Protective effect of spermine on rats with acute cerebral ischemia/reperfusion injury

AIM: To study the effects and the possible mechanisms of exogenous spermine on the rats with acute transient focal cerebral ischemia/reperfusion (I/R) injury.METHODS: The rat model of focal cerebral ischemia/reperfusion was established by middle cerebral artery occlusion (2 h) and reperfusion (2 h). Healthy adult SD rats were divided into 5 groups;sham group,I/R group and spermine(4,20 and 40 mmol/L)groups.The degree of cerebral injury was evaluated by neurological deficit score, infracted volume, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. The morphological changes of the brain were observed by HE staining and electron microscopy. RESULTS: Compared with I/R group, the neurological deficit score, infracted volume and the content of MDA were decreased, the SOD activity was increased and the ultrastructural changes were improved in spermine-treated groups. CONCLUSION: Exogenous spermine has a protective effect against acute focal cerebral ischemia/reperfusion injury. The mechanisms may be related to scavenging free radical by spermine.     

Production of nitric oxide and change of nitric oxide synthase activity in brains mitochondria of the rats with focal cerebral ischemia/reperfusion

AIM and METHOD:To determine the production of nitric oxide(NO) and change of NO synthase(NOS) activity in mitochondria isolated from the rat brains of the ischemia/reperfusion rat model produced by transient occlusion of middle cerebral artery on the following time points:2 h after occlusion of artery and 30 min,2 h, 4h after reperfusion.RESULTS:After the occlusion of middle cerebral artery,the respiratory control rate(RCR) of mitochondria significantly decreased and slightly increased at 4h after reperfusion.Meantime,the production of NO in mitochondria increased significantly.But with the increase of perfusion, production of NO gradually decreased and reached normal level as in the control group.It also shows that cerebral ischemia increased NOS's activity significantly in the mitochondria and still kept a higher level than the control group although it decreased gradually after reperfusion.But the iNOS's activity did not show obvious change.The change of total NOS's activity depends on the change of cNOS's activity.CONCLUSION: The activation of NO/NOS system in the mitochondria might play an important role in the reperfusion injury during reperfusion of ischemic brain.     

Mechanism of therapeutic effect of QingKaiLing-ingredient combination on focal cerebral ischemia-reperfusion injury

AIM:To elucidate the therapeutic effect and mechanism of QingKaiLing (QKL)-ingredient combination on cerebral ischemia. METHODS:Rat focal brain ischemia reperfusion injury was produced by occlusion in the middle cerebral artery. MRI and histological analysis were used to evaluate the brain injury induced by ischemia and the attenuations by the drugs including QKL-ingredient combination and the positive control nimodipine. In situ hybridization was used to measure the expression of BDNF mRNA in the brain. RESULTS:A significant neuroprotective effect was observed in the QKL-ingredient combination treatment group, which was superior to that in the nimodipine treatment group. The expression of BDNF mRNA in the brain was also significantly up-regulated by the QKL-ingredient combination treatment in a rat model of focal cerebral ischemia-reperfusion injury. CONCLUSION:The QKL ingredients show a neuro-protective effect, the mechanism may be related to the up-regulation of BDNF in the brain.     

Effects of ischemic preconditioning on oxidative stress and mitochondrial function in young and old rat myocardium with ischemia/reperfusion

