ascorbic-acid and Nerve-Degeneration

Parkinson's disease (PD) is a neurodegenerative disease characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN). Oxidative stress has been identified as one of the major causes of nigrostriatal degeneration in PD. Ascorbic acid plays a role as an efficient antioxidant to protect cells from free radical damage, but it is easily oxidized and loses its antioxidant activity. To overcome this limitation, we have recently developed NXP031, a single-stranded DNA aptamer that binds to ascorbic acid with excellent specificity, reducing its oxidation and increasing its efficacy. This study investigated the neuroprotective effects of NXP031 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model. Acute degeneration of nigral dopaminergic neurons was induced by four consecutive treatments of MPTP (20 mg/kg) in male C57BL/6 J mice. NXP031 (Vitamin C/Aptamin C 200 mg/4 mg/kg) was administered intraperitoneally for 5 days following MPTP. We observed that the administration of NXP031 ameliorated MPTP-induced loss of dopaminergic neurons in the SN and exhibited improvement of MPTP-mediated motor impairment. We further found that NXP031 increased plasma ascorbic acid levels and inhibited microglia activation-induced neuroinflammation in the SN, which might contribute to the protective effects of NXP031 on nigrostriatal degeneration. Our findings suggest that NXP031 could be a potential therapeutic intervention in PD.

Topics: Animals; Ascorbic Acid; Dopaminergic Neurons; Male; Mice; Mice, Inbred C57BL; Microglia; MPTP Poisoning; Nerve Degeneration; Neuroprotective Agents; Parkinson Disease, Secondary; Postural Balance; Psychomotor Performance; Substantia Nigra

Parkinson's disease (PD) is a neurodegenerative disorder characterised by the death of dopaminergic neurons in the substantia nigra pars compacta (SNpc) region of the brain and formation of α-synuclein-containing intracellular inclusions. Excess intraneuronal iron in the SNpc increases reactive oxygen species (ROS), which identifies removing iron as a possible therapeutic strategy. Desferrioxamine B (DFOB, 1) is an iron chelator produced by bacteria. Its high Fe(iii) affinity, water solubility and low chronic toxicity is useful in removing iron accumulated in plasma from patients with transfusion-dependent blood disorders. Here, lipophilic analogues of DFOB with increased potential to cross the blood-brain barrier (BBB) have been prepared by conjugating ancillary compounds onto the amine terminus. The ancillary compounds included the antioxidants rac-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (rac-trolox, rac-TLX (a truncated vitamin E variant)), R-TLX, S-TLX, methylated derivatives of 3-(6-hydroxy-2-methylchroman-2-yl)propionic acid (α-CEHC, γ-CEHC, δ-CEHC), or 4-(5-hydroxy-3-methyl-1H-pyrazol-1-yl)benzoic acid (carboxylic acid derivative of edaravone, EDA). Compounds 2-8 could have dual function in attenuating ROS by chelating Fe(iii) and via the antioxidant ancillary group. A conjugate between DFOB and an ancillary unit without antioxidant properties (3,5-dimethyladamantane-1-carboxylic acid (AdA

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Antioxidants; Ascorbic Acid; Benzothiazoles; Blood Proteins; Deferoxamine; Disease Models, Animal; Iron; Iron Chelating Agents; Mice; Nerve Degeneration; Neurons; Parkinson Disease; Sulfonic Acids

We aimed to evaluate the protective effects of Yuk-Mi-Jihwang-Tang (YJT) against acute restraint stress-induced brain oxidative damage. A water extract of YJT was prepared and subjected to high performance liquid chromatography - diode array detector-mass spectrometry (HPLC-DAD-MS). Thirty-six heads of C57BL/6J male mice (7 weeks) were divided into six groups (n = 6/group). The mice were orally administrated YJT (0, 50, 100, or 200 mg/kg) or vitamin C (100 mg/kg) for 5 consecutive days before 6 h of acute restraint stress. In the brain tissue, lipidperoxidation, antioxidant components, and pro-inflammatory cytokines were measured, and the serum corticosterone level was determined. Acute restraint stress-induced notably increased lipid peroxidation in brain tissues, and pretreatment with YJT showed a significant decreased the lipid peroxidation levels (p< 0.05). The levels of antioxidant components including total glutathione contents, activities of SOD and catalase were remarkably depleted by acute restraint stress, whereas these alterations were significantly restored by treatment with YJT (p< 0.05 or p< 0.01). The restraint stress markedly increased pro-inflammatory cytokines, such as TNF-α and IL-6 in the gene expression and protein levels (p< 0.05 or p< 0.01). Pretreatment with YJT significantly attenuated serum corticosterone (200 mg/kg, p < 0.05). YJT drastically attenuated the levels of 4- HNE, HO-1, Nox 2 and iNOSwhich were elevated during acute restraint stress, whereas the Nrf2 level was increased in brain tissue protein levels. Our data suggest that YJT protects the brain tissue against oxidative damage and regulates stress hormones.

Topics: Animals; Antioxidants; Ascorbic Acid; Biomarkers; Brain; Brain Diseases; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Enzymes; Gene Expression Regulation, Enzymologic; Hydrocortisone; Immobilization; Inflammation Mediators; Lipid Peroxidation; Male; Mice, Inbred C57BL; Nerve Degeneration; Neuroprotective Agents; Oxidative Stress; Stress, Psychological

Endothelin-1 (ET-1) is a vasoactive peptide produced by activated astrocytes and microglia and is implicated in initiating and sustaining reactive gliosis in neurodegenerative diseases. We have previously suggested that ET-1 can play a role in the pathophysiology of amyotrophic lateral sclerosis (ALS). Indeed, we reported that this peptide is abundantly expressed in reactive astrocytes in the spinal cord of SOD1-G93A mice and ALS patients and exerts a toxic effect on motor neurons (MNs) in an in vitro model of mixed spinal cord cultures enriched with reactive astrocytes. Here, we explored the possible mechanisms underlying the toxic effect of ET-1 on cultured MNs. We show that ET-1 toxicity is not directly caused by oxidative stress or activation of cyclooxygenase-2 but requires the synthesis of nitric oxide and is mediated by a reduced activation of the phosphoinositide 3-kinase pathway. Furthermore, we observed that ET-1 is also toxic for microglia, although its effect on MNs is independent of the presence of this type of glial cells. Our study confirms that ET-1 may contribute to MN death and corroborates the view that the modulation of ET-1 signaling might be a therapeutic strategy to slow down MN degeneration in ALS.

Topics: Animals; Antioxidants; Arabidopsis Proteins; Ascorbic Acid; Cyclooxygenase 2; Embryo, Mammalian; Endothelin-1; Female; Gene Expression Regulation; Immunoprecipitation; Motor Neurons; Nerve Degeneration; Nerve Tissue Proteins; Nitric Oxide; Nuclear Proteins; Phosphatidylinositol 3-Kinases; Pregnancy; Proto-Oncogene Proteins c-akt; Rats; Rats, Wistar; Signal Transduction; Spinal Cord

Sodium vitamin C transporter 2 (SVCT2) plays a key role in transporting ascorbic acid (AA), an important intracellular antioxidant, into neurons. It is well known that ethanol (EtOH) abuse causes significant neurodegeneration, as well as endogenous AA release in certain encephalic regions. Here, we identified that SVCT2 forms part of a self-defense mechanism that protects against oxidative stress in binge drinking rats, and SVCT2 levels are correlated with antioxidants and neuronal injury. Four days of binge drinking led to massive neuron degeneration in prefrontal cortex (PFC), accompanied by increased levels of 4-hydroxynonenal (4-HNE)-adducted proteins and SVCT2 expression, as well as dramatic changes in AA levels in rat brain. AA levels were decreased in PFC and increased in cerebrospinal fluid (CSF) after binge drinking, but returned to normal on the 7th day following EtOH withdrawal. These processes were further evaluated in primary cortical neurons exposed to 100mM EtOH in vitro. Neurons transfected with SVCT2 siRNA were more susceptible than controls to certain aspects of EtOH-induced injury, including cell death, dendrite damage and increased oxidative stress. EtOH-induced up-regulation of SVCT2 was associated with activation of JNK and p38 MAPKs and the NF-κB pathway. More importantly, miRNA-125a-5p was down-regulated in PFC of 4-day binge drinking rats and negatively regulated protein expression during EtOH-induced neuronal injury. MiR-125a-5p over-expression attenuated intracellular AA levels, promoted cell death and suppressed the EtOH-induced up-regulation of p38 MAPK and SVCT2, which suggested that miR-125a-5p plays an important role in SVCT2 function in EtOH-induced neuronal injury. We speculate that SVCT2, possibly regulated by JNK/p38 MAPKs, NF-κB signaling and miR-125a-5p, has a neuroprotective effect against EtOH-induced oxidative stress. Promotion of SVCT2 expression or stimulation of SVCT2 activity may be a promising therapeutic strategy for the prevention of EtOH-associated neurodegeneration.

