Experimental Cerebral Ischemia-reperfusion Research Articles

Critical role of Slc22a8 in maintaining blood-brain barrier integrity after experimental cerebral ischemia-reperfusion.

Blood-brain barrier (BBB) damage significantly affects the prognosis of ischemic stroke patients. This project employed multi-omics analysis to identify key factors regulating BBB disruption during cerebral ischemia-reperfusion. An integrated analysis of three transcriptome sequencing datasets from mouse middle cerebral artery occlusion/reperfusion (MCAO/R) models identified eight downregulated genes in endothelial cells. Additionally, transcriptome analysis of BBB (cortex) and non-BBB (lung) endothelium of E13.5 mice revealed 2,102 upregulated genes potentially associated with BBB integrity. The eight downregulated genes were intersected with the 2,102 BBB-related genes and mapped using single-cell RNA sequencing data, revealing that solute carrier family 22 member 8 (Slc22a8) is specifically expressed in endothelial cells and pericytes and significantly decreases after MCAO/R. This finding was validated in the mouse MCAO/R model at both protein and mRNA levels in this study. External overexpression of Slc22a8 using a lentivirus carrying Tie2 improved Slc22a8 and tight junction protein levels and reduced BBB leakage after MCAO/R, accompanied by Wnt/β-catenin signaling activation. In conclusion, this study suggested that MCAO/R-induced downregulation of Slc22a8 expression may be a crucial mechanism underlying BBB disruption. Interventions that promote Slc22a8 expression or enhance its function hold promise for improving the prognosis of patients with cerebral ischemia.

Ethanolic extract of Arctium lappa leaves alleviates cerebral ischemia reperfusion-induced inflammatory injury via HDAC9-mediated NF-κB pathway

BackgroundIschemic stroke (IS) is a major cause of mortality and disability worldwide. Inflammatory response is crucial in the pathogenesis of tissue injury in cerebral infarction. Arctium lappa leaves are traditionally used to treat IS. PurposesTo investigate the neuroprotective effects and molecular mechanisms of the ethanolic extract of A. lappa leaves (ALLEE) on cerebral ischemia-reperfusion (CIR). MethodsMiddle cerebral artery obstruction reperfusion (MCAO/R) rats and an oxygen-glucose deprivation/reoxygenation (OGD/R) cell model were used to evaluate ALLEE pharmacodynamics. Various methods, including neurological function, 2,3,5-triphenyltetrazolium chloride, hematoxylin and eosin, and Nissl, enzyme-linked immunosorbent, and TdT-mediated dUTP nick-end labeling assays, were used to analyze the neuroprotective effects of ALLEE in vitro and in vivo. The major chemical components and potential target genes of ALLEE were screened using network pharmacology. Molecular docking, western blotting, and immunofluorescence analyses were performed to confirm the effectiveness of the targets in related pathways. ResultsALLEE exerted potent effects on the MCAO/R model by decreasing the neurological scores, infarct volumes, and pathological features (p < 0.01). Furthermore, network pharmacology results revealed that the treatment of IS with ALLEE involved the regulation of various inflammatory pathways, such as the tumor necrosis factor (TNF) and chemokine signaling pathways. ALLEE also played key roles in targeting key molecules, including nuclear factor (NF)-κBIA, NF-κB1, interleukin (IL)-6, TNF-α and IL1β, and regulating the histone deacetylase (HDAC)-9-mediated signaling pathway. In vivo and in vitro analyses revealed that ALLEE significantly regulated the NF-κB pathway, promoted the phosphorylation activation of NF-κB P65, IκB and IKK (p < 0.01 or p < 0.05), and decreased the expression levels of the inflammatory factors, IL-1β, IL-6 and TNF-α (p < 0.01). Moreover, ALLEE significantly decreased the expression of HDAC9 (p < 0.01) that is associated with inflammatory responses. However, HDAC9 overexpression partially reversed the neuroprotective effects of ALLEE and its suppressive effects on inflammation and phosphorylation of NF-κB (p < 0.01). ConclusionsIn conclusion, our results revealed that ALLEE ameliorates MCAO/R-induced experimental CIR by modulating inflammatory responses via the inhibition of HDAC9-mediated NF-κB pathway.

