Conjugated superoxide dismutase reduces extent of caudate injury after transient focal ischemia in cats.

We tested the efficacy of preischemic and postischemic systemic treatment with 30,000 units polyethylene glycol-conjugated superoxide dismutase in a reperfusion model of focal cerebral ischemia. Forty-one anesthetized cats underwent 2 hours' occlusion of the left middle cerebral artery and both common carotid arteries followed by 4 hours of reperfusion. Cats were blindly assigned to one of three groups: treatment with vehicle (10% polyethylene glycol in saline, n = 17), pretreatment with drug 3 hours before ischemia (n = 12), and posttreatment with drug at the time of reperfusion (n = 12). Size of the ischemic injury was calculated from 2,3,5-triphenyltetrazolium chloride staining. Injury in the caudate nucleus was significantly reduced with pretreatment (28 +/- 6% of ipsilateral caudate volume, mean +/- SEM) compared with the vehicle (56 +/- 8%). Posttreatment did not significantly ameliorate caudate injury (46 +/- 10%). Between the first and second hours of ischemia ipsilateral caudate blood flow determined using microspheres increased significantly from 11 +/- 4 to 16 +/- 5 ml/min/100 g with pretreatment, but blood flow remained constant throughout ischemia with vehicle (8 +/- 2 ml/min/100 g) and posttreatment (10 +/- 3 ml/min/100 g). The size of cortical injury (vehicle, 17 +/- 5%; pretreatment, 11 +/- 3%; posttreatment, 17 +/- 5% of hemispheric volume) did not differ significantly among groups. Somatosensory evoked potential recovery did not differ among groups. We conclude that pretreatment with conjugated superoxide dismutase can ameliorate the extent of injury in an end-artery region, such as the caudate nucleus, in a reperfusion model of focal ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of lipopolysaccharide priming on acute ischemic brain injury

BACKGROUND AND PURPOSE: Infection has been implicated as a stroke risk factor. Activation and infiltration of polymorphonuclear neutrophils (PMNs) after cerebral ischemia may contribute to ischemic brain injury. This study was conducted to investigate how enhanced postischemic PMN infiltration by lipopolysaccharide (LPS) altered the acute ischemic outcomes. METHODS: LPS (0.05 mg/kg SC) or vehicle was given to Long-Evans male rats 24 hours before ischemia. Focal cerebral ischemia was induced by temporary ligation of the right middle cerebral artery and both common carotid arteries for 45 minutes. Animals were killed 6 and 24 hours after reperfusion to determine the extent of PMN infiltration (myeloperoxidase assay), brain edema (wet-dry weight method), and vascular injury (fluorescein isothiocyanate-conjugated dextran extravasation). The infarct volumes were measured on the basis of TTC stain 24 hours after ischemia. RESULTS: LPS had little effect on body temperature or peripheral white count but substantially enhanced PMN infiltration into the ischemic right middle cerebral artery cortex on the basis of myeloperoxidase activity (6 hours: control, 0 U/g; LPS, 0.186+/-0. 025 U/g; 24 hours: control, 0.185+/-0.025 U/g; LPS, 0.290+/-0.040 U/g; P<0.001) and morphological studies. The extent of vascular injury defined by the extravasation of fluorescein isothiocyanate-conjugated dextran into the ischemic tissue (6 hours: control, 3.11+/-0.41 microliter/mg protein; LPS, 0.48+/-0.16 microliter/mg protein; 24 hours: control, 1.77+/-0.23 microliter/mg protein; LPS, 0. 90+/-0.19 microliter/mg protein; P<0.001) and brain edema determined by the brain water content (6 hours: control, 84.77+/-1.63%; LPS, 82. 09+/-1.25%; 24 hours: control, 89.40+/-0.43%; LPS, 87.88+/-0.58%; P<0.01) were paradoxically reduced by LPS priming. LPS-primed rats also had smaller infarct volumes (control, 135+/-5 mm(3); LPS, 108+/-12 mm(3); P<0.05). CONCLUSIONS: Enhanced postischemic PMN infiltration is anticipated to facilitate ischemic brain injury. Contrary to this expectation, results from the present study suggest that an increase in postischemic PMN infiltration after LPS priming was not detrimental. These findings challenge the notion that postischemic PMN infiltration is uniformly deleterious.     

