Bcl-2 facilitates recovery from DNA damage after oxidative stress

PGD2 displays distinct effects in diffuse large B-cell lymphoma depending on different concentrations

Prostaglandin D2 (PGD2), an arachidonic acid metabolite, has been implicated in allergic responses, parasitic infection and tumor development. The biological functions and molecular mechanisms of PGD2 in diffuse large B-cell lymphoma (DLBCL) are still undefined. In this study, we firstly found the high concentration of serum PGD2 and low expression of PGD2 receptor CRTH2 in DLBCL, which were associated with clinical features and prognosis of DLBCL patients. Interestingly, different concentration of PGD2 displayed divergent effects on DLBCL progression. Low-concentration PGD2 promoted cell growth through binding to CRTH2 while high-concentration PGD2 inhibited it via regulating cell proliferation, apoptosis, cell cycle, and invasion. Besides, high-concentration PGD2 could induce ROS-mediated DNA damage and enhance the cytotoxicity of adriamycin, bendamustine and venetoclax. Furthermore, HDAC inhibitors, vorinostat (SAHA) and panobinostat (LBH589) regulated CRTH2 expression and PGD2 production, and CRTH2 inhibitor AZD1981 and high-concentration PGD2 enhanced their anti-tumor effects in DLBCL. Altogether, our findings demonstrated PGD2 and CRTH2 as novel prognostic biomarkers and therapeutic targets in DLBCL, and highlighted the potency of high-concentration PGD2 as a promising therapeutic strategy for DLBCL patients.

The Behavioral and Neurochemical Changes Induced by Boldenone and/or Tramadol in Adult Male Rats

Boldenone and tramadol are abused among large sectors of adolescents. Therefore, the behavioral changes concerned with memory and cognitive functions and neurochemical variations were investigated in the cortex of rats treated with boldenone and/or tramadol. Rats were divided into control and rats treated with boldenone, tramadol, or both drugs. At the end of the treatment period, the memory and cognitive functions were evaluated by the Y-maze test (YMT) and elevated plus maze test (EPMT) and the motor activity was determined by the open field test (OFT). The cortex was dissected to carry out the neurochemical analyses. Rats treated with boldenone and/or tramadol showed impaired memory and cognitive functions and reduced motor activity. A significant increase in lipid peroxidation (MDA), nitric oxide (NO), and a significant decrease in reduced glutathione (GSH) were observed in the cortex of rats treated with boldenone and/or tramadol. The levels of acetylcholinesterase (AChE) and monoamine oxidase (MAO) decreased significantly. Western blot data showed a significant decrease in Bcl2 and a significant increase in caspase-3 and inducible nitric oxide synthase (iNOS) in rats treated with boldenone and/or tramadol. These changes were associated with neuronal death as indicated from the histopathological examination.

The present findings indicate that boldenone and/or tramadol induced impairment in memory and cognitive functions. These changes could be mediated by the increase in oxidative stress, neuroinflammation, reduced AChE level, and reduced number of survived neurons in the cortex as indicated from the decreased Bcl2 level and the histological examination.

Membrane-Free Stem Cells and Pyridoxal 5'-Phosphate Synergistically Enhance Cognitive Function in Alzheimer's Disease Mouse Model

Accumulation of amyloid beta (Aβ) is a major pathological hallmark of Alzheimer’s disease (AD). In this study, we evaluated the protective effect of membrane-free stem cell extract (MFSCE), which is a component of adipose-tissue-derived stem cells, on cognitive impairment in Aβ_25–35-injected AD mice. The ICR mice were i.c.v. injected with Aβ_25–35 and then treated with MFSCE for 14 days (i.p.). The Aβ_25–35-injected mice showed deficits in spatial and object perception abilities, whereas treatment with MFSCE inhibited Aβ_25–35-induced learning and memory impairment in the T-maze, novel object recognition, and Morris water maze tests. Moreover, Aβ_25–35-induced lipid peroxidation and nitric oxide overproduction were attenuated by treatment with MFSCE. These antioxidant effects of MFSCE were related to the inhibition of the apoptotic signaling pathway. In particular, the combination treatment of MFSCE and pyridoxal 5′-phosphate (PLP) showed greater suppression of Bax and cleaved caspase-3 protein expression compared to the MFSCE- or PLP-only treatment. Furthermore, the MFSCE and PLP combination significantly downregulated the amyloidogenic-pathway-related protein expressions, such as amyloid precursor protein, presenilin 1, and presenilin 2. Therefore, the MFSCE and PLP combination may synergistically prevent Aβ_25–35-induced neuronal apoptosis and amyloidogenesis, which contributes to cognitive improvement and has potential therapeutic implications for AD patients.

LRP::FLAG Reduces Phosphorylated Tau Levels in Alzheimer's Disease Cell Culture Models

BACKGROUND

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) plaque and neurofibrillary tangle formation, respectively. Neurofibrillary tangles form as a result of the intracellular accumulation of hyperphosphorylated tau. Telomerase activity and levels of the human reverse transcriptase (hTERT) subunit of telomerase are significantly decreased in AD. Recently, it has been demonstrated that the 37 kDa/67 kDa laminin receptor (LRP/LR) interacts with telomerase and is implicated in Aβ pathology. Since both LRP/LR and telomerase are known to play a role in the Aβ facet of AD, we hypothesized that they might also play a role in tauopathy.

OBJECTIVE

This study aimed to determine if LRP/LR has a relationship with tau and whether overexpression of LRP::FLAG has an effect on tauopathy-related proteins.

METHODS

We employed confocal microscopy and FRET to determine whether LRP/LR and tau co-localize and interact. LRP::FLAG overexpression in HEK-293 and SH-SY5Y cells as well as analysis of tauopathy-related proteins was assessed by western blotting.

RESULTS

We demonstrate that LRP/LR co-localizes with tau in the perinuclear cell compartment and confirmed a direct interaction between LRP/LR and tau in HEK-293 cells. Overexpression of LRP::FLAG in HEK-293 and SH-SY5Y cells decreased total and phosphorylated tau levels with a concomitant decrease in PrPc levels, a tauopathy-related protein. LRP::FLAG overexpression also resulted in increased hTERT levels.

CONCLUSION

This data suggest that LRP/LR extends its role in AD through a direct interaction with tau, and recommend LRP::FLAG as a possible alternative AD therapeutic via decreasing phosphorylated tau levels.

