Cerebral Cortical Ischemia Research Articles

Neuroprotective Effects of Melittin Against Cerebral Ischemia and Inflammatory Injury via Upregulation of MCPIP1 to Suppress NF-κB Activation In Vivo and In Vitro

Melittin, a principal constituent of honeybee venom, exhibits diverse biological effects, encompassing anti-inflammatory capabilities and neuroprotective actions against an array of neurological diseases. In this study, we probed the prospective protective influence of melittin on cerebral ischemia, focusing on its anti-inflammatory activity. Mechanistically, we explored whether monocyte chemotactic protein-induced protein 1 (MCPIP1, also known as ZC3H12A), a recently identified zinc-finger protein, played a role in melittin-mediated anti-inflammation and neuroprotection. Male C57/BL6 mice were subjected to distal middle cerebral artery occlusion to create a focal cerebral cortical ischemia model, with melittin administered intraperitoneally. We evaluated motor functions, brain infarct volume, cerebral blood flow, and inflammatory marker levels within brain tissue, employing quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assays, and western blotting. In vitro, an immortalized BV-2 microglia culture was stimulated with lipopolysaccharide (LPS) to establish an inflammatory cell model. Post-melittin exposure, cell viability, and cytokine expression were examined. MCPIP1 was silenced using siRNA in LPS-induced BV-2 cells, with the ensuing nuclear translocation of nuclear factor-κB assessed through cellular immunofluorescence. In vivo, melittin enhanced motor functions, diminished infarction, fostered blood flow restoration in ischemic brain regions, and markedly inhibited the expression of inflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor-α, and nuclear factor-κB). In vitro, melittin augmented MCPIP1 expression in LPS-induced BV-2 cells and ameliorated inflammation-induced cell death. The neuroprotective effect conferred by melittin was attenuated upon MCPIP1 knockdown. Our findings establish that melittin-induced tolerance to ischemic injury is intrinsically linked with its anti-inflammatory capacity. Moreover, MCPIP1 is, at the very least, partially implicated in this process.

Liraglutide Ameliorates Cerebral Ischemia in Mice via Antipyroptotic Pathways.

It was recently shown that pyroptosis, an inflammatory form of programmed cell death, is critically involved in the pathogenesis of ischemic stroke. Liraglutide (Lg) is a novel long-acting analog of glucagon-like peptide-1 that has potential protective effects against stroke. However, the relationship between Lg and pyroptosis in the brain is not well defined. In this study, we found that injection of Lg significantly improved the recovery of motor function, increased cerebral blood flow and ameliorated cerebral damage in a mouse model of focal cerebral cortical ischemia. Our results revealed that Lg treatment significantly reduced the levels of NLRP3, Caspase1, IL-1β and the pore-forming protein gasdermin D in microglial cells in vitro, suggesting that the neuroprotective effect of Lg may be achieved through the inhibition of pyroptosis. Furthermore, by using a specific inhibitor of NOD-like receptor protein 3 (NLRP3), we confirmed that the antipyroptotic mechanism of Lg may be mediated by NLRP3 in vivo. Our present study unveils a novel neuroprotective mechanism through which Lg alleviates ischemia by exerting NLRP3-dependent antipyroptotic effects.

A novel method for quantitative evaluation of motor evoked potential monitoring during cerebrovascular surgeries

Transcranial motor evoked potential (MEP) monitoring, intended to assess cerebral cortical ischemia, may produce false negative results when the stimulation inadvertently activates the deep, subcortical motor pathways. This study examined hand MEP onset latency as a potential means to differentiate superficial versus deep stimulus penetration in surgical patients monitored for cerebral ischemia.Intraoperative MEP data were prospectively collected from 40 patients treated for intracranial aneurysm or carotid stenosis. Onset latencies of hand MEP responses were measured over a range of stimulation intensities from both the contralateral and ipsilateral hand (crossover responses). At the threshold for superficial, cortical stimulation of the contralateral hand, the MEP latency was 26.9 ± 0.4 ms. MEP onset latencies measurements became shorter as stimulation intensities were increased. At the maximum intensity (when crossover response was usually generated), the contralateral hand MEP latency of 22.5 ± 0.3 ms was significantly shorter than at threshold stimulation (p < 0.001). Latency-stimulus intensity plots best fit a 3 parameter hyperbolic decay function (r2 = 0.85 ± 0.02) and revealed a narrow window of acceptable MEP stimuli to obtain superficial cortical activation. Our analysis refutes the utility of the crossover response in reliably gauging depth of activation. Additionally, we found that differentiation between long and short MEP onset latency times may serve as a dependable marker for depth of stimulation. Attention to hand MEP onset latency may reduce inadvertent stimulation of the deep corticospinal tract pathways and avoid false negative MEP recordings during cerebrovascular surgeries.

