ascorbic-acid and Brain-Ischemia

Tissue plasminogen activator (t-PA) is the only FDA-approved drug for acute ischemic stroke treatment, but its clinical use is limited due to the narrow therapeutic time window and severe adverse effects, including hemorrhagic transformation (HT) and neurotoxicity. One of the potential resolutions is to use adjunct therapies to reduce the side effects and extend t-PA's therapeutic time window. However, therapies modulating single target seem not to be satisfied, and a multitarget strategy is warranted to resolve such complex disease. Recently, large amount of efforts have been made to explore the active compounds from herbal supplements to treat ischemic stroke. Some natural compounds revealed both neuro- and bloodbrain- barrier (BBB)-protective effects by concurrently targeting multiple cellular signaling pathways in cerebral ischemia-reperfusion injury. Thus, those compounds are potential to be one-drug-multi-target agents as combined therapy with t-PA for ischemic stroke. In this review article, we summarize current progress about molecular targets involving in t-PA-mediated HT and neurotoxicity in ischemic brain injury. Based on these targets, we select 23 promising compounds from currently available literature with the bioactivities simultaneously targeting several important molecular targets. We propose that those compounds merit further investigation as combined therapy with t-PA. Finally, we discuss the potential drawbacks of the natural compounds' studies and raise several important issues to be addressed in the future for the development of natural compound as an adjunct therapy.

Topics: Animals; Ascorbic Acid; Biological Products; Brain Ischemia; Drug Therapy, Combination; Flavonoids; Humans; Stroke; Thrombolytic Therapy; Tissue Plasminogen Activator; Treatment Outcome

Acute ischemic stroke is a leading cause of death and severe disability in industrialised countries and also in many developing countries. An excessive amount of free radicals is generated during cerebral ischemia, which significantly contributes to brain damage. Therefore, an increasing interest has been devoted to the potential benefits of antioxidant compounds in ischemic stroke patients. In this review, we examined the most relevant observational studies concerning the relationship between dietary antioxidants and ischemic stroke as well as clinical trials investigating the effects of single or multiple antioxidant supplementation in the prevention or treatment of acute ischemic stroke. Furthermore, we reviewed the most promising antioxidant compounds, i.e. dehydroascorbic acid, alpha-tocotrienol, gamma-tocopherol, flavonoids, resveratrol and gingko biloba, tested in animal models of acute ischemic stroke. Finally, we carefully evaluated the reasons for the discrepancy between experimental and clinical studies, and provided recommendations to improve the translation of the results obtained in animal models to patients with acute ischemic stroke.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Brain Ischemia; Diet; Fruit; Humans; Oxidative Stress; Risk; Stroke; Vegetables; Vitamin A; Vitamin E

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Dehydroascorbic Acid; Humans; Stroke

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Chromans; Corpus Striatum; Hippocampus; Ischemic Attack, Transient; Male; Neurons; Rats; Rats, Wistar; Reperfusion Injury; Structure-Activity Relationship

To determine the optimal duration of energy corrective treatment of ischemic stroke (II) with cytoflavin or ascorbic acid.. A multicenter randomized clinical trial included 185 patients, aged 40-75 years. Patients were randomized into 3 groups: the control group (n=64) received ascorbic acid; cytoflavin group 1 (n=72) was treated for 10 days and cytoflavin group 2 (n=49) for 20 days. In all groups, mean NIHSS score was 13, 42.2% of patients scored ≥14 and on admission, 42.2% of patients had consciousness impairment of different severity.. Cytoflavin treatment was more efficient than ascorbic acid that can be explained by different pharmacologic mechanisms. Treatment with cytoflavin for 10 days resulted in a significant decrease of ischemia zone volume by 25.2%, treatment with cytoflavin for 20 days - by 29.0%, which was associated with better outcomes in neurologic and functional status. Ascorbic acid demonstrated no effect on morphologic parameters. Prolonged treatment with cytoflavin in critically ill patients led to significant improvement in clinical and morphologic variables compared to the 10-day course. In patients with less severe condition comparable results were obtained.. Our data justify the need for personalized integrated antioxidant and energy correction therapy.

Topics: Adult; Aged; Antioxidants; Ascorbic Acid; Brain Infarction; Brain Ischemia; Drug Combinations; Female; Flavin Mononucleotide; Humans; Inosine Diphosphate; Male; Middle Aged; Niacinamide; Succinates; Treatment Outcome

To test whether supplementary antioxidants immediately following acute ischaemic stroke will enhance antioxidant capacity and mitigate oxidative damage.. A randomised controlled trial.. A university teaching hospital.. A total of 48 acute ischaemic stroke patients within 12 h of symptom onset.. Daily oral 800 IU (727 mg) of alpha-tocopherol and 500 mg of vitamin C (n = 24), or no treatment (n = 24) for 14 days. Treatment group and controls were matched for stroke subtype and age.. alpha-Tocopherol, ascorbic acid, total antioxidant capacity (TAOC), plasma malondialdehyde (MDA) and C-reactive protein (CRP) before treatment, at day 7 and day 14 following recruitment.. In all, 14 days of vitamin supplementation significantly improved plasma alpha-tocopherol and ascorbic concentrations in the treatment group compared with the decrease seen in the control group (P < 0.005 for difference in cumulative changes). TAOC increased significantly in the treatment group compared with controls (P < 0.003). There was a significant reduction in plasma MDA concentration in the treatment group, in contrast to the increase seen in the control group (P < 0.002). After adjusting for clinical complications CRP concentrations within 90 days postinfarct were significantly lower in the treatment group compared with controls.. Supplementation with antioxidant vitamins within 12 h of onset of acute ischaemic stroke increased antioxidant capacity, reduced lipid peroxidation products and may have an anti-inflammatory effect.. Sheffield Teaching Hospital NHS Trust.

Topics: Acute Disease; Aged; Aged, 80 and over; alpha-Tocopherol; Antioxidants; Ascorbic Acid; Brain Ischemia; C-Reactive Protein; Dietary Supplements; Female; Humans; Lipid Peroxidation; Male; Malondialdehyde; Oxidative Stress

Inflammatory response is a critical component of the complex pathophysiological response to stroke. Vitamin C has been shown to have important roles in cell performance and vascular function. In this study, we compared the nutritional status and levels of inflammatory markers between stroke cases and controls and assessed which antioxidant was associated with levels of inflammatory markers and oxidative stress among cases and controls.. We evaluated the nutritional status and measured plasma levels of vitamins C and E, uric acid, serum levels of C-reactive protein (CRP), the cytokines tumor necrosis factor-alpha and interleukin-1beta, intercellular adhesion molecule-1 (ICAM-1) and chemokine monocyte chemoattractant protein-1 (MCP-1), prostaglandins PGE2 and PGI2, and 8-isoprostanes (8-epiPGF2alpha) for 15 patients with ischemic stroke within 2 to 5 days after stroke onset and for 24 control subjects.. Stroke patients had significantly lower plasma levels of vitamin C than did controls. Among stroke patients, CRP was significantly elevated, as were the ICAM-1, MCP-1, and 8-epiPGF2alpha, but the prostaglandins PGE2 and PGI2 were significantly reduced. Interestingly, vitamin C concentration was significantly inversely correlated with the levels of CRP and 8-epiPGF2alpha among stroke patients, and 8-epiPGF2alpha was significantly associated with the levels of CRP. Uric acid was also elevated among stroke patients.. Lower vitamin C concentration, higher serum levels of inflammatory (CRP, ICAM-1, MCP-1) and oxidative stress (8-epiPGF2alpha) markers, and lower PGI2 and PGE2 concentrations among stroke patients indicate the presence of an inflammatory response associated with stroke.

Topics: Aged; Antioxidants; Ascorbic Acid; Biomarkers; Brain Ischemia; C-Reactive Protein; Chemokine CCL2; Cytokines; Diet; Dinoprost; Humans; Inflammation Mediators; Intercellular Adhesion Molecule-1; Middle Aged; Neuropsychological Tests; Nutritional Status; Oxidative Stress; Prostaglandins; Reference Values; Stroke; Time Factors; Uric Acid; Vitamin E

Anti-ischemic effect of angiotensin-converting enzyme inhibitor--chinapril was examined by exercise tolerance test [ETT] in randomised, cross-over double blind comparison in 20 pts with coronary artery disease treated with beta-blockers and nitrates. After 8 weeks of chinapril treatment maximal work capacity and exercise duration were significantly greater in comparison with baseline values, respectively: 7,8 vs 6,7 METs (p < 0,05) and 416 vs 335 s (p < 0,05). Time to ST segment depression was significantly longer after chinapril treatment: 394 vs 298 s (placebo) p = 0,01) vs 277 s (baseline), p = 0,008. The number of patients with exercise ST depression was significantly lower (63% vs 100%). Rate pressure product wasn't changed after chinapril treatment. Vitamin C therapy did not have influence on ischemia signs in exercise tolerance test.

Topics: Adrenergic beta-Antagonists; Angiotensin-Converting Enzyme Inhibitors; Ascorbic Acid; Brain Ischemia; Coronary Artery Disease; Cross-Over Studies; Double-Blind Method; Exercise Test; Female; Humans; Male; Middle Aged; Nitrates

Experimental studies provide evidence of an association between ischemic stroke and increased oxidative stress, but data in humans are still limited and controversial. The purpose of this study was to investigate the time course of plasma antioxidant changes in ischemic stroke patients.. Plasma antioxidants, including water-soluble (vitamin C and uric acid) and lipid-soluble (vitamins A and E) compounds as well as antioxidant enzyme activities in plasma (superoxide dismutase [SOD] and glutathione peroxidase) and erythrocytes (SOD), were measured by high-performance liquid chromatography (antioxidant vitamins) and by spectrophotometry (antioxidant enzymes) in 38 subjects (25 men and 13 women aged 77.2+/-7.9 years) with acute ischemic stroke of recent onset (<24 hours) on admission, after 6 and 24 hours, and on days 3, 5, and 7. Antioxidant levels in patients on admission were compared with those of age- and sex-matched controls.. Mean antioxidant levels and activities in patients on admission were lower than those of controls and showed a gradual increase over time. Patients with the worst early outcome (death or functional decline) had higher vitamin A and uric acid plasma levels and lower vitamin C levels and erythrocyte SOD activity than those who remained functionally stable.. These results suggest that the majority of antioxidants are reduced immediately after an acute ischemic stroke, possibly as a consequence of increased oxidative stress. A specific antioxidant profile is associated with a poor early outcome.

Topics: Aged; Analysis of Variance; Antioxidants; Ascorbic Acid; Brain Ischemia; Chromatography, High Pressure Liquid; Disease Progression; Erythrocytes; Female; Glutathione Peroxidase; Humans; Longitudinal Studies; Male; Oxidative Stress; Severity of Illness Index; Spectrophotometry; Stroke; Superoxide Dismutase; Treatment Outcome; Uric Acid; Vitamin A; Vitamin E

Vitamin C has recently been identified as an epigenetic regulator by activating ten-eleven translocases (TETs), enzymes involved in generating DNA hydroxymethylcytosine (5hmC). Currently, we investigated whether high-dose vitamin C promotes neuroprotection through epigenetic modulation of 5hmC, if there are sex-specific differences in outcome, and the therapeutic potential of vitamin C in stroke-related comorbidities in adult mice. Post-stroke treatment with ascorbate (reduced form), but not dehydroascorbate (oxidized form), increased TET3 activity and 5hmC levels and reduced infarct following focal ischemia. Hydroxymethylation DNA immunoprecipitation sequencing showed that ascorbate increased 5hmC across the genome and specifically in promoters of several stroke pathophysiology-related genes, particularly anti-inflammatory genes. Ascorbate also decreased markers of oxidative stress, mitochondrial fragmentation, and apoptosis in cortical peri-infarct neurons and promoted motor and cognitive functional recovery in both sexes via TET3. Furthermore, post-stroke ascorbate treatment reduced infarct volume and improved motor function recovery in aged, hypertensive and diabetic male and female mice. Delayed ascorbate treatment at 6 h of reperfusion was still effective at reducing infarct volume and motor impairments in adult mice. Collectively, this study shows that post-stroke treatment with high-dose ascorbate protects the brain through epigenetic reprogramming and may function as a robust therapeutic against stroke injury.