AIM: To study the protective effect of ischemia preconditioning (IPC) on ischemia/reperfusion (IR)-damaged myocardium in young and old rats. METHODS: Male Wistar rats aged at 3 months (young) and 20 months (old) were used to establish myocardial IPC model and IR model with the method of Langendorff heart perfusion. The rats were divided into young ischemia/reperfusion (YIR) group, young ischemic preconditioning (YPC) group, old ischemia/reperfusion (OIR) group and old ischemic preconditioning (OPC) group. Transmission electron microscopy was used to observe the ultrastructural changes of myocardial tissue and myocardial mitochondria. The myocardial infarction area was determined by TTC staining. The lactate dehydrogenase (LDH) content in coronary effluent fluid and the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in myocardial tissues were detected by the method of colorimetry. The levels of nitrated and carbonylated proteins in myocardial tissue were measured by ELISA. The myocardial cell apoptosis was analyzed by TUNEL assay. The mitochondrial respiratory function and mitochondrial permeability transition pore opening induced by calcium load were evaluated by oxygen electrode method. RESULTS: Compared with YIR group, the myocardial infarction area in YPC group was obviously smaller, SOD activity in myocardial tissues increased, LDH activity in coronary effluent fluid and the content of MDA decreased, and the levels of nitrated and carbonylated proteins in the cardiac tissues reduced. In YPC group, the mitochondrial membrane structure appeared intact, cristae of the mitochondria showed close arrangement, and the matrix was compressed under the electron microscope. Myocardial mitochondrial respiratory control rate, state Ⅲ oxygen consumption and the P/O ratio in YIR group all significantly increased, proton leak decreased, mitochondrial swelling induced by calcium distinctly reduced, and myocardial apoptosis rate declined. No significant difference of the above indexes between OIR group and OPC group was observed. Compared with YPC group, myocardial ultrastructural damage increased clearly, cardiac oxidative stress increased, mitochondrial respiratory function declined, and cell apoptosis and necrosis increased in OPC group. CONCLUSION: Ischemic preconditioning has protective effect against myocardial IR injury in young rat hearts, while old rat hearts were less sensitive to ischemic preconditioning, leading to bluntness of cardioprotection with IPC in aging hearts. This may be related to mitochondrial injury and severe cellular apoptosis caused by increase of cardiac oxidative stress levels in the aging ischemic preconditioning heart.     

Protective effect of allitridi on hippocampus of rats with cerebral ischemia-reperfusion and P53 expression

AIM: To observe the protective effect of allitridi on hippocampal neuron of rats with cerebral ischemia-reperfusion (I/R) injury and to investigate its effects on P53 expression in hippocampus.METHODS: The global cerebral ischemia-reperfusion models were established by 4-vessel occlusion. Allitridi at doses of 10, 20 or 30 mg/kg was injected through rat’s tail vein, half dose at 30 min before brain ischemia and another half dose at 10 min after reperfusion were injected, respectively. The hippocampus of rat was removed 24 h after reperfusion. Toluidine blue staining was applied to estimate morphologic changes. Flow cytometry was used to evaluate neuronal apoptosis rate of hippocampus. Immunohistochemistry was used to observe the expression of P53 protein.RESULTS: Compared with sham group, survival neuronal density in I/R group was significantly depressed. The rate of neuronal apoptosis and the expression of P53 protein were significantly increased. Allitridi significantly increased the number of survival neurons in hippocampus compared to I/R group. Meanwhile, allitridi remarkably inhibited the rate of neuronal apoptosis and the expression of P53 protein.CONCLUSION: Allitridi has protective role against brain ischemia reperfusion injury. The mechanism may be involved in blocking P53 protein expression in hippocampus of rats with ischemia-reperfusion.     

Effects of Astragalus injection on neuronal apoptosis and expression of JNK3 in rat hippocampus after cerebral ischemia reperfusion

AIM:To investigate the effects of Astragalus injection on neuronal apoptosis and expression of c-Jun N-terminal kinase 3(JNK3) in the rat hippocampus after cerebral ischemia reperfusion. METHODS:The rat model of cerebral ischemia reperfusion was set up by a four-vessel occlusion method. The SD rats were randomly divided into 4 groups:sham operation group, cerebral ischemia reperfusion group(model group), cerebral ischemia reperfusion+Astragalus injection group(Astragalus injection group) and cerebral ischemia reperfusion+vehicle group(vehicle group). The rats in model group, Astragalus injection group and vehicle group after transient global cerebral ischemia(30 min) were then divided into 7 subgroups according to the reperfusion time of 0 h, 0.5 h, 2 h, 6 h, 24 h, 72 h and 120 h. The apoptosis of the neuron in the hippocampus was measured by the method of TUNEL staining. The expression of JNK3 at mRNA and protein levels was determined by real-time PCR and Western blotting,respectively. RESULTS:Compared with sham operation group, the number of apoptotic neurons increased in model group(P<0.05). Compared with model group, the number of apoptotic neurons decreased obviously in Astragalus injection group(P<0.05). Compared with sham operation group, the expression of JNK3 at mRNA and protein levels in the hippocampus increased obviously in model group at all time points except 120 h(P<0.05). Compared with model group, the expression of JNK3 at mRNA and protein levels in the hippocampus decreased obviously in Astragalus injection group at all time points except 120 h(P<0.05). CONCLUSION:Astragalus injection decreases neuronal apoptosis in rat hippocampus after cerebral ischemia reperfusion by inhibiting the expression of JNK3 at mRNA and protein levels.     

