Progesterone administration during reperfusion, but not preischemia alone, reduces injury in ovariectomized rats.

Although progesterone is neuroprotective in traumatic brain injury, its efficacy in stroke is unclear. The authors determined whether there are infarction differences after middle cerebral artery occlusion (MCAO) in ovariectomized rats treated acutely with progesterone before MCAO or both pre- and postischemia. Rats received vehicle, 5 (P5), 10 (P10), or 20 (P20) mg/kg progesterone intraperitoneally 30 minutes before MCAO. In another cohort, animals received vehicle or 5 (P5R) mg/kg progesterone intraperitoneally 30 minutes before MCAO, at reperfusion initiation, and at 6-hour reperfusion. Animals underwent 2-hour MCAO by the intraluminal filament technique, followed by 22-hour reperfusion. Cortical (CTX) and caudate-putamen (CP) infarctions were determined by 2,3,5-triphenyltetrazolium chloride staining and digital image analysis. End-ischemic and early reperfusion regional cerebral blood flow (CBF) was measured by [ C]-iodoantipyrine quantitative autoradiography in vehicle- or progesterone (5 mg/kg)-treated rats. Cortical infarction (% contralateral CTX) was 31 +/- 30% (vehicle), 39 +/- 23% (P5), 41 +/- 14% (P10), and 28 +/- 20% (P20). Caudate-putamen infarction (% contralateral CP) was 45 +/- 37% (vehicle), 62 +/- 34% (P5), 75 +/- 17% (P10), and 52 +/- 30% (P20). In vehicle and P5R groups, CTX infarction was 37 +/- 20% and *20 +/- 17%, respectively (* < 0.05 from vehicle). In vehicle and P5R groups, CP infarction was 63 +/- 26% and 43 +/- 29%, respectively. End-ischemic regional CBF and CBF recovery during initial reperfusion was unaffected by progesterone treatment. These data suggest that progesterone administration both before MCAO and during reperfusion decreases ischemic brain injury.     

17beta-estradiol reduces stroke injury in estrogen-deficient female animals.

BACKGROUND AND PURPOSE: The importance of postmenopausal estrogen replacement therapy for stroke in females remains controversial. We previously showed that female rats sustain less infarction in reversible middle cerebral artery occlusion (MCAO) than their ovariectomized counterparts and that vascular mechanisms are partly responsible for improved tissue outcomes. Furthermore, exogenous estrogen strongly protects the male brain, even when administered in a single injection before MCAO injection. The present study examined the hypothesis that replacement of 17beta-estradiol to physiological levels improves stroke outcome in ovariectomized, estrogen-deficient female rats, acting through blood flow-mediated mechanisms. METHODS: Age-matched, adult female Wistar rats were ovariectomized and treated with 0, 25, or 100 microgram of 17beta-estradiol administered through a subcutaneous implant or with a single Premarin (USP) injection (1 mg/kg) given immediately before ischemia was induced (n=10 per group). Each animal subsequently underwent 2 hours of MCAO by the intraluminal filament technique, followed by 22 hours of reperfusion. Ipsilateral parietal cortex perfusion was monitored by laser-Doppler flowmetry throughout ischemia. Cortical and caudate-putamen infarction volumes were determined by 2,3, 5-triphenyltetrazolium chloride staining and digital image analysis. End-ischemic regional cerebral blood flow was measured in ovariectomized females with 0- or 25-microgram implants (n=4 per group) by (14)C-iodoantipyrine quantitative autoradiography. RESULTS: Plasma estradiol levels were 3.0+/-0.6, 20+/-8, and 46+/-10 pg/mL in the 0-, 25-, and 100-microgram groups, respectively. Caudate-putamen infarction (% of ipsilateral caudate-putamen) was reduced by long-term, 25-microgram estrogen treatment (13+/-4% versus 31+/-6% in the 0-microgram group, P<0.05, and 22+/-3% in the 100-microgram group). Similarly, cortical infarction (% of ipsilateral cortex) was reduced only in the 25-microgram group (3+/-2% versus 12+/-3% in the 0-microgram group, P<0.05, and 6+/-3% in the 100-microgram group. End-ischemic striatal or cortical blood flow was not altered by estrogen treatment at the neuroprotective dose. Infarction volume was unchanged by acute treatment before MCAO when estrogen-treated animals were compared with saline vehicle-treated animals. CONCLUSIONS: Long-term estradiol replacement within a low physiological range ameliorates ischemic brain injury in previously ovariectomized female rats. The neuroprotective mechanism is flow-independent, not through preservation of residual ischemic regional cerebral blood flow. Furthermore, the therapeutic range is narrow, because the benefit of estrogen in transient vascular occlusion is diminished at larger doses, which yield high, but still physiologically relevant, plasma 17beta-estradiol levels. Lastly, unlike in the male brain, single-injection estrogen exposure does not salvage ischemic tissue in the female brain. Therefore, although exogenous steroid therapy protects both male and female estrogen-deficient brain, the mechanism may not be identical and depends on long-term hormone augmentation in the female.     

