Dysregulation of glutathione homeostasis in neurodegenerative diseases

Novel Neuroprotective Potential of Crocin in Neurodegenerative Disorders: An Illustrated Mechanistic Review

Neurodegenerative disorders are characterized by mitochondrial dysfunction and subsequently oxidative stress, inflammation, and apoptosis that contribute to neuronal cytotoxicity and degeneration. Recent studies reported that crocin, a carotenoid chemical compound common in crocus and gardenia flowers, has protective effects in neurodegenerative disorders due to its anti-oxidative, anti-inflammatory, and anti-apoptotic properties in the nervous system. This article reviews the new experimental, clinical, and pharmacological studies on the neuroprotective properties of crocin and its potential mechanisms to modulate metabolic oxidative stress and inflammation in neurodegenerative disorders.

Anti-inflammatory and Neuroprotective Agents in Clinical Trials for CNS Disease and Injury: Where Do We Go From Here?

Neurological disorders are major contributors to death and disability worldwide. The pathology of injuries and disease processes includes a cascade of events that often involve molecular and cellular components of the immune system and their interaction with cells and structures within the central nervous system. Because of this, there has been great interest in developing neuroprotective therapeutic approaches that target neuroinflammatory pathways. Several neuroprotective anti-inflammatory agents have been investigated in clinical trials for a variety of neurological diseases and injuries, but to date the results from the great majority of these trials has been disappointing. There nevertheless remains great interest in the development of neuroprotective strategies in this arena. With this in mind, the complement system is being increasingly discussed as an attractive therapeutic target for treating brain injury and neurodegenerative conditions, due to emerging data supporting a pivotal role for complement in promoting multiple downstream activities that promote neuroinflammation and degeneration. As we move forward in testing additional neuroprotective and immune-modulating agents, we believe it will be useful to review past trials and discuss potential factors that may have contributed to failure, which will assist with future agent selection and trial design, including for complement inhibitors. In this context, we also discuss inhibition of the complement system as a potential neuroprotective strategy for neuropathologies of the central nervous system.

Rational design of an ESIPT-based fluorescent probe for selectively monitoring glutathione in live cells and zebrafish

Glutathione (GSH), an extremely important antioxidant, is a major participant in maintaining redox homeostasis and tightly associated with various clinical diseases. Thus, accurate and rapid detection of intracellular GSH is imperative to elucidate its role in physiological and pathological processes. Herein, by modifying 2-(2'-hydroxyphenyl) benzothiazole (HBT) scaffold, we developed an excited-state intramolecular proton transfer (ESIPT)-based fluorescent probe BTFMD for tracking GSH, which exhibited good selectivity, excellent water solubility, a large Stokes shift (181 nm) and fast response rate (within 10 min). Furthermore, the probe was successfully applied for imaging of endogenous GSH in live cells and zebrafish, and probing into the role of GSH in the development of cancer and Parkinson's disease.

Treatment of dilated cardiomyopathy in a mouse model of Friedreich's ataxia using N-acetylcysteine and identification of alterations in microRNA expression that could be involved in its pathogenesis

Deficient expression of the mitochondrial protein, frataxin, leads to a deadly cardiomyopathy. Our laboratory reported the master regulator of oxidative stress, nuclear factor erythroid 2-related factor-2 (Nrf2), demonstrates marked down-regulation after frataxin deletion in the heart. This was due, in part, to a pronounced increase in Keap1. To assess if this can be therapeutically targeted, cells were incubated with N-acetylcysteine (NAC), or buthionine sulfoximine (BSO), which increases or decreases glutathione (GSH), respectively, or the NRF2-inducer, sulforaphane (SFN). While SFN significantly (p < 0.05) induced NRF2, KEAP1 and BACH1, NAC attenuated SFN-induced NRF2, KEAP1 and BACH1. The down-regulation of KEAP1 by NAC was of interest, as Keap1 is markedly increased in the MCK conditional frataxin knockout (MCK KO) mouse model and this could lead to the decreased Nrf2 levels. Considering this, MCK KO mice were treated with i.p. NAC (500- or 1500-mg/kg, 5 days/week for 5-weeks) and demonstrated slightly less (p > 0.05) body weight loss versus the vehicle-treated KO. However, NAC did not rescue the cardiomyopathy. To additionally examine the dys-regulation of Nrf2 upon frataxin deletion, studies assessed the role of microRNA (miRNA) in this process. In MCK KO mice, miR-144 was up-regulated, which down-regulates Nrf2. Furthermore, miRNA screening in MCK KO mice demonstrated 23 miRNAs from 756 screened were significantly (p < 0.05) altered in KOs versus WT littermates. Of these, miR-21*, miR-34c*, and miR-200c, demonstrated marked alterations, with functional clustering analysis showing they regulate genes linked to cardiac hypertrophy, cardiomyopathy, and oxidative stress, respectively.

Ropinirole silver nanocomposite attenuates neurodegeneration in the transgenic Drosophila melanogaster model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease due to the degeneration of dopaminergic neurons in substantia nigra pars compacta of the mid brain. The present study investigates the neuro-protective role of synthesized ropinirole silver nanocomposite (RPAgNC) in Drosophila model of PD. α-synuclein accumulation in the brain of flies (PD flies) leads to the damage of dopaminergic neurons, dopamine depletion, impaired muscular coordination, memory decline and increase in oxidative stress. Ingestion of the RPAgNC by Drosophila significantly prevented the neuronal degeneration compared to only ropinirole. The results confirm that the RPAgNC exerts more neuro-protective effect compared to dopamine agonist i.e. ropinirole as such drug in experimental PD flies. This article is part of the special issue entitled 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

The Effect of a Rat Diet Without Added Cu on Redox Status in Tissues and Epigenetic Changes in the Brain

The aim of the study was to determine whether feeding rats a diet without added Cu increases oxidation of macromolecules in tissues, as well as epigenetic changes in the brain. The rats were divided into two groups: the Cu-6.5 group which was fed a diet with a standard content of Cu in mineral mixture – 6.5 mg Cu from CuCO3 per kg of diet; and the Cu-0 group which was fed a diet with a mineral mix without Cu supplementation. At the end of the experiment the rats were weighed and blood samples were collected. Finally, the rats were euthanized and then the liver, small intestine, spleen, kidneys, heart, brain, lung, testes and leg muscles were removed and weighed. In the blood of Cu-0 rats the lower Cp activity and greater GPx and CAT activity than in Cu-6.5 rats were noticed. In the liver, lungs, heart and testes of Cu-0 rats, a decreased content of Cu were noticed. Application of Cu-0 diets resulted in increased LOOH level in the small intestine, liver, and heart, as well as increased MDA content in the liver, spleen, lungs, brain and testes. The Cu-0 treatment caused a decrease in SOD activity in the heart, lungs and testes of the rats and a decrease in CAT activity in the small intestine. In the brain and testes of rats from the Cu-0 treatment, lower content of GSH + GSSG was observed. The brain of rats from the Cu-0 treatment showed an increase in the level of PCs, 8-OHdG, Casp 8 and DNA methylation. The research has shown that a deficiency of Cu in the diet impairs the body’s antioxidant defences, which in turn leads to increased lipid oxidation in the liver, small intestinal wall, heart, spleen, lungs, brain and testes, as well as to oxidation of proteins and DNA in the brain. A deficiency of Cu in the diet also increases methylation of cytosine in the brain.

Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement

DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.

Epalrestat improves motor symptoms by reducing oxidative stress and inflammation in the reserpine induced mouse model of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting a large number of elderly people worldwide. The current therapies for PD are symptom-based; they do not provide a cure but improve the quality of life. Muscular dysfunction is the hallmark clinical feature of PD and oxidative stress and inflammation play a critical role in its pathogenesis. Epalrestat is used for the treatment of diabetic neuropathy and is known to improve antioxidative defense mechanisms in the CNS. Therefore, in this study, we investigated the role of Epalrestat in the reserpine induced mouse model of PD.

METHOD

We used Swiss Albino mice for the PD model and tested for akinesia/bradykinesia, muscular rigidity, palpebral ptosis, and tremor, as well as conducting swim and open field tests. Brain samples were used to determine oxidative stress parameters and infiltration of immune cells.

RESULTS

Epalrestat treatment significantly improved akinesia and bradykinesia, muscular dysfunctions, tremor level, and gait functions compared to the reserpine group. It also improved the latency in the swim test. Eplarestat significantly reduced lipid peroxidation and NO concentration in different brain tissues and increased the activity of antioxidative enzymes, glutathione, catalase, and superoxide dismutase. Furthermore, Epalrestat reduced neuroinflammation by reducing the number of infiltrating immune cells.

CONCLUSION

Eplarestat improves muscular dysfunction in PD by reducing oxidative stress and inflammation.

N-acetyl Cysteine Administration Is Associated With Increased Cerebral Glucose Metabolism in Patients With Multiple Sclerosis: An Exploratory Study

Background: Multiple Sclerosis (MS) is an autoimmune disease marked by progressive neurocognitive injury. Treatment options affording neuroprotective effects remain largely experimental. The purpose of this proof of concept study was to explore the effects of N-acetyl-cysteine (NAC) on cerebral glucose metabolism (CMRGlu) and symptoms in patients with multiple sclerosis (MS).

Methods: Twenty-four patients with MS were randomized to either NAC plus standard of care, or standard of care only (waitlist control). The experimental group received NAC intravenously once per week and orally the other 6 days. Patients in both groups were evaluated at baseline and after 2 months (of receiving the NAC or waitlist control period) with an integrated Position Emission Tomography (PET)/ Magnetic Resonance Imaging (MRI) scanner, using 18F Fluorodeoxyglucose (FDG) to measure cerebral glucose metabolism. Following imaging evaluation at 2 months, subjects initially attributed to the standard of care arm were eligible for treatment with NAC. Clinical and symptom questionnaires were also completed initially and after 2 months.

Results: The FDG PET data showed significantly increased cerebral glucose metabolism in several brain regions including the caudate, inferior frontal gyrus, lateral temporal gyrus, and middle temporal gyrus (p < 0.05) in the MS group treated with NAC, as compared to the control group. Self-reported scores related to cognition and attention were also significantly improved in the NAC group as compared to the control group.

Conclusions: The results of this study suggest that NAC positively affects cerebral glucose metabolism in MS patients, which is associated with qualitative, patient reported improvements in cognition and attention. Larger scale studies may help to determine the clinical impact of NAC on measures of functioning over the course of illness, as well as the most effective dosage and dosage regimen.

Antioxidant Alternatives in the Treatment of Amyotrophic Lateral Sclerosis: A Comprehensive Review

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that produces a selective loss of the motor neurons of the spinal cord, brain stem and motor cortex. Oxidative stress (OS) associated with mitochondrial dysfunction and the deterioration of the electron transport chain has been shown to be a factor that contributes to neurodegeneration and plays a potential role in the pathogenesis of ALS. The regions of the central nervous system affected have high levels of reactive oxygen species (ROS) and reduced antioxidant defenses. Scientific studies propose treatment with antioxidants to combat the characteristic OS and the regeneration of nicotinamide adenine dinucleotide (NAD+) levels by the use of precursors. This review examines the possible roles of nicotinamide riboside and pterostilbene as therapeutic strategies in ALS.

Minireview on the Relations between Gut Microflora and Parkinson's Disease: Further Biochemical (Oxidative Stress), Inflammatory, and Neurological Particularities

The aetiology of Parkinson's disease (PD) is a highly debated topic. Despite the progressive increase in the number of patients diagnosed with PD over the last couple of decades, the causes remain largely unknown. This report is aimed at highlighting the main features of the microbial communities which have been termed "the second brain" that may be a major participant in the etiopathophysiology of PD. It is possible that dysbiosis could be caused by an overactivity of proinflammatory cytokines which act on the gastrointestinal tract as well as infections. The majority of patients who are diagnosed with PD display gastrointestinal symptoms as one of the earliest features. In addition, an unbalanced cycle of oxidative stress caused by dysbacteriosis may have the effect of gradually promoting PD's specific phenotype. Thus, it seems that bacteria possess the ability to manipulate the brain by initiating specific responses, defining their capability to configure the human body, with oxidative stress playing a pivotal role in preventing infections but also in activating related signalling pathways.

Ferroptosis: past, present and future

Ferroptosis is a new type of cell death that was discovered in recent years and is usually accompanied by a large amount of iron accumulation and lipid peroxidation during the cell death process; the occurrence of ferroptosis is iron-dependent. Ferroptosis-inducing factors can directly or indirectly affect glutathione peroxidase through different pathways, resulting in a decrease in antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in cells, ultimately leading to oxidative cell death. Recent studies have shown that ferroptosis is closely related to the pathophysiological processes of many diseases, such as tumors, nervous system diseases, ischemia-reperfusion injury, kidney injury, and blood diseases. How to intervene in the occurrence and development of related diseases by regulating cell ferroptosis has become a hotspot and focus of etiological research and treatment, but the functional changes and specific molecular mechanisms of ferroptosis still need to be further explored. This paper systematically summarizes the latest progress in ferroptosis research, with a focus on providing references for further understanding of its pathogenesis and for proposing new targets for the treatment of related diseases.

Protective effect of hydrogen sulfide on oxidative stress-induced neurodegenerative diseases

Hydrogen sulfide is an antioxidant molecule that has a wide range of biological effects against oxidative stress. Balanced oxidative stress is also vital for maintaining cellular function in biological system, where reactive oxygen species are the main source of oxidative stress. When the normal redox balance is disturbed, deoxyribonucleic acid, lipid, and protein molecules are oxidized under pathological conditions, like diabetes mellitus that leads to diabetic peripheral neuropathy. In diabetes mellitus-induced diabetic peripheral neuropathy, due to hyperglycemia, pancreatic beta cell (β cell) shows resistance to insulin secretion. As a consequence, glucose metabolism is disturbed in neuronal cells which are distracted from providing proper cell signaling pathway. Not only diabetic peripheral neuropathy but also other central damages occur in brain neuropathy. Neurological studies regarding type 1 diabetes mellitus patients with Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis have shown changes in the central nervous system because high blood glucose levels (HbA1c) appeared with poor cognitive function. Oxidative stress plays a role in inhibiting insulin signaling that is necessary for brain function. Hydrogen sulfide exhibits antioxidant effects against oxidative stress, where cystathionine β synthase, cystathionine γ lyase, and 3-mercaptopyruvate sulfurtransferase are the endogenous sources of hydrogen sulfide. This review is to explore the pathogenesis of diabetes mellitus-induced diabetic peripheral neuropathy and other neurological comorbid disorders under the oxidative stress condition and the anti-oxidative effects of hydrogen sulfide.

