Antioxidants in multiple sclerosis: do they have a role in therapy?

Comparative Neuroprotective Potential of Nanoformulated and Free Resveratrol Against Cuprizone-Induced Demyelination in Rats

Demyelination is a frequent yet crippling neurological disease associated with multiple sclerosis (MS). The cuprizone (CZ) model, which causes demyelination through oxidative stress and neuroinflammation, is a popular tool used by researchers to examine this process. The polyphenol resveratrol (RESV) has become a promising neuroprotective agent in seeking for efficient therapies. In a rat model given CZ, we created and examined iron oxide nanoparticles (IONPs) loaded with RESV (IONP-RESV) to see how effective they were as a therapeutic agent against free RESV. According to molecular mechanisms, exposure to CZ resulted in a marked downregulation of myelin proteolipid protein (PLP) expression and an overexpression of the inflammatory markers tumor necrosis factor-α (TNF-α) and S100β, which are indicators of demyelination and neuroinflammation. It is remarkable that these CZ-induced alterations could be reversed by therapy with either RESV or IONP-RESV. Interestingly, IONP-RESV showed even stronger anti-inflammatory activity, as shown by a more noticeable downregulation of TNF-α and S100β expression. These results were confirmed by histopathological examination of the cerebral cortices. Our findings support the better neuroprotective benefits of RESV-loaded IONPs over free RESV in reducing demyelination and neuroinflammation brought on by CZ. Owing to their pro-remyelinating, anti-inflammatory, and antioxidant properties, RESV-loaded IONPs show promise as a neurotherapeutic intervention in the future for neurological diseases such as multiple sclerosis.

The role of reactive oxygen species in the regulation of the blood-brain barrier

The blood-brain barrier (BBB) regulates the exchange of metabolites and cells between the blood and brain, and maintains central nervous system homeostasis. Various factors affect BBB barrier functions, including reactive oxygen species (ROS). ROS can act as stressors, damaging biological molecules, but they also serve as secondary messengers in intracellular signaling cascades during redox signaling. The impact of ROS on the BBB has been observed in multiple sclerosis, stroke, trauma, and other neurological disorders, making blocking ROS generation a promising therapeutic strategy for BBB dysfunction. However, it is important to consider ROS generation during normal BBB functioning for signaling purposes. This review summarizes data on proteins expressed by BBB cells that can be targets of redox signaling or oxidative stress. It also provides examples of signaling molecules whose impact may cause ROS generation in the BBB, as well as discusses the most common diseases associated with BBB dysfunction and excessive ROS generation, open questions that arise in the study of this problem, and possible ways to overcome them.

Neuroprotective effects of rutin against cuprizone-induced multiple sclerosis in mice

Multiple sclerosis (MS) is a chronic inflammatory neurodegenerative disease of the central nervous system that injures the myelin sheath, provoking progressive axonal degeneration and functional impairments. No efficient therapy is available at present to combat such insults, and hence, novel safe and effective alternatives for MS therapy are extremely required. Rutin (RUT) is a flavonoid that exhibits antioxidant, anti-inflammatory, and neuroprotective effects in several brain injuries. The present study evaluated the potential beneficial effects of two doses of RUT in a model of pattern-III lesion of MS, in comparison to the conventional standard drug; dimethyl fumarate (DMF). Demyelination was induced in in male adult C57BL/6 mice by dietary 0.2% (w/w) cuprizone (CPZ) feeding for 6 consecutive weeks. Treated groups received either oral RUT (50 or 100 mg/kg) or DMF (15 mg/kg), along with CPZ feeding, for 6 consecutive weeks. Mice were then tested for behavioral changes, followed by biochemical analyses and histological examinations of the corpus callosum (CC). Results revealed that CPZ caused motor dysfunction, demyelination, and glial activation in demyelinated lesions, as well as significant oxidative stress, and proinflammatory cytokine elevation. Six weeks of RUT treatment significantly improved locomotor activity and motor coordination. Moreover, RUT considerably improved remyelination in the CC of CPZ + RUT-treated mice, as revealed by luxol fast blue staining and transmission electron microscopy. Rutin also significantly attenuated CPZ-induced oxidative stress and inflammation in the CC of tested animals. The effect of RUT100 was obviously more marked than either that of DMF, regarding most of the tested parameters, or even its smaller tested dose. In silico docking revealed that RUT binds tightly within NF-κB at the binding site of the protein-DNA complex, with a good negative score of -6.79 kcal/mol. Also, RUT-Kelch-like ECH-associated protein 1 (Keap1) model clarifies the possible inhibition of Keap1-Nrf2 protein-protein interaction. Findings of the current study provide evidence for the protective effect of RUT in CPZ-induced demyelination and behavioral dysfunction in mice, possibly by modulating NF-κB and Nrf2 signaling pathways. The present study may be one of the first to indicate a pro-remyelinating effect for RUT, which might represent a potential additive benefit in treating MS.

Neuroprotection by acrolein sequestration through exogenously applied scavengers and endogenous enzymatic enabling strategies in mouse EAE model

We have previously shown that the pro-oxidative aldehyde acrolein is a critical factor in MS pathology. In this study, we found that the acrolein scavenger hydralazine (HZ), when applied from the day of induction, can suppress acrolein and alleviate motor and sensory deficits in a mouse experimental autoimmune encephalomyelitis (EAE) model. Furthermore, we also demonstrated that HZ can alleviate motor deficits when applied after the emergence of MS symptoms, making potential anti-acrolein treatment a more clinically relevant strategy. In addition, HZ can reduce both acrolein and MPO, suggesting a connection between acrolein and inflammation. We also found that in addition to HZ, phenelzine (PZ), a structurally distinct acrolein scavenger, can mitigate motor deficits in EAE when applied from the day of induction. This suggests that the likely chief factor of neuroprotection offered by these two structurally distinct acrolein scavengers in EAE is their common feature of acrolein neutralization. Finally, up-and-down regulation of the function of aldehyde dehydrogenase 2 (ALDH2) in EAE mice using either a pharmacological or genetic strategy led to correspondent motor and sensory changes. This data indicates a potential key role of ALDH2 in influencing acrolein levels, oxidative stress, inflammation, and behavior in EAE. These findings further consolidate the critical role of aldehydes in the pathology of EAE and its mechanisms of regulation. This is expected to reinforce and expand the possible therapeutic targets of anti-aldehyde treatment to achieve neuroprotection through both endogenous and exogenous manners.

