Clamping Of Common Carotid Arteries Research Articles

Effects of hydroxyapatite extract on rats with transient ischemia: Long-term potentiation and axon regeneration.

Hydroxyapatite (HA) has been extensively used as a reconstructive and prosthetic material for osseous tissue. The present study aimed to determine whether HA extract exerted effects on central nervous system injury following transient cerebral ischemia/reperfusion in rats. Male Wistar rats were treated with HA following bilateral common carotid artery clamping (two-vessel occlusion). The results demonstrated that treatment with HA extract attenuated the inhibition of long-term potential in a rat model of transient cerebral ischemia/reperfusion. Furthermore, HA extract improved axon regeneration, which was confirmed via the immunohistochemical analysis of growth associated protein 43 and glial fibrillary acidic protein. Taken together, the results of the present study provided preliminary evidence of the protective effect of HA on neuronal damage.

Identification of the stroke type of hemorrhage and ischemic based on microwave measurement technique

Objective To establish a microwave scattering parameter acquisition system to detect cerebral hemorrhage and cerebral ischemia animal models, and to study the non-contact rapid identification methods for the two stroke types. Methods Rabbits were selected for modeling. Eight rabbits in the cerebral hemorrhage group were injected with autologous blood. Six rabbits in the cerebral ischemia group were treated with bilateral common carotid artery clamping and femoral artery bleeding. The measurement excitation source has a scanning frequency range of 300 kHz to 3 GHz and an intermediate frequency bandwidth of 30 kHz. The signal of the S21 phase was acquired. The collected microwave scattering signals were subjected to mean filtering, principal component analysis dimension reduction, and mean clustering and nearest neighbor analysis to realize the identification of stroke types. Results The microwave scattering measurement method can reflect the changes of cerebral hemorrhage and cerebral ischemia. The phase of S21 decreases with the increase of blood loss and increases with the increase of ischemic duration. The results of the differential experiment showed that all 14 models were correctly identified. Conclusions The stroke identification system based on microwave scattering measurement can effectively distinguish rabbit cerebral hemorrhage model and ischemic model. This technology is low cost, portable non-invasive, simple operation and fast, which make it be a promising method for identifying pre-hospital stroke types. Key words: Stroke types diagnosis; Cerebral hemorrhage; Cerebral ischemia; Microwave detection; Non-contact diagnosis

Cerebral watershed infarcts may be induced by hemodynamic changes in blood flow

Objectives: A watershed infarct is defined as an ischemic lesion at the border zones between territories of two major arteries. The pathogenesis of watershed infarcts, specifically whether they are caused by hemodynamic or embolic mechanisms, has long been debated. In this study, we aimed to examine whether watershed infarcts can be induced by altering the hemodynamic conditions in rats.Materials and Methods: In phase one, to determine the proper clamping duration for a reproducible infarct, 30 rats were equally divided into 5 subgroups and underwent bilateral common carotid artery (CCA) clamping for different durations (0.5, 1.0, 1.5, 2.0, and 3.0 hours). In phase two, to analyze the types of infarcts induced by bilateral CCA clamping, 40 rats were subjected to bilateral CCA clamping for 2 hours. As a control, 8 rats underwent all the operation procedures except bilateral CCA clamping. We performed 7.0T magnetic resonance imaging on the surviving rats on the second day to evaluate the extent of the infarcts. We further identified and examined the infarcts with brain slices stained using 2, 3, 5-triphenyltetrazolium chloride (TTC) on the third day.Results: After 2 hours of bilateral CCA clamping, cerebral infarction occurred in 42% of surviving rats (13/31). The majority of the ischemic lesions were located in watershed regions of the brain, demonstrated by both MRI and TTC staining.Conclusion: Watershed infarcts were induced through changing hemodynamic conditions by bilateral CCA clamping in rats. This method may lead to the development of a reliable rodent model for watershed infarcts.

How to Clamp and Bypass if There Is Single Artery Supply to the Head and That Contains Severe Stenosis?