Density Functional Theory Study of Antioxidant Adsorption onto Single- Wall Boron Nitride Nanotubes: Design of New Antioxidant Delivery Systems

Background:

Boron Nitride Nanotubes (BNNTs) have recently emerged as an interesting field of study, because they could be used for the realization of developed, integrated and compact nanostructures to be formulated. BNNTs with similar surface morphology, alternating B and N atoms completely substitute for C atoms in a graphitic-like sheet with nearly no alterations in atomic spacing, with uniformity in dispersion in the solution, and readily applicable in biomedical applications with no obvious toxicity. Also demonstrating a good cell interaction and cell targeting.

Aim and Objective:

With a purpose of increasing the field of BNNT for drug delivery, a theoretical investigation of the interaction of Melatonin, Vitamin C, Glutathione and lipoic acid antioxidants using (9, 0) zigzag BNNTs is shown using density functional theory.

Methods:

The geometries corresponding to Melatonin, Vitamin C, Glutathione and lipoic acid and BNNT with different lengths were individually optimized with the DMOL3 program at the LDA/ DNP (fine) level of theory.

Results:

In the presence of external electric field Melatonin, Vitamin C, Glutathione and lipoic acid could be absorbed considerably on BNNT with lengths 22 and 29 Å, as the adsorption energy values in the presence of external electric field are considerably increased.

Conclusion:

The external electric field is an appropriate technique for adsorbing and storing antioxidants on BNNTs. Moreover, it is believed that applying the external electric field may be a proper method for controlling release rate of drugs.

Targeting NRF2 for the Treatment of Friedreich's Ataxia: A Comparison among Drugs

NRF2 (Nuclear factor Erythroid 2-related Factor 2) signaling is impaired in Friedreich's Ataxia (FRDA), an autosomal recessive disease characterized by progressive nervous system damage and degeneration of nerve fibers in the spinal cord and peripheral nerves. The loss of frataxin in patients results in iron sulfur cluster deficiency and iron accumulation in the mitochondria, making FRDA a fatal and debilitating condition. There are no currently approved therapies for the treatment of FRDA and molecules able to activate NRF2 have the potential to induce clinical benefits in patients. In this study, we compared the efficacy of six redox-active drugs, some already adopted in clinical trials, targeting NRF2 activation and frataxin expression in fibroblasts obtained from skin biopsies of FRDA patients. All of these drugs consistently increased NRF2 expression, but differential profiles of NRF2 downstream genes were activated. The Sulforaphane and N-acetylcysteine were particularly effective on genes involved in preventing inflammation and maintaining glutathione homeostasis, the dimethyl fumarate, omaxevolone, and EPI-743 in counteracting toxic products accumulation, the idebenone in mitochondrial protection. This study may contribute to develop synergic therapies, based on a combination of treatment molecules.

Anthocyanins and Their Metabolites as Therapeutic Agents for Neurodegenerative Disease

Neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis (ALS), are characterized by the death of neurons within specific regions of the brain or spinal cord. While the etiology of many neurodegenerative diseases remains elusive, several factors are thought to contribute to the neurodegenerative process, such as oxidative and nitrosative stress, excitotoxicity, endoplasmic reticulum stress, protein aggregation, and neuroinflammation. These processes culminate in the death of vulnerable neuronal populations, which manifests symptomatically as cognitive and/or motor impairments. Until recently, most treatments for these disorders have targeted single aspects of disease pathology; however, this strategy has proved largely ineffective, and focus has now turned towards therapeutics which target multiple aspects underlying neurodegeneration. Anthocyanins are unique flavonoid compounds that have been shown to modulate several of the factors contributing to neuronal death, and interest in their use as therapeutics for neurodegeneration has grown in recent years. Additionally, due to observations that the bioavailability of anthocyanins is low relative to that of their metabolites, it has been proposed that anthocyanin metabolites may play a significant part in mediating the beneficial effects of an anthocyanin-rich diet. Thus, in this review, we will explore the evidence evaluating the neuroprotective and therapeutic potential of anthocyanins and their common metabolites for treating neurodegenerative diseases.

Glutathione Transferase P1-1 an Enzyme Useful in Biomedicine and as Biomarker in Clinical Practice and in Environmental Pollution

Glutathione transferase P1-1 (GSTP1-1) is expressed in some human tissues and is abundant in mammalian erythrocytes (here termed e-GST). This enzyme is able to detoxify the cell from endogenous and exogenous toxic compounds by using glutathione (GSH) or by acting as a ligandin. This review collects studies that propose GSTP1-1 as a useful biomarker in different fields of application. The most relevant studies are focused on GSTP1-1 as a biosensor to detect blood toxicity in patients affected by kidney diseases. In fact, this detoxifying enzyme is over-expressed in erythrocytes when unusual amounts of toxins are present in the body. Here we review articles concerning the level of GST in chronic kidney disease patients, in maintenance hemodialysis patients and to assess dialysis adequacy. GST is also over-expressed in autoimmune disease like scleroderma, and in kidney transplant patients and it may be used to check the efficiency of transplanted kidneys. The involvement of GSTP in the oxidative stress and in other human pathologies like cancer, liver and neurodegenerative diseases, and psychiatric disorders is also reported. Promising applications of e-GST discussed in the present review are its use for monitoring human subjects living in polluted areas and mammals for veterinary purpose.

Systemic L-Buthionine -S-R-Sulfoximine Treatment Increases Plasma NGF and Upregulates L-cys/L-cys2 Transporter and γ-Glutamylcysteine Ligase mRNAs Through the NGF/TrkA/Akt/Nrf2 Pathway in the Striatum

Glutathione (GSH) is the most abundant intracellular antioxidant. GSH depletion leads to oxidative stress and neuronal damage in the central nervous system (CNS). In mice, the acute systemic inhibition of GSH synthesis by L-buthionine-S-R-sulfoximine (BSO) triggers a protective response and a subsequent increase in the CNS GSH content. This response might be modulated by a peripheral increment of circulating nerve growth factor (NGF). NGF is an important activator of antioxidant pathways mediated by tropomyosin-related kinase receptor A (TrkA). Here, we report that peripheral administration of BSO increased plasma NGF levels. Additionally, BSO increased NGF levels and activated the NGF/TrkA/Akt pathway in striatal neurons. Moreover, the response in the striatum included an increased transcription of nrf2, gclm, lat1, eaac1, and xct, all of which are involved in antioxidant responses, and L-cys/L-cys₂ and glutamate transporters. Using antibody against NGF confirmed that peripheral NGF activated the NGF/TrkA/Akt/Nrf2 pathway in the striatum and subsequently increased the transcription of gclm, nrf2, lat1, eaac1, and xct. These results provide evidence that the reduction of peripheral GSH pools increases peripheral NGF circulation that orchestrates a neuroprotective response in the CNS, at least in the striatum, through the NGF/TrkA/Akt/Nrf2 pathway.

