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[Abstract] Objective To investigate the role of dihydromyricetin (DHM) in the treatment of ischemic stroke in rats, and to explore the effect of DHM on the expression of inflammasome. Methods The middle cerebral artery occlusion (MCAO) model was induced by endovascular suture method. The therapeutic effect and mechanism of DHM were investigated by Longa score, TTC staining, Nissl staining, immunohistochemical staining and Western bloting. Results After DHM treatment, the motor capacity of MCAO rats was significantly improved, the infarct volume was significantly reduced, the brain structure and neuron morphology were improved, and the expressions of nod-like receptor protein-3 (NLRP3) and interleukin-1(IL-1) decreased significantly. Conclusion DHM can down-regulate the expression of NLRP3 and thus reduces the cerebral infarction volume and improves neurobehavioral performance in MCAO rats.
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Objective To establish and optimize a mouse myocardial infarction (MI) model, and to use twice limb lead ECGs immediately after coronary ligation and 4 h after surgery to evaluate the occurrence of myocardial infarction. Methods Twenty-nine male C57BL/6J mice were anesthetized with isoflurane. then a myocardial infarction model was established by ligating the left anterior descending (LAD) coronary artery through the third/fourth intercostal space of left anterior chest. Immediate and 4 h postoperative limb lead ECGs were performed. Twenty-four hours after surgery, the chest was opened and the occurrence of myocardial infarction was evaluated. The heart samples were taken for TTC staining to determine the infarct area and calculate the infarct area. Results During the mice underwent coronary artery ligation the intraoperative mortality was 6.8% (2/29), and the early postoperative (<4 h) mortality was 10.3% (3/29). The 24 h survival rate was 82.8% (24/29). 24 hours after TTC staining confirmed the occurrence of infarction, the myocardial infarction model was established. The success rate of the model was 79.3% (23/29), and the average infarct size (infarcted myocardial weight / whole ventricular weight) was (28 ± 6)%; The mice successfully established by the model showed obvious ST-T changes in the ECG at 4 hours after surgery, suggesting that a myocardial infarction has occurred. Conclusions The mouse myocardial infarction model was successfully established. The combined use of ECG immediately after surgery and 4 h after surgery could be used as a rapid and non-invasive evaluation method for mouse myocardial infarction.
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Objective: To detect and evaluate the hypothalamic infarction in middle cerebral artery occlusion (MCAO) model rat. Methods: For 15 Sprague-Dawley rats weighed 200-250 g, aged 6-8 months, their right middle cerebral artery was occluded for 90 min by a silicon-coated 4-0 nylon filament and reperfused. Sprague-Dawley rats underwent diffusion weighted MR imaging (DWI) scanning (at 1 h and 24 h after reperfusion) and 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining (at 24 h after reperfusion) to determine the hypothalamic and cerebral infarct volume. The relationship between hypothalamic infarct volume and cerebral infarction volume was analyzed by DWI scanning. The results of TTC staining were compared with those of 24 h DWI scanning. Results: Fifteen Sprague-Dawley rats successfully received intraluminal MCAO/reperfusion procedures. The incidences of hypothalamic infarction on brain DWI scanning and TTC staining were 100% and 40% at 24 h after reperfusion, respectively. Therefore, DWI scanning was more sensitive than TTC staining to detect hypothalamic injury (P=0.001). The hypothalamic infarct volume on DWI scanning was (8.59±2.89) mm3 and (11.65±3.19) mm3 at 1 h and 24 h after reperfusion, respectively. On DWI scanning, hypothalamic and cerebral infarct volume at 24 h after reperfusion were correlated with each other significantly (r=0.573, P=0.025), so were the increases of hypothalamic and cerebral infarct volume (r=0.554, P=0.032) from 1 h to 24 h. Conclusion: DWI scanning was more sensitive than TTC staining to detect hypothalamic injury in intraluminal transient MCAO model. Hypothalamic and cerebral infarct volume were correlated with each other.
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Objective To observe the effects of Batroxobin Injection on thromboembolic cerebral stroke by magnetic resonance imaging (MRI) and TTC staining.Methods Rat model ofthromboembolic stroke was prepared after the left middle cerebral artery was occluded by autologous blood clots,and 32 rats with successful operation were divided into four groups according to the degree of neurological deficit:model group,Batroxobin Injection low and high dose (0.3,1.0 BU/kg) group,and rt-PA (9 mg/kg) group,with eight rats in each group,and other eight rats in Sham group.Rats were administered 1 h after modeling by tail iv method.At 6 h after administration,neurological deficit score and MRIincluding SE-T2WI and DWI sequence scanning were measured.At 24 h after administration,the brain was cut for TTC staining to measure the infarct area,and blood FIB was measured.Results Compared with model group,Batroxobin Injection 0.3 BU/kg treatment for 24 h (P ＜ 0.05),1 BU/kg treatment for 6 and 24 h (P ＜ 0.05,0.01) could significntly improve the neurological function scores of rats.MRIresults showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the lesion range (P ＜ 0.05 and 0.01).Results of TTC stain showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the infarct size (P ＜ 0.05).Batroxobin Injection at doses of 0.3 and 1 BU/kg can significantly lower plasma FIB concentration (P ＜ 0.05,0.01,0.001) 6 and 24 h after administration.Conclusion Batroxobin Injection can improve the damaged neural function,reduce scope of lesions,decrease plasma fibrinogen,with protective effects for cerebral ischemia in rats.
