Unilateral Common Carotid Artery Research Articles

Abstract TMP96: Neuroinflammatory Mechanism of Vascular Cognitive Impairment

Introduction: The mechanisms of vascular cognitive impairment (VCI) are poorly understood. We previously demonstrated increased expression and activity of soluble epoxide hydrolase (sEH) in microvascular endothelium of human brain tissue from deceased patients with pre-mortem VCI. sEH is a key enzyme in the inactivation of endogenous lipid signaling mediators, epoxyeicosatrienoic acids (EETs), known to have vasodilator and anti-inflammatory properties. Hypothesis: Upregulation of endothelial sEH impairs cognition, by mechanisms involving reduced cerebral blood flow (CBF) and enhanced inflammation. Methods: Mice constitutively expressing human sEH in endothelium (Tie2-hsEH) and wild-type (WT) underwent unilateral common carotid artery occlusion (UCCAO) or sham surgery, then analyzed 4 months later for cognitive performance using the Morris water maze (MWM), CBF by perfusion MRI, immune cell profiling in brain, blood and spleen using fluorescence-activated cell sorting (FACS) and immunohistochemistry (IHC). Additionally, immune profiling was performed on WT mice 28 days following surgery, with and without pretreatment with immune modulator DRa1-hMOG-35-55 (HLA-DR a1 moiety linked to human MOG-35-55 peptide). Results: Tie2-hsEH mice showed impaired spatial memory retention in the MWM. No differences were observed in CBF between genotypes. IHC demonstrated a higher density of CD45-positive cells in Tie2-hsEH brain compared to WT. FACS analysis revealed a higher frequency of CD11b + CD45 hi cells in Tie2-hsEH vs. WT mice. Furthermore, these cells express higher levels of CD74, the receptor for macrophage migration inhibitory factor (MIF). Similarly, following UCCAO, the frequency of antigen-presenting dendritic cells and CD74 expression on CD11b + CD45 hi cells were increased in brain, but reduced in spleen and blood compared to naïve mice; both changes were reversed by treatment with DRa1-MOG-35-55, resulting in a decreased frequency and activation state of these cells. Conclusions: Our data suggest that infiltration of monocyte-derived macrophages may contribute to cognitive impairment in VCI. Our findings suggest that CD74 expression could serve as a biomarker for VCI, and that DRa1-MOG-35-55 may be effective in treating VCI.

Abstract WMP36: Inhibition of the Endothelial Shear Stress Sensor, P2x4 Purinoceptor Drastically Reduces Cerebral Aneurysm Formation

Background and purpose: Although the assumption that wall shear stress-related hemodynamics is closely involved in cerebral aneurysm formation is now widely accepted, direct evidence still remains to be presented. Here, we examine a role of shear stress in cerebral aneurysm development, focused on a vascular endothelial shear sensor, P2X4 purinoceptor. Methods: P2X4 knockout mice and wild type mice were subjected to cerebral aneurysm-generating surgery with ligation of unilateral common carotid artery and renal hypertension. Damage to the internal elastic lamina, early phase aneurysm development, and the incidence of aneurysm induction were examined by light microscope. The expression of biochemical contributors to aneurysm formation was immunohistochemically examined. Additionally, the P2X4 purinoceptor inhibitor, paroxetine (10mg/kg/day) was administered to Sprague-Dawley rats after aneurysm-inducing surgery, and the incidence of aneurysm formation was examined. Results: Damage to the internal elastic lamina and the frequency of CA induction were significantly diminished in P2X4 knockout mice compared to control wild-type mice after CA-inducing surgery ( p =0.027 and 0.018, respectively). Expression levels of known contributors to aneurysm formation, iNOS, MCP-1, cathepsin L, and COX-2, were immunohistochemically weakened in P2X4 KO mice compared to wild-type mice. Moreover, paroxetine significantly attenuated the incidence of induced aneurysms in rats ( p =0.031). Conclusions: Disruption of the endothelial shear stress sensor, P2X4 purinoceptor drastically reduces cerebral aneurysm formation, suggesting that shear stress-related hemodynamics initiates cerebral aneurysm formation. The P2X4 purinoceptor inhibitor paroxetine, which is also prescribed to human as an antidepressant, may be a potential clinical prophylactic agent against cerebral aneurysm formation.