Evaluation of neuroprotective activity of digoxin and semisynthetic derivatives against partial chemical ischemia

Recently, cardiotonic steroids (CTS) have been shown to lead to the activation of Na,K-ATPase at low concentrations in brain, promoting neuroprotection against ischemia. We report here the results of the use of digoxin and its semisynthetic derivatives BD-14, BD-15, and BD-16 against partial chemical ischemic induction followed by reperfusion in murine neuroblastoma cells neuro-2a (N2a). For chemical ischemic induction, sodium azide (5 mM) was used for 5 hours, and then reperfusion was induced for 24 hours. Na,K-ATPase activity and protein levels were analyzed in membrane preparation of N2a cells pretreated with the compounds (150 nM), in the controls and in induced chemical ischemia. In the Na,K-ATPase activity and protein levels assays, the steroids digoxin and BD-15 demonstrated a capacity to modulate the activity of the enzyme directly, increasing its levels of expression and activity. Oxidative parameters, such as superoxide dismutase (SOD) activity, lipid peroxidation (thiobarbituric acid reactive substance), glutathione peroxidase (GPx), glutathione (GSH) levels, hydrogen peroxide content, and the amount of free radicals (reactive oxygen species) during induced chemical ischemia were also evaluated. Regarding the redox state, lipid peroxidation, hydrogen peroxide content, and GPx activity, we have observed an increase in the chemical ischemic group, and a reduction in the groups treated with CTS. SOD activity increased in all treated groups when compared to control and GSH levels decreased when treated with sodium azide and did not change with CTS treatments. Regarding the lipid profile, we saw a decrease in the content of phospholipids and cholesterol in the chemical ischemic group, and an increase in the groups treated with CTS. In conclusion, the compounds used in this study demonstrate promising results, since they appear to promote neuroprotection in cells exposed to chemical ischemia.

Pathomechanisms of Blood-Brain Barrier Disruption in ALS

The blood-brain barrier (BBB) and the blood-spinal cord barrier (BSCB) are responsible for controlling the microenvironment within neural tissues in humans. These barriers are fundamental to all neurological processes as they provide the extreme nutritional demands of neural tissue, remove wastes, and maintain immune privileged status. Being a semipermeable membrane, both the BBB and BSCB allow the diffusion of certain molecules, whilst restricting others. In amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases, these barriers become hyperpermeable, allowing a wider variety of molecules to pass through leading to more severe and more rapidly progressing disease. The intention of this review is to discuss evidence that BBB hyperpermeability is potentially a disease driving feature in ALS and other neurodegenerative diseases. The various biochemical, physiological, and genomic factors that can influence BBB permeability in ALS and other neurodegenerative diseases are also discussed, in addition to novel therapeutic strategies centred upon the BBB.

Salivary Redox Biomarkers in Different Stages of Dementia Severity

This study is the first to evaluate oxidative stress biomarkers in saliva/blood of patients with varying degrees of dementia progression. The study included 50 healthy controls and 50 dementia patients divided into two groups: those with mild and moderate dementia (MMSE 11–23) and patients suffering from severe dementia (MMSE 0–10). Cognitive functions of the subjects were assessed using the Mini Mental State Examination (MMSE). Enzymatic and non-enzymatic antioxidants, oxidative damage products and protein glycoxidative modifications were determined in non-stimulated (NWS) and stimulated (SWS) saliva as well as erythrocyte/plasma samples. Generally, in dementia patients, we observed the depletion of antioxidant defences leading to oxidative and glycoxidative damage in NWS, SWS and blood samples. Both salivary and blood oxidative stress increased with the severity of the disease, and correlated with a decrease of cognitive functions. Interestingly, in dementia patients, reduced glutathione (GSH) in NWS correlated not only with the severity of dementia, but also with GSH concentration in the plasma. In receiver operating characteristic (ROC) analysis, we have demonstrated that salivary GSH clearly distinguishes patients with severe dementia from those suffering from mild or moderate dementia (area under the curve (AUC) = 1). Therefore, salivary GSH can be used as a non-invasive biomarker of cognitive impairment.

Role of mitochondria in diabetic peripheral neuropathy: Influencing the NAD+-dependent SIRT1-PGC-1α-TFAM pathway

Survival of human peripheral nervous system neurons and associated distal axons is highly dependent on energy. Diabetes invokes a maladaptation in glucose and lipid energy metabolism in adult sensory neurons, axons and Schwann cells. Mitochondrial (Mt) dysfunction has been implicated as an etiological factor in failure of energy homeostasis that results in a low intrinsic aerobic capacity within the neuron. Over time, this energy failure can lead to neuronal and axonal degeneration and results in increased oxidative injury in the neuron and axon. One of the key pathways that is impaired in diabetic peripheral neuropathy (DPN) is the energy sensing pathway comprising the nicotinamide-adenine dinucleotide (NAD⁺)-dependent Sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor-γ coactivator α (PGC-1α)/Mt transcription factor A (TFAM or mtTFA) signaling pathway. Knockout of PGC-1α exacerbates DPN, whereas overexpression of human TFAM is protective. LY379268, a selective metabolomic glutamate receptor 2/3 (mGluR2/3) receptor agonist, also upregulates the SIRT1/PGC-1α/TFAM signaling pathway and prevents DPN through glutamate recycling in Schwann/satellite glial (SG) cells and by improving dorsal root ganglion (DRG) neuronal Mt function. Furthermore, administration of nicotinamide riboside (NR), a precursor of NAD⁺, prevents and reverses DPN, in part by increasing NAD⁺ levels and SIRT1 activity. In summary, we review the role of NAD⁺, mitochondria and the SIRT1-PGC-1α-TFAM pathway both from the perspective of pathogenesis and therapy in DPN.

Boosting GSH Using the Co-Drug Approach: I-152, a Conjugate of N-acetyl-cysteine and β-mercaptoethylamine

Glutathione (GSH) has poor pharmacokinetic properties; thus, several derivatives and biosynthetic precursors have been proposed as GSH-boosting drugs. I-152 is a conjugate of N-acetyl-cysteine (NAC) and S-acetyl-β-mercaptoethylamine (SMEA) designed to release the parent drugs (i.e., NAC and β-mercaptoethylamine or cysteamine, MEA). NAC is a precursor of L-cysteine, while MEA is an aminothiol able to increase GSH content; thus, I-152 represents the very first attempt to combine two pro-GSH molecules. In this review, the in-vitro and in-vivo metabolism, pro-GSH activity and antiviral and immunomodulatory properties of I-152 are discussed. Under physiological GSH conditions, low I-152 doses increase cellular GSH content; by contrast, high doses cause GSH depletion but yield a high content of NAC, MEA and I-152, which can be used to resynthesize GSH. Preliminary in-vivo studies suggest that the molecule reaches mouse organs, including the brain, where its metabolites, NAC and MEA, are detected. In cell cultures, I-152 replenishes experimentally depleted GSH levels. Moreover, administration of I-152 to C57BL/6 mice infected with the retroviral complex LP-BM5 is effective in contrasting virus-induced GSH depletion, exerting at the same time antiviral and immunomodulatory functions. I-152 acts as a pro-GSH agent; however, GSH derivatives and NAC cannot completely replicate its effects. The co-delivery of different thiol species may lead to unpredictable outcomes, which warrant further investigation.

