Neuroendocrine mechanism for tolerance to cerebral ischemia-reperfusion injury in male rats

Testosterone has been shown to exacerbate cerebral ischemia-reperfusion injury, which suggests that the well-known stress-induced testosterone reduction could be a protective response. We hypothesized that stress-induced testosterone reduction contributes to ischemia tolerance in cerebral ischemia-reperfusion injury in male rats. In intact male rats, stress was induced by brief anesthesia at 6 h before transient middle cerebral artery occlusion (MCAO). Testosterone levels were significantly decreased 6 h after stress. Testosterone reduction was associated with a 50% reduction in cerebral lesion volume in the stressed animals. Further, the stress-induced cerebral ischemia tolerance was eliminated by testosterone replacement in castrated males. Immunohistochemical staining showed that androgen receptors were up-regulated after cerebral ischemia-reperfusion injury and partially colocalized with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells in the parietal cortex and extensively colocalized in the caudate putamen. Heat shock protein 70 (Hsp70) and 90 (Hsp90) are involved in ischemia tolerance, and were not colocalized with TUNEL in the immunohistochemical staining, suggesting an antiapoptotic role of Hsp's. To determine the effect of testosterone on MCAO-induced Hsp70 and -90 expression, a testosterone replacement or withdrawal paradigm was used. Testosterone-replaced animals exhibited a decrease in Hsp expression, whereas testosterone withdrawal (mimicking the stress-induced testosterone suppression) normalized this deficit. In summary, stress-induced testosterone reduction contributes to ischemia tolerance in cerebral ischemia-reperfusion injury in males, which could be related to the loss of inhibition by testosterone of Hsp70 and -90 expression.     

Neuroendocrine mechanism for tolerance to cerebral ischemia‐reperfusion injury in male rats

Testosterone has been shown to exacerbate cerebral ischemia‐reperfusion injury, which suggests that the well‐known stress‐induced testosterone reduction could be a protective response. We hypothesized that stress‐induced testosterone reduction contributes to ischemia tolerance in cerebral ischemia‐reperfusion injury in male rats. In intact male rats, stress was induced by brief anesthesia at 6 h before transient middle cerebral artery occlusion (MCAO). Testosterone levels were significantly decreased 6 h after stress. Testosterone reduction was associated with a 50% reduction in cerebral lesion volume in the stressed animals. Further, the stress‐induced cerebral ischemia tolerance was eliminated by testosterone replacement in castrated males. Immunohistochemical staining showed that androgen receptors were up‐regulated after cerebral ischemia‐reperfusion injury and partially colocalized with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells in the parietal cortex and extensively colocalized in the caudate putamen. Heat shock protein 70 (Hsp70) and 90 (Hsp90) are involved in ischemia tolerance, and were not colocalized with TUNEL in the immunohistochemical staining, suggesting an antiapoptotic role of Hsp's. To determine the effect of testosterone on MCAO‐induced Hsp70 and ‐90 expression, a testosterone replacement or withdrawal paradigm was used. Testosterone‐replaced animals exhibited a decrease in Hsp expression, whereas testosterone withdrawal (mimicking the stress‐induced testosterone suppression) normalized this deficit. In summary, stress‐induced testosterone reduction contributes to ischemia tolerance in cerebral ischemia‐reperfusion injury in males, which could be related to the loss of inhibition by testosterone of Hsp70 and ‐90 expression. © 2004 Wiley Periodicals, Inc. J Neurobiol, 2005     

梓醇对大鼠脑缺血再灌注损伤的保护作用研究

目的:探讨梓醇对缺血再灌注大鼠脑损伤后的保护作用.方法:采用传统大脑中动脉阻塞(MCAO)方法制备大鼠局灶性缺血模型,根据随机数字表法将SD大鼠分为MCAO组、对照组(vehicle组)及梓醇处理组(catalpol组),缺血再灌注48 h后观察各组大鼠神经功能学评分和脑梗死容积.分别于术前、术后6h、24 h、48 h取大鼠脑组织样本,检测匀浆中谷胱甘肽过氧化物酶(GSH-PX)和丙二醛(MDA)的变化情况.结果:与vehicle组和MCAO组相比,catalpol处理组神经功能学评分降低(P＜0.05);其梗死容积较小(P＜0.05).组织匀浆结果显示catalpol处理组脑匀浆中GSH-PX活力升高,MDA含量下降(P＜0.05).结论:梓醇可能通过降低脑内自由基水平、控制脂质过氧化程度,对缺血再灌注引起的大鼠脑损伤产生神经保护作用.     