Mild hypothermia reduces infarct size resulting from temporary but not permanent focal ischemia in rats.

BACKGROUND AND PURPOSE: Mild hypothermia (32-35 degrees C) has been repeatedly shown in laboratory models to reduce damage resulting from global cerebral ischemic insults. Little information is available, however, regarding the protective potential of mild hypothermia against focal ischemia. We designed the present study to determine whether mild hypothermia influences outcome from either temporary or permanent middle cerebral artery occlusion in the rat. METHODS: In experiment 1 (permanent occlusion), mechanically ventilated, halothane-anesthetized spontaneously hypertensive rats underwent permanent ligation of the middle cerebral artery. Pericranial temperature was maintained at either 37 degrees C (n = 11) or 33 degrees C (n = 11) during the first 2 hours of occlusion. In experiment 2 (temporary occlusion), the vessel was occluded for 1 hour only. Pericranial temperature was controlled at either 37 degrees C (n = 12) or 33 degrees C (n = 14) during ischemia and for 1 hour after reperfusion. In both experiments, the rats were allowed to recover, with neurological function scored at 24 and 96 hours after onset of ischemia. Cerebral infarct volume (as determined by nitro blue tetrazolium staining) was planimetrically evaluated 96 hours after onset of ischemia. RESULTS: No difference in infarct volume was observed between groups undergoing permanent occlusion (177 +/- 53 mm3 for 37 degrees C rats, 167 +/- 71 mm3 for 33 degrees C rats [mean +/- SD]). Although neurologic function correlated with infarct volume at 96 hours (all animals in experiment 1 combined; p less than 0.01), we were unable to demonstrate an intergroup difference in function. In animals undergoing temporary occlusion, mean +/- SD infarct volume was 48% less in the hypothermic group (89 +/- 54 mm3 for 37 degrees C, 46 +/- 31 mm3 for 33 degrees C; p less than 0.03). Neurological function again correlated with infarct size (p less than 0.02), but improvement in function approached significance for the hypothermic group (p less than 0.06) at 24 hours after reperfusion only. CONCLUSIONS: Benefits from mild hypothermia may be obtained under conditions of temporary but not permanent middle cerebral artery occlusion in the rat.     

Hydroxyethyl starch 200/0.5 reduces infarct volume after embolic stroke in rats.

BACKGROUND AND PURPOSE: We evaluated isovolumic hemodilution with hydroxyethyl starch 200/0.5 in a rat model of focal cerebral ischemia. This compound avoids the unfavorable viscosity and erythrocyte aggregation abnormalities of low molecular weight dextran during administration over a period of several days. METHODS: Sprague-Dawley rats, anesthetized with 0.5-1% halothane and 70% N2O, were subjected to silicon cylinder (treated and control groups) or sham (sham group) embolization of the cerebral circulation. Thirty minutes after embolization, the treated group (n = 5) was infused with 11 ml/kg of 10% hydroxyethyl starch 200/0.5, and the control (n = 5) and sham (n = 4) groups were infused with saline for 1 hour. In the treated group, 7.1 ml/kg of blood was withdrawn. After 24 hours, the animals were reanesthetized, and cerebral blood flow was determined with [14C]iodoantipyrine. Alternative brain slices were either incubated with 2,3,5-triphenyltetrazolium chloride for infarct volume determination or frozen for ischemic volume and cerebral blood flow determination using autoradiography. RESULTS: The hematocrit in the treated group was reduced from (mean +/- SEM) 46 +/- 1% to 35 +/- 2% at 1.5 hours (p < 0.01). Cortical blood flow was within the normal range of 115-185 ml/min/100 g, except for the ischemic cortex in the embolized groups, treated and control. The ischemic and infarct volume of the treated group was reduced by 74% (p < 0.05) and 89% (p < 0.05), respectively, from the control group. The treated and sham ischemic and infarct volumes were not statistically different. CONCLUSIONS: These data suggest that hydroxyethyl starch 200/0.5 could be an effective treatment for ischemic stroke when administered early, because it reduces infarct and ischemic volumes from control values to levels indistinguishable from those of the sham group.     

