Cortical Aquaporin-4 in relation to brain oedema and neurological function of cortical cryo-injured mice

To estimate the spatial and temporal expression of Aquaporin-4 (AQP-4) in a murine model of automated cerebral cryoinjury and correlate AQP-4 expression with development of brain oedema and neurological function. AQP-4 levels were determined quantitatively by Western blots at site of injury and at sites adjacent to and distant from injury in brains of cryoinjured (experimental) (n = 18), sham injured (n = 18) & normal mice at 24, 48, 72 h post injury. AQP-4 expression was correlated with percentage water content of brain, Neurological Severity Score (NSS) and rotarod scores. We found a 1.4-fold increase in expression of AQP-4 at the site of injury and at sites distant from injury at 24 h when compared to normal mice (p = 0.05). The increase in expression of AQP-4 24 h post injury was significantly higher in experimental group at the site of injury and at the site adjacent to the injury in the ipsilateral hemisphere when compared to the sham injured mice (p = 0.05). At 24 h post injury the median NSS score in the experimental group was 9 (interquartile range 7.25–10) and that in the sham group was 0.5 (interquartile range 0.0–1.0) (p < 0.001).At 48 and 72 h, AQP-4 expression remained elevated in the experimental group when compared to normal brain, but the levels were not significantly different from that in sham group. AQP-4 expression was significantly elevated in the ipsilateral hemisphere in the first 24 h following cerebral cortical injury in mice and this could be correlated with worsening of neurological function. Over the next 48 h, there was a trend towards decrease in AQP-4 expression that was associated with partial recovery of neurological function.     

Post-ischemic hypothermia for 24 h in P7 rats rescues hippocampal neuron: Association with decreased astrocyte activation and inflammatory cytokine expression

Hypothermia is an effective method for reducing the neuronal damage induced by hypoxia–ischemia (HI) but the underlying mechanism remains unclear. To investigate the effects of post-HI hypothermia on the developing brain, 7-day-old rats were subjected to left carotid artery ligation followed by 8% oxygen for 2 h. They were divided into a hypothermia group (rectal temperature 32–33 °C for 24 h) and a normothermia group (36–37 °C for 24 h) immediately after hypoxia–ischemia. Animals were sacrificed at 12, 24 and 72 h for gene analysis and 0, 1, 3 and 7 days for protein analysis after HI. There was a significant decrease in infarct volume in the hypothermia group at 7 days after HI compared with that in the normothermia group. The hypothermia group had more neuronal nuclei (NeuN) positive neurons and lower levels of glial fibrillary acidic protein (GFAP) mRNA and immunoreactivity in the hippocampus CA1 region than the normothermia group. Real-time PCR showed no significant difference in glial cell line-derived neurotrophic factor (GDNF) mRNA expression in the hippocampus in the two groups at various time points after HI. However, GDNF protein level was significantly increased in the hypothermia group. On the other hand, mRNA and protein levels of the inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) were dramatically decreased in the hypothermia compared with the normothermia group. The present findings highlight an apparent association between inhibition of hippocampal neuron loss by hypothermia and decreased astrocytosis and inflammatory cytokine release after hypoxia–ischemia in the developing brain.     

Changes in the NPY immunoreactivity in gerbil hippocampus after hypoxic and ischemic preconditioning

Preconditioning with sublethal ischemia or hypoxia may reduce the high susceptibility of CA1 pyramidal neurons to ischemic injury. In this study, we tested the hypothesis that enhanced level of neuropeptide Y (NPY) might play a role in the mechanisms responsible for this induced tolerance. Changes in NPY immunoreactivity in the hippocampal formation of preconditioned Mongolian gerbils were compared with the level of tolerance to test ischemia. Tolerance was induced by preconditioning with 2-min of ischemia or with three trials of mild hypobaric hypoxia (360 Torr, 2 h), separated by 24 h, that were completed 48 h before the 3-min test ischemia. The number of NPY-positive neurons in the gerbil hippocampal formation was assessed 2, 4 and 7 days after preconditioning. Survival of the CA1 pyramidal neurons was examined 14 days after the insult. Our experiments demonstrated that ischemic and hypoxic preconditioning produced equal attenuation of the damage evoked by 3-min ischemia, although the pattern of NPY immunoreactivity in the hippocampus differed. Preconditioning ischemia resulted in a 20% rise in the number of NPY-positive neurons 2 days later that disappeared 4 days after the ischemic episode, while mild hypobaric hypoxia induced a twofold increase in the number of NPY-positive neurons that lasted for at least 7 days. Although induced tolerance to ischemia 2 days after ischemic or hypoxic preconditioning was accompanied by increased immunoreactivity of NPY, there was no correlation between its intensity and the level of neuroprotection.     

