Oxidative stress and mitochondrial dysfunction are the underlying events of dopaminergic neurodegeneration in homocysteine rat model of Parkinson's disease

Nicotinamide N-Methyltransferase (NNMT): A New Hope for Treating Aging and Age-Related Conditions

The complex process of aging leads to a gradual deterioration in the function of cells, tissues, and the entire organism, thereby increasing the risk of disease and death. Nicotinamide N-methyltransferase (NNMT) has attracted attention as a potential target for combating aging and its related pathologies. Studies have shown that NNMT activity increases over time, which is closely associated with the onset and progression of age-related diseases. NNMT uses S-adenosylmethionine (SAM) as a methyl donor to facilitate the methylation of nicotinamide (NAM), converting NAM into S-adenosyl-L-homocysteine (SAH) and methylnicotinamide (MNA). This enzymatic action depletes NAM, a precursor of nicotinamide adenine dinucleotide (NAD+), and generates SAH, a precursor of homocysteine (Hcy). The reduction in the NAD+ levels and the increase in the Hcy levels are considered important factors in the aging process and age-related diseases. The efficacy of RNA interference (RNAi) therapies and small-molecule inhibitors targeting NNMT demonstrates the potential of NNMT as a therapeutic target. Despite these advances, the exact mechanisms by which NNMT influences aging and age-related diseases remain unclear, and there is a lack of clinical trials involving NNMT inhibitors and RNAi drugs. Therefore, more in-depth research is needed to elucidate the precise functions of NNMT in aging and promote the development of targeted pharmaceutical interventions. This paper aims to explore the specific role of NNMT in aging, and to evaluate its potential as a therapeutic target.

Homocysteine-induced sustained GluN2A NMDA receptor stimulation leads to mitochondrial ROS generation and neurotoxicity

Homocysteine, a sulfur-containing amino acid derived from methionine metabolism, is a known agonist of N-methyl-D-aspartate receptor (NMDAR) and is involved in neurotoxicity. Our previous findings showed that neuronal exposure to elevated homocysteine levels leads to sustained low-level increase in intracellular Ca2+, which is dependent on GluN2A subunit-containing NMDAR (GluN2A-NMDAR) stimulation. These studies further showed a role of ERK MAPK in homocysteine-GluN2A-NMDAR-mediated neuronal death. However, the intracellular mechanisms associated with such sustained GluN2A-NMDAR stimulation and subsequent Ca2+ influx have remained unexplored. Using live-cell imaging with Fluo3-AM and biochemical approaches, we show that homocysteine-GluN2A NMDAR-induced initial Ca2+ influx triggers sequential phosphorylation and subsequent activation of the proline rich tyrosine kinase 2 (Pyk2) and Src family kinases, which in turn phosphorylates GluN2A-Tyr1325 residue of GluN2A-NMDARs to maintain channel activity. The continuity of this cycle of events leads to sustained Ca2+ influx through GluN2A-NMDAR. Our findings also show that lack of activation of the regulatory tyrosine phosphatase STEP, which can limit Pyk2 and Src family kinase activity further contributes to the maintenance of this cycle. Additional studies using live-cell imaging of neurons expressing a redox-sensitive GFP targeted to the mitochondrial matrix show that treatment with homocysteine leads to a progressive increase in mitochondrial reactive oxygen species generation, which is dependent on GluN2A-NMDAR-mediated sustained ERK MAPK activation. This later finding demonstrates a novel role of GluN2A-NMDAR in homocysteine-induced mitochondrial ROS generation and highlights the role of ERK MAPK as the intermediary signaling pathway between GluN2A-NMDAR stimulation and mitochondrial reactive oxygen species generation.

Homocysteine and Parkinson's disease

Homocysteine (Hcy) is an important metabolite in methionine metabolism. When the metabolic pathway of homocysteine is abnormal, it will accumulate in the body and eventually lead to hyperhomocysteinemia. In recent years, many studies have found that hyperhomocysteinemia is related to the occurrence and development of Parkinson's disease. This study reviews the roles of homocysteine in the pathogenesis of Parkinson's disease and illustrates the harmful effects of hyperhomocysteinemia on Parkinson's disease.

The association between homocysteine and bacterial vaginosis: results from NHANES 2001-2004

Although no study has directly shown the relationship between bacterial vaginosis (BV) and homocysteine (HCY), we still found some association between these two through extensive literature and data analysis. BV score was calculated by Nugent's method, less than equal to 6 is negative and greater than equal to 7 is positive. This article describes interrelationships we mined from data extracted by NHANES regarding BV and HCY under multiple covariates. We used two cycles of NHANES 2001-2002 and 2003-2004 in our study. We included 2398 participants in our study who recently completed the interview and the MEC tests. By investigating the relationship between BV and HCY under multivariate conditions, multiple linear regression analysis was performed. These factors may have influenced the results, such as ethnicity, age, education level, body mass index (BMI), etc. Serum vitamin B12, ferritin, percentage of segmented centrioles, and number of segmented centrioles were selected as potential covariates in our study. We observed that both the coarse model and the two adjusted models showed a high correlation between HCY and BV, and the correlation was positive. In the coarse model, OR = 1.26, 95% confidence interval (CI) 1.10, 1.44, P = 0.0018); HCY was positively correlated with BV (OR = 1.19, 95% confidence interval (CI) 1.05, 1.34, P = 0.0121). Multiple linear regression analysis was used to investigate the connection between BV and HCY under multivariate settings. The results of this study indicate that HCY is positively associated with the prevalence of BV and may play an important role in the prevention and management of BV.

Therapeutic considerations of bioactive compounds in Alzheimer's disease and Parkinson's disease: Dissecting the molecular pathways

Leading neurodegenerative diseases Alzheimer's disease (AD) and Parkinson's disease (PD) are characterized by the impairment of memory and motor functions, respectively. Despite several breakthroughs, there exists a lack of disease-modifying treatment strategies for these diseases, as the available drugs provide symptomatic relief and bring along side effects. Bioactive compounds are reported to bear neuroprotective properties with minimal toxicity, however, a detailed elucidation of their modes of neuroprotection is lacking. The review elucidates the neuroprotective mechanism(s) of some of the major phyto-compounds in pre-clinical and clinical studies of AD and PD to understand their potential in combating these diseases. Curcumin, eugenol, resveratrol, baicalein, sesamol and so on have proved efficient in countering the pathological hallmarks of AD and PD. Curcumin, resveratrol, caffeine and so on have reached the clinical phases of these diseases, while aromadendrin, delphinidin, cyanidin and xanthohumol are yet to be extensively explored in pre-clinical phases. The review highlights the need for extensive investigation of these compounds in the clinical stages of these diseases so as to utilize their disease-modifying abilities in the real field of treatment. Moreover, poor pharmacokinetic properties of natural compounds are constraints to their therapeutic yields and this review suggests a plausible contribution of nanotechnology in overcoming these limitations.

The Development and Full Validation of a Novel Liquid Chromatography Electrochemical Detection Method for Simultaneous Determination of Nine Catecholamines in Rat Brain

Objectives

Chemical neurotransmission, managed by neurotransmitters, has a crucial role in brain processes such as fear, memory, learning, and pain, or neuropathology such as schizophrenia, epilepsy, anxiety/depression, and Parkinson's disease. The measurement of these compounds is used to elucidate the disease mechanisms and evaluate the outcomes of therapeutic interventions. However, this can be quite difficult because of various matrix effects and the problems of chromatographic separation of analysts. In the current study; for the first time, an optimized and fully validated high-performance liquid chromatography-electrochemical detection (HPLC-EC) method according to Food and Drug Administration and European Medicines Agency Bioanalytical Validation Guidance was developed for the simultaneous analysis of nine neurotransmitter compounds, namely dopamine, homovanilic acid, vanilmandelic acid, serotonin (SER), 5-hydroxyindole-3-acetic acid, 4-hydroxy-3-methoxyphenylglycol, norepinephrine, 3,4 dihydroxyphenylacetic acid, and 3-methoxytyramine and simultaneously determined in rat brain samples.