Takayasu arteritis manifests with arterial occlusions and aneurysms. Revascularization is sometimes challenging, especially when carotid arteries are affected. In this report, we present a carotid artery revascularization technique in a patient who was admitted with orthostatic and postprandial transient ischemic attacks, resulting in a diagnosis of bilaterally occluded subclavian and vertebral arteries, occluded left common carotid artery, and severely stenosed right common carotid artery. Clamping of the right carotid artery was a challenge; however, our technique provides a neurologically safe revascularization.

P-glycoprotein expression in brain during ischemia-reperfusion

On wistar rats expression of P-glycoprotein in the brain after unilateral occlusion-reperfusion of the common carotid artery was studied. Correlation between the expression of the transporter and redox status of the brain cerebral cortex was assessed. Occlusion was simulated under ether anesthesia by common carotid artery clamping using vascular clamp for 180 minutes followed by recanalization. Samples of cerebral cortex were taken after 60 min, 4 h, 24 h, 5 days and 14 days after reperfusion and subjected to standard immunohistochemical processing, as well as evaluating the redox status. It was revealed that the 180-minute occlusion of unilateral common carotid artery followed by reperfusion causes a decrease in the expression of P-glycoprotein after 60 min and 4 hours after reperfusion by 52,5% и 63,1% (p0,05) respectively. P-glycoprotein expression is conversely related with the level of TBA-reactive species.

Neuroprotective effects of a glutathione depletor in rat post-ischemic reperfusion brain damage.

The induction of heme oxygenase (HO), the rate-limiting enzyme in heme degradation, occurs as an adaptative response to oxidative stress and is consequent to decrease in cellular glutathione levels. Our previous studies demonstrated significant increase in survival rates of rats treated with glutathione depletors and submitted to transient cerebral ischemia. The aim of the present research was to test the effects of L-Buthionine sulfoximine (BSO), a glutathione depletor, during cerebral post-ischemic reperfusion. Cerebral ischemia was induced by bilateral clamping of common carotid arteries for 20 min. Each sample was used for glutathione ad lipid peroxidation level dosage and for evaluating the expression of heme oxygenase both after a single subcutaneous administration of BSO and without treatment. In the same experimental conditions, endothelial, inducible and neuronal Nitric Oxide Synthase (eNOS, iNOS and nNOS) and Dimethylarginine Dimethyl amine Hydrolases (DDAH-1 and DDAH-2) were also evaluated. Results obtained in the present study suggested that HO-1 over-expression may be implicated in the protective effect of BSO in post-ischemic reperfusion brain damage, although the involvement of other important stress mediators cannot be ruled out.

The effects of levosimendan on brain metabolism during initial recovery from global transient ischaemia/hypoxia

BackroundNeuroprotective strategies after cardiopulmonary resuscitation are currently the focus of experimental and clinical research. Levosimendan has been proposed as a promising drug candidate because of its cardioprotective properties, improved haemodynamic effects in vivo and reduced traumatic brain injury in vitro. The effects of levosimendan on brain metabolism during and after ischaemia/hypoxia are unknown.MethodsTransient cerebral ischaemia/hypoxia was induced in 30 male Wistar rats by bilateral common carotid artery clamping for 15 min and concomitant ventilation with 6% O2 during general anaesthesia with urethane. After 10 min of global ischaemia/hypoxia, the rats were treated with an i.v. bolus of 24 μg kg-1 levosimendan followed by a continuous infusion of 0.2 μg kg-1 min-1. The changes in the energy-related metabolites lactate, the lactate/pyruvate ratio, glucose and glutamate were monitored by microdialysis. In addition, the effects on global haemodynamics, cerebral perfusion and autoregulation, oedema and expression of proinflammatory genes in the neocortex were assessed.ResultsLevosimendan reduced blood pressure during initial reperfusion (72 ± 14 vs. 109 ± 2 mmHg, p = 0.03) and delayed flow maximum by 5 minutes (p = 0.002). Whereas no effects on time course of lactate, glucose, pyruvate and glutamate concentrations in the dialysate could be observed, the lactate/pyruvate ratio during initial reperfusion (144 ± 31 vs. 77 ± 8, p = 0.017) and the glutamate release during 90 minutes of reperfusion (75 ± 19 vs. 24 ± 28 μmol·L-1) were higher in the levosimendan group. The increased expression of IL-6, IL-1ß TNFα and ICAM-1, extend of cerebral edema and cerebral autoregulation was not influenced by levosimendan.ConclusionAlthough levosimendan has neuroprotective actions in vitro and on the spinal cord in vivo and has been shown to cross the blood–brain barrier, the present results showed that levosimendan did not reduce the initial neuronal injury after transient ischaemia/hypoxia.

