Edaravone guards dopamine neurons in a rotenone model for Parkinson's disease

Effect of food on oral pharmacokinetics of edaravone coamorphous dispersion containing bile salts as coformers - Part II

OBJECTIVES

Edaravone (EDR) is an effective neuroprotective agent in various neurological diseases; however, its use is restricted due to poor oral absorption. Bile salts are known for improving solubility and inhibiting drug crystallization in supersaturated conditions of the gastrointestinal tract (GIT). In our previous work, we prepared coamorphous dispersion (COAM) of EDR with sodium taurocholate (NaTC) using spray drying. The optimized EDR COAM exhibited superior in vitro performance compared to plain EDR. EDR is well absorbed in fasted-over-fed conditions.

METHODS

The present work, we conducted a pharmacokinetic study for EDR and EDR COAM in fasted and fed conditions to check effect of food on its oral absorption. The LC-MS/MS-based method was developed and validated to determine the amount of EDR in plasma.

RESULTS

The results suggested that EDR COAM did not show a significant difference in Cmax (P=0.3544) and AUC (P=0.1696) of fasted and fed states. On the other hand, plain EDR showed 2-fold and 3-fold reduced Cmax (P<0.0001) and AUC (P=0.0094) in the fed condition, respectively. The Cmax and AUC of EDR COAM were improved in fasted (AUC: 2.56-fold) and fed states (AUC: 5.74-fold) than plain EDR, suggesting better oral absorption of COAM than crystalline EDR without having the effect of food.

CONCLUSIONS

The unique structural attributes of NaTC had the potential to inhibit the recrystallization of EDR in GIT, while concurrently reducing the impact of food on the oral absorption of EDR.

Nrf2 Signaling Pathway: a Potential Therapeutic Target in Combating Oxidative Stress and Neurotoxicity in Chemotherapy-Induced Cognitive Impairment

Chemotherapy-induced cognitive impairment (CICI) is one of the major adverse effects of antineoplastic drugs, which decrease the quality of life in cancer survivors. Extensive experimental and clinical research suggests that chemotherapeutic drugs generate an enormous amount of reactive oxygen species (ROS), contributing to oxidative stress, neuroinflammation, blood-brain barrier (BBB) disruption, and neuronal death, eventually leading to CICI. Despite the progress in exploring different pathological mechanisms of CICI, effective treatment to prevent CICI progression has not been developed yet. Nrf2 is the principal transcription factor that regulates cellular redox balance and inflammation-related gene expression. Emerging evidence suggests that upregulation of Nrf2 and its target genes could suppress oxidative stress, and neuroinflammation, restore BBB integrity, and increase neurogenesis. This review discusses the role of Nrf2 in CICI, how it responds to oxidative stress, inflammation, neurotoxicity, and potential Nrf2 activators that could be used to enhance Nrf2 activation in CICI.

Neuroprotective Effects of Probucol against Rotenone-Induced Toxicity via Suppression of Reactive Oxygen Species Production in SH-SY5Y Cells

Probucol is a hyperlipidemic drug with antioxidant properties. It has been reported to prevent mitochondrial dysfunction, reduce oxidative stress, and suppress neurotoxicity in neurodegenerative disease models, including Parkinson's disease models. However, the molecular mechanisms underlying the neuroprotective effects of probucol have been not examined yet. Thus, in this study, we investigated whether probucol can alleviate the effects of a mitochondrial complex I inhibitor, rotenone, on a human neuroblastoma cell line (SH-SY5Y). We evaluated the cell viability and cytotoxicity and apoptosis rates of SH-SY5Y cells treated with rotenone and probucol or edaravone, a known free-radical scavenger. Subsequently, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) levels in the cells were evaluated to determine the effects of probucol on mitochondrial function. We found that rotenone caused cytotoxicity, cell apoptosis, and mitochondrial dysfunction, enhanced ROS generation, and impaired MMP. However, probucol could inhibit this rotenone-induced decrease in cell viability, MMP loss, intracellular ROS generation, and apoptosis. These results suggest that probucol exerts neuroprotective effects via MMP stabilization and the inhibition of ROS generation. Additionally, this effect of probucol was equal to or greater than and more persistent than that of edaravone. Thus, we believe probucol may be a promising drug for the treatment of neurodegenerative diseases, such as Parkinson's and Alzheimer's diseases.

Sericin alleviates motor dysfunction by modulating inflammation and TrkB/BDNF signaling pathway in the rotenone-induced Parkinson's disease model

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the degeneration of nigrostriatal dopaminergic neurons and movement impairment. Based on theories, neuroinflammatory processes may be vital in the etiology of PD and other neurodegenerative diseases. Reports show that rotenone has neurotoxic, inflammatory, and motor impairment effects in PD. Sericin is a natural polymer with effective properties, such as neuroprotective and anti-inflammatory. Therefore, this study aimed to examine the effects of sericin administration on motor dysfunction by modulating inflammation and tyrosine kinase B/brain-derived neurotrophic factor (TrkB/BDNF) pathway in the rotenone-induced PD model.

METHODS

Wistar male rats (3-months-old) were treated with rotenone (2 mg/kg every 48 h for 30 days) to induce a rotenone-induced PD model. Also, sericin was administered orally at dose of 200 mg/kg every 48 h for 30 days. Rotarod and bar tests were performed for motor dysfunction. The protein levels of BDNF, c-fos, TrkB, tumor necrosis factor- α (TNF-α), interleukin-6 (IL-6) and catalase activity were evaluated in the striatum area.

RESULTS

Results showed that sericin increased latent time in the rotarod test and decreased the time staying on the pole in the bar test compared to the PD group (P < 0.001 for both tests). Moreover, sericin treatments decreased TNF-α (P < 0.001) and IL-6 (P < 0.001) concentration levels and enhanced the levels of BDNF (P < 0.001), c-fos (P < 0.001), TrkB (P < 0.001) proteins and catalase activity (P < 0.05) in the striatum area compared to the PD group.

CONCLUSION

These results support a protective benefit of sericin therapy in a rotenone-induced PD paradigm by reducing motor impairment, inflammatory response, and disruption of the TrkB/BDNF signaling pathway.

Effects of the Edaravone, a Drug Approved for the Treatment of Amyotrophic Lateral Sclerosis, on Mitochondrial Function and Neuroprotection

Edaravone, the first known free radical scavenger, has demonstrated cellular protective properties in animals and humans. Owing to its antioxidant activity, edaravone modulates oxidative damage in various diseases, especially neurodegenerative diseases. In 2015, edaravone was approved in Japan to treat amyotrophic lateral sclerosis. The distinguishing pathogenic features of neurodegenerative diseases include high reactive oxygen species levels and mitochondrial dysfunction. However, the correlation between mitochondria and edaravone has not been elucidated. This review highlights recent studies on novel therapeutic perspectives of edaravone in terms of its effect on oxidative stress and mitochondrial function.