Neuronal damage and cell death following ischemia/reperfusion in diabetic rats

AIM:To study forms of cell death following cerebral ischemia/reperfusion in diabetic rats. METHODS:Based on the modles of diabetes and middle cerebral artery occlusion(MCAO), characteristics of cell death after ischemia/reperfusion were evaluated synthetically by the pathological, flow cytometry(FCM), TUNEL and the DNA agarose electrophoresis.RESULTS:The occurrence of cerebral injury after ischemia/reperfusion were accompanied by cell necrosis and cell apoptosis. And cell apoptosis was mainly located in ischeamic penumbra(IP) zone around the densely ischemic focus. Ischemic centre(IC)was characterized by cell necrosis. At the same time, the results showed that the process of ischemic cerebral injury worsen by diabetes mellitus was related to inducing cell apoptosis in IP and Mid zone.CONCLUSION:Neuronal damage following focal cerebral ischemia/reperfusion included cell necrosis and apoptosis, IC zone was mainly characterized by the former, however IP zone by the latter, and there had close internal relationship between them. Brain damage following cerebral ischemia/reperfusion was worsen instinctly under diabetic condition.     

Upregulative effect of CGRP on expression of CREB and phospho-CREB protein during focal cerebral ischemia/reperfusion in rat parietal cortex

AIM: To investigate the effect of calcitonin gene related peptide (CGRP) on the expression of cyclic AMP response element binding protein (CREB) and phosphorylated-CREB in rat parietal cortex during focal cerebral ischemia/reperfusion (I/R).METHODS: Focal cerebral ischemia/reperfusion model was induced by occlusion of the right middle cerebral artery using the intraluminal suture method. The expressions of CREB and phospho-CREB in the parietal cortex in different groups (sham group, focal cerebral ischemia/reperfusion group and CGRP group) were detected with immunohistochemistry and Western blotting, and the positive products were analyzed by image analysis system.RESULTS: There was definite expression of CREB in right parietal cortex in sham group, while it was lesser in I/R group than that in sham group, but it became more in CGRP group than that in I/R group (P<0.05). Phospho-CREB was barely detected in right parietal cortex in sham group and it became more in I/R group than that in sham group. The expression of phospho-CREB increased in CGRP group than that in I/R group of the right parietal cortex (P<0.05).CONCLUSION: CGRP upregulates the expression of CREB and phospho-CREB in the ischemic neurons of the parietal cortex during focal cerebral ischemia/reperfusion and CREB probably involves in the mechanism of protective role of CGRP to ischemic neurons.     

Changes of ceramide and apoptosis during myocardial ischemia/reperfusion

AIM: To study the change of myocardial ceramide during myocardial ischemia/reperfusion and the relationship between ceramide and apoptosis and oxidative stress. METHODS: After inducing myocardial ischemia/reperfusion (I/R) injury in mice with pituitrin (Pit), myocardial SOD activity and MDA content were measured. DNA agarose gel electrophoresis and fluorescent staining of DAPI were done to check up apoptosis. The content of myocardial ceramide (μg/kg) was measured through HPTLC and scan of thin plate. RESULTS: The myocardium of I/R model group had the phenomenon of DNA ladder. Apoptosis index and ceramide content in I/R model group were higher than those in normal control group (P<0.01). SOD activity in I/R modal group was lower than that in normal control group (P<0.01). The apoptosis index and ceramide content in I/R model group were positive correlative (r=0.970，P<0.01). The myocardial content of ceramide and MDA were positively correlative too (r=0.974, P<0.01). CONCLUSION: The results indicate that there are apoptosis, oxidative stress and increase in ceramide content in ischemia/reperfusion myocardium.     