Ischemic preconditioning-induced neuroprotection against transient cerebral ischemic damage via attenuating ubiquitin aggregation

Ubiquitin binds to short-lived proteins, and denatured proteins are produced by various forms of injuries. In the present study, we investigated the effect of ischemic preconditioning (IPC) on free ubiquitin and its mutant form (ubiquitin^+ 1) in the gerbil hippocampus induced by transient cerebral ischemia. The animals were randomly assigned to 4 groups (sham-operated-group, ischemia-operated-group, IPC plus (+)-sham-operated-group, and IPC + ischemia-operated-group). IPC was induced by subjecting gerbils to a 2 min of ischemia followed by 1 day of recovery. A significant loss of neurons was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) in the ischemia-operated-groups 5 days after ischemia–reperfusion (I–R). In all the IPC + ischemia-operated-groups, neurons in the SP were well protected. We found that strong ubiquitin immunoreactivity was detected in the SP in the sham-operated-group and the immunoreactivity was decreased with time after I–R. In all the IPC + ischemia-operated-groups, ubiquitin immunoreactivity in the SP was similar to that in the sham-operated group. Moderate ubiquitin^+ 1 immunoreactivity was detected in the SP of the sham-operated-group, and the immunoreactivity was markedly increased 2 days after I–R. Five days after I–R, ubiquitin^+ 1 immunoreactivity was very weak in the SP. In all the IPC + ischemia-operated-groups, ubiquitin^+ 1 immunoreactivity in the SP was slightly decreased with time after I–R. Western blot analysis showed that, in all the IPC + ischemia-ischemia-groups, the levels of ubiquitin and ubiquitin^+ 1 proteins were well maintained after I–R. In brief, our findings suggest that the inhibition of the depletion of free ubiquitin and the formation of ubiquitin^+ 1 may have an essential role in inducing cerebral ischemic tolerance by IPC.     

Monosialotetrahexosy-1 ganglioside attenuates diabetes-associated cerebral ischemia/reperfusion injury through suppression of the endoplasmic reticulum stress-induced apoptosis

We aimed to assess the neuroprotective mechanism of monosialotetrahexosy-1 ganglioside (GM1) on focal cerebral ischemia/reperfusion (I/R) injury in rats with diabetes. A total of 54 male Wistar rats were induced with diabetes mellitus by administration of streptozotocin (STZ). The rats were then randomized into three groups, including sham group (n = 18), I/R group (n = 18), and GM1 group (n = 18). Focal cerebral ischemia was modeled using the right middle cerebral artery occlusion method. In the GM1 group, diabetic rats were intraperitoneally administered with GM1 (15 mg/kg) at 20 min prior to reperfusion. GM1 was replaced by an equal volume of saline in the I/R group. Rats from the sham group accepted sham operation and normal saline. The neurological deficit and brain infarct volume and TUNEL-apoptosis were evaluated. The expression of endoplasmic reticulum (ER) stress-related proteins, including caspase-12, GRP78 and CHOP/GADD153, was examined by Western blot. GM1 notably reduced the cerebral infarct size and improved the neurological behavior. In addition, GM1 dramatically reduced TUNEL-positive cell numbers in the cerebral cortex. Furthermore, GM1 treatment modulated protein levels, increasing GRP78 and reducing CHOP/GADD153 expression along with activation of caspase-12 in the ischemic brain hemispheres. These results imply that GM1 attenuates diabetes-associated cerebral I/R injury by suppressing the ER stress-induced apoptosis.     