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Objective To observe the effects of Batroxobin Injection on thromboembolic cerebral stroke by magnetic resonance imaging (MRI) and TTC staining.Methods Rat model ofthromboembolic stroke was prepared after the left middle cerebral artery was occluded by autologous blood clots,and 32 rats with successful operation were divided into four groups according to the degree of neurological deficit:model group,Batroxobin Injection low and high dose (0.3,1.0 BU/kg) group,and rt-PA (9 mg/kg) group,with eight rats in each group,and other eight rats in Sham group.Rats were administered 1 h after modeling by tail iv method.At 6 h after administration,neurological deficit score and MRIincluding SE-T2WI and DWI sequence scanning were measured.At 24 h after administration,the brain was cut for TTC staining to measure the infarct area,and blood FIB was measured.Results Compared with model group,Batroxobin Injection 0.3 BU/kg treatment for 24 h (P ＜ 0.05),1 BU/kg treatment for 6 and 24 h (P ＜ 0.05,0.01) could significntly improve the neurological function scores of rats.MRIresults showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the lesion range (P ＜ 0.05 and 0.01).Results of TTC stain showed that Batroxobin Injection at dose of 0.3 and 1 BU/kg significantly reduced the infarct size (P ＜ 0.05).Batroxobin Injection at doses of 0.3 and 1 BU/kg can significantly lower plasma FIB concentration (P ＜ 0.05,0.01,0.001) 6 and 24 h after administration.Conclusion Batroxobin Injection can improve the damaged neural function,reduce scope of lesions,decrease plasma fibrinogen,with protective effects for cerebral ischemia in rats.
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Aim Toinvestigatetheroleofhyperglyce-mia in cerebral ischemia/reperfusion(I/R)injury with a middle cerebral artery occlusion(MCAO)rat model anditsmechanism.Methods EightyhealthymaleSD rats were randomly assigned into sham group, I/R group (normoglycemia),hyperglycemic I/R groupⅠ(HG1 )and hyperglycemic I/R groupⅡ(HG2 ).The cerebral I/R model was established by occluding the middle cerebral artery(MCA)in rats.Hyperglycemia was induced by intraperitoneal injection of 50% glu-cose solution.Neurological deficit was determined by Ludmila Belayev test;infarct size and brain edema were measured by TTC staining;mitophagy was ob-served by double immunofluorescent staining and elec-tron microscope.The expressions of autophagy-related proteins(LC3 and Beclin-1 )and apoptosis-related pro-teins(Cyt-C,AIF,caspase-9 and caspase-3 )were ex-aminedbyWesternblotfurtherly.Results Bloodglu-cose level was controlled at 4 mmol·L-1 (normoglyce-mia),10 mmol · L-1 (HG1 ) and 20 mmol · L-1 (HG2)respectively.There were no significant differ-ences between model group and HG1 group in neuro-logical deficit scores,infarct volume and edema size(P>0. 05 ).However,these indications in HG2 group were significantly increased compared with model group (P<0. 05 ).After 3 days of reperfusion,the level of mitophagy was significantly reduced accompanied with increased mitochondria damages in HG 2 group (P <0. 05 ),and the expressions of mitochondrial related ap-optotic proteins(Cyt-C,AIF,caspase-9 and caspase-3 ) were significantly increased accordingly compared to modelgroup.Conclusions Mildhyperglycemiacan not intensify the cerebal ischemic injury.In contrast, severe hyperglycemia significantly aggravates the brain ischemic injury by inhibiting the removal of injured mi-tochondria in a manner of mitophagy,thus amplifying the mitochondrial mediated cascade damage responses.
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Aim To investigate the protective effects of hydrogen sulfide ( H2 S) on focal cerebral ischemia/reperfusion injury in rats and the possible mechanisms. Methods Male Sprague Dawley rats were divided into three groups randomly: sham-operated group, cerebral ischemia/ reperfusion ( I/R) group and sodium hydro-sulfide ( NaHS ) + I/R group. The left temporary middle cerebral artery occlusion ( MCAO ) model was established by the line-embolism method. After rats were suffered 2h/24h ischemia/reperfusion stress, the mortality rate was evaluated, and the nervous function-al defect degree was evaluated by Longe scoring, the volumes of cerebral infarction was evaluated by 2 ,3 ,5-triphenyltetrazolium chloride ( TTC) staining, and the expression of P2X7 receptor protein in brain tissue was detected by the immunofluorescence method. Results The mortality rate in NaHS + I/R rats ( 29.41%) was obviously lower than those of I/R group ( 42 . 86%) . The nervous defect scores in NaHS + I/R rats were significant lower than those of I/R group ( P <0.05 ) . The volumes of cerebral infarction in NaHS +I/R group (21.88% ±3.53%) were significant lower than those of I/R group ( 36.71% ±3.73%) ( P <0.01 ) . The results of immunofluorescence showed that the positive expression cells of P2X7 receptor protein in cerebral cortex and hippocampal CA1 area of I/R group were significantly higher than those of sham-op-erated group(P<0. 01). However, compared with I/R group, the positive expression cells of P2X7 receptor protein in cerebral cortex and hippocampal CA1 area of NaHS + I/R group were significantly decreased ( P<0. 01). Conclusions H2S exerts the neuroprotective effect on focal cerebral ischemia/reperfusion injury in rats, and the protective mechanism might be associated with down-regulating the expression of P2X7 receptor protein in brain tissue.