Effect of cholecystokinin-octapeptide on focal cerebral ischemia/reperfusion injury in rats

AIM:To examine the effect of cholecystokinin-octapeptide (CCK-8) on focal cerebral ischemia/reperfusion injury and its underlying mechanisms.METHODS:By using the suture model of focal cerebral ischemia and reperfusion, the effects of intracerebroventricular (icv) injection of CCK-8 and proglumide, nonselective CCK receptors antagonist, on the infarct size, regional cerebral blood flow (rCBF), and the levels of nitric oxide (NO), malondialdehyde (MDA) were observed in different brain regions of rats subjected to 1 h focal cerebral ischemia followed by 24 h reperfusion.RESULTS:(1) pretreatment with different doses of CCK-8 (0.3 μg,1.0 μg,2.0 μg or 4.0 μg) could attenuate the infarct size, but the statistically significant effects of CCK-8 were obtained only at the doses of 1.0 μg and 2.0 μg(P＜0.05). The neuroprotective effects of CCK-8 were blocked by pretreatment with proglumide. Administration of proglumide alone could worsen the ischemia/reperfusion injury. (2) CCK-8 (1.0 μg) inhibited the increase in NO, MDA levels in the ischemic core, and also inhibited the increase in NO level in the ischemic penumbra. The rCBF in the CCK-8 group was significantly higher than the normal value at 24 h after reperfusion (P＜0.05).CONCLUSIONS:These results suggest that both endogenous and exogenous CCK-8 alleviate focal cerebral ischemia/reperfusion injury. Such an action may be associated with inhibition of free radical-induced injuries and the improvement in rCBF.     

Effects of soybean isflavones on mitochondrial damage and neuronal apoptosis induced by cerebral ischemia/reperfusion

AIM: To study the effects of soybean isoflavones on mitochondrial ultrastructure, neuronal apoptosis and expression of cytochrome C, caspase-9 and caspase-3 in the rats with cerebral ischemia/reperfusion.METHODS: Adult healthy SD rats (n=60) were randomly divided into 3 groups: sham group, ischemia/reperfusion injury (I/R) group and soybean isoflavone (SI) pretreatment group. Soybean isoflavones (120 mg·kg-1·d-1) were fed by gastric lavage for 21 d. The global ischemia/reperfusion model of the rats was established by blocking 3 vessels, and then reperfused for 1 h after 1 h of ischemia. The morphological change of the cerebral cortex cells was observed under light microscope. The mitochondrial ultrastructure of the cerebral cortex cells was determined by transmission electron microscope. The apoptotic rate of the cerebral cortex cells was detected by flow cytometry. The expression of cytochrome C, caspase-9 and caspase-3 in the cerebral cortex cells was determined by semi-quantitative RT-PCR and immunohistochemical techniques.RESULTS: Disintegration of mitochondria membrane and disappearance of the mitochondrial cristae were seen in I/R group. Compared with I/R group, the change of ultrastructure of mitochondria was significantly improved by soybean isoflavone pretreatment, and the neuronal apoptotic rate was also significantly decreased (P<0.01). The mRNA expression and protein content of cytochrome C, caspase-9 and caspase-3 in I/R group were obviously higher than those in sham group (P<0.01). Compared with I/R group, the mRNA expression and protein content of cytochrome C, caspase-9 and caspase-3 in SI group were significantly decreased (P<0.01).CONCLUSION: Soybean isoflavones attenuate cerebral ischemia/reperfusion injury by stabilizing the structure of mitochondria, preventing cytochrome C release to the cytoplasm, inhibiting the activation of caspase-9 and caspase-3 and decreasing cell apoptosis．     

Influence of high-mobility group box 1 on proliferation of neural stem cell in pre-infarction cortex of focal cerebral ischemia/reperfusion model rats