L-3-n-butylphthalide improves cognitive deficits in rats with chronic cerebral ischemia

3-n-Butylphthalide (NBP) has been shown to have protective effects against ischemic stroke. In the present study, we investigated effects of l-3-n-butylphthalide (l-NBP) on the learning and memory impairment induced by chronic cerebral ischemia in rats. Male Wistar rats were administered 20 mg/kg l-NBP by gavage daily for 30 days after the bilateral common carotid artery clamping (two-vessel occlusion, 2-VO). Results showed that daily treatments of 20 mg/kg l-NBP significantly attenuated spatial learning deficits in Morris water maze (MWM) task. Results of long-term potentiation (LTP) indicated that treatment with 20 mg/kg l-NBP attenuated the inhibition of LTP in rat model of 2-VO. Moreover, l-NBP reduced glial fibrillary acidic protein (GFAP)-positive astrocytes induced by chronic cerebral ischemia. The present findings demonstrate the protective effect of l-NBP on chronic cerebral ischemia-induced hippocampus injury, which supports using l-NBP for therapy of cerebral ischemia in the future.

Effect of Treatment with Cyanidin-3-O-β-D-Glucoside on Rat Ischemic/Reperfusion Brain Damage

This study investigated the effect of cyanidin-3-O-β-glucoside on an experimental model of partial/transient cerebral ischemia in the rats in order to verify the effectiveness of both pre- and posttreatments. Cyanidin-3-O-β-glucoside-pretreated rats were injected with 10 mg/Kg i.p. 1 h before the induction of cerebral ischemia; in posttreated rats, the same dosage was injected during reperfusion (30 min after restoring blood flow). Cerebral ischemia was induced by bilateral clamping of common carotid arteries for 20 min. Ischemic rats were sacrificed immediately after 20 min ischemia; postischemic reperfused animals were sacrificed after 3 or 24 h of restoring blood flow. Results showed that treatment with cyanidin increased the levels of nonproteic thiol groups after 24 h of postischemic reperfusion, significantly reduced the lipid hydroperoxides, and increased the expression of heme oxygenase and γ-glutamyl cysteine synthase; a significant reduction in the expression of neuronal and inducible nitric oxide synthases and the equally significant increase in the endothelial isoform were observed. Significant modifications were also detected in enzymes involved in metabolism of endogenous inhibitors of nitric oxide. Most of the effects were observed with both pre- and posttreatments with cyanidin-3-O-β-glucoside suggesting a role of anthocyanin in both prevention and treatment of postischemic reperfusion brain damage.

The effects of desflurane on delayed neuronal injury after transient forebrain ischemia in the rat.

Volatile anesthetics have been shown protective against focal or global cerebral ischemia in animal models. However isoflurane failed to provide persistent protection because of late onset of apoptosis after ischemia. The aim of this study was to elucidate the effects of desflurane on delayed neuronal damage after forebrain ischemia. Rats were divided into 2 groups and anesthetized with desflurane or isoflurane. Forebrain ischemia was produced by both induced hypotension and 10 minutes of common carotid artery clamping. After 2 days and 2 weeks, rats were killed under anesthesia and brains were removed for Western blot analysis of Bcl-2, Bax, and caspase 3 expression and histopathologic study. The apoptotic cell numbers in hippocampal CA1 area were increased after 2 weeks, and there was no significant difference between groups. There was no significant difference in caspase 3 expression between groups. The Bax/Bcl-2 ratio was increased at 2 weeks after ischemia, and there was no significant difference between group. The data indicate that desflurane also delays but does not prevent the neuronal injury caused by ischemia. Desflurane reduced the development of apoptosis early after ischemia but did not prevent it at later stages of post-ischemic recovery.