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OBJECTIVES: Serial changes of focal ischemic lesions as seen on magnetic resonance (MR) images and triphenyltetrazolium chloride (TTC)-stained samples of transient middle cerebral artery occlusion in a rat model were evaluated to investigate the natural course of the lesions and the feasibility of the use of each method as a monitoring tool. METHODS: Transient middle cerebral artery occlusion (MCAO) was induced in fifteen adult female Sprague Dawley rats using the method of intraluminal vascular occlusion. Two hours after MCAO was induced, reperfusion was performed. Serial MR images were obtained and the volume of the brain infarct was estimated. For macroscopic and microscopic evaluation of the ischemic lesions, the ten animals were sacrificed at different times after MCAO. The rat brains were then removed and six coronal sections were made. Each section was incubated at 37 degrees C in 2% TTC solution for 15 minutes. RESULTS: Postischemic injury evaluations that were made periodically for eight weeks revealed that the lesion volume as determined from T2 maps had reached a peak on the second day after ischemic injury and the volume decreased afterwards for one week; by the fourth week, the lesion volume again increased to stabilize initial lesion development. There were considerable discrepancies between the infarct area of the samples determined by TTC staining and the in vivo infarct area estimated from the MR images, especially for late stages. CONCLUSION: T2 map MR images, with a careful consideration of the natural course of infarction development, can provide an adequate and noninvasive means to evaluate the degree of ischemic injury under diverse experimental circumstances.
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Adulto , Animales , Femenino , Humanos , Ratas , Encéfalo , Infarto , Infarto de la Arteria Cerebral Media , Espectroscopía de Resonancia Magnética , Ratas Sprague-Dawley , Reperfusión , Accidente Cerebrovascular , Sales de TetrazolioRESUMEN
The safety and efficacy of intravenous tissue plasminogen activator(tPA) on the condition of ruling out the significant risk were studied at 6 and 12 hours after cerebral artery embolization in rabbit model. The time selection was chosen to stimulate the analogous clinical situation. The safety and effectiveness of tPA in experimental and clinical treatment of acute coronary thrombosis have been established. Tissue plasminogen activator is an endogenous fibrin-specific serine protease with the potent thrombolytic activity that has been produced recently by recombinant DNA technology. The acute cerebral thromboembolic model was induced by injecting three 0.5X1.0mm fragments of autologous arterial thromi into internal carotid artery through the intra-arterial catheter. The autologous arterial thrombi was obtained from the traumatized arterial endothelium by scratching the lumen of auricular artery using modified spinal needle. The experimental group was divided into four groups : (1) group Ia : saline-treated(1 ml/kg) control group at 6 hours after embolization(n=10), (2) group Ib : tPA-treated(1 mg/kg) at 6 hours after embolization(n=10), (3) group IIa : saline-treated control group 12 hours after embolization(n=10), (4) group Iib : tPA-treated group 12 hours after embolization(n=13). The experimental rabbits were sacrificed at 24 hours after injection of tPA(1 mg/kg) or saline(1 ml/kg) in each group. Brain was cut into 0.5 cm thick coronal sections, which were stained with triphenyltetrazolium chloride to define the areas of infarction. The transparent plastic sheets were placed on the each section, and the total area of the brain slice and the area of infarction were measured by the plannimeter(as outlined by TTC staining). The percentage area of whole brain infarction was calculated as(the sum of infarcted area/the sum of brain slice areas)x100% for each rabbit. We also observed the pathologic findings with hematoxylin-eosin staining. The results were as follows : 1) Only 1 rabbit treated with tPA at 12 hours after occlusion exhibited the gross hemorrhage. 2) The infarcted area was limited to the basal ganglia and cortex in all group. 3) The mean percentage area of whole brain infarction averaged 18.6+/-1.94% in group Ia, 6.32+/-1.02% in group Ib, and 20.8+/-3.34% in group IIa, 6.78+/-1.40% in group IIb. One-way ANOVA test of infarction size showed the significant differences(p<0.05) between the tPA-treated group and the saline-treated control group, but no difference between the groups treated with same agent. 4) Under the study of microscope, infarcted area of saline-treated control group was more extended than that of tPA-treated group. Congulation necrosis and degeneration of neuronal cells could be seen. But the infarcted area of tPA-treated group was smaller than that of saline-treated control group. Only collection of foamy macrophages adjacent the necrotic area could be seen in tPA-treated group. These results suggest that tPA therapy may be safe and efficacious during the interval of 6 to 12 hours after embolization.