Cancer-associated mutation and beyond: The emerging biology of isocitrate dehydrogenases in human disease

Isocitrate dehydrogenases (IDHs) are critical metabolic enzymes that catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (αKG), NAD(P)H, and CO₂. IDHs epigenetically control gene expression through effects on αKG-dependent dioxygenases, maintain redox balance and promote anaplerosis by providing cells with NADPH and precursor substrates for macromolecular synthesis, and regulate respiration and energy production through generation of NADH. Cancer-associated mutations in IDH1 and IDH2 represent one of the most comprehensively studied mechanisms of IDH pathogenic effect. Mutant enzymes produce (R)-2-hydroxyglutarate, which in turn inhibits αKG-dependent dioxygenase function, resulting in a global hypermethylation phenotype, increased tumor cell multipotency, and malignancy. Recent studies identified wild-type IDHs as critical regulators of normal organ physiology and, when transcriptionally induced or down-regulated, as contributing to cancer and neurodegeneration, respectively. We describe how mutant and wild-type enzymes contribute on molecular levels to disease pathogenesis, and discuss efforts to pharmacologically target IDH-controlled metabolic rewiring.

Critical Roles of Glutaredoxin in Brain Cells-Implications for Parkinson's Disease

SIGNIFICANCE

Glutaredoxin (Grx)1, an evolutionarily conserved and ubiquitous enzyme, regulates redox signal transduction and protein redox homeostasis by catalyzing reversible S-glutathionylation. Grx1 plays different roles in different cell types. In Parkinson's disease (PD), Grx1 regulates apoptosis signaling in dopaminergic neurons, so that loss of Grx1 leads to increased cell death; in microglial cells, Grx1 regulates proinflammatory signaling, so that upregulation of Grx1 promotes cytokine production. Here we examine the regulatory roles of Grx1 in PD with a view toward therapeutic innovation. Recent Advances: In postmortem midbrain PD samples, Grx1 was decreased relative to controls, specifically within dopaminergic neurons. In Caenorhabditis elegans models of PD, loss of the Grx1 homologue led to exacerbation of the neurodegenerative phenotype. This effect was partially relieved by overexpression of neuroprotective DJ-1, consistent with regulation of DJ-1 content by Grx1. Increased GLRX copy number in PD patients was associated with earlier PD onset; and Grx1 levels correlated with levels of proinflammatory tumor necrosis factor-α in mouse and human brain samples. In vitro studies showed Grx1 to be upregulated on proinflammatory activation of microglia. Direct overexpression of Grx1 increased microglial activation; silencing Grx1 diminished activation. Grx1 upregulation in microglia corresponded to increased neuronal cell death in coculture. Overall, these studies identify competing roles of Grx1 in PD etiology.

CRITICAL ISSUES

The dilemma regarding Grx1 as a PD therapeutic target is whether to stimulate its upregulation for neuroprotection or inhibit its proinflammatory activity.

FUTURE DIRECTIONS

Further investigation is needed to understand the preponderant role of Grx1 regarding dopaminergic neuronal survival.

Effect of Majun Baladur on life span, climbing ability, oxidative stress and dopaminergic neurons in the transgenic Drosophila model of Parkinson's disease

The effect of a poly herbal drug Majun Baladur (MB) was studied on the transgenic Drosophila melanogaster expressing human alpha synuclein in the neurons (PD flies). The equivalents of recommended dose for human were established for 20 g of fly food i.e. 0.0014, 0.0028, 0.0042 and 0.0056 g per 20 g of diet. The PD flies were allowed to feed on it for 24 days before performing the assays. The exposure to MB increased the life span and improves the activity of PD flies. The PD flies exposed to 0.0014, 0.0028, 0.042 and 0.0056 g of MB showed a dose dependent significant delay of 1.47, 1.88, 2.52 and 3.05 folds in the climbing ability compared to unexposed PD flies. A dose dependent significant decrease of 1.38, 1.45, 1.48 and 1.65 folds in TBARS; 1.08, 1.11, 1.17 and 1.20 folds in the GST activity; 1.20, 1.28, 1.39 and 1.52 folds in the PC content; 1.43, 1.53, 1.65 and 1.79 folds in the Caspase-9 activity; 1.21, 1.31, 1.53 and 1.64 folds in the activity of Caspase-3 and 1.24, 1.42, 1.50 and 1.79 folds in the activity of catalase; 1.50, 1.63, 1.88 and 2.06 folds in the activity of SOD in PD flies exposed to 0.0014, 0.0028, 0.042 and 0.0056 g of MB, respectively. A significant dose dependent increase of 1.20, 1.29, 1.33 and 1.44 folds in as NPSH content was observed in PD flies exposed to 0.0014, 0.0028, 0.042 and 0.0056 g of MB, respectively. The exposure to MB protects the loss of dopaminergic neurons as is evident by immunohistochemistry. It is concluded that MB is potent in reducing the PD symptoms being mimicked in the transgenic flies.

Effects of vitamin E supplementation on the risk and progression of AD: a systematic review and meta-analysis

Objective: The association between vitamin E supplementation and Alzheimer's disease (AD) was controversial because of conflicting data in the literature. This study was designed to systematically evaluate evidence about the efficacy of vitamin E supplementation not only on the risk but also on the progression of AD. Design: Five electronic databases were searched for studies published up to June 2017. Articles reporting vitamin E supplementation and AD were included, and the random-effect model was performed for the meta-analysis about the relationship between vitamin E supplementation and AD. Results: Five cohort studies and three randomized controlled trial (RCT) studies (total n = 14,262) involving 1313 cases about vitamin E effects on the risk of AD and 244 cases about effects on progression of AD. The pooled RR for vitamin E supplemental and risk of AD was 0.81 [95% CI: 0.50-1.33, I ² = 69.2%]. Suitable data could not be extracted to do meta-analysis as there was no unified standard of outcome measure for studies on AD progression. We carefully analyzed and evaluated the authenticity and accuracy of every single trial, while reliable evidence could not be obtained. Conclusions: From what we do, neither the synthetic data on risk of AD nor the critical review on progression of AD could provide enough evidence on our research. Thus, we cannot draw a specific conclusion on the association or correlation between Vitamin E and AD.

The development of the concept of ferroptosis

The term ferroptosis was coined in 2012 to describe an iron-dependent regulated form of cell death caused by the accumulation of lipid-based reactive oxygen species; this type of cell death was found to have molecular characteristics distinct from other forms of regulated cell death. Features of ferroptosis have been observed periodically over the last several decades, but these molecular features were not recognized as evidence of a distinct form of cell death until recently. Here, we describe the history of observations consistent with the current definition of ferroptosis, as well as the advances that contributed to the emergence of the concept of ferroptosis. We also discuss recent implications and applications of manipulations of the ferroptotic death pathway.

Insulin Resistance and Oxidative Stress in the Brain: What's New?

The latest studies have indicated a strong relationship between systemic insulin resistance (IR) and higher incidence of neurodegeneration, dementia, and mild cognitive impairment. Although some of these abnormalities could be explained by chronic hyperglycaemia, hyperinsulinemia, dyslipidaemia, and/or prolonged whole-body inflammation, the key role is attributed to the neuronal redox imbalance and oxidative damage. In this mini review, we provide a schematic overview of intracellular oxidative stress and mitochondrial abnormalities in the IR brain. We highlight important correlations found so far between brain oxidative stress, ceramide generation, β-amyloid accumulation, as well as neuronal apoptosis in the IR conditions.

