Involvement of SIRT1 and SIRT3 in Effects of Hypoxic Hypobaric Preconditioning on Hippocampal Damage Induced by Chronic Cerebral Hypoperfusion in C57/6j and a7nAchRs(-/-) Mice / Participación de SIRT1 y SIRT3 en los Efectos del Precondicionamiento Hipobárico Hipóxico sobre el Daño del Hipocampo Inducido por Hipoperfusión Cerebral Crónica en Ratones C57/6j y a7nAchRs (-/-)

SUMMARY: Hypoxic preconditioning is known to induce neuroprotection, but its effects and pathways in chronic brain pathology still unknown. The aim was to establish an involvement of a7 subunit of nicotinic acetylcholine receptors (a7nAchRs), and sirtuins of 1 (SIRT1) and 3 (SIRT3) types in the effects of hypoxic hypobaric preconditioning on brain damage in mice with chronic cerebral hypoperfusion caused by the left common carotid artery occlusion. The male C57/6j (C57, wild type) and a7nAchRs(-/-) mice were divided to six experimental groups (10 mice per group): sham-operated C57, C57 with chronic cerebral hypoperfusion, C57 with hypoxic hypobaric preconditioning and chronic cerebral hypoperfusion, sham-operated a7nAchRs(-/-) mice, a7nAchRs(-/-) with chronic cerebral hypoperfusion, a7nAchRs(-/-) with hypoxic hypobaric preconditioning and chronic cerebral hypoperfusion. For preconditioning, mice were exposed to hypoxia by "lifting" in barochamber to simulated altitude of 5600 m a.s.l. for 1 h/day on 3 consecutive days before surgical manipulation. Expressions of SIRT1, SIRT3 in brain tissue, and histopathological changes of the hippocampi were examined. It was shown that 8-week chronic hypoperfusion of the brain, caused by unilateral occlusion of the common carotid artery, was accompanied by injury to the neurons of the hippocampi of both hemispheres, which was more pronounced on the side of the occlusion. This damage, as well as the mechanisms of neuroprotection induced by hypoxic preconditioning, were maintained for at least 8 weeks by mechanisms mediated through a7nAChRs. Deficite of a7nAChRs was accompanied with reduction of neuronal damage caused CCH in 8 weeks, as well as preconditioning effects, and lead to compensatory activation of regulatory and protective mechanisms mediated by SIRT1, in normal conditions and in CCH. In wild-type (C57) mice, protective mechanisms in CCH were realized to a greater extent by increased expression of SIRT3 in both hemispheres of the brain.

Se sabe que el precondicionamiento hipóxico induce neuroprotección, pero aún se desconocen sus efectos y vías en la patología cerebral crónica. El objetivo fue establecer la participación de la subunidad a7 de los receptores nicotínicos de acetilcolina (a7nAchR) y las sirtuinas de tipo 1 (SIRT1) y 3 (SIRT3) en los efectos del precondicionamiento hipóxico hipobárico sobre el daño cerebral en ratones con hipoperfusión cerebral crónica causada por la oclusión de la arteria carótida común izquierda. Los ratones macho C57/6j (C57, tipo salvaje) y a7nAchRs(-/-) se dividieron en seis grupos experimentales (10 ratones por grupo): C57 con operación simulada, C57 con hipoperfusión cerebral crónica, C57 con precondicionamiento hipobárico hipóxico y crónica. hipoperfusión cerebral, ratones a7nAchRs(-/-) operados de forma simulada, a7nAchRs(-/-) con hipoperfusión cerebral crónica, a7nAchRs(-/-) con precondicionamiento hipobárico hipóxico e hipoperfusión cerebral crónica. Para el preacondicionamiento, los ratones fueron expuestos a hipoxia "levantándolos" en una cámara de barro a una altitud simulada de 5600 m s.n.m. durante 1 h/día durante 3 días consecutivos antes de la manipulación quirúrgica. Se examinaron las expresiones de SIRT1, SIRT3 en tejido cerebral y los cambios histopatológicos de los hipocampos. Se demostró que la hipoperfusión cerebral crónica de 8 semanas, causada por la oclusión unilateral de la arteria carótida común, se acompañaba de lesión de las neuronas del hipocampo de ambos hemisferios y que era más pronunciada en el lado de la oclusión. Este daño, así como los mecanismos de neuroprotección inducidos por el precondicionamiento hipóxico, se mantuvieron durante al menos 8 semanas mediante mecanismos mediados por a7nAChR. El déficit de a7nAChR se acompañó de una reducción del daño neuronal causado por CCH en 8 semanas, así como de efectos de precondicionamiento, y condujo a una activación compensatoria de mecanismos reguladores y protectores mediados por SIRT1, en condiciones normales y en CCH. En ratones de tipo salvaje (C57), los mecanismos de protección en CCH se realizaron en mayor medida mediante una mayor expresión de SIRT3 en ambos hemisfe- rios del cerebro.