The role of Bcl-2 proteins in modulating neuronal Ca2+ signaling in health and in Alzheimer's disease

The family of B-cell lymphoma-2 (Bcl-2) proteins exerts key functions in cellular health. Bcl-2 primarily acts in mitochondria where it controls the initiation of apoptosis. However, during the last decades, it has become clear that this family of proteins is also involved in controlling intracellular Ca2+ signaling, a critical process for the function of most cell types, including neurons. Several anti- and pro-apoptotic Bcl-2 family members are expressed in neurons and impact neuronal function. Importantly, expression levels of neuronal Bcl-2 proteins are affected by age. In this review, we focus on the emerging roles of Bcl-2 proteins in neuronal cells. Specifically, we discuss how their dysregulation contributes to the onset, development, and progression of neurodegeneration in the context of Alzheimer's disease (AD). Aberrant Ca2+ signaling plays an important role in the pathogenesis of AD, and we propose that dysregulation of the Bcl-2-Ca2+ signaling axis may contribute to the progression of AD and that herein, Bcl-2 may constitute a potential therapeutic target for the treatment of AD.

Morroniside protects OLN-93 cells against H2O2-induced injury through the PI3K/Akt pathway-mediated antioxidative stress and antiapoptotic activities

Neurodegenerative disorders, including spinal cord injury (SCI), result in oxidative stress-induced cell damage. Morroniside (MR), a major active ingredient of the Chinese herb Shan Zhu Yu, has been shown to ameliorate oxidative stress and inflammatory response. Our previous study also confirmed that morroniside protects SK-N-SH cell line (human neuroblastoma cells) against oxidative impairment. However, it remains unclear whether MR also plays a protective role for oligodendrocytes that are damaged following SCI. The present study investigated the protective effects of MR against hydrogen peroxide (H₂O₂)-induced cell death in OLN-93 cells. MR protected OLN-93 cells from H₂O₂-induced injury, attenuated H₂O₂-induced increase in reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and blocked the reduction of mitochondrial membrane potential (MMP) induced by H2O2. MR enhanced the activity of the antioxidant enzyme superoxide dismutase (SOD) and suppressed H₂O₂-induced downregulation of the antiapoptotic protein Bcl-2 and activation of the proapoptotic protein caspase-3. Finally, we found that LY294002, a specific inhibitor of the PI3K/Akt pathway, inhibited the protective effect of MR against H₂O₂-induced OLN-93 cell injury in the MTT and TUNEL assays. LY294002 also inhibited the expression of SOD and Bcl-2, and increased the expression of iNOS and c-caspase-3 induced by MR treatment. MR exerts protective effects against H₂O₂-induced OLN-93 cell injury through the PI3K/Akt signaling pathway-mediated antioxidative stress and antiapoptotic activities. MR may provide a potential strategy for SCI treatment or other related neurodegeneration.

Artemisinin Improved Neuronal Functions in Alzheimer's Disease Animal Model 3xtg Mice and Neuronal Cells via Stimulating the ERK/CREB Signaling Pathway

The most common form of dementia is Alzheimer’s disease which is characterized by memory loss and cognitive disorders. The pathogenesis of Alzheimer’s disease is not known at present but toxicity of amyloid-beta is one of the central hypotheses. Amyloid-beta can stimulate the production of reactive oxygen species (ROS), cause oxidative stress, damage mitochondrial, cause inflammatory reactions and activate apoptosis related factors which lead to the neuronal death. In this study, we found that artemisinin, a first line antimalarial drug used in clinic for decades, improved the cognitive functions in Alzheimer’s disease animal model 3xTg mice. Further study showed that artemisinin reduced the deposition of amyloid-beta and tau protein, reduced the release of inflammation factors and apoptosis factors, and thereby reduced the neuronal cell death. Western blot assay showed that artemisinin stimulated the activation of ERK/CREB signaling pathway. Consistent with these results, artemisinin concentration-dependently promoted the survival of SH-SY5Y cell against toxicity of amyloid-beta protein 1-42 induced ROS accumulation, caspase activation and apoptosis. Artemisinin also stimulated the phosphorylation of ERK1/2 and CREB in SH-SY5Y cells in time and concentration-dependent manner. Inhibition of ERK/CREB pathway attenuated the protective effect of artemisinin. These data put together suggested that artemisinin has the potential to protect neuronal cells in vitro as well as in vivo animal model 3xTg mice via, at least in part, the activation of the ERK/CREB pathway. Our findings also strongly support the potential of artemisinin as a new multi-target drug that can be used for preventing and treating the Alzheimer’s disease.

Liposomal encapsulation of silver nanoparticles (AgNP) improved nanoparticle uptake and induced redox imbalance to activate caspase-dependent apoptosis

Macrophages play a crucial role in several diseases' development and progression, such as in cancer and arthritis through ROS generation and inflammation. This makes macrophages a therapeutic target in these diseases. While silver nanoparticles (AgNP) have been widely used as an antibacterial and investigated as anticancer, its potential against macrophages may be limited due to its inherent oxidative mechanism. Here we encapsulated AgNP in a dipalmitoyl-phosphatidyl choline (DPPC) liposome (forming Lipo-AgNP) to suppress AgNP-induced ROS and enhance its cytotoxicity against THP1-differentiated macrophages (TDM). Our findings showed that while Lipo-AgNP had significantly more of a cytotoxic effect on TDMs (p < 0.01), it also significantly suppressed AgNP induced ROS generation and unexpectedly suppressed reduced glutathione (GSH) levels (p < 0.05) resulting in a redox imbalance in comparison to the unexposed control TDMs. Lipo-AgNP was also found to cause an increase DNA damage through H2AX histone phosphorylation and inhibition of Bcl-2 protein expression. This increased the Bax/Bcl2 ratio causing possible release of cytochrome C and subsequent caspase 3/7-dependent apoptosis. It was found that the difference between the mechanism of AgNP and Lipo-AgNP cytotoxicity may have been through the significantly increased Lipo-AgNP uptake by the TDMs as early as 30 min post-exposure (p < 0.05), changing the nanoparticle pharmacokinetic. In conclusion, the improved uptake of AgNP within the liposome caused ROS-independent caspase activation induced by Lipo-AgNP and this was facilitated by increased DNA damage, the induced redox imbalance and an increased Bax/Bcl-2 ratio.

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.