Role of fenofibrate in multiple sclerosis

Multiple sclerosis (MS) is the most frequent inflammatory and demyelinating disease of the central nervous system (CNS). The underlying pathophysiology of MS is the destruction of myelin sheath by immune cells. The formation of myelin plaques, inflammation, and injury of neuronal myelin sheath characterizes its neuropathology. MS plaques are multiple focal regions of demyelination disseminated in the brain's white matter, spinal cords, deep grey matter, and cerebral cortex. Fenofibrate is a peroxisome proliferative activated receptor alpha (PPAR-α) that attenuates the inflammatory reactions in MS. Fenofibrate inhibits differentiation of Th17 by inhibiting the expression of pro-inflammatory signaling. According to these findings, this review intended to illuminate the mechanistic immunoinflammatory role of fenofibrate in mitigating MS neuropathology. In conclusion, fenofibrate can attenuate MS neuropathology by modulating different pathways, including oxidative stress, autophagy, mitochondrial dysfunction, inflammatory-signaling pathways, and neuroinflammation.

A comprehensive in silico analysis of multiple sclerosis related non-synonymous SNPs and their potential effects on protein structure and function

BACKGROUND

Multiple Sclerosis (MS) is an autoimmune and central nervous system disease characterized by an inflammatory demyelinating process in the brain. Although the exact cause of MS is still unclear, environmental, and genetic factors are known to play a role in the development of disease. New molecular markers must be identified to understand the mechanism of disease formation and progression. We investigated the effects of MS-related non-synonymous single-nucleotide polymorphisms (nsSNPs) on the structure and function of identified proteins in this study.

METHODS

Missense variations associated with MS were extracted from the NHGRI-EBI GWAS database. Functional and structural analysis of nsSNPs on mapped genes was performed using g:Profiler, Wikipathway, KEGG, Reactome and Gene ontology programs (p < 0.05 was accepted statistically significant). Amino acid sequence-based analysis was performed to identify deleterious variants by using PROVEAN and PredictSNP tools. Finally, protein structure analyzes were performed on deleterious protein variants by DynaMut, Mutabind2 and Missense3D servers to identify changes in protein stability and flexibility.

RESULTS

10 target nsSNPs were identified. Among these rs34536443, rs10936599, rs2293152, rs11808092, rs1129183 were found deleterious according to amino acid sequence-based analysis. Furthermore, structure-based analyses show that TYK2 (P1104A), MYNN (H6Q), EVI5 (Q612H), and LZTFL1 (D246N) substitutions increase protein stability and decrease structure flexibility, whereas STAT3 (R426G) substitution decreases protein stability and increases structure flexibility.

CONCLUSION

We revealed that identified nsSNPs have potential effects on stability and flexibility of the target proteins. The prominent target genes are thought to have significant impacts on the pathogenesis of MS. Further in vitro and in vivo studies are required to validate our in silico results.

Rg3-enriched Korean Red Ginseng extract inhibits blood-brain barrier disruption in an animal model of multiple sclerosis by modulating expression of NADPH oxidase 2 and 4

Background

Multiple sclerosis (MS) and its animal model, the experimental autoimmune encephalomyelitis (EAE), are primarily characterized as dysfunction of the blood-brain barrier (BBB). Ginsenoside-Rg3-enriched Korean Red Ginseng extract (Rg3-KRGE) is known to exert neuroprotective, anti-inflammatory, and anti-oxidative effects on neurological disorders. However, effects of Rg3-KRGE in EAE remain unclear.

Methods

Here, we investigated whether Rg3-KRGE may improve the symptoms and pathological features of myelin oligodendroglial glycoprotein (MOG)_35-55 peptide – induced chronic EAE mice through improving the integrity of the BBB.

Results

Rg3-KRGE decreased EAE score and spinal demyelination. Rg3-KRGE inhibited Evan's blue dye leakage in spinal cord, suppressed increases of adhesion molecule platelet endothelial cell adhesion molecule-1, extracellular matrix proteins fibronection, and matrix metallopeptidase-9, and prevented decreases of tight junction proteins zonula occludens-1, claudin-3, and claudin-5 in spinal cord following EAE induction. Rg3-KRGE repressed increases of proinflammatory transcripts cyclooxygenase-2, inducible nitric oxide synthase, interleukin (IL)-1 beta, IL-6, and tumor necrosis factor-alpha, but enhanced expression levels of anti-inflammatory transcripts arginase-1 and IL-10 in the spinal cord following EAE induction. Rg3-KRGE inhibited the expression of oxidative stress markers (MitoSOX and 4-hydroxynonenal), the enhancement of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and NOX4, and NADPH activity in the spinal cord of chronic EAE mice. Furthermore, apocynin, a NOX inhibitor, mimicked beneficial effects of Rg3-KRGE in chronic EAE mice.

Conclusion

Our findings suggest that Rg3-KRGE might alleviate behavioral symptoms and pathological features of MS by improving BBB integrity through modulation of NOX2/4 expression.

Towards a comprehensive etiopathogenetic and pathophysiological theory of multiple sclerosis

Background: Multiple sclerosis (MS) is a neurodegenerative disease caused by dysfunction of the immune system that affects the central nervous system (CNS). It is characterized by demyelination, chronic inflammation, neuronal and oligodendrocyte loss and reactive astrogliosis. It can result in physical disability and acute neurological and cognitive problems. Despite the gains in knowledge of immunology, cell biology, and genetics in the last five decades, the ultimate etiology or specific elements that trigger MS remain unknown. The objective of this review is to propose a theoretical basis for MS etiopathogenesis.Methods: Search was done by accessing PubMed/Medline, EBSCO, and PsycINFO databases. The search string used was "(multiple sclerosis* OR EAE) AND (pathophysiology* OR etiopathogenesis)". The electronic databases were searched for titles or abstracts containing these terms in all published articles between January 1, 1960, and June 30, 2019. The search was filtered down to 362 articles which were included in this review.Results: A framework to better understand the etiopathogenesis and pathophysiology of MS can be derived from four essential factors; mitochondria dysfunction (MtD) & oxidative stress (OS), vitamin D (VD), sex hormones and thyroid hormones. These factors play a direct role in MS etiopathogenesis and have a modulatory effect on many other factors involved in the disease.Conclusions: For better MS prevention and treatment outcomes, efforts should be geared towards treating thyroid problems, sex hormone alterations, VD deficiency, sleep problems and melatonin alterations. MS patients should be encouraged to engage in activities that boost total antioxidant capacity (TAC) including diet and regular exercise and discouraged from activities that promote OS including smoking and alcohol consumption.

A review on potential roles of vitamins in incidence, progression, and improvement of multiple sclerosis

Multiple Sclerosis (MS) is an inflammatory and neurodegenerative disease, with unknown etiology. Vitamins, as important micronutrients playing different roles in body, seem to be important in MS pathogenesis. In vitro, in vivo and human studies, supports the protective role of some vitamins in MS occurrence or progression. Current study reviews recent insights and reports about the importance of vitamins in MS incidence or progression. In accordance, the importance of all water and fat-soluble vitamins in MS pathogenesis based on observational studies in human population and their role in the function of immune system as well as possible therapeutic opportunities are discussed in depth throughout this review.