A Mouse Model for Chronic Cerebral Hypoperfusion-induced Cognitive Dysfunction

Background: Chronic cerebral hypoperfusion potentially contributes to the initiation and progression of vascular dementia (VD). Bilateral common carotid artery occlusion (two-vessel occlusion) is the most commonly used animal model to replicate this pathological condition but with high mortality and severe histological cerebral damage. Unilateral common carotid artery occlusion (one-vessel occlusion) was introduced to simulate clinical conditions. Our study was designed to further characterize this model.Methods: In this study, eight-week old CD-1 mice were subjected to left common carotid artery occlusion (LCCAO). Two weeks after the occlusion, their learning and memory were assessed by Barnes maze and fear conditioning. Histo-morphological changes were evaluated by Hematoxylin-Eosin staining. Neuronal and axonal degenerative changes were examined by amino-cupric sliver staining.Results: LCCAO increased the time to find the target box in the Barnes maze test during the 4-day training sessions and one day after the training sessions compared with sham group mice. There was no difference in context-related or tone-related freezing behavior between these two groups. No significant histological neuronal cell damage or degeneration was observed in brain sections of hippocampus and corpus callosum in these two groups.Conclusions: Our results suggest that LCCAO can be used to mimic the vascular dementia. Citation: Jun Li, Zhi-Yi Zuo. A mouse model for chronic cerebral hypoperfusion-induced cognitive dysfunction. J Anesth Perioper Med 2017; 4: 60-66. doi:10.24015/JAPM.2017.0015This is an open-access article, published by Evidence Based Communications (EBC). This work is licensed under the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium or format for any lawful purpose. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Combined Hemorrhagic Shock and Unilateral Common Carotid Occlusion Induces Neurological Injury in Adult Male Rats.

Background: Clinical assessment reveals that patients after surgery of cardiopulmonary bypass or coronary bypass experience postoperative cognitive dysfunction. This study aimed to investigate whether resuscitation after a hemorrhagic shock (HS) and/or mild cerebral ischemia caused by a unilateral common carotid artery occlusion (UCCAO) can cause brain injury and concomitant neurological dysfunction, and explore the potential mechanisms.Methods: Blood withdrawal (6 mL/100 g body weight) for 60 min through the right jugular vein catheter-induced an HS. Immediately after the termination of HS, we reinfused the initially shed blood volumes to restore and maintain the mean arterial blood pressure (MABP) to the original value during the 30-min resuscitation. A cooling water blanket used to induce whole body cooling for 30 min after the end of resuscitation.Results: An UCCAO caused a slight cerebral ischemia (cerebral blood flow [CBF] 70%) without hypotension (MABP 85 mmHg), systemic inflammation, multiple organs injuries, or neurological injury. An HS caused a moderate cerebral ischemia (52% of the original CBF levels), a moderate hypotension (MABP downed to 22 mmHg), systemic inflammation, and peripheral organs injuries. However, combined an UCCAO and an HS caused a severe cerebral ischemia (18% of the original CBF levels), a moderate hypotension (MABP downed to 17 mmHg), systemic inflammation, peripheral organs damage, and neurological injury, which can be attenuated by whole body cooling.Conclusions: When combined with an HS, an UCCAO is associated with ischemic neuronal injury in the ipsilateral hemisphere of adult rat brain, which can be attenuated by therapeutic hypothermia. A resuscitation from an HS regards as a reperfusion insult which may induce neurological injury in patients with an UCCAO disease.

Effects of Acute Systemic Hypoxia and Hypercapnia on Brain Damage in a Rat Model of Hypoxia-Ischemia.