LRP/LR specific antibody IgG1-iS18 impedes neurodegeneration in Alzheimer's disease mice

Alzheimer’s disease (AD) is a neurodegenerative disease caused by accumulation of amyloid beta (Aβ) plaque and neurofibrillary tangle formation. We have shown in vitro, that knock-down and blockade of the 37 kDa/67 kDa Laminin Receptor (LRP/LR) resulted in reduced Aβ induced cytotoxicity and Aβ accumulation. In order to test the effect of blocking LRP/LR on Aβ formation and AD associated symptoms, AD transgenic mice received the anti-LRP/LR specific antibody, IgG1-iS18 through intranasal administration. We show that this treatment resulted in an improvement in memory, and decreased Aβ plaque formation. Moreover, a significant decrease in Aβ₄₂ protein expression with a concomitant increase in amyloid precursor protein (APP) and telomerase reverse transcriptase (mTERT) levels was observed. These data recommend IgG1-iS18 as a potentially powerful therapeutic antibody for AD treatment.

Cross-linking by epichlorohydrin and diepoxybutane correlates with cytotoxicity and leads to apoptosis in human leukemia (HL-60) cells

The bifunctional alkylating agents epichlorohydrin (ECH) and diepoxybutane (DEB) have been linked to increased cancer risks in industrial workers. These compounds react with DNA and proteins, leading to genotoxic effects. We used the comet assay to monitor formation of cross-links in HL-60 cells treated with ECH, DEB, and the structurally related anti-cancer drug mechlorethamine (HN2). We report a time- and dose-dependent cytotoxicity that correlated with cross-linking activity, following the order HN2 > DEB > ECH. The rate of cross-link repair also varied with drug, with ECH-induced lesions the fastest to repair. High drug doses led to the formation of saturating amounts of HN2 cross-links that were repaired inefficiently. DEB and ECH produced fewer overall cross-links, but some were also resistant to repair. These persistent cross-links may activate cell-cycle arrest to allow repair of damage, with prolonged arrest triggering apoptosis. Quantitative reverse transcription polymerase chain reaction experiments revealed that treatment of HL-60 cells with DEB and ECH results in up-regulation of several genes involved in the intrinsic (mitochondrial) apoptosis pathway, including BAX, BAK1, CASP-9, APAF-1, and BCL-2. These findings contribute to our understanding of the principles underlying the carcinogenic potentials of these xenobiotics.

Bcl-2 protects TK6 cells against hydroquinone-induced apoptosis through PARP-1 cytoplasm translocation and stabilizing mitochondrial membrane potential

B cell leukemia/lymphoma-2 (Bcl-2) suppresses apoptosis by binding the BH3 domain of proapoptotic factors and thereby regulating mitochondrial membrane potential (MMP). This study aimed to investigate the role of Bcl-2 in controlling the mitochondrial pathway of apoptosis during hydroquinone (HQ)-induced TK6 cytotoxicity. In this study, HQ, one metabolite of benzene, decreased the MMP in a concentration-dependent manner and induced the generation of reactive oxygen species (ROS), the activation of the DNA damage marker γ-H2AX, and production of the DNA damage-responsive enzyme poly(ADP-ribose)polymerase-1 (PARP-1). Exposure of TK6 cells to HQ leads to an increase in Bcl-2 and co-localization with PARP-1 in the cytoplasm. Inhibition of Bcl-2 using the BH3 mimetic, ABT-737, suppressed the PARP-1 nuclear to cytoplasm translocation and sensitized TK6 cells to HQ-induced apoptosis through depolarization of the MMP. Western blot analysis indicated that ABT-737 combined with HQ increased the levels of cleaved PARP and γ-H2AX, but significantly decreased the level of P53. Thus, ABT-737 can influence PARP-1 translocation and induce apoptosis via mitochondria-mediated apoptotic pathway, independently of P53. In addition, we found that knockdown of PARP-1 attenuated the HQ-induced production of cleaved PARP and P53. These results identify Bcl-2 as a protective mediator of HQ-induced apoptosis and show that upregulation of Bcl-2 helps to localize PARP-1 to the cytoplasm and stabilize MMP. Environ. Mol. Mutagen. 59:49-59, 2018. © 2017 Wiley Periodicals, Inc.

Morroniside protects SK-N-SH human neuroblastoma cells against H2O2-induced damage

Oxidative stress-induced cell injury has been linked to the pathogenesis of neurodegenerative disorders such as spinal cord injury, Parkinson's disease, and multiple sclerosis. Morroniside is an antioxidant derived from the Chinese herb Shan-Zhu-Yu. The present study investigated the neuroprotective effect of morroniside against hydrogen peroxide (H₂O₂)-induced cell death in SK-N-SH human neuroblastoma cells. H₂O₂ increased cell apoptosis, as determined by flow cytometry and Hoechst 33342 staining. This effect was reversed by pretreatment with morroniside at concentrations of 1–100 µM. The increase in intracellular reactive oxygen species (ROS) generation and lipid peroxidation induced by H₂O₂ was also abrogated by morroniside. H₂O₂ induced a reduction in mitochondrial membrane potential, increased caspase-3 activity, and caused downregulation of B cell lymphoma-2 (Bcl-2) and upregulation of Bcl-2-associated X protein (Bax) expression. These effects were blocked by morroniside pretreatment. Thus, morroniside protects human neuroblastoma cells against oxidative damage by inhibiting ROS production while suppressing Bax and stimulating Bcl-2 expression, thereby blocking mitochondrial-mediated apoptosis. These results indicate that morroniside has therapeutic potential for the prevention and treatment of neurodegenerative diseases.

Biocompatible Azide-Alkyne "Click" Reactions for Surface Decoration of Glyco-Engineered Cells

Bio-orthogonal copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been widely used to modify azide- or alkyne-bearing monosaccharides on metabolic glyco-engineered mammalian cells. Here, we present a systematic study to elucidate the design space for the cytotoxic effects of the copper catalyst on NIH 3T3 fibroblasts and on HEK 293-F cells. Monitoring membrane integrity by flow cytometry and RT-PCR analysis with apoptotic and anti-apoptotic markers elucidated the general feasibility of CuAAC, with exposure time of the CuAAC reaction mixture having the major influence on biocompatibility. A high labeling efficiency of HEK 293-F cells with a fluorescent alkyne dye was rapidly achieved by CuAAC in comparison to copper free strain-promoted azide-alkyne cycloaddition (SPAAC). The study details effective and biocompatible conditions for CuAAC-based modification of glyco-engineered cells in comparison to its copper free alternative.