Transient ischemia-induced change of CCR7 immunoreactivity in neurons and its new expression in astrocytes in the gerbil hippocampus

Chemokines and their receptors are important players in organism homeostasis, development and immune response to inflammatory stimuli. In the present study, we examined effects of ischemia-reperfusion injury on the immunoreactivity and protein levels of chemokine C–C motif receptor 7 (CCR7) in the gerbil hippocampus (CA1–3 regions) after 5 min of transient global cerebral ischemia. CCR7 immunoreactivity was dramatically changed in the pyramidal neurons of the CA1, not CA2/3, region after ischemia-reperfusion. The immunoreactivity was increased after ischemia-reperfusion, and it was barely found from 5 days post-ischemia. In addition, CCR7 immunoreactivity was newly expressed in astrocytes, not microglia, in the ischemic CA1 region from 5 days post-ischemia. However, we did not observe this finding in the ischemic CA2/3 region. Furthermore, CCR7 protein levels in the ischemic CA1 region were changed like the change pattern of its immunoreactivity. These results indicate that both CCR7 immunoreactivity and protein levels are distinctively altered only in the CA1 region after transient cerebral ischemia and that the changes in CCR7 expression may be related to the ischemia-induced delayed neuronal death.     

Increased serum S100B concentration correlates with hippocampal S100B overexpression and cellular damage following chronic cerebral hypoperfusion

To develop a sensitive and convenient clinical index of brain injury, we investigated the relationship between serum S100B concentration and the expression of S100B in the hippocampus at multiple time points following permanent ligation of the bilateral common carotid artery (2vo). Ninety Sprague–Dawley rats were divided into a control group (n = 6), model group (n = 42), and sham operation (SO) group (n = 42). The model group was subjected to permanent 2vo ligation, while the bilateral common carotid artery was isolated but not ligated in SO group rats. A control group received no treatment. The SO and model groups were divided into 7 subgroups of six rats each examined at 6, 12, 24, 48, or 72 h, as well as 7 and 14 d after treatment. Dynamic changes in serum S100B concentration was measured by ELISA, the S100B mRNA expression in hippocampus by RT-PCR, and hippocampal CA1 S100B protein expression by immunohistochemistry. The degeneration of neurons during chronic cerebral hypoperfusion was well correlated with the elevation of serum S100B, as well as with hippocampal S100B mRNA expression and S100B protein overexpression in the hippocampal CA1. Thus, serum S100B concentration during chronic cerebral hypoperfusion reflects the extent and progression of brain injury.     

Plasma-derived and recombinant C1 esterase inhibitor: Binding profiles and neuroprotective properties in brain ischemia/reperfusion injury

C1 esterase inhibitor (C1INH) is known to exert its inhibitory effect by binding to several target proteases of the contact and complement systems. One of C1INH’s targets comprise mannose-binding lectin (MBL), a critical player in post-stroke pathophysiology. We therefore explored the effects of recombinant human (rh) and plasma derived (pd) C1INH in C57BL/6J mice subjected to transient occlusion of the middle cerebral artery (tMCAo), receiving 15 U/mouse of pd or rhC1INH intravenously, at reperfusion. We analyzed the compounds’ (i) neuroprotective effects, (ii) plasma presence, (iii) effects on circulating and brain MBL, (iv) time course of endothelial deposition, and (v) effects on the formation of active complement products. rhC1INH-treated mice had neuroprotective effects, including reduced behavioral deficits and neuronal loss, associated with decreased MBL brain deposition and decreased formation of complement C4b active fragments. In contrast, pdC1INH did not show these neuroprotective effects despite its longer plasma residence time. We also analyzed the response to tMCAo in C1INH-deficient mice, observing a poorer ischemic outcome compared to the wild type mice, which could be partially prevented by rhC1INH administration.In conclusion, we show that rhC1INH exhibits stronger neuroprotective effects than the corresponding plasma-derived protein after experimental ischemia/reperfusion injury in the brain, placing it as a promising drug for stroke. Differential effects are likely related to more effective MBL inhibition which further confirms it as a useful pharmacological target for stroke.     

