Oxidative stress and apoptosis in neurodegeneration

Unveiling the Journey from the Gut to the Brain: Decoding Neurodegeneration-Gut Connection in Parkinson's Disease

Parkinson's disease, a classical motor disorder affecting the dopaminergic system of the brain, has been as a disease of the brain, but this classical notion has now been viewed differently as the pathology begins in the gut and then gradually moves up to the brain regions. The microorganisms in the gut play a critical role in maintaining the physiology of the gut from maintaining barrier integrity to secretion of microbial products that maintain a healthy gut state. The pathology subsequently alters the normal composition of gut microbes and causes deleterious effects that ultimately trigger strong neuroinflammation and nonmotor symptoms along with characteristic synucleopathy, a pathological hallmark of the disease. Understanding the complex pathomechanisms in distinct and established preclinical models is the primary goal of researchers to decipher how exactly gut pathology has a central effect; the quest has led to many answered and some open-ended questions for researchers. We summarize the popular opinions and some contrasting views, concise footsteps in the treatment strategies targeting the gastrointestinal system.

Targeting inflammation and oxidative stress for protection against ischemic brain injury in rats using cupressuflavone

Inflammatory responses and oxidative stress contribute to the pathogenesis of brain ischemia/reperfusion (IR) injury. Naturally occurring bioflavonoids possess antioxidant and anti-inflammatory properties. The phytochemicals of Juniperus sabina L., known as "Abhal" in Saudi Arabia, have been studied and cupressuflavone (CUP) has been isolated as the major bioflavonoid. This study aimed to investigate the neuroprotective potential of CUP in reducing brain IR damage in rats and to understand probable mechanisms. After 60 min of inducing cerebral ischemia by closing the left common carotid artery (CCA), blood flow was restored to allow reperfusion. The same surgical procedure was performed on sham-operated control rats, excluding cerebral IR. CUP or vehicle was given orally to rats for 3 days prior to ischemia induction and for a further 3 days following reperfusion. Based on the findings of this study, compared to the IR control group, CUP-administered group demonstrated reduced neurological deficits, improved motor coordination, balance, and locomotor activity. Additionally, brain homogenates of IR rats showed a decrease in malondialdehyde (MDA) level, an increase in reduced glutathione (GSH) content, and an increase in catalase (CAT) enzyme activity following CUP treatment. CUP suppressed neuro-inflammation via reducing serum inflammatory cytokine levels, particularly those of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) and enhancing the inflammatory cytokine levels, such as Nuclear factor kappa- B (NF-κB), TANK-binding kinase-1 (TBK1), and interferon beta (IFN-β) in brain tissues. Furthermore, CUP ameliorated the histological alterations in the brain tissues of IR rats. CUP significantly suppressed caspase-3 expression and downregulated the Toll-like receptor 4 (TLR4)/NF-κB signaling pathway as a result of suppressing High mobility group box 1 (HMGB1). To our knowledge, this is the first study to document the neuroprotective properties of CUP. Thus, the study findings revealed that CUP ameliorates IR-induced cerebral injury possibly by enhancing brain antioxidant contents, reducing serum inflammatory cytokine levels, potentiating the brain contents of TBK1 and IFN-β and suppressing the HMGB1/TLR-4 signaling pathway. Hence, CUP may serve as a potential preventive and therapeutic alternative for cerebral stroke.

The effects of myricitrin and chebulinic acid on the rat hippocampus exposed to gamma radiation: A stereological, histochemical and biochemical study

AIM

Gamma radiation, a form of ionizing radiation, is used in many different areas, especially in the health field and in the treatment of cancer. However, gamma radiation used for therapeutic purposes also has numerous harmful effects on human health. This study was planned to investigate the impacts of exposure to gamma radiation on the hippocampal area and the preventive effects of myricitrin and chebulinic acid against that damage.

MATERIAL AND METHOD

Thirty-six male Wistar albino rats were randomly divided into six groups. The control group was exposed to no treatment. The chebulinic acid and myricitrin groups were injected with the relevant drug at a dosage of 0.033 mg/kg) (vehicle; normal saline) per day. The gamma groups were placed in a plexiglass test setup with their heads positioned close to the source. The subjects were exposed to radiation with a mixed source containing radioactive Cs-137 and Co-60 isotopes obtained from Ondokuz Mayıs University Physics Department Nuclear Physics Laboratory for 1 h. Gamma radiation was applied 16 mGy for one hour per day for 10 days. The gamma radiation+chebulinic acid and the gamma radiation myricitrin groups also received 0.033 mg/kg per day of these drugs via injection. Immediately after the experimental procedure, all animals were subjected to behavioural tests, and perfused brain tissues were analyzed using stereological methods.

RESULTS

Stereological analysis showed that gamma radiation caused a decrease in the numbers of neurons in the hippocampal area (p < 0.01; One-way ANOVA) and that chebulinic acid and myricitrin reduced this decrease (p < 0.01; One-way ANOVA). Decreases in learning and memory capacity were detected in behavioural tests in rats from the Gamma group.

CONCLUSION

The study findings showed that that the adverse health effects of Gamma radiation can be ameliorated using myricitrin and chebulinic acid. Myricitrin was more effective in terms of cell proliferation and defence against oxidative stress than chebulinic acid, and exhibited a more neuroprotective effect. However, more detailed analyses should be performed before using either antioxidant for therapeutic purposes.

Cerebral hemodynamic and metabolic dysregulation in the postradiation brain

Technological advances in the delivery of radiation and other novel cancer therapies have significantly improved the 5-year survival rates over the last few decades. Although recent developments have helped to better manage the acute effects of radiation, the late effects such as impairment in cognition continue to remain of concern. Accruing data in the literature have implicated derangements in hemodynamic parameters and metabolic activity of the irradiated normal brain as predictive of cognitive impairment. Multiparametric imaging modalities have allowed us to precisely quantify functional and metabolic information, enhancing the anatomic and morphologic data provided by conventional MRI sequences, thereby contributing as noninvasive imaging-based biomarkers of radiation-induced brain injury. In this review, we have elaborated on the mechanisms of radiation-induced brain injury and discussed several novel imaging modalities, including MR spectroscopy, MR perfusion imaging, functional MR, SPECT, and PET that provide pathophysiological and functional insights into the postradiation brain, and its correlation with radiation dose as well as clinical neurocognitive outcomes. Additionally, we explored some innovative imaging modalities, such as quantitative blood oxygenation level-dependent imaging, susceptibility-based oxygenation measurement, and T2-based oxygenation measurement, that hold promise in delineating the potential mechanisms underlying deleterious neurocognitive changes seen in the postradiation setting. We aim that this comprehensive review of a range of imaging modalities will help elucidate the hemodynamic and metabolic injury mechanisms underlying cognitive impairment in the irradiated normal brain in order to optimize treatment regimens and improve the quality of life for these patients.

