Brain Ischemia-reperfusion Injury Research Articles

Neuroprotective effect of grape seed extract on brain ischemia: a proteomic approach.

Stroke is one of the leading causes of long-lasting disability in human and oxidative stress an important underlying cause. Molecular insights into pathophysiology of ischemic stroke are still obscure, and the present study investigated the protective effect of high dosage Grape Seed Extract (GSE 2.5g/kg) on brain ischemia-reperfusion (I/R) injury using a proteomic approach. Ischemia was realized by occlusion of the common carotid arteries for 30min followed by 1h reperfusion on control or GSE pre-treated rats, and a label-free quantification followed by mass spectrometry analysis used to evaluate I/R induced alterations in protein abundance and metabolic pathways as well as the protection afforded by GSE. I/R-induced whole brain ionogram dyshomeostasis, ultrastructural alterations, as well as inflammation into hippocampal dentate gyrus area, which were evaluated using ICP-OES, transmission electron microscopy and immuno-histochemistry respectively. I/R altered the whole brain proteome abundance among which 108 proteins were significantly modified (35 up and 73 down-regulated proteins). Eighty-four proteins were protected upon GSE treatment among which 27 were up and 57 down-regulated proteins, suggesting a potent protective effect of GSE close to 78%of the disturbed proteome. Furthermore, GSE efficiently prevented the brain from I/R-induced ion dyshomeostasis, ultrastructural alterations, inflammatory biomarkers as CD56 or CD68 and calcium burst within the hippocampus. To conclude, a potent protective effect of GSE on brain ischemia is evidenced and clinical trials using high dosage GSE should be envisaged on people at high risk for stroke.

Methanolic leaf extract of Punica granatum attenuates ischemia-reperfusion brain injury in Wistar rats: Potential antioxidant and anti-inflammatory mechanisms.

Objective(s):This study was conducted to evaluate the cerebroprotective effect of methanolic leaf extract of Punica granatum (MePG) in Wistar rats.Materials and Methods:The MePG was initially assessed for in vitro antioxidant activity, and later evaluated on LPS-induced RAW 264.7 cell line assay. Finally, the MePG was evaluated against ischemia-reperfusion (I/R) induced brain injury in Wistar rats.Results:In DPPH, FRAP and ORAC assays, the MePG has exhibited potent antioxidant activity. Further, the MePG has significantly inhibited the generation of nitrite, ROS and TNF-α in LPS-induced RAW 264.7 cell lines. Besides, global ischemia followed by reperfusion caused significant changes in the neurological and behavioral functions in I/R control animals compared to sham control. Additionally, in the I/R control group there was a substantial decrease in the catalase and superoxide dismutase activities; Likewise, reduced glutathione levels reduced and lipid peroxidation levels enhanced significantly. Also, pro-inflammatory cytokines such as TNF-α, IL-6, and ICAM-I were increased and the levels of IL-10 was decreased significantly. Furthermore, the I/R insult caused increase in brain volume and cerebral infarct formation. Similarly, histopathology of the brain tissue revealed hallmarks like necrosis, leukocyte infiltration, cerebral edema and vascular congestion in I/R control. Notably, MePG (200 and 400 mg/kg) pretreatment for 7 days, has attenuated all the I/R-persuaded pathological changes compared to I/R control. In addition, the LC-MS/MS analysis showed presence of acteoside, apigenin, gallic acid, gossypin, pentagalloyl glucose, quercetin, and rutin as major ingredients in the MePG.Conclusion:These findings suggest that the MePG possesses significant cerebroprotective activity.

