3-nitrotyrosine and Brain-Infarction

α-Synuclein (α-Syn), one of the most abundant proteins in the CNS, is known to be a major player in the neurodegeneration observed in Parkinson's disease. We currently report that transient focal ischemia upregulates α-Syn protein expression and nuclear translocation in neurons of the adult rodent brain. We further show that knockdown or knock-out of α-Syn significantly decreases the infarction and promotes better neurological recovery in rodents subjected to focal ischemia. Furthermore, α-Syn knockdown significantly reduced postischemic induction of phospho-Drp1, 3-nitrotyrosine, cleaved caspase-3, and LC-3 II/I, indicating its role in modulating mitochondrial fragmentation, oxidative stress, apoptosis, and autophagy, which are known to mediate poststroke neuronal death. Transient focal ischemia also significantly upregulated serine-129 (S129) phosphorylation (pα-Syn) of α-Syn and nuclear translocation of pα-Syn. Furthermore, knock-out mice that lack PLK2 (the predominant kinase that mediates S129 phosphorylation) showed better functional recovery and smaller infarcts when subjected to transient focal ischemia, indicating a detrimental role of S129 phosphorylation of α-Syn. In conclusion, our studies indicate that α-Syn is a potential therapeutic target to minimize poststroke brain damage.. Abnormal aggregation of α-synuclein (α-Syn) has been known to cause Parkinson's disease and other chronic synucleinopathies. However, even though α-Syn is linked to pathophysiological mechanisms similar to those that produce acute neurodenegerative disorders, such as stroke, the role of α-Syn in such disorder is not clear. We presently studied whether α-Syn mediates poststroke brain damage and more importantly whether preventing α-Syn expression is neuroprotective and leads to better physiological and functional outcome after stroke. Our study indicates that α-Syn is a potential therapeutic target for stroke therapy.

Topics: alpha-Synuclein; Animals; Brain Infarction; Brain Ischemia; Caspase 3; Death-Associated Protein Kinases; Disease Models, Animal; Gene Expression Regulation; Male; Mice; Mice, Transgenic; Microtubule-Associated Proteins; Motor Activity; PC12 Cells; Protein Serine-Threonine Kinases; Rats; Rats, Inbred SHR; RNA, Small Interfering; Stroke; Tyrosine

Traumatic brain injury (TBI) initiates a neuroinflammatory cascade that contributes to neuronal damage and behavioral impairment. Toll-like receptors (TLRs) are signaling receptors in the innate immune system, although emerging evidence indicates their role in brain injury. We have therefore investigated the role played by TLR4 signaling pathway in the development of mechanisms of secondary inflammatory process in traumatic brain injury (TBI) differ in mice that lack a functional TLR4 signaling pathway.. Controlled cortical impact injury was performed on TLR4 knockout (KO) mice (C57BL/10ScNJ) and wild-type (WT) mice (C57BL/10ScNJ). TBI outcome was evaluated by determination of infarct volume and assessment of neurological scores. Brains were collected at 24 h after TBI. When compared to WT mice, TLR4 KO mice had lower infarct volumes and better outcomes in neurological and behavioral tests (evaluated by EBST and rotarod test). Mice that lacked TLR4 had minor expression of TBI-induced GFAP, Chymase, Tryptase, IL-1β, iNOS, PARP and Nitrotyrosine mediators implicated in brain damage. The translocation of expression of p-JNK, IκB-α and NF-κB pathway were also lower in brains from TLR4 KO mice. When compared to WT mice, resulted in significant augmentation of all the above described parameters. In addition, apoptosis levels in TLR4 KO mice had minor expression of Bax while on the contrary with Bcl-2.. Our results clearly demonstrated that absence of TLR4 reduces the development of neuroinflammation, tissues injury events associated with brain trauma and may play a neuroprotective role in TBI in mice.