A review on neurodegenerative diseases associated with oxidative stress and mitochondria

Alzheimer's disease, Parkinson's disease, and other neurological diseases afflict people of all ages. Neuronal loss and cognitive dysfunction are common symptoms of these disorders. Overproduction of reactive oxygen species has been demonstrated to aggravate disease progression in previous investigations (ROS). Because of the large quantities of polyunsaturated fatty acids in their membranes and their fast oxygen consumption rate, neurons are especially susceptible to oxidative damage. The molecular aetiology of neurodegeneration produced by changes in redox balance has not yet been established. New antioxidants have shown considerable potential in modifying disease characteristics. For the treatment of Alzheimer's disease and other neurodegenerative illnesses such as Parkinson's disease, ALS and spinocerebellar ataxia and Huntington's disease, antioxidant-based therapies are examined extensively in the literature.

Hydrolase-Treated Royal Jelly Attenuates H2O2- and Glutamate-Induced SH-SY5Y Cell Damage and Promotes Cognitive Enhancement in a Rat Model of Vascular Dementia

Vascular dementia (VaD) is the second most common type of dementia following Alzheimer's disease, but the therapeutic efficacy is still not effective. This makes the searching for novel neuroprotective agents important. Therefore, we hypothesized that royal jelly, a well-known traditional medicine, could attenuate memory impairment and brain damage in vascular dementia. This study determined the effects of royal jelly hydrolysate (RJH) and possible mechanism of cell damage and cognitive-enhancing effect in animal study. An in vitro study assessed the effects of RJH on acetylcholinesterase inhibitor, cell viability, and cell damage in SH-SY5Y neuroblastoma cells. Then, an in vivo study examined vascular dementia by the occlusion of the right middle cerebral artery (Rt.MCAO); adult male Wistar rats had been orally given RJH at doses ranging from 10, 50, to 100 mg/kg for 14 days before and 14 days after the occlusion of Rt.MCAO to mimic the VaD condition. Rats' spatial memory was evaluated using Morris water maze and radial arm maze every 7 days after Rt.MCAO throughout a 14-day experimental period, and then, they were sacrificed and the acetylcholinesterase (AChE) activity in the hippocampus was determined. The results showed that RJH has no cytotoxic effect with the final concentration up to 500 μg protein/ml and reduces cell death from the H₂O₂- and glutamate-induced cell damage in in vitro neuroblastoma cells. Importantly, RJH significantly improved memory performance in Morris water maze test and radial arm maze and decreased the level of acetyl cholinesterase activity. In conclusion, RJH is the potential neuroprotective agent and cognitive enhancer for VaD.

Identification of Multi-Target Anti-AD Chemical Constituents From Traditional Chinese Medicine Formulae by Integrating Virtual Screening and In Vitro Validation

Alzheimer's disease (AD) is a neurodegenerative disease that seriously threatens the health of the elderly. At present, no drugs have been proven to cure or delay the progression of the disease. Due to the multifactorial aetiology of this disease, the multi-target-directed ligand (MTDL) approach provides an innovative and promising idea in search for new drugs against AD. In order to find potential multi-target anti-AD drugs from traditional Chinese medicine (TCM) formulae, a compound database derived from anti-AD Chinese herbal formulae was constructed and predicted by the anti-AD multi-target drug prediction platform established in our laboratory. By analyzing the results of virtual screening, 226 chemical constituents with 3 or more potential AD-related targets were collected, from which 16 compounds that were predicted to combat AD through various mechanisms were chosen for biological validation. Several cell models were established to validate the anti-AD effects of these compounds, including KCl, Aβ, okadaic acid (OA), SNP and H₂O₂ induced SH-SY5Y cell model and LPS induced BV2 microglia model. The experimental results showed that 12 compounds including Nonivamide, Bavachromene and 3,4-Dimethoxycinnamic acid could protect model cells from AD-related damages and showed potential anti-AD activity. Furthermore, the potential targets of Nonivamide were investigated by molecular docking study and analysis with CDOCKER revealed the possible binding mode of Nonivamide with its predicted targets. In summary, 12 potential multi-target anti-AD compounds have been found from anti-AD TCM formulae by comprehensive application of computational prediction, molecular docking method and biological validation, which laid a theoretical and experimental foundation for in-depth study, also providing important information and new research ideas for the discovery of anti-AD compounds from traditional Chinese medicine.

Advances in Activity-Based Sensing Probes for Isoform-Selective Imaging of Enzymatic Activity

Until recently, there were no generalizable methods for assessing the effects of post-translational regulation on enzymatic activity. Activity-based sensing (ABS) has emerged as a powerful approach for monitoring small-molecule and enzyme activities within living systems. Initial examples of ABS were applied for measuring general enzymatic activity; however, a recent focus has been placed on increasing the selectivity to monitor a single enzyme or isoform. The highest degree of selectivity is required for differentiating between isoforms, where the targets display significant structural similarities as a result of a gene duplication or alternative splicing. This Minireview highlights key examples of small-molecule isoform-selective probes with a focus on the relevance of isoform differentiation, design strategies to achieve selectivity, and applications in basic biology or in the clinic.

Peroxynitrite-induced conformational changes in DNA that lead to cell death: UV, CD spectral, molecular dynamics simulation and FACS analysis

Peroxynitrite is known to react with biomolecules leading to their structural and function alteration. Structural alteration in DNA induced by peroxynitrite is not clearly known. The current study was carried out to decipher the changes induced by peroxynitrite using UV-Vis spectra, circular dichrometry, molecular dynamics simulation followed by restriction digestion. Apoptotic markers Bax, Bcl-2 and caspase genes were also studied by FACS in peroxynitrite induced PC12 cells. The results obtained showed that PXN binds to DNA leading to hyperchromicity of DNA in the presence of PXN over a period of time and the same was established by In silico studies where PXN modifies the DNA to accommodate itself into the stacking and brings about the significant structural alterations. Further, FACS studies reveal that Bcl-2 gene expression was down regulated whereas BAXand caspase genes were up regulated compared to control concluding that PXN induces apoptotic cell death in PC12 cells.

Mitochondrial-Targeted and Near-Infrared Fluorescence Probe for Bioimaging and Evaluating Monoamine Oxidase A Activity in Hepatic Fibrosis

Monoamine oxidase A (MAO-A) is a promising diagnostic marker for cancer, depression, Parkinson's disease, and liver disease. The fluorescence detection of MAO-A in living animals is of extreme importance for the early diagnosis of related diseases. However, the development of specific and mitochondrial-targeted and near-infrared (NIR) fluorescence MAO-A probes is still inadequate. Here, we designed and synthesized four NIR fluorescence probes containing a dihydroxanthene (DH) skeleton to detect MAO-A in complex biological systems. The specificity of our representative probe DHMP2 displays a 31-fold fluorescence turn-on in vitro, and it can effectively accumulate in the mitochondria and specifically detect the endogenous MAO-A concentrations in PC-3 and SH-SY5Y cell lines. Furthermore, the probe DHMP2 can be used to visualize the endogenous MAO-A activity in zebrafish and tumor-bearing mice. More importantly, it is the first time that the MAO-A activity of hepatic fibrosis tissues is detected through the probe DHMP2. The present study shows that the synthesized DHMP2 might serve as a potential tool for monitoring MAO-A activity in vivo and diagnosing related diseases.

