3-nitrotyrosine and Encephalitis

Microdose lithium is protective against Alzheimer's disease (AD), although the precise mechanisms through which its protective effects are conferred remain unclear.. To further examine the effects during the earliest stages of Aβ pathology, we evaluated whether NP03, a microdose lithium formulation, modulates Aβ-mediated oxidative damage and neuroinflammation when applied to a rat transgenic model of AD-like amyloidosis overexpressing amyloid precursor protein (APP).. McGill-R-Thy1-APP transgenic rats and wild-type littermates were treated with NP03 or vehicle formulation for 8 weeks beginning at 3 months of age - a phase preceding Aβ plaque deposition in the transgenic rats.. Oxidative and nitrosative stress markers, protein-bound 4-hydroxynonenal (HNE) and proteinresident 3-nitrotyrosine (3-NT), inflammatory cytokines production, as well as microglial recruitment towards Aβ-burdened neurons were assayed. NP03 significantly decreased cerebral HNE and 3-NT, and reduced production of pro-inflammatory cytokines in McGill-R-Thy1-APP transgenic rats. NP03 further reduced expression of microglia surface receptor Trem2 and led to a corresponding reduction in microglia recruitment towards Aβ-burdened neurons in the CA1 region of the hippocampus.. These results suggest that NP03 may function to slow the AD-like pathology in part by modifying oxidative/nitrosative damage and neuroinflammation, raising the possibility that low doses of microencapsulated lithium might be of therapeutic-preventive value during very early or preclinical AD.

Topics: Aldehydes; Alzheimer Disease; Amyloid beta-Protein Precursor; Amyloidosis; Animals; CA1 Region, Hippocampal; Cytokines; Disease Models, Animal; Encephalitis; Humans; Lithium; Mice, Transgenic; Mutation; Plaque, Amyloid; Rats; Tyrosine

Maternal cigarette smoke exposure (SE) during gestation can cause lifelong adverse effects in the offspring's brain. Several factors may contribute including inflammation, oxidative stress and hypoxia, whose changes in the developing brain are unknown. Female Balb/c mice were exposed to cigarette smoke prior to mating, during gestation and lactation. Male offspring were studied at postnatal day (P) 1, P20 and 13 weeks (W13). SE dams had reduced inflammatory mediators (IL-1β, IL-6 and toll like receptor (TLR)4 mRNA), antioxidant (manganese superoxide dismutase (MnSOD)), and increased mitochondrial activities (OXPHOS-I, III and V) and protein damage marker nitrotyrosine. Brain hypoxia-inducible factor (HIF)1α and its upstream signalling molecule early growth response factor (EGR)1 were not changed in the SE dams. In the SE offspring, brain IL-1R, IL-6 and TLR4 mRNA were increased at W13. The translocase of outer mitochondrial membrane, and MnSOD were reduced at W13 with higher nitrotyrosine staining. HIF-1α was also increased at W13, although EGR1 was only reduced at P1. In conclusion, maternal SE increased markers of hypoxia and oxidative stress with mitochondrial dysfunction and cell damage in both dams and offspring, and upregulated inflammatory markers in offspring, which may render SE dams and their offspring vulnerable to additional brain insults.

Topics: Animals; Antioxidants; Cytokines; Encephalitis; Female; Gene Expression Regulation; Male; Maternal Exposure; Mice; Mice, Inbred BALB C; Nicotiana; Oxidative Stress; Pregnancy; Prenatal Exposure Delayed Effects; Smoke; Toll-Like Receptor 4; Tyrosine