Therapeutic hypercapnia has the potential for neuroprotection after global cerebral ischemia. Here we further investigated the effects of different degrees of acute systemic hypoxia in combination with hypercapnia on brain damage in a rat model of hypoxia and ischemia. Adult wistar rats underwent unilateral common carotid artery (CCA) ligation for 60 min followed by ventilation with normoxic or systemic hypoxic gas containing 11%O2,13%O2,15%O2 and 18%O2 (targeted to PaO2 30–39 mmHg, 40–49 mmHg, 50–59 mmHg, and 60–69 mmHg, respectively) or systemic hypoxic gas containing 8% carbon dioxide (targeted to PaCO2 60–80 mmHg) for 180 min. The mean artery pressure (MAP), blood gas, and cerebral blood flow (CBF) were evaluated. The cortical vascular permeability and brain edema were examined. The ipsilateral cortex damage and the percentage of hippocampal apoptotic neurons were evaluated by Nissl staining and terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-biotin nick end labeling (TUNEL) assay as well as flow cytometry, respectively. Immunofluorescence and western blotting were performed to determine aquaporin-4 (AQP4) expression. In rats treated with severe hypoxia (PaO2 < 50 mmHg), hypercapnia augmented the decline of MAP with cortical CBF and damaged blood–brain barrier permeability (p < 0.05). In contrast, in rats treated with mild to moderate hypoxia (PaO2 > 50 mmHg), hypercapnia protected against these pathophysiological changes. Moreover, hypercapnia treatment significantly reduced brain damage in the ischemic ipsilateral cortex and decreased the percentage of apoptotic neurons in the hippocampus after the CCA ligated rats were exposed to mild or moderate hypoxemia (PaO2 > 50 mmHg); especially under mild hypoxemia (PaO2 > 60 mmHg), hypercapnia significantly attenuated the expression of AQP4 protein with brain edema (p < 0.05). Hypercapnia exerts beneficial effects under mild to moderate hypoxemia and augments detrimental effects under severe hypoxemia on brain damage in a rat model of hypoxia-ischemia.

Impaired Collateral Flow Compensation During Chronic Cerebral Hypoperfusion in the Type 2 Diabetic Mice.

The presence of collaterals is associated with a reduced risk of stroke and transient ischemic attack in patients with steno-occlusive carotid artery disease. Although metabolic syndrome negatively impacts collateral status, it is unclear whether and to what extent type 2 diabetes mellitus affects cerebral collateral flow regulation during hypoperfusion. We examined the spatial and temporal changes of the leptomeningeal collateral flow and the flow dynamics of the penetrating arterioles in the distal middle cerebral artery and anterior cerebral artery branches over 2 weeks after unilateral common carotid artery occlusion (CCAO) using optical coherent tomography in db/+ and db/db mice. We also assessed the temporal adaptation of the circle of Willis after CCAO by measuring circle of Willis vessel diameters. After unilateral CCAO, db/db mice exhibited diminished leptomeningeal collateral flow compensation compared with db/+ mice, which coincided with a reduced dilation of distal anterior cerebral artery branches, leading to reduced flow not only in pial vessels but also in penetrating arterioles bordering the distal middle cerebral artery and anterior cerebral artery. However, no apparent cell death was detected in either strain of mice during the first week after CCAO. db/db mice also experienced a more severe early reduction in the vessel diameters of several ipsilateral main feeding arteries in the circle of Willis, in addition to a delayed post-CCAO adaptive response by 1 to 2 weeks, compared with db/+ mice. Type 2 diabetes mellitus is an additional risk factor for hemodynamic compromise during cerebral hypoperfusion, which may increase the severity and the risk of stroke or transient ischemic attack.

Endogenous Polysialic Acid Based Micelles for Calmodulin Antagonist Delivery against Vascular Dementia.