Neuroprotective effects of the combined treatment of resveratrol and urapidil in experimental cerebral ischemia-reperfusion injury in rats.

To evaluate the neuroprotective effect of resveratrol, urapidil, and a combined administration of these drugs against middle cerebral artery occlusion (MCAO) induced ischemia/reperfusion (IR) injury model in rats. Thirty-five rats were divided into five groups of seven animals each. Animals in IR, IR resveratrol (IRr), IR urapidil (IRu), and IR + combination of resveratrol and urapidil (IRc) were exposed to MCAO induced cerebral ischemia reperfusion injury model. Rats in IRr and IRu groups received 30-mg/kg resveratrol and 5-mg/kg urapidil respectively. Animals in IRc received a combined treatment of both drugs. At the end of the study, brain tissues were used for oxidative stress (malondialdehyde, glutathione, and superoxide dismutase), pro-apoptotic caspase-3, anti-apoptotic Bcl-2, and pro-inflammatory tumor necrosis factor-α cytokine level measurements. The MCAO model successfully replicated IR injury with significant histopathological changes, elevated tissue oxidative stress, and upregulated apoptotic and inflammatory protein expression in IR group compared to control group (p < 0.001). All parameters were significantly alleviated in IRr group compared to IR group (all p < 0.05). In IRu group, all parameters except for caspase-3 and Bcl-2 were also significantly different than IR group (all p < 0.05). The IRc group showed the biggest difference compared to IR group in all parameters (all p < 0.001). The IRc had higher superoxide dismutase and Bcl-2 levels, and lower caspase-3 levels compared to both IRr and IRu groups (all p < 0.05). Also, the IRc group had lower MDA and TNF-α levels compared to IRu group (all p < 0.05). The results indicate that combined treatment of resveratrol and urapidil may be a novel strategy to downregulate neurodegeneration in cerebral IR injury.

Downregulation of Nrp1 transcription promotes blood–brain barrier disruption following experimental cerebral ischemia–reperfusion

Disruption of the blood–brain barrier (BBB) following cerebral ischemia–reperfusion injury (CIRI) is a major factor in the pathophysiology of stroke. Endothelial cell–cell communication is essential for maintaining BBB integrity. By analyzing GSE227651 data, we found that a decrease in endothelial cell–cell communication mediated by Sema3/Nrp1 may be due to the downregulation of Nrp1 transcription, which could contribute to BBB breakdown after CIRI. We confirmed this hypothesis by using western blot analysis to show a reduction in Nrp1 protein levels in penumbra endothelial cells after CIRI in mice. We then overexpressed Nrp1 specifically in brain endothelial cells using adeno-associated virus in mice. Furthermore, Nrp1 overexpression had a protective effect on BBB integrity, as evidenced by a decrease in IgG and albumin leakage caused by CIRI in mice. Finally, we found that Nrp1 overexpression also reduced brain cell death and neurological deficits induced by cerebral ischemia–reperfusion in mice. Our findings suggest that Nrp1 downregulation may be a key factor in the breakdown of endothelial cell–cell communication and subsequent BBB disruption following CIRI. Targeting Nrp1-mediated pathways may be a promising approach for mitigating BBB damage and alleviating neurological consequences in stroke patients.

Hyperperfusion profiles after recanalization differentially associate with outcomes in a rat ischemic stroke model

