Focal Ischemia-reperfusion Injury Research Articles

Effect of celastrol postconditioning on focal cerebral ischemia-reperfusion injury in rats

Objective To evaluate the effect of celastrol postconditioning on focal cerebral ischemiareperfusion (I/R) injury in rats.Methods Sixty-four Sprague-Dawle rats (32 males,32 females),weighing 250300 g,were randomized into 4 groups using a random number table (n =16 each):sham operation group (group S) ; celastrol control group (group S + C) ; focal cerebral I/R group (group I/R) ; celastrol postconditioning group (group I/R + C).Focal cerebral I/R were produced by middle cerebral artery occlusion (MCAO).Dimethyl sulfoxide (DMSO) 0.3 ml/kg was injected intraperitoneally after shame operation in group S.Celastrol 3 mg/kg was injected intraperitoneally after shame operation in group S + C.DMSO 0.3 ml/kg was injected intraperitoneally at 5 min of reperfusion in group I/R.Celastrol 3 mg/kg was injected intraperitoneally at 5 min of reperfusion in group I/R + C.The neurologic deficit was scored at 5 min before reperfusion and 24 h of reperfusion.The infarct size was detected by TTC staining,and then the percentage of infarct size was calculated.The pathological changes in CA1 region of ischemic hippocampus were detected by HE staining.The activity of nicotinamide adenine dinucleotide phosphate oxidase (NOX),content of reactive oxygen species (ROS) and expression of NOX1 and NOX2 mRNA (by RT-PCR) in ischemic brain tissues were detected.Results Compared with S and S + C groups,the neurologic deficit scores,infarct size,percentage of infarct size,NOX activity and ROS content were significantly increased,and the expression of NOX1 mRNA and NOX2 mRNA was up-regulated in I/R and I/R + C groups (P ＜ 0.01).Compared with group I/R,the neurologic deficit scores,infarct size,percentage of infarct size,NOX activity and ROS content were significantly decreased,and the expression of NOX1 mRNA and NOX2 mRNA was down-regulated in group I/R+ C (P ＜ 0.01).There was no significant difference in the parameters mentioned above between group S and group S + C (P ＞ 0.05).The pathological changes in CAl region of ischemic hippocampus were significantly attenuated in group I/R + C (P ＜ 0.01).Conclusion Postconditioning with celastrol can auenuate focal cerebral [/R injury in rats and inhibiton of oxidative stress response in brain tissues may be involved in the mechanism. Key words: Tripterygium; Brain; Reperfusion injury; NADPH oxidase; Reactive oxygen species; Ischemic postconditioning

Neutroprotective efficacy of sodium tanshinone B on hippocampus neuron in a rat model of focal cerebral ischemia

To investigate the protective effects of sodium tanshinone B (STB) on brain damage following focal ischemia-reperfusion (I/R) injury through interfering with N-methyl-D-aspartic acid receptor (NMDAR) and excitatory and inhibitory amino acids, and evaluate the potential mechanisms of the neuroprotective activity of STB. Transient forebrain ischemia was induced by middle cerebral artery occlusion (MCAO). The rats were randomized into a sham operated group, a model group (I/R) and three STB different dose groups. Rats were pretreated with STB at the doses of 4, 8, 16 mg/kg (STB(1), STB(2), STB(3)) for 3 days before MCAO. The expression of NMDAR1 was detected by immunohistochemistry and Western blotting. The concentrations of glutamate and γ-aminobutyric acid (GABA) were analyzed using high performance liquid chromatography. STB treatment reduced neurological defect scores, cerebral infarction volume and brain water content. The levels of NMDAR1 were significantly higher in the l/R and STB(1) groups than that of the sham and the STB(3) groups (P<0.01). Optical density of NMDAR1 was significantly increased in cornu ammonis (CA)1 region of the l/R group (P<0.05). STB treatment reduced NMDAR1 optical density in the CA1 region (P<0.01). The levels of glutamate were significantly lower in the hippocampus in the STB(3) group than that of the l/R, STB(1) and STB(2) groups (P<0.01). Preconditioning with STB appears to be a simple and promising strategy to reduce or even prevent cerebral l/R injury and has potential for future clinical application.

