Riluzole-triggered GSH synthesis via activation of glutamate transporters to antagonize methylmercury-induced oxidative stress in rat cerebral cortex

Novel HOCl-Responsive Theranostic Prodrug for the Early Diagnosis and Therapy of Ischemic Stroke

In this work, a hypochlorous acid (HOCl)-responsive prodrug MB-R for diagnosis and therapy of ischemic stroke (IS) was constructed using the near-infrared fluorophore methylene blue linked to riluzole by the urea bond. MB-R exhibits good biocompatibility, fast response (<1 min), and high selectivity toward HOCl. MB-R was successfully utilized to visualize the HOCl levels, as well as the distribution of HOCl in the brains of IS mice to determine the progression of the disease. Meanwhile, the treatment with MB-R could reduce the cerebral infarction volume and improve the motor function in IS mice. Most importantly, MB-R could be utilized in the treatment of stroke through antioxidant, anti-inflammatory, and neuroprotective effects, further suggesting that riluzole was a potentially therapeutic agent for IS. Thus, this work paves the way for the development of intelligent theranostic agent for the early diagnosis and treatment of IS.

Therapeutic targeting of the oxidative stress generated by pathological molecular pathways in the neurodegenerative diseases, ALS and Huntington's

Neurodegenerative disorders are characterized by a progressive decline of specific neuronal populations in the brain and spinal cord, typically containing aggregates of one or more proteins. They can result in behavioral alterations, memory loss and a decline in cognitive and motor abilities. Various pathways and mechanisms have been outlined for the potential treatment of these diseases, where redox regulation is considered as one of the most common druggable targets. For example, in amyotrophic lateral sclerosis (ALS) with superoxide dismutase-1 (SOD1) pathology, there is a downregulation of the antioxidant response nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. TDP-43 proteinopathy in ALS is associated with elevated levels of reactive oxygen species and mitochondrial dyshomeostasis. In ALS with mutant FUS, poly ADP ribose polymerase-dependent X ray repair cross complementing 1/DNA-ligase recruitment to the sites of oxidative DNA damage is affected, thereby causing defects in DNA damage repair. Oxidative stress in Huntington's disease (HD) with mutant huntingtin accumulation manifests as protein oxidation, metabolic energetics dysfunction, metal ion dyshomeostasis, DNA damage and mitochondrial dysfunction. The impact of oxidative stress in the progression of these diseases further warrants studies into the role of antioxidants in their treatment. While an antioxidant, edaravone, has been approved for therapeutics of ALS, numerous antioxidant molecules failed to pass the clinical trials despite promising initial studies. In this review, we summarize the oxidative stress pathways and redox modulators that are investigated in ALS and HD using various models.

Functional groups effect on the toxicity of modified ZIF-90 to Photobacterium phosphoreum

Zeolitic imidazolate framework (ZIF) is of wide interest in biomedical applications due to its extraordinary properties such as high storage capacity, functionality and favorable biocompatibility. However, more comprehensive safety assessments are still essential before ZIF is broadly used in biomedicine. Using the characteristic that aldehyde groups on the surface of ZIF-90 can be modified with other functional groups, a series of ZIF-90s modified with different functional groups (oxime group, carboxyl group, amino group and sulfhydryl group) were synthesized to investigate the effect of functionalization on the toxicity of ZIF-90. ZIF-90 series showed concentration-dependent toxic effects on Photobacterium phosphoreum T3 and the functionalized ZIF-90s are more toxic than pristine ZIF-90, with the ZIF-90 modified with amino group (ZIF-90-NH2) showing the strongest toxicity (IC50 = 23.06 mg/L). Based on the results of the cellular assay and stability exploration, we concluded that corresponding imidazole-ligand release and the property of positively charged are responsible for the elevated toxicity of ZIF-90-NH2. Cell membrane damage, oxidative damage and luminescence damage are the main contributors to the toxic effects of ZIF-90 series. This study explored the effect of surface functionalization on the toxicity of ZIF and proposed mechanistic clues for the safety application of ZIF.

Mitochondria, a Key Target in Amyotrophic Lateral Sclerosis Pathogenesis

Mitochondrial dysfunction occurs in numerous neurodegenerative diseases, particularly amyotrophic lateral sclerosis (ALS), where it contributes to motor neuron (MN) death. Of all the factors involved in ALS, mitochondria have been considered as a major player, as secondary mitochondrial dysfunction has been found in various models and patients. Abnormal mitochondrial morphology, defects in mitochondrial dynamics, altered activities of respiratory chain enzymes and increased production of reactive oxygen species have been described. Moreover, the identification of CHCHD10 variants in ALS patients was the first genetic evidence that a mitochondrial defect may be a primary cause of MN damage and directly links mitochondrial dysfunction to the pathogenesis of ALS. In this review, we focus on the role of mitochondria in ALS and highlight the pathogenic variants of ALS genes associated with impaired mitochondrial functions. The multiple pathways demonstrated in ALS pathogenesis suggest that all converge to a common endpoint leading to MN loss. This may explain the disappointing results obtained with treatments targeting a single pathological process. Fighting against mitochondrial dysfunction appears to be a promising avenue for developing combined therapies in the future.