Materials and Methods

Separation was achieved with 150 mm x 4.6 mm, 2.6 μm Kinetex F5 (Phenomenex, USA) column isocratically, and analysis was carried out by HPLC equipped with a DECADE II EC detector.

Results

The method exhibited good selectivity, and the correlation coefficient values for each analyte's calibration curves were > 0.99. The detection and quantification limits ranged from 0.01 to 0.03 ng/mL and 3.04 to 9.13 ng/mL, respectively. The stability of the analyses and method robustness were also examined in detail in the study, and the obtained results are presented statistically.

Conclusion

The developed and fully validated method has been successfully applied to actual rat brain samples, and important results have been obtained. In the rat brain sample analysis, the lowest number of SER and the highest amount of noradrenaline were found.

Association between the risk and severity of Parkinson's disease and plasma homocysteine, vitamin B12 and folate levels: a systematic review and meta-analysis

Background

Parkinson's disease (PD) is recognized as the second most prevalent progressive neurodegenerative disease among the elderly. However, the relationship between PD and plasma homocysteine (Hcy), vitamin B12, and folate has yielded inconsistent results in previous studies. Hence, in order to address this ambiguity, we conducted a meta-analysis to summarize the existing evidence.

Methods

Suitable studies published prior to May 2023 were identified by searching PubMed, EMBASE, Medline, Ovid, and Web of Science. The methodological quality of eligible studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). Meta-analysis and publication bias were then performed using R version 4.3.1.

Results

The results of our meta-analysis, consisting of case-control and cross-sectional studies, showed that PD patients had lower folate and vitamin B12 levels (SMD [95%CI]: -0.30[-0.39, -0.22], p < 0.001 for Vitamin B12; SMD [95%CI]: -0.20 [-0.28, -0.13], p < 0.001 for folate), but a significant higher Hcy level (SMD [95%CI]: 0.86 [0.59, 1.14], p < 0.001) than healthy people. Meanwhile, PD was significantly related to hyperhomocysteinemia (SMD [95%]: 2.02 [1.26, 2.78], p < 0.001) rather than plasma Hcy below 15 μmol/L (SMD [95%]: -0.31 [-0.62, 0.00], p = 0.05). Subgroup analysis revealed associations between the Hcy level of PD patients and region (p = 0.03), age (p = 0.03), levodopa therapy (p = 0.03), Hoehn and Yahr stage (p < 0.001), and cognitive impairment (p < 0.001). However, gender (p = 0.38) and sample size (p = 0.49) were not associated.

Conclusion

Hcy, vitamin B12, and folic acid potentially predict the onset and development of PD. Additionally, multiple factors were linked to Hcy levels in PD patients. Further studies are needed to comprehend their roles in PD.

Homocysteine May Decrease Glucose Uptake and Alter the Akt/GSK3β/GLUT1 Signaling Pathway in Hippocampal Slices: Neuroprotective Effects of Rivastigmine and Ibuprofen

Homocysteine (Hcy) is a risk factor for neurodegenerative diseases, such as Alzheimer's Disease, and is related to cellular and tissue damage. In the present study, we verified the effect of Hcy on neurochemical parameters (redox homeostasis, neuronal excitability, glucose, and lactate levels) and the Serine/Threonine kinase B (Akt), Glucose synthase kinase-3β (GSK3β) and Glucose transporter 1 (GLUT1) signaling pathway in hippocampal slices, as well as the neuroprotective effects of ibuprofen and rivastigmine alone or in combination in such effects. Male Wistar rats (90 days old) were euthanized and the brains were dissected. The hippocampus slices were pre-treated for 30 min [saline medium or Hcy (30 µM)], then the other treatments were added to the medium for another 30 min [ibuprofen, rivastigmine, or ibuprofen + rivastigmine]. The dichlorofluorescein formed, nitrite and Na+, K+-ATPase activity was increased by Hcy at 30 µM. Ibuprofen reduced dichlorofluorescein formation and attenuated the effect of Hcy. The reduced glutathione content was reduced by Hcy. Treatments with ibuprofen and Hcy + ibuprofen increased reduced glutathione. Hcy at 30 µM caused a decrease in hippocampal glucose uptake and GLUT1 expression, and an increase in Glial Fibrillary Acidic Protein-protein expression. Phosphorylated GSK3β and Akt levels were reduced by Hcy (30 µM) and co-treatment with Hcy + rivastigmine + ibuprofen reversed these effects. Hcy toxicity on glucose metabolism can promote neurological damage. The combination of treatment with rivastigmine + ibuprofen attenuated such effects, probably by regulating the Akt/GSK3β/GLUT1 signaling pathway. Reversal of Hcy cellular damage by these compounds may be a potential neuroprotective strategy for brain damage.

Combating Dopaminergic Neurodegeneration in Parkinson's Disease through Nanovesicle Technology

Parkinson's disease (PD) is characterized by dopaminergic neurodegeneration, resulting in dopamine depletion and motor behavior deficits. Since the discovery of L-DOPA, it has been the most prescribed drug for symptomatic relief in PD, whose prolonged use, however, causes undesirable motor fluctuations like dyskinesia and dystonia. Further, therapeutics targeting the pathological hallmarks of PD including α-synuclein aggregation, oxidative stress, neuroinflammation, and autophagy impairment have also been developed, yet PD treatment is a largely unmet success. The inception of the nanovesicle-based drug delivery approach over the past few decades brings add-on advantages to the therapeutic strategies for PD treatment in which nanovesicles (basically phospholipid-containing artificial structures) are used to load and deliver drugs to the target site of the body. The present review narrates the characteristic features of nanovesicles including their blood-brain barrier permeability and ability to reach dopaminergic neurons of the brain and finally discusses the current status of this technology in the treatment of PD. From the review, it becomes evident that with the assistance of nanovesicle technology, the therapeutic efficacy of anti-PD pharmaceuticals, phyto-compounds, as well as that of nucleic acids targeting α-synuclein aggregation gained a significant increment. Furthermore, owing to the multiple drug-carrying abilities of nanovesicles, combination therapy targeting multiple pathogenic events of PD has also found success in preclinical studies and will plausibly lead to effective treatment strategies in the near future.

A one-step aptasensor for ultrasensitive detection of lung cancer marker homocysteine based on multifunctional carbon nanotubes by square-wave voltammetry

In this work, a one-step aptasensor for ultrasensitive detection of homocysteine (HCY) is developed based on multifunctional carbon nanotubes, which is magnetic multi-walled carbon nanotubes (Fe₃O₄@MWCNTs) combined with the aptamer (Apt) for HCY (Fe₃O₄@MWCNTs-Apt). Fe₃O₄@MWCNTs-Apt have multiple functions as follows. (1) Apt immobilized could selectively capture all target molecules HCY in the sample; (2) Magnetic Fe₃O₄ nanoparticles could separate all target molecules HCY captured by Apt from the sample substrate to eliminate the background interference and achieve one-step preparation of the aptasensor; And (3), MWCNTs with good electrical conductivity become a new electrode surface, construct a three-dimensional electrode surface network, make the electron transfer easier and thus then enhance the signal response. Results show that there is a good linear relationship between peak current of square-wave voltammetry (SWV) and HCY concentration in the range of 0.01 μmol/L-1 μmol/L, with a limit of detection (LOD) 0.002 μmol/L. And, selectivity, reproducibility, precision and accuracy are all satisfactory. In addition, it could be applied to the detection of HCY in the plasma of lung cancer patients successfully, suggesting that this one-step aptasensor for HCY has a potential in practical clinical applications.

Mitochondrial dysfunction-targeting therapeutics of natural products in Parkinson's disease

Parkinson's disease (PD), the second most common neurodegenerative disease worldwide, often occurs in middle-aged and elderly individuals. The pathogenesis of PD is complex and includes mitochondrial dysfunction, and oxidative stress. Recently, natural products with multiple structures and their bioactive components have become one of the most important resources for small molecule PD drug research targeting mitochondrial dysfunction. Multiple lines of studies have proven that natural products display ameliorative benefits in PD treatment by regulating mitochondrial dysfunction. Therefore, a comprehensive search of recent published articles between 2012 and 2022 in PubMed, Web of Science, Elesvier, Wliey and Springer was carried out, focusing on original publications related to natural products against PD by restoring mitochondrial dysfunction. This paper presented the mechanisms of various kinds of natural products on PD-related mitochondrial dysfunction regulation and provided evidence that natural products are promising to be developed as drugs for PD therapeutics.