Clinical treatment for vascular dementia still remains a challenge mainly due to the blood-brain barrier (BBB). Here, a micelle based on polysialic acid (PSA), which is a hydrophilic and endogenous carbohydrate polymer, was designed to deliver calmodulin antagonist for therapy of vascular dementia. PSA was first chemically conjugated with octadecylamine (ODA), and the obtained PSA-ODA copolymer could self-assemble into micelle in aqueous solution with a 120.0 μg/mL critical micelle concentration. The calmodulin antagonist loaded PSA-ODA micelle, featuring sustained drug release behavior over a period of 72 h with a 3.6% (w/w) drug content and a 107.0 ± 4.0 nm size was then fabricated. The PSA-ODA micelle could cross the BBB mainly via active endocytosis by brain endothelial cells followed by transcytosis. In a water maze test for spatial learning, calmodulin antagonist loaded PSA-ODA micelle significantly reduced the escape latencies of right unilateral common carotid arteries occlusion (rUCCAO) mice with dosage significantly reduced versus free drug. The decrease of hippocampal phospho-CaMKII (Thr286/287) and phospho-synapsin I (Ser603) was partially restored in rUCCAO mice following calmodulin antagonist loaded PSA-ODA micelle treatment. Consistent with the restored CaMKII phosphorylation, the elevation of BrdU/NeuN double-positive cells in the same context was also observed. Overall, the PSA-ODA micelle developed from the endogenous material might promote the development of therapeutic approaches for improving the efficacy of brain-targeted drug delivery and have great potential for vascular dementia treatment.

Adenosine A1-Receptors Modulate mTOR Signaling to Regulate White Matter Inflammatory Lesions Induced by Chronic Cerebral Hypoperfusion.

We sought to investigate the role of the adenosine A1 receptors (A1ARs) in white matter lesions under chronic cerebral hypoperfusion (CCH) and explore the potential repair mechanisms by activation of the receptors. A right unilateral common carotid artery occlusion (rUCCAO) method was used to construct a CCH model. 2-chloro-N6-cyclopentyladenosine (CCPA), a specific agonist of A1ARs, was used to explore the biological mechanisms of repair in white matter lesions under CCH. The expression of mammalian target of rapamycin (mTOR), phosphorylation of mTOR (P-mTOR), myelin basic protein (MBP, a marker of white matter myelination) were detected by Western-blot. Pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) and anti-inflammatory cytokine interleukin-10 (IL-10) levels were determined by ELISA. Compared with the control groups on week 2, 4 and 6, in CCPA-treated groups, the ratio of P-mTOR/mTOR, expression of MBP and IL-10 increased markedly, while the expression of TNF-α reduced at week 6. In conclusion, A1ARs appears to reduce inflammation in white matter via the mTOR signaling pathway in the rUCCAO mice. Therefore, A1ARs may serve as a therapeutic target during the repair of white matter lesions under CCH.

Interleukin-1β impedes oligodendrocyte progenitor cell recruitment and white matter repair following chronic cerebral hypoperfusion

Subcortical ischemic vascular dementia (SIVD) caused by chronic cerebral hypoperfusion exhibits progressive white matter and cognitive impairments. However, its pathogenetic mechanisms are poorly understood. We investigated the role of interleukin-1β (IL-1β) and its receptor IL-1 receptor type 1 (IL-1R1) in an experimental SIVD model generated via right unilateral common carotid arteries occlusion (rUCCAO) in mice. We found that IL-1β expression was elevated in the corpus callosum at the early stages after rUCCAO. IL-1 receptor antagonist (IL-1Ra), when delivered at an early stage, as well as IL-1R1 knockout, rescued the downregulation of myelin basic protein (MBP) and improved remyelination at the later stage after rUCCAO. Our data suggest that the recruitment of OPCs, but not the proliferation or differentiation of OPCs, is the only compromised step of remyelination following chronic cerebral ischemia. IL-1Ra treatment and IL-1R1 knockout had no effect on the oligodendrocyte progenitor cell (OPC) proliferation, but did promote the recruitment of newly generated OPCs to the corpus callosum, which can be reversed by compensatory expression of IL-1R1 in the SVZ of IL-1R1 knockout mice. Further, we found that recruited OPCs contribute to oligodendrocyte regeneration and functional recovery. In transwell assays, IL-1β inhibited OPC migration through IL-1R1. Moreover, KdPT which can enter the brain to block IL-1R1 also showed comparable protection when intraperitoneally delivered. Our results suggest that IL-1β during the early stages following chronic cerebral hypoperfusion impedes OPC recruitment via IL-1R1, which inhibits white matter repair and functional recovery. IL-1R1 inhibitors may have potential uses in the treatment of SIVD.