Oxidative Stress and Antioxidants in Neurodegenerative Disorders

Neurodegenerative disorders constitute a substantial proportion of neurological diseases with significant public health importance. The pathophysiology of neurodegenerative diseases is characterized by a complex interplay of various general and disease-specific factors that lead to the end point of neuronal degeneration and loss, and the eventual clinical manifestations. Oxidative stress is the result of an imbalance between pro-oxidant species and antioxidant systems, characterized by an elevation in the levels of reactive oxygen and reactive nitrogen species, and a reduction in the levels of endogenous antioxidants. Recent studies have increasingly highlighted oxidative stress and associated mitochondrial dysfunction to be important players in the pathophysiologic processes involved in neurodegenerative conditions. In this article, we review the current knowledge of the general effects of oxidative stress on the central nervous system, the different specific routes by which oxidative stress influences the pathophysiologic processes involved in Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis and Huntington's disease, and how oxidative stress may be therapeutically reversed/mitigated in order to stall the pathological progression of these neurodegenerative disorders to bring about clinical benefits.

Boosting Mitochondrial Potential: An Imperative Therapeutic Intervention in Amyotrophic Lateral Sclerosis

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a progressive and terminal neurodegenerative disorder. Mitochondrial dysfunction, imbalance of cellular bioenergetics, electron chain transportation and calcium homeostasis are deeply associated with the progression of this disease. Impaired mitochondrial functions are crucial in rapid neurodegeneration. The mitochondria of ALS patients are associated with deregulated Ca2+ homeostasis and elevated levels of reactive oxygen species (ROS), leading to oxidative stress. Overload of mitochondrial calcium and ROS production leads to glutamatereceptor mediated neurotoxicity. This implies mitochondria are an attractive therapeutic target.

OBJECTIVE

The aim of this review is to brief the latest developments in the understanding of mitochondrial pathogenesis in ALS and emphasize the restorative capacity of therapeutic candidates.

RESULTS

In ALS, mitochondrial dysfunction is a well-known phenomenon. Various therapies targeted towards mitochondrial dysfunction aim at decreasing ROS generation, increasing mitochondrial biogenesis, and inhibiting apoptotic pathways. Some of the therapies briefed in this review may be categorized as synthetic, natural compounds, genetic materials, and cellular therapies.

CONCLUSION

The overarching goals of mitochondrial therapies in ALS are to benefit ALS patients by slowing down the disease progression and prolonging overall survival. Despite various therapeutic approaches, there are many hurdles in the development of a successful therapy due to the multifaceted nature of mitochondrial dysfunction and ALS progression. Intensive research is required to precisely elucidate the molecular pathways involved in the progression of mitochondrial dysfunctions that ultimately lead to ALS. Because of the multifactorial nature of ALS, a combination therapy approach may hold the key to cure and treat ALS in the future.

Methylmercury promotes oxidative stress and autophagy in rat cerebral cortex: Involvement of PI3K/AKT/mTOR or AMPK/TSC2/mTOR pathways and attenuation by N-acetyl-L-cysteine

Methylmercury (MeHg) is a potent neurotoxicant that could induce oxidative stress and autophagy. However, the underlying mechanisms through which MeHg affects the central nervous system have not been fully elucidated, and little has been known of the interaction between oxidative stress and autophagy. Therefore, rats were administrated with different MeHg concentrations to evaluate the neurotoxic effects and autophagy in cerebral cortex. Moreover, we have investigated the neuroprotective role of N-acetyl-L-cysteine (NAC) against MeHg-induced neurotoxicity in order to estimate the regulation effects of oxidative stress on autophagy. A total of 64 rats, 40 of which were randomly divided into control and MeHg-treated (4, 8 and 12 μ mol/kg) groups. The remaining 24 rats were divided into control, NAC control (1 mmol/kg), 12 μ mol/kg MeHg, and NAC pretreatment. Administration of 12 μ mol/kg MeHg significantly increased behavioral and pathological abnormalities, and autophagy levels. In addition, the oxidative stress levels increased, together with abnormal expression of autophagy-related molecules. Pretreatment with NAC significantly prevented MeHg-induced oxidative stress and PI3K/AKT/mTOR or AMPK/TSC2/mTOR-mediated autophagy. In conclusion, the present study suggested that oxidative stress can regulate autophagy through PI3K/AKT/mTOR or AMPK/TSC2/mTOR pathways. This study provides a theoretical basis for the study and treatment of MeHg-induced neurotoxicity.

Alleviation of nicotine-induced reproductive disorder, clastogenicity, and histopathological alterations by fenugreek saponin bulk and nanoparticles in male rats

Nicotine is the most abundant ingredient in cigarette smoking and has serious side effects on the lung, heart, reproductive system, and many other human organs. Saponins extracted from many plants exhibit multiple biological actions such as anti-cancer effects. Therefore, the possible protective effect of fenugreek saponin (FS) and nanofenugreek saponin (NFS) against nicotine-induced toxicity in male rats was investigated in this study. Animals were divided into a control group and the nicotine (1.5 mg/kg/day), FS (25, 50, and 100 mg/kg/day), or/and NFS (20, 40, and 80 mg/kg/day) administered groups. Micronucleus assay, histopathological, and sperm abnormality examinations as well as measurement of the acetylcholinesterase (AChE) gene expression were conducted. Our findings revealed that nicotine treatment induced significant increases in the incidence of micronucleus, sperm abnormalities, and expression levels of AChE in addition to inducing histopathological changes in rat testis. On the other hand, administration of FS or NFS with nicotine significantly decreased the incidence of micronuclei and the percentage of sperm abnormalities as well as the expression levels of AChE gene. Moreover, nicotine-induced histological alterations were reduced by given FS or NFS with nicotine. In conclusion, nicotine-induced sperm abnormalities, chromosomal damage, and histological injuries were mitigated by administration of FS or NFS with nicotine, and thus, FS and NFS could be used as ameliorating agents against nicotine toxicity.