Parkinson's Disease Risk and Hyperhomocysteinemia: The Possible Link

Parkinson's disease (PD) is one of the most common degenerative brain disorders caused by the loss of dopaminergic neurons in the substantia nigra (SN). Lewy bodies and -synuclein accumulation in the SN are hallmarks of the neuropathology of PD. Due to lifestyle changes and prolonged L-dopa administration, patients with PD frequently have vitamin deficiencies, especially folate, vitamin B6, and vitamin B12. These disorders augment circulating levels of Homocysteine with the development of hyperhomocysteinemia, which may contribute to the pathogenesis of PD. Therefore, this review aimed to ascertain if hyperhomocysteinemia may play a part in oxidative and inflammatory signaling pathways that contribute to PD development. Hyperhomocysteinemia is implicated in the pathogenesis of neurodegenerative disorders, including PD. Hyperhomocysteinemia triggers the development and progression of PD by different mechanisms, including oxidative stress, mitochondrial dysfunction, apoptosis, and endothelial dysfunction. Particularly, the progression of PD is linked with high inflammatory changes and systemic inflammatory disorders. Hyperhomocysteinemia induces immune activation and oxidative stress. In turn, activated immune response promotes the development and progression of hyperhomocysteinemia. Therefore, hyperhomocysteinemia-induced immunoinflammatory disorders and abnormal immune response may aggravate abnormal immunoinflammatory in PD, leading to more progression of PD severity. Also, inflammatory signaling pathways like nuclear factor kappa B (NF-κB) and nod-like receptor pyrin 3 (NLRP3) inflammasome and other signaling pathways are intricate in the pathogenesis of PD. In conclusion, hyperhomocysteinemia is involved in the development and progression of PD neuropathology either directly via induction degeneration of dopaminergic neurons or indirectly via activation of inflammatory signaling pathways.

Advances of H2S in Regulating Neurodegenerative Diseases by Preserving Mitochondria Function

Neurotoxicity is induced by different toxic substances, including environmental chemicals, drugs, and pathogenic toxins, resulting in oxidative damage and neurodegeneration in mammals. The nervous system is extremely vulnerable to oxidative stress because of its high oxygen demand. Mitochondria are the main source of ATP production in the brain neuron, and oxidative stress-caused mitochondrial dysfunction is implicated in neurodegenerative diseases. H2S was initially identified as a toxic gas; however, more recently, it has been recognized as a neuromodulator as well as a neuroprotectant. Specifically, it modulates mitochondrial activity, and H2S oxidation in mitochondria produces various reactive sulfur species, thus modifying proteins through sulfhydration. This review focused on highlighting the neuron modulation role of H2S in regulating neurodegenerative diseases through anti-oxidative, anti-inflammatory, anti-apoptotic and S-sulfhydration, and emphasized the importance of H2S as a therapeutic molecule for neurological diseases.

Association of serum homocysteine levels with intestinal flora and cognitive function in schizophrenia

Some studies have indicated that elevated homocysteine (Hcy) levels and intestinal flora may be involved in schizophrenia (SZ) cognition pathophysiology. This study was the first to investigate the association among Hcy, intestinal flora and schizophrenia cognition. Here, 140 individuals were divided into two groups: SZ patients (N = 68) and healthy controls (HCs, N = 72). Participant data on serum Hcy levels, intestinal flora and cognitive function evaluation using the MATRICS Consensus Cognitive Battery (MCCB) were collected. Clinical symptoms of patients were evaluated using the Positive and Negative Syndrome Scale. Serum Hcy levels and the incidence of hyperhomocysteinaemia were considerably increased in SZ patients compared with HCs. Hcy levels were significantly negatively associated with verbal learning index scores (r = -0.425, p < 0.001) but positively associated with Eubacterium (r = 0.32, p = 0.007), Lactobacillus (r = 0.32, p = 0.008), Corynebacterium (r = 0.26, p = 0.035), Mogibacterium (r = 0.31, p = 0.01), and Bulleidia (r = 0.31, p = 0.01) in SZ patients. Our findings suggest that serum Hcy levels are associated with cognitive function and intestinal flora in SZ patients. However, the mechanism of the interaction between Hcy and intestinal flora and its effects on cognitive function in SZ patients requires further investigation.

Traversing through the cell signaling pathways of neuroprotection by betanin: therapeutic relevance to Alzheimer's Disease and Parkinson's Disease

Modulation of cell signaling pathways is the key area of research towards the treatment of neurodegenerative disorders. Altered Nrf2-Keap1-ARE (Nuclear factor erythroid-2-related factor 2-Kelch-like ECH-associated protein 1-Antioxidant responsive element) and SIRT1 (Sirtuin 1) cell signaling pathways are considered to play major role in the etiology and pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD). Strikingly, betanin, a betanidin 5-O-β-D-glucoside compound is reported to show commendable anti-oxidative, anti-inflammatory and anti-apoptotic effects in several disease studies including AD and PD. The present review discusses the pre-clinical studies demonstrating the neuroprotective effects of betanin by virtue of its potential to ameliorate oxidative stress, neuroinflammation, abnormal protein aggregation and cell death. It highlights the direct linkage between the neuroprotective abilities of betanin and upregulation of the Nrf2-Keap1-ARE and SIRT1 signaling pathways. The review further hypothesizes the involvement of the betanin-Nrf2-ARE route in the inhibition of beta-amyloid aggregation through beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), one of the pivotal hallmarks of AD. The present review hereby for the first time elaborately discusses the reported neuroprotective abilities of betanin and decodes the Nrf2 and SIRT1 modulating potential of betanin as a primary mechanism of action behind, hence highlighting it as a novel drug candidate for the treatment of neurodegenerative diseases in the near future.

Increased serum homocysteine in first episode and drug-naïve individuals with schizophrenia: sex differences and correlations with clinical symptoms

BACKGROUND

Accumulating evidence shows that homocysteine (Hcy) is implicated in the pathophysiology of schizophrenia, and plays an important role in clinical characteristics. This study evaluated the relationships between Hcy levels and clinical features in first-episode, Chinese Han, drug-naïve (FEDN) patients with schizophrenia.

METHODS

FEDN individuals (119 with schizophrenia and 81 healthy controls matched for age, sex, education, and body mass index (BMI)) were enrolled. The serum Hcy levels were determined by enzyme cycle assay experiments. Severities of clinical symptoms were rated on the Positive and Negative Syndrome Scale (PANSS).

RESULTS

FEDN individuals with schizophrenia had higher Hcy levels compared with healthy controls (F = 46.865, P < 0.001). Correlation analysis and multiple stepwise regression analyses showed that serum Hcy levels in FEDN schizophrenia individuals were positively correlated with PANSS general psychopathology subscale (r = 0.294, P = 0.001) and PANSS total score (r = 0.273, P = 0.003). No significant association was found between Hcy and age, BMI, PANSS positive subscale, and the PANSS negative subscale (all, P > 0.05). Male individuals had significantly higher serum Hcy levels than female individuals (F = 7.717, P = 0.006) after controlling for confounding factors (F = 0.759, P = 0.011).

CONCLUSIONS

Serum Hcy levels were increased in FEDN individuals with schizophrenia, and Hcy levels may be involved in pathophysiological mechanisms. Sex differences in Hcy levels were observed, with higher levels in male FEDN individuals compared to females.