Effects of NSC23766 on focal cerebral ischemia-reperfusion injury in diabetic rats

Objective To investigate the effects of NSC23766 on focal cerebral ischemia-reperfusion (I/R) injury in diabetic rats.Methods Fifty-one male Sprague-Dawley rats,aged 2-3 months,weighing 250-300 g,in which diabetes mellitus was successfully induced by intraperitoneal streptozotocin 60 mg/kg,were randomly assigned into 3 groups (n=17 each): sham operation group (group S),focal cerebral I/R group (group I/R) and specific Racl inhibitor NSC23766 group (group N).Focal cerebral I/R was induced by middle cerebral arterial occlusion in groups I/R and N.In group N,NSC23766 (50 μg) was injected into the cerebral lateral ventricle at 15 min before ischemia,while the equal volume of normal saline was injected in groups S and I/R.Neurological deficits were scored at 24 h of reperfusion.The rats were then sacrificed and the brains were removed for determination of infarct volume (by TTC staining),apoptosis (by TUNEL) and phosphorylation of p38MAPK (by Western blot)and for microscopic examination (by HE and Nissl staining).Apoptotic index was calculated.Results Compared with group S,the neurological deficit scores aud apoptotic index were significantly increased,the infarct volume was enlarged,and the phosphorylation of p38MAPK was significantly increased in groups I/R and N (P ＜ 0.05).The neurological deficit scores and apoptotic index were significantly lower,and the infarct volume was significantly smaller,and the phosphorylation of p38MAPK was significantly lower in group N than in group I/R (P ＜ 0.05).Conclusion NSC23766 can reduce focal cerebral I/R injury in diabetic rats. Key words: racl GTP-binding protein; Diabetes mellitus; Reperfusion injury; Brain

Mechanisms of Periodic Acceleration Induced Endothelial Nitric Oxide Synthase (eNOS) Expression and Upregulation Using an In Vitro Human Aortic Endothelial Cell Model

Following severe injury in cases like ischemia reperfusion, recovery and tissue repair are compromised due to microvascular failure. Nitric oxide (NO) has been shown to have both vasodilatory and anti-inflammatory effects, and to enhance recovery and tissue repair by increasing microcirculation. Therefore, techniques that induce endothelial derived nitric oxide (eNO) may provide a suitable supplemental treatment following injury. Periodic acceleration (pGz) applied to the supine positioned body in a repetitive head-foot direction increases pulsatile shear stress to the vascular endothelium. pGz provides cytoprotection in part because it increases expression of eNOS and eNOS phosphorylation (p-eNOS) in the heart and vasculature in models of whole body and focal ischemia reperfusion injuries in vivo. To confirm that endothelial cells are indeed the central mediator of NO production and to understand the signal transduction pathway through which pGz upregulates eNOS, we used an in vitro model of human aortic endothelial cells coated tubing, mimicking realistic conditions of blood vessels in vivo that are exposed to linear pulsatile flow (PF) or PF plus pGz (PF + pGz). PF + pGz produced significantly higher values of total eNOS and p-eNOS content than PF alone. Periodic acceleration also increased the ratio of phosphorylated Akt (p-Akt) to total Akt, as well as the ratio of p-ERK1/2 to total ERK1/2. Further, Wortmannin (PI3K inhibitor) inhibited phosphorylation of Akt and eNOS but not eNOS upregulation, while PD98059 (MEK inhibitor) inhibited phosphorylation of ERK1/2 and eNOS upregulation, but not eNOS phosphorylation. Therefore, this investigation shows that, pGz increases eNO and p-eNOS through the PI3K–Akt pathway and upregulated eNOS expression through the MEK-ERK1/2 pathway in cultured endothelial cells.

Effect of dexmedetomidine pretreatment on focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of dexmedetomidine pretreatment on focal cerebral ischemia-reperfusion(I/R) injury in rats.Methods One hundred male SD rats weighing 290-310 g were randomly divided into 5 groups(n =20 each):sham operation group(group SH) ; focal cerebral I/R group; focal cerebral I/R + dexmedetomidine 100 μg/kg(group L); focal cerebral I/R+ dexmedetomidine 200 μg/kg (group M) and focal cerebral I/R + dexmedetomidine 400 μg/kg(group H).Focal cerebral I/R was produced by occlusion of middle cerebral artery for 60 min followed by 24 h of reperfusion.Dexmedetomidine 100,200 and 400 μg/kg were injected intraperitoneally 15 min before ischemia in groups L,M and H respectively.While equal volume of normal saline was injected intraperitoneally in group SH.Neurologic function was assessed and scored at 24 h of reperfusion.Then the animals were sacrificed and brains were removed for determination of cerebral infarct volume and microscopic examination.The expression of heat shock protein 70(HSP70) and activity of Na+ -K + -ATPase in ischemic cortex and activity of SOD and concentration of cortisol in plasma were determinationed at 24 h of reperfusion.Results Compared with group SH,neurologic deficit scores and plasma concentration of cortisol were significantly increased,activities of SOD and Na+ -K+ -ATPase decreased and expression of HSP70 was up-regulated in groups I/R,L,M and H( P ＜ 0.05).Compared with group I/R,neurologic deficit scores and plasma concentration of cortisol were significantly decreased,activities of SOD and Na+ -K+ -ATPase increased and expression of HSP70 was up-regulated in a dose-dependent manner ( P ＜ 0.05),and the pathological change was reduced in a dose-dependent manner in groups L,M and H.Conclusion Dexmedetomidine pretreatment can attenuate focal cerebral I/R injury in a dose-dependent manner through improvement of brain cell energy metabolism and reduction of lipid peroxidation and stress reaction. Key words: Dexmedetomidine; Brain; Reperfusion injury

