Down-regulated Na+/K+-ATPase activity in ischemic penumbra after focal cerebral ischemia/reperfusion in rats

This study was aimed to examine whether the Na⁺/K⁺ adenosine triphosphatase (Na⁺/K⁺-ATPase) activity in ischemic penumbra is associated with the pathogenesis of ischemia/reperfusion-induced brain injury. An experimental model of cerebral ischemia/reperfusion was made by transient middle cerebral artery occlusion (tMCAO) in rats and the changes of Na⁺/K⁺-ATPase activity in the ischemic penumbra was examined by Enzyme Assay Kit. Extensive infarction was observed in the frontal and parietal cortical and subcortical areas at 6 h, 24 h, 48 h, 3 d and 7 d after tMCAO. Enzyme Assay analyses revealed the activity of Na⁺/K⁺-ATPase was decreased in the ischemic penumbra of model rats after focal cerebral ischemia/reperfusion compared with sham-operated rats, and reduced to its minimum at 48 h, while the infarct volume was enlarged gradually. In addition, accompanied by increased brain water content, apoptosis-related bcl-2 and Bax proteins, apoptotic index and neurologic deficits Longa scores, but fluctuated the ratio of bcl-2/Bax. Correlation analysis showed that the infarct volume, apoptotic index, neurologic deficits Longa scores and brain water content were negatively related with Na⁺/K⁺-ATPase activity, while the ratio of bcl-2/Bax was positively related with Na⁺/K⁺-ATPase activity. Our results suggest that down-regulated Na⁺/K⁺-ATPase activity in ischemic penumbra might be involved in the pathogenesis of cerebral ischemia/reperfusion injury presumably through the imbalance ratio of bcl-2/Bax and neuronal apoptosis, and identify novel target for neuroprotective therapeutic intervention in cerebral ischemic disease.     

Cell-volume-dependent vascular smooth muscle contraction: role of Na+, K+, 2Cl− cotransport, intracellular Cl− and L-type Ca2+ channels

This study elucidates the role of cell volume in contractions of endothelium-denuded vascular smooth muscle rings (VSMR) from the rat aorta. We observed that hyposmotic swelling as well as hyper- and isosmotic shrinkage led to VSMR contractions. Swelling-induced contractions were accompanied by activation of Ca²⁺ influx and were abolished by nifedipine and verapamil. In contrast, contractions of shrunken cells were insensitive to the presence of L-type channel inhibitors and occurred in the absence of Ca²⁺_o. Thirty minutes preincubation with bumetanide, a potent Na⁺,K⁺,Cl^– cotransport (NKCC) inhibitor, decreased Cl^–_i content, nifedipine-sensitive ⁴⁵Ca uptake and contractions triggered by modest depolarization ([K⁺]_o=36 mM). Elevation of [K⁺]_o to 66 mM completely abolished the effect of bumetanide on these parameters. Bumetanide almost completely abrogated phenylephrine-induced contraction, partially suppressed contractions triggered by hyperosmotic shrinkage, but potentiated contractions of isosmotically shrunken VSMR. Our results suggest that bumetanide suppresses contraction of modestly depolarized cells via NKCC inhibition and Cl^–_i-mediated membrane hyperpolarization, whereas augmented contraction of isosmotically shrunken VSMR by bumetanide is a consequence of suppression of NKCC-mediated regulatory volume increase. The mechanism of bumetanide inhibition of contraction of phenylephrine-treated and hyperosmotically shrunken VSMR should be examined further.     

Pre-ischemic exercise reduces matrix metalloproteinase-9 expression and ameliorates blood-brain barrier dysfunction in stroke