Neuroprotective effect of phospholipase A2 from Malaysian Naja sumatrana venom against H2O2-induced cell damage and apoptosis

Oxidative stress is one of the factors involved in the pathogenesis of several neurodegenerative diseases. It has been reported that a secretory phospholipase A2 known as A2-EPTX-NSm1a has lower cytotoxicity in neuronal cells compared to its crude Naja sumatrana venom. In this study, A2-EPTX-NSm1a was tested for its neuroprotective activity on human neuroblastoma cells (SH-SY5Y) differentiated into cholinergic neurons against oxidative stress induced by hydrogen peroxide (H2O2). H2O2 treatment alone increased the caspase-3 and caspase-8 activities, whereas pre-treatment with A2-EPTX-NSm1a reduced the activity of these apoptosis-associated proteins. Moreover, A2-EPTX-NSm1a protects the morphology and ultrastructure of differentiated SH-SY5Y cells in the presence of H2O2. Oxidative stress increased the number of small mitochondria. Further evaluation showed the size of mitochondria with a length below 0.25 µm in oxidative stress conditions is higher than the control group, suggesting mitochondria fragmentation. Pre-treatment with A2-EPTX-NSm1a attenuated the number of mitochondria in cells with H2O2 Furthermore, A2-EPTX-NSm1a altered the expression of several neuroprotein biomarkers of GDNF, IL-8, MCP-1, TIMP-1, and TNF-R1 in cells under oxidative stress induced by H2O2. These findings indicate that anti-apoptosis with mitochondria-related protection, anti-inflammatory effect, and promote expression of important markers for cell survival may underlie the neuroprotective effect of A2-EPTX-NSm1a in cholinergic rich human cells under oxidative stress, a vital role in the neuronal disorder.

Ozone pollution, oxidative stress, synaptic plasticity, and neurodegeneration

INTRODUCTION

Overpopulation and industrial growth result in an increase in air pollution, mainly due to suspended particulate matter and the formation of ozone. Repeated exposure to low doses of ozone, such as on a day with high air pollution levels, results in a state of chronic oxidative stress, causing the loss of dendritic spines, alterations in cerebral plasticity and in learning and memory mechanisms, and neuronal death and a loss of brain repair capacity. This has a direct impact on human health, increasing the incidence of chronic and degenerative diseases.

DEVELOPMENT

We performed a search of the PubMed, Scopus, and Google Scholar databases for original articles and reviews published between 2000 and 2018 and addressing the main consequences of ozone exposure on synaptic plasticity, information processing in cognitive processes, and the alterations that may lead to the development of neurodegenerative diseases.

CONCLUSIONS

This review describes one of the pathophysiological mechanisms of the effect of repeated exposure to low doses of ozone, which causes loss of synaptic plasticity by producing a state of chronic oxidative stress. This brain function is key to both information processing and the generation of structural changes in neuronal populations. We also address the effect of chronic ozone exposure on brain tissue and the close relationship between ozone pollution and the appearance and progression of neurodegenerative diseases.

Consumption of Cashew (Anacardium occidentale L.) Nuts Counteracts Oxidative Stress and Tissue Inflammation in Mild Hyperhomocysteinemia in Rats

Hyperhomocysteinemia (HHcy) is a methionine metabolism problem that causes a variety of inflammatory illnesses. Oxidative stress is among the processes thought to be involved in the pathophysiology of the damage produced by HHcy. HHcy is likely to involve the dysfunction of several organs, such as the kidney, liver, or gut, which are currently poorly understood. Nuts are regarded as an important part of a balanced diet since they include protein, good fatty acids, and critical nutrients. The aim of this work was to evaluate the anti-inflammatory and antioxidant effects of cashew nuts in HHcy induced by oral methionine administration for 30 days, and to examine the possible pathways involved. In HHcy rats, cashew nuts (100 mg/kg orally, daily) were able to counteract clinical biochemical changes, oxidative and nitrosative stress, reduced antioxidant enzyme levels, lipid peroxidation, proinflammatory cytokine release, histological tissue injuries, and apoptosis in the kidney, colon, and liver, possibly by the modulation of the antioxidant nuclear factor erythroid 2-related factor 2 NRF-2 and inflammatory nuclear factor NF-kB pathways. Thus, the results suggest that the consumption of cashew nuts may be beneficial for the treatment of inflammatory conditions associated with HHcy.

Roles of Non-Coding RNAs as Novel Diagnostic Biomarkers in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting 5%of the elderly population. Currently, the diagnosis of PD is mainly based on clinical features and no definitive diagnostic biomarkers have been identified. The discovery of biomarkers at the earliest stages of PD is of extreme interest. This review focuses on the current findings in the field of circulating non-coding RNAs in PD. We briefly describe the more established circulating biomarkers in PD and provide a more thorough review of non-coding RNAs, in particular microRNAs, long non-coding RNAs and circular RNAs, differentially expressed in PD, highlighting their potential for being considered as biomarkers for diagnosis. Together, these studies hold promise for the use of peripheral biomarkers for the diagnosis of PD.

Homocysteine metabolism as the target for predictive medical approach, disease prevention, prognosis, and treatments tailored to the person

Homocysteine (Hcy) metabolism is crucial for regulating methionine availability, protein homeostasis, and DNA-methylation presenting, therefore, key pathways in post-genomic and epigenetic regulation mechanisms. Consequently, impaired Hcy metabolism leading to elevated concentrations of Hcy in the blood plasma (hyperhomocysteinemia) is linked to the overproduction of free radicals, induced oxidative stress, mitochondrial impairments, systemic inflammation and increased risks of eye disorders, coronary artery diseases, atherosclerosis, myocardial infarction, ischemic stroke, thrombotic events, cancer development and progression, osteoporosis, neurodegenerative disorders, pregnancy complications, delayed healing processes, and poor COVID-19 outcomes, among others. This review focuses on the homocysteine metabolism impairments relevant for various pathological conditions. Innovative strategies in the framework of 3P medicine consider Hcy metabolic pathways as the specific target for in vitro diagnostics, predictive medical approaches, cost-effective preventive measures, and optimized treatments tailored to the individualized patient profiles in primary, secondary, and tertiary care.

Garcinol blocks motor behavioural deficits by providing dopaminergic neuroprotection in MPTP mouse model of Parkinson's disease: involvement of anti-inflammatory response

Although the etiology of Parkinson's disease (PD) is poorly understood, studies in animal models revealed loss of dopamine and the dopaminergic neurons harbouring the neurotransmitter to be the principal cause behind this neuro-motor disorder. Neuroinflammation with glial cell activation is suggested to play a significant role in dopaminergic neurodegeneration. Several biomolecules have been reported to confer dopaminergic neuroprotection in different animal models of PD, owing to their anti-inflammatory potentials. Garcinol is a tri-isoprenylated benzophenone isolated from Garcinia sp. and accumulating evidences suggest that this molecule could provide neuroprotection by modulating oxidative stress and inflammation. However, direct evidence of dopaminergic neuroprotection by garcinol in the pre-clinical model of PD is not yet reported. The present study aims to investigate whether administration of garcinol in the MPTP mouse model of PD may ameliorate the cardinal motor behavioural deficits and prevent the loss of dopaminergic neurons. As expected, garcinol blocked the parkinsonian motor behavioural deficits which include akinesia, catalepsy, and rearing anomalies in the mice model. Most importantly, the degeneration of dopaminergic cell bodies in the substantia nigra region was significantly prevented by garcinol. Furthermore, garcinol reduced the inflammatory marker, glial fibrillary acidic protein, in the substantia nigra region. Since glial hyperactivation-mediated inflammation is inevitably associated with the loss of dopaminergic neurons, our study suggests the anti-inflammatory role of garcinol in facilitating dopaminergic neuroprotection in PD mice. Hence, in the light of the present study, it is suggested that garcinol is an effective anti-parkinsonian agent to block motor behavioural deficits and dopaminergic neurodegeneration in PD.

Ozone pollution, oxidative stress, synaptic plasticity, and neurodegeneration

INTRODUCTION

Overpopulation and industrial growth result in an increase in air pollution, mainly due to suspended particulate matter and the formation of ozone. Repeated exposure to low doses of ozone, such as on a day with high air pollution levels, results in a state of chronic oxidative stress, causing the loss of dendritic spines, alterations in cerebral plasticity and in learning and memory mechanisms, and neuronal death and a loss of brain repair capacity. This has a direct impact on human health, increasing the incidence of chronic and degenerative diseases.