NXY-059, a novel free radical trapping compound, reduces cortical infarction after permanent focal cerebral ischemia in the rat

Free radicals have gained wide acceptance as mediators of cerebral ischemic injury. It has previously been reported that a spin trap nitrone, alpha-phenyl-N-tert-butyl nitrone (PBN), can reduce infarct volumes in rats subjected to either permanent or transient focal cerebral ischemia. A recent study has demonstrated that NXY-059, a novel free radical trapping nitrone compound, has a neuroprotective effect against transient focal cerebral ischemia. This study was designed to determine the effect of NXY-059 in a rodent model of permanent focal cerebral ischemia. Male spontaneously hypertensive rats were subjected to permanent middle cerebral artery occlusion (MCAO) by placement of a microaneurysm clip on the middle cerebral artery (MCA). Animals were divided into three groups: (1) physiological saline given as a 1 ml/kg i.v. bolus administered 5 min post MCAO followed immediately by a continuous i.v. infusion of 0.5 ml/h of physiological saline for 24 h (n=10); (2) 30 mg/kg, 1 ml/kg, i.v. bolus of NXY-059 dissolved in physiological saline administered 5 min post MCAO followed immediately by a continuous i.v. infusion of 30 mg/kg/h, 0.5 ml/h, of NXY-059 for 24 h (n=9); (3) 60 mg/kg, 1 ml/kg, i.v. bolus of NXY-059 dissolved in physiological saline administered 5 min post MCAO followed immediately by a continuous i.v. infusion of 60 mg/kg/h, 0.5 ml/h, of NXY-059 for 24 h (n=12). Infarction was quantified after a survival period of 24 h. Differences in infarct volume were examined with one-way ANOVA following Dunnet's multiple comparison test. The percentage of cortical infarction in the saline control group was 22.6 +/- 6.8% (mean+/-S.D.) of contra-lateral hemisphere, and in the 30 mg/kg/h NXY-059-treated group was 17.4% +/- 6.8% (NS). Plasma concentration (microM/l) of NXY-059 in the 30 mg/kg/h group was 80.2 +/- 52.2 (n=9), while in the 60 mg/kg/h group plasma concentration (microM/l) of NXY-059 was 391.0 +/- 207.0 (n=10). Infarction in the 60 mg/kg/h NXY-059-treated group was significantly reduced (P=0.009) to 14.5 +/- 5%. Our preliminary data demonstrate that administration of NXY-059 (60 mg/kg/h for 24 h) ameliorates cortical infarction in rats subjected to permanent focal cerebral ischemia with 24 h survival.     

Neuroprotective FK506 does not alter in vivo nitric oxide production during ischemia and early reperfusion in rats.