Futile recanalization hampers prognoses of ischemic stroke after successful mechanical thrombectomy, hypothetically through post-recanalization perfusion deficits, onset-to-groin delays and sex effects. Clinically, acute multiparametric imaging studies remain challenging. We assessed possible relationships between these factors and disease outcome after experimental cerebral ischemia-reperfusion, using translational MRI, behavioral testing and multi-model inference analyses. Male and female rats (N = 60) were subjected to 45-/90-min filament-induced transient middle cerebral artery occlusion. Diffusion, T2- and perfusion-weighted MRI at occlusion, 0.5 h and four days after recanalization, enabled tracking of tissue fate, and relative regional cerebral blood flow (rrCBF) and -volume (rrCBV). Lesion areas were parcellated into core, salvageable tissue and delayed injury, verified by histology. Recanalization resulted in acute-to-subacute lesion volume reductions, most apparently in females (n = 19). Hyperacute normo-to-hyperperfusion in the post-ischemic lesion augmented towards day four, particularly in males (n = 23). Tissue suffering delayed injury contained higher ratios of hypoperfused voxels early after recanalization. Regressed against acute-to-subacute lesion volume change, increased rrCBF associated with lesion growth, but increased rrCBV with lesion reduction. Similar relationships were detected for behavioral outcome. Post-ischemic hyperperfusion may develop differentially in males and females, and can be beneficial or detrimental to disease outcome, depending on which perfusion parameter is used as explanatory variable.

Role of Rph3A in brain injury induced by experimental cerebral ischemia-reperfusion model in rats.

AimThe aim was to study the role of Rph3A in neuronal injury induced by cerebral ischemia‐reperfusion.MethodsThe protein and mRNA levels of Rph3A in penumbra were detected by Western blot. The localization of Rph3A in different cell types in penumbra was detected by immunofluorescence. Apoptosis in the brain was detected by TUNEL staining. We tested neurobehavioral evaluation using rotarod test, adhesive‐removal test, and Morris Water maze test. We examined the expression and localization of Rph3A in cultured neurons and astrocytes in vitro by Western blot and ELISA, respectively.ResultsThe mRNA and protein levels of Rph3A had significantly increased in brain penumbra of the rat MCAO/R model. Rph3A was mainly distributed in neurons and astrocytes and was significantly increased by MCAO/R. We downregulated Rph3A and found that it further worsened the cerebral infarct, neuronal death and behavioral, cognitive, and memory impairments in rats after MCAO/R. We also found that ischemia‐reperfusion upregulated the in vitro protein level and secretion of Rph3A in astrocytes but led to a decrease in the protein level of Rph3A in neurons.ConclusionThe increase in Rph3A in the brain penumbra may be an endogenous protective mechanism against ischemia‐reperfusion injury, which is mainly dominated by astrocytes.

Effects of amantadine and topiramate on neuronal damage in rats with experimental cerebral ischemia-reperfusion.

Ischemia-reperfusion models are used to evaluate treatment options that may minimize cellular damage after ischemia. To investigate the effects of amantadine and topiramate on apoptosis and cellular oxidative damage. This experiment was performed using 30 male Wistar albino rats. The right internal carotid artery was identified and clamped with an aneurysm clip under general anesthesia, except for animals in the control group. After 10 min of occlusion, the aneurysm clip was removed, allowing reperfusion. After reperfusion and a waiting period of 12 h, the test and control groups were intraperitoneally administered the following solutions: the sham group received 10 mg/kg of isotonic solution, the amantadine group received 20 mg/kg of amantadine, the topiramate group received 40 mg/kg of topiramate, and the amantadine-topiramate group received 20 mg/kg of amantadine and 40 mg/kg of topiramate. After 24 h, the rats were euthanized. Apoptosis was evaluated using the TUNEL method. Total antioxidant status (TAS), total oxidant status (TOS), total thiol, and ischemia-modified albumin (IMA) levels were measured in both brain tissue and serum samples. The rate of apoptosis in the sham and amantadine groups increased significantly compared to the control group and the non-ischemic counter hemisphere. In the amantadine-topiramate group, both serum TAS and tissue thiol levels decreased. Tissue TOS levels were significantly higher in the topiramate group compared to all other test groups. Tissue TAS levels were significantly higher in the amantadine group compared to all other test groups. This experimental ischemia-reperfusion model revealed that topiramate reduces apoptosis in the early period after ischemia and that its combination with amantadine does not provide additional benefits against cell death. However, topiramate did not have an inhibitory effect on the oxidative stress biomarkers used in our study (TAS, TOS, IMA, and thiol). Studies that reveal the neuroprotective mechanism of action and long-term effects of topiramate are needed to complement this study.