Endovascular Reperfusion for Acute Isolated Cervical Carotid Occlusions: The Concept of "Hemodynamic Thrombectomy".

BACKGROUND/AIMS: Endovascular treatment improves the outcomes of patients presenting with acute large vessel occlusions. Isolated proximal carotid occlusions presenting with hemodynamic ischemic stroke may probably also benefit from endovascular treatment. We aimed to assess the clinical and radiological data findings on patients who underwent endovascular treatment for acute ischemic stroke related to an isolated cervical carotid artery occlusion. METHODS: Of a consecutive series of 223 patients who were admitted with acute ische-mic stroke and were treated by thrombectomy, we included 9 patients with isolated cervical internal carotid occlusions. RESULTS: The mean baseline National Institutes of Health Stroke Scale (NIHSS) score was 11.8. Complete carotid recanalization was achieved in 5 of the 9 patients (55.5%). In 2 patients, vertebral angioplasty was performed to improve the collateral flow. All patients had a modified Thrombolysis in Cerebral Infarction (mTICI) score of 3 at the end of the procedures. A good neurological outcome, defined as a modified Rankin Scale score ≤2 at the 3-month follow-up, was observed in 6 patients (66.7%). No symptomatic intracranial hemorrhages or deaths occurred during the 3 months of follow-up. CONCLUSIONS: The endovascular recanalization of isolated cervical carotid occlusions presenting with acute ischemic stroke symptoms is feasible. Because isolated cervical carotid occlusions are associated with hemodynamic ischemic symptoms, if carotid recanalization cannot be achieved, stenting other cervical arteries' stenoses, with a focus on intracranial flow improvement, appears to be a reasonable strategy. Large controlled studies are necessary to assess the safety and efficacy of recanalization of acute isolated cervical carotid occlusions.

Long-Term Effects of Hypoxia-Reoxygenation on Thioredoxins in Rat Central Nervous System.

BACKGROUND: Oxidative stress induced by the oxidative pathway dysregulation following ischemia/ reperfusion has been proposed as an important cause of neuronal death and brain damage. The proteins of the thioredoxin (Trx) family are crucial mediators of protein function regulating the intracellular hydrogen peroxide levels and redox-sensitive post-translational protein changes. AIM: To analyze the expression and distribution of fourteen members of the Trx family, potentially essential for the regeneration upon long-term brain damage, in a perinatal hypoxia-ischemia rat model induced by common carotid artery ligation. METHODS: The right common carotid artery (CCA) was exposed by an incision on the right side of the neck, isolated from nerve and vein, and permanently ligated. Sham-surgery rats underwent right CCA surgical exposure but no ligation. Euthanasia was administered to all rats at 30, 60, and 90 days of age. Protein expression and distribution of fourteen members of the Trx family and related proteins (Grx1, Grx2, Grx3, Grx5, Prx1, Prx2, Prx3, Prx4, Prx5, Prx6, Trx1, Trx2, TrxR1, TrxR2) was examined in the most hypoxia susceptible rat brain areas, namely, cerebellum, corpus striatum, and the hippocampus. RESULTS: The thioredoxin proteins displayed a complex, cell-type, and tissue-specific expression pattern following ischemia/reperfusion. Even 60 days after ischemia/reperfusion, Western blot analysis showed a persistent expression of Trx1 and Grx2 in several brain areas. CONCLUSION: The Trx family of proteins might contribute to long-term survival and recovery supporting their therapeutic use to curtail ischemic brain oxidative damage following an ischemia/reperfusion insult. Characterization of ischemia/reperfusion oxidative brain damage and analysis of the involved mechanisms are required to understand the underneath processes triggered by ischemia/reperfusion and to what extent and in what way thioredoxins contribute to recovery from brain hypoxic stress.