Topics: 5-Methylcytosine; Animals; Ascorbic Acid; Brain; Brain Injuries; Brain Ischemia; DNA; Epigenesis, Genetic; Female; Infarction; Male; Mice; Neuroprotection; Stroke

Stroke is a major public health problem and ranks third most common cause of death in adults worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury, mainly caused by oxidative/nitrosative stress injury, after revascularization therapy can result in worsening outcomes. For better clinical prognosis, more and more studies have focused on the pharmaceutical neuroprotective therapies against free radical damage. The impact of vitamin C (ascorbic acid) on oxidative stress-related diseases is moderate because of its limited oral bioavailability and rapid clearance. However, recent evidence of the clinical benefit of parenteral vitamin C administration has emerged, especially in critical care. In this study we demonstrated that parenteral administration of vitamin C significantly improved neurological deficits and reduced brain infarction and brain edema by attenuating the transient middle cerebral artery occlusion (tMCAO)-induced nitrosative stress, inflammatory responses, and the resultant disruptions of blood brain barrier and cerebral neuronal apoptosis. These results suggest that parenteral administration of vitamin C has potential as an adjuvant agent with intravenous thrombolysis or endovascular thrombectomy in acute treatment of ischemic stroke.

Topics: Animals; Apoptosis; Ascorbic Acid; Blood-Brain Barrier; Brain; Brain Ischemia; Infarction, Middle Cerebral Artery; Neuroprotective Agents; Rats; Stroke; Tissue Plasminogen Activator

It is of interest to in vivo monitor the co-dynamics of different substances. However, the tracking of multiple species is still challenging. In this work, we demonstrate an in vivo electrochemical method by using multi-potential step amperometry to in vivo detect ascorbic acid (AA) and oxygen (O2) simultaneously. In order to achieve good selectivity and high sensitivity for both AA and O2, we design a cobalt corrole [Co(tpfc)(py)2] (tpfc = 5,10,15-tris(penta-fluorophenyl) corrole, py = pyridine, denoted as Co-TPFC) and carbon nanotube nanocomposite to modify a carbon fiber microelectrode (Co-TPFC/MWNT/CFE). This Co-TPFC/MWNT/CFE exhibits excellent electrocatalytic properties towards the reduction of O2 preceding a 4e process and facilitates the oxidation of AA at low potential in the physiological environment. Based on this, we realize simultaneous detection of AA and O2 using two-potential steps (one cathodic (-0.2 V) and the other anodic (+0.05 V)) with 1 second step time. Both in vitro and in vivo experiments proved the feasibility of this method. This demonstrated strategy is useful for us to understand various physiological and pathological processes associated with O2 and AA co-dynamics, and also provides an idea for detecting multiple substances simultaneously.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Carbon; Cobalt; Electrochemical Techniques; Male; Metalloporphyrins; Microelectrodes; Nanocomposites; Nanotubes, Carbon; Oxidation-Reduction; Oxygen; Rats, Sprague-Dawley

As a promising therapeutic treatment, ischemic postconditioning has recently received considerable attention. Although the neuroprotection effect of postconditioning has been observed, a reliable approach that can evaluate the neuroprotective efficiency of postconditioning treatment during the acute period after ischemia remains to be developed. This study investigates the dynamics of cortex ascorbic acid during the acute period of cerebral ischemia before and after ischemic postconditioning with an online electrochemical system (OECS). The cerebral ischemia/reperfusion injury and the neuronal functional outcome are evaluated with triphenyltetrazolium chloride staining, immunohistochemistry, and electrophysiological recording techniques. Electrochemical recording results show that cortex ascorbic acid sharply increases 10 min after middle cerebral artery occlusion and then reaches a plateau. After direct reperfusion following ischemia (i.e., without ischemic postconditioning), the cortex ascorbic acid further increases and then starts to decrease slowly at a time point of about 40 min after reperfusion. In striking contrast, the cortex ascorbic acid drops and recovers to its basal level after ischemic postconditioning followed by reperfusion. With the recovery of cortex ascorbic acid, ischemic postconditioning concomitantly promotes the recovery of neural function and reduces the oxidative damage. These results demonstrate that our OECS for monitoring cortex ascorbic acid can be used as a platform for evaluating the neuroprotective efficiency of ischemic postconditioning in the acute phase of cerebral ischemia, which is of great importance for screening proper postconditioning parameters for preventing ischemic damages.

Topics: Acute Disease; Animals; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Disease Models, Animal; Electrophysiological Phenomena; Infarction, Middle Cerebral Artery; Ischemic Postconditioning; Male; Monitoring, Physiologic; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Stroke

Recent evidences suggest that cerebral ischemia-reperfusion insult plays significant role in pathogenic diseases like Alzheimer's disease (AD) and other neurodegenerative diseases. Toxic reactive oxygen species (ROS) generated by induced oxidative stress in the episodes of cerebral ischemia-reperfusion (CIR) plays major role in neurodegeneration. As the prime source of ROS generation, neuronal mitochondria, the cellular energy metabolic centre experience severe damage because of CIR-induced oxidative stress. The process of mitochondrial dysfunction is accelerated by CIR that may pave the pathway for neurodegeneration in AD among aged individuals. Prevention of CIR injury may be a shunt in order to minimize the risk of dementia of Alzheimer's type in aged individuals. The use of chemical antioxidants in CIR is not suitable as the blood- brain barrier (BBB) doesn't allow the entry of molecules from blood circulation into the brain. Thus L-ascorbic acid loaded polylactide nanocapsules were prepared and fed orally to assess the role of nanocapsulated ascorbic acid (NAA) against CIR induced oxidative injury in mitochondrial region of rat brains. Mitochondrial injury was assessed by the extent of lipid peroxidation and in situ antioxidant enzyme status. The levels of cytochrome c (cyt c), cyclooxygenase- 2 (COX-2) and iNOS were determined. Results showed that in comparison to free ascorbic acid (AA), NAA exerted better protection to the brain mitochondria by preventing oxidative damage in ROS mediated CIR injury.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Brain Ischemia; Catalase; Disease Models, Animal; Female; Glutathione Peroxidase; Glutathione Reductase; Lipid Peroxidation; Mitochondria; Nanocapsules; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Superoxide Dismutase

A simple and novel method for evaluating antioxidants in complex biological fluids has been developed based on the interaction of dye-labeled single-strand DNA (ssDNA) and polydopamine (PDA). Due to the interaction between ssDNA and PDA, the fluorescence of dye-labeled ssDNA (e.g., FITC-ssDNA, as donor) can be quenched by PDA (as acceptor) to the fluorescence "off" state through Förster resonance energy transfer (FRET). However, in the presence of various antioxidants, such as glutathione (GSH), ascorbic acid (AA), cysteine (Cys), and homocysteine (Hcys), the spontaneous oxidative polymerization reaction from DA to PDA would be blocked, resulting in the freedom of FITC-ssDNA and leading to the fluorescence "on" state. The sensing system shows great sensitivity for the monitoring of antioxidants in a fluorescent "turn on" format. The new strategy also exhibits great selectivity and is free from the interferences of amino acids, metal ions and the biological species commonly existing in brain systems. Moreover, by combining the microdialysis technique, the present method has been successfully applied to monitor the dynamic changes of the striatum antioxidants in rat cerebrospinal microdialysates during the normal/ischemia/reperfusion process. This work establishes an effective platform for in vivo monitoring antioxidants in cerebral ischemia model, and promises new opportunities for the research of brain chemistry, neuroprotection, physiological, and pathological events.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Cysteine; DNA; Fluorescent Dyes; Glutathione; Homocysteine; Indoles; Polymers; Rats; Spectrometry, Fluorescence

Less than 8.5% of ischemic stroke patients receive clot-busting drugs within the narrow time needed to reduce injury. Thus, there is need for an easily-accessible delayed post-stroke drug treatment to improve functional recovery. Various combinations of fluoxetine, simvastatin, and ascorbic acid were given to healthy rats to assess impact on neurogenesis versus controls. Fluoxetine combined with simvastatin and ascorbic acid produced a 19-fold increase in neurogenesis versus controls in healthy rats; fluoxetine alone produced 10-fold increase. We next tried a couple of drug combinations versus control in endothelin-induced stroked rats. Combined fluoxetine/ simvastatin/ascorbic acid treatment, given to stroked rats 20-26 hours after stroke induction and continued for 31 days, produced strong recovery as measured by Montoya staircase test (mean recovery to 85% of pre-stroke function) and Forelimb Asymmetry test (mean recovery to 90% of pre-stroke function). Fluoxetine and ascorbic acid without simvastatin only produced ~50% of recovery produced by the 3-drug combination. Our results indicate that combined treatment of Fluoxetine, simvastatin and ascorbic acid represents a promising delayed stroke treatment that greatly improves functional recovery in rats and warrants further study in human patient populations. This work formed the basis for a patent submission (US20130065924A1) Composition and method for treatment of neurodegeneration.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Drug Therapy, Combination; Female; Fluoxetine; Male; Neurogenesis; Rats; Rats, Long-Evans; Rats, Wistar; Recovery of Function; Simvastatin; Stroke

In this study, we report a novel and efficient fluorescence probe synthesized by Tris(hydroxymethyl)aminomethane-derived carbon dots (CDs)-modified hexagonal cobalt oxyhydroxide(CoOOH) nanoflakes (Tris-derived CDs-CoOOH) for monitoring of cerebral ascorbic acid (AA) in brain microdialysate. The as-prepared Tris-derived CDs with the fluorescence quantum yield of 7.3% are prepared by a one-step pyrolysis strategy of the sole precursor and used as the signal output. After being hybridized with CoOOH nanoflakes to form Tris-derived CDs-CoOOH, the luminescence of the Tris-derived CDs can be efficiently quenched by CoOOH via fluorescence resonance energy transfer (FRET). Due to the specific redox reaction between the enediol group of AA and hexagonal CoOOH nanoflakes, AA can reduce the hexagonal CoOOH nanoflakes in the Tris-derived CDs-CoOOH and lead to collapse of the hybrized structure, then the release of Tris-derived CDs, and thus finally the fluorescence recovery. Moreover, cobalt ions (II), generated by CoOOH nanoflakes oxidizing AA, almost have no obvious interference on the fluorescence probe, i.e., Tris-derived CDs, which could be ascribed to the surface of Tris-derived CDs containing a few strong chelation groups such as amino/carboxyl/thiol groups, instead of plenty of -OH groups with weak chelation with Co(2+). On the basis of this feature, the Tris-derived CDs-CoOOH fluorescent probe demonstrates a linear range from 100 nM to 20 μM with the detection limit of ∼50 nM, i.e., with an improved sensitivity toward AA detection. Compared with other turn-on fluorescent methods using convenient fluorophore-nitroxide fluorescent probes for detection of AA, the method demonstrated here possesses a facial synthesis route, lower limit of detection, and wider linear range, which validates sensing of AA in the cerebral systems during the calm/ischemia process. This study provides a fluorescence assay for the simple yet facial detection of AA in the cerebral systems and assists in the understanding of the biological processes in the physiological and pathological study.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Carbon; Cobalt; Fluorescent Dyes; Limit of Detection; Nanoparticles; Oxides; Rats; Surface Properties; Tromethamine

Stroke is a devastating disease. Both excitotoxicity and oxidative stress play important roles in ischemic brain injury, along with harmful impacts on ischemic cerebral tissue. As guanosine plays an important neuroprotective role in the central nervous system, the purpose of this study was to evaluate the neuroprotective effects of guanosine and putative cerebral events following the onset of permanent focal cerebral ischemia.. Permanent focal cerebral ischemia was induced in rats by thermocoagulation. Guanosine was administered immediately, 1 h, 3 h and 6 h after surgery. Behavioral performance was evaluated by cylinder testing for a period of 15 days after surgery. Brain oxidative stress parameters, including levels of ROS/RNS, lipid peroxidation, antioxidant non-enzymatic levels (GSH, vitamin C) and enzymatic parameters (SOD expression and activity and CAT activity), as well as glutamatergic parameters (EAAC1, GLAST and GLT1, glutamine synthetase) were analyzed.. After 24 h, ischemic injury resulted in impaired function of the forelimb, caused brain infarct and increased lipid peroxidation. Treatment with guanosine restored these parameters. Oxidative stress markers were affected by ischemic insult, demonstrated by increased ROS/RNS levels, increased SOD expression with reduced SOD activity and decreased non-enzymatic (GSH and vitamin C) antioxidant defenses. Guanosine prevented increased ROS/RNS levels, decreased SOD activity, further increased SOD expression, increased CAT activity and restored vitamin C levels. Ischemia also affected glutamatergic parameters, illustrated by increased EAAC1 levels and decreased GLT1 levels; guanosine reversed the decreased GLT1 levels and did not affect the EAAC1 levels.. The effects of brain ischemia were strongly attenuated by guanosine administration. The cellular mechanisms involved in redox and glutamatergic homeostasis, which were both affected by the ischemic insult, were also modulated by guanosine. These observations reveal that guanosine may represent a potential therapeutic agent in cerebral ischemia by preventing oxidative stress and excitotoxicity.