蜂胶黄酮对大鼠脑缺血再灌注损伤后IL-1β、IL-6和TNF-α含量的影响

目的探讨蜂胶黄酮对脑缺血再灌注损伤的保护作用。方法采用大鼠大脑中动脉栓塞模型（MCAO）,研究蜂胶黄酮对脑缺血再灌注脑梗死体积和行为学评分的影响,对脑组织内IL-1β、IL-6和TNF-α含量的影响。结果蜂胶黄酮能够减少MCAO脑梗死体积和行为学评分,降低脑组织中IL-1β、IL-6和TNF-α的含量（P〈0．05）。结论蜂胶黄酮对大鼠脑缺血再灌注损伤有一定保护作用,其作用机制与降低脑组织中IL-1β、IL-6和TNF-α含量有关。     

Experimental stroke: ischaemic lesion volume and oedema formation differ among rat strains (a comparison between Wistar and Sprague-Dawley rats using MRI)

Investigating focal cerebral ischaemia requires animal models that are relevant to human stroke. This study was designed to evaluate the influence of early reperfusion and choice of rat strains on infarct volume and oedema formation. Thirty-six Wistar and Sprague-Dawley rats were subjected to temporary middle cerebral artery occlusion (MCAO) for 90 min (groups I and II) or to permanent MCAO (groups III and IV) using the suture technique. Ischaemic lesion volume and oedema formation were quantified 24 h after MCAO using 7T-magnetic resonance imaging (MRI). Impact of rat strains: Reperfusion led to significant larger ischaemic lesion volumes in Wistar rats as compared to Sprague-Dawley rats (P<0.0005). Oedema formation was similar in both rat strains. Permanent MCAO led to significantly larger ischaemic lesion volumes in Sprague-Dawley rats (P<0.05). Oedema formation, however, was significantly more accentuated in Wistar rats (P<0.005). Impact of reperfusion: Reperfusion did not cause any changes in ischaemic lesion volume in Wistar rats. Oedema formation, however, was significantly reduced (P<0.0005). In Sprague-Dawley rats, reperfusion caused a significant reduction of ischaemic lesion volume (P<0.00005), but did not modify oedema formation. These findings emphasize the critical importance of rat strain differences in experimental stroke research.     

Homer1a基因敲除对小鼠局灶性脑缺血再灌注损伤的作用

目的:通过研究homer1a基因敲除小鼠脑缺血再灌注损伤及海马区星形胶质细胞活化、数目形态变化,探讨homer1a基因在脑缺血损伤中的作用及机制。方法:取雄性homer1a基因敲除(Knock Out,KO)小鼠及同窝野生型(Wild Type,WT)小鼠各15只,分为基因敲除假手术组(Sham Knock Out,SKO,n=3)、基因敲除型缺血2 h再灌注24 h组(Model Knock Out,MKO,n=12)、野生型假手术组(Sham Wild Type,SWT,n=3)及野生型缺血2 h再灌24h组(Model Wild Type,MWT,n=12)。线栓法闭塞小鼠大脑中动脉制作脑缺血再灌注损伤模型(middle cerebral artery occlusion and reperfusion,MCAO/R),在缺血再灌注损伤前(0 h)及缺血再灌注后3 h、6 h、12 h、24 h后进行改良版神经损伤严重性评分(modified Neurological severity scores,m NSS)、2,3,5—氯化三苯基四氮唑(2,3,5triphenyltetrazolium chloride,TTC)染色、苏木素—伊红染色(Hematoxylin-eosin staining,HE)、原位末端转移酶标记技术(terminal deoxynucleotidyl transferase(Td T)-mediated deoxyuridine triphosphate(d UTP)nick end labeling,TUNEL)检测及免疫荧光染色观察海马区星形胶质细胞神经纤维酸性蛋白(Glial Fibrillary Acidic Protein,GFAP)改变。结果:SKO组、SWT组行为学m NSS评分均为0分,TTC染色未见梗死灶。TUNLE及GFAP染色阳性细胞数很少且未见统计学差异(P0.05)。脑缺血再灌注24 h后,MKO组m NSS评分较MWT组高;TTC染色MKO组较MWT组梗死百分比高;MKO组较MWT组TUNEL凋亡率高;GFAP免疫荧光染色阳性数MKO组少于MWT组,且均有统计学差异(P0.05)。结论:homer1a基因敲除加重了小鼠脑缺血再灌注损伤,星形胶质细胞可能参与并发挥复杂作用。     