DEVELOPMENT

We performed a search of the PubMed, Scopus, and Google Scholar databases for original articles and reviews published between 2000 and 2018 and addressing the main consequences of ozone exposure on synaptic plasticity, information processing in cognitive processes, and the alterations that may lead to the development of neurodegenerative diseases.

CONCLUSIONS

This review describes one of the pathophysiological mechanisms of the effect of repeated exposure to low doses of ozone, which causes loss of synaptic plasticity by producing a state of chronic oxidative stress. This brain function is key to both information processing and the generation of structural changes in neuronal populations. We also address the effect of chronic ozone exposure on brain tissue and the close relationship between ozone pollution and the appearance and progression of neurodegenerative diseases.

Four Weeks of Aerobic Training Affects Cardiac Tissue Matrix Metalloproteinase, Lactate Dehydrogenase and Malate Dehydrogenase Enzymes Activities, and Hepatorenal Biomarkers in Experimental Hyperhomocysteinemia in Rats

The aim of this study was to investigate the effect of the application of homocysteine as well as its effect under the condition of aerobic physical activity on the activities of matrix metalloproteinases (MMP), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) in cardiac tissue and on hepato-renal biochemical parameters in sera of rats. Male Wistar albino rats were divided into four groups (n = 10, per group): C: 0.9% NaCl 0.2 mL/day subcutaneous injection (s.c.); H: homocysteine 0.45 µmol/g b.w./day s.c.; CPA saline (0.9% NaCl 0.2 mL/day s.c.) and a program of physical activity on a treadmill; and HPA homocysteine (0.45 µmol/g b.w./day s.c.) and a program of physical activity on a treadmill. Subcutaneous injection of substances was applied 2 times a day at intervals of 8 h during the first two weeks of experimental protocol. Hcy level in serum was significantly higher in the HPA group compared to the CPA group (p < 0.05). Levels of glucose, proteins, albumin, and hepatorenal biomarkers were higher in active groups compared with the sedentary group. It was demonstrated that the increased activities of LDH (mainly caused by higher activity of isoform LDH2) and mMDH were found under the condition of homocysteine-treated rats plus aerobic physical activity. Independent application of homocysteine did not lead to these changes. Physical activity leads to activation of MMP-2 isoform and to increased activity of MMP-9 isoform in both homocysteine-treated and control rats.

Ameliorative effect of white tea from 50-year-old tree of Camellia sinensis L. (Theaceae) on kidney damage in diabetic mice via SIRT1/AMPK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic kidney damage (DKD) is one of the most common complications of diabetes, which is known as a chronic inflammatory kidney disease caused by persistent hyperglycemia. White tea was originally used as a folk medicine to treat measles in ancient China. What arouses our interest is that there is a traditional method to treat diabetes with white tea taken from over 30-year-old tree of Camellia sinensis L. However, there are few reports on the renal protection of white tea.

AIM OF THE STUDY

This present study was designed to study the potential protective effects of white tea (WT) and old tree white tea (OTWT) on high-fat-diet (HFD) combined with streptozotocin (STZ)-induced type 2 diabetic mice to explore the possible mechanism of WT/OTWT against DKD.

MATERIALS AND METHODS

C57BL/6 mice were randomly divided into four groups: NC, T2D, WT (400 mg/kg·b.w, p.o.), OTWT (400 mg/kg·b.w, p.o.). Diabetes was established in all groups except NC group, by six weeks of HFD feeding combined with STZ (50 mg/kg, i.p.) for 3 times, treatments were administered for six weeks and then all the animals were decapitated; kidney tissues and blood samples were collected for the further analysis, including: levels of insulin, lipid metabolism (TG, TC, HDL, LDL, FFA), antioxidative enzymes (catalase (CAT), super oxide dismutase (SOD), glutathione peroxidase (GPx)), blood urea nitrogen (BUN) and creatine, inflammatory cytokines (TNF-α, IL-1β, COX-2, iNOS, MCP-1), advanced glycation end products (AGE), receptor of AGE (RAGE), Nrf2, AMPK, SIRT1, and PGC-1α. H&E, PAS and Masson staining were performed to examine the histopathological alterations of the kidneys.

RESULTS

Our data showed that WT and OTWT reversed the abnormal serum lipids (TG, TC, HDL, LDL, FFA) in T2D mice, upregulated antioxidative enzymes levels (CAT, SOD, GPx) and inhibit the excessive production of proinflammatory mediators (including MCP-1, TNF-α, IL1β, COX-2 and iNOS) by varying degrees, and OTWT was more effective. In histopathology, OTWT could significantly alleviate the accumulation of renal AGE in T2D mice, thereby improving the structural changes of the kidneys, such as glomerular hypertrophy, glomerular basement membrane thickening and kidney FIbrosis.

CONCLUSIONS

Both WT and OTWT could alleviate the diabetic changes in T2D mice via hypoglycemic, hypolipidemic, anti-oxidative and anti-inflammatory effects, while OTWT was more evident. OTWT could prominently alleviate the accumulation of AGE in the kidneys of T2D mice, thereby ameliorating the renal oxidative stress and inflammatory damage, which was associated with the activation of SIRT1/AMPK pathway.

Hyperhomocysteinemia alters cytokine gene expression, cytochrome c oxidase activity and oxidative stress in striatum and cerebellum of rodents

AIMS

Homocysteine has been linked to neurodegeneration and motor function impairments. In the present study, we evaluate the effect of chronic mild hyperhomocysteinemia on the motor behavior (motor coordination, functional performance, and muscular force) and biochemical parameters (oxidative stress, energy metabolism, gene expression and/or protein abundance of cytokine related to the inflammatory pathways and acetylcholinesterase) in the striatum and cerebellum of Wistar male rats.

MAIN METHODS

Rodents were submitted to one injection of homocysteine (0.03 μmol Hcy/g of body weight) between 30th and 60th postnatal days twice a day. After hyperhomocysteinemia induction, rats were submitted to horizontal ladder walking, beam balance, suspension, and vertical pole tests and/or euthanized to brain dissection for biochemical and molecular assays.

KEY FINDINGS

Chronic mild hyperhomocysteinemia did not alter motor function, but induced oxidative stress and impaired mitochondrial complex IV activity in both structures. In the striatum, hyperhomocysteinemia decreased TNF-α gene expression and increased IL-1β gene expression and acetylcholinesterase activity. In the cerebellum, hyperhomocysteinemia increased gene expression of TNF-α, IL-1β, IL-10, and TGF-β, while the acetylcholinesterase activity was decreased. In both structures, hyperhomocysteinemia decreased acetylcholinesterase protein abundance without altering total p-NF-κB, NF-κB, Nrf-2, and cleaved caspase-3.

SIGNIFICANCE

Chronic mild hyperhomocysteinemia compromises several biochemical/molecular parameters, signaling pathways, oxidative stress, and chronic inflammation in the striatum and cerebellum of rats without impairing motor function. These alterations may be related to the mechanisms in which hyperhomocysteinemia has been linked to movement disorders later in life and neurodegeneration.

Metabolomics: small molecules that matter more

Metabolomics, an analytical study with high-throughput profiling, helps to understand interactions within a biological system. Small molecules, called metabolites or metabolomes with the size of <1500 Da, depict the status of a biological system in a different manner. Currently, we are in need to globally analyze the metabolome and the pathways involved in healthy, as well as diseased conditions, for possible therapeutic applications. Metabolome analysis has revealed high-abundance molecules during different conditions such as diet, environmental stress, microbiota, and disease and treatment states. As a result, it is hard to understand the complete and stable network of metabolites of a biological system. This review helps readers know the available techniques to study metabolomics in addition to other major omics such as genomics, transcriptomics, and proteomics. This review also discusses the metabolomics in various pathological conditions and the importance of metabolomics in therapeutic applications.

