血液光量子疗法对局灶性脑缺血大鼠大脑皮层局部血流量和脑水肿的影响

本文动态观测了光量子疗法治疗血栓栓塞性脑缺血大鼠,大脑皮层局部血流量(rCBF)及脑水肿的变化。结果:缺血6小时经光量子血液治疗2小时后,rCBF于注后30min明显增加,达19.78％(P<0.01),以后各点维持在一定水平,2小时增加到19.30(P<0.05)。脑组织比重:缺血中心区未见明显改善(P>0.1)而半暗区组织比重非常明显增加(P<0.001),可见水肿明显减轻。说明光量子疗法增加rCBF,减轻半暗区水肿。     

Effects of anti-VEGF antibody on blood-brain barrier disruption in focal cerebral ischemia

Since cerebral ischemia increases expression of vascular endothelial growth factor (VEGF) and exogenous VEGF can aggravate BBB disruption in cerebral ischemia, we hypothesized that inhibition of endogenous VEGF would attenuate BBB disruption. To test this hypothesis, rats were mechanically ventilated with isoflurane and a craniotomy (5 mm in diameter) was performed to expose the cerebral cortex. Anti-VEGF antibody was applied topically (75 mug) 1 h before middle cerebral artery (MCA) occlusion and additional anti-VEGF antibody was applied (25 mug) immediately after MCA occlusion (anti-VEGF group). For the control animals, normal saline was applied instead of anti-VEGF antibody on the surface of the cortex (control group). One hour after MCA occlusion, the transfer coefficient (K(i)) of (14)C-alpha-aminoisobutyric acid and volume of (3)H-dextran (70,000 Da) distribution were determined to measure the degree of BBB disruption. There was no significant difference in vital signs, blood gases, and pericranial temperature between the control and the anti-VEGF group. In both of the groups, the K(i) of the ischemic cortex (IC) was higher than that of the corresponding contralateral cortex (CC) (p<0.05). The K(i) of the IC of the anti-VEGF group was significantly lower than that of the IC of the control group (-34%, p<0.05). The K(i) of the CC and pons were similar between these two groups. The data of volume of dextran distribution followed the same pattern as that of K(i) but without a statistical significance. Our data demonstrated that inhibition of endogenous VEGF by topical application of anti-VEGF antibody in the ischemic cortex decreased the K(i) of (14)C-AIB and suggest that endogenous VEGF is in part responsible for the BBB disruption during the early stage of focal cerebral ischemia.     

Mast cells promote blood brain barrier breakdown and neutrophil infiltration in a mouse model of focal cerebral ischemia

Blood brain barrier (BBB) breakdown and neuroinflammation are key events in ischemic stroke morbidity and mortality. The present study investigated the effects of mast cell deficiency and stabilization on BBB breakdown and neutrophil infiltration in mice after transient middle cerebral artery occlusion (tMCAo). Adult male C57BL6/J wild type (WT) and mast cell-deficient (C57BL6/J Kit^Wsh/Wsh (Wsh)) mice underwent tMCAo and BBB breakdown, brain edema and neutrophil infiltration were examined after 4 hours of reperfusion. Blood brain barrier breakdown, brain edema, and neutrophil infiltration were significantly reduced in Wsh versus WT mice (P<0.05). These results were reproduced pharmacologically using mast cell stabilizer, cromoglycate. Wild-type mice administered cromoglycate intraventricularly exhibited reduced BBB breakdown, brain edema, and neutrophil infiltration versus vehicle (P<0.05). There was no effect of cromoglycate versus vehicle in Wsh mice, validating specificity of cromoglycate on brain mast cells. Proteomic analysis in Wsh versus WT indicated that effects may be via expression of endoglin, endothelin-1, and matrix metalloproteinase-9. Using an in vivo model of mast cell deficiency, this is the first study showing that mast cells promote BBB breakdown in focal ischemia in mice, and opens up future opportunities for using mice to identify specific mechanisms of mast cell-related BBB injury.     