Exercise reduces ischemia and reperfusion (I/R) injury in the rat stroke model. We investigated whether pre-ischemic exercise ameliorates blood-brain barrier (BBB) dysfunction in stroke by reducing matrix metalloproteinase (MMP)-9 expression and strengthening basal lamina. Adult male Sprague-Dawley rats were subjected to a 30 min exercise program on a treadmill 5 days a week for 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament in the exercised and non-exercised groups. Brain infarction was measured and neurological deficits were scored. BBB dysfunction was determined by examining brain edema and Evans Blue extravasation. Expression of collagen IV, the major component of basal lamina essential for maintenance of the endothelial permeability barrier, was quantitatively detected by Western blot and immunocytochemistry. Ex vivo techniques were used to compare collagen IV-labeled vessels in response to ischemic insult. Temporal relationship of expression of MMP-9 and its endogenous inhibitor, the tissue inhibitors of metalloproteinase-1 (TIMP-1), was determined by real-time PCR for mRNA and Western blot for protein during reperfusion. Brain edema and Evans Blue leakage were both significantly (P<0.01) reduced after stroke in the exercised group, in association with reduced brain infarct volume and neurological deficits. Western blot analysis indicated that exercise enhanced collagen IV expression and reduced the collagen loss after stroke. Immunocytochemistry demonstrated that collagen IV-labeled vessels were significantly (P<0.01) increased in exercised rats. In the ex vivo study, after exercised brains were incubated with ischemic brain tissue, a significantly (P<0.01) higher level of collagen IV-labeled vessels was observed as compared with non-exercised brains following the same treatment. The ex vivo study also revealed a key role of MMP-9 in exercise-strengthened collagen IV expression against I/R injury. TIMP-1 protein levels were significantly (P<0.01) increased by exercise. Our results indicate that pre-ischemic exercise reduces brain injury by improving BBB function and enhancing basal lamina integrity in stroke. This study suggests that the neuroprotective effect of physical exercise is associated with an imbalance of MMP-9 and TIMP-1 expression.     

吗啡预处理减轻脑中动脉阻塞所致小鼠缺血性脑损伤

目的探讨吗啡预处理(MP)对小鼠大脑中动脉阻塞(MCAO)所致缺血性脑损伤的影响及其可能机制。方法复制小鼠MCAO模型,用2,3,5-氯化三苯基四氮唑(TTC)染色、神经行为学评分和Western blot等,观察小鼠行为学变化、脑梗死面积、脑水肿率,以及sham组左侧皮质组织,MCAO组和MP组脑梗死核心区、半影区及对侧皮质组织热休克蛋白70(Hsp70)蛋白表达量。结果 MCAO组小鼠脑梗死面积为31.69%±4.19%,脑水肿率为8.98%±1.79%,MP可明显降低MCAO所致的脑梗死面积及水肿率,分别为23.34%±4.85%和4.60%±0.86%(P<0.05),同时明显改善小鼠神经行为缺陷评分(P<0.05)。MCAO组皮质梗死核心区、半影区及对侧皮质Hsp70蛋白表达水平高于sham组(P<0.05),MP组半影区Hsp70蛋白表达水平较MCAO组进一步显著升高(P<0.05)。结论吗啡预处理降低小鼠脑中动脉阻塞所致缺血性脑损伤,半影区Hsp70蛋白水平的高表达可能参与了这种保护作用。     

Role of CD11b+Gr-1+ myeloid cells in AGEs-induced myocardial injury in a mice model of acute myocardial infarction

Aims: Polymorph neutrophils are the predominant inflammatory cells and play a crucial role on the pathogenesis of myocardial injury at the early stage of acute myocardial infarction (AMI). However, the precursors and the differentiation of neutrophils are not fully understood. Here we explored the role of CD11b⁺Gr-1⁺ myeloid-derived suppressor cells (MDSCs) on myocardial injury in the absence and presence of advanced glycation end-products (AGEs) in a mice model of AMI. Methods and Results: Male C57BL/6J mice were selected. Fluorescent actived cell sortor (FACS) data demonstrated significantly increased CD11b⁺Gr-1⁺ MDSCs both in peripheral blood circulation and in the ischemic myocardium at 24 hours post AMI. Quantitative-real-time PCR results also revealed significantly upregulated CD11b and Ly6G mRNA expression in the ischemic myocardium. AGEs treatment further aggravated these changes in AMI mice but not in sham mice. Moreover, AGEs treatment also significantly increased infarction size and enhanced cardiomyocyte apoptosis. The mRNA expression of pro-inflammatory cytokine IL-6 and iNOS2 was also significantly increased in AMI + AGEs group compared to AMI group. Conclusion: These data suggest enhanced infiltration of MDSCs by AGEs contributes to aggravated myocardial injury in AMI mice, which might be one of the mechanisms responsible for severer myocardial injury in AMI patients complicating diabetes.     