Inhibition of GSK-3β alleviates cerebral ischemia/reperfusion injury in rats by suppressing NLRP3 inflammasome activation through autophagy

The nod-like receptor protein 3 (NLRP3) inflammasome has a critical role in cerebral ischemic injury, and autophagy is related to activation of the inflammasome under oxidative stress conditions. However, it is unclear how NLRP3 inflammasome activation is regulated. Glycogen synthase kinase 3β (GSK-3β) emerged as an important risk factor for brain ischemia reperfusion injury, and GSK-3β inhibits autophagic activity in many diseases. In this study, we examined whether NLRP3 inflammasome-derived inflammation could be ameliorated by GSK-3β inhibition in a cerebral ischemia reperfusion injury model and assessed whether autophagy is involved in this process. To establish ischemic reperfusion injury, we used a middle cerebral artery occlusion-reperfusion (MCAO/R) model in rats. A chemical inhibitor (SB216763) and GSK-3β siRNA were used to suppress GSK-3β activation and GSK-3β expression in vivo. The results demonstrated that SB216763 and GSK-3β siRNA improved neurological scores, reduced cerebral infarct volume, and decreased the levels of NLRP3 inflammasome, cleaved-caspase-1, IL-1β, and IL-18. Inhibiting GSK-3β activation enhanced autophagic activity (ratio of LC3B-II/LC3B-I and p62/SQSTM1), whereas treating with an autophagy inhibitor (3-MA) abrogated the inhibitory effect on NLRP3 inflammasome activation after GSK-3β inhibition. These results suggest that inhibiting GSK-3β downregulates NLRP3 inflammasome expression by increasing autophagic activity in cerebral ischemia reperfusion injury. GSK-3β might be an attractive specific target and that it functions by regulating the NLRP3 inflammasome.

Gasdermin D serves as a key executioner of pyroptosis in experimental cerebral ischemia and reperfusion model both in vivo and in vitro.

Even though ischemic stroke is among the leading causes of death worldwide, the pathogenic mechanisms underlying ischemia reperfusion (I/R) brain injury remain unclear. Gasdermin D (GSDMD), as an important factor of pyroptotic death execution downstream of caspase-11 (noncanonical inflammasome) and caspase-1 (canonical inflammasome), may be implicated in I/R injury. The current study aimed to investigate the role and possible underlying mechanisms of GSDMD in pyroptosis during I/R injury. Results indicated that the nucleotide-binding oligomerization domain-like receptors (NLR family) pyrin domain containing 3 (NLRP3) inflammasomes were assembled and activated after middle cerebral artery occlusion/reperfusion (MCAO/R), leading to increased levels of IL-1β and IL-18. Additionally, GSDMD levels were elevated, and its N-terminal fragment (GSDMD-N) was cleaved to induce pyroptosis after MCAO/R, which was partly dependent on caspase-1 activation and its Asp280 amino acid site. Furthermore, it was found that GSDMD-N could bind to membrane lipids and exhibit membrane-disrupting cytotoxicity, depending on its Glu15 and Leu156 amino acid sites. Nevertheless, the C-terminal fragment of gasdermin (GSDMD-C) exhibited an auto-inhibitory effect on GSDMD-N-induced pyroptosis via binding to GSDMD in the cytoplasm. Taken together, this information suggests that GSDMD may participate in caspase-1-mediated pyroptosis during I/R injury both in vivo and in vitro, which could be a potential therapeutic target to reduce brain I/R injury.

Synthesis, characterization and in vivo evaluation of honokiol bisphosphate prodrugs protects against rats’ brain ischemia-reperfusion injury

Honokiol (HK) usage is greatly restricted by its poor aqueous solubility and limited oral bioavailability. We synthesized and characterized a novel phosphate prodrug of honokiol (HKP) for in vitro and in vivo use. HKP greatly enhanced the aqueous solubility of HK (127.54 ± 15.53 mg/ml) and the stability in buffer solution was sufficient for intravenous administration. The enzymatic hydrolysis of HKP to HK was extremely rapid in vitro (T1/2 = 8.9 ± 2.11 s). Pharmacokinetics studies demonstrated that after intravenous administration of HKP (32 mg/kg), HKP was converted rapidly to HK with a time to reach the maximum plasma concentration of ∼5 min. The prodrug HKP achieved an improved T1/2 (7.97 ± 1.30 h) and terminal volume of distribution (26.02 ± 6.04 ml/kg) compared with direct injection of the equimolar parent drug (0.66 ± 0.01 h) and (2.90 ± 0.342 ml/kg), respectively. Furthermore, oral administration of HKP showed rapid and improved absorption compared with the parent drug. HKP was confirmed to maintain the bioactivity of the parent drug for ameliorating ischemia-reperfusion injury by decreasing brain infarction and improving neurologic function. Taken together, HKP is a potentially useful aqueous-soluble prodrug with improved pharmacokinetic properties which may merit further development as a potential drug candidate.