Neuroprotective and neurorestorative potential of propargylamine derivatives in ageing: focus on mitochondrial targets

The mitochondrial theory of ageing proposes that accumulation of damage to mitochondrial function and DNA mutation lead to ageing of humans and animals. It has been suggested that mitochondria play dynamic roles in regulating synaptogenesis and morphological/functional responses of synaptic activity, and thus, deteriorating of mitochondrial function (e.g., deficits of the mitochondrial respiratory enzymes, reduced calcium influx, increased accumulation of mitochondrial DNA defects/apoptotic proteins and impairment of mitochondrial membrane potential) can lead to severe neuronal energy deficit, and in the long run, to modifications in neuronal synapses and neurodegeneration in the ageing brain. Hence, considering the mechanisms by which mitochondrial impairment can lead to neuronal death, the development of neuroprotective molecules that target various mitochondrial pathogenic processes can be effective in the treatment of ageing and age-related neurodegenerative diseases. This review addresses several aspects of the neuroprotective effects of propargylamine derivatives (e.g., the monoamine oxidase-B inhibitors, selegiline and rasagiline and the multifunctional drugs, ladostigil, M30 and VAR10303) in ageing with a special focus on mitochondrial molecular protective mechanisms.

Quantitative PCR-based measurement of nuclear and mitochondrial DNA damage and repair in mammalian cells

In this chapter, we describe a gene-specific quantitative PCR (QPCR)-based assay for the measurement of DNA damage, using amplification of long DNA targets. This assay has been used extensively to measure the integrity of both nuclear and mitochondrial genomes exposed to different genotoxins and has proven to be particularly valuable in identifying reactive oxygen species-mediated mitochondrial DNA damage. QPCR can be used to quantify both the formation of DNA damage as well as the kinetics of damage removal. One of the main strengths of the assay is that it permits monitoring the integrity of mtDNA directly from total cellular DNA without the need for isolating mitochondria or a separate step of mitochondrial DNA purification. Here we discuss advantages and limitations of using QPCR to assay DNA damage in mammalian cells. In addition, we give a detailed protocol of the QPCR assay that helps facilitate its successful deployment in any molecular biology laboratory.

Anti-apoptotic BCL-2 family proteins in acute neural injury

Cells under stress activate cell survival and cell death signaling pathways. Cell death signaling frequently converges on mitochondria, a process that is controlled by the activities of pro- and anti-apoptotic B-cell lymphoma 2 (BCL-2) proteins. In this review, we summarize current knowledge on the control of neuronal survival, development and injury by anti-apoptotic BCL-2 family proteins. We discuss overlapping and differential effects of the individual family members BCL-2, BCL-extra long (BCL-X_L), myeloid cell leukemia 1 (MCL-1), and BCL2-like 2 (BCL-W) in the control of survival during development and pathophysiological processes such as trophic factor withdrawal, ischemic injury, excitotoxicity, oxidative stress and energy stress. Finally we discuss recent evidence that several anti-apoptotic BCL-2 proteins influence mitochondrial bioenergetics and control neuronal Ca²⁺ homeostasis independent of their classical role in cell death signaling.

Cholesterol-enriched diet causes age-related macular degeneration-like pathology in rabbit retina

BACKGROUND

Alzheimer's disease (AD) and age-related macular degeneration (AMD) share several pathological hallmarks including β-amyloid (Aβ) accumulation, oxidative stress, and apoptotic cell death. The causes of AD and AMD are likely multi-factorial with several factors such as diet, environment, and genetic susceptibility participating in the pathogenesis of these diseases. Epidemiological studies correlated high plasma cholesterol levels with high incidence of AD, and feeding rabbits with a diet rich in cholesterol has been shown to induce AD-like pathology in rabbit brain. High intake of cholesterol and saturated fat were also long been suspected to increase the risk for AMD. However, the extent to which cholesterol-enriched diet may also cause AMD-like features in rabbit retinas is not well known.

METHODS

Male New Zealand white rabbits were fed normal chow or a 2% cholesterol-enriched diet for 12 weeks. At necropsy, animals were perfused with Dulbecco's phosphate-buffered saline and the eyes were promptly removed. One eye of each animal was used for immunohistochemistry and retina dissected from the other eye was used for Western blot, ELISA assays, spectrophotometry and mass spectrometry analyses.

RESULTS

Increased levels of Aβ, decreased levels of the anti-apoptotic protein Bcl-2, increased levels of the pro-apoptotic Bax and gadd153 proteins, emergence of TUNEL-positive cells, and increased generation of reactive oxygen species were found in retinas from cholesterol-fed compared to normal chow-fed rabbits. Additionally, astrogliosis, drusen-like debris and cholesterol accumulations in retinas from cholesterol-fed rabbits were observed. As several lines of evidence suggest that oxidized cholesterol metabolites (oxysterols) may be the link by which cholesterol contributes to the pathogenesis of AMD, we determined levels of oxysterols and found a dramatic increase in levels of oxysterols in retinas from cholesterol-fed rabbits.

CONCLUSIONS

Our results suggest that cholesterol-enriched diets cause retinal degeneration that is relevant to AMD. Furthermore, our data suggests high cholesterol levels and subsequent increase in the cholesterol metabolites as potential culprits to AMD.

DNA damage and impairment of DNA repair in Alzheimer's disease

Deoxyribonucleic acid (DNA) damage has been implicated in ageing and neurodegenerative disorders including Alzheimer's disease (AD) for a few decades. Although it is an established finding, yet there are limited studies on DNA damage. In both nucleus and mitochondria, DNA damage is primarily free radical mediated. It has been proven that mitochondrial DNA is more vulnerable to damage compared to the nuclear DNA. A few studies summarized in this review throw light on the mechanisms of free radical mediated DNA damage and impairment of DNA repair mechanisms in AD. There is a growing need to initiate studies on DNA damage and repair and unravel the molecular underpinnings entailed in the etiopathogenesis of the disease. The outcome of such studies substantiates the corner stone streamlined to employ therapeutic strategies.