黄芪对大鼠脑缺血血脑屏障及脑血流的影响

利用大鼠局灶性脑缺血再灌流和全脑缺血再灌流损伤两种动物模型，观察黄芪注射液对脑缺血后再灌注期间血脑屏蔽及脑血流的保护作用。结果显示，与相庆对照组比较，不论是全脑缺血还是局灶性脑缺血１ｈ后再灌流３ｄ，应用黄芪的各组动物脑水肿明显减轻，血脑屏障通透性改善，大脑局部血流量显著增加。     

Regional brain polyamine levels in permanent focal cerebral ischemia

Transient global cerebral ischemia has been shown to induce marked changes in the polyamine pathway with a significant increase in putrescine, the product of the ornithine decarboxylase reaction. This study examined the relationship between tissue and extracellular polyamines and regional cerebral blood flow and brain edema. Six hours of focal ischemia in cats (n=10) was produced by permanent middle cerebral artery occlusion. Extracellular polyamines were measured in extracellular fluid obtained by microdialysis. Regional cerebral blood flow using laser Doppler flowmetry and specific gravity, an indicator of brain edema, were measured in contralateral (non-ischemic), penumbra and densely ischemic brain regions. A significant increase in the tissue putrescine level was found in the penumbra but there was no difference in the putrescine levels between contralateral and densely ischemic regions. There was no significant change in the spermidine and spermine levels in the three regions. Extracellular levels of putrescine and spermidine were found to be significantly lower than the tissue levels and no change in polyamines was observed in any region. Significant edema formation was observed in densely ischemic and penumbra regions. This is the first demonstration that tissue putrescine is increased in the penumbra region, an area of incomplete ischemia that is developing brain edema.     

Blood-brain barrier permeability to micromolecules and edema formation in the early phase of incomplete continuous ischemia

Summary The distribution patterns of ionic Lanthanum (La³⁺; mol.wt. 139) were evaluated after 15, 30 and 60 min of middle cerebral artery occlusion in perfused-fixed rats. Blood-brain barrier (BBB) permeability to Evans blue (EB) and horseradish peroxidase (HRP; mol. wt. 40,000) in vivo was also evaluated. Brain tissue specific gravity was measured. An increase in brain water content was found as early as 30 min following occlusion. HRP and EB extravasation was not observed. La³⁺ crossed the interendothelial clefts of venoles and capillaries at 30 and 60 min and was seen in both extracellular and intracellular brain compartments at 60 min. La³⁺ extravasation was seen in nonedematous areas bordering the regions of water accumulation. Our findings suggest that the early phase of incomplete continuous ischemia is accompanied by changes in BBB permeability and the interendothelial clefts of venoles and capillaries seem to represent one of the early sites of ischemic damage.Supported by the Alexander von Humboldt-Stiftung Foundation (SS)     

大鼠蛛网膜下腔出血后脑局部血流量与血脑屏障动态变化

目的：探讨大鼠蛛网膜下腔出血（SAH）后局部脑血流（rCBF）与血脑屏障（BBB）超微结构的动态变化规律和尼莫地平（Nim）的作用特点。方法：通过大鼠枕大池自体血注入法制备SAH后脑血管痉挛（CVS）模型，在SAH后1h、4h、12、24h、3d、7d、14d、及21d等不同时相点，利用激光普勒技术和电镜对各组大鼠局部脑血流与血脑屏障超微结构变化进行观察。结果：SAH后大鼠的rCBF明显下降且具有“两期”反应，在SAH后1h后rCBF有所恢复，4h后再度降低，并可持续至21d。BBB损害改变在SAH后早期即可观察到。Nim对rCBF降低和BBB损害均有改善作用。结论：SAH后rCBF与BBB超微结构的动态变化符合CVS的发展规律，可以反映该时期CVS的状态。早期应用Nim可以改善SAH后CVS，并对BBB的损害有一定保护作用。     

尼莫地平对脑出血患者局部脑血液、脑水肿及不同时间用药临床变化的影响

目的：动态观察尼莫地平对高血压脑出血患者局部脑血液（rCBF)、脑水肿和不同时间用药临床变化的影响。方法：随机将108例高血压脑出血患者分对照组和治疗组,并将治疗组再分为发病前12小时以内用药组和12小时以后用药组,行单光子发射断层扫描（SPECT）、临床疗效和动态观察;并随机从对照组和治疗组中分别抽出10例患者行SPCET、CT的动态观察,结果：治疗组rCBF、水肿带和临床疗效的改善显著优于对照组;12小时以内用药的临床疗效明显优于12小时以后用药。结论：早期使用尼莫地平对改善高血压脑出血后rCBF下降,提高临床疗效和减轻血肿周围水肿可能均有积极作用。     

