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.     

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．     

Astragalus injection inhibits expression of Apaf-1 in rat hippocampus after cerebral ischemia and reperfusion

AIM: To investigate the effect of Astragalus injection on the expression of apoptotic protease-activating factor 1 (Apaf-1) in the hippocampus of global cerebral ische-mia-reperfusion rats. METHODS: Male SD rats were randomly divided into 4 groups with 30 each: sham operation group, cerebral ischemia-reperfusion group, cerebral ischemia-reperfusion+Astragalus injection group, and cerebral ischemia-reperfusion+vehicle group. The global cerebral ischemia-reperfusion model of the rats was established by 4-vessel occlusion. The rats in cerebral ischemia-reperfusion group, cerebral ischemia-reperfusion+Astragalus injection group and cerebral ischemia-reperfusion+vehicle group were further divided into 7 subsets, according to the reperfusion time of 0 h, 0.5 h, 2 h, 6 h, 24 h, 72 h and 120 h. After reperfusion, the brains were removed at the corresponding time points. The protein expression of Apaf-1 in hippocampal neurons was detected by immunohistochemistry and Western blotting. The mRNA expression of Apaf-1 was observed by RT-PCR. RESULTS: Compared with sham operation group, the expression of Apaf-1 at mRNA and protein levels at all time points except 0 h and 120 h increased obviously in cerebral ischemia-reperfusion group (P<0.05). Compared with cerebral ischemia-reperfusion group, the expression of Apaf-1 at mRNA and protein levels at all time points except 0 h and 120 h decreased obviously in cerebral ischemia-reperfusion+Astragalus injection group (P<0.05). However, those in cerebral ischemia-reperfusion+vehicle group had no obvious change (P>0.05). CONCLUSION: Astragalus injection inhibits the expression of Apaf-1 at mRNA and protein levels in hippocampus of global cerebral ischemia-reperfusion rats, thus inhibiting the apoptosis of hippocampal neurons.     

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.     

Effects of astragaloside IV on autophagy in rats with cerebral ischemia/reperfusion injury

AIM: To investigate the effects of astragaloside IV (AS-IV) on autophagy in rats with cerebral ischemia/reperfusion (I/R) injury. METHODS: The focal cerebral ischemia/reperfusion of rat left middle cerebral artery occlusion (MCAO) was induced by suture method. Male SD rats (n=70) were randomly divided into sham operation group, I/R group, solvent control group, AS-IV group, AS-IV+autophagy inhibitor (3-methyladenine, 3-MA) group, 3-MA group and autophagy activator (rapamycin, Rapa) group. Except for sham operation group, the rats in other groups were subjected to ischemia for 2 h and reperfusion for 24 h. The rats with successful modeling were selected according to Zea Longa scoring criteria. The volume of cerebral infarction was measured by TTC staining. The morphological changes of nerve cells in the rats were observed with Nissl staining. The phenomenon of autophagy was observed under transmission electron microscope. The protein expression of beclin-1 and LC3-Ⅱ was determined by Western blot. RESULTS: No neurological deficit in sham operation group was observed, and the cerebral infarction was not found. Compared with sham operation group, obvious cerebral infarction was observed, the Nissl bodies were small in size and number and stained light, typical autophagosomes were observed, and the protein expression of beclin-1 and LC3-Ⅱ was increased in I/R group (P<0.05). Compared with I/R group, the volume of cerebral infarction was decreased obviously, neurological deficit restored significantly, and the number of autophagosomes and the protein expression of beclin-1 and LC3-Ⅱ were increased in AS-IV group and Rapa group (P<0.05). However, no significant difference between solvent control group and I/R group was observed (P>0.05). Compared with AS-IV group, the neurological deficit was serious, the volume of cerebral infarction and the number of autophagosomes were increased, while the expression of beclin-1 and LC3-Ⅱ was decreased in AS-IV+3-MA group and 3-MA group (P<0.05). CONCLUSION: Astragaloside IV may play an important role in atte-nuating cerebral ischemia/reperfusion injury by activating autophagy.     