Effect of emulsified isoflurane preconditioning on postsynaptic density protein 95 activation in brain during focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of emulsified isoflurane preconditioning on postsynaptic density protein 95 (PSD95) activation in brain during focal cerebral ischemia-reperfusion (I/R)injury in rats.Methods Thirty-two pathogen-free male SD rats weighing 280-300 g were randomly divided into 4 groups (n =8each): sham operation group(group S),group I/R,emulsified isoflurane group(group EI) and lipid emulsion group(group LE).Focal cerebral I/R was induced by middle cerebral artery occlusion for 2 h followed by reperfusion.8％ emulsified isoflurane 10.5 ml/mg or 30％ lipid emulsion 10.5 ml/mg was injected intraperitoneally at 24h before I/R in groups EI and LE respectively.The neurologic deficit score (NDS) was evaluated at 6 h of reperfusion and then 4 rats were sacrificed,and brains were removed for determination of phosphorylatied PSD95 (pPSD95) expression in ischemia cortex and hippocampus by Western blot.Four rats were sacrificed at 24 h of reperfusion and then their brains were removed for determination of infarct volume percentage.Results NDS,infarct volume percentage and pPSD95 expression in ischemia cortex and hippocampus were higher in groups I/R,EI and LE than in group S( P ＜ 0.01 ).NDS,infarct volume percentage and pPSD95 expression in ischemia cortex and hippocampus were lower in group EI than in group I/R( P ＜ 0.05).There was no significant difference in NDS,infarct volume percentage and pPSD95 expression between groups I/R and LE(P ＞ 0.05).Conclusion Emulsified isoflurane preconditioning can attenuate focal cerebral I/R injury in rats by inhibiting PSD95 activation in brain. Key words: Isoflurane ; Fat emulsions, intravenous ; Membrane proteins; Reperfusion injury ; Brain; Ischemic preconditioning

Effects of intrathecal Ro25-6981 on focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of intrathecal (IT) Ro25-6981 (a selective NR2B receptor antagonist) on focal cerebral ischemia-reperfusion (I/R) injury in rats.Methods Sixty healthy male SD rats weighing 280-320 g in which IT catheter was successfully implanted without complication were randomly divided into 4 groups ( n ＝ 15 each):group sham operation (group S) ; group focal cerebral I/R(group I/R) ; group I/R + Ro25-6981 (group Ro) and group I/R+ normal saline (group NS).The right middle cerebral artery was occluded for 2 h with a nylon thread with rounded tip which was inserted into right internal carotid artery and advanced cranially until resistance was met in groups I/R,Ro and NS.In group Ro Ro25-6981 100 μg/10 μl was injected IT at 0,2,23 h of reperfusion,while in group NS NS was injected IT instead of Ro25-6981.Neurological dificit was assessed and scored (0 ＝ no deficit,3 ＝ severe deficit) at 24 h of reperfusion.The infarct size was determined by 2,3,5-triphenyl tetrazolium chloride staining.Results IT administration of Ro25-6981 significantly reduced cerebral I/R-induced infarct sized and neurological deficit score in group Ro as compared with groups I/R and NS.Conclusion Ro25-6981 injected IT can protect the brain against local cerebral I/R injury. Key words: Receptors,N-methyl-D-aspartate ; Injections,spinal; Reperfusion injury; Brain

Effect of emulsified isoflurane preconditioning on neuronal apoptosis in hippocampal CA1 region induced by focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of preconditioning with emulsified isoflurane (eISO) on neuronal apoptosis in hippocampal CA1 region induced by focal cerebral ischemia-reperfusion (I/R) injury in rats. Methods Forty-eight healthy adult male SD rats weighing 250-300 g were randomly divided into 6 groups (n = 8 each): sham operation group (group S); I/R group; eISO + I/R group (group EI); LY294002 (a specific PI3K inhibitor) + eISO + I/R group (group L+ EI); LY294002 + I/R group (group L) and DMSO (solvent for LY294002) + I/R group (group DMSO). Focal cerebral I/R was induced by 2 h middle cerebral artery occlusion ( MCAO). A nylon thread (0.26 mm in diameter) with rounded tip was inserted into internal carotid artery and advanced cranially until resistance was met (depth of insertion about 18-20 mm) . eISO 10.5 ml/kg (120 mg/ml) was injected intraperitoneally (IP) in groups EI and L+ EI. LY294002 (25 mmol/L) 5 pi was injected into cerebral ventricle on the ischemic side in group L + EI ( at 30 min before eISO) and group L. DMSO 5 μl was injected into the cerebral ventricle on ischemic side before MCAO in group DMSO. Neurologic deficit was assessed and scored (0 = normal, 4 = unconscious) at 24 h of reperfusion. The animals were then killed and their brains were removed for detection of neuronal apoptosis (by TUNEL) and p-Akt expression (by immuno-histochemistry) in hippocampal CA1 region. Results Cerebral I/R significantly increased the neurologic deficit scores, the number of apoptotic cells and p-Akt expression in group I/R as compared with group S. Preconditioning with elSO attenuated the I/R-induced increase in neurologic deficit scores and number of apoptotic cells but further increased p-Akt expression. The neuroprotective effect of eISO preconditioning against I/R-induced changes was counteracted by LY294002. Conclusion eISO preconditioning can attenuate focal cerebral I/R-induced neuronal apoptosis in rats by activating PI3K/Akt pathway. Key words: Isoflurane; Fat emulsions, intravenous; Ischemic preconditioning; Brain; Reperfusion injury; Apoptosis