Mst1: Function and Mechanism in Brain and Myocardial Ischemia Reperfusion Injury.

Mammalian STE20-like kinase-1 (Mst1) is a generally expressed apoptosis-promoting kinase and a key bridge-builder of apoptotic signaling in the etiology of tissue injury. Despite the fact that the biological function of Mst1 and its role in the cell's signalling network have yet to be determined, however, there is a lot of evidence that Mst1 plays an important role in cell death which results from tissue injury. Previous studies have shown that Mst1 is not only a target for some apop-tosis-related molecules such as caspase 3 and P53, but also act as an activator of these proteinases to magnify apoptosis sig-nal pathways. This article reviews the role of Mst1 in the signaling pathways which is related with the neuronal cell apopto-sis or microglia activation following myocardial and brain injury. Therefore, this work contributes to better understanding of the pathological process of myocardial and brain injury

Tangeretin protects human brain microvascular endothelial cells against oxygen-glucose deprivation-induced injury.

Tangeretin, a citrus flavonoid extracted from the peel of citrus fruits, was reported to possess antiasthmatic, antioxidant, anti-inflammatory, and neuroprotective properties. However, the effect of tangeretin on human brain microvascular endothelial cells (HBMECs) has not been examined. This study was designed to investigate the protective effects of tangeretin on oxygen-glucose deprivation (OGD)-induced injury of HBMECs, and explore the underlying mechanisms. Our results showed that tangeretin improved HBMECs viability in response to OGD. In addition, tangeretin was able to increase the activity of superoxide dismutase and decrease the levels of reactive oxygen speciesand malondialdehyde (MDA), as well as ameliorate cell apoptosis in OGD-stimulated HBMECs. Mechanistic studies showed that tangeretin prevented the activation of JNK signaling pathway in OGD-stimulated HBMECs. Taken together, our current study demonstrated that tangeretin could ameliorate OGD-induced HBMECs injury through the JNK signaling pathway. Thus, tangeretin might be used as a therapeutic strategy for ischemia-reperfusion brain injury and related diseases.

Nurr1 exacerbates cerebral ischemia-reperfusion injury via modulating YAP-INF2-mitochondrial fission pathways

Nurr1, a nuclear transcription factor, has been linked to ischemia-reperfusion injury (IRI) in heart and kidney via modulating mitochondrial homeostasis. However, its role in cerebral ischemia-reperfusion has not been defined. In the present study, we found that cerebral IRI significantly increased the expression of Nurr1 and genetic ablation of Nurr1 attenuated the infarction area and reduced the neuron apoptosis under brain IRI burden. Functional studies have demonstrated that Nurr1 induced neuron death via activating mitochondrial fission. Aberrant mitochondrial fission promoted mitochondrial membrane potential reduction, evoked cellular oxidative stress and activated caspase-9-dependent mitochondrial apoptotic pathway. Interestingly, Nurr1 deletion alleviated fission-mediated mitochondrial damage, sustaining mitochondrial homeostasis and favoring neuron survival. Further, we found that Nurr1 deletion modulated mitochondrial fission via preventing INF2 upregulation in a manner dependent on YAP pathways. Either pharmacological blockade of YAP pathway or overexpression of INF2 abrogated the inhibitory effect of Nurr1 deletion on mitochondrial fission, leading to neuron death via mitochondrial apoptosis. Altogether, our results report that the pathogenesis of cerebral ischemia-reperfusion injury is associated with Nurr1 upregulation followed by augmented mitochondrial fission via an abnormal YAP-INF2 pathways.

NR4A1 Promotes Cerebral Ischemia Reperfusion Injury by Repressing Mfn2-Mediated Mitophagy and Inactivating the MAPK-ERK-CREB Signaling Pathway.