X-ray irradiation increases sensitivity of myocardium to ischemia/reperfusion injury in rats

AIM：To observe the sensitivity of myocardium to ischemia/reperfusion (I/R) injury in the rats with chest radiotherapy. METHODS：The radiation-induced heart disease model was established by local 20 Gy of X-ray irradiation in the chest. Male Wistar rats (n=42) were randomly divided into 6 groups:sham trauma group, trauma group, sham trauma+sham operation group, sham trauma +I/R group, trauma+sham operation group and trauma+I/R group. The rats were subjected to 30 min of ischemia and 1 h of reperfusion 2 week after trauma. The left ventricular developed pressure (LVDP) and ±dp/dtmax were recorded by BL-410 biological signal recording and analysis system. The serum cardiac troponin I (cTnI) and creatine kinase isoenzyme (CK-MB) were measured by ELISA. The myocardial infarct size was determined by nitroblue tetrazolium(NBT) staining method and BI2000 image analysis software. RESULTS：Compared with sham trauma+I/R group, significant decreases in LVDP and ±dp/dtmax were observed in trauma+I/R group (P<0.01) with significant increases in the infarct size and the concentrations of cTnI and CK-MB (P<0.01). CONCLUSION:Chest X-ray irradiation increases the sensitivity of myocardium to I/R injury in rats.     

Effects of Astragalus polysaccharide on expression of HSP70, PKB and P53 in rat cerebral cortex with cerebral ischemia and reperfusion

AIM:To explore the molecular effects of Astragalus polysaccharide(AP) on improving nervous functions and preventing neuronal apoptosis in rat cerebral cortex with cerebral ischemia and reperfusion. METHODS:One hundred and twenty male Wister rats were randomly divided into sham operation group(SOG), model groups(MG-1 d, 3 d and 7 d), low-dose AP treatment groups(L-APTG-1 d, 3 d and 7 d), and high-dose AP treatment groups(H-APTG-1 d, 3 d and 7 d). The right middle cerebral artery of the rats in MG and AGTG was intercepted by operation to induce ischemic brain injury. The rats in L-APTG and H-APTG were treated with AP at the doses of 5 mg/kg and 15 mg/kg by intraperitoneal injection, respectively. On the 1st day, 3rd day and 7th day after operation, those animals were sacrificed to collect the brain specimens for the study after cerebral blood flow reperfusion and determination of neurological deficit scores. The structural changes of the neurons were observed under electron microscope. Apoptosis was analyzed by flow cytometry. The protein levels of heat-shock protein 70(HSP70), protein kinase B(PKB) and P53 in cerebral corical neurons were determined by immunohistochemical staining and Western blotting. RESULTS:The neurological deficit scores and the apoptotic rate of cerebral cortical neurons in H-APTG were significantly lower than those in MG and L-APTG(P<0.05). The structures of the neurons in H-APTG, such as ribosome endoplasmic reticulum, nucleolus, Golgi complex, mitochondria, etc, were better than those in MG and L-APTG. On the 1st day, 3rd day and 7th day, the protein levels of HSP70 and PKB in cerebral cortical neurons in H-APTG were significantly higher than those in L-APTG, which were significantly higher than those in MG(P<0.05). However, the P53 protein level in H-APTG was significantly lower than that in L-APTG, which was significantly lower than that in MG(P<0.05). CONCLUSION:AP improves nervous functions and inhibits neuronal apoptosis during ischemia and reperfusion. The molecular mechanisms are associated with variations of protein expression in cerebral cortical neurons, such as promotion of HSP70 and PKB and inhibition of P53.     

Effect of naoluo xintong on expression of Fas,Fas L in hippocampus CA1 area and Fas mRNA in the cortex of frontal or parietal lobe after local cerebral ischemia/reperfusion in MCAO rats

AIM: To investigate the effets of naoluo xintong on the expression of Fas, FasL protein in hippocampus CA1 area and Fas mRNA in the cortex of frontal or parietal lobe after local cerebral ischemia/reperfusion in MCAO rats. METHODS: The local cerebral ischemia /reperfusion model was established by intraluminal thread occlusion of the middle cerebral arteries (MCAO), the middle cerebral arteries of rats were occluded for 2 hours and reperfused for 1, 3 and 7 days. The animals were divided into pseudo surgery group(sham group), model group, Yiqi group, Huoxue group and naoluo xintong group. Using the techniques of immuno-histochemical staining and in situ hybridization, the expression of Fas and FasL was observed in hippocampus CA1 area, the expression of Fas mRNA was also observed in the cortex of frontal and parietal lobe. RESULTS: A value of Fas and FasL protein expression or A value and positive unit of Fas mRNA expression in control group were higher than those in sham in hippocampus CA1 area, the cortex of frontal or parietal lobe after local cerebral ischemia/reperfusion in MCAO rats (P<0.01). A value and/or positive unit of their expression in naoluo xintong group were lower than those in control group (P<0.05 or P<0.01). A value and/or positive unit of their expression in Yiqi and Huoxue groups were higher than those in naoluo xintong group for 3 and/or 7 days (P<0.05 or P<0.01). CONCLUSION: naoluo xintong could resist neuron apoptosis, alleviate pathologic injury after local cerebral ischemia/reperfusion in MCAO rats by inhibiting the expression of Fas, FasL protein and Fas mRNA.     