Long Non-coding RNAs in Parkinson's Disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder and is associated with a range of motor and non-motor clinical symptoms. The underlying molecular pathogenesis of PD involves a variety of pathways and mechanisms, including α-synuclein proteostasis, mitochondrial dysfunction, oxidative stress, autophagy and apoptosis, neuroinflammation, and epigenetic regulation. Long non-coding RNAs (lncRNAs) are involved in the regulation of multiple pathological processes of PD. In this review, we provide an overview of large-scale studies on lncRNA expression profiling in PD patients and models, as well as highlight the impacts of lncRNAs on the pathogenesis of PD, which could provide basic information regarding the putative lncRNA-based biomarkers and therapeutic targets for the early diagnosis and treatment strategies for PD.

Involvements of Hyperhomocysteinemia in Neurological Disorders

Homocysteine (HCY), a physiological amino acid formed when proteins break down, leads to a pathological condition called hyperhomocysteinemia (HHCY), when it is over a definite limit. It is well known that an increase in HCY levels in blood, can contribute to arterial damage and several cardiovascular disease, but the knowledge about the relationship between HCY and brain disorders is very poor. Recent studies demonstrated that an alteration in HCY metabolism or a deficiency in folate or vitamin B12 can cause altered methylation and/or redox potentials, that leads to a modification on calcium influx in cells, or into an accumulation in amyloid and/or tau protein involving a cascade of events that culminate in apoptosis, and, in the worst conditions, neuronal death. The present review will thus summarize how much is known about the possible role of HHCY in neurodegenerative disease.

Improved functional and histochemical outcomes in l-DOPA plus tolcapone treated VMAT2-deficient mice

Parkinson disease is typically treated with L-3,4-dihydroxyphenylalanine (or levodopa) co-prescribed with concentration stabilizers to prevent undesired motor fluctuations. However, the beneficial role of the chronic combined therapy on disease progression has not been thoroughly explored. We hypothesized that tolcapone, a catechol-O-methyl-transferase inhibitor, co-administered with levodopa may offer beneficial long-term disease-modifying effects through its dopamine stabilization actions. Here, we followed vesicular monoamine transporter 2-deficient and wild-type mice treated twice daily per os with vehicle, levodopa (20 mg/kg), tolcapone (15 mg/kg) or levodopa (12.5 mg/kg) + tolcapone (15 mg/kg) for 17 weeks. We assessed open field, bar test and rotarod performances at baseline and every 4th week thereafter, corresponding to OFF-medication weeks. Finally, we collected coronal sections from the frontal caudate-putamen and determined the reactivity level of dopamine transporter. Vesicular monoamine transporter 2-deficient mice responded positively to chronic levodopa + tolcapone intervention in the bar test during OFF-periods. Neither levodopa nor tolcapone interventions offered significant improvements on their own. Similarly, chronic levodopa + tolcapone intervention was associated with partially rescued dopamine transporter levels, whereas animals treated solely with levodopa or tolcapone did not present this effect. Interestingly, 4-month progression of bar test scores correlated significantly with dopamine-transporter-label density. Overall, we observed a moderate functional and histopathological improvement effect by chronic dopamine replacement when combined with tolcapone in vesicular monoamine transporter 2-deficient mice. Altogether, chronic stabilization of dopamine levels by catechol-O-methyl-transferase inhibition, besides its intended immediate actions, arises as a potential long-term beneficial approach during the progression of Parkinson disease.

Glial cells in Parkinson´s disease: protective or deleterious?

Glial cells have been identified more than 100 years ago, and are known to play a key role in the central nervous system (CNS) function. A recent piece of evidence is emerging showing that in addition to the capacity of CNS modulation and homeostasis, glial cells are also being looked like as a promising cell source not only to study CNS pathologies initiation and progression but also to the establishment and development of new therapeutic strategies. Thus, in the present review, we will discuss the current evidence regarding glial cells' contribution to neurodegenerative diseases as Parkinson's disease, providing cellular, molecular, functional, and behavioral data supporting its active role in disease initiation, progression, and treatment. As so, considering their functional relevance, glial cells may be important to the understanding of the underlying mechanisms regarding neuronal-glial networks in neurodegeneration/regeneration processes, which may open new research opportunities for their future use as a target or treatment in human clinical trials.

Mir-141-3p Regulates Apoptosis and Mitochondrial Membrane Potential via Targeting Sirtuin1 in a 1-Methyl-4-Phenylpyridinium in vitro Model of Parkinson's Disease

Objectives

Parkinson's disease (PD) is a common neurodegenerative disease characterized by the loss of midbrain dopaminergic neurons in the substantia nigra. The present study investigated miR-141-3p/sirtuin1 (SIRT1) activity in a 1-methyl-4-phenylpyridinium- (MPP+-) induced PC12-cell model of PD.

Methods

PC12 cells were exposed to MMP+ following induction of differentiation by nerve growth factor (NGF). miR-141-3p and SIRT1 expressions were examined using RT-qPCR and western blot. Cell viability was evaluated using the MTT assay. Apoptosis percentage, reactive oxygen species (ROS) production, and mitochondrial membrane potential (Δψm) were evaluated using flow cytometry. Expression of Nuclear factor-kappa B- (NF-κB-) related proteins was determined by western blot. Bioinformatic analysis, RT-qPCR, and luciferase reporter assay were used to confirm the interaction between miR-141-3p and SIRT1.

Results

miR-141-3p was upregulated, and SIRT1 was downregulated in MPP+-treated PC12 cells. MPP+ treatment also upregulated nitric oxide synthase 1 (Nos1) and α-synuclein. miR-141-3p induced apoptosis, oxidative stress, mitochondrial dysfunction, and downregulated the SIRT1 mRNA expression. The luciferase reporter assay showed that SIRT1 was the target of miR-141-3p. SIRT1 transfection attenuated apoptosis, ROS production and maintained Δψm. SIRT1 also downregulated Nos1, tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), interleukin 6(IL-6) and upregulated B cell lymphoma 2 (Bcl-2) protein. In addition, SIRT1 activator resveratrol blocked the effects of miR-141-3p mimic on Nos1, α-synuclein, and mitochondrial membrane potential. SIRT1 inhibitor sirtinol reversed the biological effects of miR-141-3p.

Conclusion

Increased miR-141-3p induced apoptosis, oxidative stress, and mitochondrial dysfunction in MPP+-treated PC12 cells by directly targeting the SIRT1 expression. Our study provided a potential therapeutic strategy for PD.

Role of homocysteine in the development and progression of Parkinson's disease

Homocysteine is an essential intermediate product of biochemical reactions that is present in various tissues of the human body. Homocysteine may be associated with the development and progression of Parkinson’s disease. Plasma homocysteine levels in patients with Parkinson’s disease are elevated compared to those of healthy individuals. High homocysteine drives PD development and progression while aggregating the clinical symptoms of PD patients. The relationship between PD and homocysteine involves multiple pathways, including nerve cell apoptosis, oxidative stress, and DNA damage. This is crucial for explaining how high homocysteine drives the PD procession. Elevated homocysteine level during PD development and progression offers a new strategy for the diagnosis and treatment of this disease.

Homocysteine and Mitochondria in Cardiovascular and Cerebrovascular Systems

Elevated concentration of homocysteine (Hcy) in the blood plasma, hyperhomocysteinemia (HHcy), has been implicated in various disorders, including cardiovascular and neurodegenerative diseases. Accumulating evidence indicates that pathophysiology of these diseases is linked with mitochondrial dysfunction. In this review, we discuss the current knowledge concerning the effects of HHcy on mitochondrial homeostasis, including energy metabolism, mitochondrial apoptotic pathway, and mitochondrial dynamics. The recent studies suggest that the interaction between Hcy and mitochondria is complex, and reactive oxygen species (ROS) are possible mediators of Hcy effects. We focus on mechanisms contributing to HHcy-associated oxidative stress, such as sources of ROS generation and alterations in antioxidant defense resulting from altered gene expression and post-translational modifications of proteins. Moreover, we discuss some recent findings suggesting that HHcy may have beneficial effects on mitochondrial ROS homeostasis and antioxidant defense. A better understanding of complex mechanisms through which Hcy affects mitochondrial functions could contribute to the development of more specific therapeutic strategies targeted at HHcy-associated disorders.