PAK2 activated by Cdc42 and caspase 3 mediates different cellular responses to oxidative stress-induced apoptosis

p21-activated protein kinase (PAK2) is a unique member of the PAK family kinases that plays important roles in stress signaling. It can be activated by binding to the small GTPase, Cdc42 and Rac1, or by caspase 3 cleavage. Cdc42-activated PAK2 mediates cytostasis, whereas caspase 3-cleaved PAK2 contributes to apoptosis. However, the relationship between these two states of PAK2 activation remains elusive. In this study, through protein biochemical analyses and various cell-based assays, we demonstrated that full-length PAK2 activated by Cdc42 was resistant to the cleavage by caspase 3 in vitro and within cells. When mammalian cells were treated by oxidative stress using hydrogen peroxide, PAK2 was highly activated through caspase 3 cleavage that led to apoptosis. However, when PAK2 was pre-activated by Cdc42 or by mild stress such as serum deprivation, it was no longer able to be cleaved by caspase 3 upon hydrogen peroxide treatment, and the subsequent apoptosis was also largely inhibited. Furthermore, cells expressing active mutants of full-length PAK2 became more resistant to hydrogen peroxide-induced apoptosis than inactive mutants. Taken together, this study identified two states of PAK2 activation, wherein Cdc42- and autophosphorylation-dependent activation inhibited the constitutive activation of PAK2 by caspase cleavage. The regulation between these two states of PAK2 activation provides a new molecular mechanism to support PAK2 as a molecular switch for controlling cytostasis and apoptosis in response to different types and levels of stress with broad physiological and pathological relevance.

The Methanol Extract of Allium cepa L. Protects Inflammatory Markers in LPS-Induced BV-2 Microglial Cells and Upregulates the Antiapoptotic Gene and Antioxidant Enzymes in N27-A Cells

Neuroinflammation, apoptosis, and oxidative stress are connected to the pathogenesis of neurodegenerative diseases (NDDs). Targeting these three factors, the intervention of neuroprotective agents may have great potential in the treatment of NDDs. In the current study, the anti-inflammatory effects of the methanol extract of Allium cepa (MEAC) in lipopolysaccharide (LPS)-induced BV-2 microglial cells were investigated. MEAC has been studied in regard to the regulation of the antiapoptotic gene (Bcl-2) and various antioxidant enzyme (HO-1, NQO-1, and catalase) expressions in N27-A cells. Additionally, the protective action of MEAC has also been studied against MPP⁺-induced death in N27-A cells. The results suggest that MEAC is significantly protected from NO release and increase iNOS expression at the mRNA and protein levels in LPS-stimulated BV-2 microglial cells. MEAC treatment also protects COX-2 expression at the mRNA and protein levels. Furthermore, MEAC treatment prevents LPS-stimulated increases of proinflammatory cytokines, including TNF-α, IL-6, and IL-1β. In N27-A cells, MEAC treatment significantly upregulates antiapoptotic gene (Bcl-2) and antioxidant enzyme (HO-1, NQO1, and catalase) expressions. Moreover, MEAC treatment protects against MPP⁺-induced death in N27-A cells. To conclude, A cepa extract takes protective action against LPS and MPP⁺, and upregulates the antioxidant enzymes that could potentially be used in the therapy of NDDs.

Artemisinin Attenuated Hydrogen Peroxide (H2O2)-Induced Oxidative Injury in SH-SY5Y and Hippocampal Neurons via the Activation of AMPK Pathway

Oxidative stress is believed to be one of the main causes of neurodegenerative diseases such as Alzheimer’s disease (AD). The pathogenesis of AD is still not elucidated clearly but oxidative stress is one of the key hypotheses. Here, we found that artemisinin, an anti-malarial Chinese medicine, possesses neuroprotective effects. However, the antioxidative effects of artemisinin remain to be explored. In this study, we found that artemisinin rescued SH-SY5Y and hippocampal neuronal cells from hydrogen peroxide (H₂O₂)-induced cell death at clinically relevant doses in a concentration-dependent manner. Further studies showed that artemisinin significantly restored the nuclear morphology, improved the abnormal changes in intracellular reactive oxygen species (ROS), reduced the mitochondrial membrane potential, and caspase-3 activation, thereby attenuating apoptosis. Artemisinin also stimulated the phosphorylation of the adenosine monophosphate -activated protein kinase (AMPK) pathway in SH-SY5Y cells in a time- and concentration-dependent manner. Inhibition of the AMPK pathway attenuated the protective effect of artemisinin. These data put together suggested that artemisinin has the potential to protect neuronal cells. Similar results were obtained in primary cultured hippocampal neurons. Cumulatively, these results indicated that artemisinin protected neuronal cells from oxidative damage, at least in part through the activation of AMPK. Our findings support the role of artemisinin as a potential therapeutic agent for neurodegenerative diseases.

Identification of differentially expressed proteins in Ostrinia furnacalis adults after exposure to ultraviolet A

Ultraviolet A (UVA), the major component of solar UV irradiation, is an important environmental factor inducing damage to insects including cell death, photoreceptor damage, and oxidative stress. In order to improve understanding of the adaptation mechanisms of insect after UVA exposure, a comparative proteomic analysis was carried out to reveal differential protein expression in Ostrinia furnacalis. Three-day-old adults were treated with UVA for 1 h. Total proteins of control and UVA-treated insects were examined using two-dimensional electrophoresis (2-DE). 2-DE analysis demonstrated that 19 proteins were increased and 18 proteins were decreased significantly in O. furnacalis after UVA exposure, respectively. Thirty differentially expressed proteins were successfully identified by mass spectrometry. The identified proteins were involved in diverse biological processes, such as signal transduction, transport processing, cellular stress, metabolisms, and cytoskeleton organization. Our results reveal that the response patterns of O. furnacalis to UVA irradiation are complex and provide novel insights into the adaptation response to UVA irradiation stress.

