The Effect of Ovariectomy and Estrogen on Penetrating Brain Arterioles and Blood‐Brain Barrier Permeability

Objective : We investigated the effect of estrogen replacement on the structure and function of penetrating brain arterioles (PA) and blood‐brain barrier (BBB) permeability. Materials and Methods : Female ovariectomized Sprague‐Dawley rats were replaced with estradiol (E₂) and estriol (E₃) (OVX + E;N=13) and compared to ovariectomized animals without replacement (OVX; N=14) and intact controls (CTL, proestrous; N=13). Passive and active diameters, percent tone, and passive distensibility of pressurized PA were compared. In addition, BBB permeability to Lucifer Yellow, a marker of transcellular transport, was compared in cerebral arteries. Results : Ovariectomy increased myogenic tone in PA, compared to CTL, that was not ameliorated by estrogen treatment. Percent tone at 75 mmHg for CTL vs. OVX and OVX + E was 44±3% vs. 51±1% and 54±3% (P<0.01 vs. CTL for both). No differences were found in passive diameters or distensibility between the groups. BBB permeability increased 500% in OVX vs. CTL animals; however, estrogen replacement restored barrier properties: flux of Lucifer Yellow for CTL, OVX, and OVX + E was (ng/mL): 3.4±1.2, 20.2±5.3 (P<0.01 vs. CTL), and 6.15±1.2 (n.s.). Conclusions : These results suggest that estrogen replacement may not be beneficial for small‐vessel disease in the brain, but may limit BBB disruption and edema under conditions that cause it.     

补阳还五汤对脑缺血再灌注后星形胶质细胞及热休克蛋白的影响

目的探讨补阳还五汤对脑缺血再灌注后星形胶质细胞(AS)及热休克蛋白(HSP70)的影响.方法采用沙土鼠双侧颈动脉夹闭脑缺血模型,于脑缺血15min再灌注24 h和48 h后,运用免疫组化技术观察星形胶质纤维酸性蛋白(GFAP)及热休克蛋白70的蛋白基因表达.结果缺血再灌注24 h后,GFAP免疫阳性反应达高峰,补阳还五汤可使GFAP免疫反应减轻;缺血再灌注48 h后GFAP表达减弱,补阳还五汤可使其增强;缺血再灌注后48 h,HSP70 mRNA及蛋白表达明显增强,补阳还五汤可明显抑制其转录外,还可轻度降低HSP70的翻译.结论补阳还五汤对脑缺血损伤后神经功能的保护作用可能与调节星形胶质细胞及抑制缺血脑损伤HSP70基因的过度表达作用有关.     

Caspase-9 Inhibition after Focal Cerebral Ischemia Improves Outcome following Reversible Focal Ischemia

Cerebral ischemia initiates a program of cell death known as apoptosis. Early steps in these death promoting events are the release of cytochrome c from the mitochondria and activation of caspase-9. The purpose of this report is to determine if the administration of a specific caspase-9 inhibitor, Z-Leu-Glu(Ome)-His-Asp(Ome)-FMK·TFA (Z-LEHD-FMK) would attenuate apoptosis and the resultant brain injury after ischemia. Adult Wistar rats underwent 3 h of temporary middle cerebral artery occlusion (MCAO) followed by 24 h of reperfusion. An intraventricular injection of 4.8 g of Z-LEHD-FMK was given 15-min postreperfusion. Administration of the caspase-9 inhibitor, Z-LEHD-FMK, to the experimental group (n = 12) reduced total infarction volume by 49% (p < 0.05) and improved neurological outcome by 63% (p < 0.01) as compared to the control group (n = 12). Western blot analysis of animals that underwent ischemia-reperfusion showed the appearance of the active form of caspase-9. Inhibition of caspase-9, the apical caspase in cytochrome-c-dependent apoptosis, is an effective intervention to attenuate neurological injury after focal ischemia.     