Pharmacological prevention of renal ischemia-reperfusion injury in a rat model

INTRODUCTION

Renal ischemia-reperfusion injury (IRI) can lead to significant morbidity and mortality. It remains a leading cause of acute kidney injury and is therefore an important issue in trauma and renal transplant surgery. Various pharmaceutical agents have been used in an attempt to dampen the harmful effects of IRI but few have been shown to be useful clinically. Riluzole, Lidocaine and Lamotrigine have been demonstrated to show anti-ischaemic properties in other organs; however, their use has not been tested in the kidneys. We investigated Riluzole, Lidocaine and Lamotrigine for their preventive effects of renal IRI using a rat model.

METHODS

Winstar rats (n = 48) were divided into four groups (n = 12 per group)-three treatment groups and one control group. Riluzole, Lidocaine and Lamotrigine were given prior to renal ischemia only (IO) or IRI. The degree of ischemia was measured by glutathione levels and a TUNEL assay was used to measure DNA fragmentation.

RESULTS

Riluzole, Lidocaine and Lamotrigine pre-treatment each resulted in statistically higher glutathione levels compared to controls (P = 0.002; P = 0.007 and P = 0.005, respectively). Riluzole and Lidocaine were also effective at preventing depletion of glutathione following IO (P = 0.007 and P = 0.014 respectively), while Lamotrigine was ineffective in IO (P = 0.71). The degree of DNA fragmentation seen on the TUNEL assay was markedly reduced in all three-drug groups in both IO and IRI.

DISCUSSION

Riluzole, Lidocaine and Lamotrigine all have anti-ischaemic effects in the rat kidney and can have potential therapeutic implications.

Melatonin Blocks Morphine-Induced Place Preference: Involvement of GLT-1, NF-κB, BDNF, and CREB in the Nucleus Accumbens

Opioid addiction remains a widespread issue despite continuous attempts by the FDA to help maintain abstinence. Melatonin is a neurohormone considered to be involved only in the neuroendocrine and reproductive systems; however, recent reports have demonstrated its potential to attenuate drug addiction and dependence. Cumulative studies have suggested that melatonin can attenuate the rewarding effects of several drugs of abuse, including opioids. This study aimed to investigate the effect of melatonin (50 mg/kg) on morphine (5 mg/kg) to produce place preference. We also investigated the effect of melatonin and morphine on the expression of GLT-1, BDNF, NF-κB, and CREB within the nucleus accumbens. Male Wistar rats were divided into control, morphine, melatonin, and the morphine + melatonin groups. The study involved a two-phase habituation phase from day 1 to day 3 and an acquisition phase from day 5 to day 14. The conditioned place preference (CPP) score, distance traveled, resting time, ambulatory count, and total activity count were measured for all animals. Rats that received morphine showed a significant increase in CPP score compared to those in the control group. Morphine treatment reduced the mRNA expression of GLT-1, BDNF, and CREB and increased that of NF-κB. However, melatonin treatment administered 30 min before morphine treatment attenuated morphine place preference and reversed GLT-1, BDNF, NF-κB, and CREB expression levels. In conclusion, the study results indicate, for the first time, the new potential targets of melatonin in modulating morphine-induced CPP.

Melatonin antagonizes ozone-exacerbated asthma by inhibiting the TRPV1 channel and stabilizing the Nrf2 pathway

Over the past few years, ozone has been identified as a potential risk factor for exacerbating asthma. However, few attempts have been made to prevent the progression of ozone-exacerbated asthma. This study investigated the attenuating effects of melatonin on ozone-aggravated allergic asthma, and explored the changes to the transient receptor potential vanilloid 1 (TRPV1)-nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway associated with melatonin treatment. The levels of TRPV1 and calcitonin gene-related peptides (CGRP) in lung tissue were detected by immunohistochemistry, western blot, and enzyme-linked immunosorbent assay (ELISA). The Nrf2 signaling involved proteins and mRNA were evaluated by western blot and RT-qPCR. The change of Immunoglobulin E (IgE) and T helper (Th) 2 and Th17 cytokines in serum and bronchoalveolar lavage fluid (BALF) was determined by ELISA. Recruitment of inflammatory cells in BALF, histopathological changes, and airway hyperresponsiveness (AHR) were also determined in lung tissues. Our results indicated that melatonin treatment significantly reduced oxidative stress, as indicated by levels of glutathione (GSH), malonaldehyde (MDA), and 8-hydroxy-2-deoxyguanosine (8-OH-dG). Moreover, ozone-exacerbated asthma symptoms, such as inflammatory cell infiltration, levels of serum immunoglobulin, Th2 and Th17 cytokines in BALF, obvious changes in lung histology, and AHR, were all ameliorated by melatonin treatment. Interestingly, melatonin not only markedly decreased the protein levels of TRPV1 and CGRP, but also enhanced the expression of Nrf2, quinone oxidoreductase-1 (NQO-1), and heme oxygenase-1 (HO-1). Taken together, our results demonstrate that melatonin administration could antagonize ozone-exacerbated asthma by inhibiting the TRPV1 channel and stabilizing the Nrf2 pathway.