Mitochondrial dysfunction has been acknowledged as the key pathogenic mechanism in cerebral ischemia-reperfusion (IR) injury. Mitophagy is the protective system used to sustain mitochondrial homeostasis. However, the upstream regulator of mitophagy in response to brain IR injury is not completely understood. Nuclear receptor subfamily 4 group A member 1 (NR4A1) has been found to be associated with mitochondrial protection in a number of diseases. The aim of our study is to explore the functional role of NR4A1 in cerebral IR injury, with a particular focus on its influence on mitophagy. Wild-type mice and NR4A1-knockout mice were used to generate cerebral IR injury in vivo. Mitochondrial function and mitophagy were detected via immunofluorescence assays and western blotting. Cellular apoptosis was determined via MTT assays, caspase-3 activity and western blotting. Our data revealed that NR4A1 was significantly increased in the reperfused brain tissues. Genetic ablation of NR4A1 reduced the cerebral infarction area and repressed neuronal apoptosis. The functional study demonstrated that NR4A1 modulated cerebral IR injury by inducing mitochondrial damage. Higher NR4A1 promoted mitochondrial potential reduction, evoked cellular oxidative stress, interrupted ATP generation, and initiated caspase-9-dependent apoptosis. Mechanistically, NR4A1 induced mitochondrial damage by disrupting Mfn2-mediated mitophagy. Knockdown of NR4A1 elevated Mfn2 expression and therefore reversed mitophagic activity, sending a prosurvival signal for mitochondria in the setting of cerebral IR injury. Further, we demonstrated that NR4A1 modulated Mfn2 expression via the MAPK-ERK-CREB signaling pathway. Blockade of the ERK pathway could abrogate the permissive effect of NR4A1 deletion on mitophagic activation, contributing to neuronal mitochondrial apoptosis. Overall, our results demonstrate that the pathogenesis of cerebral IR injury is closely associated with a drop in protective mitophagy due to increased NR4A1 through the MAPK-ERK-CREB signaling pathway.

Cognitive Deficits Are Attenuated in Neuroglobin Overexpressing Mice Exposed to a Model of Obstructive Sleep Apnea.

Background: Obstructive sleep apnea (OSA) is a highly prevalent disease manifesting as intermittent hypoxia during sleep (IH) and is increasingly recognized as being independently associated with neurobehavioral deficits. These deficits may be due to increased apoptosis in the hippocampus and cerebral cortex, as well as increased oxidative stress and inflammation. It has been reported that neuroglobin (Ngb) is upregulated in response to hypoxia-ischemia insults and exhibits a protective role in ischemia-reperfusion brain injury. We hypothesized that transgenic overexpression of Ngb would attenuate spatial learning deficits in a murine model of OSA.Methods:Wild-type mice and Ngb overexpressing male mice (Ngb-TG) were randomly assigned to either IH or room air (RA) exposures. The effects of IH during the light period on performance in a water maze spatial task were assessed, as well as anxiety and depressive-like behaviors using elevated plus maze (EPM) and forced swim tests. Cortical tissues from all the mice were extracted for biochemical studies for lipid peroxidation.Results:Ngb TG mice exhibited increased Ngb immunoreactivity in brain tissues and IH did not elicit significant changes in Ngb expression in either Ngb-TG mice or WT mice. On a standard place training task in the water maze, Ngb-TG mice displayed preserved spatial learning, and were protected from the reduced spatial learning performances observed in WT mice exposed to IH. Furthermore, anxiety and depression levels were enhanced in WT mice exposed to IH as compared to RA controls, while alterations emerged in Ngb-TG mice exposed to IH. Furthermore, WT mice, but not Ngb-TG mice had significantly elevated levels of malondialdehyde in cortical lysates following IH exposures.Conclusions:In a murine model of OSA, oxidative stress responses and neurocognitive and behavioral impairments induced by IH during sleep are attenuated by the neuroprotective effects of Ngb.