NKCC1和KCC2在成年大鼠大脑皮质神经元的胞体和树突的不同表达(英文)

γ-氨基丁酸(GABA)是成年哺乳动物脑内主要的抑制性神经递质,但电生理的研究表明,GABA在成熟皮质神经元的树突部位可以产生兴奋性作用,但该现象的形态学基础,目前尚不清楚。GABA产生兴奋性作用的关键主要依赖于神经元胞内的氯离子浓度,其中Na+-K+-Cl-共转运体1(NKCC1)促进细胞内Cl-堆积,而K+-Cl-共转运体2(KCC2)则外排胞内的Cl-,降低胞内的Cl-浓度。本研究应用免疫荧光组织化学双重标记结合荧光强度分析,检测NKCC1和KCC2在成年大鼠脑皮质和培养的大鼠脑皮质神经元树突和胞体的表达和分布情况。结果显示:成年大鼠皮质神经元的胞浆和细胞膜均有NKCC1的表达,而KCC2主要表达在神经元胞体和树突膜上,其中NKCC1在神经元树突上的表达水平比胞体高,而KCC2的表达水平在树突和胞体膜上没有明显差异。皮质神经元经培养20d后,NKCC1和KCC2在树突和胞体的表达模式与在体的分布相类似。本研究结果提示,NKCC1在大鼠皮质神经元树突的表达较多,可能是GABA兴奋神经元树突的原因。     

局部亚低温对大鼠局灶性脑缺血-再灌注模型NKCC1 mRNA水平的影响

目的:观察局部亚低温对大鼠局灶性脑缺血-再灌注模型NKCC1 mRNA表达水平的影响,探索局部亚低温的脑保护机制.方法:雄性Wistar大鼠50只,随机分成常温组和亚低温组.应用"线栓法"实现大鼠右侧大脑中动脉阻塞,2h后拔出线栓进行再灌注,于再灌注3h、12h、24h和72h处死大鼠.应用RT-PCR方法观察NKCC1 mRNA水平的变化.结果:与假手术亚组相比,缺血-再灌注亚组大鼠缺血区皮质NKCC1 mRNA水平明显升高,开始于再灌注3h,12h～24h达到高峰,72h开始下降,亚低温组各再灌注时间点NKCC1 mRNA水平均低于常温组中相应亚组的水平.结论:局部亚低温通过抑制缺血-再灌注过程中NKCC1 mRNA水平的上调发挥脑保护作用.     

人参皂苷Rb1对大鼠脑缺血再灌注损伤中NAIP表达的影响

目的:观察人参皂苷Rb1对神经元凋亡抑制蛋白(neuronal apoptosis inhibitory protein,NAIP)在脑缺血再灌注损伤中表达的影响,探讨人参皂苷Rb1对缺血性脑病的防治机制.方法:线栓法阻断大鼠大脑中动脉2 h,再灌注3 h～5 d制备脑缺血再灌注模型,应用免疫组织化学方法标记NAIP阳性细胞,观察人参皂苷Rb1对NAIP阳性细胞数的影响.结果:缺血再灌注后,缺血半暗带内的NAIP阳性细胞表达增加,海马CA 1区等部位的NAIP阳性细胞数量也明显增加,而缺血中心区无NAIP阳性细胞的表达.实验对照组中NAIP阳性细胞数量随再灌注时间延长逐渐升高,12 h达到高峰,至5 d时NAIP阳性细胞数量表达低于正常水平.实验用药组中NAIP阳性细胞数量在2 d时达到高峰,且其高峰值明显高于实验对照组中的高峰值,后随再灌注时间的延长而逐渐下降,至5 d时仍处于较高水平.结论:脑缺血再灌注后,NAIP表达增加是脑组织对损伤的一种保护性反应,其对缺血区周围的神经细胞的保护作用更为明显.NAIP在脑组织中的表达具有一定的时间规律性,并且人参皂苷Rb1可能通过上调NAIP的表达发挥对受损脑组织的保护作用.     