Preconditioning with 3-nitropropionic acid induces rat cerebral ischemic tolerance and increases expression of glucose transporter 1 and glucose transporter 3

AIM: To explore the mechanism of 3-nitropropionic acid (3-NPA) preconditioning that induces cerebral ischemic tolerance in rats by affecting the expression of brain-type glucose transporters (GLUT1 and GLUT3) at mRNA and protein levels in cerebral tissues.METHODS: The male SD rats were used in the experiments and divided randomly into sham operation group (sham group, n=4), control group of 3-NPA preconditioning (3-NPA group, n=4), cerebral ischemia group (M group, n=16) and 3-NPA preconditioning group (IPC group, n=16). M group and IPC group were further divided into 4 subgroups according to the different reperfusion time(4 h, 12 h, 24 h and 48 h). All rats were killed at the corresponding time points. The cerebral tissues in the ischemic side (left) and coronal intermediate 1/3 of cortex were collected. The protein levels and mRNA expression of GLUT1 and GLUT3 were determined by Western blotting and RT-PCR. RESULTS: Compared with M group, the ischemic reperfusion and 3-NPA preconditioning induced the upregulation of GLUT1 and GLUT3 at protein levels with significant differences (F=5.848, P<0.05 and F=6.295, P<0.05, respectively), especially after ischemia-reperfusion for 48 h. The mRNA expression of GLUT1 in IPC group began to increase at 4 h, peaked at 48 h after reperfusion, with significant difference as compared to M group at the corresponding reperfusion time points in each group or sham group. In contrast, the mRNA expression of GLUT3 in IPC group increased at 24 h, and was the highest at 48 h as compared to cerebral ischemia group at the corresponding reperfusion time points or sham group.CONCLUSION: 3-NPA preconditioning increases the expression of GLUT1 and GLUT3 at protein and mRNA levels to maintain the energy supply in brain tissues, indicating a cerebral protective mechanism.     

Establishment and evaluation of rat heart ischemia-reperfusion injury model in vivo

AIM: To establish and evaluate a rat model of heart ischemia-reperfusion injury in vivo. METHODS: Seventy-two male Sprague-Dawley rats weighing(250±50)g were randomly divided into sham operation group(sham), ischemia-reperfusion group(I/R) and normal group. The animals were anesthetized and heparinized. Myocardial ischemia-reperfusion was induced by ligating the left anterior descending coronary artery with "U-shape tube" for 35 min followed by 120 min or 240 min reperfusion in vivo. The heart infarct size was measured by triphenyltetrazolium chloride(TTC) staining. The myocardial cell apoptotic index was determined by the method of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling(TUNEL). Immunohistochemical method was used to detect the expression of Bcl-2 and Bax in rat ischemia myocardium. The blood level of MB isoenzyme of creatine kinase(CK-MB),cardiac troponin I(cTnI),nitric oxide(NO),malondialdehyde(MDA), total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px) were detected after reperfusion for 2 h and 4 h. RESULTS: Compared with normal group and sham group, there were obvious changes of ST-T segment and Q wave in the electrocardiogram of I/R group. The blood level of CK-MB, cTnI, NO, MDA and GSH-Px in I/R group increased(P<0.05,P<0.01) after reperfusion for 2 h and 4 h, and the blood level of T-SOD in I/R group after reperfusion for 2 h and 4 h also increased(P<0.05). The heart infarct size in I/R group was the largest as compared to other groups. Among these groups, the apoptotic index of I/R group was the highest and the Bcl-2/Bax ratio in I/R group decreased(P<0.01).CONCLUSION: The rat model of heart ischemia-reperfusion injury in vivo can be successfully established with the "U-shape tube". There are obviously changes of heart infarct size, blood level of CK-MB, cTnI, NO, MDA, T-SOD and GSH-Px, myocardial apoptotic index and Bcl-2/Bax ratio between I/R rats and control animals.     