P-300 - Reactive oxygen species production by brain mitochondria depends linearly on oxygen level

Reactive oxygen species (ROS) are by-products of physiological mitochondrial metabolism involved in several cellular signaling pathways and pathophysiological processes, including brain ischemia-reperfusion injury. The mitochondrial respiratory chain is considered a major source of ROS; however, there is a lack of agreement on how ROS release depends on oxygen concentration. We determined how the rate of H2O2 release by intact mouse brain mitochondria oxidizing different substrates depends on oxygen concentrations. The highest rate of H2O2 release occurs in conditions of reverse electron transfer, with complex I flavin as a major source of ROS generation. Our data indicate that the rate of H2O2 release by respiring mitochondria is linearly dependent on oxygen concentration. We also found that complex II can significantly contribute to ROS generation when the quinone pool is reduced even in the absence of its substrate succinate. Our results underscore the critical importance of reverse electron transfer in brain, where a significant accumulation of succinate during ischemia favors a backflow of electrons to complex I at the early stages of reperfusion. Our study also demonstrates that in brain tissue mitochondria ROS generation under hypoxic conditions is lower than in normoxia.

18F]-GE-179 positron emission tomography (PET) tracer for N-methyl-d-aspartate receptors: One-pot synthesis and preliminary micro-PET study in a rat model of MCAO

IntroductionThe objective of this study was to synthesize an N-methyl-d-aspartate receptor (NMDAR) radiotracer [18F]-GE-179 in one-pot and evaluate its in vivo binding for NMDAR activation after brain ischemia reperfusion injury. Methods[18F]-GE-179 was auto-synthesized using a quick one-pot method from a stable disulfide precursor and purified using semi-preparative high-performance liquid chromatography (HPLC) with ethanol/aqueous NaH2PO4 as the eluent. Dynamic micro-positron emission tomography (PET)/computed tomography (CT) study of [18F]-GE-179 was successfully performed using a rat model of middle cerebral artery occlusion (MCAO, induced by transient occlusion into the left MCA). A simplified reference tissue model method was used to calculate the [18F]-GE-179 non-displaceable binding potential (BPND) for intracranial NMDAR activation assessment. Immunofluorescence staining of NMDAR NR1 subunit in brain slices containing lesion was also performed. Results[18F]-GE-179 was successfully prepared in a yield of 23–30% in a formulation that could be injected directly after dilution. Localized radioactivity accumulation was observed in the animal model of MCAO. Significantly higher (p = 0.0003–0.0404) BPND relative to equivalent contralateral was found in the ipsilateral caudate putamen, Acb core/shell, cortex cingulate, amygdala, hypothalamus, and superior colliculus. Immunofluorescence staining showed elevated NMDAR expression in the affected hemisphere. Conclusions[18F]-GE-179 was synthesized using a one-pot process with a markedly improved yield. Preliminary in vivo micro-PET study visualized excessive NMDAR stimulation successfully in a rodent model of MCAO, which was consistent with results of in vitro immunofluorescence staining. The study demonstrates that [18F]-GE-179 is a promising PET probe for the detection of functional NMDAR alterations.

Remote Ischemic Postconditioning for Ischemic Stroke

Background:Remote ischemic postconditioning (RIPostC) appears to protect distant organs from ischemia-reperfusion injury (IRI). However, cerebral protection results have remained inconclusive. In the present study, a meta-analysis was performed to compare stroke patients with and without RIPostC.Methods:CNKI, WanFang, VIP, CBM, PubMed, and Cochrane Library databases were searched up to July 2016. Data were analyzed using both fixed-effects and random-effects models by Review Manager. For each outcome, risk ratio (RR) and mean difference (MD) with 95% confidence interval (CI) were calculated.Results:A total of 13 randomized controlled trials that enrolled a total of 794 study participants who suffered from or are at risk for brain IRI were selected. Compared with controls, RIPostC significantly reduced the recurrence of stroke or transient ischemic attacks (RR = 0.37; 95% CI: 0.26–0.55; P < 0.00001). Moreover, it can reduce the levels of the National Institutes of Health Stroke Scale score (MD: 1.96; 95% CI: 2.18–1.75; P < 0.00001), modified Rankin Scale score (MD: 0.73; 95% CI: 1.20–0.25; P = 0.00300), and high-sensitivity C-reactive protein (MD: 4.17; 95% CI: 4.71–3.62; P < 0.00001) between the two groups. There was no side effect of RIPostC using tourniquet cuff around the limb on ischemic stroke treating based on different intervention duration.Conclusion:The present meta-analysis suggests that RIPostC might offer cerebral protection for stroke patients suffering from or are at risk of brain IRI.