Topics: Animals; Ascorbic Acid; Blotting, Western; Brain Injuries; Brain Ischemia; Catalase; Dose-Response Relationship, Drug; Drug Administration Schedule; Electrocoagulation; Excitatory Amino Acid Transporter 3; Exploratory Behavior; Forelimb; Glutamate Plasma Membrane Transport Proteins; Glutamate-Ammonia Ligase; Glutathione; Guanosine; Lipid Peroxidation; Male; Neuroprotective Agents; Nitric Oxide; Rats, Wistar; Reactive Oxygen Species; Superoxide Dismutase

Developing new tools and technologies to enable recording the dynamic changes of multiple neurochemicals is the essence of better understanding of the molecular basis of brain functions. This study demonstrates a microfluidic chip-based online electrochemical system (OECS) for in vivo continuous and simultaneous monitoring of glucose, lactate, and ascorbate in rat brain. To fabricate the microfluidic chip-based detecting system, a microfluidic chip with patterned channel is developed into an electrochemical flow cell by incorporating the chip with three surface-modified indium-tin oxide (ITO) electrodes as working electrodes, a Ag/AgCl wire as reference electrode, and a stainless steel tube as counter electrode. Selective detection of ascorbate is achieved by the use of single-walled carbon nanotubes (SWNTs) to largely facilitate the electrochemical oxidation of ascorbate, while a dehydrogenase-based biosensing mechanism with methylene green (MG) adsorbed onto SWNTs as an electrocatalyst for the oxidation of dihydronicotiamide adenine dinucleotide (NADH) is employed for biosensing of glucose and lactate. To avoid the crosstalk among three sensors, the sensor alignment is carefully designed with the SWNT-modified electrode in the upstream channel and paralleled glucose and lactate biosensors in the downstream channels. With the microfluidic chip-based electrochemical flow cell as the detector, an OECS is successfully established by directly integrating the microfluidic chip-based electrochemical flow cell with in vivo microdialysis. The OECS exhibits a good linear response toward glucose, lactate, and ascorbate with less crosstalk. This property, along with the high stability and selectivity, enables the OECS for continuously monitoring three species in rat brain following brain ischemia.

Topics: Animals; Ascorbic Acid; Biosensing Techniques; Brain Chemistry; Brain Ischemia; Electrochemistry; Electrodes; Glucose; Indicators and Reagents; Indium; Lactic Acid; Male; Microcomputers; Microfluidic Analytical Techniques; Oxidation-Reduction; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Tin Compounds

The objective of the present study was to prepare a stable iv injectable formulation of ascorbic acid and α-tocopherol in preventing the cerebral ischemia. Different niosomal formulations were prepared by Span and Tween mixed with cholesterol. The physicochemical characteristics of niosomal formulations were evaluated in vitro. For in vivo evaluation, the rats were made ischemic by middle cerebral artery occlusion model for 30 min and the selected formulation was used for determining its neuroprotective effect against cerebral ischemia. Neuronal damage was evaluated by optical microscopy and transmission electron microscopy. The encapsulation efficiency of ascorbic acid was increased to more than 84% by remote loading method. The cholesterol content of the niosomes, the hydrophilicity potential of the encapsulated compounds, and the preparation method of niosomes were the main factors affecting the mean volume diameter of the prepared vesicles. High physical stability of the niosomes prepared from Span 40 and Span 60 was demonstrated due to negligible size change of vesicles during 6 months storage at 4-8(°)C. In vivo studies showed that ST60/Chol 35 : 35 : 30 niosomes had more neuroprotective effects against cerebral ischemic injuries in male rats than free ascorbic acid.

Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Chemistry, Pharmaceutical; Disease Models, Animal; Infarction, Middle Cerebral Artery; Liposomes; Male; Neurons; Particle Size; Rats, Wistar; Reperfusion Injury

Effective monitoring of cerebral ascorbate following intravenous antioxidant treatment is of great importance in evaluating the antioxidant efficiency for neuroprotection because ascorbate is closely related to a series of ischemia-induced neuropathological processes. This study demonstrates the validity of an online electrochemical system (OECS) for ascorbate detection as a platform for in vivo evaluation of neuroprotective efficiency of antioxidants by studying the dynamic change of hippocampal ascorbate during the acute period of cerebral ischemia and its responses to intravenous administration of antioxidants including ascorbate and glutathione (GSH). The OECS consists of a selective electrochemical detector made of a thin-layer electrochemical flow cell integrated with in vivo microdialysis. With such a system, the basal level of hippocampal ascorbate is determined to be 5.18 ± 0.60 μM (n = 20). This level is increased by 10 min of two-vessel occlusion (2-VO) ischemia treatment and reaches 11.51 ± 3.43 μM (n = 5) at the time point of 60 min after the ischemia. The 2-VO ischemia-induced hippocampal ascorbate increase is obviously attenuated by immediate intravenous administration of ascorbate (2.94 g/kg) or glutathione (5.12 g/kg) within 10 min after ischemia and the ascorbate level remains to be 3.75 ± 1.66 μM (n = 4) and 5.30 ± 0.79 μM (n = 5), respectively, at the time point of 60 min after ischemia. To confirm if the attenuated hippocampal ascorbate increase is attributed to the antioxidant-induced oxidative stress alleviation, we further study the immunoreactivity of 8-hydroxy-2-deoxyguanosine (8-OHdG) in the ischemic hippocampus and find that the 8-OHdG immunoreactivity is decreased by the administration of ascorbate or GSH as compared to the ischemic brain without antioxidant treatment. These results substantially demonstrate that the OECS for ascorbate detection could be potentially used as a platform for evaluating the efficiency of antioxidant neuroprotection in cerebral ischemia treatment.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Drug Evaluation, Preclinical; Electrochemistry; Hippocampus; Male; Neuroprotective Agents; Online Systems; Rats; Rats, Sprague-Dawley

Direct determination of cerebral metal ions in small volume biological samples is still the bottleneck for evaluating the roles that metal ions play in the physiological and pathological processes. In this work, selected copper ion (Cu(2+)) as a model, a facile and direct electrochemical method for detection of Cu(2+) has been developed on the basis of two new designed strategies: one is specific recognition molecule for Cu(2+)-AE-TPEA (N-(2-aminoethyl)-N,N',N'-tris(pyridine-2-yl-methyl)ethane-1,2-diamine); another is carbon dots (C-Dots) with high electrocatalytic activity. Based on the high affinity between TPEA and Cu(2+), the electrode assembled with C-Dot-TPEA hybridized nanocomposites shows high selectivity toward Cu(2+) over other metal ions, amino acids, and biological coexisting species, such as uric acid (UA), ascorbic acid (AA), and so on, which makes it possible to be used for determination of Cu(2+) in the complex brain system. By taking advantage of C-Dots, a dynamic linear range from 1 μM to 60 μM is first achieved with a detection limit of ∼100 nM in aCSF solution. In addition, the developed method with theoretical simplicity and less instrumental demands exhibits long-term stability and good reproducibility. As a result, the present strategy has been successfully applied in detection of cerebral Cu(2+) in normal rat brain and that followed by global cerebral ischemia, combined with in vivo microdialysis. The determined concentrations of Cu(2+) in the rat brain microdialysates by the present method are found to be identical to those obtained by the conventional ICP-AES method.

Topics: Amino Acids; Animals; Ascorbic Acid; Brain Ischemia; Carbon; Cerebral Cortex; Copper; Electrochemical Techniques; Electrodes; Ethylenediamines; Ions; Male; Nanocomposites; Pyridines; Rats; Rats, Sprague-Dawley; Surface Properties; Uric Acid

Ascorbic acid (AA) is a potent antioxidant, and its neuroprotective effect has not been established yet. Using the Rice-Vannucci model, we examined the effect of AA on hypoxic-ischemic (HI) injury in the immature rat brain. Under isoflurane anesthesia, 7-day-old rat pups received 750 mg/kg of AA by intraperitoneal injection just before hypoxic exposure; 8% oxygen for 90 min. Vehicle controls received an equal volume of saline. AA decreased a macroscopic brain injury score at 48 and 168 h post-HI compared with vehicle controls (48 h post-HI, AA 1.38+/-0.45 vs. controls 2.94+/-0.24, p<0.05; 168 h post-HI, 1.13+/-0.44 vs. 2.50+/-0.25, p<0.05). AA injection significantly decreased the number of both necrotic and apoptotic cells in cortex, caudate putamen, thalamus and hippocampus, and also seemed to reduce the number of TUNEL-positive cells. Western blot analysis showed that AA significantly suppressed 150/145 kDa subunits of alpha-fodrin breakdown products (FBDP) in cortex, striatum, thalamus and hippocampus at 24 and 48 h post-HI, and also 120 kDa subunit of FBDP in all examined regions except for thalamus, which indicated that AA injection inhibited both calpain and caspase-3 activation. Western blot analysis of nitrotyrosine failed to show inhibition of free radical production by AA, however, our results show that AA inhibits both necrotic and apoptotic cell death and that AA is neuroprotective after HI in immature rat brain.

Topics: Analysis of Variance; Animals; Animals, Newborn; Antioxidants; Apoptosis; Ascorbic Acid; Blotting, Western; Brain; Brain Ischemia; Calpain; Carrier Proteins; Caspase 3; Enzyme Activation; In Situ Nick-End Labeling; Microfilament Proteins; Microscopy, Electron; Necrosis; Neurons; Neuroprotective Agents; Rats; Tyrosine

The morphologic and functional outcomes of cerebral ischemia generally result from the acute neurochemical changes that occur 1 h after cerebral ischemia. As one of the small chemical species, ascorbic acid (AA) is involved in almost all kinds of neurochemical processes in acute cerebral ischemia. To understand the neurochemical processes in global cerebral ischemia, this study compares the dynamic regional changes of extracellular AA level, with in vivo microdialysis coupled with on-line electrochemical detection, in four different brain regions, 1 h after global cerebral ischemia induced by two-vessel occlusion (2-VO). The regional distribution of physiological AA levels in the microdialysates from striatum, cortex, dorsal hippocampus, and ventral hippocampus were 2.97 +/- 0.06, 3.98 +/- 0.09, 3.02 +/- 0.47, and 3.80 +/- 0.29 microM, respectively. In 1 h after 2-VO cerebral ischemia, the microdialysate AA levels in the above four regions varied in a different manner; the striatum AA slowly decreased to 86.49 +/- 5.53% of the basal level (n=3, P<0.05). The AA levels in the cortex, dorsal hippocampus, and ventral hippocampus increased to 549.80 +/- 167.86 % (n=3, P<0.05), 167.81 +/- 41.85 % (n=4, P<0.05) and 261.24 +/- 65.00% (n=3, P<0.05), in relation to their respective basal levels, respectively. The recorded spatiotemporal regional changes in the extracellular AA levels essentially reflect the intricate neurochemical changes during the acute period of global cerebral ischemia and may thus be useful for understanding the neurochemical processes of global cerebral ischemia.

Topics: Analysis of Variance; Animals; Ascorbic Acid; Brain; Brain Ischemia; Carotid Artery, Common; Catheterization; Electrochemical Techniques; Extracellular Space; Male; Microdialysis; Rats; Rats, Sprague-Dawley

Ischemic stroke results from brain blood vessel blockage by thrombus, and produces neuronal cell damage and death. While thrombolytic therapy with tPA has achieved some success in clinic, the strategy of using neuroprotective agents to treat ischemic stroke has been disappointing thus far. In the present work, we synthesized TBN, a derivative of the clinically useful stroke drug TMP armed with a powerful free radical-scavenging nitrone moiety. TBN retains the thrombolytic activity of the parent TMP and possesses strong antioxidative properties. TBN demonstrates significant activity in the rat MCAo stroke model. The results suggest that design of molecules possessing both thrombolytic and neuroprotective properties may be a novel strategy for effective stroke therapeutics.