The potential neuroprotective effect of diosmin in rotenone-induced model of Parkinson's disease in rats

Most treatments for Parkinson's disease (PD) focus on improving the symptoms and the dopaminergic effects; nevertheless, they cannot delay the disease progression. Diosmin (DM), a naturally occurring flavone that is obtained from citrus fruits, has demonstrated anti-apoptotic, anti-inflammatory and antioxidative properties in many diseases. This study aimed to assess the neuroprotective effects of diosmin in rotenone-induced rat model of PD and investigate its potential underlying mechanisms. A preliminary dose-response study was conducted where rats were treated with DM (50,100 and 200 mg/kg, p.o.) concomitantly with rotenone (2 mg/kg, s.c.) for 4 weeks. Catalepsy, motor impairment, spontaneous locomotion, body weight, histological examination and tyrosine hydroxylase (TH) immunoreactivity were evaluated in both the midbrains and striata of rats. Treatment with DM (200 mg/kg) showed the most promising outcome therefore, it was selected for further evaluation of α-synuclein, Bax, Bcl2, nuclear factor kappa B (NF-кB), nuclear factor erythroid 2- related factor 2 (Nrf2), and heme oxygenase-1 (HO-1), in addition to biochemical analysis of tumor necrosis factor-α (TNF-α). Results showed that DM (200 mg/kg, p.o.) prevented rotenone-induced motor impairment, weight reduction and histological damage. Furthermore, it significantly inhibited rotenone-induced decrease in TH expression. These results were correlated with reduction in α-synuclein immunoreactivity, together with improvement of Bax/Bcl2 ratio compared to rotenone group. DM also attenuated rotenone-induced increase in NF-кB expression as well as TNF- α levels. Moreover, DM inhibited rotenone-induced upregulation of Nrf2/HO-1 pathway. Thus, the current study suggests that DM might be a promising candidate for managing the neuropathological course of PD.

The association of Edaravone with shunt surgery improves behavioral performance, reduces astrocyte reaction and apoptosis, and promotes neuroprotection in young hydrocephalic rats

The neuroprotective effect of Edaravone in young hydrocephalic rats associated with a CSF derivation system was evaluated. The drug has already been shown to be beneficial in experimental hydrocephalus, but the combination of this drug with shunt surgery has not yet been investigated. Fifty-seven-day-old Wistar rats submitted to hydrocephalus by injection of kaolin in the cisterna magna were used and divided into five groups: control (n = 10), hydrocephalic (n = 10), hydrocephalic treated with Edaravone (20 mg/kg/day) (n = 10), hydrocephalic treated with shunt (n = 10) and hydrocephalic treated with shunt and Edaravone (n = 10). Administration of the Edaravone was started 24 h after hydrocephalus induction (P1) and continued until the experimental endpoint (P21). The CSF shunt surgery was performed seven days after hydrocephalus induction (P7). Open-field tests, histological evaluation by hematoxylin and eosin, immunohistochemistry by Caspase-3 and GFAP, and ELISA biochemistry by GFAP were performed. Edaravone reduced reactive astrogliosis in the corpus callosum and germinal matrix (p < 0.05). When used alone or associated with CSF shunt surgery, the drug decreased the cell death process (p < 0.0001) and improved the morphological aspect of the astroglia (p < 0.05). The results showed that Edaravone associated with CSF bypass surgery promotes neuroprotection in young hydrocephalic rats by reducing reactive astrogliosis and decreasing cell death.

Drug Repurposing: Promises of Edaravone Target Drug in Traumatic Brain Injury

Edaravone is a potent free-radical scavenger that has been in the market for more than 30 years. It was originally developed in Japan to treat strokes and has been used there since 2001. Aside from its anti-oxidative effects, edaravone demonstrated beneficial effects on proinflammatory responses, nitric oxide production, and apoptotic cell death. Interestingly, edaravone has shown neuroprotective effects in several animal models of diseases other than stroke. In particular, edaravone administration was found to be effective in halting amyotrophic lateral sclerosis (ALS) progression during the early stages. Accordingly, after its success in Phase III clinical studies, edaravone has been approved by the FDA as a treatment for ALS patients. Considering its promises in neurological disorders and its safety in patients, edaravone is a drug of interest that can be repurposed for traumatic brain injury (TBI) treatment. Drug repurposing is a novel approach in drug development that identifies drugs for purposes other than their original indication. This review presents the biochemical properties of edaravone along with its effects on several neurological disorders in the hope that it can be adopted for treating TBI patients.

Microemulsion-based gel for the transdermal delivery of rasagiline mesylate: In vitro and in vivo assessment for Parkinson's therapy

Rasagiline mesylate (RSM) is a selective and irreversible monoamine oxidase B inhibitor used for the treatment of Parkinson's disease (PD). However, its unfavorable biopharmaceutical properties, such as extensive degradation in the gastrointestinal tract and first-pass metabolism are responsible for its low oral bioavailability and suboptimal therapeutic efficacy. Here, we report the feasibility of delivering RSM via the transdermal route using RSM containing microemulsion-based gel (RSM-MEG) to achieve effective management of PD. Our in vitro skin permeation studies of RSM-MEG showed significantly higher (at least ~1.5-fold) permeation across rat skin compared to the conventional RSM hydrogel. Our skin irritation studies in rabbits showed that RSM-MEG is safe for transdermal application. Finally, using the rat model of rotenone-induced Parkinsonism, we demonstrated that the topical application of RSM-MEG was equally effective in reversing PD symptoms when compared to oral RSM therapy. Thus, our study confirmed the feasibility and potential of transdermal delivery of RSM via simple topical application of RSM-MEG, and this approach could be an alternative therapeutic intervention for the treatment of Parkinson's disease.

Can Cranberry Juice Protect against Rotenone-Induced Toxicity in Rats?

The high polyphenols content of cranberry accounts for its strong antioxidant activity underlying the beneficial health effects of this fruit. Rotenone (ROT) is a specific inhibitor of mitochondrial complex I in the brain which leads to the generation of oxidative stress. To date, there are few data indicating that toxicity of ROT is not limited to the brain but can also affect other tissues. We aimed to examine whether ROT-induced oxidative stress could be counteracted by cranberry juice not only in the brain but also in the liver and kidney. Wistar rats were given the combined treatment with ROT and cranberry juice (CJ) for 35 days. Parameters of antioxidant status were determined in the organs. ROT enhanced lipid peroxidation solely in the brain. The increase in the DNA damage was noticed in all organs examined and in leukocytes. The beneficial effect of CJ on these parameters appeared only in the brain. Additionally, CJ decreased the activity of serum hepatic enzymes. The effect of CJ on antioxidant enzymes was not consistent, however, in some organs, CJ reversed changes evoked by ROT. Summing up, ROT can cause oxidative damage not only in the brain but also in other organs. CJ demonstrated a protective effect against ROT-induced toxicity.

Role of Edaravone as a Treatment Option for Patients with Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease, is a progressive and fatal neurodegenerative disease that leads to a loss of muscle control due to nerve cells being affected in the brain and spinal cord. Some of the common clinical presentations of ALS include weakness of muscles, changes in behavior, dysfunction in speech, and cognitive difficulties. The cause of ALS is uncertain, but through several studies, it is known that mutations in SOD1 or C9orf72 genes could play a role as a factor of ALS. In addition, studies indicate that an excessive amount of free radicals, the reactive oxygen species (ROS), leads to neuronal damage by the peroxidation of unsaturated fatty acids in the neuronal cells. Edaravone, the newly approved antioxidant drug for ALS, halts the progression of ALS in the early stages through its cytoprotective effect and protects the nerves by reducing ROS. In this review, different aspects of ALS will be discussed, including its pathology, genetic aspect, and diagnosis. This review also focuses on edaravone as a treatment option for ALS, its mechanism of action, and its pharmacological properties. Clinical trials and adverse effects of edaravone and care for ALS patient are also discussed.

