high dose of SHE notably lowered acetylcholinesterase levels. qRT-PCR results indicated reduced mRNA expression of IL-1β, α-synuclein, TNF-α, and AChE in SHE-treated groups compared to disease controls, suggesting neuroprotection. In conclusion, this study highlights Syzygium heyneanum potential to alleviate Parkinson's disease symptoms through its antioxidant and modulatory effects on relevant biomarkers.

Sustained Systemic Antioxidative Effects of Intermittent Theta Burst Stimulation beyond Neurodegeneration: Implications in Therapy in 6-Hydroxydopamine Model of Parkinson's Disease

Parkinson's disease (PD) is manifested by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and caudoputamen (Cp), leading to the development of motor and non-motor symptoms. The contribution of oxidative stress to the development and progression of PD is increasingly recognized. Experimental models show that strengthening antioxidant defenses and reducing pro-oxidant status may have beneficial effects on disease progression. In this study, the neuroprotective potential of intermittent theta burst stimulation (iTBS) is investigated in a 6-hydroxydopamine (6-OHDA)-induced PD model in rats seven days after intoxication which corresponds to the occurrence of first motor symptoms. Two-month-old male Wistar rats were unilaterally injected with 6-OHDA to mimic PD pathology and were subsequently divided into two groups to receive either iTBS or sham stimulation for 21 days. The main oxidative parameters were analyzed in the caudoputamen, substantia nigra pars compacta, and serum. iTBS treatment notably mitigated oxidative stress indicators, simultaneously increasing antioxidative parameters in the caudoputamen and substantia nigra pars compacta well after 6-OHDA-induced neurodegeneration process was over. Serum analysis confirmed the systemic effect of iTBS with a decrease in oxidative markers and an increase in antioxidants. Prolonged iTBS exerts a modulatory effect on oxidative/antioxidant parameters in the 6-OHDA-induced PD model, suggesting a potential neuroprotective benefit, even though at this specific time point 6-OHDA-induced oxidative status was unaltered. These results emphasize the need to further explore the mechanisms of iTBS and argue in favor of considering it as a therapeutic intervention in PD and related neurodegenerative diseases.

Impact of NQO1 dysregulation in CNS disorders

NAD(P)H Quinone Dehydrogenase 1 (NQO1) plays a pivotal role in the regulation of neuronal function and synaptic plasticity, cellular adaptation to oxidative stress, neuroinflammatory and degenerative processes, and tumorigenesis in the central nervous system (CNS). Impairment of the NQO1 activity in the CNS can result in abnormal neurotransmitter release and clearance, increased oxidative stress, and aggravated cellular injury/death. Furthermore, it can cause disturbances in neural circuit function and synaptic neurotransmission. The abnormalities of NQO1 enzyme activity have been linked to the pathophysiological mechanisms of multiple neurological disorders, including Parkinson's disease, Alzheimer's disease, epilepsy, multiple sclerosis, cerebrovascular disease, traumatic brain injury, and brain malignancy. NQO1 contributes to various dimensions of tumorigenesis and treatment response in various brain tumors. The precise mechanisms through which abnormalities in NQO1 function contribute to these neurological disorders continue to be a subject of ongoing research. Building upon the existing knowledge, the present study reviews current investigations describing the role of NQO1 dysregulations in various neurological disorders. This study emphasizes the potential of NQO1 as a biomarker in diagnostic and prognostic approaches, as well as its suitability as a target for drug development strategies in neurological disorders.

Enlarged Perivascular Space and Index for Diffusivity Along the Perivascular Space as Emerging Neuroimaging Biomarkers of Neurological Diseases

The existence of lymphatic vessels or similar clearance systems in the central nervous system (CNS) that transport nutrients and remove cellular waste is a neuroscientific question of great significance. As the brain is the most metabolically active organ in the body, there is likely to be a potential correlation between its clearance system and the pathological state of the CNS. Until recently the successive discoveries of the glymphatic system and the meningeal lymphatics solved this puzzle. This article reviews the basic anatomy and physiology of the glymphatic system. Imaging techniques to visualize the function of the glymphatic system mainly including post-contrast imaging techniques, indirect lymphatic assessment by detecting increased perivascular space, and diffusion tensor image analysis along the perivascular space (DTI-ALPS) are discussed. The pathological link between glymphatic system dysfunction and neurological disorders is the key point, focusing on the enlarged perivascular space (EPVS) and the index of diffusivity along the perivascular space (ALPS index), which may represent the activity of the glymphatic system as possible clinical neuroimaging biomarkers of neurological disorders. The pathological link between glymphatic system dysfunction and neurological disorders is the key point, focusing on the enlarged perivascular space (EPVS) and the index for of diffusivity along the perivascular space (ALPS index), which may represent the activity of the glymphatic system as possible clinical neuroimaging biomarkers of neurological disorders.

A dual-responsive ratiometric indicator designed for in vivo monitoring of oxidative stress and antioxidant capacity

The imbalance between oxidative stress and antioxidant capacity is strongly associated with the development of numerous degenerative diseases, including cardiovascular diseases, diabetes, neurodegenerative diseases, and cancer. Therefore, monitoring oxidative stress and antioxidant capacity in vivo is crucial for maintaining cellular homeostasis and the stability of the organism's internal environment. Here, we present the findings of our study on DQ1, a dual-responsive indicator designed specifically for imaging H2O2 and NAD(P)H, which are critical indicators of oxidative stress and antioxidant capacity. DQ1 facilitated the colorimetric and fluorescence detection of H2O2 and NAD(P)H in two well-separated channels, exhibiting a detection limit of 1.0 μM for H2O2 and 0.21 nM for NAD(P)H, respectively. Experiments conducted on living cells and zebrafish demonstrated that DQ1 could effectively detect changes in H2O2 and NAD(P)H levels when exposed to exogenous hypoxic conditions and chemical stimuli. Furthermore, the effectiveness of the as-fabricated indicator was investigated in two distinct mouse models: evaluating H2O2 and NAD(P)H levels in myocardial cell dysfunction during acute myocardial infarction and liver tissue damage under trichloroethylene stress conditions. In vivo experiments demonstrated that the levels of the two cardiac biomarkers increase progressively with the development of myocardial infarction, eventually reaching a steady state after 7 days when the damaged cells in the infarcted region become depleted. Moreover, during 14 continuous days of exposure to trichloroethylene, the two biomarkers in liver tissue exhibited a sustained increase, indicating a significant enhancement in intracellular oxidative stress and antioxidant capacity attributed to the mouse liver's robust metabolic capacity. The aforementioned studies underscore the efficacy of DQ1 as a valuable tool for scrutinizing redox states at both the single-cell and biological tissue levels. It presents significant potential for investigating the dynamic alternations in oxidative stress and antioxidant capacity within disease models as the disease progresses, thereby facilitating a more profound comprehension of these processes across various disease models.