Effect of sevoflurane preconditioning on CHOP expression in cerebral cortex after focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of sevoflurane preconditioning on CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP) expression in the cerebral cortex after focal cerebral ischemiareperfusion (I/R) injury in rats and the mechanism. Methods Thirty-six male SD rats weighing 250-280 g were randomly divided into 3 groups ( n = 12 each) : sham operation group (group S) , focal cerebral I/R group (group I/R) and sevoflurane preconditioning group (group Sevo-pc). The animals were anesthetized with intraperitoneal chloral hydrate 300 mg/kg. In groups I/R and Sevo-pc, focal cerebral ischemia was induced by middle cerebral artery occlusion using a nylon thread with rounded tip inserted into the right internal carotid artery and advanced cranially until resistance was met. The occlusion was maintained for 1 h followed by 24 h reperfusion. Group Sevo-pc inhaled 2.7% sevoflurane for 1 h before ischemia. Neurological deficits were assessed and scored at the end of 24 h reperfusion and then the rats were decapitated. Their brains were immediately removed. The cerebral infarct size was determined by TTC staining. The CHOP expression in the ischemic cerebral cortex was determined by immunohistochemistry. The number of apoptotic neurons was counted using TUNEL. Results The neurological deficit scores were significantly higher, the cerebral infarct size was significantly larger, and the CHOP expression and the number of apoptotic neurons were significantly higher in groups I/R and Sevo-pc than in group S ( P ＜ 0.01) . The neurological deficit scores were significantly lower, the cerebral infarct size was significantly smaller, and the CHOP expression and the number of apoptosis neurons were significantly lower in group Sevo-pc than in group I/R ( P ＜ 0.05 or 0.01) . Conclusion Sevoflurane preconditioning may protect the brain against focal cerebral I/R injury by down-regulating CHOP expression in the cerebral cortex in rats. Key words: Anesthetics, inhalation; Ischemic preconditioning; Reperiusion injury; Cerebral cortex; Transcription factor CHOP

The effect of heliox treatment in a rat model of focal transient cerebral ischemia

Manipulation of inhaled gases during ischemia/reperfusion is a potential novel therapy for acute stroke. We previously found that treatment with a mixture of 70%/30% helium/oxygen (heliox) or 100% oxygen protects the brain against acute focal ischemia–reperfusion injury. This study evaluates the potential neuro-protective effects of delayed heliox treatment and its dose response effects in a rat transient focal cerebral ischemia model. Adult male rats were subjected to 2-h middle cerebral artery occlusion and then assigned to 1 of 4 inhaled gas exposure groups: I: 70%/30% nitrogen/oxygen (control); II: 70%/30% helium/oxygen administered immediately after occlusion; III: 70%/30% helium/oxygen administered after a 30–60min delay; or, IV: 40%/30%/30% nitrogen/helium/oxygen administered immediately after occlusion. Outcome measurements included infarct size and neurological deficit score. Mean infarct sizes from groups I to IV were 228, 35, 109, and 124mm3 respectively (p=0.012). Only group II had significantly smaller infarct size compared to the control group (p=0.008). In addition, only Group II had a significantly lower neurological deficit score at 24h post ischemia when compared to the control group (p<0.001). Since heliox reduced infarct size and improved neurological deficit scores if initiated immediately after onset of ischemia, it may be a useful adjuvant to other stroke therapies.