Isolongifolene mitigates rotenone-induced dopamine depletion and motor deficits through anti-oxidative and anti-apoptotic effects in a rat model of Parkinson's disease

Isolongifolene (ILF), a novel tricyclic sesquiterpene compound isolated from the Indian herb Murraya koenigii (M. koenigii), has been previously demonstrated to have a neuroprotective effect against rotenone-induced oxidative stress, mitochondrial dysfunction, and apoptosis in in vitro model. However, these neuroprotective and anti-apoptotic effects of ILF are not well understood and must be further investigated to elucidate the underlying molecular mechanism of ILF in animal experiments. The objective of this study was to evaluate the neuroprotective effect of ILF on motor impediments, neurochemical variables, anti-oxidative indices, and apoptotic protein expression in a rotenone-induced rat model of Parkinson's disease (PD). PD was induced in male albino Wistar rats via injection of 2.5 mg/kg rotenone for 4 weeks. Rotenone produces PD-like effects by promoting mitochondrial complex I inhibition and microglial activation properties. The protective effect of three different doses of ILF 5, 10 and 20 mg/kg were evaluated for spontaneous locomotion, rotarod performance, and striatal dopamine (DA) content. The results showed that ILF dose-dependently ameliorated the rotenone-induced striatal DA loss and motor impairment from 10 mg/kg. Therefore, we selected 10 mg/kg as the ILF dose for further investigation. Chronic administration of rotenone caused PD-related pathological processes like oxidative stress, and produced a significant decrease in tyrosine hydroxylase (TH), DA transporter (DAT), Vesicular monoamine transporter 2 (VMAT2), and a significant upregulated in α-synuclein and apoptotic protein expression of Bax, Cyt-C and caspases -3, -8 and -9 as well as by decreasing Bcl2 expression. Treatment with ILF 10 mg/kg mitigated oxidative stress in rotenone-treated rats. Furthermore, ILF dramatically alleviated rotenone-induced toxicity and cell death by increasing TH, DAT and VMAT2 expression and reducing the upregulation of α-synuclein, Bax, Cyt-C, caspases -3, -8 and -9. Together, our results confirm that ILF's protective effect against rotenone-induced PD is mediated through anti-oxidant and anti-apoptotic properties. However, further in-depth investigations on ILF's anti-inflammatory and mitochondrial protective abilities are needed to establish ILF as a potential drug candidate for the treatment of Parkinson's disease.

Protective effect of edaravone against radiation-induced ovarian injury: a histopathological and immunohistochemical evaluation in an experimental rat model

PURPOSE

We aimed to evaluate the protective effect of edaravone on radiation-induced ovarian damage in an experimental rat model.

METHODS

Thirty-two Wistar albino female rats were randomly divided into four groups. Group 1: control, no treatment, and radiation was applied throughout the study; Group 2: sham, only radiation was applied; Group 3: 45 mg/kg edaravone and radiation were applied; Group 4: 450 mg/kg edaravone and radiation were applied. Edaravone was administered intraperitoneally 30 min before radiotherapy (5 Gy). Two days after radiation exposure, the rats were sacrificed and the ovaries were removed. Histologic changes under light microscopy and immunoreactivity for anti-caspase-3 were noted and compared between the four groups.

RESULTS

There was a statistically significant difference in follicle counts, vascular congestion, edema, cytoplasmic vacuolization, hemorrhage, and interstitial cell degeneration between the groups. Radiation causes deterioration in most histopathological parameters. Administration of edaravone at different doses seems to reverse these alterations and alleviate the injury. Antioxidant defense mechanisms appear to be enhanced by edaravone as shown by histopathologically and decreased apoptosis by reducing the expression of anti-caspase-3 activity as demonstrated immunohistochemically.

CONCLUSION

This is the first study evaluating the protective effects of edaravone on radiation-induced ovarian damage. Edaravone decreased the follicular apoptosis and attenuates the radiation-induced ovarian damage in rats.

Evaluation of the Anti-apoptotic and Anti-cytotoxic Effect of Epicatechin Gallate and Edaravone on SH-SY5Y Neuroblastoma Cells

Introduction:

Parkinson disease (PD) is the second most common neurodegenerative disease affecting older individuals with signs of motor disability and cognitive impairment. Epicatechin (EC) and edaravone have neuroprotective effects most probably due to their antioxidant activity; however, a limited number of studies have considered their role in PD. This research aimed at investigating the neuroprotective effect of EC and edaravone in a neurotoxin-induced model of PD.

Methods:

An in vitro model of PD was made by subjecting SH-SY5Y neuroblastoma cells to neurotoxin: 6-hydroxydopamine (6-OHDA) 100 μM/well. The cytoprotective effect of EC and edaravone in five concentrations on cell viability was tested using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. The apoptotic assay was done by annexin V and propidium iodide method using flow cytometry.

Results:

According to the MTT assay analysis, EC and edaravone had protective effects against 6-OH DA-induced cytotoxicity in SH-SY5Y neuroblastoma cells that were much more significant for edaravone and also a relative synergistic effect between EC and edaravone was observed. The apoptotic analysis showed that edaravone alone could decrease early and late apoptosis, whereas EC diminished early apoptosis, but enhanced late apoptosis and necrosis. Besides, co-treatment of edaravone and EC had a synergistic effect on decreasing apoptosis and increasing cell viability.

Conclusion:

The protective effect of edaravone on apoptosis and cytotoxicity was demonstrated clearly and EC had a synergistic effect with edaravone.

The Cataleptic, Asymmetric, Analgesic, and Brain Biochemical Effects of Parkinson's Disease Can Be Affected by Toxoplasma gondii Infection

Purpose

Parkinson's disease (PD) is a neurodegenerative disorder with progressive motor defects. Therefore, the aim of the present investigation was to examine whether catalepsy, asymmetry, and nociceptive behaviors; the Nissl-body and neuron distribution; brain-derived neurotrophic factor (BDNF); malondialdehyde (MDA); total antioxidant capacity (TAC) levels; and the percentage of dopamine depletion of striatal neurons in the rat model of Parkinson's disease (PD) can be affected by Toxoplasma gondii (TG) infection.

Methods

Fifty rats were divided into five groups: control (intact rats), sham (rats which received an intrastriatal injection of artificial cerebrospinal fluid (ACSF)), PD control (induction of PD without TG infection), TG control (rats infected by TG without PD induction), and PD infected (third week after PD induction, infection by TG was done). PD was induced by the unilateral intrastriatal microinjection of 6-hydroxydopamine (6-OHDA) and ELISA quantified dopamine, BDNF, MDA, and TAC in the striatum tissue. Cataleptic, asymmetrical, nociceptive, and histological alterations were determined by bar test, elevated body swing test, formalin test, and Nissl-body and neuron counting in the striatal neurons.

Results

The results demonstrated that PD could significantly increase the number of biased swings, descent latency time, and nociceptive behavior and decrease the distribution of Nissl-stained neurons compared to the control and sham groups. TG infection significantly improved biased swing, descent latency time, nociceptive behavior, and the Nissl-body distribution in striatal neurons in comparison to the PD control group. The striatal level of BDNF in the PD-infected and TG control groups significantly increased relative to the PD control group. The striatal MDA was significantly higher in the PD control than other groups, while striatal TAC was significantly lower in the PD control than other groups.

Conclusions

The current study indicates that TG infection could improve the cataleptic, asymmetric, nociceptive and behaviors; the level of striatal dopamine release; BDNF levels; TAC; and MDA in PD rats.