Modulating inflammation and neuroprotection in multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder of the central nervous system with a presentation and disease course that is largely unpredictable. MS can cause loss of balance, impaired vision or speech, weakness and paralysis, fatigue, depression, and cognitive impairment. Immunomodulation is a major target given the appearance of focal demyelinating lesions in myelin-rich white matter, yet progression and an increasing appreciation for gray matter involvement, even during the earliest phases of the disease, highlights the need to afford neuroprotection and limit neurodegenerative processes that correlate with disability. This review summarizes key aspects of MS pathophysiology and histopathology with a focus on neuroimmune interactions in MS, which may facilitate neurodegeneration through both direct and indirect mechanisms. There is a focus on processes thought to influence disease progression and the role of oxidative stress and mitochondrial dysfunction in MS. The goals and efficacy of current disease-modifying therapies and those in the pipeline are discussed, highlighting recent advances in our understanding of pathways mediating disease progression to identify and translate both immunomodulatory and neuroprotective therapeutics from the bench to the clinic.

In vivo evidence of oxidative stress in brains of patients with progressive multiple sclerosis

BACKGROUND

The oxidative stress hypothesis links neurodegeneration in the later, progressive stages of multiple sclerosis (MS) to the loss of a major brain antioxidant, glutathione (GSH).

OBJECTIVE

We measured GSH concentrations among major MS subtypes and examined the relationships with other indices of disease status including physical disability and magnetic resonance imaging (MRI) measures.

METHODS

GSH mapping was performed on the fronto-parietal region of patients with relapsing-remitting multiple sclerosis (RRMS, n = 21), primary progressive multiple sclerosis (PPMS, n = 20), secondary progressive multiple sclerosis (SPMS, n = 20), and controls ( n = 28) using GSH chemical shift imaging. Between-group comparisons were performed on all variables (GSH, T2-lesion, atrophy, Expanded Disability Status Scale (EDSS)).

RESULTS

Patients with MS had substantially lower GSH concentrations than controls, and GSH was lower in progressive MS (PPMS and SPMS) compared with RRMS. GSH concentrations were not significantly different between PPMS and SPMS, or between RRMS and controls. Brain atrophy was significant in both RRMS and progressive MS compared with controls.

CONCLUSION

Markedly lower GSH in progressive MS than RRMS indicates more prominent involvement of oxidative stress in the progressive stage of MS than the inflammatory stage. The association between GSH and brain atrophy suggests the important role of oxidative stress contributing to neurodegeneration in progressive MS, as suggested in other neurodegenerative diseases.

Oral administration of the nitroxide radical TEMPOL exhibits immunomodulatory and therapeutic properties in multiple sclerosis models

Therapies with both immunomodulatory and neuroprotective properties are thought to have the greatest promise in reducing the severity and progression of multiple sclerosis (MS). Several reactive oxygen (ROS) and reactive nitrogen species (RNS) are implicated in inflammatory-mediated damage to the central nervous system (CNS) in MS and its animal model, experimental autoimmune encephalomyelitis (EAE). TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl) is a stable nitroxide radical with potent antioxidant activity. The goal of our studies was to investigate the immunomodulatory effects and therapeutic potential of orally-delivered TEMPOL in the mouse EAE model. Mice receiving TEMPOL chow ad libitum for 2weeks prior to induction of active EAE showed delayed onset and reduced incidence of disease compared to control-fed animals. Reduced disease severity was associated with limited microglial activation and fewer inflammatory infiltrates. TEMPOL's effects were immunomodulatory, not immunosuppressive: T cells produced less interferon-γ and tumor necrosis factor-α, and TEMPOL-fed mice exhibited a shift towards T_H2-type antibody responses. Both myeloid and myeloid-dendritic cells of TEMPOL-fed EAE animals had significantly lower levels of MHC class II expression than controls; CD40 was also significantly reduced. TEMPOL administration was associated with an enrichment of CD8⁺ T cell populations and CD4⁺FoxP₃⁺ regulatory populations. TEMPOL reduced the severity of clinical disease when administered after the induction of disease, and also after the onset of clinical symptoms. To exclude effects on T cell priming in vivo, TEMPOL was tested with the passive transfer of encephalitogenic T cells and was found to reduce the incidence and peak severity of disease. Protection was associated with reduced infiltrates and a relative sparing of neurofilaments and axons. The ability of oral TEMPOL to reduce inflammation and axonal damage and loss demonstrate both anti-inflammatory and protective properties, with significant promise for the treatment of MS and related neurological disorders.

Pathophysiological Concepts in Multiple Sclerosis and the Therapeutic Effects of Hydrogen Sulfide

Introduction:

Multiple sclerosis (MS) is generally known as a manageable but not yet curable autoimmune disease affecting central nervous system. A potential therapeutic approach should possess several properties: Prevent immune system from damaging the brain and spinal cord, promote differentiation of oligodendrocyte progenitor cells (OPCs) into mature oligodendrocytes to produce myelin, prevent the formation of fibronectin aggregates by astrocytes to inhibit scar formation, and enhance function of healthy endothelial cells (ECs).

Methods:

To determine if an increase in sulfur contents through H2S, a potent antioxidant known to induce protective autophagy in cells, could provide the above desired outcomes, peripheral blood mononuclear cells (PBMNCs), OCPs, astrocytes, and ECs were treated with NaHS (50 μM) in vitro.

Results:

Transmigration assay using EC monolayer showed that serotonin increased migration of PBMNC while pretreatment of EC with NaHS inhibited the migration induced by serotonin treatment. NaHS upregulated proteins involved in immune system response and downregulated PBMNCs- and EC-related adhesion molecules (LFA-1 and VCAM-1). Furthermore, it had a cell expansion inducing effect, altering EC morphology. The effects of NaHS on OPCs and astrocytes were studied compared to mTOR inhibitor rapamycin. In NaHS treated astrocytes the induced fibronectin production was partially inhibited while rapamycin almost fully inhibited fibronectin production. NaHS slowed but did not inhibit the differentiation of OCPs or the production of myelin compared to rapamycin.

Conclusion:

The in vitro results point to the potential therapeutic application of hydrogen sulfide releasing molecules or health-promoting sulfur compounds in MS.