BACKGROUND AND PURPOSE: Previous studies have demonstrated that the immunosuppressant FK506 provides neuroprotection in experimental brain injury and suggest that this action may be mediated by suppression of neuronal nitric oxide synthase activation that occurs after ischemic depolarization. We sought to determine whether FK506 reduces histological injury after middle cerebral artery occlusion (MCAO) in the rat and whether the neuroprotective effect is mediated via suppression of in vivo nitric oxide (NO) production during ischemia or early reperfusion. METHODS: Under controlled conditions of normoxia, normocarbia, and normothermia, halothane-anesthetized male Wistar rats were subjected to 2 hours of MCAO by the intraluminal occlusion technique in a blinded, randomized experimental trial. Ipsilateral parietal cortical laser-Doppler flowmetry was monitored throughout ischemia. Animals were randomly assigned to 4 pretreatment groups: intravenous FK506 0.3 mg/kg or 1. 0 mg/kg, vehicle (cremaphor), or an equivalent volume of saline administered 30 minutes before MCAO. Infarction volume was assessed by a triphenyltetrazolium chloride staining at 22 hours of reperfusion. In separate experiments, microdialysis probes were placed bilaterally into the striatum. Rats were perfused with artificial cerebrospinal fluid containing 3 micromol/L [14C]- L-arginine for 3 hours and then subjected to 2 hours of right MCAO. Intravenous 0.3 mg/kg FK506 or cremaphor was given 30 minutes before right MCAO. Right-left differences between [14C]-L-citrulline in the effluent were assumed to reflect differences in NO production. RESULTS: All values are mean+/-SE. FK506 at 0.3 mg/kg reduced infarction volume in cortex: 40+/-12 mm3 compared with saline (109+/-15 mm3) and cremaphor vehicle (148+/-23) (P<0.05). Striatal infarction was also reduced by low-dose FK506: 16+/-4 mm3 versus 36+/-4 mm3 and 34+/-4 mm3 in saline and vehicle groups, respectively (P<0.05). High-dose treatment reduced infarction volume in cortex (61+/-14 mm3, P<0.05 from saline and vehicle groups) and in striatum (22+/-5 mm3, P<0.05 from saline and vehicle groups). [14C]-L-citrulline recovery via microdialysis was markedly enhanced in ischemic compared with nonischemic striatum. However, ischemia-evoked [14C]-L-citrulline recovery was not different in FK506-treated rats compared with vehicle-treated animals. CONCLUSIONS: These data demonstrate that FK506 provides robust neuroprotection against transient focal cerebral ischemia in the rat. The mechanism of protection in vivo is not through attenuation of ischemia-evoked NO production during MCAO and early reperfusion.     

Effects of combined estrogen and progesterone on brain infarction in reproductively senescent female rats.

Recent data from the Women's Health Initiative have highlighted many fundamental issues about the utility and safety of long-term estrogen use in women. Current hormone replacement therapy for postmenopausal women incorporates progestin with estrogen, but it is uncertain if combined therapy provides major cerebrovascular risks or benefits to these women. No experimental animal stroke studies have examined combined hormone administration. The authors tested the hypothesis that combined hormone treatment reduces ischemic injury in middle-aged female rat brain. Reproductively senescent female rats underwent 2-hour middle cerebral artery occlusion (MCAO) followed by 22 hours reperfusion. Estrogen implants were placed subcutaneously at least 7 days before MCAO, and progesterone intraperitoneal injections were given 30 minutes before MCAO, at initiation, and at 6 hours of reperfusion. Rats received no hormone, a 25-microg estrogen implant, a 25-microg estrogen implant plus 5 mg/kg intraperitoneal progesterone, or 5 mg/kg intraperitoneal progesterone. Cortical, caudoputamen, and total infarct volumes were assessed by 2,3,5-triphenyltetrazolium chloride staining and digital image analysis at 22 hours reperfusion. Cortical and total infarct volumes, except in the acute progesterone-treated group, were significantly attenuated in all estrogen-alone and combined hormone-treated groups. There were no significant differences in caudoputamen infarct volumes in all hormone-treated groups as compared with untreated rats. These data have potential clinical implications relative to stroke for postmenopausal women taking combined hormone replacement therapy.     

Effects of RSR13, a synthetic allosteric modifier of hemoglobin, alone and in combination with dizocilpine, on outcome from transient focal cerebral ischemia in the rat