3-Nitrotyrosine: a versatile oxidative stress biomarker for major neurodegenerative diseases

Reactive oxygen species are generated as a by-product of routine biochemical reactions. However, dysfunction of the antioxidant system or mutations in gene function may result in the elevated production of the pro-oxidant species. Modified endogenous molecules due to chemical interactions with increased levels of reactive oxygen and nitrogen species in the cellular microenvironment can be termed as biomarkers of oxidative stress. 3-Nitrotyrosine is one such promising biomarker of oxidative stress formed due to nitration of protein-bound and free tyrosine residues by reactive peroxynitrite molecules. Nitration of proteins at the subcellular level results in conformational alterations that damage the cytoskeleton and result in neurodegeneration. In this review, we summarized the role of oxidative/nitrosative processes as a contributing factor for progressive neurodegeneration in Alzheimer's disease, Parkinson's disease, Huntington's disease, Lou Gehrig's disease and Prion disease. The selective tyrosine protein nitration of the major marker proteins in related pathologies has been discussed. The alteration in 3-Nitrotyrosine profile occurs well before any symptoms appear and can be considered as a potential target for early diagnosis of neurodegenerative diseases. Furthermore, the reduction in 3-Nitrotyrosine levels in response to treatment with neuroprotective has been highlighted which is indicative of the importance of this particular marker in oxidative stress-related brain and central nervous system pathologies.

miR-185 and SEPT5 Genes May Contribute to Parkinson's Disease Pathophysiology

There are still unknown mechanisms involved in the development of Parkinson's disease (PD), which elucidating them can assist in developing efficient therapies. Recently, studies showed that genes located on the human chromosomal location 22q11.2 might be involved in the development of PD. Therefore, the present study was designed to evaluate the role of two genes located on the chromosomal location (miR-185 and SEPT5), which were the most probable candidates based on our bibliography. In vivo and in vitro models of PD were developed using male Wistar rats and SHSY-5Y cell line, respectively. The expression levels of miR-185, SEPT5, LRRK2, and PARK2 genes were measured at a mRNA level in dopaminergic areas of rats' brains and SHSY-5Y cells using the SYBR Green Real-Time PCR Method. Additionally, the effect of inhibition on the genes or their products on cell viability and gene expression pattern in SHSY-5Y cells was investigated. The level of miR-185 gene expression was significantly decreased in the substantia nigra (SN) and striatum (ST) of the rotenone-treated group (control group) compared to the healthy normal group (P < 0.05). In addition, there was a significant difference in the expression of SEPT5 gene (P < 0.05) in the substantia nigra between two studied groups. The results of an in vitro study showed no significant change in the expression of the genes; however, the inhibition on miR-185 gene expression led to the increase in LRRK2 gene expression in SHSY-5Y cells. The inhibition on LRRK2 protein also decreased the cellular toxicity effect of rotenone on SHSY-5Y cells. The results suggested the protective role of miR-185 gene in preventing the development of PD.

Edaravone-caffeine combination for the effective management of rotenone induced Parkinson's disease in rats: An evidence based affirmative from a comparative analysis of behavior and biomarker expression

Restoration of cellular microenvironment is important in the treatment of neurodegenerative diseases for optimal functioning and survival of neurons. Oxidative stress has been proposed as one of the major pathogenic drivers in Parkinson's disease. Parkinson's model was developed by chronic administration of a pesticide rotenone that inhibits mitochondrial complex I resulting in generation of reactive oxygen species. In this study, our aim was to evaluate neuroprotective effect rendered by edaravone, a potent free radical scavenger in combination with caffeine, an effective inhibitor of adenosine A2A receptor as well as a proven antioxidant. Here we demonstrate that a three-week treatment with edaravone-caffeine combination was able to significantly diminish rotenone induced oxidative damage at the cellular level as well as muscle weakness and cognitive impairment generally associated with Parkinson's disease. This effect is attributable to edaravone's capability of scavenging the perxoynitrite free radical. Herein, we have assessed the levels of protein nitroxidation marker 3-nitrotyrosine in the striatum and lipid peroxidation marker malondialdehyde in striatum, cerebrospinal fluid, plasma and urine of rats. On the 21^st day, statistical difference was observed in the striatal biomarker levels (p = 0.001) between the controls, treated and untreated groups. We discovered that when edaravone was co-administered with caffeine, the effect was more significant compared to the group solely treated with edaravone demonstrating a synergistic effect. Simultaneous therapeutic intervention with drug combination showed a pronounced decrease in oxidative damage markers as well as better muscle strength and cognition compared to the untreated groups.

Multiple pathways for natural product treatment of Parkinson's disease: A mini review

BACKGROUND

It is established that natural medicines for Parkinson's disease (PD) provide an antioxidant activity in preventing dopaminergic neurons from degeneration. However, the underlying and related molecular details remain poorly understood.

METHODS AND AIM

We review published in vitro and rodent studies of natural products in PD models with the aim to identify common molecular pathways contributing to the treatment efficacy. Commonly regulated genes were identified through the systemic literature search and further analyzed from a network perspective.

FINDINGS

Approximately thirty different types of natural products have been investigated for their ability to regulate protein density and gene activity in various experimental systems. Most were found to attenuate neurotoxin-induced regulations. Three common PD pathways are involved. The most studied pathway was neuronal development/anti-apoptosis consisting of Bax/Bcl-2, caspases 3/9, and MAPK signaling. Another well studied was anti-inflammation comprising iNOS, nNOS, Nrf2/ARE, cytokines, TNFα, COX2 and MAPK signaling. The third pathway referred to dopamine transmission modulation with upregulated VMAT2, DAT, NURR1 and GDNF levels. To date, HIPK2, a conserved serine/threonine kinase and transcriptional target of Nrf2 in an anti-apoptosis signaling pathway, is the first protein identified as the direct binding target of a natural product (ZMHC).

IMPLICATIONS

Natural products may utilize multiple and intercellular pathways at various steps to prevent DA neurons from degeneration. Molecular delineation of the mechanisms of actions is revealing new, perhaps combinational therapeutic approaches to stop the progression of DA degeneration.

Edaravone inhibits the conformational transition of amyloid-β42: insights from molecular dynamics simulations

Previous work has shown that edaravone inhibits fibrillogenesis of amyloid-β protein (Aβ). However, the detailed mechanism by which edaravone inhibits the conformational transition of the Aβ42 monomer is not known at the molecular level. Here, explicit-solvent molecular dynamics (MD) simulations were coupled with molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) method to address the issue. MD simulations confirmed that edaravone inhibits the conformational transition of the Aβ42 monomer in a dose-dependent manner. It was found that the direct interactions between edaravone and Aβ42 are responsible for its inhibiting effects. The analysis of binding free energy using the MM-PBSA method demonstrated that the nonpolar interactions provide favourable contributions (about -71.7 kcal/mol). Conversely, the polar interactions are unfavourable for the binding process. A total of 14 residues were identified as greatly contributing to the binding free energy between edaravone and the Aβ42 monomer. In addition, the intra-peptide hydrophobic interactions were weakened and the salt bridge D23-K28 was interrupted by edaravone. Therefore, the conformational transition was inhibited. Our studies provide molecular-level insights into how edaravone molecules inhibit the conformational transition of the Aβ42 monomer, which may be useful for designing amyloid inhibitors.Communicated by Ramaswamy H. Sarma.

Edaravone reduces Aβ-induced oxidative damage in SH-SY5Y cells by activating the Nrf2/ARE signaling pathway

AIMS

Edaravone potentially alleviates cognitive deficits in a mouse model of Alzheimer's disease (AD). However, the mechanism of edaravone in suppressing AD progression remains unclear. We aim to investigate the mechanism of edaravone in suppressing oxidative stress-mediated AD progression in vitro.