Temporo-parietal theta activity correlates with misery perfusion in arterial occlusive disease

ObjectiveTemporo-parietal theta activity (TPTA), often detected in hemispheres with internal carotid (ICA) or middle cerebral artery (MCA) occlusive lesions, is more clearly separated from occipital alpha activity by magnetoencephalography (MEG) than electroencephalography. The present study investigated whether TPTA is correlated with misery perfusion, a surgically correctable type of hemodynamic impairment.MethodsAwake MEG was measured in 56 patients with ICA or MCA occlusive lesions. Regional cerebral blood flow (rCBF) and regional cerebrovascular reactivity (rCVR) to acetazolamide were measured in the MCA territory by xenon-133 single-photon emission computed tomography. MEG was repeated in 10 patients after vascular reconstruction surgery.ResultsFourteen patients showed TPTA in the lesion hemisphere (n = 13) or bilaterally (n = 1). The presence of TPTA was significantly correlated with both reduced rCBF and reduced rCVR (P = 0.0009). After surgery, TPTA disappeared in 7 of the 10 studied patients.ConclusionsThe presence of TPTA suggests misery perfusion, which is characterized by reduced rCBF and reduced rCVR.SignificanceMEG can detect the presence of reversible and surgically remediable cerebral ischemia before the development of complete infarction.     

Susceptibility to life-threatening ventricular arrhythmias in an animal model of paradoxical sleep deprivation

BackgroundAccording to some reports regarding the increase of cardiac events following sleep deprivation, our study was conducted to clarify the effects of rapid eye movement (REM) sleep deprivation on susceptibility to lethal ventricular arrhythmias in rat.MethodsThe animal groups included the control group; the sham 48 and sham 72 groups (without sleep deprivation); and the test 48 and test 72 groups, who experienced REM sleep deprivation for 48 h and 72 h, respectively. For induction of cardiac arrhythmia, aconitine was infused via the tail vein of the animals.ResultsAfter 72 h of REM sleep deprivation, the blood pressure (BP) levels and the QTc interval of the electrocardiogram (ECG) were significantly increased (P < .05 and P < .01, respectively). However, the sleep deprivation had no significant effect on the heart rate (HR), myocardial oxygen consumption index, and plasma corticosterone level. Furthermore, sleep deprivation increased the latency times of premature ventricular contraction (PVC), ventricular tachycardia (VT), and also the PVC number; however, it did not increase the number, duration, and severity of VT and ventricular fibrillation (VF).ConclusionOur findings suggest that 72 h of REM sleep deprivation is associated with increased risk for hypertension and QT interval prolongation under nonstressful conditions; however, it does not increase the susceptibility to lethal ventricular arrhythmia in rat.     

High frequency repetitive transcranial magnetic stimulation decreases cerebral vasomotor reactivity

ObjectiveRepetitive Transcranial Magnetic Stimulation (rTMS) has been recently employed as a therapeutic strategy for stroke, although its effects on cerebral hemodynamics has been poorly investigated. This study aims to examine the impact of high frequency rTMS on cerebral vasomotor reactivity (VMR).MethodsTwenty-nine healthy subjects were randomly assigned to real (19) or sham 17-Hz rTMS, applied on primary motor cortex (M1) of the dominant hemisphere. All subjects underwent Transcranial Doppler of the middle cerebral arteries to evaluate mean flow velocity and VMR before (T₀) and within 10 min (T₁) following rTMS. Four subjects underwent further VMR evaluations at 2 (T₂), 5 (T₃) and 24 h (T₄) after rTMS. As a control condition, 10 subjects underwent real (5) or sham rTMS on calcarine cortex. In addition, five acute stroke patients underwent five daily rTMS sessions on the affected hemisphere mimicking a therapeutic trial.ResultsFollowing real rTMS on M1 (p = 0.002) and calcarine cortex (p < 0.001) VMR decreased with respect to T₀ in both hemispheres, while no change was observed after sham rTMS (p > 0.6). VMR tended to remain lower than T₀ until T_3. Cerebral VMR decreased independently of the stimulated side also in the patients’ group.ConclusionsHigh frequency rTMS reduces cerebral VMR, possibly as a secondary effect on autonomic control of cerebral hemodynamics.SignificanceThe effect of rTMS on cerebral hemodynamics should be carefully considered before proceeding toward a therapeutic application in stroke patients.     