High-Mobility Group Box 1-Induced Complement Activation Causes Sterile Inflammation.

High-mobility group box 1 (HMGB1), a well-known danger-associated molecular pattern molecule, acts as a pro-inflammatory molecule when secreted by activated immune cells or released after necrotic cell damage. HMGB1 binds to immunogenic bacterial components and augments septic inflammation. In this study, we show how HMGB1 mediates complement activation, promoting sterile inflammation. We show that HMGB1 activates the classical pathway of complement system in an antibody-independent manner after binding to C1q. The C3a complement activation product in human plasma and C5b-9 membrane attack complexes on cell membrane surface are detected after the addition of HMGB1. In an acetaminophen (APAP)-induced hepatotoxicity model, APAP injection reduced HMGB1 levels and elevated C3 levels in C1q-deficient mouse serum samples, compared to that in wild-type (WT) mice. APAP-induced C3 consumption was inhibited by sRAGE treatment in WT mice. Moreover, in a mouse model of brain ischemia–reperfusion injury based on middle cerebral arterial occlusion, C5b-9 complexes were deposited on vessels where HMGB1 was accumulated, an effect that was suppressed upon HMGB1 neutralization. We propose that the HMGB1 released after cell necrosis and in ischemic condition can trigger the classical pathway of complement activation to exacerbate sterile inflammation.

Letter to the Editor Regarding “Association Between Blood Glucose and Functional Outcome in Intracerebral Hemorrhage: A Systematic Review and Meta-analysis”

Research has shown that ischemic preconditioning reduced the severity of ischemia-reperfusion injury in brain in rats, we have a hypothesis that repeated brief ischemia has positive effects on peripheral nerve damage. This study was conducted to investigate the potential protective effects of repeated brief ischemia on peripheral nerve regeneration using a rat model of experimental sciatic nerve transection injury.Treatment groups (groups A–D) received repeated, brief ischemia every 1 day/2 days/3 days/7 days. After surgery for 4, 8, 12 weeks, we evaluated sciatic functional index test, gastrocnemius muscle wet mass, axon and nerve fiber diameter, density, G-ratio, immunohistochemistry of S-100, vascular endothelial growth factor (VEGF), and the ultrastructure of the nerves.Sciatic functional index test and muscle wet mass were improved on the repeated brief ischemia groups. Ischemia treatment resulted in a significant increase in axon and nerve fiber density as well as S-100 and VEGF-positive cell, which indicated that repeated brief ischemia promotes Schwann cell proliferation and reconstruction.This study exhibits the positive effects of repeated brief ischemia in sciatic nerve transection injury, possibly in part because it can improve VEGF and the physiologic state of Schwann cells in the ischemic environment and then accelerate the ability of neurite outgrow.

Tnfrsf12a-Mediated Atherosclerosis Signaling and Inflammatory Response as a Common Protection Mechanism of Shuxuening Injection Against Both Myocardial and Cerebral Ischemia-Reperfusion Injuries.