This study examined the effect of a pharmacologically induced rightward shift in the partial pressure of oxygen at which 50% of hemoglobin is saturated (P50) on outcome from transient focal cerebral ischemia in the rat. Halothane anesthetized rats (n=20 per group) were given saline or a single 15-min infusion of 150 mg/kg RSR13 (2-[4-[[3,5-dimethylanilino) carbonyl]methyl]phenoxy]-2-methylproprionic acid) intravenously before or 30 min after onset of 75 min of middle cerebral artery filament occlusion (MCAO). Seven days later, severity of hemiparesis and cerebral infarct size were examined. RSR13 alone did not significantly improve outcome. Conscious normothermic rats (n=12 per group) were also given RSR13 (150 mg/kg) or 0.9% NaCl intravenously and subjected to 75 min of MCAO with 7 days of recovery. Again, RSR13 alone did not significantly reduce infarct size or improve neurologic score. A dose-response curve for dizocilpine (MK-801) was then constructed in conscious normothermic rats subjected to 75 min of MCAO. Dizocilpine (0.5 mg/kg i.v.) caused a 90% reduction in mean infarct size while 0.25 mg/kg reduced infarct size by 48%. Other rats were then subjected to 75 min of MCAO after being given dizocilpine (0.25 mg/kg i.v.; n=18) or RSR13 (150 mg/kg i.v. )+dizocilpine (0.25 mg/kg i.v.; n=15). RSR13+dizocilpine resulted in smaller cortical infarct volume (8+/-14 mm3 vs. 34+/-37 mm3, p<0.02) and total cerebral infarct volume (46+/-28 mm3 vs. 81+/-60 mm3, p<0. 05) compared to dizocilpine alone, respectively. We conclude that a pre-ischemic peak increase in P50 of approximately 25 mmHg alone is insufficient to reduce focal ischemic injury, but may be advantageous when used in conjunction with other neuroprotective agents.     

Neuroprotection and glutamate attenuation by acetylsalicylic acid in temporary but not in permanent cerebral ischemia

To assess the effects of acetylsalicylic acid (ASA) on glutamate and interleukin-6 (IL-6) release in the striatum of rats suffering from cerebral ischemia, we used the microdialysis technique with probes implanted 2 h prior to stroke onset. A total of 36 rats were randomly assigned to either temporary (90 min, n=18) or permanent (n=18) middle cerebral artery occlusion (MCAO). Animals received either a bolus of 40 mg/kg ASA or saline as control 30 min after stroke onset. Permanent MCAO led to large infarct volumes with no differences between treatment with ASA (239.8+/-4.1 mm3) and saline (230.1+/-3.9 mm3, p=0.15). In contrast, ASA therapy in temporary ischemia (87.2+/-6.2 mm3) reduced infarct size significantly compared to placebo (155.6+/-4.8 mm3, p<0.0001). Only in temporary ischemia, ASA application reduced glutamate significantly at the time points 90, 120, and 150 min after MCAO. Pooled post-ischemic microdialysate concentrations of IL-6 in temporary MCAO were significantly higher after ASA treatment (215+/-81 pg/mL, p=0.0297) than in saline-treated rats (80+/-13 pg/mL). In the permanent MCAO group, no difference in IL-6 between the ASA (125+/-21 pg/mL) and saline group (68+/-34 pg/mL) was noted. No differences were seen for c-fos positive neurons in the penumbra and hippocampus between all groups. These results suggest that the neuroprotective effect of ASA is reflected by glutamate attenuation and IL-6 induction even if given after stroke onset, but only if reperfusion is achieved.     

Application of endovascular suture occlusion of middle cerebral artery in gerbils to obtain consistent infarction.

Middle cerebral artery occlusion (MCAO) by endovascular suture has gained increasing acceptance because it is relatively non-invasive and allows reperfusion. However, its application in rats has resulted in inconsistent infarction volumes which involve only the subcortex or subcortex plus some cortex. In order to eliminate this drawback, we applied the intraluminal suture occlusion of MCA to gerbils that have an incomplete Circle of Willis. MCAO was induced by inserting an endovascular 5-0 nylon suture with a blunted tip into the Circle of Willis. Animals were divided into two groups: permanent MCAO for 24 h (n = 8) and transient MCAO for 3 h with 21 h reperfusion (n = 8). The corrected infarction volume in the permanent MCAO group was 232 +/- 37 mm3 whereas it was 230 +/- 45 mm3 in the transient MCAO group. All animals in both groups had infarction in both cortex and subcortex. Results of this study show that endovascular suture occlusion of MCA can be easily applied in gerbils to obtain consistent infarction. This would allow both transient and permanent focal ischemia to be tested in the same model of ischemia.     