AIM：To investigate the influence of high-mobility group box 1 (HMGB1) on the proliferation of neural stem cells in peri-infarction cortex of focal cerebral ischemia/reperfusion model rats. METHODS：Male SD rats (n=48) were randomly divided into sham group, ischemia/reperfusion (I/R) group, RNA interference group and negative interference group. The rat middle cerebral artery was blocked to establish focal cerebral I/R model (ischemia for 1 h and reperfusion for 7 d). Lentivirus vector of HMGB1 shRNA was used to suppress the HMGB1 protein expression in the rat brain. The effect of RNA interference was evaluated by the methods of double-immunofluorescence labeling of HMGB1/GFAP and Western blotting. The proliferation of neural stem cells in the peri-infarction cortex was assessed by double labeling of BrdU/nestin. RESULTS：The protein expression of HMGB1 in I/R group was much higher than those in sham group (P<0.05). RNA interference effectively inhibited the HMGB1 expression (P<0.05). Double labeled BrdU/nestin positive cells in I/R group were more than that in sham group (P<0.05). The double labeled BrdU/nestin positive cells were significantly decreased in RNA interference group (P<0.05). CONCLUSION：Focal cerebral ischemia/reperfusion injury promotes the proliferation of neural stem cells in peri-infarction cortex by increasing HMGB1 protein level.     

Effects of nitric oxide synthase inhibitors on focal cerebral ischemic injury in rats

AIM:To observe the effects of nitric oxide and different isoforms of nitric oxide synthase inhibitors on the focal cerebral ischemic injury in rats. METHODS:After the rat model of focal cerebral ischemia were established with middle cerebral artery occlusion (MCAO), aminoguanidine(AG)and N^G-nitro-L-arginine(L-NA )were administrated and the cerebral infarct size, NO production,MDA content, nitric oxide synthase(NOS) and SOD activities in the focal ischemic brain tissues were examined. RESULTS:AG could significantly attenuate the focal cerebral ischemic injury, and L-NA had a protective effect when it was administrated at 1 h,6 h but not at 3 h after surgery.CONCLUSION:Cerebral ischemic injury could be attenuated by both selective and nonselective inhibition of NOS.     

Effect of Fas/FasL on late reperfusion of acute myocardial infarction and the potential oxidative stress mechanism in canine

AIM: To discuss the effect of Fas/FasL on the late reperfusion of acute myocardial infarction (AMI) and the potential oxidative stress mechanism. METHODS:Eighteen anesthetized dogs were randomly divided into three groups: late reperfusion group (n=6): ligated the coronary for 6 h, followed by reperfusion for 6 h; permanent ischemia group (n=6): after pericardium were opened for 6 h, ligated the coronary for 6 h, and did not reperfuse; control group (n=6): did not ligate the coronary but operation last for 12 h. Infarction brim myocardial Fas/FasL was detected by immunohistochemistry. Apoptosis index (AI) was detected by TUNEL. SOD and GR activity and MDA content were detected by colorimetry. RESULTS:The expression of Fas/FasL and apoptosis index were significantly higher in permanent ischemia group and late reperfusion group than those in control group (P<0.05, P<0.01), and the difference between them was also significant (P<0.05). SOD and GR activities were lower in permanent ischemia group and late reperfusion group than those in control group (P<0.05, P<0.01). The MDA contents in permanent ischemia group and late reperfusion group were higher than that in control group (P<0.05). CONCLUSION:The late reperfusion of AMI promotes the expression of Fas/FasL and myocardial apoptosis, and it may be due to oxidative stress mechanism.     

Effects of Le Er Mai on apoptosis of hippocampus neuronal cells in anaphase of cerebral ischemic reperfusion injury in rats