Protective effect of etomidate postcoditioning on cerebral ischemia- reperfusion injury in rats

Objective To observe the protective effect of etomidate postcoditioning on transient focal cerebral ischemiareperfusion (I/R) injury in rats. Methods Thirty-two male Sprague-Dawley rats (six months, body weight between 250 g～300 g)were randomly divided into four groups (n=8): Sham group,I/R group, L group (lipid), Eto group (etomidate). Ischemia were induced by occluding the right middle cerebral artery in rat for 2 h. In I/R group, L group and Eto group, saline, lipid (the vehicle solution of etomidate )or etomidate(20 mg/kg)( the volume was fixed to 1 ml/100 g )were administered intraperitoneally immediately to rats at the onset of reperfusion respecetively. The neurological outcomes were evaluated after reperfusion 12,24 and 72 h by modified neurologic severity scores (NSS). The infarct size of brain was then assessed by 10 g/L 2,3,5-triphenyltetrazolium (TTC) staining following the last neurological outcome evaluation. Results The neurologic severity scores in Sham group was 0 at the three time points, and the neurologic severity scores in I/R group and L group at reperfusion 12,24 and 72 h were significantly more than those in Sham group (0)and Eto group (P＜0.05), there was no significant difference between I/R group and L group (P＞0.05 on 12, 24,72 h ). The infarct size of brain in I/R group(40.1±2.3 )% and L group (39.3±2.1)% were evidently greater than that in Sham group (0) and in Eto group (26.0±4.9)% (P＜0.05) at reperfusion 72 h, and there was no significant difference between I/R group and L group( P＞0.05 ). Conclusion Etomidate( 20 mg/kg ) has a brain protective effect on cerebral inschemia-reperfusion injury in rats. Key words: Etomidate; Postcoditioning; Cerebral ischemia-reperfusion; 2,3,5-triphenyltetrazolium

Effect of 8% emulsified isoflurane postconditioning on focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of postconditioning with 8 % emulsified isoflurane (EI) on focal cerebral ischemia-reperfusion (I/R) injury in rats. Methods Forty-eight male SD rats weighing 260-300 g were randomly divided into 6 groups ( n = 8 each): group Ⅰ sham operation (group S); group Ⅱ I/R; group Ⅲ,Ⅳ, Ⅴ 3 different doses of EI (group L-EI, M-EI, H-.EI) and group Ⅵ lipid emulsion (group LE). Right middle cerebral artery occlusion (MCAO) was induced by inserting a nylon thread 0.24 mm in diameter into right internal carotid artery. The thread was threaded cranially until resistance was met. MCAO was maintained for 2 h followed by 24 h reperfusion in group Ⅱ-Ⅵ. In group Ⅲ-Ⅴ EI 3.5, 7.0 and 10.5 ml/kg were injected intraperitoneally (IP) immediately before reperfusion respectively. In group LE 30% lipid emulsion 10.5 ml/kg was given instead of EI. The neurologic deficit was assessed and scored (0 = normal, 4 = unable to move and unconscious). The animals were then killed and infarct size was measured. Results IP 8% emulsified isoflurane 7.0 and 10.5 ml/kg injected before reperfusion significantly reduced neurologic deficit scores and infarct size in group M-EI and H-EI as compared with group I/R. Conclusion Postconditioning with 8% emulsified isoflurane can protect the brain against focal cerebral I/R injury. Key words: Isoflurane; Lipid emulsions, intravenous; Reperfusion injury; Brain; Ischemic postconditioning

Effect of parecoxib pretreatment on focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of parecoxib pretreatment on focal cerebral ischemia-reperfusion (I/R) injury in rats. Methods Sixty-four male SD rats weighing 250-300 g were randomly divided into 4 groups ( n= 16 each): sham operation group (group S); focal cerebral I/R group; focal cerebral I/R + parecoxib 5 mg/kg group (group P5); focal cerebral I/R + parecoxib 10 mg/kg group (group P10). Focal cerebral I/R was produced by occlusion of middle cerebral artery for 2 h followed by 24 h of reperfusion. Parecoxib 5 and 10 mg/kg were injected intravenously through the internal jugular vein 30 min before ischemia in group P5 and P10 respectively. The neurologic deficit scores (NDSs) were measured at 24 h of reperfusion and then the rats were decapitated.Brains were rapidly removed for determination of the infarct volume, apoptosis rate and expression of Bcl-2 and Bax. The ratio of Bcl-2 to Bax (Bcl-2/Bax) was calculated. Results The NDSs, apoptosis rate and expression of Bcl-2 and Bax were significantly higher, Bcl-2/Bax was significantly lower, and the infarct volume was significantly larger in group I/R than in group S ( P ＜ 0.01 ). The NDSs were significantly lower in group P10, and the apoptosis rate and Bax expression were significantly lower, the infarct volume was significantly smaller, Bcl-2 expression and Bcl-2/Bax were significantly higher in group P5 and P10 than in group I/R (P ＜0.05 or 0.01). The infarct volume was significantly smaller, the apoptosis rate and Bax expression were significantly lower, and Bcl-2 expression and Bcl-2/Bax were significantly higher in group P10 than in group P5 ( P ＜ 0.05 or 0.01 ). Conclusion Pretreatment with parecoxib can attenuate focal cerebral I/R injury in a dose-dependent manner through inhibition of cell apoptosis via up-regulation of Bcl-2 expression and down-regulation of Bax expression in rats. Key words: Cyclooxygenase 2 inhibitors; Brain; Reperfusion injury