亚低温对局灶脑缺血再灌注后脑血流、血脑屏障、神经细胞损伤作用的研究

目的对比研究不同时期亚低温（ＭＨＴ３２℃±０．２℃）对局灶脑缺血再灌注损伤的作用。方法６４只雄性ＳＤ鼠被随机分成常温（ＮＴ）、缺血期亚低温（ＭＨＴｉ）、再灌注期亚低温（ＭＨＴｒ）、缺血期加再灌注期亚低温（ＭＨＴｉ＋ｒ）四组,并用改良Ｋｏｉｚｕｍｉ＇ｓ局灶脑缺血模型,分别观察了动物缺血３小时再灌注３小时过程中,缺血周边和核心区局部脑血流（ｒＣＢＦ）改变,再灌注３小时后血脑屏障（ＢＢＢ）破坏及再灌注７２小时后缺血梗塞灶体积。结果ＭＨＴｉ＋ｒ及ＭＨＴｉ均有改善缺血周边区再灌注后急性高灌注和继发低灌流及核心区持续低灌流、减轻血脑屏障破坏、减少缺血梗塞灶体积的作用。该作用尤以ＭＨＴｉ＋ｒ为明显。ＭＨＴｒ作用有限。结论ＭＨＴｉ＋ｒ对皮层的保护作用较ＭＨＴｉ好。由此可推知,局灶脑缺血再灌注损伤是个持续的过程,亚低温治疗不但要考虑开始时间,其持续时间对疗效具有同样重要价值     

Early appearance of activated matrix metalloproteinase-9 and blood–brain barrier disruption in mice after focal cerebral ischemia and reperfusion

Blood–brain barrier (BBB) disruption is thought to play a critical role in the pathophysiology of ischemia/reperfusion. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that can degrade all the components of the extracellular matrix when they are activated. Gelatinase A (MMP-2) and gelatinase B (MMP-9) are able to digest the endothelial basal lamina, which plays a major role in maintaining BBB impermeability. The present study examined the expression and activation of gelatinases before and after transient focal cerebral ischemia (FCI) in mice. Adult male CD1 mice were subjected to 60 min FCI and reperfusion. Zymography was performed from 1 to 23 h after reperfusion using the protein extraction method with detergent extraction and affinity-support purification. MMP-9 expression was also examined by both immunohistochemistry and Western blot analysis, and tissue inhibitors to metalloproteinase-1 was measured by reverse zymography. The BBB opening was evaluated by the Evans blue extravasation method. The 88-kDa activated MMP-9 was absent from the control specimens, while it appeared 3 h after transient ischemia by zymography. At this time point, the BBB permeability alteration was detected in the ischemic brain. Both pro-MMP-9 (96 kDa) and pro-MMP-2 (72 kDa) were seen in the control specimens, and were markedly increased after FCI. A significant induction of MMP-9 was confirmed by both immunohistochemistry and Western blot analysis. The early appearance of activated MMP-9, associated with evidence of BBB permeability alteration, suggests that activation of MMP-9 contributes to the early formation of vasogenic edema after transient FCI.     

Matrix metalloproteinase-9 expression and blood brain barrier permeability in the rat brain after cerebral ischemia/reperfusion injury**☆