局灶性脑缺血再灌注损伤模型大鼠的代谢组学研究

目的 利用基于硅烷基衍生化反应的气相色谱-质谱联用技术(GC-MS)的代谢组学测定方法,获得局灶性脑缺血再灌注损伤大鼠的血浆代谢物指纹图谱,初步揭示局灶性脑缺血再灌注损伤的生物标志物,为脑缺血药物筛选提供新的方法.方法 通过硅烷基化反应,将生物样品中的氨基酸、脂肪酸、有机酸、糖类和固醇类物质制成热稳定性强、易挥发的硅烷酯或醚,通过优化色谱条件对大鼠血浆中内源性代谢物进行分析测定.结果 利用已建立的GC-MS测定方法,获得了大鼠血浆代谢物指纹图谱,并鉴定了其中29个主要色谱共有峰,并通过主成分分析方法 比较正常和模型组的指纹图谱差异.结论 通过正常组和模型组大鼠血浆代谢物指纹图谱的比较分析,发现与脑缺血相关的生物标志物.     

高血压对局部脑缺血及缺血后再灌流梗塞灶的影响

目的观察脑缺血后再灌流对脑梗塞灶的影响。方法用氯化三苯四氮唑（ＴＴＣ）染色技术结合电子计算机图像分析系统定量测定肾血管性高血压大鼠（ＲＨＲ）和ＳＤ大鼠（ＳＤＲ）局部脑缺血及脑缺血后再灌流梗塞灶体积。结果发现持续缺血组及缺血后再灌流组ＲＨＲ的梗塞体积分别为２１８．７３±３１．１２ｍｍ３和２０１．２９±３３．７１ｍｍ３而ＳＤＲ持续缺血组及缺血后再灌流组分别为１３１．６１±２０．８８ｍｍ３和１１９．４０±２７．１４ｍｍ３，ＲＨＲ和ＳＤＲ梗塞体积均存在显著差异。结论长期慢性高血压引起的脑侧支循环障碍对脑缺血及缺血后再灌流梗塞灶有重要影响。     

脑缺血再灌注后影响血脑屏障通透性的因素

血脑屏障通透性增高是造成血管源性脑水肿和炎症反应等病理学变化的主要环节。近年来,许多研究表明,在脑缺血再灌注过程中有多种介质参与了血脑屏障结构和功能的改变和破坏。     

脑心通胶囊对大鼠局灶性脑缺血再灌注损伤及MMP-2、MMP-9表达的影响

目的观察脑心通胶囊对大鼠局灶性脑缺血再灌注脑组织病理变化及MMP-2、MMP-9表达的影响，并探讨其可能的保护机制。方法建立大鼠大脑中动脉缺血再灌注模型，应用HE及S-P免疫组化法分别观察模型组及用药组大鼠全脑组织的病理改变及MMP-2、MMP-9表达的变化。结果假手术组大鼠脑组织形态结构正常，MMP-2、MMP-9见少量散在阳性表达或不表达；模型组大鼠大脑缺血再灌注区组织明显水肿、蜕变、坏死伴少量炎细胞浸润，对大脑相应区及双侧小脑轻度水肿，MMP-2、MMP-9表达较假手术组对应区显著升高（P〈0．01或P〈0．05），其中缺血侧大脑以坏死区边缘脑组织表达为甚，且较对侧大脑及双侧小脑明显升高（P〈0．05）；脑心通用药组大鼠大脑缺血区组织水肿、蜕变、坏死较模型组明显减轻，对侧大脑相应区及双侧小脑脑组织形态结构正常，MMP-2、MMP-9表达较模型组对应区显著降低（P〈0．05）。结论脑心通胶囊对大鼠局灶性脑缺血再灌注后包括病灶在内的全脑损伤有保护作用，其作用机制可能与降低MMP-2、MMP-9表达有关。     