Effects of fluoride on oxidative DNA damage, nitric oxide level, lipid peroxidation and cholinesterase enzyme activity in a rotenone-induced experimental Parkinson's model

OBJECTIVE

Environmental toxins are known to be one of the important factors in the development of Parkinson's disease (PD). This study was designed to investigate the possible contribution of fluoride (F) exposure to oxidative stress and neurodegeneration in rats with PD induced by rotenone (ROT).

MATERIALS AND METHODS

A total of 72 Wistar albino male rats were used in the experiment and 9 groups were formed with 8 animals in each group. ROT (2 mg/kg) was administered subcutaneously (sc) for 28 days. Different doses of sodium fluoride (NaF) (25, 50 and 100 ug/mL) were given orally (po) for 4 weeks. Malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO), oxidative DNA damage (8-OHdG) and cholinesterase (AChE/BChE) enzyme activities were evaluated in serum and brain tissue homogenates.

RESULTS

Rats treated with ROT and NaF had significant increases in serum and brain MDA, NO content, and decreases in GSH. In addition, the combination of ROT and NaF triggered oxidative DNA damage and resulted in increased AChE/BChE activity.

CONCLUSIONS

Findings suggest that NaF and ROT may interact synergistically leading to oxidative damage and neuronal cell loss. As a result, we believe that exposure to pesticides in combination with NaF is one of the environmental factors that should not be ignored in the etiology of neurological diseases such as PD in populations in areas with endemic fluorosis.

SIRT1-dependent mitochondrial biogenesis supports therapeutic effects of vidarabine against rotenone-induced neural cell injury

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, which is distinguished by the loss of dopaminergic (DA) neurons in the substantia nigra and the formation of intraneuronal. Numerous studies showed that the damage and dysfunction of mitochondria may play key roles in DA neuronal loss. Thus, it is necessary to seek therapeutic measures for PD targeting mitochondrial function and biogenesis. In this study, through screening the purchased compound library, we found that marine derived vidarabine had significant neuroprotective effects against rotenone (ROT) induced SH-SY5Y cell injury. Further studies indicated that vidarabine pretreatment significantly protected ROT-treated SH-SY5Y cells from toxicity by preserving mitochondrial morphology, improving mitochondrial function, and reducing cell apoptosis. Vidarabine also reduced the oxidative stress and increased the expression levels of PGC-1α, NRF1, and TFAM proteins, which was accompanied by the increased mitochondrial biogenesis. However, the neuroprotective effects of vidarabine were counteracted in the presence of SIRT1-specific inhibitor Ex-527. Besides, vidarabine treatment attenuated the weight loss, alleviated the motor deficits and inhibited the neuronal injury in the MPTP induced mouse model. Thus, vidarabine may exert neuroprotective effects via a mechanism involving specific connections between the SIRT1-dependent mitochondrial biogenesis and its antioxidant capacity, suggesting that vidarabine has potential to be developed into a novel therapeutic agent for PD.

Neuroprotective effect of chlorogenic acid on Parkinson's disease like symptoms through boosting the autophagy in zebrafish

Parkinson's disease (PD) is characterized by both motor and non-motor symptoms, including hypokinesia, postural instability, dopaminergic (DA) neurons loss, and α-synuclein (α-syn) accumulation. A growing number of patients show negative responses towards the current therapies. Thus, preventative or disease-modifying treatment agents are worth to further research. In recent years, compounds extracted from natural sources become promising candidates to treat PD. Chlorogenic acid (CGA) is a phenolic compound appearing in coffee, honeysuckle, and eucommia that showed their potential as antioxidants and neuroprotectors. In this study, we investigated the anti-PD activity of CGA by testing its effect on 1-methyl-4-phenyl-1-1,2,3,6-tetrahydropyridine (MPTP) zebrafish model of PD. It was shown that CGA relieved MPTP-induced PD-like symptoms including DA neurons and blood vessel loss, locomotion reduction, and apoptosis events in brain. Moreover, CGA modulated the expression of PD- and autophagy-related genes (α-syn, lc3b, p62, atg5, atg7, and ulk1b), showing its ability to promote the autophagy which was interrupted in the PD pathology. The unblocked effect of CGA on autophagy was further verified in 6-hydroxydopamine (6-OHDA)-modeled SHSY5Y cells. Our findings indicated that CGA might relieve PD by boosting the autophagy in neuronal cells that makes CGA a potential candidate for anti-PD treatment.

Nickel and aluminium mixture elicit memory impairment by activation of oxidative stress, COX-2, and diminution of AChE, BDNF and NGF levels in cerebral cortex and hippocampus of male albino rats

This study evaluated nickel and aluminium-induced neurotoxicity, as a binary metal mixture. Twenty-eight male Sprague Dawley albino rats were weight-matched and divided into four groups. Group 1 (control) received deionized water. Group 2 and 3 received Aluminium (1 mg/kg) and Nickel (0.2 mg/kg) respectively, while Group 4 received Ni and Al mixture HMM three times a week orally for 90 days. Barnes maze tests was performed. Rats were sacrificed under pentobarbital anaesthesia, cerebral cortex and hippocampus were separated, and metal levels were measured using Atomic Absorption Spectroscopy (AAS). Malondialdehyde (MDA), catalase (CAT), glutathione content (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), Brain Derived Neurotrophic Factor (BDNF), Nerve growth factor NGF, cyclo-oxygenase COX-2 and Acetylcholinesterase (AChE) were assayed using ELISA kits. Ni/Al binary mixture exposed rats showed a shorter latency period (though not significant) of 3.21 ± 1.40 s in comparison to 3.77 ± 1.11 (Ni only) and 3.99 ± 1.16(Al only). Ni/Al mixture gp had the lowest levels of Mg in both the hippocampus and frontal cortex when compared with the individual metals. In the hippocampus Al only exposed rats significantly showed p < 0.05 higher iron and Ca levels in comparison to Ni/Al mixture. Al alone significantly showed p < 0.05 lower levels of Fe but higher Ca than the Ni/Al mixture group. Exposure to Al only showed lower levels of BDNF in comparison to Ni/Al combination, whereas Ni/Al mixture gp had lower levels of NGF in comparison to the individual metals in the hippocampus. In the frontal cortex Ni only, group showed significantly lower BDNF in comparison to Ni/Al mixture whereas the mixture showed significantly lower NGF when compared with Al only group. There were higher levels of COX-2 in the Ni/Al mixture than individual metal treated rats in both hippocampus and frontal cortex. AChE levels in the Ni/Al mixture group was higher than Ni or Al only gps in the hippocampus whereas in the frontal cortex, Ni/Al exposed rats showed significantly lower AChE levels in comparison to Al only group. Ni, Al and Ni/Al mixture exhibited memory impairment by activation of oxidative stress, COX-2, and diminution of AChE, BDNF and NGF levels in cerebral cortex and hippocampus. The BDNF-COX-2 AChE signalling pathway may be involved in the neurotoxicity of Ni and Al.