Chapter 8: Clusterin: A multifacet protein at the crossroad of inflammation and autoimmunity

For years, clusterin has been recognized as a secreted protein and a large number of works demonstrated that this ubiquitously expressed protein has multiple activities. Among the described activities several were related to inflammation and immunity such as its regulatory activity on complement. Then it became clear that a nuclear form of the protein with proapoptotic property existed and more recently that a cytoplasmic form could regulate NF-kappaB pathway. Again, these activities have a strong repercussion in inflammation and immunity. On the other hand, data available on the exact role of CLU in these processes and autoimmunity were quite scarce until recently. Indeed, in the last few years, a differential CLU expression in subtype of T cells, the regulation of CLU expression by proinflammatory cytokines and molecules, the regulation of expression and function of CLU depending on its subcellular localization, the interaction of CLU with nuclear and intracellular proteins were all reported. Adding these new roles of CLU to the already reported functions of this protein allows a better understanding of its role and potential involvement in several inflammatory and immunological processes and, in particular, autoimmunity. In this sense, rheumatoid arthritis appears to be a very attractive disease to build a new paradigm of the role and function of CLU because it makes the link between proliferation, inflammation, and autoimmunity. We will try to see in this review how to bring altogether the old and new knowledge on CLU with inflammation and autoimmunity. Nevertheless, it is clear that CLU has not yet revealed all its secrets in inflammation and autoimmunity.

Effect of docosahexaenoic acid and eicosapentaenoic acid supplementation on oxidative stress levels during pregnancy

Docosahexaenoic acid (DHA) is an indispensable component of cell membranes with high requirements during pregnancy. DHA supplementation is thought to enhance oxidative stress because of increased likelihood of lipid peroxidation. We estimated the oxidative stress levels in two groups of pregnant women who received daily supply of required vitamins with (n = 23) or without (n = 23) 500 mg of DHA and 150 mg of eicosapentaenoic acid (EPA) from 20 weeks of gestation to the time of delivery. Urinary excretions of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage and of malondialdehyde (MDA), a marker of lipid peroxidation, were measured at 20, 30 weeks and at the time of delivery. Urinary MDA excretion remained unchanged throughout the study period in both groups. Urinary 8-OHdG excretion at delivery was significantly higher than at 20 and 30 weeks (p < 0.05), but there were no group differences at the three time points. There were no differences between the two groups in plasma a-tocopherol levels. We conclude that under the conditions studied, a daily supplementation of 500 mg DHA and 150 mg EPA with vitamins to pregnant women did not enhance lipid peroxidation or oxidative DNA damage.

Cytoprotective effects of a blue light-filtering intraocular lens on human retinal pigment epithelium by reducing phototoxic effects on vascular endothelial growth factor-alpha, Bax, and Bcl-2 expression

PURPOSE

To compare the possible protective effects of the ultraviolet (UV)-filtering and blue light-filtering SN60AT intraocular lens (IOL) and the untinted UV-filtering SA60AT IOL with regard to light-induced stress on human retinal pigment epithelium (RPE).

SETTING

Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany.

METHODS

Primary human RPE cells were exposed to white light, and a tinted or untinted IOL was placed in the light beam. After 15 to 60 minutes of irradiation, cell viability was determined by a colorimetric test (tetrazolium dye-reduction assay) and a microscopic live/dead assay. The expression of vascular endothelial growth factor-alpha (VEGF-alpha), Bax, and Bcl-2 and their mRNA was determined by reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting.

RESULTS

Without an IOL, white-light exposure decreased cell viability compared with the decrease with the nonirradiated control in a time-dependent manner. Light-induced cell death was significantly reduced by both the tinted IOL and untinted IOL. The combined UV and blue-light filtering attenuated light-induced cell damage significantly more than UV filtering alone. Results of RT-PCR and Western blotting showed a significant time-dependent decrease in Bcl-2 and increase in Bax and VEGF-alpha that were significantly less with the tinted IOL than with the untinted IOL.

CONCLUSIONS

Both IOLs reduced light-induced RPE damage. The UV- and blue light-filtering IOL reduced damage more than the conventional IOL. This supports the hypothesis that blue light-filtering IOLs may prevent retinal damage in clinical use.

Enhanced hypoxia susceptibility in hippocampal slices from a mouse model of rett syndrome

Rett syndrome is a neurodevelopmental disorder caused by mutations in the X-chromosomal MECP2 gene encoding for the transcriptional regulator methyl CpG binding protein 2 (MeCP2). Rett patients suffer from episodic respiratory irregularities and reduced arterial oxygen levels. To elucidate whether such intermittent hypoxic episodes induce adaptation/preconditioning of the hypoxia-vulnerable hippocampal network, we analyzed its responses to severe hypoxia in adult Rett mice. The occurrence of hypoxia-induced spreading depression (HSD)--an experimental model for ischemic stroke--was hastened in Mecp2-/y males. The extracellular K+ rise during HSD was attenuated in Mecp2-/y males and the input resistance of CA1 pyramidal neurons decreased less before HSD onset. CA1 pyramidal neurons were smaller and more densely packed, but the cell swelling during HSD was unaffected. The intrinsic optical signal and the propagation of HSD were similar among the different genotypes. Basal synaptic function was intact, but Mecp2-/y males showed reduced paired-pulse facilitation and higher field potential/fiber volley ratios, but no increased seizure susceptibility. Synaptic failure during hypoxia was complete in all genotypes and the final degree of posthypoxic synaptic recovery indistinguishable. Cellular ATP content was normal in Mecp2-/y males, but their hematocrit was increased as was HIF-1alpha expression throughout the brain. This is the first study showing that in Rett syndrome, the susceptibility of telencephalic neuronal networks to hypoxia is increased; the underlying molecular mechanisms apparently involve disturbed K+ channel function. Such an increase in hypoxia susceptibility may potentially contribute to the vulnerability of male Rett patients who are either not viable or severely disabled.

Mitochondrial DNA damage and repair in neurodegenerative disorders

By producing ATP and regulating intracellular calcium levels, mitochondria are vital for the function and survival of neurons. Oxidative stress and damage to mitochondrial DNA during the aging process can impair mitochondrial energy metabolism and ion homeostasis in neurons, thereby rendering them vulnerable to degeneration. Mitochondrial abnormalities have been documented in all of the major neurodegenerative disorders-Alzheimer's, Parkinson's and Huntington's diseases, and amyotrophic lateral sclerosis. Mitochondrial DNA damage and dysfunction may be downstream of primary disease processes such as accumulation of pathogenic proteins. However, recent experimental evidence demonstrates that mitochondrial DNA damage responses play important roles in aging and in the pathogenesis of neurodegenerative diseases. Therapeutic interventions that target mitochondrial regulatory systems have been shown effective in cell culture and animal models, but their efficacy in humans remains to be established.