Ischemic Cell Death: Dynamics of Delayed Secondary Energy Failure During Reperfusion Following Focal Ischemia

Reperfusion injury is believed to contribute to the pathophysiology of ischemic cell death, but the precipitating factors have yet to be completely elucidated. The goal of this study was to examine if reflow-induced secondary energy failure is a component in the events that lead to cell death following increasing periods of middle cerebral artery (MCA) occlusion in Wistar rats. Discrete sections within the MCA distribution were dissected and analyzed for high-energy phosphates and glucose. Regional cerebral blood flow was determined by [¹⁴C]-iodoantipyrine technique in representative groups. The levels of ATP + P-creatine were initially depressed at the end of the focal ischemia and the concentrations in the penumbra were unchanged for up to 8 h after 2 h of ischemia which contrasts with response in the ischemic core, striatum, and penumbra where the HEP generally recovered to values near those of control only to decrease with increasing periods of reflow. The possibility of a rebound ischemia in secondary energy failure (SEF) was precluded by regional CBF values and concentrations of glucose that were significantly higher than the threshold for an ischemic effect. The depletion of cellular energy stores following SEF strongly indicates that the evolution of infarct during reflow results from loss of ATP and its synthesis.     

E-选择素与脑缺血再灌注损伤

E-选择素为可诱导性黏附分子，与脑缺血再灌注损伤时的多种因子相关。文章主要综述了E-选择素在脑缺血再灌注损伤中与细胞间黏附分子-1、肿瘤坏死因子-α、NF-kB和白细胞功能相关抗原-1的关系，以期为E-选择素在预防、诊断和治疗缺血性脑血管病方面提供帮助。     

细胞凋亡与心肌缺血/再灌注损伤

近年研究发现细胞凋亡与心肌缺血/再灌注损伤关系密切,可能是其发病机制之一。现就心肌缺血/再灌注损伤中细胞凋亡发生的原因、参与调控的相关基因及信号途径作一综述。     

心肌缺血再灌注损伤机制的研究近况

随着"缺血再灌注损伤"这个概念提出以来,缺血再灌注损伤的机制越来越受到关注,本文就缺血再灌注损伤机制的研究近况进行了综述.     

大鼠局灶脑缺血/再灌注后海马CA1区NF-κB与HSP70的表达与预刺激小脑顶核的作用

目的　研究大鼠局灶性脑缺血后海马 CA1区 NF- κB及 HSP70的表达及预防性电刺激小脑顶核 (FNS)的作用。方法　线栓法制备大鼠局灶性脑缺血模型 ,分别预刺激小脑齿状核与小脑顶核 ,取脑作病理切片 ,用 HE染色、尼氏染色、免疫组化与 TUNEL原位染色的方法 ,通过图象分析测定缺血侧海马 CA1区死亡神经细胞数目以及尼氏染色阳性细胞、NF- κBP65与 HSP70免疫反应阳性细胞 ,分析 FNS的治疗作用及可能机制并与小脑齿状核比较。结果　 FNS可使海马 CA1区死亡神经细胞数目减少 ,凋亡减轻 ,NF-κBP65阳性细胞光密度降低 ,尼氏染色与HSP70免疫反应阳性细胞光密度增高 ,预刺激小脑齿状核无此作用。结论　 FNS能减轻海马区神经细胞坏死与凋亡 ,促进 HSP70的表达 ,抑制 NF-κB的表达 ,预刺激小脑顶核有抑制海马区炎症因子的作用 ,并可能通过这一作用而改善大鼠脑缺血损伤     

自噬在心肌缺血再灌注中作用的研究进展

自噬是指细胞内的自身物质被溶酶体所降解的过程,为普遍存在的生命现象,是细胞处于饥饿状态时的一种自我保护机制。既往研究表明,在心肌缺血再灌注过程中,自噬被诱导激活,自噬体明显增多。自噬在缺血再灌注中的作用表现出双面性,缺血期主要发挥保护作用,但再灌注时期自噬过度激活则表现出损伤作用,可导致自噬性细胞死亡。自噬具体是如何被激活,怎样发挥其影响作用,至今尚无清楚的答案。本文就自噬在心肌缺血再灌注中作用的研究进展进行综述。     