Differential Effects of Human P301L Tau Expression in Young versus Aged Mice

The greatest risk factor for developing Alzheimer’s disease (AD) is increasing age. Understanding the changes that occur in aging that make an aged brain more susceptible to developing AD could result in novel therapeutic targets. In order to better understand these changes, the current study utilized mice harboring a regulatable mutant P301L human tau transgene (rTg(TauP301L)4510), in which P301L tau expression can be turned off or on by the addition or removal of doxycycline in the drinking water. This regulatable expression allowed for assessment of aging independent of prolonged mutant tau expression. Our results suggest that P301L expression in aged mice enhances memory deficits in the Morris water maze task. These behavioral changes may be due to enhanced late-stage tau pathology, as evidenced by immunoblotting and exacerbated hippocampal dysregulation of glutamate release and uptake measured by the microelectrode array technique. We additionally observed changes in proteins important for the regulation of glutamate and tau phosphorylation that may mediate these age-related changes. Thus, age and P301L tau interact to exacerbate tau-induced detrimental alterations in aged animals.

The Antioxidant Efficacy of Wheatgrass (Triticum Aestivum) on Mercuric Chloride (HgCl2) - Induced Oxidative Stress in Rat Model

Mercury is a harmful toxic pollutant, which has hepato-nephrotoxic, hematotoxic, genotoxic and neurotoxic, effects. The aim of the study was to evaluate the protective efficacy of wheatgrass on mercuric chloride (HgCl2) induced oxidative stress and associated complications in rat model. Albino rats were divided into four groups (three rats per group). Group I normal control group. Group II oxidative stressed group received mercuric chloride (0.5 mg/kg/day). Group III only received wheatgrass extract (100 mg/kg/day), whereas Group IV received wheatgrass (100 mg/kg/day) after one hour, followed by mercuric chloride (0.5 mg/kg/day) for 30 days. The results of the study showed that wheatgrass supplementation significantly decreased the HgCl2 induced elevated oxidative stress parameters Plasma Malondialdehyde (MDA) content, Plasma membrane redox system (PMRS), Advanced oxidation protein products (AOPP), simultaneously elevated lipid profile (Total Cholesterol, Triglycerides, Low-density lipoprotein (LDL), liver enzymes as, Plasma Alkaline phosphatase (ALP), Aspartate aminotransferase (AST), and Alanine aminotransferase (ALT), Serum Urea, and Creatinine levels in rats. In addition, wheatgrass treatment improved the antioxidant status in terms of intracellular Reduced Glutathione (GSH), Ferric reducing antioxidant power (FRAP) and 2, 2- diphenyl -1- picrylhydrazyl (DPPH). Therefore it can be concluded that wheatgrass has great potential to diminish the stress-mediated complications and improve the antioxidant status.

The Interplay of RNA Binding Proteins, Oxidative Stress and Mitochondrial Dysfunction in ALS

RNA binding proteins fulfil a wide number of roles in gene expression. Multiple mechanisms of RNA binding protein dysregulation have been implicated in the pathomechanisms of several neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Oxidative stress and mitochondrial dysfunction also play important roles in these diseases. In this review, we highlight the mechanistic interplay between RNA binding protein dysregulation, oxidative stress and mitochondrial dysfunction in ALS. We also discuss different potential therapeutic strategies targeting these pathways.

TBHQ-Overview of Multiple Mechanisms against Oxidative Stress for Attenuating Methamphetamine-Induced Neurotoxicity

Methamphetamine is a derivative of amphetamines, a highly addictive central stimulant with multiple systemic toxicity including the brain, heart, liver, lung, and spleen. It has adverse effects such as apoptosis and breakdown of the blood-brain barrier. Methamphetamine is a fatal and toxic chemical substance, and its lethal mechanism has been widely studied in recent years. The possible mechanism is that methamphetamine can cause cardiotoxicity and neurotoxicity mainly by inducing oxidative stress so as to generate heat, eliminate people's hunger and thirst, and maintain a state of excitement so that people can continue to exercise. According to many research, there is no doubt that methamphetamine triggers neurotoxicity by inducing reactive oxygen species (ROS) production and redox imbalance. This review summarized the mechanisms of methamphetamine-induced neurotoxicity including apoptosis and blood-brain barrier breakdown through oxidative stress and analyzed several possible antioxidative mechanisms of tert-butylhydroquinone (TBHQ) which is a kind of food additive with antioxidative effects. As a nuclear factor E2-related factor 2 (Nrf2) agonist, TBHQ may inhibit neurotoxicity caused by oxidative stress through the following three mechanisms: the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system, the astrocytes activation, and the glutathione pathway. The mechanism about methamphetamine's toxic effects and its antioxidative therapeutic drugs would become a research hotspot in this field and has very important research significance.