A surgical model of permanent and transient middle cerebral artery stroke in the sheep

Background

Animal models are essential to study the pathophysiological changes associated with focal occlusive stroke and to investigate novel therapies. Currently used rodent models have yielded little clinical success, however large animal models may provide a more suitable alternative to improve clinical translation. We sought to develop a model of acute proximal middle cerebral artery (MCA) ischemic stroke in sheep, including both permanent occlusion and transient occlusion with reperfusion.

Materials and Methods

18 adult male and female Merino sheep were randomly allocated to one of three groups (n = 6/gp): 1) sham surgery; 2) permanent proximal MCA occlusion (MCAO); or 3) temporary MCAO with aneurysm clip. All animals had invasive arterial blood pressure, intracranial pressure and brain tissue oxygen monitoring. At 4 h following vessel occlusion or sham surgery animals were killed by perfusion fixation. Brains were processed for histopathological examination and infarct area determination. 6 further animals were randomized to either permanent (n = 3) or temporary MCAO (n = 3) and then had magnetic resonance imaging (MRI) at 4 h after MCAO.

Results

Evidence of ischemic injury in an MCA distribution was seen in all stroke animals. The ischemic lesion area was significantly larger after permanent (28.8%) compared with temporary MCAO (14.6%). Sham animals demonstrated no evidence of ischemic injury. There was a significant reduction in brain tissue oxygen partial pressure after permanent vessel occlusion between 30 and 210 mins after MCAO. MRI at 4 h demonstrated complete proximal MCA occlusion in the permanent MCAO animals with a diffusion deficit involving the whole right MCA territory, whereas temporary MCAO animals demonstrated MRA evidence of flow within the right MCA and smaller predominantly cortical diffusion deficits.

Conclusions

Proximal MCAO can be achieved in an ovine model of stroke via a surgical approach. Permanent occlusion creates larger infarct volumes, however aneurysm clip application allows for reperfusion.     

Application of in vivo ESR spectroscopy to measurement of cerebrovascular ROS generation in stroke

This study used an in vivo ESR spectroscopy/spin probe technique to measure directly the generation of reactive oxygen species (ROS) in the brain after cerebral ischemia-reperfusion. Transient middle cerebral artery occlusion (MCAO) was induced in rats by inserting a nylon thread into the internal carotid artery for 1 h. The in vivo generation of ROS and its location in the brain were analyzed from the enhanced ESR signal decay data of three intra-arterially injected spin probes with different membrane permeabilities. The ESR signal decay of the probe with intermediate permeability was significantly enhanced 30 min after reperfusion following MCAO, whereas no enhancement was observed with the other probes or in the control group. The enhanced in vivo signal decay was significantly suppressed by superoxide dismutase (SOD). Brain damage was barely discernible until 3 h of reperfusion, and was clearly suppressed with the probe of intermediate permeability. The antioxidant MCI-186 completely suppressed the enhanced in vivo signal decay after transient MCAO. These results clearly demonstrate that ROS are generated at the interface of the cerebrovascular cell membrane when reperfusion follows MCAO in rats, and that the ROS generated during the initial stages of transient MCAO cause brain injury.     