Effect of indomethacin on edema following single and repetitive cerebral ischemia in the gerbil

BACKGROUND AND PURPOSE: Repetitive periods of cerebral ischemia result in more severe injury than a single period of ischemia of similar total duration. We investigated the possibility of prostaglandin mediation of this increased injury by attempting to modify brain edema formation with indomethacin pretreatment. METHODS: Under halothane/N2O anesthesia, groups of gerbils underwent bilateral carotid occlusion to induce forebrain ischemia. Group I underwent a single 15-minute period of carotid occlusion. Group II underwent three 5-minute periods of occlusion at hourly intervals. Groups III and IV were similar to groups I and II, respectively, but received 0.2 mg/kg indomethacin before carotid occlusion. Cortical and cerebellar water and sodium contents were determined in control animals (n = 6) at time zero and in experimental animals 24, 48, and 72 hours after ischemia (n = 6-10 gerbils/group at each time point). RESULTS: Cortical water and sodium contents in group II peaked 48 hours after insult (82.15 +/- 0.31% and 420 +/- 14 meq/kg dry wt, respectively) and were significantly higher than control and group I values at both 24 and 48 hours. Cortical water did not change from control in group I animals. Indomethacin pretreatment significantly attenuated increases in water and sodium content seen at 48 hours in gerbils undergoing repetitive ischemia (peak 80.02 +/- 0.45% and 300 +/- 39 meq/kg dry wt), but did not affect mortality. CONCLUSIONS: Indomethacin lessens edema after repetitive cerebral ischemia, suggesting that elevations of cyclooxygenase products are responsible, at least in part, for severe brain edema following repetitive ischemia.     

Genetic hypertension and increased susceptibility to cerebral ischemia.

A review of the sensitivity of genetically hypertensive rats to cerebral ischemia was presented together with original data describing the systematic comparison of the effects of focal ischemia (permanent and temporary with reperfusion) performed in hypertensive and normotensive rats (i.e., blood pressures verified in conscious instrumented rats). Microsurgical techniques were used to isolate and occlude the middle cerebral artery (MCAO) of spontaneously hypertensive (SHR), Sprague-Dawley (SD) and Wistar Kyoto (WKY) rats at the level of the inferior cerebral vein. Following permanent (24 h) MCAO, persistent and similar decreases in local microvascular perfusion (i.e., to 15.6 +/- 1.7% of pre-MCAO levels) were verified in the primary ischemic zone of the cortex for all strains using Laser-Doppler flowmetry. A contralateral hemiplegia that occurred following MCAO, evidenced by forelimb flexion and muscle weakness, was greater in SHR (neurological grade = 2.0 +/- 0.1) than SD (1.0 +/- 0.4) or WKY (0.7 +/- 0.4) rats (N = 7-9, p less than 0.05). SHR also exhibited sensory motor deficits following MCAO compared to sham-operation, with decreased normal placement response of the hindlimb (% normal = 20 vs. 83, N = 23-30, p decreased rota-rod (41 +/- 7 vs. 126 +/- 19 on rod, N = 10-15, p less than 0.05) and balance beam (25 +/- 5 vs. 116 +/- 29 s on beam, N = 5-7, p less than 0.05) performance. However, an index of general motor activity was not affected by permanent MCAO. Triphenyltetrazolium-stained forebrain tissue analyzed by planimetry revealed a significantly larger and more consistent cortical infarction in SHR (hemispheric infarction = 27.9 +/- 1.5%) compared to SD (15.4 +/- 4.1%) and WKY (4.0 +/- 2.4%) rats (N = 7-9, p less than 0.05), occupying predominantly the frontal and parietal areas. Also, a significant degree of ipsilateral hemispheric swelling (4.6 +/- 0.9%, N = 7-9, p less than 0.05) and increased brain water content (78.4 +/- 0.3% to 80.4 +/- 0.2%, N = 8-9, p less than 0.05) was identified in SHR that was not observed in SD or WKY rats. A novel model of temporary MCAO also was evaluated in the hypertensive and normotensive rat strains. Initially, the effect of increasing MCAO-time followed by 24 h reperfusion in SHR was studied. During temporary MCAO (20 to 300 min), persistent and stable decreases in local microvascular perfusion (i.e., to 15-20% of pre-MCAO levels) were verified in the primary ischemic zones of the cortex.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

Estrogen blocks the cardiovascular and autonomic changes following vagal stimulation in ovariectomized rats