Neuroprotective effects of female gonadal steroids in reproductively senescent female rats

BACKGROUND AND PURPOSE: Young adult female rats sustain smaller infarcts after experimental stroke than age-matched males. This sex difference in ischemic brain injury in young animals disappears after surgical ovariectomy and can be restored by estrogen replacement. We sought to determine whether ischemic brain injury continues to be smaller in middle-aged, reproductively senescent female rats compared with age-matched males and to test the effect of ovarian steroids on brain injury after experimental stroke in females. METHODS: Four groups of 16-month old Wistar rats (males [n=9], untreated females [n=9], and females pretreated with 17beta-estradiol [25-microgram pellets administered subcutaneously for 7 days; n=9] or progesterone [10-mg pellets administered subcutaneously for 7 days; n=9] were subjected to 2 hours of middle cerebral artery occlusion with the intraluminal filament technique, followed by 22 hours of reperfusion. Physiological variables and laser-Doppler cerebral cortical perfusion were monitored throughout ischemia and early reperfusion. In a separate cohort of males (n=3), untreated females (n=3), females pretreated with 17beta-estradiol (n=3), and females pretreated with progesterone (n=3), end-ischemic regional cerebral blood flow was measured by [(14)C]iodoantipyrine autoradiography. RESULTS: As predicted, infarct size was not different between middle-aged male and female rats. Cortical infarcts were 21+/-5% and 31+/-6% of ipsilateral cerebral cortex, and striatal infarcts were 44+/-7% and 43+/-5% of ipsilateral striatum in males and females, respectively. Both estrogen and progesterone reduced cortical infarct in reproductively senescent females (5+/-2% and 16+/-4% in estrogen- and progesterone-treated groups, respectively, compared with 31+/-6% in untreated group). Striatal infarct was smaller in the estrogen- but not in the progesterone-treated group. Relative change in laser-Doppler cerebral cortical perfusion from preischemic baseline and absolute end-ischemic regional cerebral blood flow were not affected by hormonal treatments. CONCLUSIONS: We conclude that the protection against ischemic brain injury found in young adult female rats disappears after reproductive senescence in middle-aged females and that ovarian hormones alleviate stroke injury in reproductively senescent female rats by a blood flow-independent mechanism. These findings support a role for hormone replacement therapy in stroke injury prevention in postmenopausal women.     

sigma(1)-receptor ligand 4-phenyl-1-(4-phenylbutyl)-piperidine affords neuroprotection from focal ischemia with prolonged reperfusion

BACKGROUND AND PURPOSE: We previously showed that the intravenous administration of the potent final sigma(1)-receptor ligand 4-phenyl-1-(4-phenylbutyl)-piperidine (PPBP) provides neuroprotection against transient focal cerebral ischemia and that the protection depends on treatment duration. We tested the hypothesis that PPBP would provide neuroprotection in a model of transient focal ischemia and 7 days of reperfusion in the rat as assessed with neurobehavioral outcome and infarction volume. METHODS: Under the controlled conditions of normoxia, normocarbia, and normothermia, halothane-anesthetized male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion (MCAO) with the intraluminal suture occlusion technique. We used laser Doppler flowmetry to assess MCAO. At 60 minutes after the onset of ischemia, rats were randomly assigned to 1 of 4 treatment groups in a blinded fashion and received a continuous intravenous infusion of control saline or 0.1, 1, or 10 micromol. kg(-1). h(-1) PPBP for 24 hours. Neurobehavioral evaluation was performed at baseline (3 to 4 days before MCAO) and at 3 and 7 days of reperfusion. Infarction volume was assessed with triphenyltetrazolium chloride staining on day 7 of reperfusion in all rats. RESULTS: Triphenyltetrazolium chloride-determined infarction volume of ipsilateral cortex was smaller in rats treated with 10 micromol. kg(-1). h(-1) PPBP (n=15, 68+/-12 mm(3), 18+/-3% of contralateral structure, P<0.05) (mean+/-SEM) compared with corresponding rats treated with saline (n=15, 114+/-11 mm(3), 31+/-3% of contralateral structure). PPBP did not provide significant neuroprotection in the caudoputamen complex. Although MCAO was associated with several alterations in behavior, the treatment with PPBP had no effect on behavioral outcomes. CONCLUSIONS: The data demonstrate that the potent final sigma(1)-receptor ligand PPBP decreases cortical infarction volume without altering neurobehavior after transient focal ischemia and prolonged reperfusion in the rat.     