Oxidative Stress in Amyotrophic Lateral Sclerosis: Pathophysiology and Opportunities for Pharmacological Intervention

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease or Charcot disease, is a fatal neurodegenerative disease that affects motor neurons (MNs) and leads to death within 2–5 years of diagnosis, without any effective therapy available. Although the pathological mechanisms leading to ALS are still unknown, a wealth of evidence indicates that an excessive reactive oxygen species (ROS) production associated with an inefficient antioxidant defense represents an important pathological feature in ALS. Substantial evidence indicates that oxidative stress (OS) is implicated in the loss of MNs and in mitochondrial dysfunction, contributing decisively to neurodegeneration in ALS. Although the modulation of OS represents a promising approach to protect MNs from degeneration, the fact that several antioxidants with beneficial effects in animal models failed to show any therapeutic benefit in patients raises several questions that should be analyzed. Using specific queries for literature search on PubMed, we review here the role of OS-related mechanisms in ALS, including the involvement of altered mitochondrial function with repercussions in neurodegeneration. We also describe antioxidant compounds that have been mostly tested in preclinical and clinical trials of ALS, also describing their respective mechanisms of action. While the description of OS mechanism in the different mutations identified in ALS has as principal objective to clarify the contribution of OS in ALS, the description of positive and negative outcomes for each antioxidant is aimed at paving the way for novel opportunities for intervention. In conclusion, although antioxidant strategies represent a very promising approach to slow the progression of the disease, it is of utmost need to invest on the characterization of OS profiles representative of each subtype of patient, in order to develop personalized therapies, allowing to understand the characteristics of antioxidants that have beneficial effects on different subtypes of patients.

Free L-glutamate-induced modulation in oxidative and neurochemical profile contributes to enhancement in locomotor and memory performance in male rats

Glutamate (Glu), the key excitatory neurotransmitter in the central nervous system, is considered essential for brain functioning and has a vital role in learning and memory formation. Earlier it was considered as a harmful agent but later found to be useful for many body functions. However, studies regarding the effects of free l-Glu administration on CNS function are limited. Therefore, current experiment is aimed to monitor the neurobiological effects of free l-Glu in male rats. l-Glu was orally administered to rats for 5-weeks and changes in behavioral performance were monitored. Thereafter, brain and hippocampus were collected for oxidative and neurochemical analysis. Results showed that chronic supplementation of free l-Glu enhanced locomotor performance and cognitive function of animals which may be attributed to the improved antioxidant status and cholinergic, monoaminergic and glutamatergic neurotransmission in brain and hippocampus. Current results showed that chronic supplementation of l-Glu affects the animal behaviour and brain functioning via improving the neurochemical and redox system of brain. Free l-Glu could be a useful therapeutic agent to combat neurological disturbances however this requires further targeted studies.

Altered Mitochondrial Dynamics in Motor Neuron Disease: An Emerging Perspective

Mitochondria plays privotal role in diverse pathways that regulate cellular function and survival, and have emerged as a prime focus in aging and age-associated motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Accumulating evidence suggests that many amyloidogenic proteins, including MND-associated RNA/DNA-binding proteins fused in sarcoma (FUS) and TAR DNA binding protein (TDP)-43, are strongly linked to mitochondrial dysfunction. Animal model and patient studies have highlighted changes in mitochondrial structure, plasticity, replication/copy number, mitochondrial DNA instability, and altered membrane potential in several subsets of MNDs, and these observations are consistent with the evidence of increased excitotoxicity, induction of reactive oxygen species, and activation of intrinsic apoptotic pathways. Studies in MND rodent models also indicate that mitochondrial abnormalities begin prior to the clinical and pathological onset of the disease, suggesting a causal role of mitochondrial dysfunction. Our recent studies, which demonstrated the involvement of specific defects in DNA break-ligation mediated by DNA ligase 3 (LIG3) in FUS-associated ALS, raised a key question of its potential implication in mitochondrial DNA transactions because LIG3 is essential for both mitochondrial DNA replication and repair. This question, as well as how wild-type and mutant MND-associated factors affect mitochondria, remain to be elucidated. These new investigation avenues into the mechanistic role of mitochondrial dysfunction in MNDs are critical to identify therapeutic targets to alleviate mitochondrial toxicity and its consequences. In this article, we critically review recent advances in our understanding of mitochondrial dysfunction in diverse subgroups of MNDs and discuss challenges and future directions.

The Potential for Natural Antioxidant Supplementation in the Early Stages of Neurodegenerative Disorders

The neurodegenerative process is characterized by the progressive ultrastructural alterations of selected classes of neurons accompanied by imbalanced cellular homeostasis, a process which culminates, in the later stages, in cell death and the loss of specific neurological functions. Apart from the neuronal cell impairment in selected areas of the central nervous system which characterizes many neurodegenerative diseases (e.g., Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, etc.), some alterations may be found in the early stages including gliosis and the misfolding or unfolding accumulation of proteins. On the other hand, several common pathophysiological mechanisms can be found early in the course of the disease including altered oxidative metabolism, the loss of cross-talk among the cellular organelles and increased neuroinflammation. Thus, antioxidant compounds have been suggested, in recent years, as a potential strategy for preventing or counteracting neuronal cell death and nutraceutical supplementation has been studied in approaching the early phases of neurodegenerative diseases. The present review will deal with the pathophysiological mechanisms underlying the early stages of the neurodegenerative process. In addition, the potential of nutraceutical supplementation in counteracting these diseases will be assessed.