The current investigation examines the effect of acute and chronic estrogen administration on baroreflex sensitivity and autonomic tone following 2 h of vagal afferent stimulation in ovariectomized female rats. Female Sprague-Dawley rats were ovariectomized and supplemented daily for 7 days with either estrogen (OVX-E2; 0.5 microg/kg; s.c.) or saline (OVX-S; 0.9%; s.c.). On the 8th day the animals were anaesthetized (sodium thiobutabarbitol; 100 mg/kg) and instrumented for recording blood pressure, heart rate and efferent vagal and renal nerve activities. The baroreflex was evoked using intravenous injection of various doses of phenylephrine hydrochloride (0.025, 0.05+/-0.1 mg/kg). Electrical stimulation of vagal afferents for 2 h produces autonomic imbalance characterized by sympathoexcitation and parasympathetic withdrawal. This protocol of vagal stimulation produced a significant increase in renal nerve activity (from 20+/-6 to 140+/-20 spikes/2 s) and decreases in both vagal nerve activity (from 22+/-3 to 10+/-2 spikes/2 s) and baroreflex sensitivity (from 0.55+/-0.05 to 0.3+/-0.05) in OVX-S female rats. However. vagal stimulation had no effect on baroreflex sensitivity or autonomic nerve activities in OVX-E2 rats. Administration of a single, bolus dose of estrogen (1 x 10(-2) mg/kg) to OVX-S rats immediately prior to termination of vagal stimulation blocked the changes in autonomic nerve activities and baroreflex sensitivity previously observed. These results suggest that both chronic and acute estrogen supplementation may provide resistance to the autonomic disturbances associated with visceral afferent activation.     

The nitroxide antioxidant tempol is cerebroprotective against focal cerebral ischemia in spontaneously hypertensive rats

Free radicals appear to participate in the final common pathway of neuronal death in ischemia and may therefore be an adequate target for therapy. Tempol is a nitroxide antioxidant with proven protective efficacy in several animal models, including myocardial ischemia, that has not been previously tested in models of permanent cerebral ischemia. Spontaneously hypertensive rats underwent permanent middle cerebral artery occlusion (PMCAO). Following dose-response and time-window-finding experiments rats were given vehicle or tempol (50 mg/kg) subcutaneously 1 h after PMCAO (n = 10/group). Five animals in each group were evaluated with a motor scale 24 h after the infarct and were then sacrificed and the injury volume was measured. The remaining animals were examined daily with the motor scale and also with a Morris water maze test on days 26-30 after PMCAO and sacrificed on day 30. Motor scores at all time points examined were significantly better in the tempol-treated animals (P < 0.05 for all). Significantly better performance in the water maze test for performance on days 26-30 was noted in the tempol group compared with the vehicle-treated group (P < 0.05). Injury volumes at days 1 and 30 were significantly reduced in the tempol group (9.83 +/- 1.05 vs 19.94 +/- 1.43% hemispheric volume, P = 0.0009, and 13.2 +/- 2.97 vs 24.4 +/- 2.38% hemispheric volume, P = 0.02, respectively). In conclusion, treatment with tempol led to significant motor and behavioral improvement and reduced injured tissue volumes both in the short and in the long term after stroke.     

山楂叶总黄酮对大鼠脑缺血再灌注后基质金属蛋白酶-9表达的影响

目的研究山楂叶总黄酮对大鼠脑缺血再灌注损伤中基质金属蛋白酶-9(MMP-9)表达的影响。方法雄性Wistar大鼠,随机分为假手术组、缺血再灌注组及山楂叶总黄酮组(60、30、15mg/kg),线栓法建立大鼠大脑中动脉闭塞局灶性脑缺血再灌注模型。观察再灌注3d后脑梗死面积,通过免疫组织化学染色方法测定MMP-9的表达。结果山楂总黄酮组(60、30mg/kg)的脑梗死面积较缺血再灌注组明显减少,MMP-9的表达明显低于缺血再灌注组,P<0.01。结论山楂叶总黄酮能明显地减少脑梗死的面积,降低MMP-9的表达,发挥脑保护作用。     