Topics: Animals; Brain Infarction; Brain Injuries; Cerebral Cortex; Gene Expression Regulation; Glial Fibrillary Acidic Protein; I-kappa B Proteins; Inflammation; Interleukin-1beta; MAP Kinase Kinase 4; Mice; Mice, Knockout; Nerve Tissue Proteins; NF-kappa B; NF-KappaB Inhibitor alpha; Nitric Oxide Synthase Type II; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Toll-Like Receptor 4; Tryptases; Tyrosine

The aim of the present study was to ascertain whether brain cooling causes attenuation of traumatic brain injury by reducing brain nitrostative and oxidative damage. Brain cooling was accomplished by infusion of 5 mL of 4°C saline over 5 minutes via the external jugular vein. Immediately after the onset of traumatic brain injury, rats were randomized into two groups and given 37°C or 4°C normal saline. Another group of rats were used as sham operated controls. Behavioral and biochemical assessments were conducted on 72 hours after brain injury or sham operation. As compared to those of the sham-operated controls, the 37°C saline-treated brain injured animals displayed motor deficits, higher cerebral contusion volume and incidence, higher oxidative damage (e.g., lower values of cerebral superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, but higher values of cerebral malondialdehyde), and higher nitrostative damage (e.g., higher values of neuronal nitric oxide synthase and 3-nitrotyrosine). All the motor deficits and brain nitrostative and oxidative damage were significantly reduced by retrograde perfusion of 4°C saline via the jugular vein. Our data suggest that brain cooling may improve the outcomes of traumatic brain injury in rats by reducing brain nitrostative and oxidative damage.

Topics: Animals; Body Temperature; Brain; Brain Infarction; Brain Injuries; Catalase; Glutathione Reductase; Hypothermia, Induced; Male; Malondialdehyde; Nitric Oxide Synthase Type II; Nitrosation; Oxidative Stress; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Tyrosine

The goal of our study was whether free radicals contribute to the pathogenesis of the lacunar stroke to investigate the day after hospitalization, the concentrations of 3-nitrotyrosine and tyrosine in the cerebrospinal fluid (CSF) from living patients. The subjects included 20 living patients with lacunar stroke and 20 controls. The NIH stroke scale score was used to assess the severity of the stroke, including that the patients were mild cases. There was no expansion of the infarct lesion in the brain, as assessed by CT on the day following admission. The concentration of 3-nitrotyrosine was significantly higher in patients with lacunar stroke. In contrast, the concentration of tyrosine did not differ between the two groups. Furthermore, the 3-nitrotyrosine/tyrosine ratio was significantly higher in patients with lacunar stroke than in controls. Our results show that free radicals are produced in the CSF of lacunar stroke patients and that nitration of neuronal proteines is enhanced under this condition. These obsetvations suggest that lacunar stroke patients should be treated with edaravon, which is a free radical scavenger usually prescribed for cases of major strokes, as it will likely improve the prognosis of these patients.

Topics: Aged; Brain Infarction; Cell Count; Female; Humans; Male; Middle Aged; Severity of Illness Index; Statistics, Nonparametric; Tyrosine

Peroxynitrite is responsible for nitration in vivo, whereas myeloperoxidase can also catalyze protein nitration in the presence of high NO2(-) levels. Recent reports of myeloperoxidase-mediated enzyme inactivation or lipid peroxidation have suggested a role of myeloperoxidase in various pathological conditions. To clarify the role of myeloperoxidase in ischemic brain injury, the authors measured nitrotyrosine formation and infarct volume in myeloperoxidase-deficient or wild-type mice subjected to 2-hour focal cerebral ischemia-reperfusion. Twenty-four hours after reperfusion, infarct volume was significantly larger in myeloperoxidase-deficient mice than in wild-type mice (81 +/- 20 mm(3) vs. 52 +/- 13 mm(3), P < 0.01), and nitrotyrosine levels in the infarct region were higher in myeloperoxidase-deficient mice than in wild-type mice (13.4 +/- 6.1 microg/mg vs. 9.8 +/- 4.4 microg/mg, P = 0.13). Fourteen hours after reperfusion, the nitrotyrosine level was significantly higher in myeloperoxidase-deficient mice than in wild-type mice (3.3 +/- 2.9 microg/mg vs. 1.4 +/- 0.4 microg/mg, P < 0.05). The authors conclude that the absence of myeloperoxidase increases ischemic neuronal damage in vivo, and that the myeloperoxidase-mediated pathway is not responsible for the nitration reaction in cerebral ischemia-reperfusion.

Topics: Animals; Brain; Brain Infarction; Female; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Peroxidase; Peroxynitrous Acid; Reperfusion Injury; Time Factors; Tyrosine