Obstructive sleep apnea in Parkinson's disease: A prevalent, clinically relevant and treatable feature

Parkinson's disease (PD) is a chronic neurodegenerative disease characterized by motor and non-motor symptoms, including obstructive sleep apnea (OSA), a common comorbid sleep disorder. The prevalence of OSA in PD is high, and its impact on quality of life, accident risk, and limited treatment options underscores the need for vigilant monitoring and effective interventions. OSA is observed in 20-70% of PD patients, whereas the general population exhibits a lower prevalence ranging from 2 to 14%. These discrepancies in prevalence may be attributed to differences in demographic characteristics, sample sizes with selection bias, and variations in scoring systems for apnea and hypopnea events used across different studies. This review highlights the potential pathogenesis of comorbid OSA in PD and provides an overview of ongoing clinical trials investigating interventions for this condition. Several mechanisms have been implicated in the development of OSA in PD, including intermittent hypoxemia, sleep fragmentation, alterations in the glymphatic system homeostasis, upper airway obstruction, and inflammation. Given the adverse effects of PD comorbid OSA, early intervention measures are crucial. It is imperative to conduct longitudinal studies and clinical trials to elucidate the pathogenesis and develop novel and effective interventions for OSA in PD patients. These efforts aim to delay the progression of PD, enhance patients' quality of life, and alleviate the burden on society and families.

Mild hypoxia-induced structural and functional changes of the hippocampal network

Hypoxia causes structural and functional changes in several brain regions, including the oxygen-concentration-sensitive hippocampus. We investigated the consequences of mild short-term hypoxia on rat hippocampus in vivo. The hypoxic group was treated with 16% O2 for 1 h, and the control group with 21% O2. Using a combination of Gallyas silver impregnation histochemistry revealing damaged neurons and interneuron-specific immunohistochemistry, we found that somatostatin-expressing inhibitory neurons in the hilus were injured. We used 32-channel silicon probe arrays to record network oscillations and unit activity from the hippocampal layers under anaesthesia. There were no changes in the frequency power of slow, theta, beta, or gamma bands, but we found a significant increase in the frequency of slow oscillation (2.1-2.2 Hz) at 16% O2 compared to 21% O2. In the hilus region, the firing frequency of unidentified interneurons decreased. In the CA3 region, the firing frequency of some unidentified interneurons decreased while the activity of other interneurons increased. The activity of pyramidal cells increased both in the CA1 and CA3 regions. In addition, the regularity of CA1, CA3 pyramidal cells' and CA3 type II and hilar interneuron activity has significantly changed in hypoxic conditions. In summary, a low O2 environment caused profound changes in the state of hippocampal excitatory and inhibitory neurons and network activity, indicating potential changes in information processing caused by mild short-term hypoxia.

Neurological Insights into Sleep Disorders in Parkinson's Disease

Parkinson's disease (PD) is a common multidimensional neurological disorder characterized by motor and non-motor features and is more prevalent in the elderly. Sleep disorders and cognitive disturbances are also significant characteristics of PD. Sleep is an important physiological process for normal human cognition and physical functioning. Sleep deprivation negatively impacts human physical, mental, and behavioral functions. Sleep disturbances include problems falling asleep, disturbances occurring during sleep, abnormal movements during sleep, insufficient sleep, and excessive sleep. The most recognizable and known sleep disorders, such as rapid-eye-movement behavior disorder (RBD), insomnia, excessive daytime sleepiness (EDS), restless legs syndrome (RLS), sleep-related breathing disorders (SRBDs), and circadian-rhythm-related sleep-wake disorders (CRSWDs), have been associated with PD. RBD and associated emotional disorders are common non-motor symptoms of PD. In individuals, sleep disorders and cognitive impairment are important prognostic factors for predicting progressing neurodegeneration and developing dementia conditions in PD. Studies have focused on RBD and its associated neurological changes and functional deficits in PD patients. Other risks, such as cognitive decline, anxiety, and depression, are related to RBD. Sleep-disorder diagnosis is challenging, especially in identifying the essential factors that disturb the sleep-wake cycle and the co-existence of other concomitant sleep issues, motor symptoms, and breathing disorders. Focusing on sleep patterns and their disturbances, including genetic and other neurochemical changes, helps us to better understand the central causes of sleep alterations and cognitive functions in PD patients. Relations between α-synuclein aggregation in the brain and gender differences in sleep disorders have been reported. The existing correlation between sleep disorders and levels of α-synuclein in the cerebrospinal fluid indicates the risk of progression of synucleinopathies. Multidirectional approaches are required to correlate sleep disorders and neuropsychiatric symptoms and diagnose sensitive biomarkers for neurodegeneration. The evaluation of sleep pattern disturbances and cognitive impairment may aid in the development of novel and effective treatments for PD.