Expression of CRF and PKC proteins in hippocampus of rats with cerebral ischemia and reperfusion

AIM: To observe the expression of CRF and PKC in rats with cerebral ischemia.METHODS: Using immunohistochemistry technique we measured the expression quantitatively of CRF and PKC proteins in the hippocampus in rats induced by MCAO at 2 h,6 h and 24 h after reperfusion,contrast to CRF antagonist.RESULTS: (1) CRF: there were lots of positive and deeper dyeing neurons in hippocampus in model group and normal saline group rats,while there were a few positive and lighter dyeing neurons in sham group and CRF antagonist group.The positive expression areas of CRF protein in hippocampus in model group and normal saline group were significantly bigger than those in sham group and CRF-antagonist group(P<0.01),respectively.(2) PKC：there were a great number of denser positive granules in hippocampus in model group and normal saline group rats,while there were a few of scattered positive granules in sham group and CRF antagonist group.The positive expression areas of CRF protein in hippocampus in model group and normal saline group were significantly bigger than that in sham group and CRF-antagonist group (P<0.01),respectively.CONCLUSION: The high expression of CRF and PKC induced by cerebral ischemia may be one important factors that resulted in the delayed neuronal death in hippocampus.The CRF protein activated PKC expression,indicating an important pathology mechanism of nerve tissue damage induced by CRF.     

Effects of adrenal gland on the expression of bax and bcl-2 in hippocampus after cerebral ischemia

AIM: To observe the effects of adrenal gland on the hippocampus responses to cerebral ischemia. METHODS: 36 Wistar rats were randomly divided into three groups: sham-operated control group (sham), unilateral adrenalectomy were performed in ADX and GC group, and GC group were injected with 5 mg/per rat of dexamethasone before cerebral ischemia. Fourteen days after the first operation, all animals were performed occlusion of bilateral carotid artery for 15 min, and then reperfusion. 3 rats of each group were sacrificed at 1 h, 4 h, 8 h and 24 h after reperfusion and hippocampus were dissected. The total RNA was rapidly extracted from hippocampus tissue. The expressions of c-fos, bcl-2 and bax gene were quantified with the method of semiquantitive RT-PCR. RESULTS: The expressions of c-fos and bax in three groups showed no statistical differences (P>0.05). The expression of bcl-2 in sham group was significantly higher than that in GC and ADX groups (P<0.05). However, no differences of bcl-2 expression between GC and ADX group (P>0.05) was observed. The ratio of bax to bcl-2 in sham group was significantly lower than that in GC and ADX groups (P<0.05), no significant differences of the ratio displayed between ADX and GC group. CONCLUSION: The expression of c-fos and bax in hippocampus after cerebral ischemia is not affected by adrenal gland. The excision of unilateral adrenal gland downregulates bcl-2 expression and raises the ratio of bax to bcl-2 in rat hippocampus after cerebral ischemia. Dexamethasone treatment does not alter the expression of bcl-2 in ADX and GC groups. The results indicate that the adrenal gland can counteract cell apoptosis in hippocampus tissue induced by cerebral ischemia. Adrenal steroids are not sufficient to enable the compensatory increase in bcl-2 expression in steroid-deficient animal, some other mechanism may exist.     

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.     

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.     

Effects of ghrelin on brain edema and aquaporin 4 expression after cerebral ischemia/reperfusion in rats

AIM: To explore the effects of ghrelin on the brain edema, the permeability of blood-brain barrier (BBB) and the expression of aquaporin 4 (AQP4) after cerebral ischemia/reperfusion in rats. METHODS: Adult male Sprague-Dawley rats were randomly divided into sham operation group, middle cerebral artery occlusion (MCAO) group and ghrelin treatment group. The MCAO model was made with nylon thread for 2 h of occlusion following 22 h of reperfusion. Ghrelin at a dose of 10 nmol/kg was injected via femoral vein at the beginning of reperfusion. The cerebral infarct volume was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Brain functional deficits were evaluated by determining the neurological scores. The changes of brain swelling and water content were analyzed through volume calculation and dry/wet weight measurement. The permeability of BBB was detected by collecting extravascular Evans blue (EB) in the brain cortex. The changes of AQP4 expression were assessed by the methods of immunohistochemistry and Western blotting. RESULTS: Compared with MCAO group, the rats in ghrelin treatment group had smaller brain infarct volume, lower EB exudation content and neurological scores. The percentage of brain swelling, water content and AQP4 expression were lower in ghrelin treatment group than those in MCAO group. CONCLUSION: Ghrelin reduces the injury of cerebral ischemia/reperfusion, and lightens the brain edema and BBB damage in rats. Ghrelin also inhibits the expression of AQP4 in brain tissue.     