Influence of rat adipose tissue-derived mesenchymal stem cells on brain tissues following permanent unilateral common carotid artery occlusion in adult male albino rat

Log in or Register Subscribe to journalSubscribe Get new issue alertsGet alerts Enter your Email address: Wolters Kluwer Health may email you for journal alerts and information, but is committed to maintaining your privacy and will not share your personal information without your express consent. For more information, please refer to our Privacy Policy. Subscribe to eTOC Secondary Logo Journal Logo All Articles Images Videos Podcasts Blogs Advanced Search Toggle navigation Subscribe Register Login Articles & Issues Current IssuePrevious Issues - 2011 Onwards For Authors Information for AuthorsEditing Services Journal Info About the JournalEditorial BoardAdvertisingOpen AccessSubscription ServicesReprintsJob OpportunitiesRights and Permissions All Articles Images Videos Podcasts Blogs Advanced Search

In vivo evidence for long-term vascular remodeling resulting from chronic cerebral hypoperfusion in mice

We have characterized both acute and long-term vascular and metabolic effects of unilateral common carotid artery occlusion in mice by in vivo magnetic resonance imaging and positron emission tomography. This common carotid artery occlusion model induces chronic cerebral hypoperfusion and is therefore relevant to both preclinical stroke studies, where it serves as a control condition for a commonly used mouse model of ischemic stroke, and neurodegeneration, as chronic hypoperfusion is causative to cognitive decline. By using perfusion magnetic resonance imaging, we demonstrate that under isoflurane anesthesia, cerebral perfusion levels recover gradually over one month. This recovery is paralleled by an increase in lumen diameter and altered tortuosity of the contralateral internal carotid artery at one year post-ligation as derived from magnetic resonance angiography data. Under urethane/α-chloralose anesthesia, no acute perfusion differences are observed, but the vascular response capacity to hypercapnia is found to be compromised. These hemispheric perfusion alterations are confirmed by water [15O]-H2O positron emission tomography. Glucose metabolism ([18F]-FDG positron emission tomography) or white matter organization (diffusion-weighted magnetic resonance imaging) did not show any significant alterations. In conclusion, permanent unilateral common carotid artery occlusion results in acute and long-term vascular remodeling, which may have immediate consequences for animal models of stroke but also vascular dementia.

Heme Oxygenase-1 Mediates Neuroprotection Conferred by Argon in Combination with Hypothermia in Neonatal Hypoxia-Ischemia Brain Injury.

Hypoxic-ischemic encephalopathy is a major cause of mortality and disability in the newborn. The authors investigated the protective effects of argon combined with hypothermia on neonatal rat hypoxic-ischemic brain injury. In in vitro studies, rat cortical neuronal cell cultures were challenged by oxygen and glucose deprivation for 90 min and exposed to 70% Ar or N2 with 5% CO2 balanced with O2, at 33°C for 2 h. Neuronal phospho-Akt, heme oxygenase-1 and phospho-glycogen synthase kinase-3β expression, and cell death were assessed. In in vivo studies, neonatal rats were subjected to unilateral common carotid artery ligation followed by hypoxia (8% O2 balanced with N2 and CO2) for 90 min. They were exposed to 70% Ar or N2 balanced with oxygen at 33°, 35°, and 37°C for 2 h. Brain injury was assessed at 24 h or 4 weeks after treatment. In in vitro studies, argon-hypothermia treatment increased phospho-Akt and heme oxygenase-1 expression and significantly reduced the phospho-glycogen synthase kinase-3β Tyr-216 expression, cytochrome C release, and cell death in oxygen-glucose deprivation-exposed cortical neurons. In in vivo studies, argon-hypothermia treatment decreased hypoxia/ischemia-induced brain infarct size (n = 10) and both caspase-3 and nuclear factor-κB activation in the cortex and hippocampus. It also reduced hippocampal astrocyte activation and proliferation. Inhibition of phosphoinositide-3-kinase (PI3K)/Akt pathway through LY294002 attenuated cerebral protection conferred by argon-hypothermia treatment (n = 8). Argon combined with hypothermia provides neuroprotection against cerebral hypoxia-ischemia damage in neonatal rats, which could serve as a new therapeutic strategy against hypoxic-ischemic encephalopathy.