AIM: To investigate the effects and mechanism of Le Er Mai (LEM) on the apoptosis of hippocampus neuronal cells in the anaphase of cerebral ischemic reperfusion injury in rats.METHODS: A rat model of middle cerebral artery occlusion reperfusion (MCAO) was produced with the intraluminal filament. During reperfusion for 30 d after 2 h of ischemia, the TUNEL staining methods were used to detect apoptosis of hippocampus neuronal cells, and immunohistochemical technique were employed to examine the protein expression of Fas, Bax, caspase-3 and caspase-9 in the hippocampial. The gene expressions of fas, bax, caspase-3 and caspase-9 in hippocampial were examined by RT-PCR. RESULTS: After 2 h ischemia and 30 d reperfusion, compared with sham-operated group, TUNEL-positive staining cells and expression levels of Fas, Bax as well as caspase-3 and caspase-9 obviously increased, and the mRNA expressions of fas, bax, caspase-3 and caspase-9 in hippocampial markedly up-regulated in model group. Compared with model group, LEM at dose of 2.00 g/kg or 0.87 g/kg, and flunarizinum significantly reduced apoptosis and decreased the protein expressions of Fas, Bax, caspase-3 and caspase-9 in hippocampial, and down-regulated the mRNA expressions of fas, bax, caspase-3 and caspase-9 (P<0.05), those action of LEM in 0.87 g/kg dosage group was lower than those in 2.00 g/kg dosage group.CONCLUSION: LEM obviously lower the injury of hippocampial in the anaphase of cerebral ischemia reperfusion through inhibiting the apoptosis of hippocampus neuronal cells. The mechanism of LEM may be related to regulate the expression of signal transduction pathway correlated gene of apoptosis in neuronal cells.     

Effects of bFGF on neuronal apoptosis and fractalkine expression in cerebral ischemia/reperfusion rats

AIM: To study the effects of basic fibroblast growth factor (bFGF) on neuronal apoptosis and fractalkine expression in ischemic penumbra after cerebral ischemia/reperfusion in rats.METHODS: Thirty-six rats were randomly divided into 3 groups: sham operation group, ischemia/reperfusion group and bFGF group. The model of middle cerebral artery occlusion was established by the method of intraluminal filament blockage. The middle cerebral arteries were blocked for 1 h and then reperfused for 24 h. Neurological performances of all rats were scored with Bederson's standard. The brain tissues of the rats were stained and the average infarct volume was calculated. TUNEL method was used to determine the number of apoptotic neurons, and the expression of fractalkine was detected by the method of immunohistochemistry.RESULTS: The score of neurological performances in bFGF group was 2.23±0.59, lower than that in ischemia/reperfusion group (3.18±0.65). The number of apoptotic neurons in bFGF group (13.22±1.35) was lower than that in ischemia/reperfusion group (17.28±1.01, P<0.05), which was the lowest in sham operation group (0.91±0.65). Compared with sham operation group, the expression of fractalkine in ischemia/reperfusion group was decreased. The expression of fractalkine in bFGF group was mainly higher than that in ischemia/reperfusion group (P<0.05).CONCLUSION: Up-regulation of fractalkine may be one of the molecular mechanisms of bFGF to protect neurons against ischemia/reperfusion injury.     

Effect of Ginkgo biloba extract on the expression of c-fos and HSP70 following focal cerebral ischemic reperfusion in rats

AIM: To investigate the influence of Ginkgo biloba extract (GBE) on the expression of c-fos, heat shock protein 70 (HSP70) during focal cerebral ischemic reperfusion in rats. METHODS: The middle cerebral artery occlusion (MCAO) model described by Zea longa was used. Healthy Wistar rats were randomized to 4 groups. Immunohistochemistry, in situ hybridization and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) were used to detect the expression of c-fos gene, HSP70 and cell apoptosis at different reperfusion time points: 1, 6, 12, 24 hours and 3, 7 days after recirculation. RESULTS: The positive reactions of both c-fos and HSP70 were significantly increased at different reperfusion time in GBE-pretreated ischemia/reperfusion (IR) group than those in ischemia/reperfusion group (P<0.01) and the number of TUNEL-positive cells was reduced in GBE-pretreated IR group. CONCLUSION: The GBE induced the expression of c-fos, HSP70 and contributes to neuroprotective activities after cerebral ischemia.     