While free radicals and inflammation constitute major routes of neuronal injury occurring in amyotrophic lateral sclerosis (ALS), neither antioxidants nor non-steroidal anti-inflammatory drugs have shown significant efficacy in human clinical trials. We examined the possibility that concurrent blockade of free radicals and prostaglandin E(2) (PGE(2))-mediated inflammation might constitute a safe and effective therapeutic approach to ALS. We have developed 2-hydroxy-5-[2-(4-trifluoromethylphenyl)-ethylaminobenzoic acid] (AAD-2004) as a derivative of aspirin. AAD-2004 completely removed free radicals at 50 nM as a potent spin-trapping molecule and inhibited microsomal PGE(2) synthase-1 (mPGES-1) activity in response to both lipopolysaccharide-treated BV2 cell with IC(50) of 230 nM and recombinant human mPGES-1 protein with IC(50) of 249 nM in vitro. In superoxide dismutase 1(G93A) transgenic mouse model of ALS, AAD-2004 blocked free radical production, PGE(2) formation, and microglial activation in the spinal cords. As a consequence, AAD-2004 reduced autophagosome formation, axonopathy, and motor neuron degeneration, improving motor function and increasing life span. In these assays, AAD-2004 was superior to riluzole or ibuprofen. Gastric bleeding was not induced by AAD-2004 even at a dose 400-fold higher than that required to obtain maximal therapeutic efficacy in superoxide dismutase 1(G93A). Targeting both mPGES-1-mediated PGE(2) and free radicals may be a promising approach to reduce neurodegeneration in ALS and possibly other neurodegenerative diseases.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Amyotrophic Lateral Sclerosis; Analysis of Variance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Calcium-Binding Proteins; Cerebral Cortex; Deoxyguanosine; Dinoprostone; Disease Models, Animal; Encephalitis; Free Radical Scavengers; Free Radicals; Gene Expression Regulation; Humans; Ibuprofen; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microfilament Proteins; Microglia; Motor Neurons; Oxidative Stress; Riluzole; Spinal Cord; Sulfasalazine; Superoxide Dismutase; Tyrosine

Gaucher's disease, the most common lysosomal storage disorder, is caused by the defective activity of glucocerebrosidase, the lysosomal hydrolase that degrades glucosylceramide. The neuronopathic forms of Gaucher's disease are characterized by severe neuronal loss, astrocytosis and microglial proliferation, but the cellular and molecular pathways causing these changes are not known. In the current study, we delineate the role of neuroinflammation in the pathogenesis of neuronopathic Gaucher's disease and show significant changes in levels of inflammatory mediators in the brain of a neuronopathic Gaucher's disease mouse model. Levels of messenger RNA expression of interleukin -1β, tumour necrosis factor-α, tumour necrosis factor-α receptor, macrophage colony-stimulating factor and transforming growth factor-β were elevated by up to ∼30-fold, with the time-course of the increase correlating with the progression of disease severity. The most significant elevation was detected for the chemokines CCL2, CCL3 and CCL5. Blood-brain barrier disruption was also evident in mice with neuronopathic Gaucher's disease. Finally, extensive elevation of nitrotyrosine, a hallmark of peroxynitrite (ONOO(-)) formation, was observed, consistent with oxidative damage caused by macrophage/microglia activation. Together, our results suggest a cytotoxic role for activated microglia in neuronopathic Gaucher's disease. We suggest that once a critical threshold of glucosylceramide storage is reached in neurons, a signalling cascade is triggered that activates microglia, which in turn releases inflammatory cytokines that amplify the inflammatory response, contributing to neuronal death.

Topics: Animals; Animals, Newborn; Anti-Inflammatory Agents, Non-Steroidal; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Blood-Brain Barrier; Calcium-Binding Proteins; Cell Death; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Encephalitis; Endothelial Cells; Enzyme-Linked Immunosorbent Assay; Gaucher Disease; Gene Expression Regulation, Developmental; Glucosylceramidase; Ibuprofen; Immunoglobulin G; Intercellular Adhesion Molecule-1; Intermediate Filament Proteins; Magnetic Resonance Imaging; Mice; Mice, Transgenic; Microfilament Proteins; Microglia; Nerve Tissue Proteins; Nestin; Neurons; TATA Box; Tyrosine; Vascular Cell Adhesion Molecule-1