Hydrogen Sulfide Alleviates Anxiety, Motor, and Cognitive Dysfunctions in Rats with Maternal Hyperhomocysteinemia via Mitigation of Oxidative Stress

Hydrogen sulfide (H₂S) is endogenously produced from sulfur containing amino acids, including homocysteine and exerts neuroprotective effects. An increase of homocysteine during pregnancy impairs fetal growth and development of the offspring due to severe oxidative stress. We analyzed the effects of the H₂S donor—sodium hydrosulfide (NaHS) administered to female rats with hyperhomocysteinemia (hHcy) on behavioral impairments and levels of oxidative stress of their offspring. Rats born from females fed with control or high methionine diet, with or without H₂S donor injections were investigated. Rats with maternal hHcy exhibit increased levels of total locomotor activity and anxiety, decreased muscle endurance and motor coordination, abnormalities of fine motor control, as well as reduced spatial memory and learning. Oxidative stress in brain tissues measured by activity of glutathione peroxidases and the level of malondialdehyde was higher in rats with maternal hHcy. Concentrations of H₂S and the activity and expression of the H₂S generating enzyme—cystathionine-beta synthase—were lower compared to the control group. Administration of the H₂S donor to females with hHcy during pregnancy prevented behavioral alterations and oxidative stress of their offspring. The acquisition of behavioral together with biochemical studies will add to our knowledge about homocysteine neurotoxicity and proposes H₂S as a potential agent for therapy of hHcy associated disorders.

MiR-302b-5p enhances the neuroprotective effect of IGF-1 in methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease by regulating inducible nitric-oxide synthase

Parkinson's disease (PD) is a neurodegenerative disease which results in damage in neuronal cells. Insulin-like growth factor (IGF)-1 was previously reported to play a role of neuroprotection in some diseases. Nitric oxide (NO) can also regulate neuronal cells. However, the mechanisms underlying IGF-1 and NO in PD still need to be elucidated. In present study, we explored the interaction between IGF-1 and inducible Nitric-Oxide Synthase (iNOS) in PD progression. We firstly constructed PD models by methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or MPP⁺ treatment. Then RT-qPCR revealed that IGF-1 expression was downregulated while iNOS expression was upregulated in MPTP model. Moreover, IGF-1 elevation or iNOS depletion enhanced cell viability and blocked cell apoptosis. Rescue assay disclosed iNOS overexpression reversed the effect on viability and apoptosis mediated by IGF-1 upregulation. Furthermore, IGF-1 was identified to positively regulate miR-302b-5p which could target iNOS. MiR-302b-5p could abolish the inhibitory function IGF-1 exerted on cell apoptosis and iNOS could counteract miR-302b-5p upregulation-triggered inhibition on cell apoptosis as well. Besides, we observed the deficiency of miR-302b-5p improved the lesioned neurobehavior of MPTP-treated mice. To sum up, present study proved that miR-302b-5p enhanced the neuroprotective effect of IGF-1 in MPTP-induced PD by regulating iNOS, recommending a novel therapeutic target for PD treatment. SIGNIFICANCE OF THE STUDY: In this study, we mainly explored that IGF-1 was decreased while iNOS was boosted in MPTP-induced PD mice model; IGF-1 suppressed while iNOS promoted MPP⁺ -induced toxicity and apoptosis in SH-SY5Y cells; miR-302b-5p ehanhced the neuroprotective effect of IGF-1 via targeting Inos; deficiency of miR-302b-5p improved the lesioned neurobehavior of MPTP-treated mice.

Leptin mediates protection of hydrogen sulfide against 6-hydroxydopamine-induced Parkinson's disease: Involving enhancement in Warburg effect

BACKGROUND

Hydrogen sulfide (H₂S) has therapeutic effects on Parkinson's disease (PD). Warburg effect, namely aerobic glycolysis, is benefit to PD. Leptin, a hormone secreted in adipose, plays an important role in the treatment of PD.

OBJECTIVE

To determine whether the mechanism underlying protection of H₂S against PD is involved in promoting Warburg effect via upregulation of leptin.

METHODS

We set a PD model via unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA) in Sprague Dawley rat. PD-like behavior was analyzed by apomorphine-induced rotations, open field activity test, stepping test and cylinder test. Dopaminergic neurons were detected by immunohistochemistry. The expressions of Hexokinase-2, pyruvate kinase M-2, lactate dehydrogenase, pyruvate dehydrogenase kinase, pyruvate dehydrogenase, and leptin were measured by Western blot. Lactate dehydrogenase (LDHA) activity was monitored by ELISA. The lactate content was measured by lactate assay kit.

RESULTS

We showed that NaHS (a donor of H₂S) prevented 6-OHDA-induced PD-like behaviors as well as the loss of dopaminergic neurons. We also found that NaHS enhanced the Warburg effect and upregulated leptin expression in the substantia nigra of 6-OHDA-exposed rats. While, inhibited leptin signaling by OBR13-A reversed the protections of H₂S against 6-OHDA-exerted PD-like behaviors and the loss of dopaminergic neurons in the substantia nigra, and abolished H₂S-enhanced in the Warburg effect in the substantia nigra.

CONCLUSION

These data indicated that leptin mediates the protection of H₂S against PD, which involves enhancing the Warburg effect of the substantia nigra.

Inhibitory potential of plant secondary metabolites on anti-Parkinsonian drug targets: Relevance to pathophysiology, and motor and non-motor behavioural abnormalities

Parkinson's disease (PD), a progressive neurodegenerative motor disorder, is caused due to the loss of dopaminergic neurons in the substantia nigra pars compacta region of mid-brain and the resultant depletion of the levels of the neurotransmitter dopamine. Although the pathophysiology of the disease is least understood, studies in animal models revealed oxidative stress, mitochondrial dysfunction and inflammation to be the major contributors. Dopamine replenishment therapy by oral administration of L-DOPA, the precursor of dopamine remains to be the therapeutic gold-standard for symptomatic treatment of PD. In addition, use of inhibitors of dopamine metabolizing enzymes (viz. monoamine oxidase-B: MAO-B; and catechol-O-methyltransferase: COMT) are the other strategies for amelioration of the motor abnormalities. Further, PD is associated with non-motor behavioural abnormalities as well, including cognitive impairment and mood disorders, which are caused due to cholinergic neurodegeneration, and thus inhibition of Acetylcholinesterase (AChE) is suggested. However, the currently used drugs against the three crucial enzymes (MAO-B, COMT and AChE) elicit several side effects, and thus the search for novel compounds continues, and plant-based compounds have promising potential in this regard. In the present study, we have used computational modeling to determine the efficiency of 40 plant-based natural products in inhibiting the three anti-Parkinsonian drug targets. Further, statistical analysis was performed to identify the properties of the compounds which are crucial for inhibition of the enzymes. While all the phytochemicals showed potential in inhibiting the enzymes, Rutin, Demethoxycurcumin and Acteoside were found to be most effective inhibitors of MAO-B, COMT and AChE respectively. Since most of the compounds are established anti-oxidant and anti-inflammatory molecules, they are surmised to confer neuroprotection in PD, and prevent progression of the disease.