Neuroprotective Influence of miR-301a Inhibition in Experimental Cerebral Ischemia/Reperfusion Rat Models Through Targeting NDRG2.

The objective of this study is to find out the potential influence of miR-301a in an experimental cerebral ischemia-reperfusion (I/R) rat model through targeting NDRG2. Rats with cerebral I/R injury were constructed and classified into model, miR-301a inhibitor, miR-301a mimic, NC (negative control), siNDRG2, NDRG2, and miR-301a inhibitor + si-NDRG2 groups, as well as another sham group. Cerebral infarct volume and cell apoptosis were observed by TTC staining and TUNEL staining. The targeting relationship between miR-301a and NDRG2 was verified by luciferase assay. ELISA, qRT-PCR, and Western blot were used to detect the expressions of related molecules. Compared with sham group, rats in the model group had elevated neurological function score and infarct volume; meanwhile, the cell apoptosis rate and inflammatory response were also increased with enhanced expression of miR-301a and NDRG2 (all P < 0.05). These changes were worsened in the miR-301a mimic and si-NDRG2 groups. Conversely, those rats in the miR-301a inhibitor and NDRG2 groups presented increased NDRG2, and at the same time, other above concerning factors also exhibited opposite tendencies (all P < 0.05). Dual-luciferase reporter gene assay confirmed that NDRG2 was a target gene of miR-301a, and si-NDRG2 could reverse the neuroprotective effect of miR-301a inhibitor in rats with cerebral I/R injury. Inhibiting miR-301a has a neuroprotective effect on rats with cerebral I/R injury to ameliorate cell apoptosis and inflammatory response through possibly targeting NDRG2.

All-Trans Retinoic Acid Ameliorates the Early Experimental Cerebral Ischemia-Reperfusion Injury in Rats by Inhibiting the Loss of the Blood-Brain Barrier via the JNK/P38MAPK Signaling Pathway.

All-trans retinoic acid (ATRA) influences the outcomes of cerebral ischemic reperfusion (CIR) injury, but the mechanism remains unclear. The present study aimed to investigate the effects of ATRA on loss of the blood brain barrier (BBB) following CIR and to explore the possible mechanisms. Transient middle cerebral artery occlusion was performed on male SD rats to construct an in vivo CIR model. Neurological deficits, BBB permeability, brain edema, MRI and JNK/P38 MAPK proteins were detected at 24h following CIR. We demonstrated that ATRA pretreatment could alleviate CIR-induced neurological deficits, increase of BBB permeability, infarct volume, degradation of tight junction proteins, inhibit MMP-9 protein expression and activity. ATRA treatment also reduced the p-P38 and p-JNK protein level. However the protective effect of ATRA on CIR could be reversed by administration of retinoic acid alpha receptor antagonist Ro41-5253. SP600125 and SB203580, which is the JNK/P38 pathway inhibitors has the same protective effect as ATRA. These results indicated that ATRA may inhibit the JNK/P38 MAPK pathway to alleviate BBB disruption and improve CIR outcomes.

Limb remote ischemic post-conditioning mitigates brain recovery in a mouse model of ischemic stroke by regulating reactive astrocytic plasticity