Parkinson's disease (PD) is a devastating neurodegenerative disorder characterized by progressive motor debilitation, which affects several million people worldwide. Recent evidence suggests that glial cell activation and its inflammatory response may contribute to the progressive degeneration of dopaminergic neurons in PD. Currently, there are no neuroprotective agents available that can effectively slow the disease progression. Herein, we evaluated the anti-inflammatory and antioxidant efficacy of diapocynin, an oxidative metabolite of the naturally occurring agent apocynin, in a pre-clinical 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD.. Both pre-treatment and post-treatment of diapocynin were tested in the MPTP mouse model of PD. Diapocynin was administered via oral gavage to MPTP-treated mice. Following the treatment, behavioral, neurochemical and immunohistological studies were performed. Neuroinflammatory markers, such as ionized calcium binding adaptor molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), gp91phox and inducible nitric oxide synthase (iNOS), were measured in the nigrostriatal system. Nigral tyrosine hydroxylase (TH)-positive neurons as well as oxidative markers 3-nitrotyrosine (3-NT), 4-hydroxynonenal (4-HNE) and striatal dopamine levels were quantified for assessment of the neuroprotective efficacy of diapocynin.. Oral administration of diapocynin significantly attenuated MPTP-induced microglial and astroglial cell activation in the substantia nigra (SN). MPTP-induced expression of gp91phox and iNOS activation in the glial cells of SN was also completely blocked by diapocynin. Notably, diapocynin markedly inhibited MPTP-induced oxidative markers including 3-NT and 4-HNE levels in the SN. Treatment with diapocynin also significantly improved locomotor activity, restored dopamine and its metabolites, and protected dopaminergic neurons and their nerve terminals in this pre-clinical model of PD. Importantly, diapocynin administered 3 days after initiation of the disease restored the neurochemical deficits. Diapocynin also halted the disease progression in a chronic mouse model of PD.. Collectively, these results demonstrate that diapocynin exhibits profound neuroprotective effects in a pre-clinical animal model of PD by attenuating oxidative damage and neuroinflammatory responses. These findings may have important translational implications for treating PD patients.

Topics: Acetophenones; Animals; Anti-Inflammatory Agents; Biphenyl Compounds; Chromatography, High Pressure Liquid; Corpus Striatum; Disease Models, Animal; Disease Progression; Dopamine; Dopaminergic Neurons; Dose-Response Relationship, Drug; Encephalitis; Fluoresceins; Male; Mass Spectrometry; Mice; Mice, Inbred C57BL; Motor Activity; MPTP Poisoning; NADPH Oxidases; Neuroglia; Neuroprotective Agents; Neurotransmitter Agents; Nitric Oxide Synthase Type II; Organic Chemicals; Tyrosine; Tyrosine 3-Monooxygenase

Trichloroethylene, a chlorinated solvent widely used as a degreasing agent, is a common environmental contaminant. Emerging evidence suggests that chronic exposure to trichloroethylene may contribute to the development of Parkinson's disease. The purpose of this study was to determine if selective loss of nigrostriatal dopaminergic neurons could be reproduced by systemic exposure of adult Fisher 344 rats to trichloroethylene. In our experiments, oral administration of trichloroethylene induced a significant loss of dopaminergic neurons in the substantia nigra pars compacta in a dose-dependent manner, whereas the number of both cholinergic and GABAergic neurons were not decreased in the striatum. There was a robust decline in striatal levels of 3, 4-dihydroxyphenylacetic acid without a significant depletion of striatal dopamine. Rats treated with trichloroethylene showed defects in rotarod behavior test. We also found a significantly reduced mitochondrial complex I activity with elevated oxidative stress markers and activated microglia in the nigral area. In addition, we observed intracellular alpha-synuclein accumulation in the dorsal motor nucleus of the vagus nerve, with some in nigral neurons, but little in neurons of cerebral cortex. Overall, our animal model exhibits some important features of Parkinsonism, and further supports that trichloroethylene may be an environmental risk factors for Parkinson's disease.

Topics: alpha-Synuclein; Animals; Caspase 3; CD11b Antigen; Choline O-Acetyltransferase; Chromatography, High Pressure Liquid; Disease Models, Animal; Dopamine; Dopamine and cAMP-Regulated Phosphoprotein 32; Dose-Response Relationship, Drug; Electrochemistry; Encephalitis; Gene Expression Regulation; Male; Mitochondria; Neurodegenerative Diseases; Oxidative Stress; Rats; Rats, Inbred F344; Rotarod Performance Test; Solvents; Substantia Nigra; Trichloroethylene; Tyrosine; Tyrosine 3-Monooxygenase

Inflammation induced by hypoxia-ischemia (HI) contributes to the development of injury in the newborn brain. In this study, we investigated the role of galectin-3, a novel inflammatory mediator, in the inflammatory response and development of brain injury in a mouse model for neonatal HI. Galectin-3 gene and protein expression was increased after injury and galectin-3 was located in activated microglia/macrophages. Galectin-3-deficient mice (gal3-/-) were protected from injury particularly in hippocampus and striatum. Microglia accumulation was increased in the gal3-/- mice but accompanied by decreased levels of total matrix metalloproteinase (MMP)-9 and nitrotyrosine. The protection and increase in microglial infiltration was more pronounced in male gal3-/- mice. Trophic factors and apoptotic markers did not significantly differ between groups. In conclusion, galectin-3 contributes to neonatal HI injury particularly in male mice. Our results indicate that galectin-3 exerts its effect by modulating the inflammatory response.