Neuroprotective effects of NU1025, a PARP inhibitor in cerebral ischemia are mediated through reduction in NAD depletion and DNA fragmentation

Oxidative stress induced cell injury is reported to contribute to the pathogenesis of cerebral ischemia. Reactive oxygen species such as hydrogen peroxide (H2O2) and superoxide radical along with nitric oxide and peroxynitrite generated during ischemia-reperfusion injury, causes the overactivation of poly (ADP-ribose) polymerase (PARP) leading to neuronal cell death. In the present study we have evaluated the effects of PARP inhibitor, 8-hydroxy-2 methyl-quinazolin-4-[3H]one (NU1025) in H2O2 and 3-morphilinosyndonimine (SIN-1) induced cytotoxicity in PC12 cells as well as in middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia in rats. Exposure of PC12 cells to H2O2 (0.4 mM) and SIN-1 (0.8 mM) resulted in a significant decrease in cell viability after 6 h. Pretreatment with NU1025 (0.2 mM) restored cell viability to approximately 73 and 82% in H2O2 and SIN-1 injured cells, respectively. In MCAO studies, NU1025 was administered at different time points (1 h before reperfusion, immediately before reperfusion, 3 h after reperfusion and 6 h after reperfusion). NU1025 at 1 and 3 mg/kg reduced total infarct volume to 25% and 45%, respectively, when administered 1 h before reperfusion. NU1025 also produced significant improvement in neurological deficits. Neuroprotection with NU1025 was associated with reduction in PAR accumulation, reversal of brain NAD depletion and reduction in DNA fragmentation. Results of this study demonstrate the neuroprotective activity of NU1025 and suggest its potential in cerebral ischemia.     

毛蕊异黄酮通过抑制calpain-1的表达发挥抗脑缺血再灌注损伤的研究

目的:探讨毛蕊异黄酮抗脑缺血再灌注损伤的作用是否与抑制calpain-1的表达有关。方法:将SD大鼠随机分为假手术组、模型组以及药物组,采用线栓法建立大鼠大脑中动脉阻断(MCAO)模型,于缺血再灌注前30 min腹腔注射给予20 mg/kg毛蕊异黄酮或等体积的溶剂。再灌注24 h后,行神经功能学评分、脑梗死面积以及神经元凋亡检测;再灌注12 h、24 h时,采用免疫组化和蛋白印迹技术检测大鼠脑皮层calpain-1的表达。结果:与假手术组大鼠比较,MCAO模型组大鼠再灌注24 h后神经功能学评分、梗死面积、神经元凋亡率及calpain-1的表达均明显升高(P0.05),而毛蕊异黄酮能够降低模型组大鼠再灌注24 h后神经功能学评分、梗死面积、神经元凋亡率以及calpain-1的表达(P0.05)。结论:毛蕊异黄酮可能通过抑制calpain-1的表达发挥抗脑缺血再灌注损伤作用。     

Neuroprotective effects of VEGF administration after focal cerebral ischemia/reperfusion: dose response and time window

Administration of vascular endothelial growth factor (VEGF) has been shown to increase cerebral blood flow and reduce neurological damage after experimental ischemic brain injury. The purpose of this study was to examine the optimal dose and time window for the neuroprotective effect of VEGF when administrated after focal ischemia/reperfusion injury in rabbits. Focal cerebral ischemia/reperfusion was induced by the middle cerebral artery occlusion (MCAO) method. In a dose response experiment, low (1.25 ng/μL), middle (2.5 ng/μL) and high (5.0 ng/μL) doses of VEGF were administered 2h after MCAO by the route of perifocal region. The VEGF at a dose of middle (2.5 ng/μL) displayed excellent effects on neuroprotective efficacy for focal cerebral ischemia/reperfusion injury. In another experiment, 2.5 ng/μL VEGF was administered at times varying from 2 to 8h after MCAO. Infarct volume, water content and neurological deficits were significantly reduced when VEGF was given at 2 and 3h after injury. The protective effect was less when the same dose was given at the later times. Thus, the present findings indicated that VEGF reduced ischemic neuronal danger with a therapeutic time window within the first 3h of transient MCAO and may be useful in the treatment of acute ischemic stroke in humans.     