NGF、BDNF在脑梗死及糖尿病合并脑梗死大鼠脑中的表达

目的探讨神经生长因子(nerve growth factorNGF)、脑源性神经营养因子(brain-derived neu— rotropic factor,BDNF)在大鼠单纯性脑梗死时脑中的表达情况及糖尿病对它的影响。方法将SD大鼠分成对照组、单纯脑梗死组和糖尿病合并脑梗死组,采用线栓法制作大脑中动脉闭塞(MCAO)模型,2％链脲佐菌素按60mg／ kg腹腔注射制作糖尿病模型,用免疫组化SABC方法检测脑组织NGF、BDNF蛋白表达。结果正常脑组织有少量NGF、BDNF的表达。局灶性脑缺血后24h,NGF、BDNF在梗死的缺血边缘区均有表达上调,其中单纯脑梗死比糖尿病合并脑梗死的NGF、BDNF表达更为明显。NGF、BDNF表达见于缺血边缘区神经元及胶质细胞的胞浆。结论 NGF、BDNF在脑梗死时表达上调是机体对缺血性损伤的内源性代偿机制。糖尿病合并脑梗死时NGF、BD- NF表达上调的不明显,NGF、BDNF表达不足可能与糖尿病加重梗死有关。     

Effects of ketamine on outcome from temporary middle cerebral artery occlusion in the spontaneously hypertensive rat.

This experiment evaluated the potential for ketamine HCl, a non-competitive glutamate antagonist, to minimize injury resulting from temporary focal cerebral ischemia. Male spontaneously hypertensive rats were randomly assigned to receive either ketamine (n = 13) or halothane anesthesia (n = 12) during 2 h of reversible middle cerebral artery occlusion (MCAO). Ketamine was administered as a 50 mg/kg i.v. loading dose followed by a continuous 1.25 mg/kg/min i.v. infusion beginning 25 min prior to ischemia and continued until 30 min after reperfusion. An additional group of rats (ketamine-shams, n = 8) underwent craniectomy and ketamine administration (as above) but the middle cerebral artery was not ligated. Physiologic values were similar between groups with the exception of plasma glucose which was elevated in the halothane-MCAO group. After 4 days recovery, rats in all groups were neurologically evaluated. There were no differences between the two groups undergoing MCAO for neurologic grading or open field behavior, although both groups performed worse than did ketamine-shams (P less than 0.05). In contrast, motor performance revealed more severe deficits in the ketamine-MCAO rats vs either the halothane-MCAO or ketamine-sham groups (P less than 0.05). Cerebral infarct volume was then planimetrically measured after triphenyl tetrazolium chloride (TTC) staining of fresh brain sections. Mean +/- S.D. infarct volume was not different between the halothane-MCAO (134 +/- 51 mm3) and ketamine-MCAO (131 +/- 64 mm3) groups. Seven of 8 sham rats were free of TTC demarcated injury and in the remaining rat injury was minimal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuroprotective effects of the CRF1 antagonist R121920 after permanent focal ischemia in the rat.

The neuroprotective effects of a systemically active, highly selective, corticotropin-releasing factor-1 (CRF1) receptor antagonist, R121920 ((7-(dipropylamino)-2,5-dimethyl-3- [2-(dimethylamino)-5-pyridyl] pyrazolo [1,5-a] pyrimidine), was assessed in two rat models of permanent focal cerebral ischemia, where the middle cerebral artery (MCA) was occluded either through the subtemporal approach or using the intraluminal suture technique. R121920 rapidly crossed the blood-brain barrier after intravenous (IV) bolus administration (10 mg/kg), with peak brain concentrations at 5 minutes (2.26 +/- 0.40 microg/mL), which were approximately 2-fold greater than those in plasma (0.98 +/- 0.24 microg/mL). Treatment with R121920 (10 mg/kg IV followed by 5 mg/kg subcutaneously at hourly intervals for 4 hours) significantly (P < 0.001) reduced total (by 40%) and cortical (by 37%) infarct volume at 24 hours after subtemporal MCA occlusion (MCAO). In the intraluminal suture MCAO model, IV administration of R121920 (10 mg/kg) at the time of ischemia onset (and at multiple times thereafter) reduced both hemispheric infarct volume (by 34%, P < 0.001) and brain swelling (by 50%, P < 0.001) when assessed at 24 hours. In this model of focal ischemia, significant reduction (P < 0.05) in both outcome measures was obtained when R121920 administration was delayed up to 1 hour after MCAO. These results further define the antiischemic properties of selective CRF 1 antagonists in two experimental models of permanent focal cerebral ischemia.     