Effect of pretreatment with a tyrosine kinase inhibitor (PP1) on brain oedema and neurological function in an automated cortical cryoinjury model in mice

Cerebral oedema is a significant cause of morbidity in neurosurgical practice. To our knowledge, there is no ideal drug for prevention or treatment of brain oedema. Based on the current understanding of the pathogenesis of brain oedema, tyrosine kinase inhibitors could have a role in reducing brain oedema but preclinical studies are needed to assess their effectiveness. We evaluated the role of pretreatment with 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo(3,4-d)pyrimidine (PP1), an Src tyrosine kinase inhibitor, in reducing cerebral oedema and preserving neurological function measured 24 hours after an automated cortical cryoinjury in mice. Sixteen adult male Swiss albino mice were subjected to an automated cortical cryoinjury using a dry ice–acetone mixture. The experimental group (n = 8) received an intraperitoneal injection of PP1 dissolved in dimethyl sulfoxide (DMSO) at a dose of 1.5 mg/kg body weight 45 minutes prior to the injury. The control group (n = 8) received an intraperitoneal injection of DMSO alone. A further eight mice underwent sham injury. The animals were evaluated using the neurological severity score (NSS) at 24 hours post-injury, after which the animals were sacrificed and their brains removed, weighed, dehydrated for 48 hours and weighed again. The percentage of brain water content was calculated as: {[(wet weight – dry weight)/wet weight] × 100}. The mean (standard deviation, SD) NSS was 11.7 (1.8) in the experimental group and 10.5 (1.3) in the control group (p = 0.15). The mean (SD) percentage water content of the brain was 78.6% (1.3%) in the experimental group and 77.2% (1.1%) in the control group (p = 0.03). The percentage water content in the experimental and control groups were both significantly higher than in the sham injury group. The immediate pre-injury administration of PP1 neither reduced cerebral oedema (water content %) nor preserved neurological function (NSS) when compared to a control group in this model of cortical cryoinjury.     

Dynamic of neurochemical alterations in striatum,hippocampus and cortex after the 6-OHDA mesostriatal lesion

Immediate neurochemical alterations produced by 6-OHDA could explain the general toxic pattern in the central nervous system. However, no evidences describe the effects of 6-OHDA on early changes of neurotransmitters in rats’ striatum, cortex and hippocampus. In our study, unilateral 6-OHDA injection into medial forebrain bundle (MFB) was used in rats, then five neurotransmitters were analyzed at 3, 6, 12, 24, 48 and 72 h, respectively. Results showed that 6-OHDA injection caused a sharp decline of striatal dopamine (DA) levels in the first 12 h followed by a further reduction between 12 and 48 h. However, striatal levels of homovanillic acid (HVA) were stable in the first 12 h and showed a marked reduction between 12 and 24 h. Striatal levels of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) decreased linearly for 72 h, whereas levels of norepinephrine (NE) showed a slight reduction in the first 48 h, and returned back to normal afterwards. Striatal HVA/DA ratio increased significantly in the first 12 h, but 5-HIAA/5-HT ratio showed a sharp increase between 12 and 72 h. Besides, neurochemical alterations were also found in hippocampus and cortex, and the correlations of neurotransmitters were analyzed. Our study indicated that NE system had little influence in the early phase of 6-OHDA injection, moreover, early neurochemical alterations were involved with striatum, hippocampus and cortex.     

Lymphocyte infiltration of neocortex and hippocampus after a single brief seizure in mice

Various immune responses have been described in epileptic patients and animal models of epilepsy, but immune responses in brain after a single seizure are poorly understood. We studied immune responses in brain after a single brief generalized tonic–clonic seizure in mice. C57bl/6 mice, either unanesthetized or anesthetized (pentobarbital, ethyl chloride) received either electrical (15–30 mA, 100 Hz, 1 s) or sham stimulation (subcutaneous electrodes over frontal lobe, no current). Electrical stimulation of unanesthetized mice resulted in tonic–clonic convulsions with hind-limb extension (maximal seizure), tonic–clonic convulsions without hind-limb extension (submaximal seizure), or no seizure. In contrast, such stimulation of anesthetized mice did not result in seizure. Mice were killed at 1 h–7 days after seizure. Brains or regions dissected from brain (neocortex, hippocampus, midbrain, cerebellum) of each group were pooled, single cell suspensions prepared, and cells separated according to density. CD4⁺ (CD3⁺CD45^Hi) and CD8⁺ (CD3⁺CD45^Hi) T cell and CD45R⁺ (CD45^Hi) B cell numbers were determined by flow cytometry. At 24 h after a maximal seizure, CD4⁺ and CD8⁺ T cells and CD45R⁺ B cells appeared in brain, reaching peak numbers at 48 h, but were no longer detected at 7 days. CD4⁺ T cells and CD45R⁺ B cells were preferentially found in neocortex compared with hippocampus, whereas CD8⁺ T cells were preferentially found in hippocampus at 24 h after a maximal seizure. In contrast, virtually no lymphocytes were detected in brains of unstimulated or sham stimulated mice, unanesthetized stimulated mice after submaximal or no seizure, and anesthetized stimulated mice at 1 h–7 day. Neither Ly6-G+ neutrophils nor erythrocytes were detected in brains of any animals, nor was there any detectable increase of blood–brain barrier permeability by uptake of Evans Blue dye. The results indicate that lymphocyte entry into brain after a single brief seizure is due to a selective process of recruitment into cortical regions.     