Theaflavin ameliorates cerebral ischemia-reperfusion injury in rats through its anti-inflammatory effect and modulation of STAT-1

Theaflavin, a major constituent of black tea, possesses biological functions such as the antioxidative, antiviral, and anti-inflammatory ones. The purpose of this study was to verify whether theaflavin reduces focal cerebral ischemia injury in a rat model of middle cerebral artery occlusion (MCAO). Male Sprague-Dawley rats were anesthetized and subjected to 2 hours of MCAO followed 24 hours reperfusion. Theaflavin administration (5, 10, and 20 mg/kg, i.v.) ameliorated infarct and edema volume. Theaflavin inhibited leukocyte infiltration and expression of ICAM-1, COX-2, and iNOS in injured brain. Phosphorylation of STAT-1, a protein which mediates intracellular signaling to the nucleus, was enhanced 2-fold over that of sham group and was inhibited by theaflavin. Our study demonstrated that theaflavin significantly protected neurons from cerebral ischemia-reperfusion injury by limiting leukocyte infiltration and expression of ICAM-1, and suppressing upregulation of inflammatory-related prooxidative enzymes (iNOS and COX-2) in ischemic brain via, at least in part, reducing the phosphorylation of STAT-1.     

Effects of ulinastatin, a urinary trypsin inhibitor, on synaptic plasticity and spatial memory in a rat model of cerebral ischemia/reperfusion injury

Established therapies for cerebral ischemia-reperfusion injury are currently limited. The urinary trypsin inhibitor ulinastatin (UTI) is considered cytoprotective against ischemia-reperfusion injury in internal organs through its anti-inflammatory activity. We aimed to investigate the neuroprotective effects of UTI on learning and memory of rats after cerebral ischemia-reperfusion injury. Rats were treated with UTI at 10,000 U/kg body weight, then underwent ischemia and reperfusion by the middle cerebral arterial occlusion (MCAO) method. At various times after the onset of reperfusion, we evaluated neurologic impairment scores. Brain sections underwent immunohistochemical staining for synaptophysin and calcium-binding protein S100β. Other rats underwent the Morris water maze test to determine the effects of UTI on learning and memory. Spatial reference learning and memory were improved with UTI treatment by down-regulating S100β-positive cells and preventing the loss of neural cells. Thus, UTI has a neuroprotective role on synaptic plasticity and spatial memory with cerebral ischemia-reperfusion injury in rats.     

15-HETE参与的脑缺血再灌注损伤中p-ERK1/2表达变化的研究

目的:通过应用15-脂氧化酶(15-Lipoxygenase,15-LOX)抑制剂去甲二氢愈创木酸(nordihydroguaiaretic acid,NDGA)抑制15-羟基-二十碳四烯酸(15-hydroxyeicosatetraenoic acid,15-HETE)的生成,观察缺血再灌注损伤中大鼠脑组织磷酸化细胞外信号调节酶(phosphor-extracellular signal-regulated kinase,p-ERK1/2)表达的变化,探讨p-ERK1/2在15-HETE参与的脑缺血再灌注损伤中的作用及其表达变化。方法:应用大脑中动脉线栓栓塞法(MCAO)制作大鼠脑梗死2小时再灌注模型。将大鼠随机分为三组:假手术组(sham组)、DMSO对照组、NDGA处理组。后两组再根据不同的灌注时间分为三个亚组:再灌注1小时组、再灌注6小时组、再灌注24小时组。采用TTC染色法检测再灌注24小时大鼠脑梗死体积;免疫印迹(Western blot)法测定梗死后再灌注不同时间点梗死核心区和梗死周围区的p-ERK1/2的表达。结果:假手术组仅有少量p-ERK1/2的表达。DMSO对照组梗死核心区p-ERK1/2的表达从梗死再灌注后1小时即开始逐渐升高(1.43±0.06),6小时达高峰(2.02±0.14),24小时有所下降(1.16±0.21),与假手术组(0.62±0.08)比较P值均0.01;梗死周围区p-ERK1/2表现出相同的变化趋势。与DMSO对照组比较,NDGA处理组大鼠脑梗死体积显著减小(20.10±0.12%vs 17.24±0.16%,P=0.009,P0.05),各时间点p-ERK1/2的表达均下降。与梗死核心区相比较,梗死周围区24小时仍可检测到较高含量的p-ERK1/2(1.16±0.21 vs 1.86±0.14),但梗死核心区表达相对较少。结论:脑缺血再灌注损伤中,p-ERK1/2的表达增加,说明p-ERK1/2参与其中;应用NDGA后,p-ERK1/2的表达降低,脑梗死体积减小,证实p-ERK1/2参与了15-HETE介导的脑缺血再灌注损伤,并在此过程中可能参与了细胞的凋亡。     