TAK-779, a nonpeptide CC chemokine receptor antagonist, protects the brain against focal cerebral ischemia in mice.

The effect of a nonpeptide CC chemokine receptor antagonist, TAK-779, on ischemic brain injury resulting from 1-hour middle cerebral artery occlusion followed by 48-hour reperfusion was examined in ddY mice. On intracerebroventricular injection of vehicle or TAK-779, infarct volume in the vehicle-treated group was 44.2 +/- 13.2% of the contralateral hemispheric volume, and TAK-779 (25 and 250 ng/mouse) dose-dependently reduced the infarct volume to 35.0 +/- 12.2% and 31.1 +/- 12.9%, respectively. On intravenous injection, infarct volume in the vehicle-treated group was 32.0 +/- 16.1%, and TAK-779 (5 microg per 20 g body weight) significantly reduced this to 22.0 +/- 10.5%. The results showed for the first time that a nonpeptide chemokine receptor antagonist is protective against ischemic brain injury.     

Deficiency of myeloperoxidase increases infarct volume and nitrotyrosine formation in mouse brain.

Peroxynitrite is responsible for nitration in vivo, whereas myeloperoxidase can also catalyze protein nitration in the presence of high NO2(-) levels. Recent reports of myeloperoxidase-mediated enzyme inactivation or lipid peroxidation have suggested a role of myeloperoxidase in various pathological conditions. To clarify the role of myeloperoxidase in ischemic brain injury, the authors measured nitrotyrosine formation and infarct volume in myeloperoxidase-deficient or wild-type mice subjected to 2-hour focal cerebral ischemia-reperfusion. Twenty-four hours after reperfusion, infarct volume was significantly larger in myeloperoxidase-deficient mice than in wild-type mice (81 +/- 20 mm(3) vs. 52 +/- 13 mm(3), P < 0.01), and nitrotyrosine levels in the infarct region were higher in myeloperoxidase-deficient mice than in wild-type mice (13.4 +/- 6.1 microg/mg vs. 9.8 +/- 4.4 microg/mg, P = 0.13). Fourteen hours after reperfusion, the nitrotyrosine level was significantly higher in myeloperoxidase-deficient mice than in wild-type mice (3.3 +/- 2.9 microg/mg vs. 1.4 +/- 0.4 microg/mg, P < 0.05). The authors conclude that the absence of myeloperoxidase increases ischemic neuronal damage in vivo, and that the myeloperoxidase-mediated pathway is not responsible for the nitration reaction in cerebral ischemia-reperfusion.     

Effects of fluid management on edema volume and midline shift in a rat model of ischemic stroke

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the effects of fluid management on brain water content (BW) and midline shift (MLS) after a focal cerebral ischemic insult. METHODS: A suture model was used to induce focal cerebral ischemia for 90 minutes (n=44). The rats were randomly assigned to 3 groups 2. 5 hours after reperfusion: dehydration (n=24), control (n=8), or hydration (n=12). BW was obtained with the wet-dry weight method 24 hours after middle cerebral artery (MCA) occlusion. In addition, MRI were obtained (n=31) 24 hours after the onset of ischemia so that the ratio of hemispheric volumes ipsilateral (IH) and contralateral (CH) to the infarct and the extent of MLS could be obtained. RESULTS: Across the range from moderate dehydration to intravascular volume expansion with isotonic saline, BW of the IH increased linearly as a function of change in body weight (r(2)=0.89), whereas few changes in relation to body weight were observed in CH, indicating a preferential effect of fluid management on the infarcted hemisphere. Furthermore, the hemispheric volume ratio (IH/CH) and MLS also increased in relation to changes in body weight. However, paradoxical increases in BW, IH/CH, and extent of MLS were observed in comparison with controls when severe dehydration was produced with high-dose mannitol. CONCLUSIONS: Changes in ischemic BW by fluid management correlated closely with changes in body weight except when high-dose mannitol was used. Mannitol, as a dehydrating agent, may be associated with bimodal effects, with a high dose aggravating ischemic BW.     