Topics: Animals; Animals, Newborn; Brain; Disease Models, Animal; Encephalitis; Female; Galectin 3; Gliosis; Hypoxia-Ischemia, Brain; Inflammation Mediators; Male; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Nerve Degeneration; Tyrosine

Intracerebral hemorrhage (ICH) remains a major medical problem and currently has no effective treatment. Hemorrhaged blood is highly toxic to the brain, and catabolism of the pro-oxidant heme, mainly released from hemoglobin, is critical for the resolution of hematoma after ICH. The degradation of the pro-oxidant heme is controlled by heme oxygenase (HO). We have previously reported a neuroprotective role for HO2 in early brain injury after ICH; however, in vivo data that specifically address the role of HO2 in brain edema and neuroinflammation after ICH are absent. Here, we tested the hypothesis that HO2 deletion would exacerbate ICH-induced brain edema, neuroinflammation, and oxidative damage. We subjected wild-type (WT) and HO2 knockout ((-/-)) mice to the collagenase-induced ICH model. Interestingly, HO2(-/-) mice had enhanced brain swelling and neuronal death, although HO2 deletion did not increase collagenase-induced bleeding; the exacerbation of brain injury in HO2(-/-) mice was also associated with increases in neutrophil infiltration, microglial/macrophage and astrocyte activation, DNA damage, peroxynitrite production, and cytochrome c immunoreactivity. In addition, we found that hemispheric enlargement was more sensitive than brain water content in the detection of subtle changes in brain edema formation in this model. Combined, these novel findings extend our previous observations and demonstrate that HO2 deficiency increases brain swelling, neuroinflammation, and oxidative damage. The results provide additional evidence that HO2 plays a critical protective role against ICH-induced early brain injury.

Topics: Analysis of Variance; Animals; Brain Edema; Calcium-Binding Proteins; Cerebral Hemorrhage; Cytochromes c; Disease Models, Animal; Encephalitis; Fluoresceins; Functional Laterality; Glial Fibrillary Acidic Protein; Granulocyte Colony-Stimulating Factor; Heme Oxygenase (Decyclizing); Interleukin-3; Mice; Mice, Inbred C57BL; Mice, Knockout; Microfilament Proteins; Nerve Degeneration; Organic Chemicals; Recombinant Fusion Proteins; Recombinant Proteins; Spectrophotometry; Time Factors; Tyrosine

Manganese superoxide dismutase (MnSOD) provides the first line of defense against superoxide generated in mitochondria. SOD competes with nitric oxide for reaction with superoxide and prevents generation of peroxynitrite, a potent oxidant that can modify proteins to form 3-nitrotyrosine. Thus, sufficient amounts of catalytically competent MnSOD are required to prevent mitochondrial damage. Increased nitrotyrosine immunoreactivity has been reported after traumatic brain injury (TBI); however, the specific protein targets containing modified tyrosine residues and functional consequence of this modification have not been identified. In this study, we show that MnSOD is a target of tyrosine nitration that is associated with a decrease in its enzymatic activity after TBI in mice. Similar findings were obtained in temporal lobe cortical samples obtained from TBI cases versus control patients who died of causes not related to CNS trauma. Increased nitrotyrosine immunoreactivity was detected at 2 h and 24 h versus 72 h after experimental TBI and co-localized with the neuronal marker NeuN. Inhibition and/or genetic deficiency of neuronal nitric oxide synthase (nNOS) but not endothelial nitric oxide synthase (eNOS) attenuated MnSOD nitration after TBI. At 24 h after TBI, there was predominantly polymorphonuclear leukocytes accumulation in mouse brain whereas macrophages were the predominant inflammatory cell type at 72 h after injury. However, a selective inhibitor or genetic deficiency of inducible nitric oxide synthase (iNOS) failed to affect MnSOD nitration. Nitration of MnSOD is a likely consequence of peroxynitrite within the intracellular milieu of neurons after TBI. Nitration and inactivation of MnSOD could lead to self-amplification of oxidative stress in the brain progressively enhancing peroxynitrite production and secondary damage.