The Effects of Riluzole on Cisplatin-induced Ototoxicity

Introduction  Riluzole (2-amino-6-trifluoromethoxy benzothiazole) is known as a neuroprotective, antioxidant, antiapoptotic agent. It may have beneficial effects on neuronal cell death due to cisplatin-induced ototoxicity.

Objective  To evaluate the effect of riluzole on cisplatin-induced ototoxicity in guinea pigs.

Methods  Twenty-four guinea pigs, studied in three groups, underwent auditory brainstem response evaluation using click and 8 kHz tone burst stimuli. Subsequently, 5 mg/kg of cisplatin were administered to all animals for 3 days intraperitoneally (i.p.) to induce ototoxicity. Half an hour prior to cisplatin, groups 1, 2 and 3 received 2 ml of saline i.p., 6 mg/kg of riluzole hydrochloride i.p., and 8 mg/kg of riluzole hydrochloride i.p., respectively, for 3 days. The auditory brainstem responses were repeated 24 hours after the last drug administration. The cochleae were analyzed by transmission electron microscopy (TEM).

Results  After drug administiration, for 8,000 Hz stimulus, group 1 had significantly higher threshold shifts when compared with groups 2 ( p  < 0.05) and 3 ( p  < 0.05), and there was no significant difference in threshold shifts between groups 2 and 3 ( p  > 0.05). Transmission electron microscopy findings demonstrated the protective effect of riluzole on the hair cells and the stria vascularis, especially in the group treated with 8 mg/kg of riluzole hydrochloride.

Conclusion  We can say that riluzole may have a protective effect on cisplatin- induced ototoxicity. However, additional studies are needed to confirm these results and the mechanisms of action of riluzole.

Di-(2-Ethylhexyl) Phthalate Increases Obesity-Induced Damage to the Male Reproductive System in Mice

OBJECTIVE

This study evaluated the effects of di-(2-ethylhexyl) phthalate (DEHP) and obesity on male reproductive organ function in male mice and the potential mechanism of male secondary hypogonadism (SH) in such mice.

METHODS

140 mice were assigned to six groups for 12 weeks: normal, DEHP, DIO, DIO + DEHP low, DIO + DEHP middle, and DIO + DEHP high. The effects of DEHP and obesity upon the reproductive organs were determined by measuring sperm count and motility, relative testis and epididymis weight, hormone level, and pathological changes. Oxidative stress was evaluated by determining malondialdehyde, T-AOC, SOD, GSH, H2O2, CAT, and GSH-PX in testicular tissues. Nrf2 and Keap1 protein were measured by Western blotting.

RESULTS

DEHP and obesity reduced sperm count and motility, relative testis and epididymis weight, and testosterone level but increased the levels of MDA, H2O2, leptin, and estradiol. Pathological injury was observed in the testicular Leydig cells. Moreover, the activity of CAT, SOD, and GSH-Px enzymes was inhibited. Nrf2 protein expression was reduced but that of Keap1 was increased.

CONCLUSIONS

DEHP and obesity jointly caused damage to male productive function. Oxidative stress in testicular tissue, and a high level of leptin, may provide some evidence to clarify the mechanisms of male SH with DEHP and obesity.

Prophylactic Riluzole Attenuates Oxidative Stress Damage in Spinal Cord Distraction

Spinal cord injury (SCI) without radiographical abnormalities (SCIWORA) presents a significant challenge because of the loss of function despite an apparent normal anatomy. The cause of dysfunction is not understood, and specific treatment options are lacking. Some scoliosis corrective surgeries result in SCIWORA, where stretching of the spinal cord can lead to vascular compromise and hypoxia. The iatrogenic nature of this injury allows for the implantation of neuroprotective strategies that are designed to prevent damage. We utilized a model of atraumatic SCI to evaluate the efficacy of the sodium-channel blocker, riluzole, as a prophylactic neuroprotectant. As expected, the stretch injury caused a significant reduction in intraparenchymal oxygen in distraction (-53.09 ± 22.23%) and riluzole pre-treated distraction animals (-43.04 ± 22.86%). However, in contrast to the oxidative stress and metabolic impairments observed in vehicle-treated distraction animals, in which protein carbonylation increased significantly (5.88 ± 1.3 nmol/mL), riluzole kept these levels within the normal range (1.8 ± 1.0 nmol/mL). This neurprotection also prevented ventral motor neuron hypoplasia and pyknosis, characteristic features of this atraumatic SCI model, and maintained normal gait function (e.g., stride length and stance time). This study provides evidence for the use of prophylactic neuroprotective strategies in which thoracic or spine surgeries present the risk of causing atraumatic SCI.