高压氧预处理通过HIF-1α/VEGF通路减轻大脑缺血再灌注损伤

目的:探讨缺氧诱导因子1α(HIF-1α)/血管内皮生长因子(VEGF)通路在高压氧(HO)预处理减轻缺血再灌注(IR)模型大鼠大脑损伤过程中的作用。方法:选择SPF级健康雄性成年SD大鼠32只,使用随机数字软件将其分为对照组(control组)、IR组、HO-IR组和HO-IR-HIF-1α抑制剂组(HO-IR-I组)。IR模型通过大脑中动脉栓塞法制作,对照组仅分离暴露相应血管。HO-IR组和HO-IR-I组大鼠均在制模前在动物高压舱内进行HO治疗4周(每天1次);HO-IR-I组每天在HO预处理前,经腹腔注射4 mg/kg的HIF-1α抑制剂YC-1[3-(5’-hydroxymethyl-2’-furyl)-1-benzylindazol]。在制作模型第1天和第7天行神经行为学评估,第7天观察结束后麻醉处死大鼠,取脑组织测量梗死体积,Western blot检测HIF-1α/VEGF通路相关蛋白及凋亡相关蛋白Bax和Bcl-2的水平,TUNEL法检测凋亡细胞数。结果:与control组比较,IR组、HO-IR组和HO-IR-I组大鼠的神经功能评分降低,脑梗死体积比例及HIF-1α、VEGF、Bax和Bcl-2的蛋白表达均增加,凋亡细胞数量亦增加(P0.05);与IR组比较;HO-IR组和HO-IR-I组的神经功能评分升高,HIF-1α、VEGF和抑凋亡蛋白Bcl-2表达上调,脑梗死体积比例降低,促凋亡蛋白Bax表达下调,凋亡细胞数量减少(P0.05);与HO-IR组比较,HO-IR-I组的神经功能评分降低,HIF-1α、VEGF和抑凋亡蛋白Bcl-2表达下调,脑梗死体积比例升高,促凋亡蛋白Bax表达上调,凋亡细胞数量增加(P0.05)。结论:HO预处理减轻大脑IR损伤的机制可能与通过诱导HIF-1α/VEGF通路调节凋亡进程有关。     

甲基莲心碱对脑缺血再灌注脑损伤的调节作用

目的探讨甲基莲心碱(Neferine,Nef)对缺血再灌注脑损伤大鼠脑保护作用及其机制.方法线栓法建立大鼠脑缺血再灌注损伤(CI/R)模型.造模后对大鼠神经功能进行评分;HE检测病理损伤;检测血清MDA、SOD和LDH含量;TUNEL检测脑细胞凋亡;RT-PCR检测Caspase-3、-9 mRNA表达;免疫组化检测脑组织ICAM-1表达;ELISA检测IL-6、IL-18和IL-1β的含量;蛋白印迹检测TLR4、NF-κB P65(核)和MIP-2表达.结果甲基莲心碱能有效改善脑缺血再灌注损伤大鼠的神经功能(P<0.01),减少造模诱导的脑组织病理损伤;减少MDA和LDH含量(P<0.01),增加SOD活性(P<0.01);减少脑组织细胞凋亡率(P<0.01),下调凋亡相关蛋白Caspase-3、-9 mRNA表达水平(P<0.01);降低促炎因子(ICAM-1)、炎性因子(IL-6,IL-18,IL-1β)和炎性蛋白(TLR4,NF-κB P65,MIP-2)在脑组织中的表达水平(P<0.01).结论甲基莲心碱能对脑缺血再灌注损伤大鼠脑组织起保护作用,其机制与减少凋亡及抑制炎性反应有关.     

KGFR promotes Na+ channel expression in a rat acute lung injury model

Background

Binding of keratinocyte growth factor (KGF) to the KGF receptor (KGFR) plays an important role in the recovery of alveolar epithelial cells from acute lung injury (ALI).

Objectives

To evaluate the effect of gene therapy via adenovirus gene transfer of KGFR on the treatment of ALI.