MAIN METHODS

Human neuroblastoma SH-SY5Y cells were pretreated with different concentrations of edaravone prior to the induction by Aβ_25-35. Cell viability, apoptosis, reactive oxygen species, and expression of antioxidative response elements (ARE) including Nrf2, SOD, and HO-1 were assessed.

KEY FINDINGS

The results showed that apoptosis and reactive oxygen species levels significantly increased in Aβ_25-35-treated cells, whereas the mRNA and protein levels of Nrf2, SOD and HO-1 decreased. The opposite changes were observed in cells that were pre-treated with edaravone, particularly at a concentration of 40 μM. Aβ_25-35-treatment suppressed Nrf2 expression and nuclear translocation were rescued by Edaravone. Genetic inhibition of Nrf2 greatly decreased the protective effect of edaravone against cell apoptosis and cytotoxicity induced by Aβ_25-35, accompanied by decreases in SOD and HO-1 expression.

SIGNIFICANCE

Activation of the Nrf2/ARE signaling pathway may underlie the protective effects of edaravone against the oxidative damage associated with Alzheimer's disease.

Neuroprotective role of chrysin in attenuating loss of dopaminergic neurons and improving motor, learning and memory functions in rats

OBJECTIVE

Selective degeneration of dopaminergic neurons is the pathological hallmark of Parkinson disease (PD). Enhanced oxidative stress, lipid peroxidation and susceptibility of dopaminergic neurons to apoptotic cellular death are the leading pathogenetic mechanisms. Chrysin is an active flavonoid. Its neuroprotective effects have been reported. This study examined the neuroprotective effects of chrysin in ameliorating the dopaminergic neuronal degeneration and motor behavioral changes in rotenone model of PD.

METHODS

Thirty Sprague-Dawley rats were assigned into three groups: Control, rotenone-treated, and rotenone+chrysin treated groups. Rotenone was given at a dose of 3 mg/kg daily intraperitoneally, and chrysin was given at a dose of 50 mg/kg daily intraperitoneally for 4 weeks. Using five neurobehavioral assessment tests, evaluation was done weekly to record the motor behavioral changes. After 4 weeks, animals were sacrificed, brains were removed, and section from striatum and substantia nigra were stained using hematoxylin and eosin and cresyl violet stains. Immunohistochemical sections were also prepared using anti-tyrosine hydroxylase (TH) antibody.

RESULTS

Rotenone-induced Parkinson like changes were evident from deteriorating motor behavior. These animals showed extensive loss of dopaminergic neurons, decreased immunoreactivity against anti-TH antibodies and number of TH positive dopaminergic neurons in the nigrostriatal region. Chrysin treated animals showed a significant reduction in motor behavioral changes, degeneration and loss of nigrostriatal dopaminergic neurons and increased immunoreactivity to anti-TH antibody.

CONCLUSION

This study concludes that chrysin confers neuroprotection in rat model of PD. It attenuates the degeneration of the nigrostriatal dopaminergic neurons and motor behavioral abnormalities.

Streptozotocin inhibits synaptic transmission and edaravone attenuates streptozotocin-induced electrophysiological changes in CA1 pyramidal neurons of rat hippocampal slices

The purpose of this study was to investigate the acute and chronic effects of streptozotocin (STZ) upon synaptic transmission and the effects of edaravone (EDA, a free radical scavenger) on STZ-induced electrophysiological changes in CA1 pyramidal neurons of rat hippocampal slices. To accomplish this goal, spontaneous excitatory postsynaptic current (sEPSC), miniature excitatory postsynaptic current (mEPSC), spontaneous inhibitory postsynaptic current (sIPSC) and miniature inhibitory postsynaptic current (mIPSC) were recorded within hippocampal slices using whole-cell patch clamp techniques. The results showed that the amplitudes and frequencies of sEPSC, mEPSC, sIPSC and mIPSC were inhibited by 1000μM STZ, while treatment of EDA (1000μM) attenuated these STZ-induced changes. The degree of these neurotoxic effects of STZ and effects of EDA increased as a function of drug duration as assessed at 2, 4 or 8h of exposure. Taken together, our results demonstrate that STZ induces neurotoxicity within these hippocampal slices through its capacity to alter synaptic transmission and these STZ-induced alterations in electrophysiological responses are attenuated by EDA.

Tetramethylpyrazine Ameliorates Rotenone-Induced Parkinson's Disease in Rats: Involvement of Its Anti-Inflammatory and Anti-Apoptotic Actions

Parkinson's disease (PD) is a slowly progressive neurodegenerative movement disorder. Apoptosis, neuroinflammation, and oxidative stress are the current hypothesized mechanisms for PD pathogenesis. Tetramethylpyrazine (TMP), the major bioactive component of Ligusticum wallichii Franchat (ChuanXiong), Family Apiaceae, reportedly has anti-apoptotic, anti-inflammatory and antioxidant effects. This study investigated the role of 'TMP' in preventing rotenone-induced neurobiological and behavioral sequelae. A preliminary dose-response study was conducted where rats received TMP (10, 20, and 40 mg/kg, i.p.) concomitantly with rotenone (2 mg/kg, s.c.) for 4 weeks. Catalepsy, locomotor activity, striatal dopamine content, and tyrosine hydroxylase "TH" and α-synuclein immunoreactivity were evaluated. The selected TMP dose (20 mg/kg) was used for western blot analysis of Bax, Bcl2, and DJ-1, immunohistochemical detection of nuclear factor kappa B (NF-кB), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), and glial fibrillary acidic protein (GFAP) expression, in addition to biochemical analysis of caspase-3 activity, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) levels. Results showed that TMP (20 mg/kg) significantly improved midbrain and striatal TH expression and striatal dopamine content as well as the motor deficits, compared to rotenone-treated group. These results were correlated with reduction in caspase-3 activity and α-synuclein expression, along with improvement of midbrain and striatal Bax/Bcl2 ratio compared to rotenone-treated group. TMP also attenuated rotenone-induced upregulation of Nrf2/HO-1 pathway. Furthermore, TMP downregulated rotenone-induced neuroinflammation markers: NF-кB, iNOS, COX2, and GFAP expression in both the midbrain and striatum. Taken together, the current study suggests that TMP is entitled to, at least partially, preventing PD neurobiological and behavioral deficits by virtue of its anti-apoptotic, anti-inflammatory, and antioxidant actions.

Edaravone alleviates cisplatin-induced neurobehavioral deficits via modulation of oxidative stress and inflammatory mediators in the rat hippocampus

Cisplatin is a chemotherapeutic agent used in the treatment of malignant tumors. A major clinical limitation of cisplatin is its potential toxic effects, including neurotoxicity. Edaravone, a potent free radical scavenger, has been reported to have the neuroprotective effect against neurological deficits. The aim of the present study was to determine the neuroprotective effect of edaravone against cisplatin-induced behavioral and biochemical anomalies in male Wistar rats. Our results showed that cisplatin (5mg/kg/week, i.p.) administration for seven weeks caused marked cognitive deficits and motor incoordination in rats. This was accompanied by oxido-nitrosative stress, neuroinflammation, NF-κB activation and down-regulation of Nrf2/HO-1 gene expression level in the hippocampus. Edaravone (10mg/kg/week, i.p.) treatment for seven weeks inhibited the aforementioned neurobehavioral and neurochemical deficits. Furthermore, edaravone was found to up-regulate the gene expression level of Nrf2/HO-1 and prevented the cisplatin-induced NF-κB activation. These findings demonstrated that oxido-nitrosative stress and inflammatory signaling mediators play a key role in the development of cisplatin-induced neurobehavioral deficits which were prevented by edaravone treatment.