The role of mitochondria in amyotrophic lateral sclerosis

Mitochondria are unique organelles that are essential for a variety of cellular processes including energy metabolism, calcium homeostasis, lipid biosynthesis, and apoptosis. Mitochondrial dysfunction is a prevalent feature of many neurodegenerative diseases including motor neuron disorders such as amyotrophic lateral sclerosis (ALS). Disruption of mitochondrial structure, dynamics, bioenergetics and calcium buffering has been extensively reported in ALS patients and model systems and has been suggested to be directly involved in disease pathogenesis. Here we review the alterations in mitochondrial parameters in ALS and examine the common pathways to dysfunction.

Protective effects of curcumin against mercury-induced hepatic injuries in rats, involvement of oxidative stress antagonism, and Nrf2-ARE pathway activation

Mercury (Hg) represents a ubiquitous environmental heavy metal that could lead to severe toxic effects in a variety of organs usually at a low level. The present study focused on the liver oxidative stress, one of the most important roles playing in Hg hepatotoxicity, by evaluation of different concentrations of mercuric chloride (HgCl₂) administration. Moreover, the protective potential of curcumin against Hg hepatotoxic effects was also investigated. Eighty-four rats were randomly divided into six groups for a three-days experiment: control, dimethyl sulfoxide control, HgCl₂ treatment (0.6, 1.2, and 2.4 mg kg^-1 day^-1), and curcumin pretreatment (100 mg kg^-1 day^-1) groups. Exposure of HgCl₂ resulted in acute dose-dependent hepatotoxic effects. Administration of 2.4 mg kg^-1 HgCl₂ significantly elevated total Hg, nonprotein sulfhydryl, reactive oxygen species formation, malondialdehyde, apoptosis levels, serum lactate dehydrogenase, and alanine transaminase activities, with an impairment of superoxide dismutase and glutathione peroxidase in the liver. Moreover, HgCl₂ treatment activated nuclear factor-E2-related factor 2-antioxidant response element (Nrf2-ARE) signaling pathway in further investigation, with a significant upregulation of Nrf2, heme oxygenase-1, and γ-glutamylcysteine synthetase heavy subunit expression, relative to control. Pretreatment with curcumin obviously prevented HgCl₂-induced liver oxidative stress, which may be due to its free radical scavenging or Nrf2-ARE pathway-inducing properties. Taking together these data suggest that curcumin counteracts HgCl₂ hepatotoxicity through antagonizing liver oxidative stress.

Riluzole blocks perioperative ischemia-reperfusion injury and enhances postdecompression outcomes in cervical spondylotic myelopathy

Although surgical decompression is considered the gold standard treatment for cervical spondylotic myelopathy (CSM), a proportion of cases show postoperative decline or continue to exhibit substantial neurological dysfunction. To investigate this further, we first examined data from the prospective multicenter AOSpine North America CSM study, finding that 9.3% of patients exhibited postoperative functional decline (ΔmJOA, ≤-1) and that 44% of patients were left with substantial neurological impairment 6 months postoperatively. Notably, 4% of patients experienced perioperative neurological complications within 20 days after surgery in otherwise uneventful surgeries. To shed light on the mechanisms underlying this phenomenon and to test a combination therapeutic strategy for CSM, we performed surgical decompression in a rat model of CSM, randomizing some animals to also receive the U.S. Food and Drug Administration-approved drug riluzole. Spinal cord blood flow measurements increased after decompression surgery in rats. CSM rats showed a transient postoperative neurological decline akin to that seen in some CSM patients, suggesting that ischemia-reperfusion injury may occur after decompression surgery. Riluzole treatment attenuated oxidative DNA damage in the spinal cord and postoperative decline after decompression surgery. Mechanistic in vitro studies also demonstrated that riluzole preserved mitochondrial function and reduced oxidative damage in neurons. Rats receiving combined decompression surgery and riluzole treatment displayed long-term improvements in forelimb function associated with preservation of cervical motor neurons and corticospinal tracts compared to rats treated with decompression surgery alone.

Glutamate release inhibitor, Riluzole, inhibited proliferation of human hepatocellular carcinoma cells by elevated ROS production

Liver cancer is one of the common malignancies in many countries and an increasing cause of cancer death. Despite of that, there are few therapeutic options available with inconsistent outcome, raising a need for developing alternative therapeutic options. Through a drug repositioning screening, we identified and investigated the action mechanism of the Riluzole, an amyotrophic lateral sclerosis (ALS) drug, on hepatocellular carcinoma (HCC) therapy. Treatment of the Riluzole leads to a suppression of cell proliferation in liver primary cancer cells and cancer cell lines. In addition, Riluzole induced caspase-dependent apoptosis and G2/M cell cycle arrest in SNU449 and Huh7 cell lines. In a line with the known function of glutamate release inhibitor, we found Riluzole-treated cells have increased the level of inner cellular glutamate that in turn decrease the glutathione (GSH) level and finally augment the reactive oxygen species (ROS) production. We confirm this finding in vivo by showing the Riluzole-induced GSH and ROS changes in a Huh7 xenograft cancer model. Altogether, these data suggest the anti-cancer effect of Riluzole on hepatocellular carcinoma and the suppression of glutamate signaling might be a new target pathway for HCC therapy.