Neuroprotective effects of Quercetin on radiation-induced brain injury in rats

Extensive research has been focused on radiation-induced brain injury. Animal and human studies have shown that flavonoids have remarkable toxicological profiles. This study aims to investigate the neuroprotective effects of quercetin in an experimental radiation-induced brain injury. A total of 32 adult male Wistar-Albino rats were randomly divided into four groups (control, quercetin, radiation, and radiation+quercetin groups, with eight rats in each group). Doses (50 mg/kg) of quercetin were administered to the animals in the quercetin and radiation+quercetin groups; radiation and radiation+quercetin groups were exposed to a dose of 20 Gy to the cranium region. Tissue samples, and biochemical levels of tissue injury markers in the four groups were compared. In all measured parameters of oxidative stress, administration of quercetin significantly demonstrated favorable effects. Both plasma and tissue levels of malondialdehyde and total antioxidant status significantly changed in favor of antioxidant activity. Histopathological evaluation of the tissues also demonstrated a significant decrease in cellular degeneration and infiltration parameters after quercetin administration. Quercetin demonstrated significant neuroprotection after radiation-induced brain injury. Further studies of neurological outcomes under different experimental settings are required in order to achieve conclusive results.

Acer okamotoanum protects SH-SY5Y neuronal cells against hydrogen peroxide-induced oxidative stress

Oxidative stress by over-production of reactive oxygen species (ROS) in brain is widely known as a cause of neurodegenerative disease. We investigated protective effects of Acer okamotoanum against oxidative stress by hydrogen peroxide (H₂O₂) in SH-SY5Y neuronal cells. Acer okamotoanum reduced ROS production and lactate dehydrogenase release in H₂O₂-induced SH-SY5Y cells, resulting in elevation of cell viability. To elucidate protective mechanisms, we measured inflammation and apoptosis-associated protein expressions. Treatment with A. okamotoanum dose-dependently decreased pro-inflammatory proteins such as inducible nitric oxide synthase and cyclooxygenase-2. Treatment with A. okamotoanum showed down-regulation of pro-apoptosis genes such as cleaved caspase-3, cleaved caspase-9, and Bax, and up-regulation of anti-apoptosis protein including Bcl-2, in H₂O₂-induced SH-SY5Y cells. We demonstrated potential anti-inflammatory and anti-apoptotic effect of A. okamotoanum in H₂O₂-induced SH-SY5Y cells. These results suggest that A. okamotoanum may possess neuroprotective potential, but further study is necessary to elucidate its pharmacological effects in neurodegenerative diseases.

Electrochemical Hydrogen Peroxide Sensor Based on Macroporous Silicon

Macroporous silicon was prepared through an anodization process; the prepared samples showed an average pore size ranging from 4 to 6 microns, and the depth of the pores in the silicon wafer was approximately 80 microns. The prepared samples were tested for hydrogen peroxide (H₂O₂) concentrations, which can be used for industrial and environmental sensing applications. The selected H₂O₂ concentration covered a wide range from 10 to 5000 μM. The tested samples showed a linear response through the tested H₂O₂ concentrations with a sensitivity of 0.55 μA μM^-1∙cm^-2 and lower detection limits of 4.35 μM at an operating voltage of 5 V. Furthermore, the electrode exhibited a rapid response with a response time of ca. two seconds. Furthermore, the prepared sensor showed a reasonable stability over a one-month time period.

Melandrii Herba Extract Attenuates H₂O₂-Induced Neurotoxicity in Human Neuroblastoma SH-SY5Y Cells and Scopolamine-Induced Memory Impairment in Mice

Oxidative stress plays a significant role in the etiology of a variety of neurodegenerative diseases. In this study, we found that Melandrii Herba extract (ME) attenuated oxidative-induced damage in cells. Mechanistically, ME exhibited protection from H₂O₂-induced neurotoxicity via caspase-3 inactivation, Bcl-2 downregulation, Bax upregulation, and MAPK activation (ERK 1/2, JNK 1/2, and p38 MAPK) in vitro. Moreover, our in vivo data showed that ME was able to attenuate scopolamine-induced cognitive impairment. These results provide in vitro and in vivo evidence that ME exhibits neuroprotective properties against oxidative stress, which suggests that ME is worthy of further investigation as a complementary, or even as an alternative, product for preventing and treating neurodegenerative disorders.

Chicoric acid supplementation ameliorates cognitive impairment induced by oxidative stress via promotion of antioxidant defense system

Illustration of effects of chicoric acid on neuroprotection againstd-gal-induced memory impairmentviainflammation and oxidative stress.

The Neuro-Protective Effect of the Methanolic Extract of Perilla frutescens var. japonicaand Rosmarinic Acid against H₂O₂-Induced Oxidative Stress in C6 Glial Cells

Neurodegenerative diseases are often associated with oxidative damage in neuronal cells. This study was conducted to investigate the neuro-protective effect of methanolic (MeOH) extract of Perilla frutescens var. japonica and its one of the major compounds, rosmarinic acid, under oxidative stress induced by hydrogen peroxide (H₂O₂) in C6 glial cells. Exposure of C6 glial cells to H₂O₂ enhanced oxidative damage as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and thiobarbituric acid-reactive substance assays. The MeOH extract and rosmarinic acid prevented oxidative stress by increasing cell viability and inhibiting cellular lipid peroxidation. In addition, the MeOH extract and rosmarinic acid reduced H₂O₂-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the transcriptional level. Moreover, iNOS and COX-2 protein expression was down-regulated in H₂O₂-indcued C6 glial cells treated with the MeOH extract and rosmarinic acid. These findings suggest that P. frutescens var. japonica and rosmarinic acid could prevent the progression of neurodegenerative diseases through attenuation of neuronal oxidative stress.

Quantitative proteomics study of the neuroprotective effects of B12 on hydrogen peroxide-induced apoptosis in SH-SY5Y cells

B12 belongs to the coumarin class of compounds that have been shown to have various physiological and pharmacological activities including anti-inflammatory, antibacterial, and antioxidant. In the present study, we characterised the neuroprotective effects of B12 against H₂O₂-induced neuronal cell damage in SH-SY5Y cells. Protein expression profiling in combination with pathway analysis was deployed to investigate the molecular events associated with the neuroprotective effects in human neuronal cells using a label-free quantitative proteomics approach. A total of 22 proteins were significantly differentially expressed in H₂O₂-damaged cells with or without B12 treatment. Bioinformatics analysis using the Cytoscape platform indicated that poly pyrimidine tract binding protein 1 (PTBP1) was highly associated with the protective effect, and western blotting verified that PTBP1 was up-regulated in H₂O₂ + B12 treatment group, compared with the H₂O₂ treated group. PTBP RNAi experiments knocked down PTBP expression, which cancelled out the protective effect of B12 on cell viability. Thus, we infer that B12 neuroprotective activity involves up-regulation of PTBP1 and its associated signalling networks following H₂O₂-induced apoptosis in SH-SY5Y cells. B12 or related compounds may prove to be useful therapeutic agents for the treatment of neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

Neuroprotective and antioxidant activities of bamboo salt soy sauce against H2O2-induced oxidative stress in rat cortical neurons