Topics: Animals; Antioxidants; Brain Ischemia; Fibrinolytic Agents; Nitrogen Oxides; Pyrazines; Rats; Stroke; Thrombolytic Therapy

Experimental stroke studies indicate that oxidative stress is a major contributing factor to ischemic cerebral injury. Oxidative stress is also implicated in activation of matrix metalloproteinases (MMPs) and blood-brain barrier injury after ischemia-reperfusion. Plasma biomarkers of oxidative stress may have utility as early indicators of efficacy in Phase 2 trials of antioxidant therapies in human stroke. To date, a valid biomarker has been unavailable. We measured F2-isoprostanes (F2IPs), free-radical induced products of neuronal arachadonic acid peroxidation, in acute ischemic stroke. We aimed to determine the change in plasma F2IP levels over time and relationship with plasma MMP-9 in tPA-treated and tPA-untreated stroke patients.. We performed a case-control study of consecutive ischemic stroke patients (25 tPA-treated and 27 tPA-untreated) presenting within 8 hours of stroke onset. Controls were individuals without prior stroke from a primary care clinic network serving the source population from which cases were derived. Infarct volume was determined on acute diffusion-weighted MRI (DWI) performed within 48 hours using a semi-automated computerized segmentation algorithm. Phlebotomy was performed at <8 hours, 24 hours, 2 to 5 days, and 4 to 6 weeks. F2IPs were measured by gas chromatography/mass spectrometry and MMP-9 by ELISA. Prestroke antioxidant dietary intake was measured by the 24-hour recall method.. In 52 cases and 27 controls, early (median 6 hours postonset) F2IPs were elevated in stroke cases compared with controls (medians 0. 041 versus 0.0295 pg/mL, P=0.012). No difference in F2IPSs was present at later time points. Early plasma F2IPs correlated with MMP-9 in all patients (P=0.01) and the tPA-treated subgroup (P=0.02). No correlation was found with NIHSS, DWI infarct volume, 90-day Rankin score, or C-reactive protein (P>0.05 for all).. In early human stroke we found evidence of increased oxidative stress and a relationship with MMP-9 expression, supporting findings from experimental studies.

Topics: Aged; Aged, 80 and over; alpha-Tocopherol; Antioxidants; Ascorbic Acid; Biomarkers; Brain Ischemia; Case-Control Studies; Cerebral Infarction; Diffusion Magnetic Resonance Imaging; F2-Isoprostanes; Female; Fibrinolytic Agents; Humans; Male; Matrix Metalloproteinase 9; Middle Aged; Oxidative Stress; Severity of Illness Index; Stroke; Tissue Plasminogen Activator; Treatment Outcome

Topics: Animals; Ascorbic Acid; Brain Ischemia; Glutamic Acid; Hippocampus; Male; Propofol; Rats; Rats, Wistar; Reperfusion Injury

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

Low molecular weight antioxidants (LMWA), which reflect tissue reducing power, are among the endogenous mechanisms for neutralizing reactive oxygen species (ROS). Ischemic preconditioning (IPC) was associated with decreased oxidative stress. We examined the effect of focal ischemia on LMWA and on prostaglandin E(2) (PGE(2), a product of arachidonic acid oxidation) in the brain, heart, liver, and lungs of rats subjected to 90 min of ischemia and in IPC rats subjected to similar insult.. Transient right middle cerebral artery occlusion (MCAO) was performed for 90 min and at 0, 5, 30, 60, or 240 min of reperfusion, LMWA and PGE(2) were evaluated by cyclic voltametry (CV) and radioimmunoassay, respectively. IPC was induced by 2 min of MCAO, 24 h prior to the major ischemic episode.. LMWA decreased at 5 min of reperfusion in the brain, heart, liver, and lung and rose 4 h later only in the brain. PGE(2) levels increased three to fivefold in all tissues examined. Surprisingly, in IPC rats a dramatic increase of LMWA occurred at 5 min of reperfusion in the brain and in the peripheral organs. Uric acid, but not ascorbic, is the major LMWA increased.. We propose that after ischemia, ROS rapidly consume the antioxidants reserves in the brain and also in peripheral organs, suggesting that the whole body is under oxidative stress. Moreover, part of the neuroprotection afforded by IPC is mediated by the brain's ability to mobilize antioxidants, especially uric acid, that attenuate the massive ROS-mediated oxidative stress.

Topics: Animals; Antioxidants; Arachidonic Acid; Ascorbic Acid; Brain; Brain Ischemia; Dinoprostone; Disease Models, Animal; Free Radicals; Ischemic Preconditioning; Liver; Lung; Male; Myocardium; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Up-Regulation; Uric Acid

The incidence of Alzheimer disease is increased following ischemic episodes, and we previously demonstrated that following chronic hypoxia (CH), amyloid beta (Abeta) peptide-mediated increases in voltage-gated L-type Ca(2+) channel activity contribute to the Ca(2+) dyshomeostasis seen in Alzheimer disease. Because in certain cell types mitochondria are responsible for detecting altered O(2) levels we examined the role of mitochondrial oxidant production in the regulation of recombinant Ca(2+) channel alpha(1C) subunits during CH and exposure to Abeta-(1-40). In wild-type (rho(+)) HEK 293 cells expressing recombinant L-type alpha(1C) subunits, Ca(2+) currents were enhanced by prolonged (24 h) exposure to either CH (6% O(2)) or Abeta-(1-40) (50 nm). By contrast the response to CH was absent in rho(0) cells in which the mitochondrial electron transport chain (ETC) was depleted following long term treatment with ethidium bromide or in rho(+) cells cultured in the presence of 1 microm rotenone. CH was mimicked in rho(0) cells by the exogenous production of O2(-.). by xanthine/xanthine oxidase. Furthermore Abeta-(1-40) enhanced currents in rho(0) cells to a degree similar to that seen in cells with an intact ETC. The antioxidants ascorbate (200 microm) and Trolox (500 microm) ablated the effect of CH in rho(+) cells but were without effect on Abeta-(1-40)-mediated augmentation of Ca(2+) current in rho(0) cells. Thus oxidant production in the mitochondrial ETC is a critical factor, acting upstream of amyloid beta peptide production in the up-regulation of Ca(2+) channels in response to CH.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Antioxidants; Ascorbic Acid; Biological Transport; Brain Ischemia; Calcium; Calcium Channels; Cell Line; Chromans; Electron Transport; Electrons; Electrophysiology; Ethidium; Humans; Hypoxia; Immunohistochemistry; Mitochondria; Neurodegenerative Diseases; Oxidants; Oxygen; Peptides; Reactive Oxygen Species; Rotenone; Superoxides; Transfection; Up-Regulation; Xanthine Oxidase

A multiple analysis of the cerebral oxidative stress was performed on a physiological model of dementia accomplished by three-vessel occlusion in aged rats. The forward rate constant of creatine kinase, k(for), was studied by saturation transfer (31)P magnetic resonance spectroscopy in adult and aged rat brain during chronic hypoperfusion. In addition, free radicals in aging rat brain homogenates before and/or after occlusion were investigated by spin-trapping electron paramagnetic resonance spectroscopy (EPR). Finally, biochemical measurements of oxidative phosphorylation parameters in the above physiological model were performed. The significant reduction of k(for) in rat brain compared to controls 2 and 10 weeks after occlusion indicates a disorder in brain energy metabolism. This result is consistent with the decrease of the coefficient of oxidative phosphorylation (ADP:O), and the oxidative phosphorylation rate measured in vitro on brain mitochondria. The EPR study showed a significant increase of the ascorbyl free radical concentration in this animal model. Application of alpha-phenyl-N-tert-butylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin traps revealed formation of highly reactive hydroxyl radical (.OH) trapped in DMSO as the .CH(3) adduct. It was concluded that the ascorbate as a major antioxidant in brain seems to be useful in monitoring chronic cerebral hypoperfusion.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Chronic Disease; Creatine Kinase; Cyclic N-Oxides; Dementia; Disease Models, Animal; Energy Metabolism; Free Radicals; Hydroxyl Radical; Male; Mitochondria; Molecular Conformation; Nitrogen Oxides; Oxidative Phosphorylation; Oxidative Stress; Rats; Rats, Wistar; Spin Trapping

Topics: Animals; Ascorbic Acid; Behavior, Animal; Brain; Brain Ischemia; Disease Models, Animal; Drug Combinations; Female; Hemodynamics; Laser-Doppler Flowmetry; Magnesium; Magnesium Compounds; Magnesium Deficiency; Male; Neuroprotective Agents; Rats; Sodium Chloride; Vitamin B 6

Diquertin was shown to diminish blood viscosity, to decrease the aggregation of erythrocytes, and to increase their deformability using a model of the high blood viscosity syndrome in vitro. A mixture of Diquertin with Ascorbic Acid was more effective in improving rheological indicators of blood, then either Diquertin or Tanakan. On a model of chronic brain ischemia, which is accompanied by significant deterioration of the rheological properties of blood, it was shown that a therapy with a mixture of Diquertin and Ascorbic Acid decreases the expression of the high blood viscosity syndrome.

Topics: Animals; Antioxidants; Ascorbic Acid; Blood Viscosity; Brain Ischemia; Drug Therapy, Combination; Erythrocyte Aggregation; Fibrinogen; Male; Phytotherapy; Quercetin; Rats; Rats, Wistar

Cerebral ischaemia-reperfusion injury is associated with the generation of reactive oxygen species during the early phases of reoxygenation. EPC-K1, a phosphate diester of vitamins C and E, has been reported to possess potent hydroxyl radical scavenging activity. This study was performed to investigate the effectiveness of EPC-K1 in attenuating cerebral ischaemia-reperfusion injury in a rat model of transient focal cerebral ischaemia.. We evaluated the efficacy of EPC-K1 by measuring the concentration of cerebral thiobarbituric acid reactive substances (TBARS), an indicator of the extent of lipid peroxidation by free radicals, and infarct size in rats subjected to one hour of cerebral ischaemia and 4, 24, or 72 hours of reperfusion.. EPC-K1 significantly reduced both the cerebral TBARS level and the infarct size in a rat model of transient focal cerebral ischaemia. These results indicate that EPC-K1 administration during the early stages of reperfusion ameliorates ischaemic brain injury by inhibiting lipid peroxidation.. This report is the first to describe the protective mechanism of EPC-K1 by measuring both the TBARS level and infarct size in a rat model of transient focal cerebral ischaemia, and may suggest a potential clinical approach for the treatment of ischaemic cerebrovascular disease.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Disease Models, Animal; Free Radicals; Lipid Peroxidation; Male; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Thiobarbituric Acid Reactive Substances; Vitamin E

In the Rotterdam Study, the authors investigated whether high intake of antioxidants from food is associated with the risk of stroke. Among 5,197 participants who were followed on average for 6.4 years, 227 ischemic strokes occurred. Higher intake of antioxidants was associated with a lower risk of stroke. The relationship was dose-dependent, significant for vitamin C, and most pronounced in smokers. These results agree with the view that high dietary intake of antioxidants, in particular vitamin C and--in smokers--vitamin E, reduces the risk of stroke.

Topics: Aged; Antioxidants; Ascorbic Acid; Brain Ischemia; Cohort Studies; Comorbidity; Diet; Female; Follow-Up Studies; Fruit; Humans; Male; Netherlands; Risk; Risk Reduction Behavior; Stroke; Vegetables; Vitamin E

Primary rat astrocyte cultures absorbed dehydroascorbic acid from the medium and reduced it to intracellular ascorbate. Uptake of dehydroascorbic acid (5-200 microM) was inhibited only partially by glucose (10 mM). The remaining glucose-insensitive component of dehydroascorbic acid uptake was inhibited reversibly by sulfinpyrazone (IC(50) = 80 microM). Dehydroascorbic acid uptake was not mediated by Na(+)-ascorbate cotransporters or volume-sensitive anion channels because it was neither Na(+)-dependent nor blocked by the channel antagonist, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. Oxidative stress, induced in astrocytes by the lipophilic radical generator tert-butyl hydroperoxide, decreased intracellular glutathione concentration and inhibited accumulation of intracellular ascorbate from dehydroascorbic acid. Subsequent administration of either the native antioxidant alpha-tocopherol (200 microM) or anesthetic concentrations of the antioxidant sedative propofol (1-8 microM, administered 30 min after tert-butyl hydroperoxide), did not change glutathione concentration but restored the ability of astrocytes to accumulate intracellular ascorbate from dehydroascorbic acid. These results are consistent with a novel mechanism of astrocytic ascorbate accumulation that is inhibited by lipophilic radicals and protected by lipophilic antioxidants such as propofol.