Shuxuening injection (SXNI) is a widely prescribed herbal medicine of Ginkgo biloba extract (EGB) for cerebral and cardiovascular diseases in China. However, its curative effects on ischemic stroke and heart diseases and the underlying mechanisms remain unknown. Taking an integrated approach of RNA-seq and network pharmacology analysis, we compared transcriptome profiles of brain and heart ischemia reperfusion injury in C57BL/6J mice to identify common and differential target genes by SXNI. Models for myocardial ischemia reperfusion injury (MIRI) by ligating left anterior descending coronary artery (LAD) for 30 min ischemia and 24 h reperfusion and cerebral ischemia reperfusion injury (CIRI) by middle cerebral artery occlusion (MCAO) for 90 min ischemia and 24 h reperfusion were employed to identify the common mechanisms of SXNI on both cerebral and myocardial ischemia reperfusion. In the CIRI model, ischemic infarct volume was markedly decreased after pre-treatment with SXNI at 0.5, 2.5, and 12.5 mL/kg. In the MIRI model, pre-treatment with SXNI at 2.5 and 12.5 mL/kg improved cardiac function and coronary blood flow and decreased myocardial infarction area. Besides, SXNI at 2.5 mL/kg also markedly reduced the levels of LDH, AST, CK-MB, and CK in serum. RNA-seq analysis identified 329 differentially expressed genes (DEGs) in brain and 94 DEGs in heart after SXNI treatment in CIRI or MIRI models, respectively. Core analysis by Ingenuity Pathway Analysis (IPA) revealed that atherosclerosis signaling and inflammatory response were top-ranked in the target profiles for both CIRI and MIRI after pre-treatment with SXNI. Specifically, Tnfrsf12a was recognized as an important common target, and was regulated by SXNI in CIRI and MIRI. In conclusion, our study showed that SXNI effectively protects brain and heart from I/R injuries via a common Tnfrsf12a-mediated pathway involving atherosclerosis signaling and inflammatory response. It provides a novel knowledge of active ingredients of Ginkgo biloba on cardio-cerebral vascular diseases in future clinical application.

An Experimental Study on Repeated Brief Ischemia in Promoting Sciatic Nerve Repair and Regeneration in Rats.

Research has shown that ischemic preconditioning reduced the severity of ischemia-reperfusion injury in brain in rats, we have a hypothesis that repeated brief ischemia has positive effects on peripheral nerve damage. This study was conducted to investigate the potential protective effects of repeated brief ischemia on peripheral nerve regeneration using a rat model of experimental sciatic nerve transection injury. Treatment groups (groups A-D) received repeated, brief ischemia every 1 day/2 days/3 days/7 days. After surgery for 4, 8, 12 weeks, we evaluated sciatic functional index test, gastrocnemius muscle wet mass, axon and nerve fiber diameter, density, G-ratio, immunohistochemistry of S-100, vascular endothelial growth factor (VEGF), and the ultrastructure of the nerves. Sciatic functional index test and muscle wet mass were improved on the repeated brief ischemia groups. Ischemia treatment resulted in a significant increase in axon and nerve fiber density as well as S-100 and VEGF-positive cell, which indicated that repeated brief ischemia promotes Schwann cell proliferation and reconstruction. This study exhibits the positive effects of repeated brief ischemia in sciatic nerve transection injury, possibly in part because it can improve VEGF and the physiologic state of Schwann cells in the ischemic environment and then accelerate the ability of neurite outgrow.

Application of PeriCam PSI blood flow imaging perfusion system in rat brain ischemia reperfusion injury models

: To study the feasibility and effect of PeriCam PSI system guiding the establishment of ischemia/reperfusion injury model in rats. : A total of 70 adult male Sprague-Dawley rats were divided into the control group(n=6), PSI monitoring group(n=34) and traditional operation group(n=30). Ischemia reperfusion model was established with reference to improve Zea-Longa line plug method. After the model established, the blood flow to the brain of control group, PSI monitoring group (ischemic 2 h, 24 h reperfusion) were observed and recorded respectively with PSI. The rats were then executed after 24 h, and the 2,3,5-triphenyltetrazolium chloride (TTC) staining and HE staining were used to observe the brain tissue. : The survival rate and modeling success rate of PSI monitoring group were higher than those of the traditional operation group(all P<0.05). The blood perfusion in the brain and the distribution of blood vessels were clearly observed in the control group, and the data were normal. In 2 h ischemic group, the arterial flow was interrupted in the right cerebral artery, and the blood flow in the middle arterial blood supply was significantly decreased than that in the control group(P<0.05). After the recovery of 24 h, the artery in the right side of the brain was restored to blood flow, but the blood flow in the partial supply area decreased, unable to recover to normal level. The TTC staining results indicated that there were obvious infarcts in the right brain tissue of PSI monitoring group,and the infarct area was more stable than that of the traditional operation group. The results of HE staining showed that the structure of brain tissue in the control group was normal, and the morphological rules of nerve cells were not change. While in brain tissue from PSI monitoring group, cortex and ischemia half dark stripe, nerve cell degeneration, necrosis and glial fiber disintegration, liquefaction, and light color, screen mesh in ischemic central area were observed. : PSI system can guide ischemia reperfusion model building and improve the success rate of the model.