Bamboo salt (BS) and soy sauce (SS) are traditional foods in Asia, which contain antioxidants that have cytoprotective effects on the body. The majority of SS products contain high levels of common salt, consumption of which has been associated with numerous detrimental effects on the body. However, BS may be considered a healthier substitute to common salt. The present study hypothesized that SS made from BS, known as bamboo salt soy sauce (BSSS), may possess enhanced cytoprotective properties; this was evaluated using a hydrogen peroxide (H₂O₂)-induced neuronal cell death rat model. Rat neuronal cells were pretreated with various concentrations (0.001, 0.01, 0.1, 1 and 10%) of BSSS, traditional soy sauce (TRSS) and brewed soy sauce (BRSS), and were subsequently exposed to H₂O₂ (100 µM). The viability of neuronal cells, and the occurrence of DNA fragmentation, was subsequently examined. Pretreatment of neuronal cells with TRSS and BRSS reduced cell viability in a concentration-dependent manner, whereas neuronal cells pretreated with BSSS exhibited increased cell viability, as compared with non-treated neuronal cells. Furthermore, neuronal cells pretreated with 0.01% BSSS exhibited the greatest increase in viability. Exposure of neuronal cells to H₂O₂ significantly increased the levels of reactive oxygen species (ROS), B-cell lymphoma 2-associated X protein, poly (ADP-ribose), cleaved poly (ADP-ribose) polymerase, cytochrome c, apoptosis-inducing factor, cleaved caspase-9 and cleaved caspase-3, in all cases. Pretreatment of neuronal cells with BSSS significantly reduced the levels of ROS generated by H₂O₂, and increased the levels of phosphorylated AKT and phosphorylated glycogen synthase kinase-3β. Furthermore, the observed effects of BSSS could be blocked by administration of 10 µM LY294002, a phosphatidylinositol 3-kinase inhibitor. The results of the present study suggested that BSSS may exert positive neuroprotective effects against H₂O₂-induced cell death by reducing oxidative stress, enhancing survival signaling, and inhibiting death signals.

Time-Course Analysis of Protein and Lipid Oxidation in the Brains of Yac128 Huntington's Disease Transgenic Mice

Huntington's disease (HD) is caused by an expansion of cytosine-adenine-guanine (CAG) repeats within the coding region of the HD gene, which expresses the protein huntingtin and is characterized by selective degeneration of specific neuronal populations, mainly in the striatum and the cortex. The mechanisms that account for this selective neuronal death are multifaceted, but oxidative stress might play an important role in this process. To determine whether changes in the intracellular redox state will result in oxidative damage to cellular macromolecules with disease progression, we analyzed levels of lipid peroxidation (with the thiobarbituric acid reactive substances [TBARS] assay) and protein carbonyl formation (using the 2,4-dinitrophenylhydrazine reaction) in the cerebellum, cerebral cortex, prefrontal cortex, striatum, and hippocampus of the YAC128 HD mouse model at 3, 6, and 12 months of age. With the exception of a transient increase in protein carbonyl levels in the YAC128 prefrontal cortex at 6 months of age, levels of lipid peroxidation and protein oxidation were not significantly different between YAC128 mice and their age-matched wild-type counterparts in any of the brain regions analyzed up to 12 months of age. However, age-related increases in oxidative stress were observed in various brain regions. These results suggest that lipid and protein oxidative damage is not a major contributor to neurodegeneration in the YAC128 brain up to 12 months of age.

Light-Up Probes Based on Fluorogens with Aggregation-Induced Emission Characteristics for Monoamine Oxidase-A Activity Study in Solution and in Living Cells

Fluorogens with aggregation-induced emission (AIEgens) have emerged as a powerful and versatile platform for the development of novel biosensors. In this study, a series of water-soluble fluorescent probes based on tetraphenylethylene (TPE) were designed and synthesized for the detection of monoamine oxidases (MAOs) based on specific interactions between the probes and the proteins. Among the six probes developed, t-TPEM displays a significant fluorescence increase upon introduction of MAOs. Of particular significance is that the fluorescence of t-TPEM in the presence of MAO-A is 21-fold higher than other proteins including MAO-B. Lineweaver-Burk plots reveal that t-TPEM acts as an uncompetitive inhibitor of MAO-A with Ki = 17.1 μM, which confirms its good binding affinity toward MAO-A. Furthermore, a cell imaging experiment reveals that t-TPEM is able to selectively monitor the activity of MAO-A which is localized in mitochondria of MCF-7 cells.

Assessment of C-phycocyanin effect on astrocytes-mediated neuroprotection against oxidative brain injury using 2D and 3D astrocyte tissue model

Drugs are currently being developed to attenuate oxidative stress as a treatment for brain injuries. C-phycocyanin (C-Pc) is an antioxidant protein of green microalgae known to exert neuroprotective effects against oxidative brain injury. Astrocytes, which compose many portions of the brain, exert various functions to overcome oxidative stress; however, little is known about how C-Pc mediates the antioxidative effects of astrocytes. In this study, we revealed that C-Pc intranasal administration to the middle cerebral artery occlusion (MCAO) rats ensures neuroprotection of ischemic brain by reducing infarct size and improving behavioral deficits. C-Pc also enhanced viability and proliferation but attenuated apoptosis and reactive oxygen species (ROS) of oxidized astrocytes, without cytotoxicity to normal astrocytes and neurons. To elucidate how C-Pc leads astrocytes to enhance neuroprotection and repair of ischemia brain, we firstly developed 3D oxidized astrocyte model. C-Pc had astrocytes upregulate antioxidant enzymes such as SOD and catalase and neurotrophic factors BDNF and NGF, while alleviating inflammatory factors IL-6 and IL-1β and glial scar. Additionally, C-Pc improved viability of 3D oxidized neurons. In summary, C-Pc was concluded to activate oxidized astrocytes to protect and repair the ischemic brain with the combinatorial effects of improved antioxidative, neurotrophic, and anti-inflammatory mechanisms.