Relationship between morphologic changes in neuron or neuroglial cells and expression of TNF-α and c-Myc in cortex after focal cerebral ischemia/reperfusion in MCAO rats

AIM: To investigate the relationship between morphologic changes in neuron or neuroglial cells and expression of tumor necrosis factor α (TNF-α) and c-Myc in cortex after focal cerebral ischemia/reperfusion in MCAO rats. METHODS: The focal cerebral ischemia/reperfusion model was established by intraluminal thread occlusion of the middle cerebral artery (MCAO). The middle cerebral arteries of rats were occluded for 2 hours and reperfused for 1, 3 and 7 days. Using the techniques of immunohistochemical staining and optical microscopy, the morphologic changes in neuron or neuroglial cells were observed in the cortex of frontal or parietal lobe; the cell types which dynamicaly expressed TNF-α, c-Myc in the different period were also observed. RESULTS: The degeneration or necrosis of neuron or neuroglial cells were observed at the center of infarction, it was very serious at 3 d after reperfussion. Astrocyte and microglial cell proliferation were observed at the broder of infarction. TNF-α and c-Myc positive cells, most of which were astrocytes and microglial cells, increased significantly at 3 d after reperfusion. CONCLUSION: TNF-αand c-Myc may play an important role in the regulation of neuron or neuroglial cells after focal cerebral ischemia with reperfusion.     

Inhibitory effect of ischemic postconditioning on autophagy induced by focal cerebral ischemia reperfusion in rats

AIM: To investigate the effect of ischemic postconditioning (IPC) on autophagy induced by focal cerebral ischemia reperfusion (I/R) in rats. METHODS: Healthy male SD rats were assigned randomly into sham-operation (sham) group, I/R group and IPC group with 10 rats in each group. The rats in sham group were only exposed the right common, internal and external carotid artery surgically. The rats in I/R group were subjected to right middle cerebral artery occlusion (MCAO) by the modified Longa suture method for 2 h followed by 24 h of reperfusion. The rats in IPC group were subjected to MCAO for 2 h followed by reperfusion of the ipsilateral common carotid artery occlusion for 10 s for 5 episodes, and then reperfusion for 24 h. Autophagy was obeserved by transmission electron microscopy (TEM). The protein levels of mammalian target of rapamycin (mTOR), p-mTOR and microtubule associated protein light chain 3 (LC3)-II in brain tissue of the rats were determined by Western blot. Pathological changes of brain tissue were observed by HE staining. RESULTS: The protein levels of mTOR and p-mTOR in IPC group were significantly higher than those in I/R group (P<0.05). The expression of LC3-II in IPC group was significantly lower than that in I/R group (P<0.01). The cerebral infarction area and brain water content in IPC group were significantly lower than those in I/R group (P<0.01). HE staining showed that neurons degeneration and necrosis in IPC group were significantly alleviated compared with I/R group. TEM observation showed that IPC revealed fewer autophagosomes, with much less severe cell damage than that in I/R group. CONCLUSION: IPC reduces brain ischemia reperfusion damage by decreasing autophagy of brain cells, which might be related to the activation of mTOR.     

Glutamate transport across blood brain barrier after transient global ischemia/reperfusion in rats

AIM: to study the change of glutamate(Glu) transport across blood brain barrier(BBB) in rat following forebrain ischemia/reperfusion. METHODS: BBB unidirectional transfer constant(K_i) for [³H]-Glu in rat hippocampus, cerebral cortex and striatum were determined after rats were subjected to cerebral ischemia 10 min (two-carotid occlusion plus hypovolemic hypotension) followed by 0.17, 2, 6 and 24 h of reperfusion. The recovery of [³H]-Glu in cerebrum was also determined after intracerebral injection of [³H]-Glu in another experiment. RESULTS: Compared with control rat brain, K_i for [³H]-Glu significantly(P＜0.05) decreased at 10 min cerebral ischemia followed by 0.17, 2 and 6 h of reperfusion. At 5 min after intracerebrally injecting [³H]-Glu, recovery of [³H]-Glu in control rat brain was 23.83%. The result indicted that there is a Glu efflux mechanism on BBB. This efflux was not significantly inhibited by pretreatment of 200 mg/L probenecid. After 10 min cerebral ischemia followed by 2 h of reperfusion, the recovery(13.13%) was significantly lower than contro(P＜0.05), its recovery was only 55% of the control. The result indicated that cerebral ischemia/reperfusion may enhanced the efflux of [³H]-Glu from brain. CONCLUSION: Cerebral ischemia/reperfusion significantly reduced Glu BBB transport from plasma to brain and enhanced efflux of Glu from brain.