Integrins and regulation of the microcirculation: from arterioles to molecular studies using atomic force microscopy

Integrins are an important class of receptors for extracellular matrix proteins that can mediate both force transmission, by virtue of their connections with the cell matrix and cytoskeleton; and signal transduction, resulting from the assemblages of signaling proteins that associate with focal contacts. Consequently, integrins have been proposed to be the mechanosensor in vascular smooth muscle and endothelial cells and to play a central role in mechanotransduction. In this regard, mechanical force is an important stimulus for many vascular functions, including contractile and relaxation processes,proliferation, migration, attachment, and cell phenotype determination. Collectively, these functions define physiological properties of the vasculature such as control of blood flow, capillary pressure,permeability, and peripheral vascular resistance, and play a role in pathophysiological processes like hypertension, diabetes, and arteriosclerosis. Our knowledge concerning how integrins sense and transduce physical forces into cellular signals and which integrins are involved is incomplete. Compared to other cell surface receptors, integrins have a relatively low affinity for their binding sites on the extracellular matrix and their affinity can be regulated. These characteristics of integrin-ligand interaction may facilitate dynamic processes such as cell migration, cell remodeling, and contractile activation in response to external forces. Important questions remain concerning the nature and origin of integrin-mediated signaling in the vascular wall.     

Energy Metabolism and NAD-NADH Redox State in Brain Slices in Response to Glutamate Exposure and Ischemia

A comparative study of the effects of excitotoxic levels of glutamate with ischemia on the cerebral energy metabolism and [NAD]/[NADH] ratio was carried out in adult rat brain slices. Glutamate moderately decreased the high energy phosphates and intracellular pH whereas ischemia showed a pronounced decrease in the high energy phosphates and intracellular pH. The [NAD]/[NADH] ratio increased continuously during glutamate exposure whereas an initial reduction and subsequent oxidation occurred during ischemia. Uptake of glutamate prevailed throughout the glutamate exposure to brain slices signifying favorable glial energy levels while efflux occurred during ischemia indicating complete neuronal and glial depolarization. A net synthesis of glutamate was also observed during ischemia. A small but significant increase in lactate may be a result of increased glycolysis during glutamate exposure, on the other hand a large increase in lactate during ischemia suggests a total failure of oxidative metabolism. Our results show that glutamate exposure to brain slices causes a mild energetic stress and an increase in [NAD]/[NADH] ratio whereas predominant inhibition of phosphate metabolites and dual effect on NAD/NADH redox state was observed during ischemia. It is suggested that the NAD/NADH redox state together with phosphate metabolites and intracellular pH of the periinfarct region could provide vital evidence about the possible involvement of glutamate.     

脑钠素与肌钙蛋白和C反应蛋白在心肌缺血和心力衰竭患者中的比较

生化标记物脑钠素(BNP)升高反映心室负荷增加,BNP主要由心室肌分泌.近年来许多试验显示BNP在心肌缺血和心力衰竭研究领域具有出色的诊断、预后及监测价值.另外,反映心肌坏死的肌钙蛋白和炎症标志物C反应蛋白(CRP)对于心肌缺血和心力衰竭的评判也有独到之处.重要的是BNP、肌钙蛋白和CRP代表不同的病理生理机制,因此有必要在同一试验人群中对三者进行比较研究,以便提供更多的检验信息,更好地指导临床实践.     

中医药抗脑缺血再灌注细胞凋亡研究进展

综述近十年中医药抗脑缺血再灌注后神经细胞凋亡的研究，主要从中医药对神经细胞凋亡调控基因和蛋白表迭的影响方面进行阐述。