Resveratrol Promotes Remyelination in Cuprizone Model of Multiple Sclerosis: Biochemical and Histological Study

Multiple sclerosis (MS) is a demyelinating neurodegenerative disease, representing a major cause of neurological disability in young adults. Resveratrol is a stilbenoid polyphenol, known to pass blood brain barrier and exhibit antioxidant, anti-inflammatory, and neuroprotective effects in several brain injuries. Cuprizone model of MS is particularly beneficial in studying demyelination/remyelination. Our study examined the potential neuroprotective and pro-remyelination effects of resveratrol in cuprizone-intoxicated C57Bl/6 mice. Mice were fed with chow containing 0.7 % cuprizone for 7 days, followed by 3 weeks on 0.2 % cuprizone diet. Resveratrol (250 mg/kg/day, p.o.) was given for 3 weeks starting from the second week. At the end of the experiment, animals were tested on rotarod to evaluate changes in balance and motor coordination. Mice were then sacrificed to measure the brain content of glutathione, lipid peroxidation products, adenosine triphosphate, and phospho-inhibitory subunit of nuclear factor κB-α. The activities of cytochrome oxidase and superoxide dismutase were also assessed. The gene expression of myelin basic protein, 2',3'-cyclic nucleotide 3' phosphodiesterase, oligodendrocyte transcription factor-1 (Olig1), NF-κB p65 subunit, and tumor necrosis factor-α was also estimated. Luxol fast blue/periodic acid-Schiff stained brain sections were blindly scored to assess the myelin status. Resveratrol effectively enhanced motor coordination and balance, reversed cuprizone-induced demyelination, improved mitochondrial function, alleviated oxidative stress, and inhibited NF-κB signaling. Interestingly, resveratrol increased Olig1 expression that is positively correlated to active remyelination. The present study may be the first to indicate a pro-remyelinative effect for resveratrol which might represent a potential additive benefit in treating MS.

Ozone Therapy in Ethidium Bromide-Induced Demyelination in Rats: Possible Protective Effect

Multiple sclerosis, an autoimmune inflammatory disease of the central nervous system, is characterized by excessive demyelination. The study aimed to investigate the possible protective effect of ozone (O3) therapy in ethidium bromide (EB)-induced demyelination in rats either alone or in combination with corticosteroids in order to decrease the dose of steroid therapy. Rats were divided into Group (1) normal control rats received saline, Group (2) Sham-operated rats received saline, Group (3) Sham-operated rats received vehicle (oxygen), Group (4) EB-treated rats received EB, Group (5) EB-treated rats received O3, Group (6) EB-treated rats received methylprednisolone (MP), and Group (7) EB-treated rats received half the dose of MP concomitant with O3. EB-treated rats showed a significant increase in the number of footfalls in the grid walk test, decreased brain GSH, and paraoxonase-1 enzyme activity, whereas brain MDA, TNF-α, IL-1β, INF-γ, Cox-2 immunoreactivity, and p53 protein levels were increased. A significant decline in brain serotonin, dopamine, norepinephrine, and MBP immunoreactivity was also reported. Significant improvement of the above-mentioned parameters was demonstrated with the administration of either MP or O3, whereas best amelioration was achieved by combining half the dose of MP with ozone.

A non-synonymous single-nucleotide polymorphism associated with multiple sclerosis risk affects the EVI5 interactome

Despite recent progress in the characterization of genetic loci associated with multiple sclerosis (MS) risk, the ubiquitous linkage disequilibrium operating across the genome has stalled efforts to distinguish causative variants from proxy single-nucleotide polymorphisms (SNPs). Here, we have identified through fine mapping and meta-analysis EVI5 as the most plausible disease risk gene within the 1p22.1 locus. We further show that an exonic SNP associated with risk induces changes in superficial hydrophobicity patterns of the coiled-coil domain of EVI5, which, in turns, affects the EVI5 interactome. Immunoprecipitation of wild-type and mutated EVI5 followed by mass spectrometry generated a roster of disease-specific interactors functionally linked to lipid metabolism. Among the exclusive binding partners of the risk variant, we describe the novel interaction with sphingosine 1-phosphate lyase (SGPL1)-a key enzyme for the creation of the sphingosine-1 phosphate gradient, which is relevant to the pathogenic process and therapeutic management of MS.

Effect of intrahippocampal administration of vitamin C and progesterone on learning in a model of multiple sclerosis in rats

PURPOSE

The purpose of this study was to evaluate the effect of intrahippocampal injection of vitamin C and progesterone, alone or in combination, on passive avoidance learning (PAL) in multiple sclerosis.

METHODS

Sixty- three male wistar rats were divided into nine groups (n=7) as following: control (saline), lesion, vitamin C (0.2, 1, 5 mg/kg), progesterone (0.01, 0.1, 1 µg/µl) and combination therapy. Lesion was induced by intrahippocampal injection of ethidium bromide. In combination therapy, animals were treated with vitamin C (5 mg/kg) plus progesterone (0.01 mg/kg). Animals in experimental groups received different treatments for 7 days, and then all groups were tested for step through latency (STL).

RESULTS

Our results showed that intrahippocampal injection of ethidium bromide destroys PAL significantly (p<0.001). Treatment with vitamin C (5mg/kg) significantly (p<0.05) improved PAL. Lower doses of progesterone did not affect latency but dose of 1 µg/µl significantly (p<0.05) increased STL. In combination therapy group STL was significantly (p<0.05) more than in the lesion group, although it was not significantly different from the vitamin C group.

CONCLUSION

Based on our results, we concluded that intrahippocampal injection of vitamin C improves memory for PAL, but progesterone alone or in combination with vitamin C had no improving effects on memory.

[Antioxidant use as dietary therapy in patients with multiple sclerosis]

INTRODUCTION

Multiple sclerosis is an immune-mediated disease that produces chronic inflammation and neural degeneration. The disease progresses with acute attacks that result in myelin inflammation. This in turn increases oxidative stress and favors the appearance of reactive oxygen species. Reactive oxygen species damage neural cells causing apoptosis. The etiology of multiple sclerosis remains unknown and current therapy is aggressive and expensive. Recently, complementary and alternative medicine therapies have been proposed to control pathogenesis and symptoms of this disease. It is believed that these therapies help slow the progression of multiple sclerosis and improve survival.

METHODS

We conducted a MEDLINE/PubMed search using the following MeSH terms: diet, multiple sclerosis, antioxidants. We selected the main articles containing multiple sclerosis and diet.

RESULTS

We analyzed three case control studies that evaluated different dietary approaches in multiple sclerosis. For this review, we also included five experimental studies that studied the efficacy of lipoic acid in humans and rodents in diseases like multiple sclerosis, experimental autoimmune encephalomyelitis, and breast cancer.