Topics: Aldehydes; Animals; Antioxidants; Ascorbic Acid; Binge Drinking; Dendrites; Ethanol; Gene Expression Regulation; Humans; MAP Kinase Kinase 4; MicroRNAs; Nerve Degeneration; Neurons; NF-kappa B; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Prefrontal Cortex; Rats; RNA, Small Interfering; Sodium-Coupled Vitamin C Transporters

Epilepsy is a common neurological disorder that leads to neuronal excitability and provoke various forms of cellular reorganization in the brain. In this study, we investigate the anti-convulsant and neuroprotective effects of thymoquinone (TQ) and vitamin C against pentylenetetrazole (PTZ)-induced generalized seizures. Epileptic seizures were induced in adult rats using systemic intraperitoneal injections of PTZ (50 mg/kg) for 7 days. Animals pretreated with either TQ or vitamin C or in combination attenuated PTZ-induced seizures and mortality in rats as well neurodegeneration in the cells. Compared to PTZ, TQ and vitamin C significantly prolonged the onset of seizures (p > 0.05) as well decrease the high-grade seizures. Analysis of electroencephalogram (EEG) recordings revealed that TQ or vitamin C supplementation significantly reduced polyspike and epileptiform discharges. Epileptic seizures caused a decline in expression of gamma-aminobutyric acid B1 receptor (GABAB1R) (p > 0.05), unchanged expression of protein kinase A (PKA), decreased calcium/calmodulin-dependent protein kinase II (CaMKII) (p > 0.05) and inhibit the phosphorylation of cAMP response element-binding protein (CREB) (p > 0.05) in cortex and hippocampus, respectively, compared with control. Changes in expression of GABAB1R, CaMKII and CREB by PTZ were reversed by TQ and vitamin C supplementation. Moreover, PTZ significantly increased Bax, decreased Bcl-2 expression and finally the activation of caspase-3. TQ and vitamin C pretreatment reversed all these deleterious effects induced by PTZ. TQ and vitamin C showed anticonvulsant effects via activation of GABAB1R/CaMKII/CREB pathway and suggest a potential therapeutic role in epilepsy.

Topics: Animals; Anticonvulsants; Antioxidants; Ascorbic Acid; Benzoquinones; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Caspase 3; Cerebral Cortex; Convulsants; Cyclic AMP Response Element-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Electroencephalography; Enzyme Activation; Enzyme Induction; GABA-A Receptor Antagonists; GABA-B Receptor Agonists; Hippocampus; Nerve Degeneration; Nerve Tissue Proteins; Neuroprotective Agents; Pentylenetetrazole; Rats; Rats, Sprague-Dawley; Receptors, GABA-B; Seizures; Signal Transduction; Up-Regulation

Several data suggest that excitotoxicity due to excessive glutamatergic neurotransmission may be an important factor in the mechanisms of motor neuron (MN) death occurring in amyotrophic lateral sclerosis (ALS). We have previously shown that the overactivation of the Ca(2+)-permeable α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) glutamate receptor type, through the continuous infusion of AMPA in the lumbar spinal cord of adult rats during several days, results in progressive rear limb paralysis and bilateral MN degeneration. Because it has been shown that energy failure and oxidative stress are involved in MN degeneration, in both ALS and experimental models of spinal MN degeneration, including excitotoxicity, in this work we tested the protective effect of the energy substrates pyruvate and β-hydroxybutyrate (βHB) and the antioxidants glutathione ethyl ester (GEE) and ascorbate in this chronic AMPA-induced neurodegeneration.. AMPA infusion induced remarkable progressive motor deficits, assessed by two motor tasks, that by day seven reach bilateral rear limb paralysis. These effects correlate with the death of >80% of lumbar spinal MNs in the infused and the neighbor spinal cord segments, as well as with notable astrogliosis in the ventral horns, detected by glial fibrillary acidic protein immunohistochemistry. Co-infusion with pyruvate or βHB notably prevented the motor deficits and paralysis, decreased MN loss to <25% and completely prevented the induction of astrogliosis. In contrast, the antioxidants tested were ineffective regarding all parameters analyzed.. Chronic progressive excitotoxicity due to AMPA receptors overactivation results in MN death and astrogliosis, with consequent motor deficits and paralysis. Because of the notable protection against these effects exerted by pyruvate and βHB, which are well established mitochondrial energy substrates, we conclude that deficits in mitochondrial energy metabolism are an important factor in the mechanisms of this slowly developed excitotoxic MN death, while the lack of protective effect of the antioxidants indicates that oxidative stress seems to be less significant factor. Because excitotoxicity may be involved in MN degeneration in ALS, these findings suggest possible preventive or therapeutic strategies for the disease.

Topics: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Antioxidants; Ascorbic Acid; Cell Death; Disease Models, Animal; Extremities; Gliosis; Glutathione; Hydroxybutyrates; Male; Mitochondria; Motor Activity; Motor Neurons; Nerve Degeneration; Neuroprotection; Oxidative Stress; Paralysis; Pyruvic Acid; Rats; Rats, Wistar; Receptors, AMPA; Spinal Cord; Treatment Outcome

Exposure to alcohol during brain development may cause a neurological syndrome called fetal alcohol syndrome, characterized by pre- and postnatal growth deficiencies, craniofacial anomalies, and evidence of CNS dysfunction. The objective of this study was to evaluate pentylenetetrazol (PTZ) and ethanol effects on Bax, Bcl-2 expression, which further induced activation of caspase-3, release of cytochrome-c from mitochondria, and to observe the protective effects of vitamin C (vit-C) against PTZ and ethanol-induced apoptotic neurodegeneration in primary-cultured neuronal cells at gestational day 17.5. Apoptotic neurodegeneration and neuroprotective effect of vit-C were measured by using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay, Western blot analysis, which further conformed by the measurement of mitochondrial membrane potential using JC-1 detection kit and immunofluorescence analysis. The results showed that PTZ and ethanol produced extensive Bax-dependent caspase-9 and caspase-3 activation and caused neuronal apoptosis. Furthermore, the cotreatment of vit-C along with ethanol and PTZ showed significantly decreased expression of Bax, caspase-9, caspase-3, cytochrome-c, and significantly increased expression of antiapoptotic Bcl-2 protein when compared with control group. Our findings indicate that PTZ and ethanol activate an intrinsic apoptotic death program in neurons that is likely to contribute to the neuropathologic effects in fetal alcohol exposure, and vit-C can prevent some of the deleterious effects of PTZ and ethanol on the developing brain. The available experimental evidence and the safety of vit-C in pregnancy suggest the experimental use of ascorbic acid as a new and effective protective agent ethanol and PTZ-induced apoptotic neurodegeneration.

