3-nitrotyrosine and Carbon-Monoxide-Poisoning

Methane has been reported to play a protective role in ischemia-reperfusion injury via anti-oxidation, anti-inflammatory and anti-apoptotic activities. This study was designed to determine the protective effects of methane-rich saline (MRS) on acute carbon monoxide (CO) poisoning.. A total of 36 male Sprague-Dawley rats were randomly divided into 3 groups: sham group, CO group and MRS group. Acute CO poisoning was induced by exposing rats to 1000ppm CO in air for 40min and then to 3000ppm CO for an additional 20min until they lost consciousness. MRS at 10ml/kg was intraperitoneally administered at 0h, 8h and 16h after CO exposure. Rats were sacrificed 24h after CO exposure. Brains were collected for Nissl staining. The cortex and hippocampus were separated for the detections of malondialdehyde (MDA), 3-nitrotyrosine (3-NT), 8-hydroxydeoxyguanosine (8-OHdG), tumor necrosis factor-α (TNF-α), interleukin1-β (IL-1β), interleukin-6 (IL-6) and superoxide dismutase (SOD) activities.. The results showed that MRS treatment improved neuronal injury, reduced MDA, 3-NT and 8-OHdG, and increased SOD activity of the hippocampus and cortex compared with normal saline-treated rats. In addition, MRS reduced the expression of TNF-α and IL-1β in the brain but had no effect on IL-6 expression.. These findings suggest that MRS may protect the brain against acute CO poisoning-induced injury via its anti-oxidative and anti-inflammatory activities.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Analysis of Variance; Animals; Carbon Monoxide Poisoning; Carboxyhemoglobin; Cell Count; Cytokines; Deoxyguanosine; Disease Models, Animal; Hippocampus; Male; Malondialdehyde; Methane; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; RNA, Messenger; Sodium Chloride; Superoxide Dismutase; Time Factors; Tyrosine

The present study was designed to test the hypothesis that chronic very mild prenatal carbon monoxide (CO) exposure (25 parts per million) subverts the normal development of the rat cerebellar cortex. Studies at this chronic low CO exposure over the earliest periods of mammalian development have not been performed to date. Pregnant rats were exposed chronically to CO from gestational day E5 to E20. In the postnatal period, rat pups were grouped as follows: Group A: prenatal exposure to CO only; group B: prenatal exposure to CO then exposed to CO from postnatal day 5 (P5) to P20; group C: postnatal exposure only, from P5 to P20, and group D, controls (air without CO). At P20, immunocytochemical analyses of oxidative stress markers, and structural and functional proteins were assessed in the cerebellar cortex of the four groups. Quantitative real time PCR assays were performed for inducible (iNOS), neuronal (nNOS), and endothelial (eNOS) nitric oxide synthases.. Superoxide dismutase-1 (SOD1), SOD2, and hemeoxygenase-1 (HO-1) immunoreactivity increased in cells of the cerebellar cortex of CO-exposed pups. INOS and nitrotyrosine immunoreactivity also increased in blood vessels and Purkinje cells (PCs) of pups from group-A, B and C. By contrast, nNOS immunoreactivity decreased in PCs from group-B. Endothelial NOS immunoreactivity showed no changes in any CO-exposed group. The mRNA levels for iNOS were significantly up-regulated in the cerebellum of rats from group B; however, mRNA levels for nNOS and eNOS remained relatively unchanged in groups A, B and C. Ferritin-H immunoreactivity increased in group-B. Immunocytochemistry for neurofilaments (structural protein), synapsin-1 (functional protein), and glutamic acid decarboxylase (the enzyme responsible for the synthesis of the inhibitory neurotransmitter GABA), were decreased in groups A and B. Immunoreactivity for two calcium binding proteins, parvalbumin and calbindin, remained unchanged. The immunoreactivity of the astrocytic marker GFAP increased after prenatal exposure.. We conclude that exogenously supplied CO during the prenatal period promotes oxidative stress as indicated by the up-regulation of SOD-1, SOD-2, HO-1, Ferritin-H, and iNOS with increased nitrotyrosine in the rat cerebella suggesting that deleterious and protective mechanisms were activated. These changes correlate with reductions of proteins important to cerebellar function: pre-synaptic terminals proteins (synapsin-1), proteins for the maintenance of neuronal size, shape and axonal quality (neurofilaments) and protein involved in GABAergic neurotransmission (GAD). Increased GFAP immunoreactivity after prenatal CO-exposure suggests a glial mediated response to the constant presence of CO. There were differential responses to prenatal vs. postnatal CO exposure: Prenatal exposure seems to be more damaging; a feature exemplified by the persistence of markers indicating oxidative stress in pups at P20, following prenatal only CO-exposure. The continuation of this cellular environment up to day 20 after CO exposure suggests the condition is chronic. Postnatal exposure without prenatal exposure shows the least impact, whereas prenatal followed by postnatal exposure exhibits the most pronounced outcome among the groups.