BACKGROUND： The integrity of the blood brain barrier （BBB） plays an important role in the patho-physiological process of cerebral ischemia/reperfusion injury. It has been recently observed that metalloproteinase-9 （MMP-9） is closely related to cerebral ischemia/reperfusion injury OBJECTIVE： This study was designed to observe MMP-9 expression in the rat brain after cerebral ischemia/reperfusion injury and to investigate its correlation to BBB permeability. DESIGN, TIME AND SETTING： This study, a randomized controlled animal experiment, was performed at the Institute of Neurobiology, Central South University between September 2005 and March 2006. MATERIALS： Ninety healthy male SD rats, aged 3-4 months, weighing 200-280 g, were used in the present study. Rabbit anti-rat MMP-9 polyclonal antibody （Boster, Wuhan, China） and Evans blue （Sigma, USA） were also used. METHODS： All rats were randomly divided into 9 groups with 10 rats in each group： normal control group, sham-operated group, and ischemia for 2 hours followed by reperfusion for 3, 6, 12 hours, 1, 2, 4 and 7 days groups. In the ischemia/reperfusion groups, rats were subjected to ischemia/reperfusion injury by suture occlusion of the right middle cerebral artery. In the sham-operated group, rats were merely subjected to vessel dissociation. In the normal control group, rats were not modeled. MAIN OUTCOME MEASURES： BBB permeability was assessed by determining the level of effusion of Evans blue. MMP-9 expression was detected by an immunohistochemical method. RESULTS： All 90 rats were included in the final analysis. BBB permeability alteration was closely correlated to ischemia/reperfusion time. BBB permeability began to increase at ischemia/reperfusion for 3 hours, then it gradually reached a peak level at ischemia/reperfusion for 1 day, and thereafter it gradually decreased. MMP-9 expression began to increase at ischemia/reperfusion for 3 hours, then gradually reached its peak level 2 days after perfusion, and thereafter it grad     

Matrix metalloproteinase-9 expression and blood brain barrier permeability in the rat brain after cerebral ischemia/reperfusion injury

BACKGROUND: The integrity of the blood brain barrier (BBB) plays an important role in the patho-physiological process of cerebral ischemia/reperfusion injury. It has been recently observed that metalloproteinase-9 (MMP-9) is closely related to cerebral ischemia/reperfusion injuryOBJECTIVE: This study was designed to observe MMP-9 expression in the rat brain after cerebral ischemia/reperfusion injury and to investigate its correlation to BBB permeability.DESIGN, TIME AND SETTING: This study, a randomized controlled animal experiment, was performed at the Institute of Neurobiology, Central South University between September 2005 and March 2006.MATERIALS: Ninety healthy male SD rats, aged 3-4 months, weighing 200-280g, were used in the present study. Rabbit anti-rat MMP-9 polyclonal antibody (Boster, Wuhan, China) and Evans blue (Sigma, USA) were also used.METHODS: All rats were randomly divided into 9 groups with 10 rats in each group: normal control group, sham-operated group, and ischemia for 2 hours followed by reperfusion for 3,6,12 hours, 1,2,4 and 7 days groups. In the ischemia/reperfusion groups, rats were subjected to ischemia/reperfusion injury by suture occlusion of the right middle cerebral artery. In the sham-operated group, rats were merely subjected to vessel dissociation. In the normal control group, rats were not modeled.MAIN OUTCOME MEASURES: BBB permeability was assessed by determining the level of effusion of Evans blue. MMP-9 expression was detected by an immunohistochemical method.RESULTS: All 90 rats were included in the final analysis. BBB permeability alteration was closely correlated to ischemia/reperfusion time. BBB permeability began to increase at ischemia/reperfusion for 3 hours, then it gradually reached a peak level at ischemia/reperfusion for 1 day, and thereafter it gradually decreased. MMP-9 expression began to increase at ischemia/reperfusion for 3 hours, then gradually reached its peak level 2 days after perfusion, and thereafter it gradually decreased.CONCLUSION: MMP-9 expression increases in rat brain tissue after focal cerebral ischemia/reperfusion injury, which correlates with increased permeability of the BBB.     

Cerebral microembolization in the rat: Changes in blood-brain barrier permeability and cerebral blood flow as related to the degree of ischemia

Unilateral cerebral microembolism was performed in the rat by injecting calibrated, 50 micrometers in diameter, carbonized microspheres into the internal carotid artery. The events that follow brain ischemia due to cerebral embolization were studied by the analysis of the blood-brain barrier (BBB) function, the degree of regional cerebral blood flow (CBF) and the development of brain edema. Two hours after embolization there was no change in the brain water content. The local CBF (14C-ethanol technique) was only reduced in the ipsilateral hemisphere. Twenty-four hours after embolization the brain water content was increased significantly in the ipsilateral, but not in the contralateral hemisphere. Local CBF further decreased in the ipsilateral hemisphere and a reduction in flow was also observed in the contralateral hemisphere. Embolization led to an increase in the BBB permeability, analysed as regional penetrability of 3H-dextran and of Evans blue-albumin complexes, which was restricted to the side of the injection of the microspheres.     