hVMAT2: A Target of Individualized Medication for Parkinson's Disease

Vesicular monoamine transporter 2 (VMAT2) is responsible for sequestering cytosolically toxic dopamine into intracellular secretory vesicles. Animal genetic studies have suggested that reduced VMAT2 activity contributes to the genetic etiology of Parkinson's disease (PD), but this role has not been established in humans. Based on human genetic association and meta-analysis, we first confirm the human VMAT2 (hVMAT2 or SLC18A2) promoter as a risk factor for PD in both family and unrelated US white people: marker rs363324 at -11.5 kb in the hVMAT2 promoter is reproducibly associated with PD in a cohort of nuclear families (p = 0.04506 in early-onset PD) and 3 unrelated US white people (meta-analysis p = 0.01879). In SH-SY5Y cells, low activity-associated hVMAT2 promoter confers high methylpiperidinopyrazole iodide cytotoxicity, which is likely attributed to functional polymorphisms bound by nuclear proteins. Interestingly, treatments with the dopamine neuron-protecting agent puerarin upregulates the promoter activity in a haplotype- and cell line-dependent manner. These pharmacogenetic findings suggest that hVMAT2 could be a risk factor and imply it as a target of genetic medications for PD.

Ameliorative Effect of Quercetin on Neurochemical and Behavioral Deficits in Rotenone Rat Model of Parkinson's Disease: Modulating Autophagy (Quercetin on Experimental Parkinson's Disease)

Autophagy is necessary for neuronal homeostasis and its dysfunction has been implicated in Parkinson's disease (PD) as it can exacerbate endoplasmic reticulum (ER) stress and ER stress-induced apoptosis. Quercetin is a flavonoid known for its neuroprotective and antioxidant effects. The present study investigated the protective, autophagy-modulating effects of quercetin in the rotenone rat model of PD. Rotenone was intraperitoneally injected at dose of 2 ml/kg/day for 4 weeks. Simultaneous intraperitoneal injection of quercetin was given at a dose of 50 mg/kg/day also for 4 weeks. Neurobehavioral changes were studied. Oxidative/antioxidant status, C/EBP homologous protein (CHOP), Beclin-1, and dopamine levels were assessed. DNA fragmentation and histopathological changes were evaluated. This research work revealed that quercetin significantly attenuated rotenone-induced behavioral impairment, augmented autophagy, ameliorated ER stress- induced apoptosis with attenuated oxidative stress. From the current study, quercetin can act as an autophagy enhancer in PD rat model and modulates the microenvironment that leads to neuronal death.

Edaravone offers neuroprotection for acute diabetic stroke patients

INTRODUCTION

Edaravone, a novel free-radical scavenger, has been shown to alleviate cerebral ischemic injury and protect against vascular endothelial dysfunction. However, the effects of edaravone in acute diabetic stroke patients remain undetermined.

METHODS

A randomized, double-blind, placebo-controlled study was performed to prospectively evaluate the effects of edaravone on acute diabetic stroke patients admitted to our hospital within 24 h of stroke onset. The edaravone group received edaravone (30 mg twice per day) diluted with 100 ml of saline combined with antiplatelet drug aspirin and atorvastatin for 14 days. The non-edaravone group was treated only with 100 ml of saline twice per day combined with aspirin and atorvastatin. Upon admission, and on days 7, 14 post-stroke onset, neurological deficits and activities of daily living were assessed using the National Institutes of Health Stroke Scale (NIHSS) and the Barthel Index (BI), respectively. The occurrence of hemorrhage transformation, pulmonary infection, progressive stroke and epilepsy was also evaluated on day 14 post-treatment.

RESULTS

A total of 65 consecutive acute diabetic stroke patients were enrolled, of whom 35 were allocated to the edaravone group and 30 to the non-edaravone group. There was no significant group difference in baseline clinical characteristics, but mean NIHSS scores were lower (60 %), and BI scores were 1.7-fold higher, in edaravone-treated patients vs. controls on day 14. Furthermore, the incidence of hemorrhage transformation, pulmonary infection, progressive stroke and epilepsy was markedly reduced in the edaravone vs. non-edaravone group.

CONCLUSION

Edaravone represents a promising neuroprotectant against cerebral ischemic injury in diabetic patients.

Protective Effect of Edaravone in Primary Cerebellar Granule Neurons against Iodoacetic Acid-Induced Cell Injury

Edaravone (EDA) is clinically used for treatment of acute ischemic stroke in Japan and China due to its potent free radical-scavenging effect. However, it has yet to be determined whether EDA can attenuate iodoacetic acid- (IAA-) induced neuronal death in vitro. In the present study, we investigated the effect of EDA on damage of IAA-induced primary cerebellar granule neurons (CGNs) and its possible underlying mechanisms. We found that EDA attenuated IAA-induced cell injury in CGNs. Moreover, EDA significantly reduced intracellular reactive oxidative stress production, loss of mitochondrial membrane potential, and caspase 3 activity induced by IAA. Taken together, EDA protected CGNs against IAA-induced neuronal damage, which may be attributed to its antiapoptotic and antioxidative activities.

Protective effect of edaravone against manganese-induced toxicity in cultured rat astrocytes

Manganese (Mn), a trace metal, is essential for maintaining the normal regulation of many biochemical and cellular processes. However, accumulation of Mn due to excessive environmental exposure leads to neurological impairment, referred to as manganism. Edaravone (EDA) is a potent free radical scavenger that has been clinically shown to reduce the neuronal injury after cerebral ischemia. In the present study, we aimed to examine the protective effects of EDA against Mn toxicity in astrocyte cultures. Astrocyte cultures were prepared from cerebral cortices of newborn Sprague-Dawley rats. The experiments were performed between 16 and 18 days of cultures. Astrocytes were treated in DMEM medium containing Mn (1-1000μM) for 24h to test Mn toxicity. In order to assess the effect of EDA, cells were pre-treated with different doses of EDA (10, 100 and 1000μM) 6h before Mn treatment. Cell viability (MTT), apoptotic cell death (Hoechst test) and lipid peroxide levels were evaluated in cultures. Our results showed that Mn significantly and dose-dependently reduced cell viability in astrocyte cultures. The apoptotic cell death and lipid peroxides were significantly higher in Mn treated cultures. Treatment of astrocytes with EDA successfully suppressed oxidative stress and cell death due to Mn exposure. The findings of the present study suggest that Mn cytotoxicity is mainly associated with ROS generation and apoptotic cell death. Besides, EDA may have beneficial effects against Mn toxicity. However, further studies are needed to elucidate the molecular mechanisms underlying protective effect of EDA.

Mitochondria: A Therapeutic Target for Parkinson's Disease?

Parkinson’s disease (PD) is one of the most common neurodegenerative disorders. The exact causes of neuronal damage are unknown, but mounting evidence indicates that mitochondrial-mediated pathways contribute to the underlying mechanisms of dopaminergic neuronal cell death both in PD patients and in PD animal models. Mitochondria are organized in a highly dynamic tubular network that is continuously reshaped by opposing processes of fusion and fission. Defects in either fusion or fission, leading to mitochondrial fragmentation, limit mitochondrial motility, decrease energy production and increase oxidative stress, thereby promoting cell dysfunction and death. Thus, the regulation of mitochondrial dynamics processes, such as fusion, fission and mitophagy, represents important mechanisms controlling neuronal cell fate. In this review, we summarize some of the recent evidence supporting that impairment of mitochondrial dynamics, mitophagy and mitochondrial import occurs in cellular and animal PD models and disruption of these processes is a contributing mechanism to cell death in dopaminergic neurons. We also summarize mitochondria-targeting therapeutics in models of PD, proposing that modulation of mitochondrial impairment might be beneficial for drug development toward treatment of PD.