Maladaptive alterations of astrocytic plasticity may cause brain edema in the acute stage of stroke and glial scar formation in the recovery stage. The present study was designed to investigate the potential regulation of limb remote ischemic post-conditioning (RIPC) on astrocytic plasticity in experimental cerebral ischemia-reperfusion injury. Cerebral ischemia was induced by transient middle cerebral artery occlusion (tMCAO) for 1 h in C57BL/6 mice, who were treated with RIPC immediately after reperfusion. The results showed that RIPC decreased hemispheric swelling, infarct volume and brain atrophy, and increased neurological function recovery and survival rates of ischemic mice at 3 and 14 d after cerebral ischemia-reperfusion, respectively. Moreover, the proportion of astrocyte subtypes was adjusted by RIPC treatment, demonstrated by decreased expression of the fibrous type (glial fibrillary acidic protein, GFAP) and increased expression of the protoplasmic type (glutamine synthetase, GS) in the ipsilateral side of the mouse brain at 14 d after cerebral ischemia-reperfusion. RIPC treatment adjusted the proportion of GFAP subtypes by downregulating the protein level of GFAPα, as well as upregulating the GFAPδ/GFAPα ratio in the ipsilateral side at 3 and 14 d after reperfusion. Notably, RIPC inhibited the phosphorylation of signal transducer and activators of transcriptions 3 (p-STAT3) in the ipsilateral side at 3 and 14 d after cerebral ischemia-reperfusion. Taken together, the results show that RIPC treatment could regulate reactive astrocytic plasticity and inhibition of STAT3 phosphorylation to promote neurological function recovery following ischemic stroke.

Platelet glycoprotein receptor Ib blockade ameliorates experimental cerebral ischemia–reperfusion injury by strengthening the blood–brain barrier function and anti-thrombo-inflammatory property

Blood-brain barrier (BBB) disruption, thrombus formation and immune-mediated inflammation are important steps in the pathophysiology of cerebral ischemia–reperfusion injury but are still inaccessible to therapeutic interventions. Recent studies have provided increasing evidence that blocking of platelet glycoprotein (GP) receptor Ib might represent a novel target in treating acute ischemic stroke. This research was conducted to explore the therapeutic efficacy and potential mechanisms of GPIbα inhibitor (anfibatide) in a model of brain ischemia–reperfusion injury in mice. Male mice underwent 90 min of right middle cerebral artery occlusion (MCAO) followed by 24 h of reperfusion. Anfibatide (1, 2, 4 ug/kg) or tirofiban were administered intravenously 1 h after reperfusion. The results showed that anfibatide could significantly reduce infarct volumes, increase the number of intact neuronal cells and improve neurobehavioral function. Moreover, anfibatide could reduce post ischemic BBB damage by attenuating increased paracellular permeability in the ischemia hemisphere significantly. Stroke-induced increases in activity and protein expression of macrophage-1 antigen (MAC-1) and P-selectin were also reduced by anfibatide intervention. Finally, anfibatide exerted antithrombotic effects upon stroke by decreased the number of microthrombi formation. This is the first demonstration of anfibatide’s efficacy in protecting the BBB integrity and decreasing neutrophil inflammation response mediated by MAC-1 besides microthrombus formation inhibition in the brain during reperfusion. Anfibatide, as a promising anti-thrombo-inflammation agent, could be beneficial for the treatment of ischemic stroke.

Evaluation of the protective potential of brain microvascular endothelial cell autophagy on blood-brain barrier integrity during experimental cerebral ischemia-reperfusion injury.

Brain microvascular endothelial cell (BMVEC) injury induced by ischemia-reperfusion (I/R) is the initial phase of blood-brain barrier (BBB) disruption, which results in a poor prognosis for ischemic stroke patients. Autophagy occurs in ischemic brain and has been shown to exhibit protective effects on endothelial cell against stress. However, the potential effects of BMVEC autophagy on BBB permeability during I/R and the mechanisms underlying these effects have yet to be elucidated. In the current study, we answered these questions by using chemical modulators of autophagy, including rapamycin and lithium carbonate acting, respectively, as mammalian target of rapamycin (mTOR)-dependent and mTOR-independent autophagy inducers and 3-methyladenine (3-MA) as an autophagy inhibitor. To mimic I/R injury, BMVECs were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R), and a rat transient middle cerebral artery occlusion/reperfusion (MCAO/R) model was performed. All the drugs were given at 0.5h before OGD/R or MCAO/R. First, enhancement of autophagy by rapamycin and lithium carbonate attenuated, whereas suppression of autophagy by 3-MA intensified BMVEC apoptosis and the high level of ROS induced by OGD/R. In addition, rapamycin and lithium carbonate pretreatments significantly reversed the decreased level of tight junction protein zonula occludens-1 (ZO-1) induced by OGD/R and promoted the distribution of ZO-1 on cell membranes. Finally, pretreatments with rapamycin and lithium carbonate reduced evans blue extravasation and brain water content in the ischemic hemisphere of the rat. In contrast, 3-MA pretreatment exerted opposite effects both in vitro and in vivo. These results may indicate a beneficial effect of BMVEC autophagy on BBB integrity during I/R injury.