Expression profile of six stress-related genes and productive performances of fast and slow growing broiler strains reared under heat stress conditions

High temperature is one of the prominent environmental factors causing economic losses to the poultry industry as it negatively affects growth and production performance in broiler chickens. We used One Step TaqMan real time RT-PCR (reverse transcription polymerase chain reaction) technology to study the effects of chronic heat stress on the expression of genes codifying for the antioxidative enzymes superoxide dismutase (SOD), and catalase (CAT), as well as for heat shock protein (HSP) 70, HSP90, glucocorticoid receptor (NR3C1), and caspase 6 (CASP6) in the liver of two different broiler genetic strains: Red JA Cou Nu Hubbard (CN) and Ross 508 Aviagen (RO). CN is a naked neck slow growing broiler intended for the free range and/or organic markets, whereas RO is selected for fast growing. We also analysed the effect of chronic heat stress on productive performances, and plasma corticosterone levels as well as the association between transcriptomic response and specific SNPs (single nucleotide polymorphisms) in each genetic strain of broiler chickens. RO and CN broilers, 4 weeks of age, were maintained for 4 weeks at either 34 °C or 22 °C. The results demonstrated that there was a genotype and a temperature main effect on the broilers' growth from the 4th to the 8th week of age, but the interaction effect between genotype and temperature resulted not statistically significant. By considering the genotype effect, fast growing broilers (RO) grew more than the slow growing ones (CN), whereas by considering the temperature effect, broilers in unheated conditions grew more than the heat stressed ones. Corticosterone levels increased significantly in the blood of heat stressed broilers, due to the activation of the HPA (hypothalamic-pituitary-adrenocortical axis). Carcass yield at slaughter was of similar values in the 4 cohorts (genotype/temperature combinations or treatment groups), ranging from 86.5 to 88.6%, whereas carcass weight was negatively influenced by heat stress in both broiler strains. Heat stress affected gene expression by downregulating CASP6 and upregulating CAT transcript levels. HSPs, SOD and NR3C1 mRNA levels remained unaffected by heat stress. The differences found in the mRNA copies of CASP6 gene could be partly explained by SNPs.

The Neuroprotective Effects of Ratanasampil on Oxidative Stress-Mediated Neuronal Damage in Human Neuronal SH-SY5Y Cells

We previously found that Ratanasampil (RNSP), a traditional Tibetan medicine, improves the cognitive function of mild-to-moderate AD patients living at high altitude, as well as learning and memory in an AD mouse model (Tg2576); however, mechanism underlying the effects of RNSP is unknown. In the present study, we investigated the effects and molecular mechanisms of RNSP on oxidative stress-induced neuronal toxicity using human neuroblastoma SH-SY5Y cells. Pretreatment with RNSP significantly ameliorated the hydrogen peroxide- (H2O2-) induced cytotoxicity of SH-SY5Y cells in a dose-dependent manner (up to 60 μg/mL). Furthermore, RNSP significantly reduced the H2O2-induced upregulation of 8-oxo-2'-deoxyguanosine (8-oxo-dG, the oxidative DNA damage marker) but significantly reversed the expression of repressor element-1 silencing transcription factor (REST) from H2O2 associated (100 μM) downregulation. Moreover, RNSP significantly attenuated the H2O2-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase 1/2 (ERK 1/2) in SH-SY5Y cells. These observations strongly suggest that RNSP may protect the oxidative stress-induced neuronal damage that occurs through the properties of various antioxidants and inhibit the activation of MAPKs. We thus provide the principle molecular mechanisms of the effects of RNSP and indicate its role in the prevention and clinical management of AD.

Green tea polyphenols protect spinal cord neurons against hydrogen peroxide-induced oxidative stress

Green tea polyphenols are strong antioxidants and can reduce free radical damage. To investigate their neuroprotective potential, we induced oxidative damage in spinal cord neurons using hydrogen peroxide, and applied different concentrations (50–200 μg/mL) of green tea polyphenol to the cell medium for 24 hours. Measurements of superoxide dismutase activity, malondialdehyde content, and expression of apoptosis-related genes and proteins revealed that green tea polyphenol effectively alleviated oxidative stress. Our results indicate that green tea polyphenols play a protective role in spinal cord neurons under oxidative stress.

Coptis chinensis Franch. exhibits neuroprotective properties against oxidative stress in human neuroblastoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

The dried rhizome of Coptis chinensis Franch. (family Ranunculaceae) is traditionally used in Chinese medicine for the treatment of inflammatory diseases and diabetes. Recent studies showed a variety of activities of Coptis chinensis Franch. alkaloids, including neuroprotective, neuroregenerative, anti-diabetic, anti-oxidative and anti-inflammatory effects. However, there is no report on the neuroprotective effect of Coptis chinensis Franch. watery extract against tert-butylhydroperoxide (t-BOOH) induced oxidative damage. The aim of the study is to investigate neuroprotective properties of Coptis chinensis Franch. rhizome watery extract (CRE) and to evaluate its potential mechanism of action.

MATERIALS AND METHODS

Neuroprotective properties on t-BOOH induced oxidative stress were investigated in SH-SY5Y human neuroblastoma cells. Cells were pretreated with CRE for 2 h or 24 h followed by 2 h of treatment with t-BOOH. To evaluate the neuroprotective effect of CRE, cell viability, cellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and the apoptotic rate were determined and microarray analyses, as well as qRT-PCR analyses were conducted.

RESULTS

Two hours of exposure to 100 µM t-BOOH resulted in a significant reduction of cell viability, increased apoptotic rate, declined mitochondrial membrane potential (MMP) and increased ROS production. Reduction of cell viability, increased apoptotic rate and declined mitochondrial membrane potential (MMP) could be significantly reduced in cells pretreated with CRE (100 µg/ml) for 2h or 24h ahead of t-BOOH exposure with the greatest effect after 24h of pretreatment; however ROS production was not changed significantly. Furthermore, microarray analyses revealed that the expressions of 2 genes; thioredoxin-interacting protein (TXNIP) and mitochondrially encoded NADH dehydrogenase 1, were significantly regulated. Down regulation of TXNIP was confirmed by qRT-PCR.

CONCLUSION

Due to its neuroprotective properties CRE might be a potential therapeutic agent for the prevention or amelioration of diseases like diabetic neuropathy and neurodegenerative disorders like Alzheimer and Parkinsons disease.

Neuroprotective effects of melittin on hydrogen peroxide-induced apoptotic cell death in neuroblastoma SH-SY5Y cells

Background

Free radicals are involved in neuronal cell death in human neurodegenerative diseases. Since ancient times, honeybee venom has been used in a complementary medicine to treat various diseases and neurologic disorders. Melittin, the main component of honeybee venom, has various biologic effects, including anti-bacterial, anti-viral, and anti-inflammatory activities.

Methods

We investigated the neuroprotective effects of melittin against H₂O₂-induced apoptosis in the human neuroblastoma cell line SH-SY5Y. The neuroprotective effects of melittin on H₂O₂-induced apoptosis were investigated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylterazolium bromide assay, caspase 3 activity, 4,6-diamidino-2-phenylindole staining, a lactate dehydrogenase release assay, Western blots, and reverse transcription-polymerase chain reaction.

Results

The H₂O₂-treated cells had decreased cell viability with apoptotic features and increased production of caspase-3. On the other hand, melittin treatment increased cell viability and decreased apoptotic DNA fragmentation. Melittin attenuated the H₂O₂-induced decrease in mRNA and protein production of the anti-apoptotic factor Bcl-2. In addition, melittin inhibited both the H₂O₂-induced mRNA and protein expression of Bax-associated pro-apoptotic factor and caspase-3.

Conclusions

These findings suggest that melittin has potential therapeutic effects as an agent for the prevention of neurodegenerative diseases.