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Insights into the Lysine Acetylome of the Haloarchaeon Haloferax volcanii during Oxidative Stress by Quantitative SILAC-Based Proteomics

Oxidative stress adaptation strategies are important to cell function and are linked to cardiac, neurodegenerative disease, and cancer. Representatives of the Archaea domain are used as model organisms based on their extreme tolerance to oxidants and close evolutionary relationship with eukaryotes. A study of the halophilic archaeon Haloferax volcanii reveals lysine acetylation to be associated with oxidative stress responses. The strong oxidant hypochlorite: (i) stimulates an increase in lysine acetyltransferase HvPat2 to HvPat1 abundance ratios and (ii) selects for lysine deacetylase sir2 mutants. Here we report the dynamic occupancy of the lysine acetylome of glycerol-grown H. volcanii as it shifts in profile in response to hypochlorite. These findings are revealed by the: (1) quantitative multiplex proteomics of the SILAC-compatible parent and Δsir2 mutant strains and (2) label-free proteomics of H26 'wild type' cells. The results show that lysine acetylation is associated with key biological processes including DNA topology, central metabolism, cobalamin biosynthesis, and translation. Lysine acetylation targets are found conserved across species. Moreover, lysine residues modified by acetylation and ubiquitin-like sampylation are identified suggesting post-translational modification (PTM) crosstalk. Overall, the results of this study expand the current knowledge of lysine acetylation in Archaea, with the long-term goal to provide a balanced evolutionary perspective of PTM systems in living organisms.

Intranasal cerium oxide nanoparticles improves locomotor activity and reduces oxidative stress and neuroinflammation in haloperidol-induced parkinsonism in rats

Introduction: Cerium oxide nanoparticles (CONPs) have been investigated for their therapeutic potential in Parkinson's disease (PD) due to their potent and regenerative antioxidant activity. In the present study, CONPs were used to ameliorate the oxidative stress caused by free radicals in haloperidol-induced PD in rats following intranasal administration. Method: The antioxidant potential of the CONPs was evaluated in vitro using ferric reducing antioxidant power (FRAP) assay. The penetration and local toxicity of the CONPs was evaluated ex-vivo using goat nasal mucosa. The acute local toxicity of intranasal CONPs was also studied in rat. Gamma scintigraphy was used to assess the targeted brain delivery of CONPs. Acute toxicity studies were performed in rats to demonstrate safety of intranasal CONPs. Further, open field test, pole test, biochemical estimations and brain histopathology was performed to evaluate efficacy of intranasal CONPs in haloperidol-induced PD rat model. Results: The FRAP assay revealed highest antioxidant activity of prepared CONPs at a concentration of 25 μg/mL. Confocal microscopy showed deep and homogenous distribution of CONPs in the goat nasal mucus layers. No signs of irritation or injury were seen in goat nasal membrane when treated with optimized CONPs. Scintigraphy studies in rats showed targeted brain delivery of intranasal CONPs and acute toxicity study demonstrated safety. The results of open field and pole test showed highly significant (p < 0.001) improvement in locomotor activity of rats treated with intranasal CONPs compared to untreated rats. Further, brain histopathology of treatment group rats showed reduced neurodegeneration with presence of more live cells. The amount of thiobarbituric acid reactive substances (TBARS) was reduced significantly, whereas the levels of catalase (CAT), superoxide dismutase (SOD), and GSH were increased significantly, while amounts of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) showed significant reduction after intranasal administration of CONPs. Also, the intranasal CONPs, significantly high (p < 0.001) dopamine concentration (13.93 ± 0.85 ng/mg protein) as compared to haloperidol-induced control rats (5.76 ± 0.70 ng/mg protein). Conclusion: The overall results concluded that the intranasal CONPs could be safe and effective therapeutics for the management of PD.

The Transcription Factor Nrf2 Mediates the Effects of Antrodia camphorata Extract on Neuropathological Changes in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a disorder that is characterized by progressive and selective neuronal injury and cell death. Recent studies have provided accumulating evidence for a significant role of the immune system and neuroinflammation in PD pathogenesis. On this basis, many scientific articles have highlighted the anti-inflammatory and neuroprotective properties of Antrodia camphorata (AC), an edible fungus containing various bioactive compounds. This study aimed to evaluate the inhibitory effect of AC administration on neuroinflammation and oxidative stress in a murine model of MPTP-induced dopaminergic degeneration. AC (10, 30, 100 mg/kg) was administered daily by oral gavage starting 24 h after the first administration of MPTP, and mice were sacrificed 7 days after MPTP induction. In this study, treatment with AC significantly reduced the alteration of PD hallmarks, increasing tyrosine hydroxylase expression and reducing the number of alpha-synuclein-positive neurons. In addition, AC treatment restored the myelination process of neurons associated with PD and attenuated the neuroinflammatory state. Furthermore, our study demonstrated that AC was able to reduce the oxidative stress induced by MPTP injection. In conclusion, this study highlighted that AC could be a potential therapeutic agent for the treatment of neurodegenerative disorders such as PD.

Radical Scavenging Mechanisms of 1-Arylhydrazone Benzimidazole Hybrids with Neuroprotective Activity

Benzimidazole-arylhydrazone hybrids showed promising potential as multifunctional drugs for the treatment of neurodegenerative disorders. The neuroprotection studies conducted using an in vitro model of H₂O₂-induced oxidative stress on the SH-SY5Y cell line revealed a remarkable activity of the compound possessing a vanilloid structural fragment. The cell viability was preserved up to 84% and this effect was significantly higher than the one exerted by the reference compounds melatonin and rasagiline. Another compound with a catecholic moiety demonstrated the second-best neuroprotective activity. Computational studies were further conducted to characterize in depth the antioxidant properties of both compounds. The possible radical scavenging mechanisms were estimated as well as the most reactive sites through which the compounds may deactivate a variety of free radicals. Both of the compounds are able to deactivate not only the highly reactive hydroxyl radicals but also alkoxyl and hydroperoxyl radicals, following hydrogen atom transfer or radical adduct formation mechanism. In nonpolar medium, 3e is predicted to react slightly faster than 3a with alkoxyl radicals and around two orders of magnitude faster than 3a with hydroperoxyl radicals. The most reactive sites for formal hydrogen atom transfer in 3a are the meta-hydroxy group in the phenyl ring in water and the amide N-H group in benzene; in 3e, the amide N-H group is more reactive in both solvents. The radical adduct formation can occur at several positions in 3a and 3e, the most active being C4, C6, and C14. The stability of the formed radicals was estimated by NBO calculations. The NBO calculations indicated that the spin density in the radicals formed by the abstraction of a hydrogen atom from the amide groups of both compounds is delocalized over the phenyl ring and the hydrazone chain. The obtained theoretical data for the better radical scavenging ability of the vanilloid hybrid corroborate its experimentally established better neuroprotective activity.