Calycosin-7-O-β-d-glucoside regulates nitric oxide /caveolin-1/matrix metalloproteinases pathway and protects blood–brain barrier integrity in experimental cerebral ischemia–reperfusion injury

Ethnopharmacology relevanceAstragali Radix (AR) has been used for thousands years to treat ischemic stroke. Calycosin and its glycoside form calycosin-7-O-β-d-glucoside (CG) are two representative isoflavones in Astragali Radix. However, its neurological effects and related molecular mechanisms are largely unknown. The present study aims to evaluate the neuroprotective effects of CG on blood–brain barrier (BBB) integrity of ischemic brain tissue and explore the relevant signaling mechanisms. Material and methodMale adult Sprague-Daweley rats were subjected to 2h of middle cerebral artery occlusion (MCAO) plus 24h or 14 days of reperfusion. CG (26.8 mg/kg) was intraperitoneally administered into the rats at 15min before onset of ischemia. The neuroprotective effects of CG were evaluated by measuring infarct volume, histological damage and BBB permeability. Furthermore, the effects of CG on scavenging nitric oxide (NO), and modulating matrix metalloproteinases (MMPs) and caveolin-1 (cav-1) were investigated with in vitro cultured brain microvascular endothelial cells treated with NO donor or oxygen–glucose deprivation (OGD) and/or in vivo rat model of MCAO cerebral ischemia–reperfusion injury. ResultsCG treatment significantly reduced infarct volume, histological damage and BBB permeability in the in vivo MCAO ischemia–reperfusion rat model. CG treatment remarkably inhibited the expression and activities of MMPs, and secured the expression of cav-1 and tight junction proteins in the microvessels isolated from ischemic rat cortex. Furthermore, CG was revealed to scavenge NO, inhibit the activities of MMP-2 and MMP-9, and attenuate cell death in the in vitro cultured brain microvascular endothelial cells under OGD condition. ConclusionCG could protect BBB integrity in experimental cerebral ischemia–reperfusion injury via regulating NO/cav-1/MMPs pathway.

Protective Effect Of Bosentan In Experimental Cerebral Ischemia-Reperfusion Injury

OBJECTIVE: In cerebral ischemia, there are many factors that start the events leading to cell death. These factors contain free radical production, excitotoxicity, sodium and calcium flow disruption, enzymatic changes, stimulation of the inflamatuar process, the activation of platelets and leukocytes, delayed coagulation, endothelial dysfunction and endothelin (ET) release. Bosentan is the competitive antagonist of endothelin receptors; ETA and ETB. The aim of this study is to determine whether the protective effects of bosentan in experimental cerebral ischemia reperfusion injury. MATERIAL and METHODS: In this study, after ischemia-reperfusion procedure, bosentan molecule was regularly given to rats for 5 days. The brain tissues of decapitated rats were histopathologically examined. The levels of oxidant and antioxidant were determined in these brain tissues. RESULTS: It was observed that antioxidant levels and histopathological examinations were in rats given bosentan better than control group rats. CONCLUSION: In conclusion, this study has showed that bosentan may be an agent which could reduce negative effects resulting from neuronal death associated with ischemic stroke.