Topics: Animals; Animals, Newborn; Ascorbic Acid; Astrocytes; Biological Transport, Active; Brain; Brain Ischemia; Cells, Cultured; Dehydroascorbic Acid; Deoxyglucose; Down-Regulation; Free Radical Scavengers; Fructose; Glucose; Intracellular Fluid; Oxidative Stress; Phloretin; Propofol; Rats; Rats, Wistar; Sodium; Sulfinpyrazone; Uricosuric Agents

There are no prospective studies to determine whether plasma vitamin C modifies the risk of stroke among hypertensive and overweight individuals. We sought to examine whether plasma vitamin C modifies the association between overweight and hypertension and the risk of stroke in middle-aged men from eastern Finland.. We conducted a 10.4-year prospective population-based cohort study of 2419 randomly selected middle-aged men (42 to 60 years) with no history of stroke at baseline examination. A total of 120 men developed a stroke, of which 96 were ischemic and 24 hemorrhagic strokes.. Men with the lowest levels of plasma vitamin C (<28.4 micromol/L, lowest quarter) had a 2.4-fold (95% CI, 1.4 to 4.3; P=0.002) risk of any stroke compared with men with highest levels of plasma vitamin C (>64.96 micromol/L, highest quarter) after adjustment for age and examination months. An additional adjustment for body mass index, systolic blood pressure, smoking, alcohol consumption, serum total cholesterol, diabetes, and exercise-induced myocardial ischemia attenuated the association marginally (relative risk, 2.1; 95% CI, 1.2 to 3.8; P=0.01). Adjustment for prevalent coronary heart disease and atrial fibrillation did not attenuate the association any further. Furthermore, hypertensive men with the lowest vitamin C levels (<28.4 micromol/L) had a 2.6-fold risk (95% CI, 1.52 to 4.48; P<0.001), and overweight men (> or =25 kg/m2) with low plasma vitamin C had a 2.7-fold risk (95% CI, 1.48 to 4.90; P=0.001) for any stroke after adjustment for age, examination months, and other risk factors.. Low plasma vitamin C was associated with increased risk of stroke, especially among hypertensive and overweight men.

Topics: Adult; Ascorbic Acid; Body Mass Index; Brain Ischemia; Cerebral Hemorrhage; Cohort Studies; Demography; Finland; Follow-Up Studies; Humans; Hypertension; Male; Middle Aged; Obesity; Prospective Studies; Risk; Risk Assessment; Risk Factors; Stroke

An association between ischemic stroke and increased oxidative stress has been suggested from animal studies. However, there is a lack of evidence with respect to this association in humans. Here, the time course of plasma levels of six carotenoids, which are lipophilic micronutrients with antioxidant properties, as well as of malondialdehyde (MDA), a marker of lipid peroxidation, was followed in ischemic stroke patients. Plasma levels of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha- and beta-carotene, as well as MDA were measured by high-performance liquid chromatography in 28 subjects (19 men and nine women aged 76.9+/-8.7 years) with an acute ischemic stroke of recent onset (<24h) on admission, after 6 and 24 h, and on days 3, 5, and 7. Carotenoid and MDA levels in patients on admission were compared with those of age- and sex-matched controls. Plasma levels of lutein, lycopene, alpha- and beta-carotene were significantly lower and levels of MDA were significantly higher in patients in comparison with controls. Significantly higher levels of MDA and lower levels of lutein were found in patients with a poor early-outcome (functional decline) after ischemic stroke as compared to patients who remained functionally stable. These findings suggest that the majority of plasma carotenoids are lowered immediately after an ischemic stroke, perhaps as a result of increased oxidative stress, as indicated by a concomitant rise in MDA concentrations. Among the carotenoids, only lutein plasma changes are associated with a poor early-outcome.

Topics: Aged; Ascorbic Acid; beta Carotene; Brain Ischemia; Carotenoids; Chromatography, High Pressure Liquid; Disease Progression; Female; Humans; Lipid Peroxidation; Lutein; Lycopene; Male; Malondialdehyde; Oxidative Stress; Stroke; Vitamin A; Vitamin E; Xanthophylls; Zeaxanthins

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

In vivo microdialysis coupled with liquid chromatography was developed for the continuous monitoring of brain neurochemicals during cerebral ischemia in awake, free moving gerbils. The dead volume of the microdialysis system was estimated to be less than 30 microl. The detection limits of the present assay were 0.2 to 2.0 microM for analytes at a signal to noise ratio of five. To validate this assay, a focal cerebral ischemia was produced by occlusion of one common carotid artery for 60 min and then reperfusion for additional 3 h in awake gerbils. A microdialysis probe was inserted into the striatum of the gerbil. Dialysates were autoinjected and analyzed extracellular pyruvate, lactate, and ascorbic acid by liquid chromatography with a UV detector during cerebral ischemia. Significant changes of pyruvate and the lactate/pyruvate ratio were observed. Biphasic and dynamic changes in ascorbic acid and lactate were proposed to correlate a secondary damage. This assay can be used as a tool to study dynamic changes of brain neurochemicals in awake animals.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Gerbillinae; Lactic Acid; Microdialysis; Pyruvic Acid

The effects of the neuroprotective aminosteroid U74006F (tirilazad mesylate, Freedox) were monitored microdialytically in rat cortex during three 4h periods beginning immediately, 25h and 49h after permanent middle cerebral artery occlusion. Either U74006F or vehicle only was administered 15 min, 2h, 6h, 12h and 24h after operation. The dialysate was analysed for on-line pH, ascorbic acid, uric acid, glucose and lactate. The efficacy of post-ischaemic treatment was shown by: a) lesion volume 53h after operation was significantly smaller in U74006F-treated animals; b) microdialytic findings were very similar to those found previously with pre-ischaemic drug application (reduction in release of ascorbic acid, uric acid and lactate, increased pH); c) an effect of U74006F on lactate release could still be seen on days 2 and 3; and d) increases in uric acid on days 2 and 3, possibly reflecting delayed cell death, were smaller in aminosteroid treated animals.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Drug Evaluation, Preclinical; Free Radicals; Glucose; Infarction, Middle Cerebral Artery; Lactic Acid; Male; Microdialysis; Neuroprotective Agents; Pregnatrienes; Rats; Rats, Inbred SHR; Uric Acid

The effect of diethylmaleate administration on ascorbic acid release following cerebral ischemia was investigated in anesthetized rat brain cortex. Cerebral ischemia, induced by ligating bilateral common carotid arteries and unilateral middle cerebral artery, significantly increased the extracellular ascorbic acid levels. Diethylmaleate (4 mmoles/kg, i.p.), which has been shown in earlier studies to decrease the ischemia-induced glutamate release, significantly reduced the ischemia-induced ascorbic acid release. The ischemia-induced ascorbic acid release was unaffected by perfusing NMDA receptor antagonist MK 801 (75 microM). Additionally, elevated extracellular glutamate levels, achieved by either externally applied glutamate solutions or by perfusing L-trans-pyrrolidine-2,4-dicarboxylate (PDC) (31.4 mM and 15.7 mM) to inhibit the glutamate uptake transporter, also significantly increased the extracellular ascorbic acid levels. These results suggested that ascorbic acid release in cerebral ischemia might be related to the elevated extracellular glutamate levels, which occurs following cerebral ischemia.

Topics: Amino Acid Transport System X-AG; Anesthesia; Animals; Ascorbic Acid; Brain Chemistry; Brain Ischemia; Carrier Proteins; Cerebral Cortex; Dicarboxylic Acids; Dizocilpine Maleate; Excitatory Amino Acid Antagonists; Extracellular Space; Glutamate Plasma Membrane Transport Proteins; Glutamic Acid; Glutathione; Infarction, Middle Cerebral Artery; Male; Maleates; Microdialysis; Neurotransmitter Uptake Inhibitors; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Symporters

Apart from its physiological role as a major antioxidant, ascorbate is highly concentrated in neuropils and ascorbate-mediated protection from excitotoxins has been demonstrated in vitro. Therefore, extracellular release of ascorbate during the early stage of ischemia-reperfusion was measured using a microdialysis electrode technique. One or two probes of the microdialysis biosensor were inserted into the rat striatum. One probe (n=16) was perfused with phosphate-buffered saline (PBS) for continuous oxidative signal recording. A second electropolymerised probe inserted into the other side of the striatum was perfused with PBS containing ascorbate oxidase in six rats. Forebrain ischemia-reperfusion was performed for 10min, followed by reperfusion for 60min. Ascorbate increased transiently during ischemia, and markedly to a maximum of 247.5+/-55. 8 microM from the baseline of 68.5+/-25.3 microM after reperfusion. The marked increase of extracellular ascorbate may be a marker of the early stage of reperfusion.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Corpus Striatum; Electrochemistry; Extracellular Matrix; Male; Microdialysis; Prosencephalon; Rats; Rats, Wistar; Reperfusion Injury; Signal Processing, Computer-Assisted; Stereotaxic Techniques

Electron microscopy and electrophysiological studies revealed pronounced structural and functional changes in the brain cortex in rats with experimental cerebral ischemia. Repeated administration of diquertin and ascorbic acid significantly attenuates ischemic damage induced by circulatory disturbances.

Topics: Alpha Rhythm; Animals; Antioxidants; Ascorbic Acid; Beta Rhythm; Brain Ischemia; Cerebral Cortex; Parietal Lobe; Protective Agents; Quercetin; Rats; Rats, Wistar; Theta Rhythm

Rapid on-line microdialysis coupled with liquid chromatography was developed for the continuous monitoring of brain neurochemicals during cerebral ischemia. Isocratic separation of these analytes was achieved within 3 min, hence, over 80 analyses could be performed in a 4-h experiment. The dead volume of the microdialysis system was estimated to be less than 10 microl. The detection limits of the present assay, at a signal-to-noise ratio of five, were 2.0, 0.2 and 0.5 microM, for lactic acid, pyruvate and ascorbic acid, respectively. To validate this assay, a transient ischemia was produced by occlusion of two common carotid arteries for 10 min in an anesthetized gerbil. A microdialysis probe was inserted into the striatum of the gerbil to simultaneously monitor pyruvate, lactic acid and ascorbic acid during cerebral ischemia. Significant and dynamic changes in these analytes could be resolved in 3-min intervals. This rapid assay can be used as a tool to study dynamic changes in neurochemicals of the brain, such as during cerebral ischemia.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Extracellular Space; Gerbillinae; Lactic Acid; Microdialysis; Pyruvic Acid; Reproducibility of Results

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

Global cerebral ischemia leads morphologically to selective neuronal damage in the CA1 sector of the hippocampus and in the striatum and functionally to a deficit in spatial learning and memory in the water maze. The results of earlier studies which examined the relationship between neuronal damage and the deficits in the water maze were not clear cut. It has been observed, however, that neuroprotection reduces both the deficits in the water maze as well as the neuronal damage. The present study therefore approached the relationship between the neuronal damage and the deficits in water maze using pharmacological means. Global cerebral ischemia was induced in male Wistar rats by four-vessel occlusion for 20 min. Ischemic rats were treated with the N-methyl-D-aspartate receptor antagonist dextromethorphan, 50 mg/kg, with the calcium antagonist levemopamil, 30 mg/kg, with the radical scavenger EPC-K1, 10 mg/kg, or with solvent. Treatment with dextromethorphan or levemopamil reduced the deficit in spatial learning by limiting the increase in swim distance due to ischemia. Both substances also reduced the deficit in spatial memory by minimizing the ischemia-induced reduction in time spent in the quadrant of the former platform position during the probe trial. EPC-K1 had no influence on the ischemia-induced behavioural changes. Group comparisons demonstrated that the swim speed and the percentage of the swimming path along the sidewall were affected neither by ischemia nor by any of the treatments. Histological examination revealed neuronal damage in the hippocampus and in the striatum in all of the ischemic rats. Treatment with dextromethorphan or levemopamil reduced the hippocampal damage by 32% and 36%, respectively. In addition, dextromethorphan diminished the striatal damage about 78%. Correlation analysis demonstrated a correlation between the cumulative swim distance of all 20 escape trials and hippocampal damage (r = 0.65, P < 0.001) but not between swim distance and striatal damage (r = 0.14, P = 0.364). No correlation was found between quadrant time of the probe trial and either hippocampal damage (r = -0.21, P = 0.19) or striatal damage (r = -0.02, P = 0.889). The average percentage of the swimming path along the side wall related to the hippocampal damage (r = 0.28, P = 0.035) but not to the striatal damage (r = 0.05, P = 0.381). With respect to the average swim speed a correlation to striatal damage was observed (r = -0.69, P < 0.001) but not to hi