Enhancement in the Neuroprotective Power of Riluzole Against Cerebral Ischemia Using a Brain Targeted Drug Delivery Vehicle

Riluzole is the only available drug for motor neuron diseases quite well-known for its neuroprotective activity. But its poor aqueous solubility, short half-life with some side-effects at higher concentration poses a limitation to its use as a therapeutic agent. The present study was performed to investigate the therapeutic potential of nanoriluzole (NR), i.e., riluzole encapsulated in nanoparticles against cerebral ischemia (stroke) at three different concentrations [10 (NRL), 20 (NRM), and 40 (NRH) μg/kg body weight intraperitoneally (i.p.)]. Chitosan conjugated NIPAAM (N-isopropylacrylamide) nanoparticles coated with tween80 were synthesized through free radical polymerization. The particles were characterized with Transmission Electron Microscopy, Dynamic Light Scattering, and Fourier Transform Infrared spectroscopy and were found to have size of ∼50 nm. Cerebral ischemia was induced by Middle Cerebral Artery Occlusion (MCAO) model for 1 h and NR was given intraperitoneally after 1 h of MCAO. Animals were dissected after a reperfusion period of 24 h for evaluation of various parameters. Triphenyl tetrazolium chloride staining shows substantial reduction in infarct size in all three treated groups. It was also supported by histopathological results, biochemical parameters, and behavioral studies. Immunological parameters like NOS-2, NF-kB, and COX-2 also show profound reduction in expression in NR treated groups. Thus, the present work clearly demonstrated that the nanoparticle was good enough to carry large amount of drug across the Blood Brain Barrier which results in significant neuroprotection even at a very low concentration. It also substantially lowered the required concentration by overcoming the poor aqueous solubility; hence hardly leaving any scope for side-effects.

Effects of dietary supplementation with glutamate and aspartate on diquat-induced oxidative stress in piglets

This study aimed to investigate the protective effects of dietary glutamate and aspartate supplementations on diquat-induced oxidative stress in piglets. Diquat injection significantly reduced growth performance, including body weight, average daily weight gain, and feed intake (P<0.05). Meanwhile, diquat administration induced oxidative stress evidenced by the decreased serum nitric oxide (NO) and elevated malondialdeyhde (MDA) concentration (P<0.05). Furthermore, diquat-induced oxidative stress disrupted intestinal absorption system and decreased serum threonine, serine, and glycine levels. Dietary supplementation with glutamate improved final body weight, antioxidant system, and expressions of amino acids transporters and enhanced serum glutamate concentration compared with diquat group (P<0.05). While aspartate failed to alleviate diquat-induced oxidative stress, growth depression, and dysfunction of nutrients absorption except for liver relative weight. In conclusion, dietary supplementation with glutamate confers beneficial effects on diquat-induced oxidative stress in piglets, while aspartate exhibits little effects.

Leptin level and oxidative stress contribute to obesity-induced low testosterone in murine testicular tissue

Objective. This study evaluated the effects of obesity on the function of reproductive organs in male mice and the possible mechanism of male secondary hypogonadism (SH) in obesity. Methods. Ninety-six mice were randomly assigned to three groups: the control group, diet-induced obesity group, and diet-induced obesity resistant group for 8 weeks and 19 weeks. The effects of short- and long-term high-fat diet on the reproductive organs were determined by measuring sperm count and motility, relative testis weight, testosterone level, pathological changes and apoptosis of Leydig cells. Oxidative stress was evaluated by determining malondialdehyde, H₂O₂, NO levels, and GSH in testis tissues. CAT, SOD, GSH-Px and Nrf₂ mRNA were measured by real-time PCR. Results. Short- and long-term high-fat diet decreased sperm count and motility, relative testis weight, testosterone level; decreased CAT, SOD, GSH-Px and Nrf₂ mRNA expression; increased MDA, H₂O₂, NO and leptin levels; inhibited the activity of CAT and GSH-Px enzymes. Pathological injury and apoptosis of Leydig cells were found in testis tissue. Conclusions. Pathological damage of Leydig cells, oxidative stress in testis tissue, and high level of leptin may provide some evidence to clarify the mechanisms of male SH in obesity.

Impaired glutathione synthesis in neurodegeneration

Glutathione (GSH) was discovered in yeast cells in 1888. Studies of GSH in mammalian cells before the 1980s focused exclusively on its function for the detoxication of xenobiotics or for drug metabolism in the liver, in which GSH is present at its highest concentration in the body. Increasing evidence has demonstrated other important roles of GSH in the brain, not only for the detoxication of xenobiotics but also for antioxidant defense and the regulation of intracellular redox homeostasis. GSH also regulates cell signaling, protein function, gene expression, and cell differentiation/proliferation in the brain. Clinically, inborn errors in GSH-related enzymes are very rare, but disorders of GSH metabolism are common in major neurodegenerative diseases showing GSH depletion and increased levels of oxidative stress in the brain. GSH depletion would precipitate oxidative damage in the brain, leading to neurodegenerative diseases. This review focuses on the significance of GSH function, the synthesis of GSH and its metabolism, and clinical disorders of GSH metabolism. A potential approach to increase brain GSH levels against neurodegeneration is also discussed.