Extracellular Diffusion Parameters in the Rat Somatosensory Cortex during Recovery from Transient Global Ischemia/Hypoxia

Changes in the extracellular space diffusion parameters during ischemia are well known, but information about changes during the postischemic period is lacking. Extracellular volume fraction (alpha) and tortuosity (lambda) were determined in the rat somatosensory cortex using the real-time iontophoretic method; diffusion-weighted magnetic resonance imaging was used to determine the apparent diffusion coefficient of water. Transient ischemia was induced by bilateral common carotid artery clamping for 10 or 15 mins and concomitant ventilation with 6% O(2) in N(2). In both ischemia groups, a negative DC shift accompanied by increased potassium levels occurred after 1 to 2 mins of ischemia and recovered to preischemic values within 3 to 5 mins of reperfusion. During ischemia of 10 mins duration, alpha typically decreased to 0.07+/-0.01, whereas lambda increased to 1.80+/-0.02. In this group, normal values of alpha=0.20+/-0.01 and lambda=1.55+/-0.01 were registered within 5 to 10 mins of reperfusion. After 15 mins of ischemia, alpha increased within 40 to 50 mins of reperfusion to 0.29+/-0.03 and remained at this level. Tortuosity (lambda) increased to 1.81+/-0.02 during ischemia, recovered within 5 to 10 mins of reperfusion, and was increased to 1.62+/-0.01 at the end of the experiment. The observed changes can affect the diffusion of ions, neurotransmitters, metabolic substances, and drugs in the nervous system.

Transcranial Doppler Monitoring of Transcervical Carotid Stenting With Flow Reversal Protection

Transfemoral carotid stenting, despite becoming very frequent, has some limitations such as difficult groin access in few patients, lack of distal protection during filter placement, or embolization despite protection. Transcervical stenting (TCS) is a novel technique during which a common carotid to jugular vein shunt is placed creating a protective reversal flow in the internal carotid artery after proximal common carotid artery (CCA) clamping. We aim to study, with transcranial Doppler (TCD), cerebral flow changes and microemboli detection during transcervical stenting. From September 2005 to March 2006, of 65 consecutive patients eligible for carotid revascularization, 23 were considered high risk (sapphire criteria) and underwent TCS. Neurologic examination was performed before and after the procedure by a neurologist and a preprocedure vascular reactivity TCD examination was done in all patients. After CCA clamping, flow inversion was observed in the anterior cerebral artery, supplying blood to the middle cerebral artery (MCA) and internal carotid artery (reversal). TCD did not detect any air/solid emboli during stent deployment and angioplasty confirming the reversal flow protection hypothesis. Mean reversal flow time was 15.4 minutes; in all cases, substantial MCA flow was present during CCA clamping (initial mean velocity 30 cm/s), and a slow gradual increase was observed traducing collateral flow recruitment (mean velocity after 5 minutes 36 cm/s, P<0.001). Flow increase was observed in all patients except in those with preprocedural exhausted ipsilateral vascular reactivity (16% versus 2%, P=0.036). The only in-procedure complication was one transient ischemic attack. After CCA unclamping, normal antegrade flow was restored in anterior cerebral artery and mean final MCA velocity increased 16% according to preprocedure flow. TCS with protective internal carotid artery flow reversal can eliminate showers of micoremboli during stent deployment making it a promising carotid revascularization technique in high-risk patients with carotid stenosis.