Gui-ling-gao, a traditional Chinese functional food, prevents oxidative stress-induced apoptosis in H9c2 cardiomyocytes

Functional foods have become an increasingly popular alternative to prevent diseases and maintain body health status. Gui-ling-gao (GLG, also known as turtle jelly) is a well-known traditional functional food popular in Southern China and Hong Kong. This study aimed to investigate the antioxidative and anti-apoptotic effects of GLG, a traditional Chinese functional food, on preventing oxidative stress-induced injury in H9c2 cardiomyocytes. In this study, the antioxidative capacities of GLG were measured by using both a cell-free assay [2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl assay] and biological methods [2,2'-azobis(2-amidinopropane)-induced haemolysis assay and H(2)O(2)-induced cell damage on H9c2 cardiomyocytes]. Additionally, the total phenolic content was measured using the Folin-Ciocalteu method. Furthermore, the anti-apoptotic effect of GLG was evaluated by nuclear staining and a DNA fragmentation assay. GLG was found to have good antioxidant activities and high total phenolic content. In H(2)O(2)-induced cell damage on H9c2 cells, GLG was demonstrated to ameliorate the apoptotic effects, such as nuclear condensations, increased intracellular caspase-3 activity and inter-nucleosomal DNA cleavage, induced by H(2)O(2). The present study demonstrated for the first time that GLG possesses anti-apoptotic potential in vitro and this effect may be mediated, in part, by its antioxidative function. Additionally, the antioxidative capacities of GLG were proved both chemically and biologically. This study provides scientific evidence to prove the anecdotal health-beneficial claim that the consumption of GLG could help the body to handle endogenous toxicants such as free radicals.

TDAG51 deficiency promotes oxidative stress-induced apoptosis through the generation of reactive oxygen species in mouse embryonic fibroblasts

Apoptosis has an important role in maintaining tissue homeostasis in cellular stress responses such as inflammation, endoplasmic reticulum stress, and oxidative stress. T-cell death-associated gene 51 (TDAG51) is a member of the pleckstrin homology-like domain family and was first identified as a pro-apoptotic gene in T-cell receptor-mediated cell death. However, its pro-apoptotic function remains controversial. In this study, we investigated the role of TDAG51 in oxidative stress-induced apoptotic cell death in mouse embryonic fibroblasts (MEFs). TDAG51 expression was highly increased by oxidative stress responses. In response to oxidative stress, the production of intracellular reactive oxygen species was significantly enhanced in TDAG51-deficient MEFs, resulting in the activation of caspase-3. Thus, TDAG51 deficiency promotes apoptotic cell death in MEFs, and these results indicate that TDAG51 has a protective role in oxidative stress-induced cell death in MEFs.

C-terminal peptide of γ-enolase impairs amyloid-β-induced apoptosis through p75(NTR) signaling

γ-Enolase acts as a neurotrophic-like factor promoting growth, differentiation, survival and regeneration of neurons. It is shown in this study to exert a protective effect against amyloid-β-peptide (Aβ)-induced neurotoxicity in rat pheochromocytoma PC12 cells. Aβ-induced toxicity was abolished in the presence of the active C-terminal peptide of γ-enolase (γ-Eno) as measured by cell viability, lactate dehydrogenase release, sub-G1 cell population, intracellular reactive oxygen species, mitochondrial functions and apoptotic morphology. γ-Eno caused downregulation of the pro-apoptotic protein Bax and upregulation of the anti-apoptotic protein Bcl-2, as well as reduced caspase-3 activation. Exposure to Aβ increased surface expression of p75 neurotrophin receptor (p75(NTR)), and the increase was abolished in the presence of γ-Eno peptide. Further, pretreatment with γ-Eno suppressed the activation of mitogen-activated protein kinases p38 and Jun-N-terminal kinase, which are p75(NTR) downstream effectors in apoptotic signaling. Moreover, Aβ triggered γ-enolase co-immunoprecipitation with p75(NTR) as well as their strong association in the perimembrane region as shown by confocal microscopy, which further supports the interaction between these two proteins in cells insulted by Aβ peptide. Our results indicate the possible use of γ-enolase C-terminal peptide for treating or preventing Alzheimer's disease.

The possible role of the transcription factor nuclear factor-κB on evolution of rotator cuff tear and on mechanisms of cuff tendon healing

BACKGROUND

We verified if the nuclear factor-κB (NF-κB) was present on the margins of rotator cuff tears (RCTs). Because NF-κB regulates apoptosis and stimulates neoangiogenesis, we hypothesized that NF-κB has a role in the evolution of RCT and in possible mechanisms of RCT healing.

MATERIALS AND METHODS

Samples from tear margins, subacromial bursa, and healthy subscapular tendons were excised during arthroscopic treatment of patients with posterosuperior RCT. Sections were cut and stained with hematoxylin and eosin for morphologic evaluation and used for immunohistochemical analysis with NF-κB p65 antibody.

RESULTS

The presence of NF-κB in the RCT margins and subacromial bursa increases with increasing tear size. NF-κB is also present in the subscapularis tendon of patients with large and massive RCT. Analogously, we observed that neoangiogenesis grows with increasing RCT size and is always present in the subscapularis tendon independently from RCT size. Statistical analysis indicates that NF-κB and neoangiogenesis are correlated, regardless of the dimension of the RCT.

CONCLUSIONS

This is the first study that identifies the association between activated NF-κB and RCT. Activated NF-κB on the margins of RCT increases with increasing tear size. We hypothesized a series of possible causes responsible for NF-κB activation; however, we believe that activation is due to tissue hypoxia. Activated p65 directly stimulates neoangiogenesis, but the same factors that regulate NF-κB activation might also act as neoangiogenesis inductors.

Neuroprotective effects of luteolin against apoptosis induced by 6-hydroxydopamine on rat pheochromocytoma PC12 cells

CONTEXT

Apoptotic neuronal cell death plays an important role in Parkinson's disease (PD), a progressive neurodegenerative disorder. Luteolin, a flavonoid, has been shown to possess various pharmacological properties including strong antioxidant capacity.

OBJECTIVE

This study investigated the neuroprotective effect of luteolin against cytotoxicity induced by 6-hydroxy-dopamine (6-OHDA) (250 µM) in rat pheochromocytoma (PC12) cell line.

MATERIALS AND METHODS

The neuroprotective effect of luteolin against 6-OHDA-induced cytotoxicity in PC12 was evaluated by using cell viability test, nuclear staining and flow cytometry. In addition, the apoptotic role of luteolin was unveiled by monitoring mRNA expression of proapoptotic and anti-apoptotic genes.