Cell and tissue damage in relation to apoptosis-linked molecules in experimental cerebral ischemia–reperfusion and traumatic spinal cord injury

A variety of acute insults to the CNS, either traumatic, ischemic or inflammatory, bring about the destruction of neural tissue, leaving permanent damage. The mode of cell loss and tissue damage in those settings is thought to be either necrotic or apoptotic. However, the terms, necrosis and apoptosis, appear not well defined in solid tissues like brain, as opposed to freely circulating cells. We have attempted to assess the significance of death-related molecules and apoptosis for ultimately forming a mass of dead neural tissue, utilizing two experimental models of the CNS insult, i.e., acute transection injury of the spinal cord and ischemia–reperfusion damage of the cerebral hemisphere. Apoptosis-related molecules utilized here included p53, p21, Bcl-2, Bax for spinal cord injury model and p53 and NF-κB for ischemia–reperfusion.

Alterations in superoxide dismutase, glutathione peroxidase and catalase activities in experimental cerebral ischemia-reperfusion.

Free radicals are thought to be the most important cause of the reperfusion injury subsequent to ischemia. The antioxidant status of the tissue affected by ischemia-reperfusion is of great importance for the primary endogenous defense against the free radical induced injury. This investigation was performed to evaluate the antioxidant enzyme capacity of the brain tissue in the ischemia-reperfusion period using an experimental global moderate (penumbral) ischemia model on rat brains. Experiments were performed on 45 male Sprague Dawley rats. Ischemia was induced by bilateral vertebral arteries cauterization and temporary bilateral carotid arteries occlusion and sustained for 10 minutes. At the end of ischemia (0 min reperfusion) and various reperfusion periods (20 min, 60 min, 240 min), rats were decapitated and brains were frozen in liquid nitrogen. Changes in the intracellular antioxidant enzyme (superoxide dismutase, glutathione peroxidase and catalase) activities were assessed in the rat brain tissues, by spectrophotometric methods. In all moderate ischemia-reperfusion groups, superoxide dismutase activities were found to have decreased significantly compared to the sham operated controls (P < 0.05). During ischemia superoxide dismutase activity was lowered to 31% of that of the control group. The decreases were more significant in reperfusion groups, particularly in 60 min reperfusion (40%). Relatively smaller but still significant diminution was observed in glutathione peroxidase activities (P < 0.05). The ratio of diminution was striking in 20 min and 60 min reperfusion groups with 26% of the sham operated rats. Conversely, moderate ischemia-reperfusion caused significant increase in catalase activities (P < 0.05). The increment was 63% of the preischemic level with 10 min of moderate ischemia. In conclusion, activities of the major antioxidant enzymes were changed significantly in moderate brain ischemia-reperfusion. These results suggest that the disturbance in oxidant-antioxidant balance might play a part in rendering the tissue more vulnerable to free radical induced injuries.

The Effect of 2-Chloroadenosine on Lipid Peroxide Level During Experimental Cerebral Ischemia–Reperfusion in Gerbils

Oxygen free radicals may be implicated in the pathogenesis of ischemia–reperfusion damage. It is known that 2-chloroadenosine (2-CADO) has neuromodulatory effects and prevents the neuronal damage seen in the period of postischemia reperfusion. However, direct effects of 2-CADO on lipid peroxidation have not been investigated previously. The attack on the cell membrane by free radicals leads to lipid peroxidation, which can be assayed by the malondialdehyde (MDA) level. The aim of this study was to determine the effect of 2-CADO therapy on lipid peroxidation in experimental forebrain ischemia and postischemia reperfusion in Mongolian gerbils. Cerebral ischemia was induced by a bilateral 30-mm occlusion of the common carotid arteries. 2-Chloroadenosine (0.6 mg/kg, IV) was administered 5 min subsequent to ischemia. Ischemia was followed by reperfusion for 30 min. The MDA level was measured by the thiobarbituric acid (TBA) test. Bilateral carotid artery occlusion for 30 min in gerbils resulted in no significant change in MDA level in the brain. The MDA level was higher in postischemia reperfusion than in the ischemic group. 2-Chloroadenosine treatment did not change the MDA level in the ischemic period. However, the MDA level recovered significantly upon 2-CADO therapy during reperfusion following ischemia. These results suggest that 2-CADO may offer some degree of protection against oxidative stress in cerebral ischemia–reperfusion damage. Copyright © 1996 Elsevier Science Inc.