Multiple sclerosis: molecular mechanisms and therapeutic opportunities

The pathophysiology of multiple sclerosis (MS) involves several components: redox, inflammatory/autoimmune, vascular, and neurodegenerative. All of them are supported by the intertwined lines of evidence, and none of them should be written off. However, the exact mechanisms of MS initiation, its development, and progression are still elusive, despite the impressive pace by which the data on MS are accumulating. In this review, we will try to integrate the current facts and concepts, focusing on the role of redox changes and various reactive species in MS. Knowing the schedule of initial changes in pathogenic factors and the key turning points, as well as understanding the redox processes involved in MS pathogenesis is the way to enable MS prevention, early treatment, and the development of therapies that target specific pathophysiological components of the heterogeneous mechanisms of MS, which could alleviate the symptoms and hopefully stop MS. Pertinent to this, we will outline (i) redox processes involved in MS initiation; (ii) the role of reactive species in inflammation; (iii) prooxidative changes responsible for neurodegeneration; and (iv) the potential of antioxidative therapy.

Effect of lipoic acid consumption on oxidative stress among multiple sclerosis patients: a randomized controlled clinical trial

OBJECTIVES

Multiple sclerosis is a neurodegenerative and demyelinating disease of central nervous system. High levels of oxidative stress are associated with inflammation and play an important role in pathogenesis of multiple sclerosis. This double-blind, randomized controlled clinical study was carried out to determine the effect of daily consumption of lipoic acid on oxidative stress among multiple sclerosis patients.

METHODS

A total of 52 relapsing-remitting multiple sclerosis patients, aged 18-50 years with Expanded Disability Status Scale ≤5.5 were assigned to consume either lipoic acid (1200 mg/day) or placebo capsules for 12 weeks. Fasting blood samples were collected before the first dose taken and 12 hours after the last. Dietary intakes were obtained by using 3-day dietary records.

RESULTS

Consumption of lipoic acid resulted in a significant improvement of total antioxidant capacity (TAC) in comparison to the placebo group (P = 0.004). Although a significant change of TAC (-1511 mmol/L, P = 0.001) was found within lipoic acid group, other markers of oxidative stress including superoxide dismutase activity, glutathione peroxidase activity, and malondialdehyde levels were not affected by lipoic acid consumption.

DISCUSSION

These results suggest that 1200 mg of lipoic acid improves serum TAC among multiple sclerosis patients but does not affect other markers of oxidative stress.

Copper-zinc superoxide dismutase-deficient mice show increased susceptibility to experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein 35-55

In this report, we have addressed the role of copper-zinc superoxide dismutase (SOD1) deficiency in the mediation of central nervous system autoimmunity. We demonstrate that SOD1-deficient C57Bl/6 mice develop more severe autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein (MOG) 35-55, compared with wild type mice. This alteration in the disease phenotype was not due to aberrant expansion of MOG-specific T cells nor their ability to produce inflammatory cytokines; rather lymphocytes generated in SOD1-deficient mice were more prone to spontaneous cell death when compared with their wild type littermate controls. The data point to a role for SOD1 in the maintenance of self-tolerance leading to the suppression of autoimmune responses.

One-pot three-component synthesis of novel heterocyclic steroids as a central antioxidant and anti-inflammatory agents

Oxidative stress and inflammation have been implicated in several neurodegenerative and developmental brain disorders. The present work was devoted to the design and synthesis of novel steroid derivatives bearing promising heterocyclic moiety that would act to reduce neuro-inflammation and oxidative stress in brain. The novel heterocyclic steroids were synthesized and their chemical structures were confirmed by studying their analytical and spectral data. The tested compounds were assayed in the model of neuro-inflammation produced in rats by cerebral lipopolysaccharide injection. The intracerebral administration of bacterial endotoxin resulted in cerebral inflammatory state evidenced by increased malondialdehyde (MDA), decreased reduced glutathione (GSH) level, increased nitric oxide as well as increased acetylcholinesterase (AChE) activity in the brain. Compounds 6, 10, 8b and 13a markedly increased reduced glutathione. Malondialadehyde and nitric oxide levels were reduced to normal values after treatment with all tested compounds. AChE activity was normalized by compound 8b and reduced to below normal values by compounds 10 and 14a. These results are exciting in that these agents might be useful candidates in treatment of cerebral inflammation.

Cannabinoids, multiple sclerosis and neuroprotection

The cannabinoid signaling system participates in the control of cell homeostasis in the CNS, which explains why, in different neurodegenerative diseases including multiple sclerosis (MS), alterations in this system have been found to serve both as a pathogenic factor (malfunctioning of this system has been found at early phases of these diseases) and as a therapeutic target (the management of this system has beneficial effects). MS is an autoimmune disease that affects the CNS and it is characterized by inflammation, demyelination, remyelination, gliosis and axonal damage. Although it has been considered mainly as an inflammatory disorder, recent studies have recognized the importance of axonal loss both in the progression of the disorder and in the appearance of neurological disability, even in early stages of the disease. In recent years, several laboratories have addressed the therapeutic potential of cannabinoids in MS, given the experience reported by some MS patients who self-medicated with marijuana. Most of these studies focused on the alleviation of symptoms (spasticity, tremor, anxiety and pain) or on the inflammatory component of the disease. However, recent data also revealed the important neuroprotective action that could be exerted by cannabinoids in this disorder. The present review will be precisely centered on this neuroprotective potential, which is based mainly on antioxidant, anti-inflammatory and anti-excitotoxic properties, exerted through the activation of CB1 or CB2 receptors or other unknown mechanisms.

Cannabinoid receptor signalling in neurodegenerative diseases: a potential role for membrane fluidity disturbance

Type-1 cannabinoid receptor (CB(1)) is the most abundant G-protein-coupled receptor (GPCR) in the brain. CB(1) and its endogenous agonists, the so-called 'endocannabinoids (eCBs)', belong to an ancient neurosignalling system that plays important functions in neurodegenerative and neuroinflammatory disorders like Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and multiple sclerosis. For this reason, research on the therapeutic potential of drugs modulating the endogenous tone of eCBs is very intense. Several GPCRs reside within subdomains of the plasma membranes that contain high concentrations of cholesterol: the lipid rafts. Here, the hypothesis that changes in membrane fluidity alter function of the endocannabinoid system, as well as progression of particular neurodegenerative diseases, is described. To this end, the impact of membrane cholesterol on membrane properties and hence on neurodegenerative diseases, as well as on CB(1) signalling in vitro and on CB(1) -dependent neurotransmission within the striatum, is discussed. Overall, present evidence points to the membrane environment as a critical regulator of signal transduction triggered by CB(1) , and calls for further studies aimed at better clarifying the contribution of membrane lipids to eCBs signalling. The results of these investigations might be exploited also for the development of novel therapeutics able to combat disorders associated with abnormal activity of CB(1).