Cerebroprotective action of a Na+/Ca2+ channel blocker NS-7. II. Effect on the cerebral infarction, behavioral and cognitive impairments at the chronic stage of permanent middle cerebral artery occlusion in rats

We have previously shown that NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride] reduces the size of cerebral infarction measured by 2,3,5-triphenyltetrazolium chloride staining at 48 h after permanent middle cerebral artery occlusion (MCAO) in rats. To determine whether NS-7 improves the pathological and behavioral changes at the chronic stage of MCAO, the effect of this compound on the cerebral infarction as well as the neurological and cognitive impairments was investigated 7 days after MCAO. Single or five daily injections of NS-7 (0.125-0.5 mg/kg, i.v.) significantly reduced the infarct volume and improved the neuronal dysfunction including the hind leg paralysis, walking disability and motor incoordination, and the deficit of passive avoidance task, although the neuroprotective efficacy was not different among these dosing regimens. On the other hand, the effects of single versus repeated injections of NS-7 at 0.1 or 0.2 mg/kg on the neurological symptoms were compared at 4 weeks after MCAO. At a lower dose, repeated but not single injection of NS-7 significantly improved the neurological symptoms, although the single injection was effective at a higher dose. From these findings, it is suggested that NS-7 reverses the behavioral and cognitive dysfunction observed at the chronic stage of cerebral ischemia by suppressing the cerebral infarction.     

丹参多酚酸盐对缺血再灌注损伤大鼠脑组织BDNF和GDNF的影响

目的观察丹参多酚酸盐对大鼠局灶性脑缺血再灌注损伤后脑组织内脑源性神经营养因子（BDNF）及胶质源性神经营养因子（GDNF）表达的影响,探讨其神经保护作用的机制。方法线栓法制作大鼠大脑中动脉闭塞再灌注损伤模型,SD大鼠随机分为正常对照组、缺血再灌注组、丹参多酚酸盐低剂量治疗组（10mg／kg）和丹参多酚酸盐高剂量治疗组（30mg／kg）,观察各组大鼠的行为学改变,测定脑梗死体积,ELISA法检测脑组织中BDNF和GDNF的含量。结果与缺血再灌组比较,丹参多酚酸盐可以显著降低大鼠神经损伤行为学评分,减少脑梗死体积,增加脑组织内BDNF和GDNF的含量,且呈剂量依赖性。结论丹参多酚酸盐对脑缺血再灌注损伤有明显的保护作用,其机制与促进脑组织合成BDNF及GDNF有关。     

The effects of a competitive NMDA receptor antagonist (CGS-19755) on cerebral blood flow and pH in focal ischemia.

We report the effects of intravenous infusion of CGS-19755, a potent competitive N-methyl-D-aspartate (NMDA) antagonist, on local cerebral pH (LCpH) and local CBF (LCBF) in rats with occluded left middle cerebral and common carotid arteries. LCpH and LCBF were determined simultaneously by a double-label autoradiographic technique 4 h after vascular occlusion in three groups: no treatment, carrier infused, and a group receiving CGS-19755 at 10 mg/kg bolus immediately after occlusion followed by infusion at 5 mg kg-1 h-1 for 4 h. Compared with rats receiving carrier, several cortical structures on the side of occlusions showed significantly higher CBF in rats receiving CGS-19755. This drug also corrected the pH in several left cortical structures to values significantly higher than in the rats receiving carrier. The correction in LCpH was not limited to those regions showing significant elevations in LCBF. In the nonoccluded hemisphere, CGS-19755 significantly increased the hemispheric mean blood flow from 122 +/- 17 to 221 +/- 64 ml 100 g-1 min-1 (mean +/- SD of all structures, p less than 0.01) without any changes in LCpH. Cortical but not basal ganglia infarct volume was significantly smaller in rats receiving CGS-19755 than in the carrier-treated group. These results suggest that, at least partially, the neuroprotective effect of CGS-19755 in ischemia may be related to changes in CBF and pH in addition to its antagonist effect on the NMDA receptor.