Brain-derived CCR5 Contributes to Neuroprotection and Brain Repair after Experimental Stroke.

Chemokine (C-C motif) receptor 5 (CCR5) is expressed not only in the immune cells but also in cerebral cells such as neurons, glia, and vascular cells. Stroke triggers high expression of CCR5 in the brain. However, the role of CCR5 in stroke remains unclear. In this study, using bone marrow chimeras we have determined the involvement of brain-derived or bone marrow-derived CCR5 in neuroprotection and brain repair after experimental stroke. CCR5-/- mice that received either wild-type (WT) or CCR5-/- bone marrow transplantation showed larger infarction sizes than the WT mice that received either WT or CCR5-/- bone marrow transplantation in both the acute (48h) and subacute (2 months) phases after cerebral cortical ischemia, suggesting that the lack of CCR5 in the brain leads to severe brain damage after stroke. However, the lack of CCR5 in the bone marrow-derived cells did not affect infarction size. The impairments of somatosensory-motor function and motor coordination were exacerbated in the mice lacking CCR5 in the brain. At 2 months post-stroke, increased degenerative neurons, decreased dendrites and synapses, decreased Iba1+ microglia/ macrophages, reduced myelination and CNPase+ oligodendrocytes in the peri-infarct cortex were observed in the mice lacking CCR5 in the brain. These pathological changes are significantly correlated with the increased infarction size and exacerbated neurological deficits. These data suggest that brain-derived CCR5 plays a key role in neuroprotection and brain repair in the subacute phase of stroke. This study reveals a novel role of CCR5 in stroke, which sheds new light on post-stroke pathomechanism.

Delayed Administration of the Glucagon-Like Peptide 1 Analog Liraglutide Promoting Angiogenesis after Focal Cerebral Ischemia in Mice

Glucagon-like peptide 1 (GLP-1) analogs administered before or after cerebral ischemia have been shown to provide neuroprotection. Here, we explored whether delayed administration of a GLP-1 analog, liraglutide, could improve long-term functional recovery and promote angiogenesis after stroke. In the present study, mice were established as a focal cerebral cortical ischemia model and were intraperitoneally administered liraglutide or normal saline (NS) daily for 14 consecutive days, starting 1 day after cerebral ischemia. The neurological deficits were evaluated using rotarod test. The microvessel density (MVD) and endothelial cell (EC) proliferation were assessed by immunohistochemical staining. The expression of vascular endothelial growth factor (VEGF) was assessed by Western blot analysis. Liraglutide significantly reduced infarct volume and improved the rotarod test scores, compared with mice treated with NS. Liraglutide also greatly increased the MVD and EC proliferation and simultaneously upregulated the expression of VEGF in the cerebral ischemic area. These results demonstrated that liraglutide promoted angiogenesis and long-term recovery of cerebral ischemia through increasing the expression of VEGF.

Crossed Cerebellar Atrophy of the Lateral Cerebellar Nucleus in an Endothelin-1-Induced, Rodent Model of Ischemic Stroke.

Crossed cerebellar diaschisis (CCD) is a functional deficit of the cerebellar hemisphere resulting from loss of afferent input consequent to a lesion of the contralateral cerebral hemisphere. It is manifested as a reduction of metabolism and blood flow and, depending on severity and duration, it can result in atrophy, a phenomenon known as crossed cerebellar atrophy (CCA). While CCA has been well-demonstrated in humans, it remains poorly characterized in animal models of stroke. In this study we evaluated the effects of cerebral cortical ischemia on contralateral cerebellar anatomy using an established rodent model of chronic stroke. The effects of cortical ischemia on the cerebellar hemispheres, vermis and deep nuclei were characterized. Intracortical microinjections of endothelin-1 (ET-1) were delivered to the motor cortex of Long Evans rats to induce ischemic stroke, with animals sacrificed 6 weeks later. Naive animals served as controls. Cerebral sections and cerebellar sections including the deep nuclei were prepared for analysis with Nissl staining. Cortical ischemia was associated with significant thickness reduction of the molecular layer at the Crus 1 and parafloccular lobule (PFL), but not in fourth cerebellar lobule (4Cb), as compared to the ipsilesional cerebellar hemisphere. A significant reduction in volume and cell density of the lateral cerebellar nucleus (LCN), the rodent correlate of the dentate nucleus, was also noted. The results highlight the relevance of corticopontocerebellar (CPC) projections for cerebellar metabolism and function, including its direct projections to the LCN.