Regioselective syntheses of 2-oxopyridine carbonitrile derivatives and evaluation for antihyperglycemic and antioxidant potential

A library of 2-oxopyridine carbonitriles 1-34 was synthesized by regioselective nucleophilic substitution reactions. In the first step, a one-pot multicomponent reaction yield pyridone intermediates. The resulting pyridone intermediates were then reacted with phenacyl halides in DMF and stirred at 100 °C for an hour to afford the desired compounds in good yields. Structures of synthetic molecules were characterized by EI-MS, HREI-MS, ¹H NMR, and ¹³C NMR, and all thirty-four (34) compounds were found to be new. All synthetic compounds were examined for antidiabetic and antioxidant potential. The compounds exhibited α-glucosidase inhibitory potential in the range of IC₅₀ = 3.00 ± 0.11-43.35 ± 0.67 μM and α-amylase inhibition potential in the range of IC₅₀ = 9.20 ± 0.14-65.56 ± 1.05 μM. Among the tested compounds, 1 showed the most significant α-glucosidase inhibitory activity, with an IC₅₀ value of 3.00 ± 0.11 μM, while the most active compound against α-amylase was 6, with an IC₅₀ value = 9.20 ± 0.14 μM. The kinetic studies and analysis indicated that the compounds followed the competitive mode of inhibition. In addition, the molecular docking studies showed the interaction profile of all molecules with the binding site residues of α-glucosidase and α-amylase enzymes.

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

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

Transcriptomic analysis: the protection of over-expression thioredoxin reductase 1 in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease. The pathologic characteristic feature is the loss of dopaminergic neurons in the substantia nigra (SN). However, the biochemical mechanisms are unclear. A large number of studies have shown that oxidative damage is the primary cause of PD. Hence, antioxidants could become a suitable option to treat PD. The thioredoxin (Trx) system represents a useful, potentially disease-relevant oxidation-reduction system. Thioredoxin reductase 1 (TR1) is a significant component of the Trx system.

METHODS

The overexpression lentivirus (LV) or LV-TR1 in the TR1-A53T model of PD by the stereotactic brain, and successful overexpression of LV or LV-TR1 in the MPP⁺-induced cellular model by LV or LV-TR1 transfection.

RESULTS

We confirmed that interleukin-7 mRNA levels increased in MPP⁺ compared to that in the control and MPP⁺-TR1 groups using quantitative polymerase chain reaction. The γ-H₂AX level was increased in the Tg-A53T group compared to that in the TR1-A53T group by western blotting. The expression of Na⁺-K⁺-ATP was decreased in the MPP⁺ group compared to that in the control and MPP⁺-TR1 groups by high content screening. Tg-A53T(the C57BL/6 mice transferred with mutant human a-syn); TR1-A53T(A53T mice which were injected TR1-LV 2 µl in SNc on two sides with minipump).The mice were fed for 10 months. control (the N2a cells cultivated with DMEM); MPP⁺(the N2a cells dealt with MPP⁺(1 mM) 48 h), MPP⁺-LV (the N2a cells over-expressed LV for 24 h then dealt with MPP⁺(1 mM) 48 h). MPP⁺-TR1(the N2a cell over-expressed TR1-LV for 24 h then dealt with MPP⁺(1 mM) 48 h). From the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, we confirmed that the overexpression of TR1 in SN pars compacta cells decreased oxidative stress, apoptosis, DNA damage, and inflammatory response and increased NADPH, Na⁺-K⁺-ATP, and immune response in this PD model.

CONCLUSIONS

Our study shows that overexpressed TR1 can be developed as a neuroprotective agent for PD. Therefore, our findings demonstrate a new targeted protein for the treatment of PD.

Mitochondrial Dysfunction and Parkinson's Disease: Pathogenesis and Therapeutic Strategies

Parkinson's disease (PD) is a common age-related neurodegenerative disorder whose pathogenesis is not completely understood. Mitochondrial dysfunction and increased oxidative stress have been considered as major causes and central events responsible for the progressive degeneration of dopaminergic (DA) neurons in PD. Therefore, investigating mitochondrial disorders plays a role in understanding the pathogenesis of PD and can be an important therapeutic target for this disease. This study discusses the effect of environmental, genetic and biological factors on mitochondrial dysfunction and also focuses on the mitochondrial molecular mechanisms underlying neurodegeneration, and its possible therapeutic targets in PD, including reactive oxygen species generation, calcium overload, inflammasome activation, apoptosis, mitophagy, mitochondrial biogenesis, and mitochondrial dynamics. Other potential therapeutic strategies such as mitochondrial transfer/transplantation, targeting microRNAs, using stem cells, photobiomodulation, diet, and exercise were also discussed in this review, which may provide valuable insights into clinical aspects. A better understanding of the roles of mitochondria in the pathophysiology of PD may provide a rationale for designing novel therapeutic interventions in our fight against PD.

The Pharmacological Activity of Garlic (Allium sativum) in Parkinson's Disease: From Molecular Mechanisms to the Therapeutic Potential

Parkinson's disease (PD), one of the most common neurological diseases worldwide, is mainly characterized neuropathologically by the dopaminergic neurodegeneration in the substantia nigra pars compacta of the brainstem. Genetic and environmental factors contribute to PD pathophysiology through modulation of pleiotropic cellular mechanisms. The currently available treatment options focus only on replenishing dopamine and do not alter disease progression. Interestingly, garlic (Allium sativum), globally famed for its flavor and taste-enhancing properties, has shown protective activity in different PD models. Numerous chemical constituents of garlic, mainly the organosulfur compounds, have been shown to exhibit anti-Parkinsonian effects by targeting oxidative stress, mitochondrial impairment, and neuroinflammation-related signaling. However, despite its therapeutic potential against PD, the major bioactive components of garlic display some stability issues and some adverse effects. In the present review, we explore the therapeutic potential of garlic and its major constituents in PD, the molecular mechanisms responsible for its pharmaceutical activity, and the associated limitations that need to be overcome for its future potential use in clinical practice.

Tat-GSTpi Inhibits Dopaminergic Cells against MPP+-Induced Cellular Damage via the Reduction of Oxidative Stress and MAPK Activation

Glutathione S-transferase pi (GSTpi) is a member of the GST family and plays many critical roles in cellular processes, including anti-oxidative and signal transduction. However, the role of anti-oxidant enzyme GSTpi against dopaminergic neuronal cell death has not been fully investigated. In the present study, we investigated the roles of cell permeable Tat-GSTpi fusion protein in a SH-SY5Y cell and a Parkinson’s disease (PD) mouse model. In the 1-methyl-4-phenylpyridinium (MPP+)-exposed cells, Tat-GSTpi protein decreased DNA damage and reactive oxygen species (ROS) generation. Furthermore, this fusion protein increased cell viability by regulating MAPKs, Bcl-2, and Bax signaling. In addition, Tat-GSTpi protein delivered into the substantia nigra (SN) of mice brains protected dopaminergic neuronal cell death in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD animal model. Our results indicate that the Tat-GSTpi protein inhibited cell death from MPP+- and MPTP-induced damage, suggesting that it plays a protective role during the loss of dopaminergic neurons in PD and that it could help to identify the mechanism responsible for neurodegenerative diseases, including PD.