Topics: Animals; Animals, Newborn; Apoferritins; Carbon Monoxide Poisoning; Cerebellum; Disease Models, Animal; Embryo, Mammalian; Female; Heme Oxygenase-1; Male; Nerve Tissue Proteins; Neurons; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Oxidative Stress; Pregnancy; Prenatal Exposure Delayed Effects; Rats; RNA, Messenger; Superoxide Dismutase; Superoxide Dismutase-1; Tyrosine

We measured changes in nitric oxide (NO) concentration in the cerebral cortex during experimental carbon monoxide (CO) poisoning and assessed the role for N-methyl-d-aspartate receptors (NMDARs), a glutamate receptor subtype, with progression of CO-mediated oxidative stress. Using microelectrodes, NO concentration was found to nearly double to 280 nM due to CO exposure, and elevations in cerebral blood flow, monitored as laser Doppler flow (LDF), were found to loosely correlate with NO concentration. Neuronal nitric oxide synthase (nNOS) activity was the cause of the NO elevation based on the effects of specific NOS inhibitors and observations in nNOS knockout mice. Activation of nNOS was inhibited by the NMDARs inhibitor, MK 801, and by the calcium channel blocker, nimodipine, thus demonstrating a link to excitatory amino acids. Cortical cyclic GMP concentration was increased due to CO poisoning and shown to be related to NO, versus CO, mediated guanylate cyclase activation. Elevations of NO were inhibited when rats were infused with superoxide dismutase and in rats depleted of platelets or neutrophils. When injected with MK 801 or 7-nitroindazole, a selective nNOS inhibitor, rats did not exhibit CO-mediated nitrotyrosine formation, myeloperoxidase (MPO) elevation (indicative of neutrophil sequestration), or impaired learning. Similarly, whereas CO-poisoned wild-type mice exhibited elevations in nitrotyrosine and myeloperoxidase, these changes did not occur in nNOS knockout mice. We conclude that CO exposure initiates perivascular processes including oxidative stress that triggers activation of NMDA neuronal nNOS, and these events are necessary for the progression of CO-mediated neuropathology.

Topics: Animals; Brain Chemistry; Calcium Channel Blockers; Carbon Monoxide Poisoning; Cyclic GMP; Dizocilpine Maleate; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Indazoles; Laser-Doppler Flowmetry; Male; Maze Learning; Mice; Mice, Knockout; Microelectrodes; Neurons; Neurotoxicity Syndromes; Neutropenia; Neutrophils; NG-Nitroarginine Methyl Ester; Nimodipine; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Platelet Count; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Tyrosine

Studies were conducted with rats to investigate whether exposure to CO at concentrations frequently found in the environment caused nitric oxide (NO)-mediated vessel wall changes. Exposure to CO at concentrations of 50 parts per million or higher for 1 h increased the concentration of nitrotyrosine in the aorta. Immunologically reactive nitrotyrosine was localized in a discrete fashion along the endothelial lining, and this was inhibited by pretreatment with the NO synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME). The CO-induced elevations of aortic nitrotyrosine were not altered by neutropenia or thrombocytopenia, and CO caused no change in the concentration of endothelial NOS. Consequences from NO-derived stress on the vasculature included an enhanced transcapillary efflux of albumin within the first 3 h after CO exposure and leukocyte sequestration that became apparent 18 h after CO exposure. Oxidized plasma low-density lipoprotein was found immediately after CO exposure, but this was not inhibited by L-NAME pretreatment. We conclude that exposure to relatively low CO concentrations can alter vascular status by several mechanisms and that many changes are linked to NO-derived oxidants.

Topics: Animals; Aorta; Blood Platelets; Blood Vessels; Blotting, Western; Carbon Monoxide Poisoning; Carboxyhemoglobin; Cholesterol, Dietary; Endothelium, Vascular; Immunohistochemistry; Leukocytes; Male; Neutrophils; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Oxidants; Oxidative Stress; Rats; Rats, Wistar; Tyrosine

Nitric oxide is a short-lived free radical and physiological mediator which has the potential to cause cytotoxicity. Studies were conducted to investigate whether nitric oxide, and the potent oxidant peroxynitrite, were generated in brain during experimental carbon monoxide (CO) poisoning in the rat. Nitric oxide production was documented by electron paramagnetic resonance spectroscopy, and found to be increased by ninefold immediately after CO poisoning. Evidence that peroxynitrite was generated was sought by looking for nitrotyrosine in the brains of CO-poisoned rats. Nitrotyrosine was found deposited in vascular walls, and also diffusely throughout the parenchyma in inummocytochemical studies. The affinity and specificity of an anti-nitrotyrosine antibody was investigated and a solid phase immunoradiochemical assay was developed to quantity nitrotyrosine in brain homogenates. A 10-fold increase in nitrotyrosine was found in the brains of CO-poisoned rats. Platelets were involved with production of nitrotyrosine in the early phase of exposure to CO. However, nitrotyrosine formation and leukocyte sequestration were not decreased in thrombocytopenic rats poisoned with CO according to the standard model. When rats were pre-treated with the nitric oxide synthase inhibitor, L-nitroarginine methyl ester, formation of both nitric oxide and nitrotyrosine in response to CO poisoning were abolished, as well as leukocyte sequestration in the microvasculature, endothelial xanthine dehydrogenase conversion to xanthine oxidase, and brain lipid peroxidation. We conclude that perivascular reactions mediated by peroxynitrite are important in the cascade of events which lead to brain oxidative stress in CO poisoning.

Topics: Animals; Arginine; Blood Platelets; Brain; Carbon Monoxide Poisoning; Electron Spin Resonance Spectroscopy; Immunohistochemistry; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Rats; Rats, Wistar; Tyrosine