Mitochondria-Targeted Protective Compounds in Parkinson's and Alzheimer's Diseases

Mitochondria are cytoplasmic organelles that regulate both metabolic and apoptotic signaling pathways; their most highlighted functions include cellular energy generation in the form of adenosine triphosphate (ATP), regulation of cellular calcium homeostasis, balance between ROS production and detoxification, mediation of apoptosis cell death, and synthesis and metabolism of various key molecules. Consistent evidence suggests that mitochondrial failure is associated with early events in the pathogenesis of ageing-related neurodegenerative disorders including Parkinson's disease and Alzheimer's disease. Mitochondria-targeted protective compounds that prevent or minimize mitochondrial dysfunction constitute potential therapeutic strategies in the prevention and treatment of these central nervous system diseases. This paper provides an overview of the involvement of mitochondrial dysfunction in Parkinson's and Alzheimer's diseases, with particular attention to in vitro and in vivo studies on promising endogenous and exogenous mitochondria-targeted protective compounds.

Neuroprotective effect of edaravone in experimental glaucoma model in rats: a immunofluorescence and biochemical analysis

AIM

To evaluate the neuroprotective activity of systemically administered edaravone in early and late stage of experimental glaucoma in rats.

METHODS

In this study, 60 Wistar albino rats were used. Experimental glaucoma model was created by injecting hyaluronic acid to the anterior chamber once a week for 6wk in 46 of 60 subjects. Fourteen subjects without any medication were included as control group. Edaravone administered intraperitoneally 3 mg/kg/d to the 15 of 30 subjects starting at the onset of glaucoma induction and also administered intraperitoneally 3 mg/kg/d to the other 15 subjects starting at three weeks after the onset of glaucoma induction. The other 16 subjects who underwent glaucoma induction was administered any therapy. Retinal ganglion cells (RGCs) have been marked with dextran tetramethylrhodamine (DTMR) retrograde at the end of the sixth week and after 48h, subjects were sacrificed by the method of cardiac perfusion. Alive RGC density was assessed in the whole-mount retina. Whole-mount retinal tissues homogenized and nitric oxide (NO), malondialdehyde (MDA) and total antioxidant capacity (TAC) values were measured biochemically.

RESULTS

RGCs counted with Image-Pro Plus program, in the treatment group were found to be statistically significantly protected, compared to the glaucoma group (Bonferroni, P<0.05). The neuroprotective activity of edaravone was found to be more influential by administration at the start of the glaucoma process. Statistically significant lower NO levels were determined in the glaucoma group comparing treatment groups (Bonferroni, P<0.05). MDA levels were found to be highest in untreated glaucoma group, TAC levels were found to be lower in the glaucoma induction groups than the control group (Bonferroni, P<0.05).

CONCLUSION

Systemic administration of Edaravone in experimental glaucoma showed potent neuroprotective activity. The role of oxidative stress causing RGC damage in glaucoma was supported by this study results.

N-acetylcysteine prevents rotenone-induced Parkinson's disease in rat: An investigation into the interaction of parkin and Drp1 proteins

There are convincing evidences that oxidative stress has an important role in both the initiation and progression of Parkinson's disease. N-acetylcysteine (NAC) is shown to have antioxidant properties via fortifying glutathione which is one of the main endogenous antioxidant systems. Therefore our study was aimed to evaluate the effect of NAC in management of Parkinson's disease. To this aim, male Wistar rats (10-12 months) received rotenone 2.5mg/kg/48 h intraperitoneally (ip) to induce a Parkinson's disease model. Pretreatment with NAC (25 and 50mg/kg/48 h ip) was administered 1h before the rotenone injection. Three behavioral tests (rotarod, rearing and bar tests) were performed for motor function assessment. Dopamine levels of dopaminergic areas in rat brain including substantia nigra (SN) and striatum (ST) were assessed using high performance liquid chromatography analysis to measure the loss of dopamine. Western blot analysis was also done for parkin and Drp1 (dynamin related protein-1) proteins quantification in SN and ST. Our results indicated that NAC significantly ameliorated the rotenone-induced motor dysfunction and dopamine loss. Furthermore, NAC was able to prevent the rotenone-induced changes in parkin and Drp1 levels in the both studied areas. In conclusion we found that NAC delayed the Parkinson's disease induction by rotenone and this effect might be related to its proved antioxidant effect.

Puerarin protects dopaminergic neurons in Parkinson's disease models

It has been acknowledged that oxidative stress, resulting in the apoptosis of dopaminergic neurons, is a key mechanism in the pathogenesis of Parkinson's disease (PD). Puerarin, extracted from the root of pueraria lobata, has been clinically used for ischemic heart disease and cerebrovascular diseases as an oxygen free radical scavenger. In this study, we aimed to explore the effect of puerarin on dopaminergic cell degeneration in vitro and in vivo and its possible underlying mechanisms. In SH-SY5Y cells, the reduction of cell viability, apoptosis rate and average DCFH-DA fluorescence intensity of puerarin-treated (0, 10, 50, 100 and 150 μM) cells were significantly lower than control group. In rotenone-based rodent models, puerarin treatment for 7 days ameliorated apomorphine-induced rotations significantly in Pue-50 and Pue-100 group by 45.65% and 53.06% in the first week, by 44.60% and 48.45% in the second week. Moreover, compared to control group, puerarin increased tyrosine hydroxylase (TH) expression in the substantia nigra by 85.52% and 84.26% in Pue-50 group and Pue-100 group, and upregulated the vesicular monoamine transporter 2 (VMAT2) by 41.24% in Pue-50 group and 35.20% in Pue-100 group, and decreased ubiquitin expression by 47.55% in Pue-50 group and 69.15% in Pue-100 group. These data indicated that puerarin alleviated the oxidative stress and apoptosis in a PD cellular model, protected the dopaminergic neurons against rotenone toxicity and decreased the abnormal protein overexpressing in PD animal models. These findings suggest that puerarin may develop into a neuroprotective alternative for patients with PD.

Melatonin inhibits manganese-induced motor dysfunction and neuronal loss in mice: involvement of oxidative stress and dopaminergic neurodegeneration

Excessive manganese (Mn) induces oxidative stress and dopaminergic neurodegeneration. However, the relationship between them during Mn neurotoxicity has not been clarified. The purpose of this study was to investigate the probable role of melatonin (MLT) against Mn-induced motor dysfunction and neuronal loss as a result of antagonizing oxidative stress and dopaminergic neurodegeneration. Mice were randomly divided into five groups as follows: control, MnCl2, low MLT + MnCl2, median MLT + MnCl2, and high MLT + MnCl2. Administration of MnCl2 (50 mg/kg) for 2 weeks significantly induced hypokinesis, dopaminergic neurons degeneration and loss, neuronal ultrastructural damage, and apoptosis in the substantia nigra and the striatum. These conditions were caused in part by the overproduction of reactive oxygen species, malondialdehyde accumulation, and dysfunction of the nonenzymatic (GSH) and enzymatic (GSH-Px, superoxide dismutase, quinone oxidoreductase 1, glutathione S-transferase, and glutathione reductase) antioxidative defense systems. Mn-induced neuron degeneration, astrocytes, and microglia activation contribute to the changes of oxidative stress markers. Dopamine (DA) depletion and downregulation of DA transporter and receptors were also found after Mn administration, this might also trigger motor dysfunction and neurons loss. Pretreatment with MLT prevented Mn-induced oxidative stress and dopaminergic neurodegeneration and inhibited the interaction between them. As a result, pretreatment with MLT significantly alleviated Mn-induced motor dysfunction and neuronal loss. In conclusion, Mn treatment resulted in motor dysfunction and neuronal loss, possibly involving an interaction between oxidative stress and dopaminergic neurodegeneration in the substantia nigra and the striatum. Pretreatment with MLT attenuated Mn-induced neurotoxicity by means of its antioxidant properties and promotion of the DA system.