Oxiracetam ameliorates cognitive deficits in vascular dementia rats by regulating the expression of neuronal apoptosis/autophagy-related genes associated with the activation of the Akt/mTOR signaling pathway

Oxiracetam (ORC) is a commonly used nootropic drug for improving cognition and memory impairments. The therapeutic effect and underlying mechanism of ORC in vascular dementia (VaD) treatment remain unknown. In this study, 3-month-old male Sprague-Dawley rats with permanent bilateral common carotid artery occlusion-induced VaD were treated orally with low (100 mg/kg) or high (200 mg/kg) dose ORC once a day for 4 weeks. The results of the Morris water maze test and Nissl staining showed that ORC treatment significantly alleviated learning and memory deficits and neuronal damage in rats with VaD. Mechanistically, the protein levels of a panel of genes associated with neuronal apoptosis (Bcl-2, Bax) and autophagy (microtubule-associated protein 1 chain 3, Beclin1, p62) were significantly altered by ORC treatment compared with VaD, suggesting a protective role of ORC against VaD-induced neuronal apoptosis and autophagy. Moreover, the Akt/mTOR pathway, which is known to be the upstream signaling governing apoptosis and autophagy, was found to be activated in ORC-treated rats, suggesting an involvement of Akt/mTOR activation in ORC-rendered protection in VaD rats. Taken together, this study demonstrated that ORC may alleviate learning and memory impairments and neuronal damage in VaD rats by altering the expression of apoptosis/autophagy-related genes and activation of the Akt/mTOR signaling pathway in neurons.

Neuroprotective effects of erythropoietin on rat retinas subjected to oligemia

OBJECTIVES: Erythropoietin may have neuroprotective potential after ischemia of the central nervous system. Here, we conducted a study to characterize the protective effects of erythropoietin on retinal ganglion cells and gliotic reactions in an experimentally induced oligemia model. METHODS: Rats were subjected to global oligemia by bilateral common carotid artery occlusion and then received either vehicle or erythropoietin via intravitreal injection after 48 h; they were euthanized one week after the injection. The densities of retinal ganglion cells and contents of glial fibrillary acidic protein (astrocytes/Müller cells) and cluster of differentiation 68 clone ED1 (microglia/macrophages), assessed by fluorescence intensity, were evaluated in frozen retinal sections by immunofluorescence and epifluorescence microscopy. RESULTS: Retinal ganglion cells were nearly undetectable one week after oligemia compared with the sham controls; however, these cells were partially preserved in erythropoietin-treated retinas. The contents of glial fibrillary acidic protein and cluster of differentiation 68 clone ED1, markers for reactive gliosis, were significantly higher in retinas after bilateral common carotid artery occlusion than those in both sham and erythropoietin-treated retinas. CONCLUSIONS: The number of partially preserved retinal ganglion cells in the erythropoietin-treated group suggests that erythropoietin exerts a neuroprotective effect on oligemic/ischemic retinas. This effect could be related to the down-modulation of glial reactivity, usually observed in hypoxic conditions, clinically observed during glaucoma or retinal artery occlusion conditions. Therefore, glial reactivity may enhance neurodegeneration in hypoxic conditions, like normal-tension glaucoma and retinal ischemia, and erythropoietin is thus a candidate to be clinically applied after the detection of decreased retinal blood flow.

The importance of internal carotid artery occlusion tolerance test in carotid endarterectomy under locoregional anesthesia.