Tideglusib, a chemical inhibitor of GSK3β, attenuates hypoxic-ischemic brain injury in neonatal mice

BackgroundHypoxia-ischemia is an important cause of brain injury and neurological morbidity in the newborn infants. The activity of glycogen synthase kinase-3β (GSK-3β) is up-regulated following neonatal stroke. Tideglusib is a GSK-3β inhibitor which has neuroprotective effects against neurodegenerative diseases in clinical trials. However, the effect of tideglusib on hypoxic-ischemic (HI) brain injury in neonates is still unknown. MethodsPostnatal day 7 (P7) mouse pups subjected to unilateral common carotid artery ligation followed by 1h of hypoxia or sham surgery was performed. HI animals were administered tideglusib (5mg/kg) or vehicle intraperitoneally 20min prior to the onset of ischemia. The brain infarct volume and whole brain images, were used in conjunction with Nissl staining to evaluate the protective effects of tideglusib. Protein levels of glial fibrillary acidic protein (GFAP), Notch1, cleaved caspase-3/9, phosphorylated signal transducer and activator of transcription 3 (STAT3), GSK-3β and protein kinase B (Akt) were detected to identify potentially involved molecules. ResultsTideglusib significantly reduced cerebral infarct volume at both 24h and 7days after HI injury. Tideglusib also increased phosphorylated GSK-3β(Ser9) and Akt(Ser473), and reduced the expression of GFAP and p-STAT3(Tyr705). In addition, pretreatment with tideglusib also enhanced the protein level of Notch1. Moreover, tideglusib reduced the cleavage of pro-apoptotic signal caspase proteins, including caspase 3 and caspase 9 following HI. ConclusionThese results indicate that tideglusib shows neuroprotection against hypoxic-ischemic brain injury in neonatal mice. General significanceTideglusib is a potential compound for the prevention or treatment of hypoxic-ischemic brain injury in neonates.

Long-term effects of cerebral hypoperfusion on neural density and function using misery perfusion animal model.

We investigated the chronic effects of cerebral hypoperfusion on neuronal density and functional hyperemia using our misery perfusion mouse model under unilateral common carotid artery occlusion (UCCAO). Neuronal density evaluated 28 days after UCCAO using [11C]flumazenil-PET and histology indicated no neurologic deficit in the hippocampus and neocortex. CBF response to sensory stimulation was assessed using laser-Doppler flowmetry. Percentage changes in CBF response of the ipsilateral hemisphere to UCCAO were 18.4 ± 3.0%, 6.9 ± 2.8%, 6.8 ± 2.3% and 4.9 ± 2.4% before, and 7, 14 and 28 days after UCCAO, respectively. Statistical significance was found at 7, 14 and 28 days after UCCAO (P < 0.01). Contrary to our previous finding (Tajima et al. 2014) showing recovered CBF response to hypercapnia on 28 days after UCCAO using the same model, functional hyperemia was sustained and became worse 28 days after UCCAO.

Stress-responsive heme oxygenase-1 isoenzyme participates in Toll-like receptor 4-induced inflammation during brain ischemia.

Toll-like receptors (TLRs) are involved in the progression of ischemic brain injury and hence vascular dementia; however, the underlying mechanisms are largely unknown. Here, we have investigated the interrelationship between stress-responsive heme oxygenase (HO)-1 isoenzyme and TLR4 during chronic brain hypoperfusion. The right unilateral common carotid artery occlusion was performed by ligation of the right common carotid artery in C57BL/6J mice. The brain cortex or hippocampus was removed for western blotting and confocal immunofluorescence analysis. The link between HO-1 and TLR4 was further examined by silencing TLR4 and pharmacological inhibition of HO-1 in primary cultured cortical neurons. Cognitive dysfunction and decrease in cerebral blood flow in mice were observed 4 weeks after the occlusion. Our data further show that common carotid artery occlusion induced an increase in TLR4 and HO-1 protein levels. Although the administration of CoPP (10 mg/kg), HO-1 agonist, improved the cognitive dysfunction in a mice model of occlusion, western blot analysis in primary cultured cortical neurons showed that HO-1 was upregulated after lipopolysaccharide treatment; this was partially abolished by the TLR4 siRNA interference. The flow cytometry analysis showed that pharmacological inhibition of HO-1 by ZnPP (100 μM) further exaggerated lipopolysaccharide-induced neuronal cell death. Hence, stress-responsive HO-1 isoenzyme participates in TLR4-induced inflammation during chronic brain ischemia. The pharmacological manipulation of TLR4 or the HO-1 antioxidant defense pathway may represent a novel treatment strategy for neuronal protection in vascular dementia.