Topics: Animals; Apoptosis; Ascorbic Acid; Blotting, Western; Cells, Cultured; Central Nervous System Depressants; Ethanol; Female; Fetal Alcohol Spectrum Disorders; Fluorescent Antibody Technique; GABA Antagonists; Hippocampus; Nerve Degeneration; Neurons; Pentylenetetrazole; Pregnancy; Rats; Rats, Sprague-Dawley; Vitamins

The present study was designed to observe the effect of PTZ on expression of caspsae-3, and to evaluate the neuroprotective role of vitamin C (vit-C) against PTZ-induced apoptotic neurodegeneration in adult rat brain. We observed that administration of a single conclusive dose of pentylenetetrazol (PTZ 50mg/kg) in adults rats induced epileptic seizure and increased activation of caspase-3 and caused neuronal death. Further, rats were injected with vit-C (250 mg/kg) 30 min before PTZ injection. The protective effect of vit-C against PTZ-induced apoptotic neurodegeneration in adult rat brain was observed using Western blot analysis and Nissl staining. The results showed that conclusive dose of PTZ-induced seizure, increased expression of caspase-3 and neuronal apoptosis in adult rat brain. Whereas, the pretreatment of vit-C along with PTZ showed significantly decreased expression of caspase-3 as compare to control group. Finally, our results indicated that vit-C can prevent some of the deleterious effect of seizure and neuronal degeneration induced by PTZ in adult rat brain.

Topics: Animals; Apoptosis; Ascorbic Acid; Brain; Caspase 3; Disease Models, Animal; Epilepsy; Male; Nerve Degeneration; Neuroprotective Agents; Pentylenetetrazole; Rats; Rats, Sprague-Dawley

The pathogenesis of rapid eye movement (REM) sleep behavior disorder (RBD) is not clear despite its frequent association with Parkinson's disease (PD). We investigated whether the nigrostriatal dopaminergic system is involved in the development of idiopathic RBD.. Fourteen patients with RBD, 14 patients with PD and 12 normal controls were included in the study. The diagnosis of RBD was confirmed on polysomnography. All the participants performed single-photon emission computed tomography imaging 3 h after injection of [(123)I]FP-CIT. During REM sleep of the RBD patients, each 30-s epoch was rated as 'tonic' when there was at least 50% of tonically maintained chin electromyography (EMG) activity in the epoch. Phasic EMG activities were calculated as the percentage of 3-s mini-epoch containing phasic EMG events (leg and chin, separately).. The RBD patients showed a trend of lower binding in the striatum than the normal controls (P = 0.07), and the significance was revealed in the putamen (P = 0.02). However, in 11 individual cases of the 14 RBD patients, the dopamine transporter (DAT) densities in the putamen still remained within the normal range. In the RBD patients, there was no correlation between EMG activities and DAT densities.. Nigrostriatal dopaminergic degeneration could be a part of the pathogenesis of RBD, but not essential for the development of RBD. The lack of correlation between RBD severity and DAT densities suggests that another pathogenic process not related to nigrostriatal dopaminergic transmission may be implicated in RBD.

Topics: Aged; Ascorbic Acid; Caudate Nucleus; Chin; Cholecalciferol; Corpus Striatum; Dehydroepiandrosterone; Dopamine; Dopamine Plasma Membrane Transport Proteins; Electromyography; Facial Muscles; Female; Humans; Male; Middle Aged; Nerve Degeneration; Nicotinic Acids; Plant Extracts; Polysomnography; Putamen; REM Sleep Behavior Disorder; Tomography, Emission-Computed, Single-Photon; Tropanes

Cyclooxygenase-2 (COX-2) activity has been implicated in the pathogenesis of ischemic injury, but the exact mechanisms responsible for its toxicity remain unclear. Infection of primary neurons with an adenovirus expressing wild type (WT) COX-2 increased the susceptibility of neurons to hypoxia. Infection with an adenoviral vector expressing COX-2 with a mutation at the cyclooxygenase site did not increase susceptibility to hypoxia, whereas over-expression of COX-2 with a mutation in the peroxidase site produced similar susceptibility to hypoxia as WT COX-2. Primary neuronal cultures obtained from transgenic mice bearing a mutation in the COX-2 cylooxygenase site were protected from hypoxia. Mice with a mutation in the cyclooxygenase site had smaller infarctions 24 h after 70 min of middle cerebral artery occlusion than WT control mice. COX-2 activity had no effect on the formation of protein carbonyls. Ascorbate radicals were detected by electron paramagnetic resonance as a product of recombinant COX-2 activity and were blocked by COX-2 inhibitors. Similarly, formation of ascorbate radicals was inhibited in the presence of COX-2 inhibitors and in homogenates obtained from COX-2 null mice. Taken together, these results indicate that the cyclooxygenase activity of COX-2 is necessary to exacerbate neuronal hypoxia/ischemia injury rather than the peroxidase activity of the enzyme.

Topics: Animals; Arachidonic Acid; Ascorbic Acid; Brain Infarction; Catalytic Domain; Cell Line; Cells, Cultured; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Free Radicals; Humans; Hypoxia-Ischemia, Brain; Mice; Mice, Transgenic; Nerve Degeneration; Oxidative Stress; Peroxidase; Prostaglandin H2; Rats

Both the neurotransmitter dopamine (DA) and a neurotoxic metabolite, 6-hydroxy DA, can be oxidized to generate hydrogen peroxide and other reactive species (ROS). ROS promote oxidative stress and have been implicated in dopaminergic neurodegeneration, e.g., Parkinson's disease (PD). There is also evidence for a relation between catecholamine-mediated oxidative damage in dopaminergic neurons and the effects of these neurotransmitters on the redox state of cytochrome c (Cytc). In neurons and other cells, oxidative stress may be enhanced by abnormal release of Cytc and other mitochondrial proteins into the cytoplasm. Cytc release can result in apoptosis; but sub-apoptogenic-threshold release can also occur, and may be highly damaging in the presence of DA metabolites. Loss of mitochondrial membrane integrity, a pathological situation of relevance to several aging-related neurodegenerative disorders including PD, contributes to release of Cytc; and the level of such release is known to be indicative of the extent of mitochondrial dysfunction. In this context, we have used a Cytc-enhanced 6-hydroxy DA oxidation reaction to gauge dietary antioxidant activities. Anthocyanin-rich preparations of Vaccinium species (Vaccinium myrtillus, Vaccinium corymbosum, and Vaccinium oxycoccus) as well as a purified glycosylated anthocyanidin were compared. The most potent inhibition of oxidation was observed with V. myrtillus preparation: 50% inhibition with 7 microM of total anthocyanins. This activity was 1.5-4 times higher than that for the other preparations or for the purified anthocyanin. Ascorbate (Vitamin C), at up to 4-fold higher concentrations, did not result in significant inhibition in this assay. Antioxidant activity in the assay correlated strongly (r2>0.91, P<0.01) with reported Vaccinium content of anthocyanins and total cyanidins, but not quercetin or myricetin. The results provide evidence for the high potency of anthocyanins towards a potentially neurotoxic reaction, and provide a basis for in vivo testing of these flavonoids and their physiological metabolites in the context of neuro- and mitochondrio-protective effects.

Topics: Animals; Anthocyanins; Antioxidants; Ascorbic Acid; Cytochromes c; Dopamine; Flavonoids; Glucosides; Kinetics; Mitochondria; Nerve Degeneration; Neurotoxicity Syndromes; Oxidation-Reduction; Oxidopamine; Sympatholytics; Vaccinium

Man, with other primates, lost the ability to synthesize vitamin C through an inactivating mutation of the gene encoding gulonolactone oxidase (GULO) millions of years ago. Though the consequences of this prehistoric loss must have been favorable (and thus selected for) at the population level, the inability to produce vitamin C may have serious health implications for modern humans, especially for those conditions in which antioxidants (like vitamin C) have been implicated as potential therapeutic agents. Two general types of recent findings regarding vitamin C have made re-evaluation of this important nutrient imperative. First, vitamin C is now known to be involved in several novel physiological phenomena including stem cell differentiation and respiratory development, which likely require pharmacological levels of vitamin C. Secondly, the growing recognition that many ageing-related diseases, including heart disease, neural degeneration and cancer, may have a contributing oxidative damage factor that might be reduced by dietary antioxidants such as vitamin C. In this paper, we hypothesize that high serum-level vitamin C provides important, broad-ranging therapeutic benefits in treating ageing-related degenerative diseases. This hypothesis can be readily tested using traditional and newly-developed genetically-engineered animal models.