局灶缺血诱导大鼠脑肝细胞生长因子表达的动态观察

目的:探讨肝细胞生长因子(HGF)在局灶脑缺血边缘区表达的动态变化及其意义。方法:采取线栓法建立局灶脑缺血模型,根据缺血时间分为1h、3h、12h、24h组,RT-PCR法检测HGF的表达及其动态变化。结果:缺血1h脑缺血边缘区即有HGF的表达,且随着缺血时间的延长其表达逐渐增强,24h尤为明显。结论:HGF在局灶脑缺血诱导的高表达可能在脑缺血损伤组织的保护及修复过程中起重要作用。     

Effect of the kappa-1 opioid agonist CI-977 on ischemic brain damage and cerebral blood flow after middle cerebral artery occlusion in the rat

The effects of the kappa-1 opioid agonist CI-977 upon the volume of ischemic brain damage (defined using quantitative neuropathology) and local cerebral blood flow (CBF) (defined using quantitative [¹⁴C]iodoantipyrine autoradiography) have been examined at 4 h and 30 min, respectively, after permanent middle cerebral artery (MCA) occlusion in halothane-anesthetised rats. Treatment with CI-977 (0.3 mg/kg, s.c.) 30 min before and 30 min after occlusion of the MCA reduced the volume of infarction in the cerebral hemisphere (reduced by 27% when compared to vehicle;P<0.05) and cerebral cortex (reduced by 32%;P<0.05), despite a marked and sustained hypotension, with only minimal effect on damage in the caudate nucleus. In the hemisphere contralateral to the occluded MCA, treatment with CI-977 (0.3 mg/kg, s.c.) 30 min prior to the induction of ischemia failed to demonstrate any significant effect on either the level of local CBF in any of the 25 regions examined or on the volume of low CBF determined by frequency distribution analysis. In the hemisphere ipsilateral to MCA occlusion, CI-977 failed to produce statistically significant alterations in either the level of local CBF in 23 of the 25 regions or on the volume of low CBF, but areas of hyperemia were observed in both the medial caudate nucleus and lateral thalamus (local CBF increased by 65% and 86%, respectively, when compared to vehicle). The results of the present study indicate that the kappa-1 opioid agonist CI-977 is neuroprotective in a rat model of focal cerebral ischemia where key physiological variables have been assessed throughout the entire post-ischemic period, and fail to demonstrate that the neuroprotective effects of CI-977 in this model are due to improved blood flow to ischemic tissue.     

The response of focal ischemic cerebral edema to dexamethasone

Summary Twenty-four h after permanent occlusion of the middle cerebral artery (MCA) in the cat, the hemispheric swelling due to edema is markedly reduced under treatment with large doses of dexamethasone than is the case with the untreated group. The increase of regional water and sodium content in the MCA territory is less in the dexamethasone treated group, whereas the potassium changes in the ischemic tissue showed only small differences between the two groups. The potassium content of the non-ischemic tissue is slightly increased in the dexamethasone treated animals when comparing with the untreated group. RISA activity in the tissue is increased in the grey and the white matter of both groups. The less marked RISA^–131 activity in the cortical grey matter of the treated animals indicates blood-brain barrier damage of a smaller degree due to dexamethasone. These findings indicate a beneficial effect of dexamethasone on local ischemic edema. Regarding our results and the pharmacokinetics of this steroid the dexamethasone loading of a patient has to be in the range of about 100 mg per day for the adult, and has to be started immediately after the onset of a stroke.