Influence of the duration of ischemia and reperfusion on infarct volume and microvascular damage in mice

OBJECTIVES: Focal cerebral ischemia is responsible for alterations of vascular permeability, and the loss of microvascular integrity is a primary source of subsequent hemorrhages. We evaluated the influence of different durations of ischemia and reperfusion on infarction size and microvascular damage after focal cerebral ischemia in the mouse.METHODS: C57BL/6 mice (n=39) were subjected to focal cerebral ischemia (I) and reperfusion (R). Consecutive brain sections were analysed for infarction volumes (Nissl-staining) and for collagen type IV (immunohistochemistry and western blot).RESULTS: Infarction size (percentage of the infarction volume versus ipsilateral hemisphere) increased with total time of ischemia and reperfusion: 19+/-2% (I3R0), 30+/-2% (I3R3), 36+/-4% (I3R12), 41+/-4% (I1R24), 45+/-6% (I2R24) and 58+/-2% (I3R24). The ischemic hemispheres showed a significant progressive reduction of collagen type IV positive vessels (ischemic versus non-ischemic contralateral area): 90+/-3% (I3R0), 88+/-1% (I3R3), 82+/-3% (I3R12), 85+/-3% (I1R24), 79+/-3% (I2R24), 72+/-2% (I3R24).CONCLUSIONS: Both prolonged ischemia and reperfusion lead to an increased infarction volume, as well as progressive microvascular damage.     

Immediate or delayed mild hypothermia prevents focal cerebral infarction

The protective effect of mild hypothermia was studied in rodent models of both permanent and transient focal cerebral ischemia. In Expt. 1, Wistar rats were exposed to 6 h permanent ischemia by bilateral occlusion of both common carotid arteries and right middle cerebral artery. In Expt. 2, animals were exposed to 3 h transient ischemia followed by 21 h reperfusion, and in Expt. 3, 3 h transient ischemia was followed by 69 h of reperfusion. Expt. 4 used 3 h transient ischemia followed by 3 h reperfusion. In Expt. 1, animals maintained at 37 degrees C rectal (normothermia) suffered a mean infarct volume (+/- S.D.) of 142 +/- 44 mm3 (n = 6), which was reduced for those exposed to permanent hypothermic (32 degrees C) ischemia to 56 +/- 64 mm3 (n = 10) (P less than 0.05). In Expt. 2, normothermic ischemia and reperfusion resulted in an infarction of 211 +/- 35 mm3 (n = 6). Intra-ischemic hypothermia (32 degrees C) followed by 21 h of normothermic reperfusion resulted in 17 +/- 12 mm3 of infarction (n = 9) (P less than 0.001). Hypothermia for either the first or second 1.5 h of the 3 h ischemic insult reduced the infarct volume to 116 +/- 76 mm3 (n = 6) (P less than 0.05) or 108 +/- 73 mm3 (n = 7) (P less than 0.01), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of C 1 esterase inhibitor on ischemia: reperfusion injury in the rat brain]

BACKGROUND: Despite the current interest in thrombolytic therapy for acute stroke, ischemia-reperfusion injury remains a potentially hazardous complication. The complement system is thought to play a major role in initiating some of the inflammatory events occurring in the reperfusion injury. This study was conducted to explore the effect of C 1 esterase inhibitor (C 1 INH) on the reperfusion injury in rat middle cerebral artery (MCA) occlusion-reperfusion model. METHODS: Twenty-nine male Wistar rats were used. Intraluminal MCA occlusion was performed for 60 minutes. Just before the reperfusion, C 1 INH(50 IU/kg, C 1 INH group, n = 15) or saline (control group, n = 14) was administrated. Forty-eight hours after the reperfusion, infarct volume and myeloperoxidase(MPO) activity of the brain were evaluated. RESULT: Infarct volume and MPO activity were significantly smaller in the C 1 INH group(86.5 +/- 76.8 mm3, 0.38 +/- 0.30 U/g) than in control group(179 +/- 92.8 mm3, 1.37 +/- 0.46 U/g) (p < 0.01). CONCLUSION: The results of this study provided the first evidence that C 1 INH reduced polymorphonuclear leukocytes(PMN) accumulation and reperfusion damage in the brain.     