Parkinson's disease and cardiovascular involvement: Edifying insights (Review)

Parkinson's disease (PD) is one of the most common neurodegenerative illnesses, and is a major healthcare burden with prodigious consequences on life-quality, morbidity, and survival. Cardiovascular diseases are the leading cause of mortality worldwide and growing evidence frequently reports their co-existence with PD. Cardiac dysautonomia due to autonomic nervous system malfunction is the most prevalent type of cardiovascular manifestation in these patients, comprising orthostatic and postprandial hypotension, along with supine and postural hypertension. Moreover, many studies have endorsed the risk of patients with PD to develop ischemic heart disease, heart failure and even arrhythmias, but the underlying mechanisms are not entirely clear. As importantly, the medication used in treating PD, such as levodopa, dopamine agonists or anticholinergic agents, is also responsible for cardiovascular adverse reactions, but further studies are required to elucidate the underlying mechanisms. The purpose of this review was to provide a comprehensive overview of current available data regarding the overlapping cardiovascular disease in patients with PD.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Free Radicals and Oxidative Stress: Signaling Mechanisms, Redox Basis for Human Diseases, and Cell Cycle Regulation

Free radicals contain one or more unpaired electrons in their valence shell, thus making them unstable, short-lived, and highly reactive species. Excessive generation of these free radicals ultimately leads to oxidative stress causing oxidation and damage to significant macromolecules in the living system and essentially disrupting signal transduction pathways and antioxidants equilibrium. At lower concentrations, ROS serves as "second messengers," influencing many physiological processes in the cell. However, higher concentrations beyond cell capacity cause oxidative stress, contributing to human pathologies such as diabetes, cancer, Parkinson's disease, cardiovascular diseases, cataract, asthma, hypertension, atherosclerosis, arthritis, and Alzheimer's disease. Signaling pathways such as NF-κB, MAPKs, PI3K/Akt/ mTOR, and Keap1-Nrf2- ARE modulate the detrimental effects of oxidative stress by increasing the expression of cellular antioxidant defenses, phase II detoxification enzymes, and decreased production of ROS. Free radicals such as H2O2 are indeed needed for the advancement of the cell cycle as these molecules influence DNA, proteins, and enzymes in the cell cycle pathway. In the course of cell cycle progression, the cellular redox environment becomes more oxidized, moving from the G1 phase, becoming higher in G2/M and moderate in the S phase. Signals in the form of an increase in cellular pro-oxidant levels are required, and these signals are often terminated by a rise in the amount of antioxidants and MnSOD with a decrease in the level of cyclin D1 proteins. Therefore, understanding the mechanism of cell cycle redox regulation will help in the therapy of many diseases.

Neuroprotective Potential and Underlying Pharmacological Mechanism of Carvacrol for Alzheimer's and Parkinson's Diseases

The phytochemicals have antioxidant properties to counter the deleterious effects of oxidative stress in the central nervous system and can be a promising drug candidate for neurodegenerative diseases. Among various phytochemicals, constituents of spice origin have recently received special attention for neurodegenerative diseases owing to their health benefits, therapeutic potential, edible nature, and dietary accessibility and availability. Carvacrol, a phenolic monoterpenoid, has garnered attention in treating and managing various human diseases. It possesses diverse pharmacological effects, including antioxidant, anti-inflammatory, antimicrobial and anticancer. Alzheimer's disease (AD) and Parkinson's disease (PD) are major public health concerns that place a significant financial burden on healthcare systems worldwide. The global burden of these diseases is expected to increase in the next few decades owing to increasing life expectancies. Currently, there is no cure for neurodegenerative diseases, such as AD and PD, and the available drugs only give symptomatic relief. For a long time, oxidative stress has been recognized as a primary contributor to neurodegeneration. Carvacrol enhances memory and cognition by modulating the effects of oxidative stress, inflammation, and Aβ25-35- induced neurotoxicity in AD. Moreover, it also reduces the production of reactive oxygen species and proinflammatory cytokine levels in PD, which further prevents the loss of dopaminergic neurons in the substantia nigra and improves motor functions. This review highlights carvacrol's potential antioxidant and anti-inflammatory properties in managing and treating AD and PD.

New Insights into the Gut Microbiota in Neurodegenerative Diseases from the Perspective of Redox Homeostasis

An imbalance between oxidants and antioxidants in the body can lead to oxidative stress, which is one of the major causes of neurodegenerative diseases. The gut microbiota contains trillions of beneficial bacteria that play an important role in maintaining redox homeostasis. In the last decade, the microbiota-gut-brain axis has emerged as a new field that has revolutionized the study of the pathology, diagnosis, and treatment of neurodegenerative diseases. Indeed, a growing number of studies have found that communication between the brain and the gut microbiota can be accomplished through the endocrine, immune, and nervous systems. Importantly, dysregulation of the gut microbiota has been strongly associated with the development of oxidative stress-mediated neurodegenerative diseases. Therefore, a deeper understanding of the relationship between the gut microbiota and redox homeostasis will help explain the pathogenesis of neurodegenerative diseases from a new perspective and provide a theoretical basis for proposing new therapeutic strategies for neurodegenerative diseases. In this review, we will describe the role of oxidative stress and the gut microbiota in neurodegenerative diseases and the underlying mechanisms by which the gut microbiota affects redox homeostasis in the brain, leading to neurodegenerative diseases. In addition, we will discuss the potential applications of maintaining redox homeostasis by modulating the gut microbiota to treat neurodegenerative diseases, which could open the door for new therapeutic approaches to combat neurodegenerative diseases.

Investigating key factors underlying neurodegeneration linked to alpha-synuclein spread

AIMS

It has long been considered that accumulation of pathological alpha-synuclein (aSyn) leads to synaptic/neuronal loss which then results in behavioural and cognitive dysfunction. To investigate this claim, we investigated effects downstream of aSyn preformed fibrils (PFFs) and 6-hydroxydopamine (6-OHDA), because aSyn PFFs induce spreading/accumulation of aSyn, and 6-OHDA rapidly causes local neuronal loss.