Methods

Sprague-Dawley rats were divided into four groups: normal controls, injury controls, normal adenovirus transduced group and injury adenovirus transduced group. The ALI model was induced by lipopolysaccharide (LPS) injection. Recombinant adenovirus (AdEasy-KGFR) was injected via the tail vein. Expression of the sodium (Na⁺) channel in rat alveolar type II (ATII) epithelial cells was determined by PCR, immunohistochemistry and immunoelectron microscopy of rat lung tissues.

Results

Gene expression of the Na⁺ channel and KGFR in ATII cells was higher in the normal adenovirus transduced group than the three other groups; expression of these two genes in the injury adenovirus transduced group was higher than the injury control group. Na⁺ channel protein expression was lower in the injury adenovirus transduced group but higher than the injury control group.

Conclusions

KGFR over-expression induced Na channel expression could potentially be beneficial for ALI therapy.     

GAD67-GFP基因敲入小鼠黑质网状部神经元GABA与氯离子转运体KCC2和NKCC1的共存

为了观察谷氨酸脱羧酶67-绿色荧光蛋白(GAD67-GFP)基因敲入小鼠黑质网状部(SNr)内,表达GFP的GABA能神经元与一对功能相反的Cl-共转运体(K+-Cl-cotransporter2,KCC2;Na+-K+-Cl-cotransporter1,NKCC1)的共存情况,本研究分别运用原位分子杂交与免疫组织化学相结合以及GFP与KCC2或NKCC1免疫荧光染色相结合的双重标记方法,在光学显微镜和激光共聚焦显微镜下同时进行观察。结果显示:(1)SNr内95%以上的GFP阳性神经元同时表达KCC2 mRNA,而50%表达KCC2 mRNA的阳性神经元呈GFP阳性;(2)SNr内80%以上的GFP阳性神经元同时表达NKCC1 mRNA,约35%表达NKCC1 mRNA的阳性神经元呈GFP阳性;(3)SNr内90%以上的GFP阳性神经元同时表达KCC2,双标神经元约占KCC2阳性神经元的50.5%;(4)SNr内80.5%以上的GFP阳性神经元同时表达NKCC1,双标神经元约占NKCC1阳性神经元的42.5%。以上结果表明,SNr内表达GFP的GABA能神经元大部分与KCC2和NKCC1共存,提示氯离子共转运体可能对SNr内GABA能神经元起重要的调控作用。     

大黄素甲醚对大鼠脑缺血再灌注损伤的拮抗作用

目的：探讨大黄素甲醚对脑缺血再灌注后IL-1β含量和ICAM-1及caspase-3表达的影响。 方法： 91只SD大鼠随机分为正常组（normal），假手术组（sham），模型组（model），大黄素甲醚大剂量（PHD）及小剂量(PLD)组。采用线栓法复制大鼠右侧大脑中动脉脑缺血再灌注模型，用放射免疫法测定病变侧脑组织IL-1β的含量，用免疫组织化学方法测定ICAM-1和caspase-3表达的变化，并进行组织病理学观察。 结果： Model组再灌注6 h病变侧IL-1β含量明显升高且达高峰，再灌注24 h病变侧ICAM-1、caspase-3表达明显升高，中性粒细胞附壁浸润明显；大黄素甲醚PHD组再灌注12 h、24 h病变侧IL-1β、ICAM-1和caspase-3表达明显低于model组相应时段(P<0.05或P<0.01)，中性粒细胞附壁浸润较少。 结论： 大黄素甲醚可降低脑缺血再灌注后IL-1β、ICAM-1和caspase-3水平，减轻脑缺血再灌注损伤。     

NAD(+) administration decreases ischemic brain damage partially by blocking autophagy in a mouse model of brain ischemia