Topics: Aging; Antioxidants; Ascorbic Acid; Cardiovascular Diseases; Humans; Models, Biological; Neoplasms; Nerve Degeneration

Free radical formation in the cochlea plays a key role in the development of noise-induced hearing loss (NIHL). The amount, distribution, and time course of free radical formation have been defined, including a clinically significant formation of both reactive oxygen species and reactive nitrogen species 7-10 days after noise exposure. Reduction in cochlear blood flow as a result of free radical formation has also been described. Here we report that the antioxidant agents vitamins A, C, and E act in synergy with magnesium to effectively prevent noise-induced trauma. Neither the antioxidant agents nor the magnesium reliably reduced NIHL or sensory cell death with the doses we used when these agents were delivered alone. In combination, however, they were highly effective in reducing both hearing loss and cell death even with treatment initiated just 1 h before noise exposure. This study supports roles for both free radical formation and noise-induced vasoconstriction in the onset and progression of NIHL. Identification of this safe and effective antioxidant intervention that attenuates NIHL provides a compelling rationale for human trials in which free radical scavengers are used to eliminate this single major cause of acquired hearing loss.

Topics: Animals; Ascorbic Acid; Free Radical Scavengers; Guinea Pigs; Magnesium; Male; Nerve Degeneration; Noise; Organ of Corti; Vitamin A; Vitamin E

Glutathione (GSH) metabolism dysfunction is one risk factor in schizophrenia. A transitory brain GSH deficit was induced in Wistar (WIS) and mutant (ODS; lacking ascorbic acid synthesis) rats using BSO (l-buthionine-(S,R)-sulfoximine) from post-natal days 5-16. When GSH was re-established to physiological levels, juvenile BSO-ODS rats were impaired in the water maze task. Long after treatment cessation, adult BSO-WIS/-ODS rats showed impaired place discrimination in the homing board with distributed visual or olfactory cues. Their accuracy was restored when a single cue marked the trained position. Similarly, more working memory errors were made by adult BSO-WIS in the radial maze when several olfactory cues were present. These results reveal that BSO rats did not suffer simple sensory impairment. They were selectively impaired in spatial memory when the task required the integration of multimodal or olfactory cues. These results, in part, resemble some of the reported olfactory discrimination and cognitive impairment in schizophrenia.

Topics: Aging; Animals; Animals, Newborn; Ascorbic Acid; Brain; Cognition Disorders; Cues; Disease Models, Animal; Female; Glutathione; Male; Maze Learning; Memory Disorders; Nerve Degeneration; Olfaction Disorders; Orientation; Oxidative Stress; Rats; Rats, Mutant Strains; Rats, Wistar; Schizophrenia; Sex Characteristics; Smell

Lead is a neurotoxin that affects the developing central nervous system and may potentially induce apoptotic cell death. We investigated the effect of ascorbic acid against lead-induced neurotoxicity in the developing rat hippocampus. Female Sprague-Dawley rats were divided into three groups: control group, lead-treated group and lead plus ascorbic acid-treated group. Lead (0.2% lead acetate) was administered to female rats during pregnancy and lactation, in their drinking water. During this period, rats in the lead plus ascorbic acid-treated group received 100 mg/kg/day ascorbic acid, orally. At the end of the treatment, neuronal damage, apoptosis and blood lead levels were determined and the levels of Bax and Bcl-2 were immunodetected in the hippocampus of 21-day-old male pups. Histopathological evaluation demonstrated that ascorbic acid significantly attenuates apoptosis in the developing hippocampus and also spares hippocampal CA1, CA3 and dentate gyrus (DG) neurons. Simultaneous administration of ascorbic acid and lead lowered the level of Bax protein and increased Bcl-2 in pup hippocampus and reduced lead level in blood of dams compared with lead-treated only. Based on these results, it seems that ascorbic acid may potentially be beneficial in treating lead-induced brain injury in the developing rat brain.

Topics: Animals; Animals, Newborn; Apoptosis; Ascorbic Acid; bcl-2-Associated X Protein; Disease Models, Animal; Drug Interactions; Female; Gene Expression Regulation, Developmental; Hippocampus; In Situ Nick-End Labeling; Lead; Lead Poisoning; Male; Nerve Degeneration; Neuroprotective Agents; Pregnancy; Proto-Oncogene Proteins c-bcl-2; Rats

Urate and ascorbate play a major role in the defense mechanism of the brain against oxidative damage induced by traumatic brain injury. The severity and extent of brain damage are known to increase with age. This may be due to different basal levels of endogenous antioxidants, and/or to impaired ability of the old brain to recruit and elevate the levels of antioxidants following injury. To investigate this hypothesis, we measured basal ascorbate and urate levels in the hippocampus, using microdialysis in young, adults and old rats, and performed closed head injury (CHI) in young (5-6 weeks) and old rats (19-20 months). Basal ascorbate, but not urate levels in old rats were significantly lower than in the adults. The ability of the old rats to increase ascorbate levels after CHI was significantly lower than that of the young ones, as indicated by lower levels of ascorbate and urate in the dialysate of old rats. This lower level of antioxidant mobilization in the old brain may explain the extended damage found in histology. Evaluation of hippocampal cell loss (p<0.05) and axonal degeneration in the corpus callosum showed more extensive damage in old as compared to young rats (chi(2)=4.25; p<0.05). These findings shed more light on the susceptibility of old rat brain to CHI-induced oxidative damage.

Topics: Aging; Animals; Antioxidants; Ascorbic Acid; Axons; Brain Injuries; Corpus Callosum; Extracellular Matrix; Hippocampus; Male; Microdialysis; Nerve Degeneration; Neurons; Oxidative Stress; Rats; Rats, Wistar; Uric Acid

Alzheimer's disease is characterized by extracellular beta-amyloid plaques, intraneuronal Tau-inclusions and cell death of cholinergic neurons. Recent evidence indicates that the vascular system may play an important role in the development of this progressive neurodegenerative disease. The aim of this study was to observe, if brain capillary endothelial cells (BCEC) may produce and secrete factors which induce cell death of cholinergic neurons, and if this effect is counteracted by (1) NGF, MK-801 or vitamin C, (2) modulated by experimentally-induced inflammation with interleukin-1beta and lipopolysaccharide (IL-1beta and LPS) or (3) by blocking of different intracellular signalling pathways. Cholinergic neurons were cultivated in organotypic brain slices of the nucleus basalis of Meynert and treated with conditioned medium derived from BCEC, supplemented with different protective factors. BCEC were stimulated with IL-1beta and LPS or different intracellular pathway inhibitors before collection of conditioned medium. Cholinergic neurons were detected by immunohistochemistry for choline-acetyltransferase. Possible effects on BCEC viability and proliferation were determined by nuclear staining, BrdU incorporation and release of nitrite and lactate-dehydrogenase. BCEC released factors that can kill cholinergic neurons. This neurotoxic effect was blocked by NGF and MK-801 (a NMDA-antagonist), but not by vitamin C. Pretreatment of BCEC with intracellular pathway inhibitors did not change the neurotoxicity, but pretreatment with IL-1beta and LPS abolished the neurotoxic effect. In summary, BCEC produce and secrete molecules which induce excitotoxic cell death of cholinergic neurons. It is concluded that excitotoxic factors secreted by vascular cells may contribute to the development of cholinergic neurodegeneration as it occurs in Alzheimer's disease.