阿司匹林对糖尿病大鼠肾缺血再灌注损伤时Cystatin C 的影响

目的:评价阿司匹林对糖尿病大鼠肾缺血再灌注损伤后Cystatin C(蛋白酶抑制肽C)的影响。方法:32只成年Sprague-Dawley大鼠经链脲霉素(streptozotocin,STZ)腹腔注射建立糖尿病模型后随机分为4组,实验组分别经胃灌注10 mg/kg、20 mg/kg、30 mg/kg的阿司匹林,对照组灌注等量生理盐水15 d后建立肾缺血30 min再灌注2 h模型。抽取动脉血用ELISA法检测Cystatin C水平,取肾脏做病理切片和免疫组化检测。结果:各实验组血清Cystatin C水平明显低于对照组(P0.05),实验组之间差异不显著(P0.05)。HE染色实验组与对照组未见明显组织病理学差异。免疫组化显示对照组Cystatin C蛋白表达增多,而实验组表达不显著。结论:低剂量阿司匹林降低STZ诱导的糖尿病大鼠肾缺血再灌注后血浆Cystatin C水平,具有肾保护作用。     

Calcitonin gene-related peptide prevents blood-brain barrier injury and brain edema induced by focal cerebral ischemia reperfusion

Cerebral ischemia is one of the diseases that most compromise the human species. Therapeutic recovery of blood-brain barrier (BBB) disruption represents a novel promising approach to reduce brain injury after stroke. To determine the effects of calcitonin gene-related peptide (CGRP) on the BBB participate in stroke progression, rat cerebral ischemia reperfusion injury was induced by a 2-hour left transient middle cerebral artery occlusion (MCAO) using an intraluminal filament, followed by 46h of reperfusion. CGRP (1μg/ml) at the dose of 3μg/kg (i.p.) was administered at the beginning of reperfusion. Subsequently, 48h after MCAO, arterial blood pressure, infarct volume, water content, BBB permeability, BBB ultrastructure, levels of aquaporin-4 (AQP4) and its mRNA were evaluated. CGRP could reduce arterial blood pressure (P<0.001), infarct volume (P<0.05), cerebral edema (P<0.01), BBB permeability (P<0.05), AQP4 mRNA expression (P<0.05) and AQP4 protein expression (P<0.01). Furthermore, CGRP treatment improved ultrastructural damage of capillary endothelium cells and decreased the loss of the tight junction observed by transmission electronic microscopy (TEM) after 46h of reperfusion. Our findings show that CGRP significantly reduced postischemic increase of brain edema with a 2-hour therapeutic window in the transient model of focal cerebral ischemia. Moreover, it seems that at least part of the anti-edematous effects of CGRP is due to decrease of BBB disruption by improving ultrastructural damage of capillary endothelium cells, enhancing basal membrane, and inhibiting AQP4 and its mRNA over-expression. The data of the present study provide a new possible approach for acute stroke therapy by administration of CGRP.     

吗啡对脑缺血再灌注损伤后神经元凋亡及Bcl-2的影响

目的:探讨吗啡预处理对大鼠脑缺血再灌注损伤后神经元凋亡及Bcl-2蛋白表达的影响.方法:Wistar大鼠随机分为假手术组、模型组、吗啡组,各18只.四动脉阻断法建立脑缺血模型,吗啡组在脑缺血前60 min腹腔内注射吗啡1mg/kg.脑缺血8 min再灌注12h、72h及168h各取6只大鼠的脑组织,观察海马区病理学改变、神经元凋亡及Bcl-2表达.结果:吗啡预处理能使各灌注点海马神经元病理改变减轻、凋亡细胞数减少(P<0.01)、Bel-2表达增加(P<0.01).吗啡组细胞凋亡数减少趋势与Bcl-2表达上调趋势一致.结论:吗啡预处理可减轻缺血性脑损伤;吗啡抗凋亡作用机制与Bcl-2密切相关.     