Nicotinamide adenine dinuleotide (NAD(+)) plays critical roles in multiple biological functions. Previous studies have indicated that NAD(+) treatment decreases oxidative stress-induced death of primary neurons and astrocytes. Intranasal administration of NAD(+) also reduces brain damage in a rat model of transient focal brain ischemia. However, the mechanisms underlying this protective effect remain unknown. In this study, we used a mouse model of brain ischemia to test our hypothesis that NAD(+) decreases ischemic brain damage partially by preventing autophagy. Adult male mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 90min, and NAD(+) was administered intraperitoneally (i.p.) immediately after reperfusion started. We found that administration with 50mg/kg NAD(+) led to significant decreases in infarct size, edema formation, and neurological deficits at 48h after ischemia. NAD(+) administration also significantly decreased brain ischemia-induced autophagy in the cortex and hippocampus. We further found that prevention of autophagy by 3-methyladenine (3-MA), a selective autophagy inhibitor, significantly reduced ischemic brain damage, suggesting an important role of autophagy in the ischemic brain injury in our animal model. Collectively, our findings have suggested that NAD(+) administration decreases ischemic brain damage at least partially by blocking autophagy. This is the first suggested mechanism regarding the protective effects of NAD(+) in cerebral ischemia, which further highlights the promise of NAD(+) for treating brain ischemia.     

川芎嗪对大鼠脑缺血再灌注损伤后大脑皮质Bc1-2表达的影响

目的:研究川芎嗪对大鼠脑缺血再灌注损伤后Bcl-2表达的影响.方法:以线栓法制作大鼠大脑中动脉阻塞的局灶性脑缺血再灌注模型,采用免疫印迹、2, 3, 5-氯化三苯四氮唑(TTC)、 H-E染色和神经行为相结合的方法,观测缺血再灌注侧大脑皮质内Bcl-2的表达、脑梗塞体积、脑组织结构及神经功能的变化.结果:与缺血再灌注组(I 2h/R24h)比较,川芎嗪组的Bcl-2表达明显增高,脑梗塞体明显缩小,脑组织的病理损伤和神经异常行为明显减轻.结论:川芎嗪可通过上调Bcl-2的表达,缩小脑梗塞的体积和减轻脑缺血区组织结构的损伤以及明显改善神经症状,对脑缺血再灌注损伤有保护作用.     

Effect of Na+,K+,2Cl- Cotransport Inhibitor Bumetanide on Electrical and Contractile Activity of Smooth Muscle Cells in Guinea Pig Ureter

The effect of Na⁺,K⁺,2Cl^- cotransport inhibitor bumetanide on action potentials and contractions of smooth muscle cells in the ureter of guinea pigs evoked by electrical stimulation was studied by the method of double sucrose bridge. Bumetanide (10-100 M) dose-dependently suppressed action potential and contractions of smooth muscle cells induced by 1-10 M histamine, 10 M mesatone, 5 mM tetraethylammonium, and 100 M sodium nitroprusside. Our findings suggest that test substances modulate Na⁺,K⁺,2Cl^- cotransport in smooth muscle cells.     

他米巴罗汀减轻大鼠脑缺血再灌注损伤

目的探讨他米巴罗汀(Am80)对大鼠脑缺血再灌注损伤(CIR)的作用。方法将大鼠随机分为:假手术组(sham)、模型组(I/R)和他米巴罗汀干预组(Am80,灌胃给予Am80 6 mg/kg)。采用线栓法建立大脑中动脉栓塞(MCAO)模型。术后24 h断头取脑,在处死前采用双盲法进行神经行为学评分;TTC染色测定脑梗死体积;Western blot和RT-q PCR法分别检测RARα、Bcl-2和Bax蛋白及mRNA的表达。结果 Am80可显著改善MCAO大鼠神经功能缺损,有效地降低脑梗死体积(P0.01),上调RARα和Bcl-2表达(P0.01),降低Bax的表达(P0.01)。结论他米巴罗汀对脑缺血再灌注损伤大鼠有保护作用,其作用可能与抗凋亡有关。     