The Effects of Propofol and Sevoflurane on Neuronal Apoptosis and Bcl-2 Family Protein Expression after Transient Forebrain Ischemia in the Rat

Background: Anesthetic preconditioning and anesthetics itself have been known to prevent ischemic injury in brain and heart. The purpose of this study was to evaluate the effects of anesthetics and anesthetic preconditioning on neuronal apoptosis and Bcl-2 family protein expression in transient forebrain ischemia. Methods: Rats were divided into 3 groups and anesthetized with intraperitoneal propofol (P group) or sevoflurane (S and SP groups). In SP group, rats were anesthetized with sevoflurane during 30 minutes and then anesthesia was maintained with intraperitoneal propofol. Forebrain ischemia was produced by both induced hypotension and 10 minutes of common carotid artery clamping. Results: At 2 days after ischemia, the numbers of necrotic cells in hippocampal CA1 area in S group were less than P and SP groups, and the number of apoptotic cells in S and SP groups were less than P group. The expressions of Bcl-xl in P and SP groups were less than S group. The expression of Bax in P group was less than S and SP groups. At 2 weeks after ischemia, the numbers of necrotic cells in hippocampal CA1 area in S and SP groups were less than P group, and the numbers of apoptotic cells in S group were less than P and SP groups. The expressions of Bcl-xl in S group were more than P and SP groups. Conclusions: Sevoflurane could reduce ischemic injury during transient forebrain ischemia. However the anesthetic preconditioning with sevoflurane could not help to prevent delayed neuronal apoptosis after forebrain ischemia.

Cerebrovascular reactivity: rat studies in rheoencephalography

Here we describe a correlative study of cerebral blood flow (CBF) using global, local CBF and carotid flow measurements. The primary objective of this study was to establish a relationship between REG and CBF autoregulation. Rheoencephalography (REG), a rarely used method to measure CBF, is a potential tool of non-invasive continuous life sign monitoring and detection of early cerebrovascular alteration. However, the anatomical background of REG is not clearly understood. Two experimental studies were undertaken on anesthetized rats to define two CBF measurements: (1) CO2 inhalation, and, (2) clamping of common carotid arteries. Measurement of CBF was taken with REG, laser Doppler flowmetry (LDF) and carotid flow by Doppler ultrasound. Data were off-line processed. During CO2 inhalation, the increases in REG and LDF were significant (p = 0.0001), while carotid flow and systemic arterial pressure decreased. During carotid artery clamping, the decrease in REG and Doppler ultrasound was significant (p = 0.0001). REG showed cerebrovascular reactivity, indicating the relationship to arteriolar changes. Compared to LDF and carotid flow, only REG showed the classical CBF autoregulation.

The effect of CGP-40116 on pilocarpine evoked seizures in mice exposed to transient episode of brain ischemia

The objective of the study was to examine the role of N-methyl- d-aspartate (NMDA) receptors in the modulation of a brain tolerance after a transient cerebral ischemia. Adult mice were exposed for 30 min to bilateral clamping of common carotid arteries (BCCA) under anaesthesia. The competitive NMDA antagonist CGP-40116 was administered intraperitoneally (i.p.) in two experimental paradigms, (a) acute treatment: twice, 4.0 mg/kg; 1.5 h before the clamping of vessels and 6 h after re-circulation and (b) chronic treatment in a dose of 1.0 mg/kg; started 24 h after re-circulation and continued once daily for 13 days with the last injection 24 h before the induction of convulsions. Seizures were evoked with pilocarpine (400 mg/kg, i.p.) 14 days after BCCA. The preliminary study showed that BCCA induced protection against pilocarpine toxicity. The acute treatment with CGP-40116 partially diminished the anticonvulsant phenomenon. In contrast, the chronic treatment with the drug led to a marked potentiation of the effect. The whole brain γ-aminobutyric acid (GABA) analysis performed 14 days after BCCA showed a moderate increase in vehicle-treated mice and a significant elevation after chronic treatment with CGP-40116. It can be concluded that NMDA antagonists may exert the opposite effects on the brain tolerance against pilocarpine toxicity after BCCA. The acute treatment with CGP-40116 diminished its induction while the chronic low-dose treatment enhanced a brain tolerance, possibly through the mechanism of chemical preconditioning.