Computed tomography perfusion as a diagnostic tool for seizures after ischemic stroke.

Cerebral cortical ischemia is a risk factor for post-stroke seizures. However, the optimal imaging method is unclear. We investigated CT perfusion (CTP) in detecting cortical ischemia and its correlation with post-stroke seizures compared with non-contrast CT (NCCT). We included patients with acute ischemic stroke admitted to the Royal Melbourne Hospital between 2009 and 2014. Post-stroke seizure information was collected. Cortical involvement was determined on acute NCCT and CTP (T max, cerebral blood volume [CBV], and cerebral blood flow [CBF]). The association between cortical involvement detected by different imaging modalities and post-stroke seizures was examined. Three-hundred fifty-two patients were included for analysis. Fifty-nine percent were male, and median age was 73years (inter-quartile range 61-82). Follow-up was available for 96%; median follow-up duration was 377days (inter-quartile range 91-1018days). Thirteen patients had post-stroke seizures (3.9%). Cortical involvement was significantly associated with post-stroke seizures across all modalities. CBV had the highest hazard ratio (11.3, 95% confidence interval (CI) 1.1-41.2), followed by NCCT (5.3, 95% CI 1.5-18.0) and CBF (4.2, 95% CI 1.1-15.2). Sensitivity was highest for T max (100%), followed by CBV and CBF (both 76.9%) and NCCT (63.6%). Specificity was highest for CBV (77.8%), then NCCT (75.6%), CBF (54.0%), and T max (29.1%). Receiver-operating characteristic area under the curve was significantly different between imaging modalities (p < 0.001), CBV 0.77, NCCT 0.70, CBF 0.65, and T max 0.65. CTP may improve sensitivity and specificity of cortical involvement for post-stroke seizures compared to NCCT.

Mannitol infusion immediately after reperfusion suppresses the development of focal cortical infarction after temporary cerebral ischemia in gerbils

Previously we found that, after temporary cerebral ischemia, microvasculogenic secondary focal cerebral cortical ischemia occurred, caused by microvascular obstruction due to compression by swollen astrocytic end-feet, resulting in focal infarction. Herein, we examined whether mannitol infusion immediately after restoration of blood flow could protect the cerebral cortex against the development of such an infarction. If so, the infusion of mannitol might improve the results of vascular reperfusion therapy. We selected stroke-positive animals during the first 10 min after left carotid occlusion performed twice with a 5-h interval, and allocated them into four groups: sham-operated control, no-treatment, mannitol-infusion, and saline-infusion groups. Light- and electron-microscopic studies were performed on cerebral cortices of coronal sections prepared at the chiasmatic level, where the focal infarction develops abruptly in the area where disseminated selective neuronal necrosis is maturing. Measurements were performed to determine the following: (A) infarct size in HE-stained specimens from all groups at 72 and 120 h after return of blood flow; (B) number of carbon-black-suspension-perfused microvessels in the control and at 0.5, 3, 5, 8, 12 and 24 h in the no-treatment and mannitol-infusion groups; (C) area of astrocytic end-feet; and (D) number of mitochondria in the astrocytic end-feet in electron microscopic pictures taken at 5 h. The average decimal fraction area ratio of infarct size in the mannitol group was significantly reduced at 72 and 120 h, associated with an increased decimal fraction number ratio of carbon-black-suspension-perfused microvessels at 3, 5 and 8 h, and a marked reduction in the size of the end-feet at 5 h. Mannitol infusion performed immediately after restitution of blood flow following temporary cerebral ischemia remarkably reduced the size of the cerebral cortical focal infarction by decreasing the swelling of the end-feet, thus preventing the microvascular compression and stasis and thereby microvasculogenic secondary focal cerebral ischemia.