高血脂大鼠脑缺血再灌注损伤后Bcl-2和Bax的表达变化及灯盏乙素的影响

目的 观察高血脂大鼠缺血侧大脑皮质额叶内B淋巴细胞瘤-2（Bcl-2）、Bcl-2相关X蛋白（Bax）的表达变化,探讨灯盏乙素对高血脂大鼠脑缺血再灌注损伤的保护作用。 方法 大鼠建立高血脂模型后,线栓法阻塞大脑中动脉建立脑缺血再灌注损伤模型,HE染色观察大脑皮质额叶的病理变化,免疫组织化学和免疫印迹法观察Bcl-2、Bax蛋白的表达变化,同时结合神经行为学评分和2,3,5-氯化三苯基四氮唑（TTC）染色观察大鼠的神经行为及脑梗死灶体积的变化。 结果 与假手术组相比,生理盐水组大鼠脑组织损伤加重,Bcl-2的表达明显减少,Bax的表达明显增高,同时大鼠的神经行为学评分和脑组织梗死灶体积明显增加（P<0.05）。与生理盐水组相比,灯盏乙素治疗组脑组织损伤减轻,Bcl-2的表达明显增多,Bax的表达明显减少,同时大鼠的神经行为学评分和脑组织梗死灶体积明显降低（P<0.05）。 结论 灯盏乙素对高血脂大鼠脑缺血再灌注损伤的保护作用可能是通过促进Bcl-2的表达,抑制Bax的表达实现的。     

SIRT1对早期脑缺血大鼠水通道蛋白4表达的影响

目的:检测水通道蛋白4(AQP4)及沉默信息调节因子1(SIRT1)在脑缺血大鼠脑组织中的表达变化,探究SIRT1对AQP4的调节作用,明确二者在脑缺血及脑水肿发生发展中的作用。方法:雄性SD大鼠随机分成假手术组(sham组)和脑缺血模型组(MCAO组),其中MCAO组又分为6 h、12 h、24 h和48 h 4个时点组别。采用线栓法阻塞大脑中动脉建立局灶性脑缺血模型,于相应时点进行神经症状评分,Morris水迷宫检测大鼠学习认知功能,TTC染色观察脑梗死体积,干湿重法检测脑含水量的变化,HE染色观察大脑皮层周围组织神经细胞形态学变化,Western blot检测AQP4、SIRT1和基质金属蛋白酶9(MMP-9)的表达情况。结果:与sham组相比较,随着再灌注时间增加,MCAO组大鼠神经功能评分、脑梗死体积、脑组织通透性和脑组织含水量均持续增加,而大鼠学习认知功能则降低显著,HE染色显示脑缺血大脑皮层周围组织神经元细胞形态不规则,数目减少;Western blot实验结果显示AQP4表达水平呈增高趋势,SIRT1表达降低,MMP-9表达增高,MCAO-48 h组与sham组比较差异最明显(P0.01)。结论:脑缺血后,伴随脑组织损伤的加剧,SIRT1和MMP-9信号通路的表达激活影响了AQP4的表达活化,共同参与了脑水肿的形成。     

局灶性脑梗死出血转化模型中基质金属蛋白酶9的表达

背景：理论上来说,出血性转化可发生于任何脑梗死患者,可见于脑梗死自然演变病程的任何阶段。因此进一步从缺血时间和再灌注角度进行梗死后出血转化发病机制研究可以为临床预防和治疗梗死后出血转化提供理论依据。 目的：观察持续性脑梗死与脑缺血再灌注大鼠脑组织基质金属蛋白酶9的表达。 方法：将健康雄性成年Wistar大鼠随机分为3组：即假手术组、缺血再灌注组、持续脑梗死组。采用线栓法制成大脑中动脉闭塞模型,缺血再灌注组在相应缺血时间点(4.5,6,12,24,48 h)将线栓拔出再灌注24 h,假手术组手术过程同缺血再灌注组,但未置入栓线。持续脑梗死组制成大脑中动脉闭塞模型,但中间不取出栓线。分别于术后2 h进行模型成功评价,并于术后相应时间点进行神经功能障碍评分;TTC染色观察脑组织发生出血转化情况;用免疫组化方法测定基质金属蛋白酶9的表达。 结果与结论：脑梗死后4.5 h内血流再通神经功能评分明显提高,6 h以后尤其12 h以后血流再通将加重神经功能缺损;在缺血再灌注组内随着缺血时间的延长神经功能评分逐渐降低,缺血48 h降至最低。脑组织TTC染色可见缺血12,24,48 h再灌注大鼠均有不同程度的出血转化发生。基质金属蛋白酶9以负性因素参与再灌注损伤和出血性转化,加重缺血再灌注损伤以及促进出血性转化发病。 中国组织工程研究杂志出版内容重点：肾移植;肝移植;移植;心脏移植;组织移植;皮肤移植;皮瓣移植;血管移植;器官移植;组织工程