EEG,evoked potentials and pulsed Doppler in asphyxiated term infants

ObjectiveTo evaluate electroencephalograms (EEG), evoked potentials (EPs) and Doppler findings in the cerebral arteries as predictors of a 1-year outcome in asphyxiated newborn infants.MethodsEEG and EPs (brain stem auditory (BAEP), somatosensory (SEP), visual (VEP) evoked potentials) were assessed in 30 asphyxiated and 30 healthy term infants during the first days (range 1–8). Cerebral blood flow velocities (CBFV) were measured from the cerebral arteries using pulsed Doppler at ∼24 h of age. EEG, EPs, Doppler findings, symptoms of hypoxic ischemic encephalopathy (HIE) and their combination were evaluated in predicting a 1-year outcome.ResultsAn abnormal EEG background predicted poor outcome in the asphyxia group with a sensitivity of 67% and 81% specificity, and an abnormal SEP with 75% and 79%, respectively. Combining increased systolic CBFV (mean + 3SD) with abnormal EEG or SEP improved the specificity, but not the sensitivity. The predictive values of abnormal BAEP and VEP were poor. Normal EEG and SEP predicted good outcome in the asphyxia group with sensitivities from 79% to 81%. The combination of normal EEG, normal SEP and systolic CBFV < 3SD predicted good outcome with a sensitivity of 74% and 100% specificity.ConclusionsCombining abnormal EEG or EPs findings with increased systolic CBFV did not improve prediction of a poor 1-year outcome of asphyxiated infants. Normal EEG and normal SEP combined with systolic CBFV < 3SD at about 24 h can be valuable in the prediction of normal 1-year outcome.SignificanceCombining systolic CBFV at 24 h with EEG and SEP examinations can be of use in the prediction of normal 1-year outcome among asphyxiated infants.     

JNK inhibition and inflammation after cerebral ischemia

The c-Jun-N-terminal kinase signaling pathway (JNK) is highly activated during ischemia and plays an important role in apoptosis and inflammation. We have previously demonstrated that D-JNKI1, a specific JNK inhibitor, is strongly neuroprotective in animal models of stroke. We presently evaluated if D-JNKI1 modulates post-ischemic inflammation such as the activation and accumulation of microglial cells.Outbred CD1 mice were subjected to 45 min middle cerebral artery occlusion (MCAo). D-JNKI1 (0.1 mg/kg) or vehicle (saline) was administered intravenously 3 h after MCAo onset. Lesion size at 48 h was significantly reduced, from 28.2 ± 8.5 mm³ (n = 7) to 13.9 ± 6.2 mm³ in the treated group (n = 6). Activation of the JNK pathway (phosphorylation of c-Jun) was observed in neurons as well as in Isolectin B4 positive microglia. We quantified activated microglia (CD11b) by measuring the average intensity of CD11b labelling (infra-red emission) within the ischemic tissue. No significant difference was found between groups. Cerebral ischemia was modelled in vitro by subjecting rat organotypic hippocampal slice cultures to oxygen (5%) and glucose deprivation for 30 min. In vitro, D-JNKI1 was found predominantly in NeuN positive neurons of the CA1 region and in few Isolectin B4 positive microglia. Furthermore, 48 h after OGD, microglia were activated whereas resting microglia were found in controls and in D-JNKI1-treated slices.Our study shows that D-JNKI1 reduces the infarct volume 48 h after transient MCAo and does not act on the activation and accumulation of microglia at this time point. In contrast, in vitro data show an indirect effect of D-JNKI1 on the modulation of microglial activation.     