INFLUENCES OF GABA RECEPTOR SUBTYPES ON NEUROPROTECTIVE ACTION OF PROPOFOL USING MONGOLIAN GERBIL BRAIN ISCHEMIC MODEL

S465 Introduction: It might be possible to explain that the neuroprotective mechanisms of intravenus anesthetics, relate to the potentiation of the gamma-amino butyric acid (GABA) neurons, since barbiturates and benzodiazepines (BZP) bind to the GABAa/BZP receptor complex and stimulate the Cl- influx to the neuronal cells. In the neurochemical studies, the physiological properties of GABA receptor subtypes in the central nervous system (CNS) have been identified. In particular, the different localization between GABAa and GABAb receptors in the neuronal system might be linked to their dissimilar physiological functions appeared in CNS. In this presentation, using the pathopharmacological techniques, we examined the neuroprotective effects of propofol on the brain ischemia of Mongolian gerbil and the functional role of GABA receptor subtypes on the neuroprotective mechanism of propofol. Materials and Methods: The male Mongolian gerbils (body weight; 50-80g) were anesthetized with 1.0% isoflurene and 70% N2O in O2. Each drug was injected intraperitoneal at 15 min before the treatment of ischemia. Under the anesthesia. the brain ischemia was induced by bilateral common carotid artery clamping (2VO) for 4 min. During brain ischemia and recovery from anesthesia, both temperatures of brain and body were kept at 37[degree sign]C by means of heating lamps. One week after ischemia, the ischemic animals were reanesthetized and perfusion-fixed with 4% formaldehyde, and these brains were dissected for the preparations of pathological estimations. The score of pathological estimation detected in the hippocampal CA1 area was divided for five grades depending on the severity. The following drugs were used in this experiment; propofol (25 and 50 mg/kg), muscimol (GABAa agonist; 0.5-4 mg/kg), bicuculline (GABAa antagonist; 5, 7.5 mg/kg), baclofen (GABAb agonist; 2, 4mg/kg) and phaclofen (GABAb antagonist; 1.5, 3mg/kg). Results: 1) One week after brain ischemia induced by a 4 min-2VO, more than 90 % of neuronal cells in CA1 region of hippocampus were injured, and the degenerated cells and vacuolarized cells were appeared in most cases. 2) The pretreatment of propofol significantly attenuated the brain injury induced by 2VO in a dose-dependent manner. The pretreatment of muscimol reduced the number of cell injury and improved the severe conditions in a dose-dependent manner, although this neuroprotection is less potent compared to that of propofol. However it was so hard to detect the significant neuronal protection after the pretreatment of baclofen. 3) The neuroprotecitive effects of propofol was attenuatedby the coadministration of bicuculline, but not phaclofen. Discussion: Our results indicate that propofol and GABAa receptor agonist suppress the severity of brain injury after 2VO, and then GABAa antagonists block these neuronal protections. These results, taken together with others [1,2,3] suggest that delayed neuronal death induced by ischemia may be partially modulated by the inhibition and/or attenuation of GABAa receptor activity and that the pharmacological mechanism of propofol may involve the potentiation of GABAa receptor.

MAP2, synaptophysin immunostaining in rat brain and behavioral modifications after cerebral postischemic reperfusion.

Plasticity in the central nervous system after cerebral ischemia is a controversial issue; focal cerebral ischemia produces an area of infarction that is surrounded by neurons that may respond to nearby damage by creating new synapses. In the present study the expression of the postsynaptic microtubule-associated protein 2 (MAP2) and the presynaptic marker protein, synaptophysin, was investigated by immunocytochemical techniques in the CA1 sector of hippocampus and in cerebellum of rats made ischemic by bilateral clamping of common carotid arteries and reperfused for 7 and 30 days. In addition, ischemia-induced behavioral alterations were also evaluated after 7 and 30 days of reperfusion. The present study demonstrates a decreased postsynaptic MAP2 immunoreactivity, representative of neuronal loss, particularly in CA1 sector of hippocampus and in cerebellum of ischemic rats reperfused for 7 days. After 30 days of reperfusion, MAP2 immunostaining was similar to control. In the same brain sections an increased presynaptic synaptophysin immunoreactivity has been observed only after 30 days of reperfusion. These data suggest compensatory regenerative changes associated with synaptic remodelling and are supported by behavioral recovery observed under the same experimental conditions.