Topics: Adolescent; Adult; Aged; Animals; Brain; Brain Injuries; Chemotaxis, Leukocyte; Encephalitis; Enzyme Activation; Enzyme Inhibitors; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Nerve Degeneration; Nitrates; Nitric Oxide Synthase Type I; Oxidative Stress; Peroxynitrous Acid; Superoxide Dismutase; Tyrosine

We previously demonstrated that fenofibrate, a peroxisome proliferator-activated receptor alpha (PPARalpha) agonist, reduced the neurological deficit, the edema and the cerebral lesion induced by traumatic brain injury (TBI). In order to elucidate these beneficial effects, in the present study, we investigated, in the same TBI model, fenofibrate's effects on the inflammation and oxidative stress. Male Sprague Dawley rats were randomized in four groups: non-operated, sham-operated, TBI + vehicle, TBI + fenofibrate. TBI was induced by lateral fluid percussion of the temporoparietal cortex. Rats were given fenofibrate (50 mg/kg) or its vehicle (water containing 0.2% methylcellulose), p.o. 1 and 6 h after brain injury. A neurological assessment was done 24 h after TBI, then rats were killed and the brain COX2, MMP9 expression, GSx, GSSG levels were determined. The same schedule of treatment was used to evaluate the effect of fenofibrate on immunohistochemistry of 3NT, 4HNE and iNOS at 24 h post-injury. Our results showed that fenofibrate promotes neurological recovery by exerting anti-inflammatory effect evidenced by a decrease in iNOS, COX2 and MMP9 expression. In addition, fenofibrate showed anti-oxidant effect demonstrated by a reduction of markers of oxidative stress: loss of glutathione, glutathione oxidation ratio, 3NT and 4HNE staining. Our data suggest that PPARalpha activation could mediate pleiotropic effects and strengthen that it could be a promising therapeutic strategy for TBI.

Topics: Aldehydes; Animals; Anti-Inflammatory Agents; Antioxidants; Brain; Brain Injuries; Cyclooxygenase 2; Encephalitis; Fenofibrate; Glutathione; Male; Matrix Metalloproteinase 9; Nitric Oxide Synthase Type II; Oxidative Stress; PPAR alpha; Rats; Rats, Sprague-Dawley; Recovery of Function; Treatment Outcome; Tyrosine

S-100B is an astrocyte-derived protein that is increased in focal areas of the brain most severely affected by neuropathological changes in Alzheimer's disease (AD). Cell-based and clinical studies have implicated S-100B in progression of a pathologic, glial-mediated pro-inflammatory state in the CNS. However, the relationship between S-100B levels and susceptibility to AD-relevant neuroinflammation and neuronal dysfunction in vivo has not been determined. To test the hypothesis that overexpression of S-100B increases vulnerability to beta-amyloid (Abeta)-induced damage, we used S-100B-overexpressing transgenic (Tg) and S-100B knockout (KO) mice in a mouse model that involves intracerebroventricular infusion of human oligomeric Abeta1-42. This model mimics many features of AD, including robust neuroinflammation, Abeta plaques, synaptic damage and neuronal loss in the hippocampus. S-100B Tg, KO, and wild-type (WT) mice were infused with Abeta for 28 days, sacrificed at 60 days, and hippocampal endpoints analyzed. We found that Tg mice showed increased vulnerability to Abeta-induced neuropathology relative to either WT or KO mice. Specifically, Tg mice exhibited enhanced glial activation and neuroinflammation, increased nitrotyrosine staining (a marker of glial-induced neuronal damage), and more pronounced loss of synaptic markers. Interestingly, Tg mice showed no significant differences in Abeta plaque burden compared with WT or KO mice, suggesting that, as in the human situation, the severity of neuronal dysfunction did not correlate with amyloid deposition. Our data are consistent with a model in which S-100B overexpression in AD enhances glial activation and leads to an augmented neuroinflammatory process that increases the severity of neuropathologic sequelae.