Role of PI3K/Akt signal pathway in sevoflurane postconditioning against focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the role of PI3KIAkt signal pathway in sevoflurane postconditioning against focal cerebral ischemia-reperfusion （I/R） injury. Methods Sixty-four adult male SD rats weighing 300- 350 g were randomly assigned into 4 groups （ n = 16 each） ： group I focal cerebral I/R （group I/R） ; group II sevoflurane postconditioning （group SP） ; group III sevoflurane postconditioning ＋ wortmannin （group SP ＋ W） and group IV I/R ＋ wortmannin （group I/R ＋ W） . The animals were anesthetized with intraperitoneal 10% chloral hydrate 300-350 mg/kg, traeheostomized and mechanically ventilated. ECG was continuously monitored. Right femoral artery was cannulated for BP monitoring. Focal cerebral I/R was induced by electro-coagulation of left middle cerebral artery and 60 min occlusion of bilateral common carotid arteries followed by reperfusion. The animals inhaled 2.5% sevoflurane in 02 for 60 min as soon as reperfusion was started in group II and III . Wortmannin 0.6 mg/kg was administered iv at 30 rain before reperfusion in group III and/ IN. Neurological function was assessed and scored at 24, 48 and 72 h （T1-3 ） of reperfusion. The animals were decapitated after the last neurological function assessment. Their brains were immediately removed for determination of infarct size. The expression of phosphorylated Akt and Bad （p-Akt, p-Bad） were determined by Western-blot analysis in isehemic penumbra. Results Sevoflurane postconditioning significantly improved the neurological function, decreased the infarct size and increased the expression of p-Akt and p-Bad in group II as compared with group I . There was no significant difference in all variables between group I and group IV . Wortmannin attenuated the protective effect of sevoflurane postcoditioning against focal cerebral I/R injury. Conclusion Up-regulation of p-Bad expression induced by activation of PI3K/Akt signal pathway is involved in the protective effect of sevoflurane postconditioning against focal cerebral I/R injury. Key words: Anesthetics, inhalation ; Brain ischemia ; Reperfusion injury ; Postconditioning

Effect of emulsified isoflurane preconditioning on focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of emulsified isoflurane preconditioning on focal cerebral ischemia-reperfusion (I/R) injury in rats and the mechanism. Methods Fifty-six healthy male adult SD rats weighing 250-280 g were randomly divided into 4 groups (n = 14): group Ⅰ sham operation (group S); group Ⅱfocal cerebral I/R; group Ⅲ emulsified isoflurane preconditioning and group Ⅳ fat emulsion preconditioning. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) using a nylon thread with rounded tip inserted into internal carotid artery and advanced cranially until resistance was met. MCAO was maintained for 2 h followed by 24 h reperfusion. In group Ⅲ and Ⅳ 8% emulsified isoflurane 7.5 ml/kg and 3% fat emulsion 7.5 ml/kg were injected intraperitoneally at 24 h before MCAO respectively. Neurologic outcome was evaluated at 24 h of reperfusion and scored (0 = no deficit, 4 = unable to crawl, loss of consciousness). The animals were then killed and brains removed. The infarct size was assessed. The apoptotic cells were detected by TUNEL and calculated. The expression of Bax, Bcl-2, cytochrome C and caspase-3 protein was detected by immunohistochemical staining. Results The neurologic deficit scores were significantly lower in emulsified isoflurane preconditioning group than in I/R group. Preconditioning with emulsified isoflurane significantly decreased the infarct size and the number of apoptotic cells and increased the expression of Bcl-2 protein and inhibited the expression of Bax, cytochrome C and caspace-3 protein. Conclusion Emulsified iscflurane preconditioning can protect the brain from focal cerebral I/R by increasing Bcl-2 protein expression and decreasing Bax protein expression, and reducing cytochrome C release from mitochondria, caspase-3 activation and neuronal apoptosis. Key words: Isoflurane; Fat emulsions, intravenous; Ischemic preconditioning; Reperfusion injury; Brain