Effects of Xingnaojing injection on expression of ZO-1 in blood-brain barrier after global ischemia-reperfusion

AIM: To investigate the effect of Xingnaojing (XNJ) injection on the permeability of blood-brain barrier (BBB) and zonula occludens-1 (ZO-1) protein expression after global ischemia-reperfusion in rats. METHODS: Improved Pulsinelli four-vessel occlusion method was adopted to establish the global ischemia-reperfusion model in the rats. Male Wistar rats were randomly divided into sham group, model group, solvent group and XNJ group. The observations were conducted at the time points of 24 h, 48 h and 72 h after ischemia reperfusion. The water content of the brain tissues was determined by dry-wet weight method, while the Evans blue (EB) content of brain tissue was detected by spectrophotometry. The protein levels of ZO-1 in the cerebral cortex were analyzed by Western blot. RESULTS: The water contents in the brain tissues in model group, solvent group and XNJ group were significantly higher than those in sham group (P<0.05) 24 h after ischemia reperfusion. However, the brain water contents in model group and solvent group were significantly higher than those in XNJ group and sham group (P<0.05) 48 h and 72 h after ischemia reperfusion. The EB contents in the brain tissues in model group, solvent group and XNJ group were entirely higher than that in sham group 24 h after ischemia reperfusion (P<0.05). The EB contents in sham group and XNJ group were significantly lower than those in model group and solvent group 48 h and 72 h after ischemia reperfusion (P<0.05). The protein expression of ZO-1 in the rat cerebral cortex in model group, solvent group and XNJ group was significantly lower than that in sham group 24 h after ischemia-reperfusion (P<0.05). Similarly, 48 h and 72 h after ischemia reperfusion, ZO-1 protein level in the cortex in sham group and XNJ group was significantly higher than that in model group and solvent group (P<0.05). CONCLUSION: At 48 h and 72 h after global ischemia-reperfusion, Xingnaojing injection play a protective role in blood-brain barrier and this role may be associated with the increase in ZO-1 protein expression by Xingnaojing injection.     

Protective effect of pentoxifylline against spinal cord ischemia/reperfusion injury in rabbits

AIM: To investigate the protection of pentoxifylline against spinal cord ischemia/reperfusion injury.METHODS: Rabbits sustained spinal cord ischemia with 45 min cross-clamping of the infrarenal aorta. Groups were as follows: sham operation (n=8); ischemic control (n=20), receiving only vehicle; PTX A (n=20), receiving PTX before clamping and PTX B (n=20), receiving PTX at the onset of reperfusion. Rabbits were evaluated for hind-limb motor function with the Tarlov scoring system at 48 h. Serum was assayed with ELISA for TNF-α and spinal cords were harvest for MPO activity, histopathologic analysis and TUNEL staining. Immunohistochemistry was used for PECAM-1 and caspase-3 detection, and the numbers of necrosic and apoptotic neuron were counted at 12 h, 24 h, 48 h and 72 h of reperfusion. The necrotic and apoptotic neurons were also observed with transmission electron microscope.RESULTS: Improved Tarlov scores were observed in PTX-treated rabbits as compared with ischemic control rabbits at 48 h. The significant reductions of TNF-α in serum, activity of MPO, immunoreactivity of the PECAM-1 and caspase-3 were found in PTX-treated rabbits. The numbers of necrosic and apoptotic neuron were higher in PTX-treated rabbits than that in the ischemic control rabbits (P<0.05). No necrosic and apoptotic neuron were found in the sham operation group. CONCLUSION: PTX induces protection against ischemia/reperfusion injury in the spinal cord, thereby preventing both necrosis and apoptosis.     

Knockdown of Atg5 aggravates cerebral ischemia and reperfusion injury in mice

AIM: To study the role of autophagy-related gene 5 (Atg5) in cerebral ischemia and reperfusion injury in mice. METHODS: BALB/c male mice (weighing 18~22 g) were randomly divided into sham group, ischemia/reperfusion (I/R) group, Atg5 siRNA group and control siRNA group. Focal cerebral ischemia was performed using the method of middle cerebral artery occlusion (MCAO) for 60 min and reperfusion for 24 h. In siRNA group and control group, 5 μL Atg5 siRNA or scrambled siRNA was administered by intracerebroventricular injection 24 h before MCAO. The expression of Atg5 at mRNA and protein levels in ischemic cortex at 24 h after reperfusion was determined by real-time PCR and Western blot. The infarct volume and edema were evaluated by TTC staining, and motor deficits were evaluated by neurological scoring. RESULTS: The expression of Atg5 at mRNA and protein levels was significantly increased 24 h after reperfusion in I/R group compared with sham group. Atg5 siRNA obviously decreased the expression of Atg5 at mRNA and protein levels induced by I/R. Inhibition of Atg5 exacerbated the infarct volume and ameliorated the neurological symptoms. CONCLUSION: Atg5 has neuroprotective effect on focal cerebral ischemia and reperfusion injury.