The Emerging Roles of Ferroptosis in Huntington's Disease

Huntington's disease (HD) is an autosomal dominant and fatal neurodegenerative disorder, which is caused by an abnormal CAG repeat in the huntingtin gene. Despite its well-defined genetic origin, the molecular mechanisms of neuronal death are unclear yet, thus there are no effective strategies to block or postpone the process of HD. Ferroptosis, a recently identified iron-dependent cell death, attracts considerable attention due to its putative involvement in neurodegenerative diseases. Accumulative data suggest that ferroptosis is very likely to participate in HD, and inhibition of the molecules and signaling pathways involved in ferroptosis can significantly eliminate the symptoms and pathology of HD. This review first describes evidence for the close relevance of ferroptosis and HD in patients and mouse models, then summarizes advances for the mechanisms of ferroptosis involved in HD, finally outlines some therapeutic strategies targeted ferroptosis. Comprehensive understanding of the emerging roles of ferroptosis in the occurrence of HD will help us to explore effective therapies for slowing the progression of this disease.

The roles of S-nitrosylation and S-glutathionylation in Alzheimer's disease

Alzheimer's disease (AD) is a debilitating dementia with complex pathophysiological alterations including modifications to endogenous cysteine. S-nitrosylation (SNO) is a well-studied posttranslational modification (PTM) in the context of AD while S-glutathionylation (PSSG) remains less studied. Excess reactive oxygen and reactive nitrogen species (ROS/RNS) directly or indirectly generate SNO and PSSG. SNO is dysregulated in AD and plays a pervasive role in processes such as protein function, cell signaling, metabolism, and apoptosis. Despite some studies into the role of SNO in AD, multiple identified SNO proteins lack deep investigation and SNO modifications outside of brain tissues are limited, leaving the full role of SNO in AD to be elucidated. PSSG homeostasis is perturbed in AD and may affect a myriad of cellular processes. Here we overview the role of nitric oxide (NO) in AD, discuss proteomic methodologies to investigate SNO and PSSG, and review SNO and PSSG in AD. A more thorough understanding of SNO, PSSG, and other cysteinyl PTMs in AD will be helpful for the development of novel therapeutics against neurodegenerative diseases.

Ukgansan protects dopaminergic neurons from 6-hydroxydopamine neurotoxicity via activation of the nuclear factor (erythroid-derived 2)-like 2 factor signaling pathway

The sustenance of redox homeostasis in brain is the crucial factor to treat Parkinson's disease (PD). Nuclear factor (erythroid-derived 2)-like 2 factor (Nrf2)-mediated antioxidant response is well known for the main cellular endogenous defense mechanisms against oxidative stress. This study investigated for the first time the effects and possible mechanisms of action of Ukgansan on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in both in vitro and in vivo models of PD. We investigated the protective effect of Ukgansan against 6-OHDA with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. In addition, we demonstrated that Ukgansan significantly increased the expression of antioxidant response elements (ARE) and pro-survival protein as Bcl2 and suppressed the expression of pro-apoptotic factors, such as Bax, cytochrome c, and caspase-3 using immunoblotting. For the in vivo study, we used a mouse model of PD involving stereotaxic injection of 6-OHDA into the striatum (ST). Ukgansan alleviated motor dysfunctions induced by 6-OHDA followed by pole, open-field, and rotation tests. Dopaminergic neuronal loss and Nrf2 activation were evaluated by immunohistochemistry in the mouse ST and substantia nigra pars compacta (SNpc) regions. Ukgansan significantly protected dopaminergic neurons from 6-OHDA toxicity in mouse ST and SNpc by activating Nrf2. These results indicate that Ukgansan inhibited 6-OHDA-induced dopaminergic neuronal cell damage via activation of Nrf2 and its related factors in 6-OHDA-induced dopaminergic loss in vitro and in vivo. Thus, Ukgansan might delay the progression of PD via maintenance of redox homeostasis.

Ferroptosis and Its Role in Diverse Brain Diseases

Ferroptosis is a recently identified, iron-regulated, non-apoptotic form of cell death. It is characterized by cellular accumulation of lipid reactive oxygen species that ultimately leads to oxidative stress and cell death. Although first identified in cancer cells, ferroptosis has been shown to have significant implications in several neurologic diseases, such as ischemic and hemorrhagic stroke, Alzheimer's disease, and Parkinson's disease. This review summarizes current research on ferroptosis, its underlying mechanisms, and its role in the progression of different neurologic diseases. Understanding the role of ferroptosis could provide valuable information regarding treatment and prevention of these devastating diseases.

Effects of propofol and isoflurane on excitatory amino acid carrier 1 mRNA and glutathione protein levels in rat hippocampus

OBJECTIVE

We compared the effects of two anesthetics, isoflurane and propofol, on the nuclear or cytosolic localization of nuclear factor erythroid 2-related factor 2 (Nrf2), mRNA expression levels of excitatory amino acid carrier 1 (EAAC1), and glutathione (GSH) protein levels in the rat hippocampus.

METHODS

Fifty-two adult male Sprague-Dawley rats were randomly divided into three groups: a control group, a group that received propofol for 240 minutes (P240), and a group that received isoflurane for 240 minutes (I240). We compared GSH protein and EAAC1 mRNA expression levels in the rat hippocampus and evaluated Nrf2 content in cytosolic and nuclear fractions in the three groups.

RESULTS

GSH protein and EAAC1 mRNA expression levels were significantly higher in the I240 and P240 groups compared with the control group. The I240 and P240 groups showed lower Nrf2 protein levels in the cytosolic fractions, but higher levels in the nuclear fractions compared with the control group.

CONCLUSION

Treatment with isoflurane or propofol may enhance GSH production by facilitating translocation of Nrf2 into the nucleus and increasing EAAC1mRNA expression in the rat hippocampus. Isoflurane and propofol show similar profiles in EAAC1 expression-associated GSH production.

Biothiols and oxidative stress markers and polymorphisms of TOMM40 and APOC1 genes in Alzheimer's disease patients

Alzheimer’s disease (AD) is a progressive disease, with frequently observed improper biothiols turnover, homocysteine (Hcy) and glutathione (GSH). GSH protects cells from oxidative stress and may be determined by 8-oxo-2’-deoxyguanosine (8-oxo2dG) level and its repair enzyme 8-oxoguanine DNA glycosylase (OGG1). The presence of unfavorable alleles, e.g., in APOE cluster, TOMM40 or APOC1 is known to facilitate the dementia onset under oxidative stress.

The aim of the study was to analyze rs1052452, rs2075650 TOMM40 polymorphisms, rs4420638 APOC1, and their correlation with Hcy, GSH, 8-oxo2dG, OGG1 levels in plasma of AD patients and controls.

We recruited 230 individuals: 88 AD, 80 controls without (UC), 62 controls with (RC) positive family history of AD. The TOMM40 genotype was determined by HRM and capillary electrophoresis, while APOC1 by HRM. The concentrations of OGG1, 8-oxo2dG were determined by ELISA, whereas Hcy, GSH by HPLC/EC.

We showed that over 60% of AD patients had increased Hcy levels (p<0.01 vs. UC, p<0.001 vs. RC), while GSH (p<0.01 vs. UC), 8-oxo2dG (p<0.01 vs. UC, p<0.001 vs. RC) were reduced. Minor variants: rs10524523-L, rs4420638-G, rs2075650-G were significantly overrepresented in AD. For rs4420638-G, rs2075650-G variants, the association remained significant in APOE E4 non-carriers. The misbalance of analyzed biothiols, and 8-oxo2dG, OGG1 were more pronounced in carriers of major variants: rs10524523-S/VL, rs4420638-A, rs2075650-A.