Topics: Animals; Antioxidants; Ascorbic Acid; Behavior, Animal; Brain Ischemia; Calcium Channel Blockers; Dextromethorphan; Male; Maze Learning; Memory; Neurons; Neuroprotective Agents; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Verapamil; Vitamin E

Free radical-mediated injury is implicated in hypoxic-ischemic encephalopathy observed in neonates. We investigated in utero free radical production and injury following hypoxia-ischemia to premature fetal brain utilizing a rabbit model of acute placental insufficiency. Pregnant rabbits at 29 days gestation were randomized to uterine ischemia for 50 minutes (min) (hypoxia) or nonischemic controls. Fetal brains were obtained immediately after ischemia for oxidative and acute-injury markers or 24 hours (h) post-ischemia for histopathology. Nitrotyrosine formation, a marker of NO-derived species such as peroxynitrite, was observed only in hypoxic brains. Hypoxia resulted in a significant increase in nitrogen oxides, lipid peroxidation, and protein oxidation, with a concomitant decrease in total antioxidant capacity, compared with controls. Peroxynitrite addition to brain homogenate increased nitrogen oxides linearly (1:1), although protein carbonyls were unchanged. Concomitantly, in vitro cortical and hippocampal cell viability and ATP levels decreased, with an increase in brain edema in hypoxic brains. Fetuses delivered 24 h post-ischemia had increased hippocampal nuclear karyorrhexis on histology compared with controls. Antioxidant administration (ascorbic acid and Trolox) intraperitoneally ameliorated changes in cellular viability and brain edema. Acute fetal hypoxia-ischemia without reoxygenation results in increased nitrogen and oxygen free radical production that may cause brain injury. The merits of the described model are discussed.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Brain Ischemia; Cell Death; Cell Survival; Chromans; Female; Free Radicals; Hypoxia, Brain; Nitrogen; Oxidative Stress; Pregnancy; Rabbits; Reactive Oxygen Species; Uterus

The purpose of the present study was to determine after what time period hydroxyl radical formation contributes most to ischemic brain damage in focal ischemia, using a hydroxyl radical scavenger, EPC-K1, L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyl-tridecyl)-2H-1-be nzopyran-6yl-hydrogen phosphate] potassium salt. Focal ischemia was produced by thrombotic occlusion of the left middle cerebral artery in rats. After evaluation of the pharmacokinetics of EPC-K in the brain tissue and plasma following 10 mg/kg intravenous bolus treatment of conscious rats, we investigated the neuroprotective effect of EPC-K1 in the middle cerebral artery occlusion model. A single intravenous bolus of EPC-K1 was given immediately, 3 or 6 h after ischemia, and cerebral brain damage was measured 24 h after ischemia. When EPC-K1 was injected 3 h after ischemia, a significant (P < 0.01) reduction of cerebral brain damage was observed. EPC-K1 delivered by intravenous infusion that started immediately after ischemia and lasted for 24 h, also significantly (P < 0.05) reduced brain damage, but the efficacy of the neuroprotective effect was the same as that of the 3 h after ischemia bolus treatment. These results may indicate that the period of hydroxyl radical formation most critical for ischemic brain damage is a few hours after the third hour following ischemia in this model.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Free Radical Scavengers; Hydroxyl Radical; Male; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Vitamin E

Brain ascorbate levels in young adult female rat are lower than those in males. Loss of ascorbate during ischemia is also less in females, suggesting lower oxidative stress. After ovariectomy, however, ischemia-induced loss equals that in males. In the present study, we determined ascorbate levels in maturing male and female rat brain to establish when the gender difference in content arises. We further investigated whether 17beta-estradiol and/or progesterone treatment modulate levels and ischemia-induced loss in ovariectomized females and compared these data with those from normal females in proestrus and estrus. Gender differences in brain ascorbate content were absent before puberty and persisted only in cortex in aging rats. Chronic estradiol treatment, whether alone or in combination with progesterone, prevented an ovariectomy-induced ascorbate increase in hippocampus and caused levels in cortex and cerebellum to fall below those of randomly sampled normal females. These same low levels were found during proestrus and estrus. Estradiol replacement after ovariectomy prevented enhanced ischemia-induced ascorbate loss in hippocampus, but not in cortex or cerebellum. Ischemia-induced losses in proestrus and estrus were similar to those in normal controls. Progesterone had little effect in any region. These data indicate that ascorbate content and redox balance in female brain are influenced postpubertally by estrogens in a region-selective manner.

Topics: Age Factors; Animals; Ascorbic Acid; Brain; Brain Ischemia; Drug Implants; Estradiol; Estrogens; Estrus; Female; Glutathione; Male; Proestrus; Progesterone; Rats; Rats, Long-Evans; Sex Factors

A large body of experimental research indicates that the generation of free radicals leading to oxidative stress plays a role in the pathogenesis of ischemic brain injury, but evidence in humans is limited. We examined plasma levels of lipid hydroperoxides (measured as cholesteryl ester hydroperoxides, CEOOH) and ascorbic acid in 32 patients with cortical stroke, as compared with 13 patients with lacunar infarct. Patients with cortical stroke had significantly increased levels of CEOOH, which peaked on Day 5 after the ictus. Small decreases in ascorbic acid concentrations were not significant. There was a significant positive correlation of CEOOH with the NIH stroke scale, and a significant negative correlation with the Glasgow coma scale. Concentrations of CEOOH were significantly higher in patients with total anterior cerebral syndrome as compared with patients with partial anterior cerebral syndrome or posterior cerebral syndrome. Stroke volumes computed from CT or MRI scans were significantly correlated with plasma CEOOH levels. These findings implicate oxidative stress in ischemic brain injury in humans and suggest that measurements of CEOOH in plasma may be useful both prognostically as well as in monitoring therapeutic interventions.

Topics: Aged; Ascorbic Acid; Brain Ischemia; Cerebrovascular Disorders; Cholesterol Esters; Female; Humans; Lipid Peroxides; Magnetic Resonance Imaging; Male; Tomography, X-Ray Computed

Temporary occlusion of major cerebral blood vessels occasionally becomes necessary during surgical procedures. Ascorbic acid (Vitamin C) is an important non-enzymatic scavenger of free radicals and its protective effect on the brain in permanent focal cerebral ischaemia has been proven in a primate model of focal cerebral ischaemia [16]. Additional damage caused by reperfusion of the infarcted area has been shown in the rat model [22]. This study was undertaken to study the efficacy of ascorbic acid in decreasing infarct size in ischaemic reperfused brain. Maccaca radiata monkeys in the treated group were given two grams of ascorbic acid, parentally immediately before clipping the middle cerebral artery and the control group was given placebo. Reperfusion was done after four hours. Mean infarct size in all the three brain slices in the ascorbic acid pretreated group was 7.3% +/- 2.7 and in the placebo group 22.1 +/- 6.7 under similar conditions. The mean infarct size in the ascorbic acid pretreated group of monkeys was significantly lower when compared with the placebo group (p = 0.0003).

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Cerebral Infarction; Macaca radiata; Male; Neuroprotective Agents; Premedication; Rats; Reperfusion Injury

Differential pulse voltammetry with treated carbon fibre micro-electrodes has been successfully employed in in vivo analysis of neurotransmitter release and metabolism. This methodology has been now applied to ex vivo preparations (brain slices) in order to study diverse neurotransmitter activities in various brain regions ipsilateral and controlateral to a middle cerebral artery (MCA) occlusion performed in anaesthetised adult male rats. Data demonstrated that significant changes of voltammetric ascorbic acid levels related to the ischaemic state were monitored within the ipsilateral to MCA occlusion frontal cortex, striatum, nucleus accumbens and hippocampus which were the brain area studied. Furthermore, it appeared that voltammetric catecholaminergic and 5-hydroxy indolaminergic values measured within the nucleus accumbens controlateral to MCA occlusion differ significantly from the results monitored with the same technique in brain slices obtained from sham rats. In various studies, the brain regions contralateral to MCA occlusion are generally considered as control areas, however, the present data suggest that the nucleus accumbens contralateral to the MCA occlusion side is specifically affected by the ischaemic state.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Catechols; Cerebral Arteries; Cerebral Cortex; Corpus Striatum; Electrochemistry; Functional Laterality; Hippocampus; In Vitro Techniques; Indoles; Male; Microelectrodes; Neuropeptides; Neurotransmitter Agents; Organ Specificity; Rats; Rats, Sprague-Dawley

In this experimental study is illustrated an original model of cerebral asymmetric ischemia and reperfusion in the rat, induced by unilaterally elevating ICP and clamping the corresponding common carotid artery, that allows a direct comparison of the two brain hemispheres, one normal and the other ischemic, of the same animal.. The experimental procedure consisted in grafting two screws through the skull on the right side of the sagittal suture, one of them being connected to a Queckenstedt manometer for monitoring ICP variations. A nitroprusside solution (1 mg/ml administered through the femoral vein at a flow rate of 0.103 ml/min) was infused to achieve a significant drop of MABP. At this time point, animals were subjected to 5 min of ischemia and 10 min of reperfusion induced by clamping and declamping the right common carotid artery. During the whole period of ischemia and reperfusion ICP and MABP were constantly monitored. In order to provide an outlook on the metabolic alterations of brain tissue occurring during ischemia and reperfusion phenomena, several biochemical parameters of cellular energy metabolism and of oxygen radical-induced membrane damage were determined by a sensitive and reproducible HPLC method on perchloric acid tissue extracts.. The validity of the present model was supported by the finding of significant intrahemispheric differences in the concentration of several compounds considered as biochemical markers of tissue injury, such as adenosine 5'-triphosphate catabolites and malondialdehyde, this last indicating the damaging action of oxygen free radicals on cell membrane phospholipids.

Topics: Animals; Ascorbic Acid; Blood Pressure; Brain Ischemia; Carotid Stenosis; Chromatography, High Pressure Liquid; Disease Models, Animal; Intracranial Pressure; Lipid Peroxidation; Male; Malondialdehyde; Neurons; Rats; Rats, Wistar; Reperfusion Injury; Reproducibility of Results; Sensitivity and Specificity

Oxygen radicals produced by activated neutrophils have been involved in brain injury during ischemia-reperfusion. Platelet-activating factor (PAF) is a candidate as one of the mediators of neutrophil activation during cerebral ischemia-reperfusion. Recent evidence indicates that PAF-induced neutrophil activation is mediated by thromboxane A2 (TXA2). To study the role of PAF and TXA2 in radical production during cerebral ischemia-reperfusion, we evaluated the effects of a PAF antagonist, Y-24180, and a TXA2 antagonist, S-1452, on radical formation in rats with 1 h middle cerebral artery (MCA) occlusion. In the present study, we employed a new electron spin resonance (ESR) method coupled with brain microdialysis. The method uses the endogenous ascorbyl radical (AR) concentration as a marker of oxygen radicals and requires no spin-trapping agents. In the vehicle controls, extracellular AR from the ischemic brain cortex decreased during MCA occlusion. Following reperfusion, AR significantly increased at 30 mm and 1 h, returned to near the basal levels at 2 h, and increased again at 24 h after reperfusion. In the rats treated with S-1452 or Y-24180, AR decreased during MCA occlusion to the same extent as in the vehicle control. However, pretreatment with Y-24180 or S-1452 significantly attenuated the increase in extracellular AR after reperfusion, while it exerted no effect on the changes in extracellular ascorbate or tissue pO2 throughout the experimental period. In conclusion, PAF and TXA2 might contribute to cerebral ischemia-reperfusion injury by increasing the generation of oxygen radicals.