Flow diversion within seven days after stroke onset is associated with favorable outcome in anterior circulation stroke

Anterior cerebral artery (ACA) flow diversion (FD), defined as ipsilateral mean velocity (MV) of at least 30% greater than the contralateral artery, could be seen an indirect sign of leptomeningeal collateralization in the setting of middle cerebral artery occlusion. The purpose of the study was to evaluate the association between dynamic FD and functional outcome in acute anterior stroke patients with large artery occlusion. Acute middle cerebral artery (MCA) or internal carotid artery (ICA) occlusive stroke patients within 12 h were recruited. Transcranial Doppler ultrasound was done at baseline, 24 h and 7 d after onset and velocities of MCA and ACA were recorded. FD ratio was calculated by dividing the ipsilateral ACA MV by the contralateral ACA MV. FD was determined positive when FD ratio ≥1.3. Outcome was assessed by 90-day modified Rankin’s Scale (mRS). The association between FD at different time points and functional outcome were analyzed. 16 patients (median age of 67 and 75% were male) were recruited. FD ratio showed a trend of decline but did not reach statistical significance (p = 0.056). The proportion of FD at baseline (p = 0.026), 24 h (p = 0.001) and 7d (p = 0.044) was significantly higher in patients with favorable outcome. Higher FD ratio at baseline (p = 0.02) and 24 h (p = 0.003) were significantly associated with favorable outcome. These results suggested that FD ratio showed a trend of decline after stroke onset. Presence of FD within 7 days was associated with favorable functional outcome in acute MCA/ICA occlusive stroke patients.     

A rabbit model of aneurysmal subarachnoid hemorrhage by ear central artery-suprasellar cistern shunt

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening hemorrhagic cerebrovascular disease. The concept of early brain injury (EBI), induced by sharply increased intracranial pressure (ICP) and low cerebral perfusion pressure (CPP) with cerebral global ischemia following aneurysm rupture, has been increasingly accepted. However, EBI has not been well studied partly due to lack of an ideal animal model. The purpose of this study was to establish a new aSAH model which can mimic the pathophysiological damage of EBI. Right frontal craniotomy was performed on New Zealand rabbits for placing a PE-50 tube at the suprasella cistern and an ICP probe at the anterior cranial fossa. The central ear artery was punctured and blood was shunted into the suprasellar cistern through the PE-50 tube. ICP, blood pressure, CPP and heart rate peri-aSAH were monitored throughout the experiments. The rabbits were examined for neurological deficits at 24 h post-SAH. Brain coronal sections near the optic chiasma were assessed by HE and Cresyl violet staining. Three minutes after SAH induction, the ICP peaked to 61.7 ± 9.8 mmHg while CPP decreased to nadir 23.5 ± 8.9 mmHg, and both were gradually restored in 15 min. At 24 h post-SAH, significant neurological deficits were found in SAH rabbits as compared to the sham-operated animals. In addition, neuronal degeneration and loss were also detected. Our results indicate that a new rabbit model of aSAH with EBI is successfully established. Moreover, this model is controllable, economical, and no side-injury to the main artery.     

Neuronal protective effects of focal ischemic pre- and/or postconditioning on the model of transient focal cerebral ischemia in rats

We investigated the neuroprotective effects of pre- and postconditioning on infarct volume in the transient middle cerebral artery occlusion (MCAo) model in rats. Thirty-two male rats were divided into occlusion, preconditioning, postconditioning and both pre- and postconditioning groups. MCAo (120 minutes) was monitored with continuous cerebral tissue oxygen (O₂) pressure (PtiO₂). Pre-conditioning comprised 10 minutes of MCAo, 24 hours prior to the 120 minute MCAo. The postconditioning algorithm was 30 seconds of reperfusion followed by 30 seconds of MCAo. This cycle was repeated 3 times at the onset of reperfusion. Comparison of infarct volumes showed a significant difference between the conditioned groups and occlusion group. Although there was better protection in the preconditioning group compared with the other two conditioned groups, the results did not reach statistically significant levels. The results suggest that preconditioning, postconditioning and pre/post conditioning have protective effects on cerebral ischemia.