Exercise pre-conditioning strengthens brain microvascular integrity in a rat stroke model

Increasing evidence indicates that physical activity reduces brain damage after stroke. The purpose of this study was to determine whether exercise-induced neuroprotection is associated with improved brain integrity in stroke.Adult male Sprague-Dawley rats (3 months old, n=38) exercised on a treadmill, which required repetitive locomotor movement, for 30 minutes each day for 3 weeks. Then, using an intraluminal filament, stroke was induced by either 2 hours middle cerebral artery (MCA) occlusion followed by 24 or 48 hours of reperfusion. Brain damage was determined by evaluating brain infarction and brain edema, as well as ultrastructural alteration in endothelial-matrix-astrocyte interfaces.Pre-ischemic motor exercise significantly (p<0.01) reduced infarct volume in the frontoparietal cortex and the dorsolateral striatum by 79%. By comparing the percentage difference in brain volume between the right (stroke site) and left hemispheres, we demonstrated a significant (p<0.01) reduction in brain edema associated with reduced infarct volume in a 3 week exercise group (Group 1, n=10) and a 3 week exercise plus 3 week rest group (Group 2, n=10). Edema in cortex and striatum was 19 +/- 4% without exercise pre-conditioning (n=10), in contrast to 5 +/- 3% (Group 1) or 6 +/- 4% (Group 2). The thickness of the basal lamina was enhanced by exercise. In ischemic rats without pre-exercise, alterations in microvessel ultrastructure with decreased luminal area, parenchymal edema and swollen astrocyte end-feet, as well as an abnormally thin basal lamina were observed. In contrast, exercise pre-conditioning significantly reduced the ischemic alterations, decreasing brain edema and increasing basal lamina thickness.This study suggests that exercise pre-conditioning reduces brain injury by decreasing cerebral permeability and enhancing brain integrity after stroke. This exercise-induced endogenous neuroprotection could be an effective strategy to ameliorate ischemic brain injury from stroke.     

Attenuated neuropathology by nilvadipine after middle cerebral artery occlusion in rats

We investigated the effects of nilvadipine, a calcium antagonist, on cerebral ischemia in rats. Under halothane anesthesia, 30 rats had a 3-0 nylon suture introduced through the extracranial internal carotid artery to occlude the left middle cerebral artery. Nilvadipine was dissolved in polyethylene glycol 400. Immediately following occlusion, group 1 rats (n = 10) were treated subcutaneously with vehicle and group 2 and 3 rats were treated with 1.0 (n = 10) and 3.2 (n = 10) mg/kg nilvadipine, respectively. Perfusion fixation was performed 24 hours later, and the histopathologic outcomes were quantified. In group 1 infarct volume was 28.2 +/- 11.4% of the total cerebral volume; in groups 2 and 3 infarct volumes were 25.5 +/- 11.6% (NS) and 13.9 +/- 9.2% (p less than 0.05 different from group 1), respectively. Nilvadipine decreased ischemic neuronal injury in a dose-dependent manner and may be of use in the treatment of cerebral ischemia.     

Tumor necrosis factor-alpha neutralization reduced cerebral edema through inhibition of matrix metalloproteinase production after transient focal cerebral ischemia.

After focal cerebral ischemia, tumor necrosis factor-alpha deteriorates cerebral edema and survival rate. Therefore, tumor necrosis factor-alpha neutralization could reduce cerebral microvascular permeability in acute cerebral ischemia. Left middle cerebral artery occlusion for 120 mins followed by reperfusion was performed with the thread method under halothane anesthesia in Sprague-Dawley rats. Antirat tumor necrosis factor-alpha neutralizing monoclonal antibody with a rat IgG Fc portion (15 mg/kg) was infused intravenously right after reperfusion. Stroke index score, infarct volume, cerebral specific gravity, and the endogenous expression of tumor necrosis factor-alpha, matrix metalloproteinase (MMP)-2, MMP-9, and membrane type 1-MMP in the brain tissue were quantified in the ischemic and matched contralateral nonischemic hemisphere. In the antitumor necrosis factor-alpha neutralizing antibody-treated rats, infarct volume was significantly reduced (P=0.014, n=7; respectively), and cerebral specific gravity was dramatically increased in the cortex and caudate putamen (P<0.001, n=7; respectively) in association with a reduction in MMP-9 and membrane type 1-MMP upregulation. Tumor necrosis factor-alpha in the brain tissue was significantly elevated in the ischemic hemisphere 6 h after reperfusion in the nonspecific IgG-treated rats (P=0.021, n=7) and was decreased in the antitumor necrosis factor-alpha neutralizing antibody-treated rats (P=0.001, n=7). Postreperfusion treatment with antirat tumor necrosis factor-alpha neutralizing antibody reduced brain infarct volume and cerebral edema, which is likely mediated by a reduction in MMP upregulation.     