Edaravone protected PC12 cells against MPP(+)-cytoxicity via inhibiting oxidative stress and up-regulating heme oxygenase-1 expression

Oxidative stress is involved in the pathogenesis of Parkinson's disease (PD). Edaravone has been shown to have a neuroprotective effect. In the present work, we investigated the effect of edaravone on 1-methyl-4-phenylpyridinium (MPP(+))-treated PC12 cells. Edaravone inhibited the decrease of cell viability and apoptosis induced by MPP(+) in PC12 cells. In addition, edaravone alleviated intracellular reactive oxygen species (ROS) production. MPP(+) induced heme oxygenase-1 (HO-1) expression, which was further enhanced by edaravone. The inhibitor of HO-1 zinc protoporphyrin-IX attenuated the neuroprotection of edaravone. So edaravone protected PC12 cells against MPP(+)-cytoxicity via inhibiting oxidative stress and up-regulating HO-1 expression. The data showed that edaravone was neuroprotective and could be potentially therapeutics for PD in future.

Edaravone mitigates hexavalent chromium-induced oxidative stress and depletion of antioxidant enzymes while estrogen restores antioxidant enzymes in the rat ovary in F1 offspring

Environmental contamination of drinking water with chromium (Cr) has been increasing in more than 30 cities in the United States. Previous studies from our group have shown that Cr affects reproductive functions in female Sprague Dawley rats. Although it is impossible to completely remove Cr from the drinking water, it is imperative to develop effective intervention strategies to inhibit Cr-induced deleterious health effects. Edaravone (EDA), a potential inhibitor of free radicals, has been clinically used to treat cancer and cardiac ischemia. This study evaluated the efficacy of EDA against Cr-induced ovarian toxicity. Results showed that maternal exposure to CrVI in rats increased follicular atresia, decreased steroidogenesis, and delayed puberty in F1 offspring. CrVI increased oxidative stress and decreased antioxidant (AOX) enzyme levels in the ovary. CrVI increased follicle atresia by increased expression of cleaved caspase 3, and decreased expression of Bcl2 and Bcl2l1 in the ovary. EDA mitigated or inhibited the effects of CrVI on follicle atresia, pubertal onset, steroid hormone levels, and AOX enzyme activity, as well as the expression of Bcl2 and Bcl2l1 in the ovary. In a second study, CrVI treatment was withdrawn, and F1 rats were injected with estradiol (E₂) (10 μg in PBS/ethanol per 100 g body weight) for a period of 2 wk to evaluate whether E₂ treatment will restore Cr-induced depletion of AOX enzymes. E₂ restored CrVI-induced depletion of glutathione peroxidase 1, catalase, thioredoxin 2, and peroxiredoxin 3 in the ovary. This is the first study to demonstrate the protective effects of EDA against any toxicant in the ovary.

Inhibitory effects of edaravone in β-amyloid-induced neurotoxicity in rats

Amyloid protein can damage nerve cells through a variety of biological mechanisms including oxidative stress, alterations in calcium homeostasis, and proapoptosis. Edaravone, a potent free radical scavenger possessing antioxidant effects, has been proved neuroprotective effect in stroke patients. The current study aimed to investigate the effects of EDA in an Aβ-induced rat model of AD, by studying Aβ_1–40-induced voltage-gated calcium channel currents in hippocampal CA1 pyramidal neurons, learning and memory behavioral tests, the number of surviving cholinergic neurons in the basal forebrain, and the acetylcholine level in the hippocampus in this rat model of AD. The results showed that the Aβ_1–40-induced increase of I_Ca can be inhibited by EDA in a dose-dependent manner. Treatment with EDA significantly improved Aβ_1–40-induced learning and memory performance. Choline acetyltransferase positive cells in basal forebrain and acetylcholine content in the hippocampus were increased by the administration of EDA as compared with the non-EDA treated Aβ_1–40 group. These results demonstrate that EDA can inhibit the neurotoxic effect of Aβ toxicity. Collectively, these findings suggest that EDA may serve as a potential complemental treatment strategy for AD.

Animal models of Parkinson's disease: a gateway to therapeutics?

Parkinson's disease (PD) is a progressive, neurodegenerative disorder of unknown etiology, although a complex interaction between environmental and genetic factors has been implicated as a pathogenic mechanism of selected neuronal loss. A better understanding of the etiology, pathogenesis, and molecular mechanisms underlying the disease process may be gained from research on animal models. While cell and tissue models are helpful in unraveling involved molecular pathways, animal models are much better suited to study the pathogenesis and potential treatment strategies. The animal models most relevant to PD include those generated by neurotoxic chemicals that selectively disrupt the catecholaminergic system such as 6-hydroxydopamine; 1-methyl-1,2,3,6-tetrahydropiridine; agricultural pesticide toxins, such as rotenone and paraquat; the ubiquitin proteasome system inhibitors; inflammatory modulators; and several genetically manipulated models, such as α-synuclein, DJ-1, PINK1, Parkin, and leucine-rich repeat kinase 2 transgenic or knock-out animals. Genetic and nongenetic animal models have their own unique advantages and limitations, which must be considered when they are employed in the study of pathogenesis or treatment approaches. This review provides a summary and a critical review of our current knowledge about various in vivo models of PD used to test novel therapeutic strategies.

Autophagy as an essential cellular antioxidant pathway in neurodegenerative disease

Oxidative stress including DNA damage, increased lipid and protein oxidation, are important features of aging and neurodegeneration suggesting that endogenous antioxidant protective pathways are inadequate or overwhelmed. Importantly, oxidative protein damage contributes to age-dependent accumulation of dysfunctional mitochondria or protein aggregates. In addition, environmental toxins such as rotenone and paraquat, which are risk factors for the pathogenesis of neurodegenerative diseases, also promote protein oxidation. The obvious approach of supplementing the primary antioxidant systems designed to suppress the initiation of oxidative stress has been tested in animal models and positive results were obtained. However, these findings have not been effectively translated to treating human patients, and clinical trials for antioxidant therapies using radical scavenging molecules such as α-tocopherol, ascorbate and coenzyme Q have met with limited success, highlighting several limitations to this approach. These could include: (1) radical scavenging antioxidants cannot reverse established damage to proteins and organelles; (2) radical scavenging antioxidants are oxidant specific, and can only be effective if the specific mechanism for neurodegeneration involves the reactive species to which they are targeted and (3) since reactive species play an important role in physiological signaling, suppression of endogenous oxidants maybe deleterious. Therefore, alternative approaches that can circumvent these limitations are needed. While not previously considered an antioxidant system we propose that the autophagy-lysosomal activities, may serve this essential function in neurodegenerative diseases by removing damaged or dysfunctional proteins and organelles.

•

Significant oxidative damage occurs in neurodegenerative disease brains.

•

Effective in animal models with single toxins, antioxidants are ineffective in clinical trials.

•

The failure of antioxidant therapy maybe due to propagation of cellular damage.

•

Autophagic clearance of diverse damaged molecules may provide antioxidant mechanisms.

•

Further mechanistic and translational studies on autophagy therapy are needed.