Topics: Amyloid beta-Peptides; Animals; Biomarkers; Brain; Disease Models, Animal; Encephalitis; Genetic Predisposition to Disease; Gliosis; Humans; Injections, Intraventricular; Mice; Mice, Knockout; Mice, Transgenic; Nerve Degeneration; Nerve Growth Factors; Neurons; Peptide Fragments; Plaque, Amyloid; Presynaptic Terminals; S100 Calcium Binding Protein beta Subunit; S100 Proteins; Tyrosine

The potential utility of dietary supplementation in order to prevent some of the oxidative and inflammatory changes occurring in the brain with age, has been studied. The cerebral cortex of 27-month-old male B6C3F1 mice had elevated levels of nitric oxide synthase 1 (EC 1.14.13.39) (nNOS) and peptide nitrotyrosine relative to cortices of younger (4-month-old) animals. After 25-month-old mice received basal diet together with 300 mg/l acetyl L-carnitine in the drinking water for 8 weeks, these levels were fully restored to those found in younger animals. A partial restoration was found when old animals received basal diet supplemented with 200 ppm melatonin in the diet. Levels of mRNA (messenger RNA) for nNOS were unchanged following these treatments implying translational regulation of nNOS activity. Behavioral indices indicative of exploratory behavior were also depressed in aged animals. Dietary supplementation with melatonin or acetyl L-carnitine partially reversed these changes. These findings suggest that dietary supplementation cannot merely arrest but indeed reverse some age-related increases in markers of oxidative and inflammatory events occurring with the cortex.

Topics: Acetylcarnitine; Aging; Animals; Body Weight; Cerebral Cortex; Down-Regulation; Encephalitis; Exploratory Behavior; Male; Melatonin; Mice; Mice, Inbred Strains; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; RNA, Messenger; Tyrosine

Listeria monocytogenes (LM) is a Gram-positive facultative intracellular bacterium that causes fatal meningoencephalitis in humans and ruminants. A current paradigm predicts that intracellular bacteria are controlled by nitric oxide (NO) whose synthesis is catalyzed by inducible nitric oxide synthase (iNOS). The ability of macrophages (Mphi) to express iNOS shows extreme interspecies variability. Here the expression of iNOS and synthesis of NO was studied in listeric encephalitis of cattle, sheep, and goats. iNOS was expressed by a subset of Mphi in cerebral microabscesses in all three species. The level of iNOS expression and the density of cells per lesion expressing iNOS was highest in cattle, intermediate in sheep, and lowest in goats. The accumulation of nitrotyrosine (NT), an indicator of local NO synthesis, was observed in lesions of cattle but not in those of small ruminants. The density of iNOS-expressing cells in lesions was inversely correlated with the number of bacteria. No species differences were observed in regard to reactive oxygen intermediate (ROI) production by stimulated granulocytes, using the flow cytometric dihydrorhodamine-123 (DHR) method indicating ROI generation. Thus, the marked species differences in iNOS expression, NT accumulation, and LM content in lesions of ruminants with listeric encephalitis are explained by different amounts of ROI produced. It suggests that variations in the ability of Mphi to synthesize NO are of pathophysiological significance in listeriosis.

Topics: Animals; Brain; Cattle; Cattle Diseases; Colony Count, Microbial; Encephalitis; Goat Diseases; Goats; Immunohistochemistry; Listeria monocytogenes; Listeriosis; Macrophage Activation; Macrophages; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Reactive Oxygen Species; Retrospective Studies; Ruminants; Sheep; Sheep Diseases; Species Specificity; Tyrosine

Mild hypothermia is neuroprotective, but the reasons are not well known. Inflammation contributes to ischemic damage; therefore, we examined whether the protection by hypothermia may be attributable to alterations in the inflammation. We examined whether hypothermia might alter the inflammatory cell-associated inducible nitric oxide synthase (iNOS) and subsequent nitric oxide (NO) and peroxynitrite generation in experimental stroke and inflammation. Rats underwent 2 hr of middle cerebral artery occlusion (MCAO). Brain inflammation was modeled by intravenous lipopolysaccharide (LPS) (2 mg/kg) injection. Temperature was maintained at 33 degrees C for 2 hr immediately after MCAO and LPS injection, delayed 2 hr after MCAO or maintained at 38 degrees C. Cultured microglia were activated with LPS and then incubated at 33 or 37 degrees C. Both intraischemic and delayed mild hypothermia attenuated infarct size by 40% (p < 0.05). Immunohistochemistry was performed to identify cell type, iNOS, and peroxynitrite. The majority of iNOS- and peroxynitrite-positive cells were activated microglia-macrophages, and mild hypothermia significantly decreased the numbers of immunoreactive cells at 72 hr by >50% (p < 0.05). After ischemia, mild hypothermia decreased NO production by 40%. Similarly, hypothermia attenuated NO and iNOS in LPS-injected rats, as well as in cultured microglia. Aminoguanidine, an iNOS inhibitor, also attenuated infarct size and NO in ischemic and inflammation models. We conclude that mild hypothermia significantly inhibits the inflammatory response by affecting microglial iNOS-NO generation. Therapies directed against microglia or their activation may be useful in treating stroke.