BACKGROUNDS: Carotid endarterectomy is considered a safe and effective method for preventing stroke in the short and long term in patients with severe carotid stenosis. The internal carotid artery (ICA) occlusion tolerance test was performed to evaluate cerebral tolerance during temporary carotid occlusion, defined as the capacity of the cerebral hemisphere to maintain adequate cerebral blood flow during occlusion of the ICA. Thus, the aim of the present study is to determine the importance of this test in patients undergoing carotid endarterectomy. METHODS: From August 2008 to May 2015, 115 consecutive patients (39 female, 77 male) were referred for carotid endarterectomy at the Santa Casa de Belo Horizonte by the main author. RESULTS: Of the 115 patients who participated in the study, 107 were submitted to carotid endarterectomy. Morbi-mortality was 2.7 %. The presence of deficits during the ICA occlusion tolerance test in less than 30 s was associated with the presence of complications. Among the 104 patients who showed no deficits during the test, only one case (0.9 %) presented complications, while among the three cases that showed deficits during the test and who were submitted to carotid endarterectomy, two cases presented complications (p < 0.0001). CONCLUSIONS: The carotid endarterectomy under locoregional anesthesia is a safe surgical procedure. The internal carotid artery occlusion tolerance test can help identify high-risk patients who have been assigned this treatment.

Rolipram improves cognition, reduces anxiety- and despair-like behaviors and impacts hippocampal neuroplasticity after transient global cerebral ischemia.

Cognitive impairment, anxiety- and depressive-like symptoms are well recognized outcome of cerebral ischemia in clinical and preclinical settings. Rolipram, a phosphodiesterase-4 (PDE-4) inhibitor, improves cognition and produces anxiolytic- and antidepressant-like effects in rodents. Rolipram also exerts anti-inflammatory effects and enhances survival of newborn hippocampal neurons in mice subjected to transient global cerebral ischemia. Here, we evaluated the effects of chronic rolipram treatment in mice subjected to transient global brain ischemia. C56B6/7 mice were subjected to bilateral common carotid artery occlusion (BCCAO) and were then tested in a multi-tiered behavioral battery including the elevated zero maze (EZM), open field (OF), object location test (OLT), and forced swim test (FST). We also investigated the effects of rolipram on hippocampal neurodegeneration and the expression of the neuronal plasticity markers doublecortin (DCX) and microtubule-associated protein (MAP-2). Ischemic mice exhibited memory deficits OLT, higher levels of anxiety EZM and behavioral despair FST. BCCAO caused neuronal loss in the CA3 hippocampal subfield and basolateral amygdala (BLA). In the hippocampus of BCCAO mice, a disrupted neuronal plasticity was evidenced by decreased DCX expression. Chronic treatment with rolipram attenuated the behavioral effects of BCCAO. Rolipram also decreased neurodegeneration in the CA3 while it increased dendritic arborization of DCX-immunoreactive (DCX-IR) neurons and microtubule associate MAP-2 expression in the hippocampus of BCCAO mice. These data suggest that chronic inhibition of PDE-4 can be a useful therapeutic strategy to improve the emotional and cognitive outcomes of transient global cerebral ischemia.

Common Carotid Artery Occlusion: A Single-Center Experience in 40 Cases.

The incidence of common carotid artery occlusion (CCAO) is approximately 3% in patients who undergo angiography for symptomatic cerebrovascular disease; however, few studies have reported on management of this condition. The objective of this article was to analyze risk factors, therapeutic options, and clinical benefits of surgical treatment at a hospital in the city of São Paulo, Brazil. Data were collected from medical records of 40 patients with CCAO who were treated from June 2002 to October 2013. Results were analyzed retrospectively. Most of the patients were men (63.0%), who were significantly younger than women. Most of the participants had hypertension (90.0%), and more than half had a history of smoking (52.5%). The mean number of coexisting comorbidities/risk factors was 2.9 ± 1.0. Half of our sample had ipsilateral patent internal and external carotid artery, and 32.5% presented with an occluded internal carotid artery and a patent external artery. Patients with both an internal and an external occluded carotid artery (12.5%) were significantly older. Contralateral arteriosclerosis was observed in 65% of the patients, mainly represented by 50 to 90% stenosis. Most patients were symptomatic (67.5%), and hemiparesis was the most common symptom (55.0%) found. Most (77.5%) of the patients underwent the medical treatment; one out of three endovascular approaches failed. During the mean follow-up of 55 ± 43 months (range, 2-136 months), 17.5% of the patients died within 4 days after surgical repair and after along 123 months of clinical follow-up. Coexisting comorbidities/risk factors were significantly associated with fatal outcomes, such as acute myocardial infarction. This study provides scientific evidences on treatment and outcomes of CCAO.