Effects of banana, orange, and apple on oxidative stress-induced neurotoxicity in PC12 cells

Banana, orange, and apple are the major fruits in Western and Asian diets. In order to find the effects of these fruits, neuron like PC12 cells were exposed to the extracts of these fruits before H(2)O(2) treatment. We found a significant viability of PC12 cells by the MTT reduction test, which indicated that the phenolics of banana, orange, and apple fruits prevented oxidative stress-induced neurotoxicity. Additional tests by lactate dehydrogenase and trypan blue exclusion assays showed that the extracts reduced oxidative stress-induced neuronal cell membrane damage. These results suggest that fresh apples, banana, and orange in our daily diet along with other fruits may protect neuron cells against oxidative stress-induced neurotoxicity and may play an important role in reducing the risk of neurodegenerative disorders such as Alzheimer's disease.

Effect of quercetin on oxidative nuclear and mitochondrial DNA damage

Quercetin is a well-investigated antioxidant known to protect cells against oxidative nuclear DNA damage. There is no knowledge regarding its effect on oxidative mitochondrial DNA damage. In this study we investigated the effect of quercetin on oxidatively-injured DNA. Cell-free and cell studies were performed. Cell-free analyses carried out on plasmidic DNA showed that quercetin protects from all oxidative challenges used. Cellular studies were carried out on NCTC 2544 cells which were insulted with hydrogen peroxide and UVC radiations. Nuclear and mitochondrial DNAs were analysed by measuring DNA damage with a quantitative polymerase chain reaction. Quercetin supplementation showed significant genoprotective activity on mitochondrial DNA when hydroperoxide was used. The evidence of the protection afforded by quercetin suggests that this flavonoid may play an important role on mitochondrial genome stability.

Alternol inhibits proliferation and induces apoptosis in mouse lymphocyte leukemia (L1210) cells

Alternol is a novel compound purified from the fermenting products by microorganisms named as Alternaria alternata var. monosporus from the bark of Yew. In this study, we tested its effect on mouse lymphocyte leukemia L1210 cells. Alternol was found to inhibit the proliferation and induce apoptosis in L1210 cells. When the cells were treated with Alternol, chromatin condensation and phosphatidylserine externalization were observed with the down-regulation of the pro-survival gene Bcl-2 and the activation of caspase-3, caspase-9, but not caspase-8. Moreover, exposure of cells to Alternol resulted in a significant increase in reactive oxygen species (ROS) and mitochondrial transmembrane potential (DeltaPsim) depolarization. Taken together, these results demonstrate that Alternol is a potent agent in inducing L1210 cells to apoptosis, which involve caspase activation and ROS generation.

Curcumin protects PC12 cells against 1-methyl-4-phenylpyridinium ion-induced apoptosis by bcl-2-mitochondria-ROS-iNOS pathway

The aim of present study is to explore the cytoprotection of curcumin against 1-methyl-4-phenylpridinium ions (MPP(+))-induced apoptosis and the molecular mechanisms underlying in PC12 cells. Our findings indicated that MPP(+) significantly reduced the cell viability and induced apoptosis of PC12 cells. Curcumin protected PC12 cells against MPP(+)-induced cytotoxicity and apoptosis not only by inducing overexpression of Bcl-2, but also reducing the loss of mitochondrial membrane potential (MMP), an increase in intracellular reactive oxygen species (ROS) and overexpression of inducible nitric oxide synthase (iNOS). The selective iNOS inhibitor AG partly blocked MPP(+)-induced apoptosis of PC12 cells. The results of present study suggested that the cytoprotective effects of curcumin might be mediated, at least in part, by the Bcl-2-mitochondria-ROS-iNOS pathway. Because of its non-toxic property, curcumin could be further developed to treat the neurodegenerative diseases which are associated with oxidative stress, such as Parkinson's disease (PD).

Morroniside prevents peroxide-induced apoptosis by induction of endogenous glutathione in human neuroblastoma cells

(1) Morroniside belongs to an extensive group of natural iridorid glycosides. In the present study, using human neuroblastoma SH-SY5Y cells, we have investigated the protective effects of this compound on modifications in endogenous reduced glutathione (GSH), intracellular oxygen species (ROS) and apoptotic death on H(2)O(2)-mediated cytoxicity. (2) Incubation of cells with morroniside led to a significant dose-dependent elevation of cellular GSH accompanied by a marked protection against H(2)O(2)-mediated toxicity. Morroniside at 1-100 microM inhibited the formation of ROS and the activation of caspase-3 and 9, and the upregulation of Bcl-2, whereas no significant change occurred in Bax levels. (3) The results indicated that the anti-oxidative and anti-apoptotic properties render this natural compound potentially protective against H(2)O(2)-induced cytotoxicity. (4) This study suggested that intracellular GSH appeared to be an important factor in morroniside-mediated cytoprotection against H(2)O(2)-toxicity in SH-SY5Y cells.

Oxidative stress, glucose metabolism, and the prevention of type 2 diabetes: pathophysiological insights

With the rising epidemic of type 2 diabetes worldwide, including the United States, the death and disability due to the suboptimal control of cardiovascular disease associated with this epidemic has made prevention of type 2 diabetes emerge as a primary strategic intervention. Several modalities have been assessed in large randomized controlled trials for diabetes prevention such as lifestyle interventions and various pharmacologic agents. Included in these agents are metformin, thiazolidinediones, acarbose, angiotensin converting enzyme inhibitors, as well as angiotensin receptor blockers. Abrogation of oxidative stress appears to be a common soil hypothesis that explains the favorable effects of these agents on glucose metabolism, including the prevention of diabetes and its complications. This comprehensive review highlights the role of oxidative stress in the pathogenesis of diabetes, with emphasis on the major clinical trials conducted on prevention of type 2 diabetes.

Vector-mediated delivery of bcl-2 prevents degeneration of auditory hair cells and neurons after injury

OBJECTIVE

To test the hypothesis that bcl-2 prevents oxidative stress-induced apoptosis of auditory sensory cells in explants of the organ of Corti and dissociated cell cultures of the spiral ganglion.

METHODS

Organ of Corti explants and dissociated spiral ganglion cell cultures obtained from 3-day-old (P3) rats or adult spiral ganglion cell cultures from 28-day-old (P28) rats were transduced with vectors containing a human bcl-2 gene. Cultures were then exposed to neomycin, cisplatin or subjected to withdrawal of neurotrophin supplementation. Outcome measures included hair cell and neuron counts, mitochondrial membrane potential and a histological measure of apoptosis.