Magnolol protects against ischemic-reperfusion brain damage following oxygen-glucose deprivation and transient focal cerebral ischemia.

In the present study, the neuroprotective potential of magnolol against ischemia-reperfusion brain injury was examined via invivo and invitro experiments. Magnolol exhibited strong radical scavenging and antioxidant activity, and significantly inhibited the production of interleukin‑6, tumor necrosis factor‑a and nitrite/nitrate (NOX) in lipopolysaccharide-stimulated BV2 and RAW264.7 cells when applied at concentrations of 10 and 50µM, respectively. Magnolol (100µM) also significantly attenuated oxygen‑glucose deprivation‑induced damage in neonatal rat hippocampal slice cultures, when administered up to 4h following the insult. In a rat model of stable ischemia, compared with a vehicle‑treated ischemic control, pretreatment with magnolol (0.01‑1mg/kg, intravenously) significantly reduced brain infarction following ischemic stroke, and post‑treatment with magnolol (1mg/kg) remained effective and significantly reduced infarction when administered 2h following the onset of ischemia. Additionally, magnolol (0.3 and 1mg/kg) significantly reduced the accumulation of superoxide anions at the border zones of infarction and reduced oxidative damage in the ischemic brain. This was assessed by measuring the levels of NOX, malondialdehyde and myeloperoxidase, the ratio of glutathione/oxidized glutathione and the immunoreactions of 8‑hydroxy‑2'‑deoxyguanosine and 4‑hydroxynonenal. Thus, magnolol was revealed to protect against ischemia‑reperfusion brain damage. This may be partly attributed to its antioxidant, radical scavenging and anti‑inflammatory effects.

Erythropoietin Pretreatment Effect on Blood Glucose and Its Relationship With Inflammatory Factors After Brain Ischemic-Reperfusion Injury in Rats.

Introduction:Brain Ichemic-Reperfusion Injury (IRI) activates different pathophysiological processes. It also changes physiological parameters such as Blood Glucose (BG) level. An increase in BG after stroke is associated with poor clinical outcomes. Erythropoietin has been shown to be effective on both reducing inflammation and BG level. Therefore, in this study the erythropoietin pretreatment effect on BG and its relationship with inflammatory markers after brain IRI was investigated.Methods:Thirty adult male Wistar rats were randomly divided into 5 groups: sham, control and 3 pretreatment groups: single dose, double dose, and triple dose that received 1000 U/kg of erythropoietin before stroke induction in different times intraperitoneally. A rat model of IRI was established by Middle Cerebral Artery Occlusion (MCAO) for 60 minutes. Infarct volume, neurological defects, Interleukin-1α (IL-1α) and IL-6 serum levels were evaluated 24 hours after reperfusion. Also BG was measured after 1, 6, and 24 hours.Results:Single dose of erythropoietin significantly decreased infarct volume and improved neurological defects which was associated with decreased serum level of IL-1α and IL-6 but higher doses of erythropoietin administration had adverse effects on histological, neurological, and inflammatory results. In addition, erythropoietin significantly increased BG in a dose-dependent manner.Conclusion:Erythropoietin could reduce brain IRI by reducing inflammation and BG stabilization. The results of the present study demonstrated a relationship between inflammatory factors and hyperglycemia after IRI and suggested that erythropoietin may be useful for preventing brain IRI, but its higher doses should be used with caution due to possible side effects.