METHODS

We injected mouse aSyn PFFs into the medial forebrain bundle (MFB) of Sprague-Dawley rats. We investigated spread of pathological aSyn, phosphorylation of aSyn and tau, oxidative stress, synaptic/neuronal loss and cognitive dysfunction 60, 90 and 120 days after injection. Similarly, we injected 6-OHDA into the MFB and examined the same parameters 1 and 3 weeks after injection.

RESULTS

Following aSyn PFF injection, phosphorylated aSyn was found distant from the injection site in the hippocampus and frontal cortex. However, despite neuron loss being evident close to the site of injection in the substantia nigra at 120 days post injection, there were no other neurodegeneration-associated features associated with aSyn including synaptic loss. In contrast, 6-OHDA caused severe neuronal loss in the substantia nigra at 3 weeks post injection that was accompanied by phosphorylation of aSyn and tau, oxidative stress, loss of synaptic proteins, cognitive and motor dysfunction.

CONCLUSIONS

Our results demonstrate that spread/replication and slow accumulation of pathological aSyn may not be sufficient to induce neurodegenerative changes. In contrast, oxidative stress responses in addition to aSyn accumulation were associated with other Parkinson's disease (PD)-associated abnormalities and cognitive dysfunction. Our results may be important when considering why only some PD patients develop dementia.

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

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

Synthesis and antioxidant activity of 3-(2-R-ylidenehydrazinyl)-6-tert-butyl-4H-[1,2,4]triazin-5-ones

Synthesis and structure elucidation of several series of new hydrazones containing 1,2,4-triazine-5-one core and their antioxidant activity are presented. The target compounds have been synthesized via interaction of either 4-amino-6-(tert-butyl)-3-hydrazinyl-1,2,4-triazin-5(4H)-one or 6-(tert-butyl)-3-hydrazinyl-1,2,4-triazin-5(2H)-one with a wide range of compounds with a carbonyl group in moderate to high yields. Molecular structures of the synthesized compounds were confirmed by 1H NMR, 13C NMR, and elemental analyses. The antioxidant activity of these compounds against ascorbic acid was screened to determine their potential as promising oxidative stress suppressors. Our data showed that hydrazones derived from 4-amino-6-(tert-butyl)-3-hydrazinyl-1,2,4-triazin-5(4H)-one are the most active antioxidants among all tested compounds. Furthermore, 3 compounds of this series have been proved to be twice as active as ascorbic acid does. The conclusions are substantiated for in-depth investigations of these derivatives as promising agents for the treatment of disorders accompanied by oxidative stress.

Neuroprotective Properties of Bis-Sulfonamide Derivatives Against 6-OHDA-Induced Parkinson's Model via Sirtuin 1 Activity and in silico Pharmacokinetic Properties

Parkinson's disease (PD) is considered one of the health problems in the aging society. Due to the limitations of currently available drugs in preventing disease progression, the discovery of novel neuroprotective agents has been challenged. Sulfonamide and its derivatives were reported for several biological activities. Herein, a series of 17 bis-sulfonamide derivatives were initially tested for their neuroprotective potential and cytotoxicity against the 6-hydroxydopamine (6-OHDA)-induced neuronal death in SH-SY5Y cells. Subsequently, six compounds (i.e., 2, 4, 11, 14, 15, and 17) were selected for investigations on underlying mechanisms. The data demonstrated that the pretreatment of selected compounds (5 μM) can significantly restore the level of cell viability, protect against mitochondrial membrane dysfunction, decrease the activity of lactate dehydrogenase (LDH), decrease the intracellular oxidative stress, and enhance the activity of NAD-dependent deacetylase sirtuin-1 (SIRT1). Molecular docking was also performed to support that these compounds could act as SIRT1 activators. In addition, in silico pharmacokinetic and toxicity profile prediction was also conducted for guiding the potential development. Thus, the six neuroprotective bis-sulfonamides were highlighted as potential agents to be further developed for PD management.

The Protein-Rich Fraction from Spirulina platensis Exerts Neuroprotection in Hemiparkinsonian Rats by Decreasing Brain Inflammatory-Related Enzymes and Glial Fibrillary Acidic Protein Expressions

Spirulina platensis is a cyanobacterium with high protein content and presenting neuroprotective effects. Now, we studied a protein-enriched fraction (SPF), on behavior, neurochemical and immunohistochemical (IHC) assays in hemiparkinsonian rats, distributed into the groups: SO (sham-operated), 6-hydroxydopamine (6-OHDA), and 6-OHDA (treated with SPF, 5 and 10 mg/kg, p.o., 15 days). Afterward, animals were subjected to behavioral tests and euthanized, and brain areas used for neurochemical and IHC assays. SPF partly reversed the changes in the apomorphine-induced rotations, open field and forced swim tests, and also the decrease in striatal dopamine and 3,4-dihydroxyphenylacetic acid contents seen in hemiparkinsonian rats. Furthermore, SPF reduced brain oxidative stress and increased striatal expressions of tyrosine hydroxylase and dopamine transporter and significantly reduced hippocampal inducible nitric oxide synthase, cyclooxygenase-2 and glial fibrillary acidic protein expressions. The data suggest that the protein fraction from S. platensis, through its brain anti-inflammatory and antioxidative actions, exerts neuroprotective effects that could benefit patients affected by neurodegenerative diseases, like Parkinson's disease.

Novel inflammasome and oxidative modulators in Parkinson's disease: A prospective study

INTRODUCTION

The etiopathogenesis of Parkinson's disease (PD) is not clear. Yet, it seems likely that inflammation as well as oxidative stress plays a major role in the disease pathogenesis. Based on our previous findings, we aimed to investigate prospective changes in peripheral inflammasome and oxidative modulators in relation to the progression of motor symptoms and severity of PD.

METHODS

Levels of inflammatory and oxidative markers in the serum of PD patients and healthy controls were estimated by quantitative ELISA and spectrophotometric methods at the baseline and at the end of one year.

RESULTS

In PD patients, serum NLRP3 inflammasome and IL-1β levels increased significantly over a year, compared to the baseline. The average enzymatic activity of serum SOD1 was also augmented at one-year follow-up. Alongside these serummarker changes, the mean motorseverity of this patient cohort worsened over the time period.