Topics: Alzheimer Disease; Animals; Antioxidants; Ascorbic Acid; Brain; Cell Death; Cells, Cultured; Cholinergic Fibers; Culture Media, Conditioned; Dizocilpine Maleate; Endothelial Cells; Inflammation; Interleukin-1beta; Lipopolysaccharides; Nerve Degeneration; Nerve Growth Factor; Neuroprotective Agents; Rats; Rats, Sprague-Dawley

Oxidative damage has been implicated in the pathogenesis of cerebral ischemia. We previously demonstrated that exogenously supplied dehydroascorbic acid (DHA), an oxidized, blood-brain barrier transportable form of the antioxidant ascorbic acid (AA), improves outcome after experimental stroke.. To investigate the neuroprotective effect of DHA therapy, we measured cerebral AA levels using a novel assay, quantified markers of lipid peroxidation, and evaluated infarct volume after reperfused stroke in a murine model. All experiments were performed using a new citrate/sorbitol-stabilized DHA formulation to improve the stability of the compound.. Intraparenchymal AA levels declined after cerebral ischemia/reperfusion and were repleted in a dose-dependent fashion by postischemic administration of intravenous DHA (P < 0.01). Repletion of these levels was associated with reductions in cerebral malondialdehyde levels (P < 0.05), which were also elevated after reperfused stroke. DHA repletion of interstitial AA levels and reduction in cerebral lipid peroxidation was associated with dose-dependent reductions in infarct volume (P < 0.05).. Together, these results indicate that an intravenous cerebroprotective dose of citrate/sorbitol-stabilized DHA is correlated with increased brain ascorbate levels and a suppression of excessive oxidative metabolism.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Cerebral Infarction; Citric Acid; Dehydroascorbic Acid; Disease Models, Animal; Excipients; Infarction, Middle Cerebral Artery; Injections, Intravenous; Lipid Peroxidation; Mice; Mice, Inbred C57BL; Nerve Degeneration; Neuroprotective Agents; Oxidative Stress; Reperfusion Injury; Sorbitol; Treatment Outcome; Up-Regulation

The specific role of endogenous glutathione in response to neuronal degeneration induced by trimethyltin (TMT) in the hippocampus was examined in rats. A single injection of TMT (8 mg/kg, i.p.) produced a rapid increase in the formation of hydroxyl radical and in the levels of malondialdehyde (MDA) and protein carbonyl. TMT-induced seizure activity significantly increased after this initial oxidative stress, and remained elevated for up to 2 weeks post-TMT. Although a significant loss of hippocampal Cornus Ammonis CA1, CA3 and CA4 neurons was observed at 3 weeks post-TMT, the elevation in the level of hydroxyl radicals, MDA, and protein carbonyl had returned to near-control levels at that time. In contrast, the ratio of reduced to oxidized glutathione remained significantly decreased at 3 weeks post-TMT, and the glutathione-like immunoreactivity of the pyramidal neurons was decreased. However glutathione-positive glia-like cells proliferated mainly in the CA1, CA3, and CA4 sectors and were intensely immunoreactive. Double labeling demonstrated the co-localization of glutathione-immunoreactive glia-like cells and reactive astrocytes, as indicated by immunostaining for glial fibrillary acidic protein. This suggests that astroglial cells were mobilized to synthesize glutathione in response to the TMT insult. The TMT-induced changes in glutathione-like immunoreactivity appear to be concurrent with changes in the expression levels of glutathione peroxidase and glutathione reductase. Ascorbate treatment significantly attenuated TMT-induced seizures, as well as the initial oxidative stress, impaired glutathione homeostasis, and neuronal degeneration in a dose-dependent manner. These results suggest that ascorbate is an effective neuroprotectant against TMT. The initial oxidative burden induced by TMT may be a causal factor in the generation of seizures, prolonged disturbance of endogenous glutathione homeostasis, and consequent neuronal degeneration.

Topics: Animals; Antioxidants; Ascorbic Acid; Astrocytes; Dose-Response Relationship, Drug; Drug Interactions; Epilepsy; Glial Fibrillary Acidic Protein; Glutathione; Glutathione Disulfide; Hippocampus; Homeostasis; Hydroxyl Radical; Malondialdehyde; Nerve Degeneration; Neurons; Oxidative Stress; Rats; Rats, Sprague-Dawley; Trimethyltin Compounds

The results of several in vitro studies have shown that cysteine prodrugs, particularly N-acetylcysteine, are effective antioxidants that increase the survival of dopaminergic neurons. N-acetylcysteine can be systemically administered to deliver cysteine to the brain and is of potential use for providing neuroprotection in the treatment of Parkinson's disease. However, it has also been reported that an excess of cysteine may induce neurotoxicity. In the present study, we injected adult rats intrastriatally with 2.5 microl of 6-hydroxydopamine (7.5 microg) and N-acetylcysteine (240 mM) or cysteine (240 mM) or intraventricularly with 6-hydroxydopamine (200 microg) and subcutaneously with N-acetylcysteine (10 and 100 mg/kg). We studied the effects of these compounds on both the nigrostriatal dopaminergic terminals and the surrounding striatal tissue. The tissue was stained with fluoro-jade (a marker of neuronal degeneration) and processed by immunohistochemistry to detect tyrosine hydroxylase, neuronal and glial markers, and the stress protein heme-oxygenase-1. After intrastriatal injection, both cysteine and N-acetylcysteine had clear neuroprotective effects on the striatal dopaminergic terminals, but also led to neuronal degeneration (as revealed by fluoro-jade staining) and astroglial and microglial activation, as well as intense induction of heme-oxygenase-1 in astrocytes and microglial cells. Subcutaneous administration of N-acetylcysteine also induced significant reduction of the dopaminergic lesion (about 30% reduction). However, we did not observe appreciable N-acetylcysteine-induced fluoro-jade labeling in striatal neurons or any of the above-mentioned changes in striatal glial cells. The results suggest that low doses of cysteine prodrugs may be useful neuroprotectors in the treatment of Parkinson's disease.

Topics: Acetylcysteine; Animals; Antigens, CD; Antigens, Neoplasm; Antigens, Surface; Ascorbic Acid; Avian Proteins; Basigin; Blood Proteins; Cell Count; Corpus Striatum; Cysteine; Dopamine; Drug Administration Routes; Female; Fluoresceins; Fluorescent Dyes; Free Radical Scavengers; Glial Fibrillary Acidic Protein; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Hydroxydopamines; Immunohistochemistry; Membrane Glycoproteins; Nerve Degeneration; Neurons; Organic Chemicals; Phosphopyruvate Hydratase; Rats; Rats, Sprague-Dawley; Tyrosine 3-Monooxygenase

Clinical trials of several neurodegenerative diseases have increasingly targeted the evaluation of various antioxidants' effectiveness. The human diet contains several thousand phytochemicals, many of which have significant bioactivities. Vitamin C, a naturally occurring antioxidant, is known to reduce the risk of neurodegenerative disorders such as Alzheimer's disease. Quercetin, one of the major flavonoids in some fruits and vegetables, has much stronger antioxidative and anticarcinogenic activities than vitamin C. Therefore, we investigated the protective effects of quercetin on hydroxy peroxide-induced neurodegeneration. To determine the protective effects, PC12 cells were preincubated with quercetin and vitamin C before H(2)O(2) treatment for 2 h. Results showed that cell viability was clearly improved with quercetin, and quercetin showed a higher protective effect than vitamin C. Because oxidative stress is known to increase neuronal cell membrane breakdown, we further investigated lactate dehydrogenase and trypan blue exclusion assays. We observed that quercetin decreased oxidative stress-induced neuronal cell membrane damage more than vitamin C. These results suggest that quercetin, in addition to many other biological benefits, contributes significantly to the protective effects of neuronal cells from oxidative stress-induced neurotoxicity, such as Alzheimer disease.