Influence of constraint‐induced movement therapy upon evoked potentials in rats with cerebral infarction

Constraint-induced movement therapy (CIMT) is an effective treatment promoting motor recovery of upper extremity function in stroke patients. The objective of the present study was to determine the effect of CIMT on the evoked potentials in rats with focal cerebral cortical ischemia induced by endothelin-1 (ET-1). Thirty rats were randomly assigned to the sham, infarct or CIMT groups. ET-1 was injected stereotaxically into the forelimb area of the cerebral cortex in the dominant hemisphere. Custom-made constraint jackets were applied to limit movement of the unaffected forelimb in the CIMT group. Motor and sensory function of the forelimb was evaluated by a pellet retrieval task and forearm asymmetry test. Electrophysiologic changes were evaluated by motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SEPs). The location and extent of cerebral ischemia were confirmed and compared histologically. The CIMT group showed better recovery in the pellet retrieval task. Forelimb use was more symmetrical in the CIMT group. The waveform of the SEP was reversed and delayed in the infarct group, but it was preserved in the CIMT group with amplitude decrease only. The estimated volume of infarction was smaller in the CIMT group, although statistically not significant. The results demonstrate that CIMT can promote recovery of motor function in focal cerebral cortical infarcts, and that recovery may be related to reorganization of the cerebral neuronal network in the somatosensory pathway.

Brain self-protection: The role of endogenous neural progenitor cells in adult brain after cerebral cortical ischemia

Convincing evidence has shown that brain ischemia causes the proliferation of neural stem cells/neural progenitor cells (NSCs/NPCs) in both the subventricular zone (SVZ) and the subgranular zone (SGZ) of adult brain. The role of brain ischemia-induced NSC/NPC proliferation, however, has remained unclear. Here we have determined whether brain ischemia-induced amplification of the NSCs/NPCs in adult brain is required for brain self-protection. The approach of intracerebroventricular (ICV) infusion of cytosine arabinoside (Ara-C), an inhibitor for cell proliferation, for the first 7 days after brain ischemia was used to block ischemia-induced NSC/NPC proliferation. We observed that ICV infusion of Ara-C caused a complete blockade of NSC/NPC proliferation in the SVZ and a dramatic reduction of NSC/NPC proliferation in the SGZ. Additionally, as a result of the inhibition of ischemia-induced NSC/NPC pool amplification, the number of neurons in the hippocampal CA1 and CA3 was significantly reduced, the infarction size was significantly enlarged, and neurological deficits were significantly worsened after focal brain ischemia. We also found that an NSC/NPC-conditioned medium showed neuroprotective effects in vitro and that adult NSC/NPC-released brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) are required for NSC/NPC-conditioned medium-induced neuroprotection. These data suggest that NSC/NPC-generated trophic factors are neuroprotective and that brain ischemia-triggered NSC/NPC proliferation is crucial for brain protection. This study provides insights into the contribution of endogenous NSCs/NPCs to brain self-protection in adult brain after ischemia injury.

A combined treatment with 1α,25-dihydroxy-vitamin D 3 and 17β-estradiol reduces the expression of heat shock protein-32 (HSP-32) following cerebral cortical ischemia

1α,25-(OH) 2-vitamin D 3 (1,25-D 3) and 17β-estradiol are both known to act neuroprotectively in certain experimental in vitro and in vivo settings and it has been noted that both steroids lead to an upregulation of certain neurotrophic factors. Here, we studied the effects of 1α,25-(OH) 2-vitamin D 3 or 17β-estradiol or their combined application on heat shock protein-32 (HSP-32) distribution after focal cortical ischemia using the well established photothrombosis model. Heat shock protein-32 is a well-established marker of the cerebral oxidative stress response and contributes to neuroprotection by metabolising cytotoxic free heme to carbon monoxide, iron and biliverdin. Photothrombotically lesioned rats were injected i.p. 1 h after injury with either 1 μg 1α,25-(OH) 2-vitamin D 3/kg or 7 μg 17β-estradiol/kg or a combination of both steroids. Groups of non-lesioned steroid-treated rats and lesioned, solvent-treated rats served as controls. In contrast to non-lesioned rats, in lesioned animals a significant increase in heat shock protein-32 expression occurred which was slightly, but non-significantly altered in the groups treated either with 1α,25-(OH) 2-vitamin D 3 or 17β-estradiol alone when compared to the solvent-treated control group. Only the combined treatment with 1α,25-(OH) 2-vitamin D 3 and 17β-estradiol resulted in a significant reduction of glial heat shock protein-32 immunoreactivity within the lesion-remote cortical areas supplied by the affected middle cerebral artery (MCA), indicating that both steroids act synergistically in a protective manner.