Topics: Animals; Cells, Cultured; Disease Models, Animal; Encephalitis; Hypothermia, Induced; Infarction, Middle Cerebral Artery; Lipopolysaccharides; Male; Microglia; Monocytes; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Rats; Rats, Sprague-Dawley; Reactive Nitrogen Species; Stroke; Tyrosine

We examined the effects of interleukin-6 (IL-6) deficiency on brain inflammation and the accompanying bone marrow (BM) leukopoiesis and spleen immune reaction after systemic administration of a niacin antagonist, 6-aminonicotinamide (6-AN), which causes both astroglial degeneration/cell death in brain stem gray matter areas and BM toxicity. In both normal and genetically IL-6-deficient mice (IL-6 knockout (IL-6KO) mice), the extent of astroglial degeneration/cell death in the brain stem was similar as determined from disappearance of GFAP immunoreactivity. In 6-AN-injected normal mice reactive astrocytosis encircled gray matter areas containing astroglial degeneration/cell death, which were infiltrated by several macrophages and some T-lymphocytes. Reactive astrocytes and a few macrophages increased significantly the antioxidants metallothionein-I+II (MT-I+II) and moderately the MT-III isoform. In 6-AN-injected IL-6KO mice reactive astrocytosis and recruitment of macrophages and T-lymphocytes were clearly reduced, as were BM leukopoiesis and spleen immune reaction. Expression of MT-I+II was significantly reduced while MT-III was increased. Oxidative stress, as determined by measuring nitrated tyrosine and malondialdehyde, was increased by 6-AN to a greater extent in IL-6KO mice. The blood-brain barrier to albumin was only disrupted in 6-AN-injected normal mice, which likely is due to the substantial migration of blood-derived inflammatory cells into the CNS. The present results demonstrate that inflammation in CNS is clearly reduced during IL-6 deficiency and this effect is likely due to significant inhibition of BM leukopoiesis. We also show that IL-6 deficiency reduces the levels of neuroprotective antioxidants MT-I+II followed by an increased oxidative stress during CNS inflammation.

Topics: 6-Aminonicotinamide; Animals; Antigens, Differentiation; Astrocytes; Blood-Brain Barrier; Bone Marrow Cells; Brain Stem; Encephalitis; Glial Fibrillary Acidic Protein; Hematopoiesis; Immunohistochemistry; Interleukin-6; Macrophages; Malondialdehyde; Metallothionein; Metallothionein 3; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Nerve Tissue Proteins; Oxidative Stress; Protein Isoforms; Serum Albumin; T-Lymphocytes; Tyrosine

Poly(ADP-ribose) synthase (PARS), an abundant nuclear protein, has been described as an important candidate for mediation of neurotoxicity by nitric oxide. However, in cerebral ischemia, excessive PARS activation may lead to energy depletion and exacerbation of neuronal damage. We examined the effect of inhibiting PARS on the (a) degree of cerebral injury, (b) process of inflammatory responses, and (c) functional outcomes in a neonatal rat model of focal ischemia. We demonstrate that administration of 3-aminobenzamide, a PARS inhibitor, leads to a significant reduction of infarct volume: 63 +/- 2 (untreated) versus 28 +/- 4 mm(3) (treated). The neuroprotective effects currently observed 48 h postischemia hold up at 7 and 17 days of survival time and attenuate neurological dysfunction. Inhibition of PARS activity, demonstrated by a reduction in poly(ADP-ribose) polymer formation, also reduces neutrophil recruitment and levels of nitrotyrosine, an indicator of peroxynitrite generation. Taken together, our results demonstrate that PARS inhibition reduces ischemic damage and local inflammation associated with reperfusion and may be of interest for the treatment of neonatal stroke.

Topics: Animals; Animals, Newborn; Benzamides; Brain Ischemia; Cell Death; Cerebral Infarction; Encephalitis; Female; Male; Motor Activity; Neurologic Examination; Neuroprotective Agents; Neutrophils; Nitrates; Poly(ADP-ribose) Polymerase Inhibitors; Polymers; Rats; Rats, Wistar; Reperfusion Injury; Signal Transduction; Stroke; Time Factors; Tyrosine