Topics: Animals; Antioxidants; Ascorbic Acid; Cell Membrane; Cell Survival; Hydrogen Peroxide; Nerve Degeneration; Neurons; Oxidative Stress; PC12 Cells; Quercetin; Rats

Previous studies have shown that acute systemic administration of ethanol induced ascorbic acid release in the striatum. However, the pharmacological implications of ethanol-induced striatal ascorbic acid release are unclear. In the present study, ethanol-induced extracellular changes of ascorbic acid and hydroxyl radical levels were detected in rat striatum by using brain microdialysis coupled to high-performance liquid chromatography with electrochemical detection. It was found that both in male and female rats, ethanol (3.0 g/kg, i.p.) increased striatal ascorbic acid release in the first 60 min after ethanol administration. Meanwhile, the extracellular hydroxyl radical levels, detected as 2,3- and 2,5-DHBA, were significantly decreased. However, when the ascorbic acid levels returned to the baseline, hydroxyl radical levels rebounded. Administration of DL-fenfluramine (20 mg/kg, i.p.) had no effect on the basal levels of ascorbic acid and hydroxyl radical, but significantly blocked ethanol-induced ascorbic acid release and increased hydroxyl radical levels significantly. Exogenous administration of ascorbic acid (20 mg/kg, s.c.) increased the extracellular levels of ascorbic acid in the striatum, and inhibited the increase of 2,3- and 2,5-DHBA in DL-fenfluramine plus ethanol group. These results provide first evidence that release of endogenous ascorbic acid in the striatum plays an important role in preventing oxidative stress by trapping hydroxyl radical in the central nervous system.

Topics: Alcohol-Induced Disorders, Nervous System; Animals; Ascorbic Acid; Drug Interactions; Ethanol; Extracellular Space; Female; Fenfluramine; Hydroxybenzoates; Hydroxyl Radical; Male; Microdialysis; Neostriatum; Nerve Degeneration; Neurons; Oxidative Stress; Rats; Selective Serotonin Reuptake Inhibitors; Sex Characteristics

Of particular physiological interest, ascorbate, the ionized form of ascorbic acid, possesses strong reducing properties. However, it has been shown to induce oxidative stress and lead to apoptosis under certain experimental conditions. Ascorbate in the brain is released during hypoxia, including stroke, and is subsequently oxidized in plasma. The oxidized product (dehydroascorbate) is transported into neurons via a glucose transporter (GLUT) during a reperfusion period. The dehydroascorbate taken up by cells is reduced to ascorbate by both enzymatic and non-enzymatic processes, and the ascorbate is stored in cells. This reduction process causes an oxidative stress, due to coupling of redox reactions, which can induce cellular damage and trigger apoptosis. Ascorbate treatment decreased cellular glutathione (GSH) content, and increased the rates of lipid peroxide production in rat cortical slices. Wortmannin, a specific inhibitor of phosphatidylinositol (PI)-3-kinase (a key enzyme in GLUT translocation), prevented the ascorbate induced-decrease of GSH content, and suppressed ascorbate-induced lipid peroxide production. However, wortmannin was ineffective in reducing hydrogen peroxide (H(2)O(2))-induced oxidative stress. The oxidative stress caused ceramide accumulation, which was proportionally changed with lipid peroxides when the cortical slices were treated with ascorbate. These differential effects support the hypothesis that GLUT efficiently transports the dehydroascorbate into neurons, causing oxidative stress.

Topics: Androstadienes; Animals; Apoptosis; Ascorbic Acid; Brain; Ceramides; Dehydroascorbic Acid; Dose-Response Relationship, Drug; Enzyme Inhibitors; Glutathione; Hypoxia-Ischemia, Brain; Lipid Peroxides; Male; Monosaccharide Transport Proteins; Nerve Degeneration; Organ Culture Techniques; Oxidative Stress; Rats; Rats, Sprague-Dawley; Rotenone; Signal Transduction; Sphingomyelins; Stroke; Uncoupling Agents; Wortmannin

to evaluate the effectiveness of an intraaortic delivered solution on preventing spinal cord injury.. forty rabbits were allocated into five equal groups.. one clamp was placed just distal to the left renal artery, and another was placed just above the iliac bifurcation for 40 min. Group 1 was not infused (control group). Through a 24G vascular catheter inserted into the isolated aortic segment, 20 ml of LR solution at room temperature (Group 2) 20 ml of LR solution at 3 degrees C (Group 3), and 20 ml of LR solution at 3 degrees C containing 30 mg/kg of methylprednisolone (Group 4) were infused over 3 min. In Group 5, 10 mg/kg of vitamins E and C were delivered two days before the experiment, and 20 ml of LR solution at 3 degrees C containing 30 mg/kg of methylprednisolone, and 10 mg/kg of vitamins E and C was infused at the operation. Postoperative spinal cord function was assessed using Tarlov's criteria.. the neurologic status of Groups 3, 4, and 5 was significantly superior to that of Groups 1 and 2. No paraplegia was observed in Groups 4 and 5. Spastic paraplegia occurred in all rabbits of Groups 1 and 2, and in 20% of Group 3. In the electron microscopic evaluation of spinal cord specimens, normal histologic structure was observed in Groups 4 and 5, whereas, some derangements were observed in all others.. intraaortic infusion of a hypothermic blended solution containing methylprednisolone, vitamins C and E provided best protection against postischaemic spinal cord dysfunction.

Topics: Animals; Aorta, Abdominal; Ascorbic Acid; Drug Therapy, Combination; Hypothermia, Induced; Infusions, Intra-Arterial; Isotonic Solutions; Methylprednisolone; Nerve Degeneration; Paraplegia; Rabbits; Ringer's Lactate; Spinal Cord; Spinal Cord Ischemia; Vitamin E

EPC-K1, L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl-hydrogen phosphate] potassium salt, is a novel antioxidant. In this study, we investigated a reduction of oxidative neuronal cell damage with EPC-K1 by immunohistochemical analysis for 8-hydroxy-2'-deoxyguanosine (8-OHdG) in rat brain with 60 min transient middle cerebral artery occlusion, in association with terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) and staining for total and active caspase-3. Treatment with EPC-K1 (20 mg kg(-1) i.v.) significantly reduced infarct size (p < 0.05) at 24 h of reperfusion. There were no positive cells for 8-OHdG and TUNEL in sham-operated brain, but numerous cells became positive for 8-OHdG, TUNEL and caspase-3 in the brains with ischemia. The number was markedly reduced in the EPC-K1 treated group. These reductions were particularly evident in the border zone of the infarct area, but the degree of reduction was less in caspase-3 staining than in 8-OHdG and TUNEL stainings. These results indicate EPC-K1 attenuates oxidative neuronal cell damage and prevents neuronal cell death.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Brain; Brain Infarction; Brain Ischemia; Caspase 3; Caspases; Deoxyguanosine; DNA Damage; Free Radicals; Immunohistochemistry; In Situ Nick-End Labeling; Infarction, Middle Cerebral Artery; Male; Nerve Degeneration; Neurons; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Vitamin E

There is an increasing recognition of the damaging role played by oxygen radicals in mediating necrotic neuronal injury. As such, it becomes important to understand the transport mechanisms that help maintain appropriate levels of small molecule antioxidants such as ascorbate in the brain. It has long been known that the transport of dehydroascorbate (DHA) into a variety of cell types is accomplished through the Glut-1 glucose transporter. In this paper, we characterize interactions among the transports of ascorbate, DHA and glucose in hippocampal cultures. We find: (a) sodium-dependent transport of ascorbate in mixed neuronal/glial, pure glial, and neuron-enriched hippocampal cultures; in contrast, we observed no such transport of DHA; (b) such ascorbate transport appeared to be independent of the glucose transporter, in that glucose did not compete for such transport, and overexpression of the Glut-1 glucose transporter did not alter ascorbate uptake; (c) in contrast, ascorbate, at concentrations ranging from 1 to 20 mM inhibited 2-dexogyglucose transport in mixed, glial and enriched neuronal hippocampal cultures; (d) potentially, ascorbate, by acting as an electron donor, could impair the function of molecules involve in the transport or metabolism of glucose. We observed mild inhibition of glucose transport by one unrelated electron donor (glutathione). Moreover, transport was also inhibited by an ascorbate analog which is not an electron donor. Thus, we conclude that ascorbate transport in hippocampal neurons and glia occurs independent of the glucose transporter but that, nevertheless, ascorbate, at concentrations generally thought to be supraphysiological, has the potential for disrupting glucose transport.