Chronic cerebral hypoperfusion enhances Tau hyperphosphorylation and reduces autophagy in Alzheimer's disease mice.

Cerebral hypoperfusion and impaired autophagy are two etiological factors that have been identified as being associated with the development of Alzheimer’s disease (AD). Nevertheless, the exact relationships among these pathological processes remain unknown. To elucidate the impact of cerebral hypoperfusion in AD, we created a unilateral common carotid artery occlusion (UCCAO) model by occluding the left common carotid artery in both young and old 3xTg-AD mice. Two months after occlusion, we found that ligation increases phospho-Tau (p-Tau) at Serine 199/202 in the hippocampus of 3-month-old AD mice, compared to sham-operated AD mice; whereas, there is no change in the wild type (WT) mice after ligation. Moreover, cerebral hypoperfusion led to significant increase of p-Tau in both the hippocampus and cortex of 16-month-old AD mice and WT mice. Notably, we did not detect any change in Aβ42 level in either young or old AD and WT mice after ligation. Interestingly, we observed a downregulation of LC3-II in the cortex of aged AD mice and WT mice after ligation. Our results suggest that elevated p-Tau and reduced autophagy are major cellular changes that are associated with hypoperfusion in AD. Therefore, targeting p-Tau and autophagy pathways may ameliorate hypoperfusion-induced brain damage in AD.

Argon protects against hypoxic-ischemic brain injury in neonatal rats through activation of nuclear factor (erythroid-derived 2)-like 2.

Perinatal hypoxic ischaemic encephalopathy (HIE) has a high mortality rate with neuropsychological impairment. This study investigated the neuroprotective effects of argon against neonatal hypoxic-ischaemic brain injury.In vitro cortical neuronal cell cultures derived from rat foetuses were subjected to an oxygen and glucose deprivation (OGD) challenge for 90 minutes and then exposed to 70% argon or nitrogen with 5% carbon dioxide and balanced with oxygen for 2 hours.In vivo, seven-day-old rats were subjected to unilateral common carotid artery ligation followed by hypoxic (8% oxygen balanced with nitrogen) insult for 90 minutes. They were exposed to 70% argon or nitrogen balanced with oxygen for 2 hours. In vitro, argon treatment of cortical neuronal cultures resulted in a significant increase of p-mTOR and Nuclear factor (erythroid-derived 2)-like 2(Nrf2) and protection against OGD challenge. Inhibition of m-TOR through Rapamycin or Nrf2 through siRNA abolished argon-mediated cyto-protection. In vivo, argon exposure significantly enhanced Nrf2 and its down-stream effector NAD(P)H Dehydrogenase, Quinone 1(NQO1) and superoxide dismutase 1(SOD1). Oxidative stress, neuroinflammation and neuronal cell death were significantly decreased and brain infarction was markedly reduced. Blocking PI-3K through wortmannin or ERK1/2 through U0126 attenuated argon-mediated neuroprotection.These data provide a new molecular mechanism for the potential application of argon as a neuroprotectant in HIE.