RESULTS

Expression of bcl-2 in the organ of Corti explants and neuronal cell cultures provided a significant level of protection against cell death. Bcl-2 expression in the organ of Corti explants also protected mitochondria from loss of membrane potential and blocked an early step in the commitment of hair cells to apoptosis.

CONCLUSION

Expression of bcl-2 in cochlear tissues protects sensory cells from a variety of insults that have been demonstrated to damage the inner ear.

Up-regulation of Bcl-2 in APP transgenic mice is associated with neuroprotection

Abeta-induced neurodegeneration is limited in APP and APP+PS1 transgenic mice. In middle-aged APP + PS1 transgenic mice, we found significantly increased Bcl-2 expression. The increase in Bcl-2 is restricted to amyloid-containing brain regions and is not found at young ages, suggesting that Abeta deposition is the stimulus for increased Bcl-2. Western blot results were confirmed with immunohistochemistry and qRT-PCR. In addition, we found that APP transgenic mice were protected from neurotoxicity caused by an injection of bak BH3 fusion peptides, known to induce apoptosis by antagonizing bcl protein activity. Nissl and fluorojade-stained slides showed that the active bak BH3 peptide caused substantial neuronal loss in the dentate gyrus and CA3 regions of nontransgenic, but not APP mice. The inactive mutant bak BH3 peptide did not cause degeneration in any mice. These data demonstrate that the increased Bcl-2 expression in brain regions containing Abeta deposits is associated with neuroprotection.

Rapid phosphorylation of histone H2A.X following ionotropic glutamate receptor activation

Excessive activation of ionotropic glutamate receptors increases oxidative stress, contributing to the neuronal death observed following neurological insults such as ischemia and seizures. Post-translational histone modifications may be key mediators in the detection and repair of damage resulting from oxidative stress, including DNA damage, and may thus affect neuronal survival in the aftermath of insults characterized by excessive glutamate release. In non-neuronal cells, phosphorylation of histone variant H2A.X (termed gamma-H2AX) occurs rapidly following DNA double-strand breaks. We investigated gamma-H2AX formation in rat cortical neurons (days in vitro 14) following activation of N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate glutamate receptors using fluorescent immunohistochemical techniques. Moreover, we evaluated the co-localization of gamma-H2AX 'foci' with Mre11, a double-strand break repair protein, to provide further evidence for the activation of this DNA damage response pathway. Here we show that minimally cytotoxic stimulation of ionotropic glutamate receptors was sufficient to evoke gamma-H2AX in neurons, and that NMDA-induced gamma-H2AX foci formation was attenuated by pretreatment with the antioxidant, Vitamin E, and the intracellular calcium chelator, BAPTA-AM. Moreover, a subset of gamma-H2AX foci co-localized with Mre11, indicating that at least a portion of gamma-H2AX foci is damage dependent. The extent of gamma-H2AX induction following glutamate receptor activation corresponded to the increases we observed following conventional DNA damaging agents [i.e. non-lethal doses of gamma-radiation (1 Gy) and hydrogen peroxide (10 microm)]. These data suggest that insults not necessarily resulting in neuronal death induce the DNA damage-evoked chromatin modification, gamma-H2AX, and implicate a role for histone alterations in determining neuronal vulnerability following neurological insults.

Role of mitochondrial DNA in toxic responses to oxidative stress

Mitochondria are at the crossroads of several crucial cellular activities including: adenosine triphosphate (ATP) generation via oxidative phosphorylation; the biosynthesis of heme, pyrimidines and steroids; calcium and iron homeostasis and programmed cell death (apoptosis). Mitochondria also produce considerable quantities of superoxide and hydrogen peroxide (H2O2) that in conjunction with its large iron stores can lead to a witch's brew of reactive intermediates capable of damaging macromolecules. Mitochondrial DNA (mtDNA) represents a critical target for such oxidative damage. Once damaged, mtDNA can amplify oxidative stress by decreased expression of critical proteins important for electron transport leading to a vicious cycle of reactive oxygen species (ROS) and organellar dysregulation that eventually trigger apoptosis. Oxidative stress is associated with many human disorders including: cancer, cardiovascular disease, diabetes mellitus, liver disease and neurodegenerative disease. This article reviews the evidence that oxidative damage to mtDNA can culminate in cell death and thus represents an important target for therapeutic intervention in a number of human diseases.

Protective effect of protocatechuic acid from Alpinia oxyphylla on hydrogen peroxide-induced oxidative PC12 cell death

The neuroprotective effects of protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia oxyphylla, on hydrogen peroxide (H(2)O(2))-induced apoptosis and oxidative stress in cultured PC12 cells were investigated. Exposure of PC12 cells to 0.4 mM H(2)O(2) induced a leakage of lactate dehydrogenase (LDH) and decreased cell viability denoted by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PCA increased PC12 cellular viability and markedly attenuated H(2)O(2)-induced apoptotic cell death in a dose-dependent manner. By flow cytometric analysis, PCA showed its significant effect on protecting PC12 cells against H(2)O(2)-induced apoptosis. In these cells, the levels of glutathione (GSH) and activity of catalase were augmented, while glutathione peroxidase activity remained unchanged. In addition, PCA also protected against cell damage induced by H(2)O(2) and Fe(2+), which generated hydroxyl radicals (OH) by the Fenton reaction. These results suggest that PCA may be a candidate chemical for the treatment of oxidative stress-induced neurodegenerative disease.

Two distinct signaling pathways regulate peroxynitrite-induced apoptosis in PC12 cells

The mechanisms of peroxynitrite-induced apoptosis are not fully understood. We report here that peroxynitrite-induced apoptosis of PC12 cells requires the simultaneous activation of p38 and JNK MAP kinase, which in turn activates the intrinsic apoptotic pathway, as evidenced by Bax translocation to the mitochondria, cytochrome c release to the cytoplasm and activation of caspases, leading to cell death. Peroxynitrite induces inactivation of the Akt pathway. Furthermore, overexpression of constitutively active Akt inhibits both peroxynitrite-induced Bax translocation and cell death. Peroxynitrite-induced death was prevented by overexpression of Bcl-2 and by cyclosporin A, implicating the involvement of the intrinsic apoptotic pathway. Selective inhibition of mixed lineage kinase (MLK), p38 or JNK does not attenuate the decrease in Akt phosphorylation showing that inactivation of the Akt pathway occurs independently of the MLK/MAPK pathway. Together, these results reveal that peroxynitrite-induced activation of the intrinsic apoptotic pathway involves interactions with the MLK/MAPK and Akt signaling pathways.