CONCLUSION

This pioneering study identified a novel association of peripheral inflammatory and oxidative markers with the progression of PD. Correlation of these serum proteins with the central pathological changes in PD and disease severity in a prospective manner might be useful not only for prognostication, but for understanding disease mechanisms and for planning future therapeutic strategies.

Gut Microbiota: A Novel Therapeutic Target for Parkinson’s Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease characterized by motor dysfunction. Growing evidence has demonstrated that gut dysbiosis is involved in the occurrence, development and progression of PD. Numerous clinical trials have identified the characteristics of the changed gut microbiota profiles, and preclinical studies in PD animal models have indicated that gut dysbiosis can influence the progression and onset of PD via increasing intestinal permeability, aggravating neuroinflammation, aggregating abnormal levels of α-synuclein fibrils, increasing oxidative stress, and decreasing neurotransmitter production. The gut microbiota can be considered promising diagnostic and therapeutic targets for PD, which can be regulated by probiotics, psychobiotics, prebiotics, synbiotics, postbiotics, fecal microbiota transplantation, diet modifications, and Chinese medicine. This review summarizes the recent studies in PD-associated gut microbiota profiles and functions, the potential roles, and mechanisms of gut microbiota in PD, and gut microbiota-targeted interventions for PD. Deciphering the underlying roles and mechanisms of the PD-associated gut microbiota will help interpret the pathogenesis of PD from new perspectives and elucidate novel therapeutic strategies for PD.

Evidence for Oxidative Pathways in the Pathogenesis of PD: Are Antioxidants Candidate Drugs to Ameliorate Disease Progression?

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that arises due to a complex and variable interplay between elements including age, genetic, and environmental risk factors that manifest as the loss of dopaminergic neurons. Contemporary treatments for PD do not prevent or reverse the extent of neurodegeneration that is characteristic of this disorder and accordingly, there is a strong need to develop new approaches which address the underlying disease process and provide benefit to patients with this debilitating disorder. Mitochondrial dysfunction, oxidative damage, and inflammation have been implicated as pathophysiological mechanisms underlying the selective loss of dopaminergic neurons seen in PD. However, results of studies aiming to inhibit these pathways have shown variable success, and outcomes from large-scale clinical trials are not available or report varying success for the interventions studied. Overall, the available data suggest that further development and testing of novel therapies are required to identify new potential therapies for combating PD. Herein, this review reports on the most recent development of antioxidant and anti-inflammatory approaches that have shown positive benefit in cell and animal models of disease with a focus on supplementation with natural product therapies and selected synthetic drugs.

The role of nutrition on Parkinson's disease: a systematic review

BACKGROUND

Parkinson's disease (PD) in elderly patients is the second most prevalent neurodegenerative disease. The pathogenesis of PD is associated with dopaminergic neuron degeneration of the substantia nigra in the basal ganglia, causing classic motor symptoms. Oxidative stress, mitochondrial dysfunction, and neuroinflammation have been identified as possible pathways in laboratory investigations. Nutrition, a potentially versatile factor from all environmental factors affecting PD, has received intense research scrutiny.

METHODS

A systematic search was conducted in the MEDLINE, EMBASE, and WEB OF SCIENCE databases from 2000 until the present. Only randomized clinical trials (RCTs), observational case-control studies, and follow-up studies were included.

RESULTS

We retrieved fifty-two studies that met the inclusion criteria. Most selected studies investigated the effects of malnutrition and the Mediterranean diet (MeDiet) on PD incidence and progression. Other investigations contributed evidence on the critical role of microbiota, vitamins, polyphenols, dairy products, coffee, and alcohol intake.

CONCLUSIONS

There are still many concerns regarding the association between PD and nutrition, possibly due to underlying genetic and environmental factors. However, there is a body of evidence revealing that correcting malnutrition, gut microbiota, and following the MeDiet reduced the onset of PD and reduced clinical progression. Other factors, such as polyphenols, polyunsaturated fatty acids, and coffee intake, can have a potential protective effect. Conversely, milk and its accessory products can increase PD risk. Nutritional intervention is essential for neurologists to improve clinical outcomes and reduce the disease progression of PD.

N-cystaminylbiguanide MC001 prevents neuron cell death and alleviates motor deficits in the MPTP-model of Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra (SN), which is highly associated with oxidative stress. Antioxidants are therefore considered as potential therapies in PD treatment. In this study, we examined the neuroprotective effect of a cysteamine-based biguanide N-cystaminylbiguanide (MC001) in the MPTP mouse model of PD. The results showed that MC001 prevented neuron cell death and alleviated motor deficits in the MPTP mouse model of PD. Both in vitro and in vivo data indicated that MC001 may exert its neuroprotective effect by alleviating ROS production, suppressing neuroinflammation, and upregulating BDNF expression. Further mechanistic studies revealed that MC001 promoted GSH synthesis by inducing the expression of Glutamate-cysteine ligase catalytic subunit (Gclc) and enhancing the activity of Glutamate-cysteine ligase (Gcl). Our results suggest that MC001 warrants further investigation as a potential candidate for the treatment of PD.

Uric Acid Enhances Neurogenesis in a Parkinsonian Model by Remodeling Mitochondria

Background

Adult neurogenesis is the process of generating new neurons to enter neural circuits and differentiate into functional neurons. However, it is significantly reduced in Parkinson’s disease (PD). Uric acid (UA), a natural antioxidant, has neuroprotective properties in patients with PD. This study aimed to investigate whether UA would enhance neurogenesis in PD.

Methods

We evaluated whether elevating serum UA levels in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonian mouse model would restore neurogenesis in the subventricular zone (SVZ). For a cellular model, we primary cultured neural precursor cells (NPCs) from post-natal day 1 rat and evaluated whether UA treatment promoted cell proliferation against 1-methyl-4-phenylpyridinium (MPP⁺).

Results

Uric acid enhanced neurogenesis in both in vivo and in vitro parkinsonian model. UA-elevating therapy significantly increased the number of bromodeoxyuridine (BrdU)-positive cells in the SVZ of PD animals as compared to PD mice with normal UA levels. In a cellular model, UA treatment increased the expression of Ki-67. In the process of modulating neurogenesis, UA elevation up-regulated the expression of mitochondrial fusion markers.

Conclusion

In MPTP-induced parkinsonian model, UA probably enhanced neurogenesis via regulating mitochondrial dynamics, promoting fusion machinery, and inhibiting fission process.