Effect of sevoflurane preconditioning on mitocbondrial permeability transition pore following focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effect of sevoflurane preconditioning on mitochondrial permeability transition pore (mPTP) following focal cerebral ischemia-reperfusion (I/R) injury. Methods Male adult SD rats weighing 250-280 g were randomly assigned into 5 groups ( n = 12 each): group Ⅰ sham operation(group S); group Ⅱ focal cerebral ischemia-reperfusion (group I/R); group Ⅲ sevoflurane preconditioning + I/R(group Sev); group Ⅳ 5-HD + Sev + I/R and group Ⅴ 5-HD + I/R. Focal cerebral I/R was induced by right middle cerebral artery occlusion (MCAO). A 50 mm long 4.0 nylon thread was inserted into right internal carotid artery and advanced cephalad until resistance was met. MCAO was maintained for 2 h followed by 24 h reperfusion in group Ⅱ-Ⅴ. In group Ⅲ the animals inhaled 2.4% sevoflurane for 60 min at 24 h before I/R. In group Ⅳ 5-HD 40 mg/kg was injected intraperitoneally at 30 min before sevoflurane preconditioning. In group Ⅴ 5-HD 40 mg/kg was injected IP at 30 min before MCAO. The animals were decapitated at 24 h of reperfusion. The parietal cortex of the ischemic side was isolated. Spectrophotometry was used to measure the mPTP activity. The expression of Bcl-2 and Bax protein (by Western blotting) and neuronal apoptosis (by TUNEL) were determined.Results Sevoflurane preconditioning significantly inhibited the activity of mPTP, reduced neuronal apoptosis induced by I/R and increased Bcl-2 protein expression but had no significant effect on Bax protein expression. The protective effects of sevoflurane preconditioning against cerebral I/R were blocked by 5-HD. Conclusion Sevoflurane could inhibit the mitochondrial permeability transition and reduce neuronal apoptosis via activation of mito-KATP channel and up-regulation of Bcl-2 expression. Key words: Mitochondrial membrane transport proteins; Anesthetics, inhalation; Reperfusion injury; Brain; Apoptosis

Effects of combination of ischemic postconditioning and remote ischemic postconditioning on focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effects of combination of ischemic postconditioning (IPC) and remote IPC on the focal cerebral ischemia-reperfusion (I/R) injury in rats. Methods Eighty-six adult male SD rats were randomly divided into 5 groups: sham operation group (group Ⅰ, n = 19) , I/R group (group Ⅱ, n=19) , IPC group (group Ⅳ, n = 16) , remote>IPC group (group Ⅳ, n = 16), and IPC + remote IPC group (group V , n = 16) . Focal cerebral I/R was produced by occlusion of the right middle cerebral artery (MCA) for 1.5 h followed by 24 h of reperfusion. In group Ⅰ, operation was performed but focal cerebral I/R was not produced. In group Ⅲ , the rats were subjected to 3 episodes of 30 s ischemia at 30 s intervals before 24 h of reperfusion. In group Ⅳ, after 1.5 h of the right MCA occlusion, remote IPC was performed by occluding the right femoral artery for 5 min before 24 h of reperfusion. In group Ⅴ, IPC and remote IPC were performed as described in group Ⅲ and Ⅳ respectively before 24 h of reperfusion. The neurologic deficit scores (NDSs) were measured at 2 and 24 h of reperfusion. Ten rats in each group were decapitated at 24 h of reperfusion and brains rapidly . removed for measuring the cerebral infarct size (IS). The expression of microtubule-associated protein 2 (MAP2) were detected. The animals received iv injection of fluorescein isothiocyanate (FICT)-dextran via the femoral vein 1 min before decapitation, for laser confocal scanning. The contralateral side was served as control. Results As compared with group Ⅰ, the NDSs and cerebral IS on the ischemic side were significantly increased, and the cerebral expression of MAP2, plasma volume of the cerebral tissues, and diameter and length of the cerebral microvessel on the ischemic side significantly decreased in group Ⅱ, Ⅲ , Ⅳ and Ⅴ ( P < 0.05 ) . As compared with group Ⅱ, the NDSs and cerebral IS on the ischemic side were significantly decreased, and the cerebral expression of MAP2, plasma volume of the cerebral tissues, and diameter and length of the cerebral microvessel on the ischemic side significantly increased in group ID , Ⅳ and Ⅴ( P < 0.05). Conclusion Although the combination of IPC and remote IPC can attenuate the focal cerebral I/R injury in rats, the efficacy is similar to that of either of them alone. Key words: Reperfusion injury; Brain; Ischemia postconditioning