Administration of selective endothelin receptor type A antagonist Ro 61-1790 does not improve outcome in focal cerebral ischemia in cat.

The authors examined the effect of selective endothelin (ET) receptor type A (ET(A)) antagonism on histological and functional recovery in cat at 24 hours after reversible middle cerebral artery occlusion (MCAO). A novel and specific ET(A) antagonist, Ro 61-1790 [5-methylpyridine-2-sulfonic acid-6-(2-hydroxyethoxy)-5-(2-methoxyphenoxy)-2-(2-1H-tetrazol-5-y l-pyridin-4-yl)-pyrimidin-4-ylamide sodium salt (1:2)] (Roche, Basel, Switzerland), was used at doses that produced steady-state plasma concentrations and abolished ET-induced pial arteriolar vasoconstriction. In a cranial window preparation, 8 nmol/L ET constricted pial arterioles by 33 +/- 18% (mean +/- SD), but this response was ablated by intravenous Ro 61-1790 treatment (10-mg/kg bolus, 4-mg/kg/h infusion). In additional animal cohorts, halothane-anesthetized cats were treated with 90 minutes of MCAO and 24 hours of reperfusion. Animals received Ro 61-1790 infusion beginning at the onset of reperfusion and continuing for 6 or 24 hours (n = 41). Control cats were treated with 0.9% saline by intravenous infusion throughout reperfusion. There was no difference in injury volume or neurologic evaluation score in saline-treated cats (n = 11; caudate 24 +/- 28%, cortical injury 7.5 +/- 5% of ipsilateral structure; score 52 +/- 8) versus the results in cats treated with Ro 61-1790 for either 24 hours (n = 6; caudate 22 +/- 23%, cortex 6 +/- 5%, injury volume of ipsilateral structure; score 55 +/- 3) or 6 hours (n = 11; caudate 33 +/- 30%, cortex 12 +/- 14%, injury volume of ipsilateral structure; score 50 +/- 10). Mortality was greatest in the 24-hour drug treatment group. These data suggest that blockade of ET(A) receptor activity is not beneficial to tissue or functional outcomes from experimental stroke in cat.     

Postischemic (S)-emopamil therapy ameliorates focal ischemic brain injury in rats

(S)-Emopamil is a calcium channel blocker of the phenylalkylamine class, having potent serotonin S2 antagonistic properties and high blood-brain barrier penetrability. Previous studies have documented cerebroprotective effect in animal models of both focal and global ischemia. The present study was undertaken to define the postischemic "window" of therapeutic efficacy for this agent. Sprague-Dawley rats were subjected to permanent proximal middle cerebral artery occlusion, combined with an initial 30-minute period of halothane-induced hypotension (50 mm Hg). (S)-Emopamil (20 mg/kg) was administered intraperitoneally either 20-30 minutes prior to middle cerebral artery occlusion or 1 hour, 2 hours, or 3 hours following occlusion. Treated groups received a second similar dose 2.5 hours later and twice daily for 2 days thereafter. Brains were perfusion-fixed on the third day. Planimetric analysis of hemotoxylin and eosin-stained coronal brain sections documented a cortical infarct averaging 72.9 +/- 33.3 mm3 (mean +/- SD) in untreated rats. Cortical infarct volume was reduced by 48% (to 37.6 +/- 27.6 mm3) when therapy was initiated 1 hour postischemia (p less than 0.05). When treatment was deferred to 2 hours postichemia, mean cortical infarct volume was reduced by 34%, but this difference did not attain statistical significance. Infarct volume in rats with treatment initiated at 3 hours postischemia was indistinguishable from that in controls. Striatal infarct volume was similar in all groups. These results document a postischemic therapeutic window of cerebroprotection for (S)-emopamil lying between 1 and 2 hours after middle cerebral artery occlusion.     

Prolonged but delayed postischemic hypothermia: a long-term outcome study in the rat middle cerebral artery occlusion model.