Topics: Animals; Ascorbic Acid; Azepines; Brain; Brain Ischemia; Bridged Bicyclo Compounds; Dehydroascorbic Acid; Extracellular Space; Fatty Acids, Monounsaturated; Free Radicals; Male; Oxygen; Partial Pressure; Peroxidase; Platelet Activating Factor; Platelet Aggregation Inhibitors; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion; Thromboxane A2; Triazoles

Using microdialysis, levels of metabolites in the extracellular fluid of the cerebral cortex were monitored during neurovascular surgery (9 aneurysm and 5 extra-intracranial bypass operations). Our aim was to use microdialysis to detect any local ischemia which might be caused by brain retraction or temporary clipping. Parameters were therefore quantified whose levels in the dialysate are known to be influenced by ischemia (on-line pH, ascorbic acid, uric acid, glutathione, cysteine, glucose, lactate, glucose:lactate ratio). In the aneurysm series, on-line pH fell after introduction of the retractor, and in the majority of cases the other parameters also showed changes in accordance with ischemic conditions in the region of the probe. These changes disappeared at the end of retraction, or sometimes even before. During the bypass operations, there were no marked changes in on-line pH or in any of the measured parameters. However, in some of these patients values for the glucose:lactate ratio, ascorbic acid and uric acid lay outside the suggested basal levels for minimally disturbed cortex, indicating possible changes in metabolism caused by inadequate perfusion (carotid artery occlusion). We conclude that microdialysis is a sensitive method of detecting intraoperative changes in cerebral metabolism.

Topics: Ascorbic Acid; Biomarkers; Brain Ischemia; Carotid Artery Diseases; Carotid Artery, Internal; Cerebral Cortex; Cerebral Revascularization; Constriction; Cysteine; Energy Metabolism; Extracellular Space; Glucose; Glutathione; Humans; Hydrogen-Ion Concentration; Intracranial Aneurysm; Intraoperative Complications; Lactates; Microdialysis; Monitoring, Intraoperative; Sensitivity and Specificity; Subarachnoid Hemorrhage; Uric Acid

A number of in vitro studies or in vivo cortical microdialysis measurements have observed that changes in the levels of ascorbic acid (AA), uric acid (UA), tryptophan (TRY), indoles and other compounds may be biochemical markers of cerebral ischaemic damages following occlusion of the rat middle cerebral artery (MCAO). The aim of the present work was to study the influence of early ischaemia upon presynaptic and postsynaptic activities in the cerebral cortex of rats. These activities have been studied by means of electrophysiological and electro-biochemical (voltammetric) measurements performed concomitantly every 5 min and applied with the same biosensor. The biosensor was inserted in the cerebral cortex of anaesthetised adult male rats which were then submitted to focal ischaemia via MCAO. Since changes in electrophysiological activity are considered marker of rise of ischaemia, the choice of simultaneous electrophysiological and electrochemical (voltammetric) analysis could allow the observation of specific biochemical(s) correlation(s) with the initial phase of ischaemia. The data obtained indicated that electrophysiological and voltammetric changes can be monitored simultaneously in the same brain region (i.e. effected by MCAO) by means of a single biosensor with an improved time resolution when compared with previous biochemical in vivo studies. In addition, a high correlation was observed between MCAO reduced functional responses of the neurons monitored by electrophysiology and increased levels of AA measured by voltammetry. This original observation suggests that AA is a biochemical marker of the very early stages of focal ischaemia and could be a useful tool for the evaluation of initial ischaemic damage.

Topics: Animals; Ascorbic Acid; Biomarkers; Brain Ischemia; Male; Membrane Potentials; Rats; Rats, Sprague-Dawley

Oxidative stress, assessed by tissue ascorbate loss following ischemia, is greater in male than female rat brain. The factors mediating this gender difference are unclear. The goal of the present studies was to determine the influence of gonadal sex hormones on this difference. Three weeks prior to experiment, adult Long-Evans male and female rats were gonadectomized for comparison with controls. Ascorbate and glutathione levels were determined in brain and plasma under basal conditions and in brain after one-hour decapitation ischemia, using liquid chromatography with electrochemical detection. Basal ascorbate levels in brain were 6-9% higher in males than in females, whereas plasma levels were 100% higher in males. After gonadectomy, the gender difference in plasma ascorbate levels was lost, while the effect on basal brain levels depended upon region. Ischemia-induced losses in brain ascorbate were three-fold greater in control males compared to control females. Significant losses occurred in frontal cortex, hippocampus, and cerebellum in males during ischemia, whereas loss in females was significant in cerebellum only. After gonadectomy, increased ascorbate loss was seen in all female brain regions, indicating enhanced oxidative stress. This increase eliminated the gender difference in loss; male ascorbate loss was comparatively unaffected by gonadectomy. Glutathione levels and loss were unaffected by either gender or gonadectomy, indicating differences in regulation from that of ascorbate. These findings provide evidence for the hypothesis that protection against oxidative stress is afforded by ovarian sex hormones, thus decreasing the potential for oxidative cell damage in females compared to males.

Topics: Animals; Ascorbic Acid; Body Water; Brain; Brain Ischemia; Decerebrate State; Female; Glutathione; Male; Orchiectomy; Ovariectomy; Oxidative Stress; Rats; Rats, Inbred Strains; Sex Characteristics

A system for in vivo, automatic, continuous monitoring of organ extracellular ascorbic acid in anesthetized rat is described. This system involves microdialysis perfusion and a LC system equipped with an electrochemical detector. Microdialysate, eluted from a microdialysis probe implanted in the brain cortex or in the left ventricular myocardium of anesthetized rats was collected in the sample loop of an on-line injector for direct injection onto the LC system. This automated method provides a shortened sample processing time. This system was utilized to investigate the effect of cerebral ischemia on cortex extracellular ascorbic acid and the effect of myocardial ischemia on left ventricular myocardium extracellular ascorbic acid in anesthetized rats. Basal ascorbic acid concentrations in the cortex and left ventricular myocardium ranged from 9.7 to 15.4 microM (mean +/- S.D., 12.7 +/- 2.5 microM from the results of eight rats) and from 9.3 to 36.0 microM (mean +/- S.D., 24.3 +/- 8.9 microM from the results of twelve rats), respectively. Cerebral ischemia significantly elevated ascorbic acid levels in the cortex extracellular space, while myocardial ischemia did not significantly alter ascorbic acid levels in the left ventricular myocardium extracellular space.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Chromatography, Liquid; Extracellular Space; Female; Heart Ventricles; Male; Microdialysis; Myocardial Ischemia; Rats; Rats, Sprague-Dawley

Ascorbate and glutathione (GSH) are the primary water-soluble antioxidants in the CNS. Oxidative stress, sometimes indicated by loss of these antioxidants, has been linked to several clinical and experimental conditions, including cerebral ischemia. These conditions are also gender-linked, with greater incidence or severity in males than females. To test whether there are gender differences in oxidant/antioxidant regulation, we determined basal levels of ascorbate and GSH in rat brain and their loss after 1 h decapitation ischemia. We found that ascorbate levels in male rat brain were 7-10% higher than in females, depending on region, whereas GSH levels were gender-independent. Significant ascorbate loss (up to 12%) occurred in males during ischemia, with a regional pattern of cerebellum > hippocampus > prefrontal cortex. Loss of ascorbate in females was not significant in any region. By contrast, loss of GSH was significant in both males and females. Greater loss of GSH than ascorbate was in agreement with previous studies and was consistent with loss from enzymatic degradation, as well as oxidation. The significant gender difference in ascorbate loss, as a marker of oxidative stress, supports the hypothesis that inherent differences in oxidant/antioxidant regulation contribute to gender differences in response to ischemia and other pathological conditions.

Topics: Analysis of Variance; Animals; Antioxidants; Ascorbic Acid; Basal Metabolism; Brain; Brain Ischemia; Evaluation Studies as Topic; Female; Male; Rats; Sex Characteristics

We measured ascorbic acid (reduced and oxidized) in brain, CSF and blood, before, during and after cerebral ischemia in newborn piglets. Bilateral carotid ligation induced a 54% decrease in cerebral blood flow (p < 0.01) and a 43% decrease in the cerebral metabolic rate of oxygen (p < 0.01). After ischemia and reperfusion, we obtained a 60% decrease (p < 0.01) in total brain ascorbic acid content. CSF ascorbic acid increased during reperfusion: +60% at 30 min (p < 0.001) and +160% at 120 min (p < 0.05). Blood ascorbic acid content did not change. These changes and the absence of massive oxidation of ascorbic acid in brain tissue suggest release of ascorbic acid by the brain during ischemia.

Topics: Animals; Animals, Newborn; Ascorbic Acid; Brain; Brain Ischemia; Cerebrovascular Circulation; Disease Models, Animal; Swine

Effect of L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H -1- benzopyran-6yl-hydrogen phosphate] potassium salt (EPC-K1, CAS 127061-56-7), a diester of alpha-tocopherol and ascorbic acid, on transient cerebral ischemia was studied in Mongolian gerbils. Cerebral energy metabolism and intracellular pH (pHi) were estimated employing in vivo 31P nuclear magnetic resonance (NMR) spectroscopy. Intraperitoneal injection of EPC-K1 (5 or 10 mg/kg) prior to ischemia significantly ameliorated pHi reduction in a dose dependent manner during ischemia. After reperfusion, energy and pHi recoveries were significantly faster in the EPC-K1 groups than in the control group. EPC-K1 (10 mg/kg) significantly reduced the extent of cerebral edema. Moreover, administration of EPC-K1 immediately after reperfusion significantly shortened the consciousness recovery in a dose dependent manner. The results suggest that EPC-K1 may exert protective effects on ischemic brain and may have therapeutic value in ischemic stroke.

Topics: Animals; Ascorbic Acid; Brain Chemistry; Brain Edema; Brain Ischemia; Consciousness; Dose-Response Relationship, Drug; Energy Metabolism; Gerbillinae; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Male; Vitamin E

Neuronal cell damage following ischaemia is postulated to be due to free radical induced lipid peroxidation, and ascorbic acid is supposedly an important non-enzymatic scavenger of such free radicals. This study was undertaken to evaluate the protective effect of ascorbic acid on the brain in a primate model after focal cerebral ischemia. Consumption of ascorbic acid in the monkey brain following ischaemia and its effect on macroscopic infarct size as demonstrated by 2, 3, 5, Triphenyl tetrazolium chloride (TTC) staining were used as parameters. The monkeys in the treated group were given 1 gram ascorbic acid parenterally every day for six days. The mean level of total ascorbic acid in right basal ganglia was 35.1 +/- 4.2 micrograms/mg of protein in the treated group as opposed to 22.9 +/- 2.1 micrograms/mg of protein in the nontreated group both before ischaemia. After right middle cerebral artery occlusion to produce focal cerebral ischaemia, the total ascorbic acid in the right basal ganglia 2 hours post ischaemia was 13.3 +/- 3.1 micrograms/mg of protein in the treated group as opposed to 9 +/- 1.6 micrograms/mg of protein in the untreated group. The average consumption of total ascorbic acid was 21.8 micrograms/mg of protein in the treated group and 13.9 micrograms/mg of protein in the nontreated group. Macroscopic infarct size as determined by TTC staining in the right cerebral hemisphere was 11.7 +/- 6.9 in treated group whereas it was 24.4 +/- 4.4 (expressed as percentage of right hemisphere) in the non-treated group. There was significant reduction in the size of the infarct in the treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Ascorbic Acid; Basal Ganglia; Brain Ischemia; Cerebral Infarction; Female; Free Radicals; Lipid Peroxidation; Macaca radiata; Male; Mammillary Bodies; Optic Chiasm; Reactive Oxygen Species; Temporal Lobe