Serum total antioxidant capacity in patients with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). It is characterized by loss of myelin, the fatty tissue that surrounds and protects nerve fibres allowing them to conduct electrical impulses. Recent data indicate that oxidative stress (OS) plays a major role in the pathogenesis of multiple sclerosis (MS). The aim of this study was to estimate level of serum total antioxidative capacity in patients with multiple sclerosis. Our cross-sectional study included 33 patients with MS and 24 age and sex matched control subjects. All our patients had a Poser criteria for definite diagnostic categories of multiple sclerosis. Serum total antioxidant capacity (TAC) was measured by quantitative colorimetric determination, using Total antioxidant Capacity-QuantiCromAntioxidant Assay Kit (BioAssay systems, USA; DTAC-100). Mean serum TAC in multiple sclerosis group of patients was 119.2 mM Trolox equivalents and was significantly lower (p<0.001) compared to the control group of subjects (167.1 mM Trolox equivalents). Our results showed that oxidative stress plays an important role in pathogenesis of multiple sclerosis. This finding, also, suggests the importance of antioxidants in diet and therapy of MS patients.

Oral therapies for multiple sclerosis: a review of agents in phase III development or recently approved

Several disease-modifying therapies are approved for the management of multiple sclerosis (MS). While reasonably effective, these therapies require long-term parenteral self-injection, which is inconvenient for some patients and can be associated with injection-related adverse effects. Consequently, there is a need in MS for an oral therapy option. Currently, five oral therapies are in phase III development or have recently been approved for the treatment of relapsing-remitting MS: cladribine (approved in Russia and Australia), fingolimod (approved in the US and Russia), BG-12 (phase III), laquinimod (phase III) and teriflunomide (phase III). While the availability of oral therapies has been much anticipated by physicians and patients, neurologists will need to be cautious in selecting such therapy, which may appear to have efficacy and convenience advantages versus current therapies, but may also carry novel safety and tolerability concerns. The decision to use these new therapies will most likely be based on an overall assessment of efficacy, safety, tolerability and adherence, the potential need for monitoring and cost effectiveness. The objective of this article is to review the currently available data for each of these new oral therapies, which addresses the mechanism of action, efficacy and safety, and to provide a perspective on the potential future role of these therapies within clinical practice. Although better patient compliance is expected with the oral agents compared with the injectables, the safety profiles of these new oral drugs will have to be watched carefully.

Lipid oxidation and peroxidation in CNS health and disease: from molecular mechanisms to therapeutic opportunities

Reactive oxygen species (ROS) are produced at low levels in mammalian cells by various metabolic processes, such as oxidative phosphorylation by the mitochondrial respiratory chain, NAD(P)H oxidases, and arachidonic acid oxidative metabolism. To maintain physiological redox balance, cells have endogenous antioxidant defenses regulated at the transcriptional level by Nrf2/ARE. Oxidative stress results when ROS production exceeds the cell's ability to detoxify ROS. Overproduction of ROS damages cellular components, including lipids, leading to decline in physiological function and cell death. Reaction of ROS with lipids produces oxidized phospholipids, which give rise to 4-hydroxynonenal, 4-oxo-2-nonenal, and acrolein. The brain is susceptible to oxidative damage due to its high lipid content and oxygen consumption. Neurodegenerative diseases (AD, ALS, bipolar disorder, epilepsy, Friedreich's ataxia, HD, MS, NBIA, NPC, PD, peroxisomal disorders, schizophrenia, Wallerian degeneration, Zellweger syndrome) and CNS traumas (stroke, TBI, SCI) are problems of vast clinical importance. Free iron can react with H(2)O(2) via the Fenton reaction, a primary cause of lipid peroxidation, and may be of particular importance for these CNS injuries and disorders. Cholesterol is an important regulator of lipid organization and the precursor for neurosteroid biosynthesis. Atherosclerosis, the major risk factor for ischemic stroke, involves accumulation of oxidized LDL in the arteries, leading to foam cell formation and plaque development. This review will discuss the role of lipid oxidation/peroxidation in various CNS injuries/disorders.

Is multiple sclerosis a mitochondrial disease?

Multiple sclerosis (MS) is a relatively common and etiologically unknown disease with no cure. It is the leading cause of neurological disability in young adults, affecting over two million people worldwide. Traditionally, MS has been considered a chronic, inflammatory disorder of the central white matter in which ensuing demyelination results in physical disability. Recently, MS has become increasingly viewed as a neurodegenerative disorder in which axonal injury, neuronal loss, and atrophy of the central nervous system leads to permanent neurological and clinical disability. In this article, we discuss the latest developments on MS research, including etiology, pathology, genetic association, EAE animal models, mechanisms of neuronal injury and axonal transport, and therapeutics. In this article, we also focus on the mechanisms of mitochondrial dysfunction that are involved in MS, including mitochondrial DNA defects, and mitochondrial structural/functional changes.

Increase of uric acid and purine compounds in biological fluids of multiple sclerosis patients

OBJECTIVES

In this study, the concentrations of uric acid, purine profile and creatinine in samples of cerebrospinal fluid and serum of multiple sclerosis (MS) patients were measured by HPLC and compared with corresponding values recorded in patients without MS (cerebrospinal fluid) and healthy subjects (serum).

DESIGN AND METHODS

All samples were deproteinized with ultrafiltration (which ensures minimal sample manipulation and efficient protein removal) and then assayed for the synchronous HPLC separation of uric acid, hypoxanthine, xanthine, inosine, adenosine, guanosine and creatinine.

RESULTS

The values of all compounds assayed were significantly higher in both biological fluids of MS patients with respect to values measured in controls. In particular, serum hypoxanthine, xanthine, uric acid and sum of oxypurines were, respectively, 3.17, 3.11, 1.23 and 1.27-fold higher in these patients than corresponding values recorded in controls (p<0.001).

CONCLUSIONS

Differently from what previously reported, we here demonstrate that all purine compounds, including uric acid, are elevated in biological fluids of MS patients. Reinforced by the trend observed for creatinine, this corroborates the notion of sustained purine catabolism, possibly due to imbalance in ATP homeostasis, under these pathological conditions. These results cast doubt on the hypothesis that uric acid is depleted in MS because of increased oxidative stress, rather suggesting that this disease causes a generalized increase in purine catabolism. As observed in other pathological states, uric acid, purine compounds and creatinine, can be considered markers of metabolic energy imbalance rather than of reactive oxygen species, even in MS.