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Zusammenfassung Vierundzwanzig Stunden nach permanentem Verschluß der Arteria cerebri media der Katze ist die ödembedingte Volumenzunahme der geschädigten Hemisphäre unter hochdosierter Dexamethasonbehandlung gegenüber nichtbehandelten Tieren deutlich geringer. Auch der Vergleich der regionalen Wasser- und Natriumzunahme ergibt für die behandelten Tiere geringere Werte. Gleichzeitig findet sich ein nur geringerer Kaliumverlust aus dem geschädigten Gewebe, während sich unter Dexamethasongabe in den ungeschädigten Hirnregionen eine erhöhte Kaliumkonzentration nachweisen läßt. Die RISA^–131-Aktivität im Hirngewebe, Indikator für eine Blut-Hirn-Schrankenschädigung, ist 24 h nach Ischämiebeginn sowohl in der grauen als auch der weißen Substanz in beiden Gruppen erhöht, wobei das Ausmaß der BHS-Schädigung im betroffenen Cortexareal der behandelten Gruppe gegenüber den Kontrollen wiederum geringer ist. Diese Befunde sprechen unter Berücksichtigung der Pharmakokinetik des Steroids für eine günstige Wirkung bei der Therapie des lokalen ischämischen Hirnödems. Voraussetzung scheint jedoch die frühzeitige, hochdosierte Steroidgabe zu sein, wobei eine Tagesdosis entsprechend über 100 mg Dexamethason beim erwachsenen Menschen erreicht werden sollte.

     

大鼠脑出血后脑血流和脑水分含量变化的研究

研究大鼠脑出血后局部脑血流量（ｒＣＢＦ）与脑水分变化的规律及影响因素。用立体定向法自体血回注建立大鼠脑尾状核出血模型，分别在２４ｈ内不同时限用氢清除法测定ｒＣＢＦ，干湿重法测定脑水分含量，发现出血后１０ｍｉｎ同侧ｒＣＢＦ即下降，１ｈ达最低水平，出血量大时对侧半球也有明显下降；双侧脑水分含量均明显增加，其高峰期晚于ｒＣＢＦ的下降。说明脑出血后迅速出现广泛的低灌注和脑水肿     

Influence of blood pressure on blood-brain barrier function in brain ischemia

The influence of systemic blood pressure on blood-brain barrier leakage and hemorrhage in brain ischemia was evaluated in Sprague-Dawley rats with blood pressures at the lower and upper limit normally found in these animals when anesthetized on 70% N2O:30% O2. 24 h after unilateral cerebral microembolization - when significant increases in water content and barrier permeability and decrease in blood flow is present - the extravasation of Evans Blue-albumin and inulin as well as hemorrhage in the infarcted brain area was considerably more prominent in animals with the higher blood pressure. The findings imply that attempts to elevate pressure, as well as subacute surgical circulatory reconstruction to increase perfusion of an ischemic area, may be potentially harmful.     

双侧肾上腺切除大鼠脑缺血后血脑屏障破坏的研究

目的观察脑缺血时体内自身的糖皮质激素变化对血脑屏障（ＢＢＢ）的影响。方法采用线栓法造成脑缺血模型,用辣根过氧化物酶组织化学染色的方法,观察双侧肾上腺切除大鼠局灶脑缺血后血脑屏障的改变。结果双侧肾上腺切除后脑缺血组（Ａ组）大鼠ＢＢＢ破坏的范围为１０．１０１±１．４１１ｍｍ２;单纯脑缺血组（Ｂ组）大鼠ＢＢＢ破坏范围为６．１９１±１．０４５ｍｍ２,Ａ组大鼠ＢＢＢ破坏的范围大于Ｂ组大鼠ＢＢＢ破坏的范围（Ｐ＜０．０１）。结论脑缺血时体内自身的糖皮质激素升高对ＢＢＢ具有保护作用。     

磁共振显像对缺血性脑水肿的动态实验研究

目的　探讨缺血性脑水肿的演变规律及慢性高血压对其的影响 ,评价磁共振显像 (MRI)在脑缺血研究中的价值。方法　采用肾血管性高血压鼠 (RHR)与正常鼠对比 ,制成局部脑梗死模型 ,应用MRI对缺血性脑水肿急性期进行动态研究 ,选择病灶所在最大层面测量病灶中心区和对侧对应区的T2 值和 ρ值。 结果　在缺血后 1hT2 与 ρ值就已开始明显延长 ,在缺血 7天内 ,MRI均有明显信号改变。高血压鼠组T2 值在缺血早期均较对照组延长 ,该组病灶对侧半球也可出现信号改变。结论　MRI是早期检测脑水肿的直接方法 ,高血压鼠脑水肿形成较正常鼠早且程度重 ,其病灶对全脑血流动力学亦产生影响。以上结果对临床治疗有指导价值。