Topics: Animals; Ascorbic Acid; Brain Injuries; Carbon Radioisotopes; Cells, Cultured; Dehydroascorbic Acid; Deoxyglucose; Drug Interactions; Fetus; Glucose; Glucose Transporter Type 1; Glutathione; Hippocampus; Monosaccharide Transport Proteins; Nerve Degeneration; Neuroglia; Neurons; Oxidative Stress; Rats

Calcineurin is a serine/threonine phosphatase involved in a wide range of cellular responses to calcium mobilizing signals. Previous evidence supports the notion of the existence of a redox regulation of this enzyme, which might be relevant for neurodegenerative processes, where an imbalance between generation and removal of reactive oxygen species could occur. In a recent work, we have observed that calcineurin activity is depressed in two models for familial amyotrophic lateral sclerosis (FALS) associated with mutations of the antioxidant enzyme Cu,Zn superoxide dismutase (SOD1), namely in neuroblastoma cells expressing either SOD1 mutant G93A or mutant H46R and in brain areas from G93A transgenic mice. In this work we report that while wild-type SOD1 has a protective effect, calcineurin is oxidatively inactivated by mutant SOD1s in vitro; this inactivation is mediated by reactive oxygen species and can be reverted by addition of reducing agents. Furthermore, we show that calcineurin is sensitive to oxidation only when it is in an 'open', calcium-activated conformation, and that G93A-SOD1 must have its redox-active copper site available to substrates in order to exert its pro-oxidant properties on calcineurin. These findings demonstrate that both wild-type and mutant SOD1s can interfere directly with calcineurin activity and further support the possibility of a relevant role for calcineurin-regulated biochemical pathways in the pathogenesis of FALS.

Topics: Aerobiosis; Amyotrophic Lateral Sclerosis; Antioxidants; Ascorbic Acid; Calcineurin; Calcium; Copper; Dithiothreitol; Enzyme Activation; Humans; Nerve Degeneration; Oxidation-Reduction; Point Mutation; Reactive Oxygen Species; Recombinant Proteins; Superoxide Dismutase

The role of ascorbic acid on dopamine (DA) oxidation-mediated cytotoxicity was studied using the PC12 cell line. DA cytotoxicity was slightly attenuated by ascorbic acid, whereas the cytotoxicity of 6-hydroxydopamine (6-OHDA), a DA oxidation product, was markedly potentiated. To elucidate the relationship between the ascorbic acid effect and the degree of DA oxidation, ascorbic acid was added in a time-dependent fashion after DA treatment. We found greater cell death the later ascorbic acid was applied. Treatment of cells with glutathione alleviated DA- and 6-OHDA-induced cell death, while L-buthionine sulfoximine potentiated DA and 6-OHDA cytotoxicity. Ascorbic acid combined with glutathione eliminated the toxicity of DA and 6-OHDA. These results suggest that the interaction between DA and ascorbic acid is dependent upon the degree of DA oxidation and glutathione availability.

Topics: Animals; Ascorbic Acid; Buthionine Sulfoximine; Dopamine; Dose-Response Relationship, Drug; Drug Interactions; Glutathione; Nerve Degeneration; Neuroprotective Agents; Neurotoxins; Oxidative Stress; Oxidopamine; Parkinson Disease; PC12 Cells; Pharmacokinetics; Rats

Following reports that ascorbic acid (AA) blocks NMDA receptors, we examined its possible neuroprotective properties in vivo (gerbil bilateral carotid artery occlusion model: BCAO) and in vitro (ischaemia-induced dopamine (DA) release in brain slices). Five minutes of BCAO caused substantial cell loss of 90-95% and 40-50% in gerbil CA1 hippocampus and striatum, respectively, measured in haematoxylin and eosin-stained sections, 5 days post-insult. AA (500 mg kg(-1) day(-1) i.p. for 312 days, first dose 1 h before occlusion) significantly (P<0.05) reduced striatal cell loss (from 40 to 13%) while only reducing CA1 cell loss from 95 to 88%. A lower dose (250 mg kg(-1) day(-1) i.p. for 312 days) was ineffective in either region. AA (750 mg kg(-1) day(-1) i.p. for 312 days) caused significant striatal protection (cell loss reduced from 49 to 20%) if treatment was initiated 1 h before occlusion. Initiation of treatment immediately post occlusion did not cause significant protection. Neither treatment regime protected CA1 hippocampus. In separate experiments we examined the effect of AA on DA release, monitored by voltammetry, in an in vitro model of striatal ischaemia. Four DA release variables were measured: T(on)--time from initiation of ischaemia to the onset of DA release, T(pk)--the time from onset of DA release to maximum, deltaDA/deltat--the mean rate of DA release and [DA](max)-- the maximum extracellular DA concentration. Control values in drug-naive slices were: T(on)=193+/-8 s, T(pk) = 24 +/- 4 s, [DA](max) = 69 +/- 6 microM and deltaDA/deltat = 4.2 +/- 0.7 microM s(-1) (means+/-S.E.M., n=15). 212 h pretreatment with AA (0.4 to 10 mM) did not affect T(on) or [DA](max) but increased T(pk) and decreased deltaDA/deltat (P<0.05) with an EC50 of 1.66 mM. NMDA (100 microM) shortened T(on). N-ethylmaleimide (20 microM) had no effect on the response to AA but potentiated the action of NMDA on T(on). AA (2 or 10 mM) had no effect on the response to NMDA. We conclude that AA is neuroprotective against global ischaemia in the striatum and that some of this action may be due to attenuation of ischaemia-induced DA release. This action is mediated neither by blockade of the NMDA receptor nor modulation of its redox status.

Topics: Alkylating Agents; Animals; Ascorbic Acid; Brain Ischemia; Corpus Striatum; Dopamine; Drug Interactions; Electrochemistry; Ethylmaleimide; Gerbillinae; Hippocampus; Male; N-Methylaspartate; Nerve Degeneration; Neuroprotective Agents; Rats; Rats, Wistar

Topics: Animals; Ascorbic Acid; Brain; Cell Line; Ferrous Compounds; Free Radical Scavengers; Hippocampus; Imidazoles; Ischemic Attack, Transient; Lactates; Malondialdehyde; Mitochondria; Mitochondria, Liver; Mitochondrial Swelling; Nerve Degeneration; Neurons; Neuroprotective Agents; Rats; Reperfusion Injury

Sodium nitroprusside (disodium nitroferricyanide) has been suggested to cause cytotoxicity through either the release of cyanide and/or nitric oxide. The present study investigated a possible mechanism that after a brief release of nitric oxide, iron moiety of breakdown products of sodium nitroprusside could cause a long lasting oxidative stress, such as hydroxyl radical generation, lipid peroxidation and cytotoxicity. Intranigral administration of sodium nitroprusside (0-16.8 nmol) to rats induced an acute increase in lipid peroxidation in the substantia nigra and a chronic dopamine depletion in the caudate nucleus. Photodegraded (nitric oxide-exhausted) sodium nitroprusside, however, still produced lipid peroxidation and neurotoxicity in the midbrain. Moreover, non-iron containing nitric oxide-donor compounds, such as S-nitroso-N-acetylpenicillamine, did not cause oxidative brain injury in vivo suggesting that nitric oxide may not mediate neurotoxicity induced by sodium nitroprusside. Additional in vitro studies demonstrated that both freshly prepared (nitric oxide donor) and photodegraded (nitric oxide-exhausted) sodium nitroprusside generated hydroxyl radicals in the presence of ascorbate and also increased lipid peroxidation in brain homogenates. These pro-oxidative effects of sodium nitroprusside were blocked by nitric oxide, S-nitroso-N-acetylpenicillamine, oxyhemoglobin, and deferoxamine (iron chelator). The present results suggest that iron moiety, rather than nitric oxide, may mediate the pro-oxidative properties of sodium nitroprusside. With this new information in mind, the misuse of sodium nitroprusside as a selective nitric oxide donor in both basic and clinical uses should be urgently addressed.