Abstract TP221: A Novel Ultrasound Probe Attached to the Cervix Can Precisely Detect Large Patent Foramen Ovale

Introduction: We developed a novel probe (paste-able soft ultrasound probe; PSUP) attached to the cervix for detection of right-to-left shunt (RLS), because insufficient temporal bone window interrupts the precise examination for diagnosis of RLS. Hypothesis: We assessed the hypothesis that diagnostic ability of PSUP for RLS detection is equal to those of transesophageal echocardiography (TEE). Methods: Subjects were patients with ischemic stroke and transient ischemic attack who underwent TEE. PSUP was a 2.0-MHz center frequency, which had an equal property with TCD, and the shape was thin, soft, and square modified for attachment to the neck. At first, we performed TEE with the echoscope at the level of the fossa ovalis after injection of saline agitated with air in the right antecubital vein. The procedure was performed with and without Valsalva maneuver. Visualization of microembolic signals (MES) induced contrast agent within the right atrium and crossing the interatrial septum was considered as positive patent foramen ovale (PFO). We divided PFO into two groups according to number of MES, such as small PFO (1-29 of MES) and large PFO (≥30 of MES). Then, monitoring using PSUP was performed at unilateral common carotid artery (CCA) using similar preparation and procedure to TEE. RLS by PSUP diagnosed when we found 1and more MES in CCA. We compared detectable rate by size of PFO between TEE and PSUP, and calculated accuracy of PSUP against TEE. Results: From May 2014 to July 2015, 62 patients (46 male, mean age of 61 years) were included in this study. We diagnosed 26 of 62 patients (42%) as PFO by TEE, whereas PSUP detected in 17 of them (27%). As a reference of TEE findings, diagnostic ability of PSUP was 58% of sensitivity, 94% of specificity, and 79% of accuracy. In TEE examination, large PFO was 11 patients and small was 15 patients. PSUP could evaluate large PFO (9 of 11 patients) more accurately than small one (6 of 15, 82% vs. 40%, p=0.05). Conclusion: PSUP should have a considerable accuracy of large PFO diagnosis. For patients with insufficient temporal bone window, PSUP may play an important role of detecting large PFO.

Protective effects of carnosine on white matter damage induced by chronic cerebral hypoperfusion.

Carnosine is a dipeptide that scavenges free radicals, inhibits inflammation in the central nervous system, and protects against ischemic and hypoxic brain damage through its anti-oxidative and anti-apoptotic actions. Therefore, we hypothesized that carnosine would also protect against white matter damage caused by subcortical ischemic injury. White matter damage was induced by right unilateral common carotid artery occlusion in mice. The animals were treated with 200, 500 or 750 mg/kg carnosine by intraperitoneal injection 30 minutes before injury and every other day after injury. Then, 37 days later, Klüver-Barrera staining, toluidine blue staining and immunofluorescence staining were performed. Carnosine (200, 500 mg/kg) substantially reduced damage to the white matter in the corpus callosum, internal capsule and optic tract, and it rescued expression of myelin basic protein, and alleviated the loss of oligodendrocytes. However, carnosine at the higher dose of 750 mg/kg did not have the same effects as the 200 and 500 mg/kg doses. These findings show that carnosine, at a particular dose range, protects against white matter damage caused by chronic cerebral ischemia in mice, likely by reducing oligodendroglial cell loss.

Effects of Puerarin Derivative P on Learning, Memory and MPO Activity in Vascular Dementia Model Mice

Pharmacological experiments confirmed that Puerarin could not only expand the arterial vessels, increase the local blood flow, but also could protect the myocardium, improve the blood supply of ischemic tissue, which was used to treat the cerebrovascular dementia disease in clinical practice. Its own structure particularity caused the lower bioavailability and poorer solubility. In order to improve the deficiency, the related pharmacological experiments of the newly synthesized puerarin derivative (P), so as to expect the better curative effect than puerarin in the process of treating vascular dementia. The vascular dementia model was established by permanently ligating the common carotid artery in mice. The effects of puerarin derivative (P) on learning and memory in mice by water maze, Y maze and new object discrimination methods; The myeloperoxidase activity in the ischemic cerebral cortex was evaluated in mice by biochemical method. The experimental results showed that the mice spontaneous alternation response accuracy in Y maze could be obviously improved in 100mg/kg puerarin derivative group; In water maze, the swimming time to the safe platform would be significantly decreased in puerarin derivative group. Meanwhile, the MPO activity in the cerebral cortex of dementia mice was significantly decreased in 100mg/kg puerarin derivative group by permanently ligating the unilateral common carotid artery.