Thioredoxin 1 and glutaredoxin 2 contribute to maintain the phenotype and integrity of neurons following perinatal asphyxia.

BACKGROUND: Thioredoxin (Trx) family proteins are crucial mediators of cell functions via regulation of the thiol redox state of various key proteins and the levels of the intracellular second messenger hydrogen peroxide. Their expression, localization and functions are altered in various pathologies. Here, we have analyzed the impact of Trx family proteins in neuronal development and recovery, following hypoxia/ischemia and reperfusion. METHODS: We have analyzed the regulation and potential functions of Trx family proteins during hypoxia/ischemia and reoxygenation of the developing brain in both an animal and a cellular model of perinatal asphyxia. We have analyzed the distribution of 14 Trx family and related proteins in the cerebellum, striatum, and hippocampus, three areas of the rat brain that are especially susceptible to hypoxia. Using SH-SY5Y cells subjected to hypoxia and reoxygenation, we have analyzed the functions of some redoxins suggested by the animal experiment. RESULTS AND CONCLUSIONS: We have described/discovered a complex, cell-type and tissue-specific expression pattern following the hypoxia/ischemia and reoxygenation. Particularly, Grx2 and Trx1 showed distinct changes during tissue recovery following hypoxia/ischemia and reoxygenation. Silencing of these proteins in SH-SY5Y cells subjected to hypoxia-reoxygenation confirmed that these proteins are required to maintain the normal neuronal phenotype. GENERAL SIGNIFICANCE: These findings demonstrate the significance of redox signaling in cellular pathways. Grx2 and Trx1 contribute significantly to neuronal integrity and could be clinically relevant in neuronal damage following perinatal asphyxia and other neuronal disorders.

Enxerto subclávio-carotídeo como método de tratamento na obstrução da artéria carótida comum / Subclavian-carotid bypass graft for the occlusion of the common carotid artery

A oclusão isolada da artéria carótida comum (ACC) é uma lesão relativamente incomum (0,5 a 5 por cento). A maioria dos pacientes com obstrução da ACC tem lesão concomitante na artéria carótida interna (ACI) e na artéria carótida externa (ACE) ipsilaterais, sendo que, ocasionalmente, a circulação colateral da ACE pode preservar a perviedade da ACI via fluxo retrógrado. Relatamos o caso de um paciente sintomático com oclusão da ACC e perviedade das ACI e ACE tratado cirurgicamente com enxerto subclávio-carotídeo.

Isolated occlusion of the common carotid artery (CCA) is a relatively uncommon lesion (0.5 to 5 percent). Most patients with occlusion of the CCA have concomitant lesions of the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA), and ECA may occasionally preserve ICA patency by means of retrograde flow. We report the case of a symptomatic patient with occlusion of the CCA and patency of the ICA and ECA treated with subclavian-carotid bypass graft.

Spontaneous recanalization after complete occlusion of the common carotid artery with subsequent embolic ischemic stroke.

INTRODUCTION: Acute carotid artery occlusion carries a high morbidity and mortality. Acute angioplasty and stenting is a feasible option with little known about the long term outcome. Limiting factor for this approach is hyperperfusion syndrome or hemorrhagic infarction. Spontaneous early or late recanalization for extracranial vessel is in the range of 5% -30%, with no well defined clinical outcome data. We describe a case of spontaneous common carotid recanalization. CASE REPORT: An 88 year old man presented with right sided weakness, global aphasia and visual field loss and was discovered to have common carotid occlusion at its origin. Within 12 hours of symptom onset patient improved neurologically to his baseline exam and repeat imaging demonstrated spontaneous recanalization. This was followed symptomatic occlusion of left middle cerebral artery The patient was treated with multimodality approach resulting in complete revascularization of the middle cerebral artery and angioplasty and stent placement of the internal carotid artery. Patient had a good neurological outcome at 3 months followup. CONCLUSION: The present case report demonstrates the risk of spontaneous recanalization acutely in patients presenting with common carotid artery occlusion and associated risk of embolic strokes. In such a patient, concomitant treatment for intracranial occlusion and extracranial high grade stenosis may be performed safely after 30 hours from the initial symptom onset.