Reduction of free radicals in multiple sclerosis: effect of glatiramer acetate (Copaxone)

Free radicals have been found in high concentrations within inflammatory multiple sclerosis (MS) lesions. The superoxide anion (O(2)(-)) reacts rapidly with nitric oxide (NO), producing peroxynitrite (ONOO(-)). Glatiramer acetate (GA) is a specific MS immunomodulator that induces the synthesis of Th2 cytokines, and reduces the frequency of relapses and the formation of active brain lesions. Proinflammatory cytokines could play a role in free radicals production in the peripheral immune system as well as in the central nervous system (CNS). The effect of GA on iNOS, superoxide radicals (O(2)(-)) and 3-nitrotyrosine production by peripheral blood adherent mononuclear cells (PBAMs) was assessed. Our findings demonstrate that in vitro GA reduced spontaneous and LPS-induced iNOS, 3-nitrotyrosine, NO and O(2)(-) production, and that similar inhibition can be demonstrated ex vivo in mononuclear cells obtained from GA-treated patients. The inhibition of the production of free radicals in PBAMs may represent a new therapeutic mechanism against inflammation during MS.

Altered lipid metabolism in brain injury and disorders

Deregulated lipid metabolism may be of particular importance for CNS injuries and disorders, as this organ has the highest lipid concentration next to adipose tissue. Atherosclerosis (a risk factor for ischemic stroke) results from accumulation of LDL-derived lipids in the arterial wall. Pro-inflammatory cytokines (TNF-alpha and IL-1), secretory phospholipase A2 IIA and lipoprotein-PLA2 are implicated in vascular inflammation. These inflammatory responses promote atherosclerotic plaques, formation and release of the blood clot that can induce ischemic stroke. TNF-alpha and IL-1 alter lipid metabolism and stimulate production of eicosanoids, ceramide, and reactive oxygen species that potentiate CNS injuries and certain neurological disorders. Cholesterol is an important regulator of lipid organization and the precursor for neurosteroid biosynthesis. Low levels of neurosteroids were related to poor outcome in many brain pathologies. Apolipoprotein E is the principal cholesterol carrier protein in the brain, and the gene encoding the variant Apolipoprotein E4 is a significant risk factor for Alzheimer's disease. Parkinson's disease is to some degree caused by lipid peroxidation due to phospholipases activation. Niemann-Pick diseases A and B are due to acidic sphingomyelinase deficiency, resulting in sphingomyelin accumulation, while Niemann-Pick disease C is due to mutations in either the NPC1 or NPC2 genes, resulting in defective cholesterol transport and cholesterol accumulation. Multiple sclerosis is an autoimmune inflammatory demyelinating condition of the CNS. Inhibiting phospholipase A2 attenuated the onset and progression of experimental autoimmune encephalomyelitis. The endocannabinoid system is hypoactive in Huntington's disease. Ethyl-eicosapetaenoate showed promise in clinical trials. Amyotrophic lateral sclerosis causes loss of motorneurons. Cyclooxygenase-2 inhibition reduced spinal neurodegeneration in amyotrophic lateral sclerosis transgenic mice. Eicosapentaenoic acid supplementation provided improvement in schizophrenia patients, while the combination of (eicosapentaenoic acid + docosahexaenoic acid) provided benefit in bipolar disorders. The ketogenic diet where >90% of calories are derived from fat is an effective treatment for epilepsy. Understanding cytokine-induced changes in lipid metabolism will promote novel concepts and steer towards bench-to-bedside transition for therapies.

Role of uric acid in multiple sclerosis

In the past decade, a growing number of evidence has implicated free radicals in a variety of pathophysiological conditions including aging, cancer, and coronary heart disease. Analyses of different aspects of multiple sclerosis (MS) pathology with respect to oxidative damage have also revealed evidence of free radical injury to the central nervous system (CNS), although attempts to protect the CNS using various antioxidants have met with only moderate success. Several recent studies have reported lower levels of uric acid (UA), a major scavenger of reactive nitrogen species, in MS patients, while other studies found no such correlation. Here, we discuss these studies as well as current efforts to manipulate serum UA levels in MS patients.

Therapeutic potential and biological role of endogenous antioxidant enzymes in multiple sclerosis pathology

Reactive oxygen species contribute to the formation and persistence of multiple sclerosis (MS) lesions by acting on distinct pathological processes. To counteract the detrimental effects of ROS the central nervous system is endowed with a protective mechanism consisting of enzymatic and non-enzymatic antioxidants. Expression of most antioxidant enzymes is regulated through the transcription factor nuclear factor-E2-related factor (Nrf2) and antioxidant response elements (ARE) in the genes encoding enzymatic antioxidants and is induced by oxidative stress. In brain tissue of MS patients, enhanced expression of Nrf2/ARE-regulated antioxidants is suggestive of the occurrence of oxidative stress in these lesions. Antioxidant therapy may therefore represent an attractive treatment of MS. Several studies have shown that antioxidant therapy is beneficial in vitro and in vivo in animal models for MS. However, the use of exogenous antioxidants for MS treatment has drawbacks, as large amounts of antioxidants are required to achieve functional antioxidant levels in the central nervous system. Therefore, the induction of endogenous antioxidant enzymes by activators of the Nrf2/ARE pathway may be an interesting approach to obtain sufficient levels of antioxidants to interfere with pathological processes underlying MS lesion formation. In this review we summarize and discuss the biological role, regulation and potential therapeutic effects of endogenous antioxidant enzymes in MS. We propose that antioxidants may inhibit the development and progression of MS lesions and may therefore represent an attractive therapeutic target for the treatment of MS and other oxidative stress-related neurological diseases.

Proteomic analysis of human cerebral endothelial cells activated by multiple sclerosis serum and IFNbeta-1b

Several groups have recently described the endothelial cell (EC) as an important target of pathological mediators in multiple sclerosis (MS). Despite the recognition of the EC as a significant target in MS and a possible beneficiary of Beta-interferon therapy, the structural changes which occur in the cerebrovascular endothelium and the effects of interferon-beta 1b on these changes have not been closely evaluated. Disruption or dysregulation of the blood brain barrier (BBB) in MS represents a loss of endothelial integrity, which may facilitate the transendothelial migration of activated leukocytes responsible for the development of demyelinating lesions of MS. We used proteomics (2-dimensional gel electrophoresis and MALDI-MS) to characterize the effects of serum from MS patients with active disease (with and without interferon-beta 1b therapy) on human cerebral endothelial cells. The results of this study revealed the up- and down-regulation of expression of several proteins related to blood vessel development, cell structure, and cell cycle control. Using this approach we have identified protein 14-3-3, metavinculin, myosin-9, plasminogen, reticulocalbin-2 and-3, ribonuclease/angiogenin inhibitor 1, annexin A1, tropomyosin and Ras-related protein Rap-1A as potential new markers of active MS disease. A more complete description of cerebrovascular endothelial biomarkers and mediators in MS pathogenesis and how they are regulated by inflammatory cytokines and beta-interferons may lead to the development of more effective therapies and more accurate diagnostic markers in MS.