Cerebral cortical oxygenation changes during OPCAB surgery

Background We investigated the changes occurring in cerebral cortical oxygenation during off-pump coronary artery bypass (OPCAB) surgery using near infrared spectroscopy (NIRS). Methods Measurement of cerebral cortical oxygenation changes included concentration of deoxygenated hemoglobin [HHb], oxygenated hemoglobin [O 2Hb], changes in the redox status of the cytochrome c oxidase [Cyt-Ox], cerebral saturation as expressed by the tissue oxygenation index (TOI), and cerebral blood volume (CBV) as expressed by tissue hemoglobin index (THI). Measurements were performed in 23 consecutive patients during grafting of: left anterior descending (LAD setup 1; n = 23), posterior descending (PDA setup 2; n = 17), and Circumflex (Cx setup 3; n = 19) coronary arteries. Measurements were performed before any surgical manipulation (baseline), following positioning of the pressure stabilizer during construction of the distal anastomosis and 2 minutes after the completion of each distal anastomosis with the heart returned to its natural position. Results There were no in-hospital deaths, neurologic deficits, or myocardial infarcts. Compared to baseline, during LAD grafting there was a marked reduction in [O 2Hb] [−1.08 (−1.77 to −0.39), mean difference (95% CI) ( p < 0.0008)], without a significant change in [HHb]. There was also a 4% reduction in cerebral saturation and a 3% fall in CBV (both p < 0.05). Setup 2 (PDA) was associated with a marked decrease of [O 2Hb] [−1.92 (−2.95 to −0.88) mean difference (95% CI) ( p < 0.0025)], which was accompanied by an increase in [HHb] [1.89 (1.00 to 2.77) mean difference (95% CI) ( p < 0.0025)], and a 4% reduction in cerebral saturation ( p < 0.0008). Grafting of the Cx was associated with a marked increase in [HHb] [2.85 (1.46 to 4.2) mean difference (95% CI) ( p < 0.0025)], with no changes in [O 2Hb], a 6% reduction in cerebral saturation, and a 12% increase in CBV (both p < 0.05). In all 3 settings, however, the changes were not associated with a modification in the redox state of [Cyt-Ox]. On returning to baseline condition, the changes in [O 2Hb] and TOI observed in setup 1 persisted, and a significant reduction was observed in the redox state of the [Cyt-Ox] when compared with baseline [−0.08 (−0.14 to −0.02) mean difference (95% CI) ( p < 0.002)]. For setups 2 and 3 there was recovery of the cerebral cortical oxygenation. Conclusions Grafting of the LAD on the beating heart is responsible for changes in cerebral cortical oxygenation which persist early after returning the heart to its natural position. Grafting of the Cx and PDA result in transient reversible changes. Trendelenburg positioning and right lateral tilting of the operating table during grafting of lateral and posterior walls might have a protective role in preventing cerebral cortical ischemia. Further studies are needed to assess the clinical importance of these observations.

Physostigmine induced reversal of ischemia following acute middle cerebral artery occlusion in the rat.

Cerebral cortical ischemia was induced in anesthetized rats by occlusion of the middle cerebral artery (MCA). Cerebral blood flow (CBF) was measured with the H2 clearance technique in the center and periphery of the ischemic territory. A decrease of CBF to about 50% of pre-occlusion values was observed in both areas. Administration of Physostigmine, a cholinesterase inhibitor, at a dose of 0.15 mg/Kg by intravenous route, induced an increase of CBF in the ischemic cortex. This change in CBF reached 120% of pre-occlusion level in the periphery and 80% of pre-occlusion value in the center of the area of distribution of the occluded artery. Although Physostigmine induced an increase in arterial blood pressure, the cerebral hyperemia observed both in normal and ischemic cortex could still be demonstrated after blockade of the pressor effect by bleeding or Phentolamine administration.

Computed tomography in global cerebral cortical ischemia of the neonate and young infant

The authors have encountered three unique neonates with global cerebral cortical ischemia. The pathogenesis and computed tomography scans of these patients who sustained profound hypoxemia is described. Follow-up computed tomography scans in each case demonstrated generalized loss of cortical substance.