Effects of brain-derived neurotrophic factor pretreatment on oxidative stress and neuron apoptosis following focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the effects of different dose of brain-derived neurotrophic factor (BDNF) pretreatment on oxidative stress and neuron apoptosis following focal cerebral ischemia-reperfusion injuries in rats. Methods Focal cerebral ischemia-reperfusion model was established in rats by reversible left middle cerebral artery occlusion with filament. Left cerebral ischemia was for 2 hours and then with 72 hours reperfusion. BDNF was injected into the lateral ventricle before ischemia for 12 hours. The activities of brain tissue superoxide dismutase (SOD) were measured by the method of xanthine oxidase and the contents of brain tissue malondialdehyde (MDA) were determined by the method of thiobarbituric acid. Neuron apoptosis was identified by TUNEL and immunohischemistry was used to detect the expression of Bci-2 and Bax protein in cerebral cortex. Results Compared with group I/R, the activity of SOD was increased significantly but the content of MDA was decreased significantly in ischemia brain tissue in every BDNF pretreatment group( P<0.05 or P <0.01 ). The index of apoptotic neuron cells and the expression of Bax protein positive cells in BDNF pretreatment groups were decreased significantly ( P <0.01) while the expression of Bcl-2 protein positive cells was increased significantly ( P <0. 01 ) in ischemia brain cortex. In high dose of BDNF pretreatment group, the SOD activity and the expression of Bcl-2 protein were the highest but the content of MDA and the expression of Bax protein and the index of apoptotic neuron ceils were the lowest( P <0. 05 or P <0. 01 ). Conclusions Different dose of BDNF pretreatment could significantly reduce the oxidative stress and neuron apoptosis following focal cerebral ischemia-reperfusion, which has varying degree cerebral protection. The protection may be related to the dose of BDNF pretreatment. The mechanism of protection may be related that BDNF pretreatment can increase the content of endogenous anti- oxidation agents and regulate the different expression of apoptosis-related gene. Key words: Brain-derived neurotrolahic factor/PD; Brain ischemia/Bl; Reperfusion injury; Oxidative stress; Apoptosis; Neuron

Effects of propofol on Akt activity in rats with focal cerebral ischemia-reperfusion injury

Objective To investigate the effects of different doses of propofol on Akt activity in the brain tissue in rats with focal cerebral ischemia-reperfusion (FC I/R) injury. Methods Ninety healthy SD rats of both sexes weighing 260-300 g were randomly divided into 5 groups (n=18 each):group Ⅰ sham operation (S);group ⅡFC I/R;group Ⅲ,Ⅳ,Ⅴ received iv propofol 1, 2, 5 mg/kg respectively + FC I/R (P1, ,P2 ,P3). FC I/R was produced by 2 h middle cerebral artery occlusion followed by 22 h reperfusian in group Ⅱ-Ⅴ. In group Ⅲ- Ⅴpropofol 1, 2 and 5 mg/kg were injected iv over 8 min starting from 3 min before reperfusion was started. Behavior was assessed using Longa score (0=no neurological deficit, 4=unable to crawl) at the end of 22 h reperfusion. Six animals were killed in each group for determination of infarct size, expression of caspase-3 (by irmnuno-histochemistry) and Akt activity (by Western blot). Results FC I/R caused cerebral infarct, significantly increased Longa score, and the expression of caspase-3 and decreased Akt activity in the brain tissue. Propofol 1 or 2 mg/kg significantly decreased the infarct size, Longa score and caspase-3 expression and increased phosphorylation of Akt in the brain tissue in group P1 and P2 as compared with group FC I/R (Ⅱ). Conclusion Propofol 1 and 2 mg/kg iv can reduce focal cerebral I/R injury by promoting phosphorylation of Akt in the brain. Key words: Propofol; Reperfusion injury; Brain; Protein kinascs

Effects of postconditioning with leg ischemia on focal cerebral ischemia-reperfusion injury in diabetic rats

Objective To evaluate the effects of leg ischemic postconditioning on focal cerebral ischemia-reperfusion (I/R) injury in diabetic rats. Methods Forty male diabetic SD rats weighing 270-320 g were randomly assigned to one of 4 groups (n=10 each):group Ⅰcontrol (C);group Ⅱ sham operation (S);group Ⅲ fecal cerebral ischemia-repertusion (I/R) and group Ⅳ leg ischemic postconditioning (IPC). Diabetes mellitus was induced by intraperitoneal streptozotocin. Local cerebral I/R was produced by middle cerebral artery occlusion (MCAO) for 1.5 h followed by 6 h reperfusion. A nylon thread with rounded tip was inserted into internal carotid artery and threaded cranially until resistance was felt. Leg isebemia was induced by placing tourniquet on beth legs at 30 min before repeffusion. The animals underwent 3 episodes of 5 min leg ischemia at 5 min intervals. Neuro-functional deficit was assessed and recorded at the end of 6h reperfusion using neurologic deficit scores (NDS) (0=no deficit, 4=unable to crawl and semiconscious). The animals were then decapitated and their brains were removed for determination of volume of cerebral infaret (by TIC staining) and ratio' of neuronal apoptosis (by TUNEL). Results NDS and cerebral infarct volume were significantly increased at the end of 6 h reperfusion in group I/R and IPC as compared with group C and S. IPC significantly decreased cerebral infarct volume and ratio of neuronal apoptosis induced by MCAO. There was no significant difference in NDA between group I/R and IPC. Conclusion Leg iscbemic postconditioning can protect the brain against focal cerebral I/R injury in diabetic rats. Key words: Lower extremity; Reperfusion injury; Brain; Diabetes mellitus; lscbemic postconditioning