We showed, for the first time, that APOC1 and TOMM40 rs2075650 polymorphisms may be independent risk factors of developing AD, whose major variants are accompanied by disruption of biothiols metabolism and inefficient removal of DNA oxidation.

Cellular Redox Imbalance and Neurochemical Effect in Cognitive-Deficient Old Rats

The purpose of the present study is to access the linkage between dysregulation of glutamatergic neurotransmission, oxidative metabolism, and serine signaling in age-related cognitive decline. In this work, we evaluated the effect of natural aging in rats on the cognitive abilities for hippocampal-dependent tasks. Oxidative metabolism indicators are glutathione (GSH), malondialdehyde (MDA) concentrations, and cytosolic phospholipase A₂ (PLA₂) activity. In addition, neurotransmitter amino acid (L-Glutamic acid, γ-aminobutyric acid (GABA), DL-Serine and DL-Aspartic acid) concentrations were studied in brain areas such as the frontal cortex (FC) and hippocampus (HPC). The spatial long-term memory revealed significant differences among experimental groups: the aged rats showed an increase in escape latency to the platform associated with a reduction of crossings and spent less time on the target quadrant than young rats. Glutathione levels decreased for analyzed brain areas linked with a significant increase in MDA concentrations and PLA₂ activity in cognitive-deficient old rats. We found glutamate levels only increased in the HPC, whereas a reduced level of serine was found in both regions of interest in cognitive-deficient old rats. We demonstrated that age-related changes in redox metabolism contributed with alterations in synaptic signaling and cognitive impairment.

Systemic L-buthionine-S-R-sulfoximine administration modulates glutathione homeostasis via NGF/TrkA and mTOR signaling in the cerebellum

Glutathione (GSH) is an essential component of intracellular antioxidant systems that plays a primordial role in the protection of cells against oxidative stress, maintaining redox homeostasis and xenobiotic detoxification. GSH synthesis in the brain is limited by the availability of cysteine and glutamate. Cystine, the disulfide form of cysteine is transported into endothelial cells of the blood-brain barrier (BBB) and astrocytes via the system x_c^-, which is composed of xCT and the heavy chain of 4F2 cell surface antigen (4F2hc). Cystine is reduced inside the cells and the L-type amino acid transporter 1 (LAT1) transports cysteine from the endothelial cells into the brain, cysteine is transported into the neurons through the excitatory amino acid transporter 3 (EAAT3), also known as excitatory amino acid carrier 1 (EAAC1). The mechanistic/mammalian target of rapamycin (mTOR) and neurotrophins can activate signaling pathways that modulate amino acid transporters for GSH synthesis. The present study found that systemic L-buthionine-S-R-sulfoximine (BSO) administration selectively altered GSH homeostasis and EAAT3 levels in the mice cerebellum. Intraperitoneal treatment of mice with 6 mmol/kg of BSO depleted GSH and GSSG in the liver at 2 h of treatment. The cerebellum, but not other brain regions, exhibited a redox response. The mTOR and the neuronal growth factor (NGF)/tropomyosin receptor kinase A (TrkA) signaling pathways were activated and lead to an increase in the protein levels of the EAAT3 transporter, which was linked to an increase in the GSH/GSSG ratio and GSH concentration in the cerebellum at 0.5 and 2 h, respectively. Therefore, the cerebellum responds to peripheral GSH depletion via activation of the mTOR and NGF/TrkA pathways, which increase the transport of cysteine for GSH synthesis.

Ouabain attenuates oxidative stress and modulates lipid composition in hippocampus of rats in lipopolysaccharide-induced hypocampal neuroinflammation in rats

Our study aimed to analyze the effect of ouabain (OUA) administration on lipopolysaccharide (LPS)-induced changes in hippocampus of rats. Oxidative parameters were analyzed in Wistar rats after intraperitoneal injection of OUA (1.8 µg/kg), LPS (200 µg/kg), or OUA plus LPS or saline. To reach our goal, activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), in addition to levels of reduced glutathione (GSH), protein carbonyl (PCO) and lipid peroxidation (LPO) were evaluated. We also analyzed the membrane lipid profile and some important lipids for the nervous system, such as phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidic acid and sphingomyelin. The group that received only LPS showed increased oxidative stress, as evidenced by an increase in LPO (about twice), PCO (about three times) levels, and CAT activity (80%). Conversely, administration of LPS decreased GSH levels (55%), and GPx activity (30%), besides a reduction in the amount of PI (60%) and PC (45%). By other side, OUA alone increased the amount of PI (45%), PE (85%), and PC (70%). All harmful effects recorded were attenuated by OUA, suggesting a protective effect against LPS-induced oxidative stress. The relevance of our results extends beyond changes in oxidative parameters induced by LPS, because nanomolar doses of OUA may be useful in neurodegenerative models. Other studies on other cardenolides and substances related issues, as well as the development of new molecules derived from OUA, could also be useful in general oxidative and/or cellular stress, a condition favoring the appearance of neuronal pathologies.

French and Mediterranean-style diets: Contradictions, misconceptions and scientific facts-A review

The determination of appropriate dietary strategies for the prevention of chronic degenerative diseases, cancer, diabetes, and cardiovascular diseases remains a challenging and highly relevant issue worldwide. Epidemiological dietary interventions have been studied for decades with contrasting impacts on human health. Moreover, research scientists and physicians have long debated diets encouraging alcohol intake, such as the Mediterranean and French-style diets, with regard to their impact on human health. Understanding the effects of these diets may help to improve in the treatment and prevention of diseases. However, further studies are warranted to determine which individual food components, or combinations thereof, have a beneficial impact on different diseases, since a large number of different compounds may occur in a single food, and their fate in vivo is difficult to measure. Most explanations for the positive effects of Mediterranean-style diet, and of the French paradox, have focused largely on the beneficial properties of antioxidants, among other compounds/metabolites, in foods and red wine. Wine is a traditional alcoholic beverage that has been associated with both healthy and harmful effects. Not withstanding some doubts, there is reasonable unanimity among researchers as to the beneficial effects of moderate wine consumption on cardiovascular disease, diabetes, osteoporosis, and longevity, which have been ascribed to polyphenolic compounds present in wine. Despite this, conflicting findings regarding the impact of alcohol consumption on human health, and contradictory findings concerning the effects of non-alcoholic wine components such as resveratrol, have led to confusion among consumers. In addition to these contradictions and misconceptions, there is a paucity of human research studies confirming known positive effects of polyphenols in vivo. Furthermore, studies balancing both known and unknown prognostic factors have mostly been conducted in vitro or using animal models. Moreover, current studies have shifted focus from red wine to dairy products, such as cheese, to explain the French paradox. The aim of this review is to highlight the contradictions, misconceptions, and scientific facts about wines and diets, giving special focus to the Mediterranean and French diets in disease prevention and human health improvement. To answer the multiplicity of questions regarding the effects of diet and specific diet components on health, and to relieve consumer uncertainty and promote health, comprehensive cross-demographic studies using the latest technologies, which include foodomics and integrated omics approaches, are warranted.