Topics: Animals; Ascorbic Acid; Brain Injuries; Deferoxamine; Hydrogen Peroxide; Hydroxyl Radical; In Vitro Techniques; Iron; Lipid Peroxidation; Male; Nerve Degeneration; Nitric Oxide; Nitroprusside; Oxidative Stress; Oxyhemoglobins; Penicillamine; Rats; Rats, Sprague-Dawley

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease in which upper and lower motoneurons progressively deteriorate and die. Neuronal damage is most evident in the lower central nervous system, and death generally occurs following central respiratory failure. Proposed and demonstrated mechanisms for amyotrophic lateral sclerosis are diverse, and include altered superoxide dismutase and neurofilament proteins, autoimmune attack, and hyperglutamatergic activity. However, they do not account for the late onset of the disease, its earlier onset in males, and the differential vulnerability of neurons located in the brainstem and spinal cord. It is proposed here that, within the context of a specific defect such as altered superoxide dismutase, age-dependent decline in ascorbate availability triggers the disease. A role for ascorbate, which is found in millimolar levels in neurons, is suggested by a number of consistencies: 1) superoxide radicals being a common substrate for superoxide dismutase and ascorbate; 2) a close association between central nervous system ascorbate levels and injury tolerance; 3) a steady decline in ascorbate plasma levels and cellular availability with age; 4) plasma ascorbate levels being lower in males; 5) an association of ascorbate release with motor activity in central nervous system regions, in vivo; 6) the coupling of brain-cell ascorbate release with glutamate uptake; 7) possible roles for ascorbate modulation of N-methyl-D-aspartate receptor activity; 9) the ability of ascorbate to prevent peroxynitrite anion formation; and 10) evidence supporting the scorbutic guinea pig as a model for amyotrophic lateral sclerosis. Emphasis is placed on the probable competition between superoxide dismutase and ascorbate within the context of a primary defect of metal-binding or metal access in high-concentration proteins such as superoxide dismutase and human heavy neurofilaments. Finally, distinct features of alpha-motoneuronal physiology suggest that cell physiological characteristics such as high metabolic activity and extensive calcium dynamics may render neurons differentially vulnerable in amyotrophic lateral sclerosis.

Topics: Amyotrophic Lateral Sclerosis; Animals; Ascorbic Acid; Biological Availability; Central Nervous System; Humans; Models, Neurological; Nerve Degeneration; Superoxide Dismutase

Reactive oxygen species (ROS) are supposed to be involved in neurodegenerative processes like Parkinson's or Alzheimer's disease. Beside this there are an increasing number of studies indicating an involvement of ROS in traumatic brain injury. We therefore studied the potential role of astrocytes against neurotoxic effects of ROS in cocultures of rat cortical astrocytes with regenerating postnatal retinal ganglion cells (RGC). The sydnonimine SIN-1, which spontaneously decomposes to yield nitric oxide (NO) and superoxide anion radicals, led to axonal degeneration at concentrations between 1 microM and 10 microM. Comparable effects were seen after addition of iron salts (Fe2+/Fe3+), which catalyze the generation of hydroxyl radicals. In contrast, in cocultures of RGC with astrocytes or after addition of free radical scavengers there was no neurotoxic/neurodegenerative effect of ROS as compared with control cultures. Vitamin E (1-10 microM) and vitamin C (10-100 microM) abolished the neurotoxic effect of both SIN-1 or iron ions. Beside this, there was an additional effect concerning the number and the length of neurites growing out from the retinal explant: in cocultures both parameters were greatly enhanced. These results suggest that (i) astrocytes are able to protect retinal ganglion cells against ROS-induced oxidative stress, (ii) astrocytes release soluble neurotrophic factors supporting RGC axonal regeneration, and (iii) free radical production after tissue injury may partly contribute to the failure of axonal regeneration in the adult mammalian central nervous system.

Topics: Animals; Ascorbic Acid; Astrocytes; Axons; Coculture Techniques; Free Radical Scavengers; Iron; Molsidomine; Nerve Degeneration; Neurites; Neuroprotective Agents; Rats; Reactive Oxygen Species; Reference Values; Retinal Ganglion Cells; Vitamin E

Exposure of the neurotransmitters dopamine (1a) and norepinephrine (1b), as well as of other catechol compounds (1c-e), to nitric oxide (NO) in aerated phosphate buffer at room temperature leads to the corresponding 6-nitroderivatives (2a-e) in yields higher than 80%. Formation of nitration products depends on the presence of oxygen and is inhibited by excess ascorbic acid, whereas sulfhydryl compounds, e.g. cysteine, and scavengers of reactive oxygen species, such as catalase and superoxide dismutase, exert no significant inhibitory effect. O-Methylated catechols are poorly or not reactive toward NO. These and other observations are consistent with a mechanism involving coupling of a semiquinone radical with NO or a higher oxide, e.g. nitrogen dioxide (NO2). The observed formation of potentially toxic 6-nitrocatecholamines under physiologically relevant conditions may open new perspectives to an understanding of the biochemical processes underlying NO-induced toxicity and neuronal degeneration.

Topics: Ascorbic Acid; Catecholamines; Molecular Structure; Nerve Degeneration; Neurotransmitter Agents; Nitric Oxide; Oxygen

Postmortem caudate and substantia nigra tissue samples from human parkinsonian patients (PD) and age-matched controls (NC) were analyzed for uric acid (UA), dopamine (DA), and ascorbic acid (AA) by HPLC/UV/ED. Uric acid and DA levels were significantly lower in the substantia nigra of PD by 54% and 85%, respectively. In the caudate, DA levels were significantly lower while UA levels were nonsignificantly reduced (0.10 < p < 0.05). Ascorbic acid levels were not significantly different from the controls in either brain region. Conditions favorable for oxidative stress were evaluated by measuring the oxidation of DA in individual brain homogenates. The rate constant for DA oxidation in control caudate was 0.34 x 10(-2) min-1 and in parkinsonian caudate was 4.20 x 10(-2) min-1. In control and parkinsonian substantia nigra DA oxidation rate constants were 2.82 x 10(-2) min-1 and 4.57 x 10(-2) min-1, respectively. Addition of UA or catalase to parkinsonian homogenate decreased the rate of DA oxidation, while addition of uricase to control homogenate increased the rate of DA oxidation. The data support the hypothesis that UA is decreased in nigrostriatal dopamine neurons in parkinsonian patients which contributes to an environment susceptible to oxidative stress, particularly through dopamine oxidation reactions.

Topics: Aged; Ascorbic Acid; Brain Chemistry; Dopamine; Female; Humans; Male; Nerve Degeneration; Neural Pathways; Oxidation-Reduction; Parkinson Disease; Substantia Nigra; Tissue Extracts; Uric Acid

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Brain; Brain Chemistry; Dopamine; Dose-Response Relationship, Drug; Fluorescence; Guinea Pigs; Histocytochemistry; Hydroxydopamines; In Vitro Techniques; Iris; Male; Methyltyrosines; Myocardium; Nerve Degeneration; Neurons; Norepinephrine; Tritium; Tyrosine 3-Monooxygenase