Protection of oxidative preconditioning against apoptosis induced by H2O2 in PC12 cells: mechanisms via MMP, ROS, and Bcl-2

The present study is designed to investigate the effects of preconditioning with different doses of hydrogen peroxide (H2O2) on oxidative stress-induced apoptosis and the changes in mitochondrial membrane potential (MMP), intracellular reactive oxygen species (ROS) level, and expression of Bcl-2 during H2O2 preconditioning in rat pheochromocytoma (PC12) cells. It was shown that (1) H2O2 induced apoptosis in PC12 cells in a dose-dependent manner; (2) the preconditioning with 10 micromol L(-1) or 20 micromol L(-1) H2O2 can significantly protect PC12 cells against apoptosis induced by 50 or 100 micromol L(-1) H2O2, low (5 micromol L(-1)) and higher (30 micromol L(-1)) concentrations of H2O2 had no cytoprotections; (3) high concentration (100 micromol L(-1)) of H2O2 reduced MMP and expression of Bcl-2, and increased ROS level, but these effects were blocked by preconditioning with 10 micromol L(-1) H2O2; (4) the preconditioning with 10 micromol L(-1) H2O2 induced overexpression of Bcl-2. These results suggested that the preconditioning with low dose of H2O2 could protect the oxidative stress-induced PC12 cells apoptosis not only by preventing the reduction of MMP and expression of Bcl-2 as well as increase in ROS level, but also through overexpression of Bcl-2. It was indicated that overexpression of Bcl-2 may play a key role in the cytoprotection induced by preconditioning with low dose of H2O2 in PC12 cells.

3-nitropropionic acid-induced hydrogen peroxide, mitochondrial DNA damage, and cell death are attenuated by Bcl-2 overexpression in PC12 cells

3-nitropropionic acid (3-NPA), a complex II inhibitor of the electron transport chain, causes Huntington disease-like symptoms after administration into animals. However, primary mechanisms of cell death are not clearly understood. This study tested the hypothesis that 3-NPA leads to the generation of reactive oxygen species (ROS), mitochondrial DNA damage, and loss of mitochondrial function. Amplex red and horseradish peroxidase were used to accurately measure the amount of H2O2, and showed that PC12 cells treated with 3-NPA (4 mM) lead to the production of hydrogen peroxide (1 nmol/10(6) cells/h). This amount of 3-NPA also leads to a rapid decline of ATP levels. There was time- and dose-dependent mitochondrial DNA damage following 3-NPA treatment. Overexpression of the proto-oncogene bcl-2 protects cells from apoptosis induced by various stimuli. Overexpression of Bcl-2 leads to almost threefold higher levels of ATP and also decreased the 3-NPA-mediated induction of hydrogen peroxide by over 50%. Bcl-2-overexpressing PC12 cells were also protected from mitochondrial DNA damage. These data show that ROS production followed by mitochondrial DNA damage is the primary event in 3-NPA toxicity, and Bcl-2 protects PC12 cells from 3-NPA toxicity by preventing mitochondrial DNA damage.

Strawberry and its anthocyanins reduce oxidative stress-induced apoptosis in PC12 cells

Because strawberries are known to contain higher concentrations of phytochemicals and have higher antioxidant capacity among common fruits, their neuroprotective activity was tested in vitro on PC12 cells treated with H2O2. Their protective effect and antioxidant capacity were also compared with those of banana and orange, which are the fresh fruits consumed at highest levels in the United States. The cell viability test using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay showed that strawberry phenolics significantly reduced oxidative stress-induced neurotoxicity. Because oxidative stress is also known to increase neuronal cell membrane breakdown, lactate dehydrogenase (LDH) and trypan blue exclusion assays were also performed. Strawberry showed the highest cell protective effects among the samples. The overall relative neuronal cell protective activity of three fruits by three tests followed the decreasing order strawberry > banana > orange. The protective effects appeared to be due to the higher phenolic contents including anthocyanins, and anthocyanins in strawberries seemed to be the major contributors.

Nicotinic acetylcholine receptor immunohistochemistry in Alzheimer's disease and dementia with Lewy bodies: differential neuronal and astroglial pathology

Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are common forms of dementia in the elderly. The neuropathology of AD and DLB is related to cholinergic dysfunctions, and both alpha4 and alpha7 nicotinic acetylcholine receptor (nAChR) subunits are decreased in several brain areas in both diseases. In this immunohistochemical study, we compared neuronal and astroglial alpha4 and alpha7 subunits in AD, DLB and age-matched controls in the hippocampal formation. The numbers of alpha4 reactive neurons were decreased in layer 3 of the entorhinal cortex of AD and DLB, whereas those of alpha7 reactive neurons were decreased in layer 2 of the subiculum of AD and DLB and in layer 3 of the entorhinal cortex of DLB. In contrast, the intensity of alpha7 reactive neuropil was significantly higher in AD than in controls or DLB in a number of areas of the hippocampus (CA3/4 and stratum granulosum), subiculum and entorhinal cortex. An increase in alpha7 immunoreactivity in AD was also associated with astrocytes. The number of astrocytes double-labelled with alpha7 and glial fibrillary acidic protein (GFAP) antibodies was increased in most areas of the hippocampus and entorhinal cortex in AD compared with controls and DLB. Increased astrocyte alpha7 nAChRs in AD may be associated with inflammatory mechanisms related to degenerative processes specific to this disease.

Oxidative stress in the pathogenesis of diabetic neuropathy

Oxidative stress results from a cell or tissue failing to detoxify the free radicals that are produced during metabolic activity. Diabetes is characterized by chronic hyperglycemia that produces dysregulation of cellular metabolism. This review explores the concept that diabetes overloads glucose metabolic pathways, resulting in excess free radical production and oxidative stress. Evidence is presented to support the idea that both chronic and acute hyperglycemia cause oxidative stress in the peripheral nervous system that can promote the development of diabetic neuropathy. Proteins that are damaged by oxidative stress have decreased biological activity leading to loss of energy metabolism, cell signaling, transport, and, ultimately, to cell death. Examination of the data from animal and cell culture models of diabetes, as well as clinical trials of antioxidants, strongly implicates hyperglycemia-induced oxidative stress in diabetic neuropathy. We conclude that striving for superior antioxidative therapies remains essential for the prevention of neuropathy in diabetic patients.