Biological Significance of the Suppression of Oxidative Phosphorylation in Induced Pluripotent Stem Cells

We discovered that induced pluripotent stem cell (iPSC) clones generated from aged tissue donors (A-iPSCs) fail to suppress oxidative phosphorylation. Compared to embryonic stem cells (ESCs) and iPSCs generated from young donors (Y-iPSCs), A-iPSCs show poor expression of the pluripotent stem cell-specific glucose transporter 3 (GLUT3) and impaired glucose uptake, making them unable to support the high glucose demands of glycolysis. Persistent oxidative phosphorylation in A-iPSCs generates higher levels of reactive oxygen species (ROS), which leads to excessive elevation of glutathione (a ROS-scavenging metabolite) and a blunted DNA damage response. These phenotypes were recapitulated in Y-iPSCs by inhibiting pyruvate dehydrogenase kinase (PDK) or supplying citrate to activate oxidative phosphorylation. In addition, oxidative phosphorylation in A-iPSC clones depletes citrate, a nuclear source of acetyl group donors for histone acetylation; this consequently alters histone acetylation status. Expression of GLUT3 in A-iPSCs recovers the metabolic defect, DNA damage response, and histone acetylation status.

Potentiating effect of imidacloprid on arsenic-induced testicular toxicity in Wistar rats

BACKGROUND

It is an established fact that humans and animals are exposed to more than one chemical concurrently from various sources such as food, air and water. In the past, much emphasis was laid on evaluating the toxic effects of a single chemical. Nowadays an increased attention is being paid to the interaction of xenobiotics with one another. Therefore, a study was aimed to evaluate the potentiating effect of imidacloprid (IMI) on arsenic-induced testicular toxicity in rats.

METHODS

Adult male Wistar rats randomly divided into eight groups with six in each were subjected to daily oral administrations for 28 days. Group I served as control, group II received IMI at the dose rate of 16.9 mg/kg body weight, group III, IV and V received arsenic at the dose rate of 50, 100 and 150 ppb in drinking water whereas group VI, VII and VIII received both arsenic and IMI.

RESULTS

Repeated oral administrations of IMI or arsenic (150 ppb) alone resulted in a significant (P < 0.05) elevation in the levels of malondialdehyde (MDA) and advanced oxidation protein product (AOPP) along with significant (P < 0.05) decline in total thiols and antioxidant enzymatic activities indicating reduced antioxidant defense in testicular tissue of exposed rats. These findings were further corroborated with histological alterations in testes like fluid accumulation in interstitial spaces in IMI administered rats. Similarly, rats provided access exclusively to arsenic-containing drinking water induced degenerative changes in seminiferous tubules in a concentration-dependent manner. Concurrent administration of IMI and arsenic produced more severe antioxidant and histopathological alterations of testes as compared to exposure to either toxicant.

CONCLUSIONS

Reduced antioxidant activities, increased MDA and AOPP levels with severe histopathological alterations in testes of rats on concurrent exposure indicated that IMI potentiated the arsenic-induced testicular toxicity in Wistar rats.

Toxic effects of imidacloprid combined with arsenic: Oxidative stress in rat liver

Imidacloprid (IMI), a newer neonicotinoid insecticide, induces oxidative insult to hepatocytes due to the formation of reactive metabolites during hepatic metabolism. The present study aimed to determine the potentiating effect of arsenic (As) on IMI-induced hepatic damage in Wistar rats. Rats, randomly divided into eight groups with six in each, were subjected to daily oral administration for 28 days. Group I served as control; group II received IMI at the dose rate of 16.9 mg/kg body weight; groups III, IV, and V received As at the dose rate of 50, 100, and 150 ppb, respectively, in drinking water; groups VI, VII, and VIII received both IMI (16.9 mg/kg) and As in drinking water at the rate of 50, 100, and 150 ppb, respectively. Repeated oral administration of IMI or As resulted in significant ( p < 0.05) elevation of plasma phosphatases, transferases, hepatic malondialdehyde, and advanced oxidation protein product levels, but significantly ( p < 0.05) decreased levels of total proteins, thiols, and activities of antioxidant enzymes that indicate oxidation-induced hepatotoxicity. These findings were further corroborated by histological alterations in hepatic tissue of IMI or As-administered rats. The coadministration of both IMI and As in rats produced more severe alterations in these parameters in hepatic tissue. Reduced antioxidant indices and increased hepatic damage biomarkers with pronounced histopathological alterations in hepatic tissue after combined exposure to toxicants indicate potentiating toxic effect of As on IMI-induced hepatotoxicity.

Impact of Drosophila Models in the Study and Treatment of Friedreich's Ataxia

Drosophila melanogaster has been for over a century the model of choice of several neurobiologists to decipher the formation and development of the nervous system as well as to mirror the pathophysiological conditions of many human neurodegenerative diseases. The rare disease Friedreich’s ataxia (FRDA) is not an exception. Since the isolation of the responsible gene more than two decades ago, the analysis of the fly orthologue has proven to be an excellent avenue to understand the development and progression of the disease, to unravel pivotal mechanisms underpinning the pathology and to identify genes and molecules that might well be either disease biomarkers or promising targets for therapeutic interventions. In this review, we aim to summarize the collection of findings provided by the Drosophila models but also to go one step beyond and propose the implications of these discoveries for the study and cure of this disorder. We will present the physiological, cellular and molecular phenotypes described in the fly, highlighting those that have given insight into the pathology and we will show how the ability of Drosophila to perform genetic and pharmacological screens has provided valuable information that is not easily within reach of other cellular or mammalian models.

Effect of Genistein on the Transgenic Drosophila Model of Parkinson's Disease

Parkinson's disease (PD) is the second-most common neurodegenerative disorder and is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta. Oxidative stress has also been linked with the progression of PD, hence the involvement of a natural plant product could offer neuroprotection. The present study deals with the effect of genistein on the transgenic flies expressing normal human alpha synuclein panneurally. The PD flies were exposed to 10, 20, 30, and 40 µM of genistein (mixed in diet) for 24 days. A significant dose-dependent increase in the life span and delay in the loss of climbing ability were observed in the PD flies exposed to genistein (p < .05). A significant dose-dependent decrease in oxidative stress markers and increase in dopamine content were observed in PD flies exposed to genistein. However, the exposure of genistein did not inhibit the expression of α-synuclein in the brains of PD flies.

Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia

Mitochondrial homeostasis is essential for maintaining healthy cellular function and survival. The detrimental involvement of mitochondrial dysfunction in neuro-degenerative diseases has recently been highlighted in human conditions, such as Parkinson's, Alzheimer's and Huntington's disease. Friedreich's ataxia (FA) is another neuro-degenerative, but also cardio-degenerative condition, where mitochondrial dysfunction plays a crucial role in disease progression. Deficient expression of the mitochondrial protein, frataxin, is the primary cause of FA, which leads to adverse alterations in whole cell and mitochondrial iron metabolism. Dys-regulation of iron metabolism in these compartments, results in the accumulation of inorganic iron deposits in the mitochondrial matrix that is thought to potentiate oxidative damage observed in FA. Therefore, the maintenance of mitochondrial homeostasis is crucial in the progression of neuro-degenerative conditions, particularly in FA. In this review, vital mitochondrial homeostatic processes and their roles in FA pathogenesis will be discussed. These include mitochondrial iron processing, mitochondrial dynamics (fusion and fission processes), mitophagy, mitochondrial biogenesis, mitochondrial energy production and calcium metabolism.