Delayed but prolonged hypothermia persistently decreases cell death and functional deficits after global cerebral ischemia in rodents. Postischemic hypothermia also reduces infarction after middle cerebral artery occlusion (MCAO) in rat. Because initial neuroprotection is sometimes transient and may not subserve functional recovery, especially on demanding tasks, the authors examined whether postischemic cooling would persistently reduce infarction and forelimb reaching deficits after MCAO. Male spontaneously hypertensive rats were trained to retrieve food pellets in a staircase test that measures independent forelimb reaching ability. Later, rats underwent 90 minutes of normothermic MCAO, through a microclip, or sham operation. In some rats, prolonged cooling (33 degrees C for 24 hours and then 35 degrees C for 24 hours) began 2.5 hours after the onset of ischemia (60 minutes after the start of reperfusion; n = 17 with subsequently 1 death) or sham procedures (n = 4), whereas untreated sham (n = 4) and ischemic (n = 16 with subsequently 1 death) rats maintained normothermia. An indwelling abdominal probe continually measured core temperature, and an automated fan and water spray system was used to produce hypothermia. One month later rats were reassessed in the staircase test over five days and then killed. The contralateral limb impairment in food pellet retrieval was completely prevented by hypothermia (P = 0.0001). Hypothermia reduced an infarct volume of 67.5 mm3 after untreated ischemia to 35.8 mm3 (P < 0.0001). These findings of persistent benefit encourage the clinical assessment of hypothermia.     

两次线栓法构建脑缺血耐受模型大鼠血脑屏障通透性改变与基质金属蛋白酶9的表达☆

背景：诸多研究证实,短暂性脑缺血预处理可诱导脑缺血耐受。然而,脑缺血耐受的内源性保护机制尚未明确。 目的：观察脑缺血预处理诱导脑缺血耐受大鼠再灌注不同时间窗血脑屏障通透性改变及基质金属蛋白酶9表达的变化。 方法：将Wistar大鼠随机分为3组,缺血预处理组采用线栓法阻塞大脑中动脉10 min建立局灶性缺血预处理模型,分别在缺血预处理后1,3,7,14,21 d进行再次缺血2 h;模型组不进行缺血预处理,假手术组不阻塞血管。于再灌注22 h进行神经功能检测,采用TTC染色测定脑梗死体积,通过测定渗出血管外的伊文思蓝含量来评价血脑屏障通透性的变化,免疫组织化学和原位杂交法检测基质金属蛋白酶9蛋白及mRNA的表达。 结果与结论：与模型组比较,缺血预处理组1,3,7 d亚组的神经功能评分、脑梗死体积、血脑屏障通透性、脑含水量以及基质金属蛋白酶9蛋白和mRNA表达均明显减小/降低(P < 0.05或P < 0.01),其中以3 d亚组降低最为明显。提示缺血预处理诱导了脑缺血耐受,预缺血诱导的血脑屏障通透性改变以及基质金属蛋白酶9表达减低在脑缺血耐受中发挥重要作用。     

Anti-monocyte chemoattractant protein-1 gene therapy protects against focal brain ischemia in hypertensive rats.

Monocyte chemoattractant protein-1 (MCP-1) is expressed in the ischemic cortex after focal brain ischemia and appears to exacerbate ischemic damage. The authors examined the effect of gene transfer of dominant negative MCP-1, called 7ND, 90 minutes after induction of focal brain ischemia in hypertensive rats. Adenoviral vectors encoding mutant MCP-1 (Ad7ND; n = 11), or Escherichia coli beta-galactosidase (AdlacZ; n = 17) as control were injected into the lateral ventricle of male spontaneously hypertensive rats. Both AdlacZ (n = 12) and Ad7ND (n = 6) administration provided transgene expression as early as 6 hours after injection and the expression further increased on day 1, followed by a sustained detection on day 5. Five days after ischemia, infarct volume (75 +/- 13 mm, n = 5, mean +/- SD) significantly reduced to 72% of control (104 +/- 22 mm3, n = 5, P < 0.05) by 7ND gene transfer. Numbers of leukocytes in the vessels (48.3 +/- 32.9/cm2) and macrophage/monocyte infiltration (475.2 +/- 125.5/mm2) of the infarct area in the Ad7ND group were significantly less than those measured in the AdlacZ group (143.8 +/- 72.1/cm2 and 671.8 +/- 125.5/mm2, P < 0.05, respectively). In summary, the postischemic gene transfer of dominant negative MCP-1 attenuated the infarct volume and infiltration of inflammatory cells, suggesting potential usefulness of the anti-MCP-1 gene therapy.