Early Treatment with Poly(ADP-Ribose) Polymerase-1 Inhibitor (JPI-289) Reduces Infarct Volume and Improves Long-Term Behavior in an Animal Model of Ischemic Stroke

In patients with stroke and neurodegenerative diseases, overactivation of poly(ADP-ribose) polymerase-1 (PARP-1) causes harmful effects by inducing apoptosis, necrosis, neuroinflammation, and immune dysregulation. The current study investigated the neuroprotective effect of a novel PARP-1 inhibitor, JPI-289, in an animal model of ischemic stroke. A transient middle cerebral artery occlusion (tMCAO, 2 h) model was used to determine the therapeutic effect and the most effective dose and time window of administration of JPI-289. We also investigated the long-term outcomes of treatment with JPI-289 by diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) MRI and by measuring neurological function at 24 h, 7 days, and 28 days after MCAO. The most effective dose and time window of administration of JPI-289 was 10 mg/kg administered 2 h after MCAO with reperfusion. Twenty-four hours after MCAO, infarct volume was reduced by 53% and the number of apoptotic cells was reduced by 56% compared with control. JPI-289 also reduced infarct volume by 16% in the permanent MCAO model. In an MRI-based study, initial infarct volume, as measured using DWI, was similar in the control and JPI-289-treated groups. However, infarct volume and brain swelling were significantly reduced in the group treated with JPI-289 (2 h) at 24 h and 7 days after MCAO. Neurological functions also improved in the group treated with JPI-289 (2 h) until 28 days after MCAO. Inhibition of PARP-1 has neuroprotective effects (reduction of infarct volume and brain swelling) in both tMCAO and pMCAO models of ischemic stroke.     

Propofol Protects Against Focal Cerebral Ischemia via Inhibition of Microglia-Mediated Proinflammatory Cytokines in a Rat Model of Experimental Stroke

Ischemic stroke induces microglial activation and release of proinflammatory cytokines, contributing to the expansion of brain injury and poor clinical outcome. Propofol has been shown to ameliorate neuronal injury in a number of experimental studies, but the precise mechanisms involved in its neuroprotective effects remain unclear. We tested the hypothesis that propofol confers neuroprotection against focal ischemia by inhibiting microglia-mediated inflammatory response in a rat model of ischemic stroke. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by 24 h of reperfusion. Propofol (50 mg/kg/h) or vehicle was infused intravenously at the onset of reperfusion for 30 minutes. In vehicle-treated rats, MCAO resulted in significant cerebral infarction, higher neurological deficit scores and decreased time on the rotarod compared with sham-operated rats. Propofol treatment reduced infarct volume and improved the neurological functions. In addition, molecular studies demonstrated that mRNA expression of microglial marker Cd68 and Emr1 was significantly increased, and mRNA and protein expressions of proinflammatory cytokines tumor necrosis factor-α, interleukin-1β and interleukin-6 were augmented in the peri-infarct cortical regions of vehicle-treated rats 24 h after MCAO. Immunohistochemical study revealed that number of total microglia and proportion of activated microglia in the peri-infarct cortical regions were markedly elevated. All of these findings were ameliorated in propofol-treated rats. Furthermore, vehicle-treated rats had higher plasma levels of interleukin-6 and C-reactive protein 24 h after MCAO, which were decreased after treatment with propofol. These results suggest that propofol protects against focal cerebral ischemia via inhibition of microglia-mediated proinflammatory cytokines. Propofol may be a promising therapeutic agent for the treatment of ischemic stroke and other neurodegenerative diseases associated with microglial activation.     

天麻酯溶性酚性成分对大鼠脑缺血/再灌注损伤的保护作用

为探讨天麻酯溶性酚性成分对大鼠脑缺血/再灌注的保护作用,本实验采用线栓法复制了大鼠局灶性脑缺血再灌注损伤模型,以神经学评分、脑梗塞体积、脑组织内水分含量、脑组织内钙调蛋白依赖性蛋白激酶(CaMKⅡ)表达作为评价指标,考察天麻酯溶性酚性成分的作用,结果表明天麻酯溶性酚性成分能够明显改善模型动物的神经病学症状,缩小脑梗塞体积,减轻脑水肿,调节CaMKⅡ的表达水平。说明天麻酯溶性酚性成分在防治大鼠脑缺血/再灌注损伤方面具有明显作用。