Superoxide dismutase is well known to act as an effective antioxidant enzyme against cellular damage caused by oxidative stresses including ischemia/reperfusion-induced cerebral injury. However, it is still controversial whether or not the activity of endogenous superoxide dismutase changes during cerebral ischemia and reperfusion. In order to elucidate this phenomenon, we assayed the superoxide dismutase activity in the cerebral tissues of gerbils using the chemiluminescence method with a Cypridina luciferin analog. This method was demonstrated to be a sensitive and specific assay for the enzymatic activity of superoxide dismutase in cerebral tissues, which was not subject to interference from proteins or ascorbate. After 3 h of focal and global ischemia, there were no changes in the cerebral tissue superoxide dismutase activities. After 24 h of reperfusion following 1 h of ischemia, the superoxide dismutase activity decreased only approx 20%, whereas the adenylate kinase activities, measured in the same cerebral tissues as those used for superoxide dismutase assay, started to decline 1 h after reperfusion commenced and were approx 50% of the control levels after 24 h. These results show that almost all the activity of endogenous superoxide dismutase is maintained and does not decrease significantly as a result of ischemia/reperfusion-induced cerebral injury.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Gerbillinae; Hot Temperature; Luminescent Measurements; Male; Nerve Tissue Proteins; Reperfusion Injury; Sensitivity and Specificity; Superoxide Dismutase

Topics: Ascorbic Acid; Asphyxia Neonatorum; Brain Ischemia; France; Hospitals, University; Humans; Infant, Newborn; Intensive Care Units, Neonatal; Lactates; Lactic Acid

To assess the comprehensiveness of Medline and Embase computer searches for controlled trials.. Comparison of articles found after an exhaustive search of the literature with the yield of a Medline or Embase search. This was performed for controlled clinical trials on the efficacy of three interventions: homoeopathy, ascorbic acid for common cold, and ginkgo biloba for intermittent claudication and cerebral insufficiency. The number of controlled trials found by exhaustive search of the literature was 107, 61 and 45, respectively.. For homoeopathy, ascorbic acid and ginkgo the proportion of all trials found by Medline was 17%, 36% and 31% respectively and for Embase 13%, 25% and 58% respectively. After checking of the references in the Medline articles 44%, 79% and 76% of all trials were identified. After checking of the references in the Embase articles 42%, 72% and 93% of all trials were identified. About 20% of the articles was not correctly indexed. Of the best trials 68%, 91% and 83% could be found with Medline and 55%, 82% and 92% of the best trials were identified through Embase.. For the topics mentioned, Medline and Embase searches are sufficient to get an impression of the evidence from controlled trials, but only if references in the articles are followed for further evidence. If one wants to get a more complete picture, additional search strategies make sense. Of course, this picture may be different for other topics.

Topics: Abstracting and Indexing; Ascorbic Acid; Brain Ischemia; Clinical Trials as Topic; Common Cold; Homeopathy; Humans; Information Systems; Intermittent Claudication; MEDLINE; Plants, Medicinal

Oxygen free radicals have been implicated in the pathogenesis of brain injury induced by ischemia/reperfusion. We studied the role of endogenous reduced glutathione (GSH) in brain infarction associated with focal cerebral ischemia caused by permanent ligation of the right middle cerebral artery (MCA) and the right common carotid artery (CCA) plus temporary occlusion of the left CCA. GSH levels in the ischemic side of cortex decreased with time after ischemia and preceded cortical infarction estimated by the staining of mitochondrial respiratory enzymes with 2,3,5-triphenyltetrazolium chloride. GSH levels in the contralateral cortex were unchanged through the experimental periods. The extent of decrease of GSH levels and the severity of infarction in the ischemic cortex at 24 h after ischemia depended on the duration of occlusion of the left CCA. Depletion of brain GSH with buthionine sulfoximine, a selective inhibitor for gamma-glutamylcysteine synthetase, exacerbated cortical infarction and edema after ischemia. These results suggest that the endogenous brain GSH is an important determinant in the defense mechanisms against lesion formation after ischemia and support the possible role of oxygen radicals in the pathogenesis of ischemic brain injury.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Buthionine Sulfoximine; Cerebral Infarction; Glutathione; Injections, Intraventricular; Male; Methionine Sulfoximine; Rats; Rats, Inbred Strains

Brain concentrations of the antioxidant vitamins C and E decreased following unilateral carotid occlusion and reperfusion for 2 or 24 h in gerbils. Administration of the 21-aminosteroid inhibitor of lipid peroxidation, tirilazad mesylate (U74006F), prevented the decrease in level of both of these vitamins following 2 h of reperfusion. After 24 h of reperfusion, however, alpha-tocopherol (vitamin E) continued to be protected, but ascorbic acid (vitamin C) showed a pronounced decrease in content. The changes in concentrations of these vitamins are consistent with U74006F acting to inhibit peroxidation in the CNS by scavenging of lipid peroxyl radicals and suggest that, in the presence of this agent, injury-induced depletion of ascorbic acid may occur without irreversible tissue damage.

Topics: Animals; Ascorbic Acid; Brain; Brain Chemistry; Brain Ischemia; Gerbillinae; Lipid Peroxides; Male; Pregnatrienes; Reperfusion Injury; Time Factors; Vitamin E

Extracellular concentrations of ascorbic acid, glutathione, cysteine, uric acid, tyrosine, and tryptophan were monitored using intracerebral microdialysis in the left frontoparietal cortex of spontaneous hypertensive rats before, and for 3 h after, either focal ischemia [left middle cerebral artery occlusion (MCAO)] or sham operation. The size of the ischemic area and the position of the microdialysis probe were checked using the enzyme histotopochemical acid phosphatase reaction. The probe was always located in the cortex inside the stained area. Ascorbic acid levels rose immediately after MCAO and remained at about 12-fold for 3 h. There was a transient release of glutathione during 1-1.5 h. Uric acid concentrations were also increased but the differences did not reach significance. The levels of the amino acids tyrosine and tryptophan increased steadily after MCAO. The increases in cysteine were variable but significant. In some experiments, the pH of the dialysate was measured online. The parameters ascorbic acid, glutathione, cysteine, and pH are suitable for the early detection of cortical ischemic events by microdialysis.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Cysteine; Dialysis; Extracellular Space; Glutathione; Male; Rats; Rats, Inbred SHR; Uric Acid

Ascorbic acid, cysteine, glutathione, uric acid, tyrosine and tryptophan were quantified in samples of frontoparietal cortex, striatum, hippocampus and cerebellum from both sides of rat brain 0.5 h, 4 h and 24 h after focal ischemia. Cysteine, tyrosine and tryptophan were increased in cortex and striatum at 0.5 h, returning afterwards to normal. Uric acid was increased, whereas ascorbic acid and glutathione were correspondingly decreased. Although changes can be explained primarily by energy failure they are also consistent with free radical activity during early stages of ischemia.

Topics: Amino Acids; Animals; Ascorbic Acid; Brain Chemistry; Brain Ischemia; Cerebral Arteries; Cysteine; Free Radical Scavengers; Glutathione; Male; Rats; Rats, Inbred SHR; Uric Acid

Influence of natrii hydroxybutyrate (100 mg/kg), ascorbate (100 mg/kg), cavinton (5 mg/kg), bemitil (50 mg/kg), ethomersol (50 mg/kg) on Hb-O2 affinity and cortex PO2 after both carotid artery occlusion in rats was investigated. Correlation (r-0.87; P less than 0.05) between lowering of Hb-O2 affinity and antihypoxic effect was demonstrated in the line of these drugs.

Topics: Acute Disease; Animals; Antioxidants; Ascorbic Acid; Benzimidazoles; Brain Ischemia; Drug Evaluation, Preclinical; Hemoglobins; Hypoxia, Brain; Oxygen; Rats; Sodium Oxybate; Vasodilator Agents; Vinca Alkaloids

The content of B6, PP and C vitamins was determined in the blood, CSF and urine in 64 patients with ischemic stroke during admission and on the 10-15 and 25-30 days of the disease. Patients with ischemic stroke show a marked deficit of the mentioned vitamins. When vitamins were not included in the complex treatment of stroke their deficit remained, though the general condition of the patients improved.

Topics: Acute Disease; Adult; Aged; Ascorbic Acid; Brain Ischemia; Female; Humans; Male; Middle Aged; Niacinamide; Pyridoxine; Seasons

To verify whether lipid peroxidation is associated with focal cerebral ischemia, a unilateral middle cerebral artery occlusion was carried out in rats. The concentrations of various endogenous antioxidants in the ischemic center were measured, including alpha-tocopherol and ubiquinones as lipid-soluble antioxidants and ascorbate as a water-soluble antioxidant. At 30 minutes after ischemia, alpha-tocopherol decreased to 79% of baseline, reduced ubiquinone-9 to 73%, ubiquinone-10 to 66%, and reduced ascorbate to 76%. Six hours after ischemia, alpha-tocopherol decreased to 63% and reached a plateau, whereas reduced ubiquinones and reduced ascorbate declined further to 16% and 10%, respectively, 12 hours after ischemia and then reached plateau levels. These results suggest functional and durational differences between antioxidants and lipid peroxidation in this ischemic model. Although the reciprocal increase in oxidized ubiquinones during ischemia was not observed, that of oxidized ascorbate was noted. The complementary antioxidant system between cytoplasmic and membranous components, the combination alpha-tocopherol/ascorbate, was estimated from the calculated consumption ratio of these antioxidants on the basis that the loss of these reduced antioxidants is due to neutralization of free radicals. This system is suggested to play an important role in the early ischemic period. Urate also increased during ischemia. The possible involvement of the xanthine-xanthine oxidase system in initiating free radical reactions in cerebral ischemia is also discussed.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Lipid Peroxides; Male; Rats; Rats, Inbred Strains; Ubiquinone; Uric Acid; Vitamin E

To verify the lipid peroxidation in the focal cerebral ischemia, the levels of alpha-tocopherol, ubiquinone and ascorbate were measured in the ischemic center in rats. The former two were endogeneous lipid soluble antioxidants and the last was a water soluble antioxidant. alpha-Tocopherol, reduced ubiquinone-9 and -10, and reduced ascorbate decreased to 79%, 73%, 66%, and 76% 0.5 hour after ischemia, respectively. alpha-Tocopherol decreased to 63% 6 hours after ischemia, and then reached a plateau, while reduced ubiquinones and reduced ascorbate declined further to 16% and 10% 12 hours after ischemia, respectively, and then reached plateau levels. These results suggest their functional and durational differences as antioxidants against lipid peroxidation in this ischemic model. Although the reciprocal increase in oxidized ubiquinones during ischemia was not observed, that in oxidized ascorbate was noted. The complementary antioxidant system between cytoplasmic and membranous components, the combination alpha-tocopherol/ascorbate, was estimated from the calculated consumption ratio of these antioxidants, assuming that the loss of these reduced antioxidants is due to neutralization of free radicals. This system was suggested to play an important role in an early ischemic period. Urate also markedly increased during ischemia. Therefore, xanthine oxidase activity was measured in rats both in normal brain and in ischemic brain induced by four-vessel occlusion method. In the control rat, the enzyme activity was 0.87 +/- 0.13 nmol/g wet brain/min at 25 degrees C (mean +/- S.D.): 92.4% was associated with the NAD-dependent dehydrogenase form and only 7.6% with the oxygen-dependent superoxide-producing oxidase form. However, the ratio of the latter form increased to 43.7% after 0.5 hour of global ischemia despite the same level in total xanthine oxidase activity. This result suggests the involvement of the oxygen free radicals generated from the xanthine oxidase pathway in the pathogenesis of the ischemic injury of the rat brain.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Ischemic Attack, Transient; Lipid Peroxidation; Male; Oxidation-Reduction; Rats; Rats, Inbred Strains; Ubiquinone; Vitamin E; Xanthine Oxidase

Thirty minutes of total cerebral ischemia (decapitation) decreased total glutathione (GSH + GSSG) by 7% but had no detectable effect on the concentration of oxidized glutathione (GSSG), reduced ascorbate, or total ascorbate, In a model of reversible, bilateral hemispheric ischemia (four-vessel occlusion) no changes in glutathione or ascorbate were detected after 30 min of ischemia. During 24 h of reperfusion following such an insult no detectable change in total ascorbate, reduced ascorbate, or oxidized glutathione was noted: however, total brain glutathione declined by 25%. The findings are discussed in relation to the hypothesis that the deleterious effects of ischemia are due to an increase in free radical production which in turn leads to increased lipid peroxidation.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Free Radicals; Glutathione; Male; Oxidation-Reduction; Perfusion; Rats