Hydrogen sulfide attenuates hyperhomocysteinemia-induced mitochondrial dysfunctions in brain

Hyperhomocysteinemia (HHcy) has been implicated in the development of neurodegenerative conditions and mild cognitive disorders. Mitochondrial dysfunctions are the major mechanisms involved in homocysteine (Hcy)-induced neurotoxicity. Although, hydrogen sulfide has been reported as potent antioxidant, its effects on Hcy-induced mitochondrial dysfunctions have not been studied. Therefore, the present study has been designed to evaluate the protective effect of NaHS on Hcy-induced mitochondrial dysfunctions in brain. NaHS supplementation decreased reactive oxygen species and nitrite levels in the cortex and hippocampus of animals with HHcy. NaHS supplementation increased the activity of mitochondrial electron transport chain components; NADH dehydrogenase, cytochrome c oxidase and F0-F1 ATPase in the cortex and hippocampus of HHcy animals along with in-gel activity of complex I - complex V in the mitochondria isolated from the cortex and hippocampus of HHcy animals. Moreover, NaHS supplementation also increased the mitochondrial complex I, II and IV mediated oxygen consumption rate in Hcy treated mitochondria. NaHS administration prevented the Hcy-induced mitochondrial damage as suggested by the decreased mitochondrial swelling in the cortex and hippocampus of HHcy animals. NaHS supplementation decreased the activity of lactate dehydrogenase isozymes (1-5) in the brain regions of HHcy animals. The expression of protein kinase c δ was also decreased in the brain regions of HHcy animals following NaHS supplementation. This was accompanied by reduced activity of caspase-3 indicating anti-apoptotic effect of H₂S. Taken together, the findings suggest that H₂S supplementation ameliorates Hcy-induced oxidative stress and mitochondrial dysfunctions suggesting H₂S releasing drugs may be a novel therapeutic approach to treat HHcy associated neurological disorders.

The metabolic face of migraine - from pathophysiology to treatment

Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.

5-S-cysteinyl-dopamine, a neurotoxic endogenous metabolite of dopamine: Implications for Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide and is characterized for being an idiopathic and multifactorial disease. Extensive research has been conducted to explain the origin of the disease, but it still remains elusive. It is well known that dopamine oxidation, through the endogenous formation of toxic metabolites, is a key process in the activation of a cascade of molecular events that leads to cellular death in the hallmark of PD. Thio-catecholamines, such as 5-S-cysteinyl-dopamine, 5-S-glutathionyl-dopamine and derived benzothiazines, are endogenous metabolites formed in the dopamine oxidative degradation pathway. Those metabolites have been shown to be highly toxic to neurons in the substantia nigra pars compacta, activating molecular mechanisms that ultimately lead to neuronal death. In this review we describe the origin, formation and the toxic effects of 5-S-cysteinyl-dopamine and its oxidative derivatives that cause death to dopaminergic neurons. Furthermore, we correlate the formation of those metabolites with the neurodegeneration progress in PD. In addition, we present the reported neuroprotective strategies of products that protect against the cellular damage of those thio-catecholamines. Finally, we discuss the advantages in the use of 5-S-cysteinyl-dopamine as a potential biomarker for PD.

Garcinol, a multifaceted sword for the treatment of Parkinson's disease

Garcinol, the principal phytoconstituent of plants belonging to the genus Garcinia, is known for its anti-oxidant as well as anti-inflammatory properties, which can be extended to its possible neuroprotective role. Recent reports disseminate the capacity of garcinol to influence neuronal growth and survival, alter the neurochemical status in brain, as well as regulate memory and cognition. The concomitant neuro-rescue property of garcinol may render it as an effective compound in Parkinson's disease (PD) therapeutics since it is capable of ameliorating the related pathophysiological changes. Emerging pieces of evidence linking histone acetylation defects to the progression of neurodegenerative diseases provide an effective basis for targeting PD. Hyperacetylation of histones has been reported in Parkinsonian brain, which demands the use of pharmacological inhibitors of histone acetyltransferases (HAT). Garcinol serves as a potent natural HAT inhibitor and has unveiled promising results in molecular interaction studies against Monoamine oxidase B (MAO-B) and Catechol-O-Methyltransferase (COMT), as well as in L-DOPA induced dyskinesia. This review highlights the prospective implications of garcinol as a novel anti-Parkinsonian agent, and establishes a bridge between histone acetylation defects and the pathological aspects of PD.

Hyperhomocysteinemia-induced death of retinal ganglion cells: The role of Müller glial cells and NRF2

Hyperhomocysteinemia (Hhcy), or increased levels of the excitatory amino acid homocysteine (Hcy), is implicated in glaucoma, a disease characterized by increased oxidative stress and loss of retinal ganglion cells (RGCs). Whether Hhcy is causative or merely a biomarker for RGC loss in glaucoma is unknown. Here we analyzed the role of NRF2, a master regulator of the antioxidant response, in Hhcy-induced RGC death in vivo and in vitro. By crossing Nrf2^−/− mice and two mouse models of chronic Hhcy (Cbs^+/- and Mthfr^+/- mice), we generated Cbs^+/-Nrf2^−/− and Mthfr^+/-Nrf2^−/− mice and performed systematic analysis of retinal architecture and visual acuity followed by assessment of retinal morphometry and gliosis. We observed significant reduction of inner retinal layer thickness and reduced visual acuity in Hhcy mice lacking NRF2. These functional deficits were accompanied by fewer RGCs and increased gliosis. Given the key role of Müller glial cells in maintaining RGCs, we established an ex-vivo indirect co-culture system using primary RGCs and Müller cells. Hhcy-exposure decreased RGC viability, which was abrogated when cells were indirectly cultured with wildtype (WT) Müller cells, but not with Nrf2^−/− Müller cells. Exposure of WT Müller cells to Hhcy yielded a robust mitochondrial and glycolytic response, which was not observed in Nrf2^−/− Müller cells. Taken together, the in vivo and in vitro data suggest that deleterious effects of Hhcy on RGCs are likely dependent upon the health of retinal glial cells and the availability of an intact retinal antioxidant response mechanism.

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Oxidative stress is linked to homocysteine (Hcy)-induced retinal ganglion cell death.

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NRF2's role in protecting ganglion cells from excess Hcy was studied in vitro/vivo.

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Hyper-Hcy mice were crossed with Nrf2^−/− mice to study retinal function/structure.

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Ganglion cells co-cultured with primary WT Müller glial cells survived Hcy treatment.

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Nrf2^−/− Müller cells did not afford neuroprotective advantage to Hcy-treated cells.

Protein carbonylation in dopaminergic cells exposed to rotenone

Rotenone is an environmental neurotoxin that induces degeneration of dopaminergic neurons and the most common features of Parkinson's disease in animal models. It acts as a mitochondrial complex I inhibitor that impairs cellular respiration, with consequent increase of reactive oxygen species and oxidative stress. This study evaluates the rotenone-induced oxidative damage in PC12 cells, focusing particularly on protein oxidation. The identification of specific carbonylated proteins highlighted putative alterations of important cellular processes possibly associated with Parkinson's disease. Carbonylation of ATP synthase and of enzymes acting in pyruvate and glucose metabolism suggested a failure of mechanisms ensuring cellular energy supply. Concomitant oxidation of cytoskeletal proteins and of enzymes involved in the synthesis of neuroactive molecules indicated alterations of the neurotransmission system. Carbonylation of chaperon proteins as well as of proteins acting in the autophagy-lysosome pathway and the ubiquitin-proteasome system suggested the possible formation of cytosolic unfolded protein inclusions as result of defective processes assisting recovery/degradation of damaged molecules. In conclusion, this study originally evidences specific protein targets of rotenone-induced oxidative damage, suggesting some possible molecular mechanisms involved in rotenone toxicity.

An appraisal of folates as key factors in cognition and ageing-related diseases

Folic acid (FA) is often consumed as a food supplement and can be found in fortified staple foods in various western countries. Even though FA supplementation during pregnancy is known to prevent severe congenital anomalies in the developing child (e.g., neural tube defects), much less is known about its influence on cognition and neurological functioning. In this review, we address the advances in this field and situate how folate intake during pregnancy, postnatal life, adulthood and in the elderly affects cognition. In addition, an association between folate status and ageing, dementia and other neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis is discussed. While its role in the incidence and severity of these diseases is becoming apparent, the underlying action of folates and related metabolites remains elusive. Finally, the potential of FA as a nutraceutical has been proposed, although the efficacy will highly depend on the interplay with other micronutrients, the disease stage and the duration of supplementation. Hence, the lack of consistent data urges for more animal studies and (pre)clinical trials in humans to ascertain a potential beneficial role for folates in the treatment or amelioration of cognitive decline and ageing-related disorders.