RESULTS

Pretreatment with luteolin (3.13, 6.25, 12.5, 25 or 50 µM) could markedly attenuate 6-OHDA-induced PC12 cell viability loss in a concentration-dependent manner. Cell morphologic analysis and nuclear staining assays showed that luteolin (3.13, 12.5 or 50 µM) protected the cells from 6-OHDA-induced damage. As shown in the flow cytometry assay, the increased apoptotic rate induced by 6-OHDA could be significantly (p < 0.001) suppressed by luteolin (12.5 or 50 µM) pretreatment. The protection of luteolin (50 µM) against 6-OHDA-induced cell damage was shown to be through suppressing the over-expression of Bax gene (p < 0.01), inhibiting the reduction of Bcl-2 gene expression (p < 0.05) and markedly depressing the enhanced Bax/Bcl-2 ratio. Luteolin also downregulated the gene expression level of p53.

DISCUSSION AND CONCLUSION

Luteolin has protective effects against 6-OHDA-induced cell apoptosis and might be a potential nutritional supplement which could be used to prevent neurodegenerative diseases such as PD.

Edaravone protects HT22 neurons from H2O2-induced apoptosis by inhibiting the MAPK signaling pathway

AIMS

Oxidative stress is frequently implicated in the pathology of neurodegenerative diseases. This study aimed to investigate the effects and their underlying mechanism(s) of edaravone upon hydrogen peroxide (H2O2)-induced oxidative stress and apoptosis in HT22 cells, a murine hippocampal neuronal model.

METHODS

HT22 cells were treated with H2O2 in the presence of various concentrations of edaravone or in its absence. A CCK-8 assay, Hoechst 33342 staining, and flow cytometry were used to detect cytotoxicity and apoptosis. In addition, the levels of reactive oxygen species (ROS) and the expression of Bcl-2, Bax, p-ERK 1/2, p-JNK, and p-P38 proteins in HT22 cells were examined.

RESULTS

Exogenous H2O2 decreased cell viability in a concentration-dependent manner and was associated with increased apoptosis and ROS production. Moreover, H2O2 significantly activated and upregulated the expression of p-ERK 1/2, p-JNK, and p-P38, while edaravon protected HT22 cells against H2O2-induced injury by inhibiting the production of ROS and activating the MAPK signaling pathway.

CONCLUSIONS

Our results provide the first evidence that edaravone can protect H2O2-induced cell injury in HT22 neurons via its antioxidant action. These findings suggest that edaravone may be useful in the treatment of neurodegenerative disorders in which oxidative stress has been principally implicated.

The protective effect of astrocyte-derived 14,15-epoxyeicosatrienoic acid on hydrogen peroxide-induced cell injury in astrocyte-dopaminergic neuronal cell line co-culture

Astrocytes perform several functions that are essential for normal neuronal activity. They play a critical role in neuronal survival during ischemia and other degenerative injuries and also modulate neuronal recovery by influencing neurite outgrowth. In this study, we investigated the neuroprotective effects of astrocyte-derived 14,15-epoxyeicosatrienoic acid (14,15-EET), metabolite of arachidonic acid by cytochrome P450 epoxygenases (CYP), against oxidative stress induced by hydrogen peroxide (H(2)O(2)). We found that dopaminergic neuronal cells (N27 cell line) stimulated with two different doses of H(2)O(2) (0.1 and 1mM) for 1h showed decreased cell viability compared to the control group, while astrocytes showed less cell death after stimulation with the same doses of H(2)O(2) for 1h. Dopaminergic neuronal cells (N27 cell line) pretreated with different doses of 14,15-EET (0.1-30 μM, 30 min) before H(2)O(2) stimulation also showed increased cell viability. Furthermore, pre-treatment of the co-cultured cells with 12-(3-adamantan-1-yl-ureido)-dodecanoic acid, an inhibitor of the EET metabolizing enzyme, soluble epoxide hydrolase (sEH), before H(2)O(2) stimulation (1mM, for 1h) increased cell viability. It also increased the endogenous level of 14,15-EET in the media compared to control group. However, pretreatment with the CYP epoxygenase inhibitor miconazole (1-20 μM, 1h) before H(2)O(2) (1mM, 1h) stimulation showed decreased cell viability. Our data suggest that 14,15-EET which is released from astrocytes, enhances cell viability against oxidant-induced injury. Further understanding of the mechanism of 14,15-EET-mediated protection in dopaminergic neurons is imperative, as it could lead to novel therapeutic approaches for treating CNS neuropathologies, such as Parkinson's disease.

Reactive oxygen/nitrogen species and their functional correlations in neurodegenerative diseases

The continuous production and efflux of reactive oxygen/nitrogen species from endogenous and exogenous sources can damage biological molecules and initiate a cascade of events. Mitochondria are pivotal in controlling cell survival and death. Cumulative oxidative stress, disrupted mitochondrial respiration, and mitochondrial damage are related with various neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and others. Biochemical cascades of apoptosis are mediated in signaling molecules, including protein kinases and transcription factors. The expressions in the pro-apoptotic signal transduction networks may indeed promote cell death and degeneration in brain cells. The regulation of that protein phosphorylation by kinases and phosphatases is emerging as a prerequisite mechanism in the control of the apoptotic cell death program. In this review, we attempt to put forth the evidence for possible mechanistic explanations for involvement of free radicals in the pathogenesis of neurodegenerative diseases.

Icariin inhibits hydrogen peroxide-induced toxicity through inhibition of phosphorylation of JNK/p38 MAPK and p53 activity

Oxidative stress caused by hydrogen peroxide (H(2)O(2)) plays an important role in the pathogenesis of Alzheimer's disease (AD). The prominent damages caused by H(2)O(2) include the ruin of membrane integrity, loss of intracellular neuronal glutathione (GSH), oxidative damage to DNA as well as the subsequent caspase-3 and p53 activation. Icariin is a flavonoid extracted from the traditional Chinese herb Epimedium brevicornum Maxim. We have previously reported that icariin has a good curative effect on patients with mild cognitive impairment (MCI), AD animal and cell models. However, the molecular mechanism of how icariin exerts neuroprotective effects is still not well understood. To address this question, we exposed undifferentiated neuronal cell lines (PC12 cells) to hydrogen peroxide (H(2)O(2)) and investigated the possible neuroprotective mechanisms of icariin. Vitamin E was used as a positive control. We observed that H(2)O(2) activated the JNK/p38 mitogen-activated protein kinase (MAPK) and induced PC12 cells apoptosis in a concentration-dependent manner. More over, we demonstrated that icariin protected PC12 cells by attenuating LDH leakage, reducing GSH depletion, preventing DNA oxidation damage and inhibiting subsequent activation of caspase-3 and p53, which are the main targets of H(2)O(2)-induced cell damage. In addition, we also found that icariin's neuroprotective effect may partly correlate with its inhibitory effect on JNK/p38 MAPK pathways. Therefore, our findings suggest that icariin is a candidate for a novel neuroprotective drug to against oxidative-stress induced neurodegeneration.