Role of Lipids in Brain Injury and Diseases

Lipid metabolism is of particular interest due to its high concentration in CNS. The importance of lipids in cell signaling and tissue physiology is demonstrated by many CNS disorders and injuries that involve deregulated metabolism. The long suffering lipid field is gaining reputation and respect as evidenced through the Center of Biomedical Research Excellence in Lipidomics and Pathobiology (COBRE), Lipid MAPS (Metabolites And Pathways Strategy) Consortium sponsored by NIH, European initiatives for decoding the lipids through genomic approaches, and Genomics of Lipid-associated Disorder (GOLD) project initiated by Austrian government. This review attempts to provide an overview of the lipid imbalances associated with neurological disorders (Alzheimer's, Parkinson's; Niemann-Pick; Multiple sclerosis, Huntington, amyotrophic lateral sclerosis, schizophrenia, bipolar disorders and epilepsy) and CNS injury (Stroke, traumatic brain injury; and spinal cord injury) and a few provocative thoughts. Lipidomic analyses along with RNA silencing will provide new insights into the role of lipid intermediates in cell signaling and hopefully open new avenues for prevention or treatment options.

iNOS-derived NO and nox2-derived superoxide confer tolerance to excitotoxic brain injury through peroxynitrite

Sublethal injurious stimuli induce tolerance to subsequent lethal insults, a phenomenon termed preconditioning. Inducible nitric oxide synthase (iNOS) is essential for the preconditioning induced by transient bilateral common carotid artery occlusion (BCCAO) or by systemic administration of the endotoxin lipopolysaccharide (LPS). We used a model of brain injury produced by neocortical injection of N-methyl-D-aspartate (NMDA) to investigate the mechanisms by which iNOS-derived nitric oxide (NO) contributes to tolerance induced by LPS or BCCAO. We found that the tolerance is blocked by the iNOS inhibitor aminoguanidine, is not observed in iNOS-null mice, and is rescued by the NO donor DTPA NONOate. Lipopolysaccharide failed to induce preconditioning in mice lacking the nox2 subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, suggesting that superoxide derived from NADPH oxidase is needed for the induction of the tolerance. Because superoxide reacts with NO to form peroxynitrite, we investigated the role of peroxynitrite. We found that LPS induces the peroxynitrite marker 3-nitrotyrosine in cortical neurons and that the peroxynitrite decomposition catalyst FeTPPS abolishes LPS-induced preconditioning. These results suggest that the protective effect of iNOS-derived NO is mediated by peroxynitrite formed by the reaction of NO with NADPH oxidase-derived superoxide. Thus, peroxynitrite, in addition to its well-established deleterious role in ischemic brain injury and neurodegeneration, can also be beneficial by inducing tolerance to excitotoxicity.

Effectors of demyelination and remyelination in the CNS: implications for multiple sclerosis

Most of the research on multiple sclerosis (MS) has focused on the early events that trigger demyelination and subsequent remyelination. Less attention has been given to the factors that directly mediate the demyelination that is the hallmark of the disease. Effector cells or molecules are those factors directly responsible for mediating the damage in the disease. Similarly, there are effector molecules that are critical for remyelination in the central nervous system (CNS). By understanding those effector molecules in demyelination and remyelination that directly influence the pathologic process, we should be able to generate specific therapies with the greatest potential for benefiting MS patients. This review focuses on effector cells and molecules that are critical for demyelination and remyelination in MS but also in experimental models of the disease including experimental autoimmune encephalomyelitis (EAE), virus-induced models of demyelination (Theiler's virus, murine hepatitis virus), and toxic models of demyelination (lysolecithin, ethidium bromide, and cuprizone). These are models in which the effector molecules for demyelination and remyelination have been most precisely evaluated.

Plasma lipid peroxidation and progression of disability in multiple sclerosis

Oxidative stress has been implicated in the pathophysiology of multiple sclerosis (MS), but its relation to disease progression is uncertain. To evaluate the relationship of plasma lipid peroxidation with progression of disability in MS, we measured blood plasma fluorescent lipid peroxidation products (PFLPP) levels in 23 patients with RRMS with a benign course, 32 with secondary progressive MS, 24 with primary progressive MS and 30 healthy controls. None of the patients had a relapse within the previous 3 months. Progression of disability was evaluated during a follow-up period of 5 years by the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSSS). We found plasma PFLPP levels elevated in patients with MS compared with controls (P < 0.0001), but there was no difference between patients with a benign and progressive disease course. There was no correlation between PFLPP levels and worsening of disability on the EDSS and speed of progression on the MSSS. Our data suggest that there is no relation between the degree of oxidative stress in plasma and progression of disability in MS.

Effects of lipoic acid and dihydrolipoic acid on total erythrocytic thiols under conditions of restricted glucose in vitro

The effects of lipoic acid and dihydrolipoic acid were explored on total thiol maintenance in diabetic and non-diabetic human erythrocytes in vitro over 22 hr in a 37 degrees C incubation system with no added glucose. Over 18-22.5 hr after treatment in both non-diabetic and diabetic cells, lipoic acid (1 mM) was associated with greater loss of cellular thiols than dihydrolipoic acid (1 mM), compared to respective control values. At 0.1 mM, in non-diabetic cells, although lipoic acid-treated cells' thiol levels were significantly lower than control, there was no significant difference between dihydrolipoic acid-treated cells and control cells regarding thiol levels. In addition, at 0.1 mM, dihydrolipoic acid-treated diabetic cells showed a reduction in thiol levels compared to control. At 0.01 mM, lipoic acid-treated cells had significantly lower measured thiol levels compared with diabetic cells exposed to dihydrolipoic acid, whereas in non-diabetic cells, dihydrolipoic acid-treated erythrocytic thiol levels were significantly greater than those treated with lipoic acid, although there were no other significant differences between the groups. At 22.5 hr, control values of methaemoglobin rose to 6.4 +/- 1.1% in diabetic cells and 3.6 +/- 2.1% in non-diabetic cells. Lipoic acid (1 mM) showed greater methaemoglobin formation in diabetic rather than non-diabetic cells (13.6 +/- 1.5% versus 11.6 +/- 1.5%), whereas dihydrolipoic acid-treated diabetic and non-diabetic cells were less potent in methaemoglobin generation (8.5 +/- 2.4% and 8.4 +/- 1.4%, respectively). These studies suggest that in certain circumstances such as hypoglycaemia, lipoic acid administration may actually be detrimental to cellular oxidant protection status.