Protective effect of resveratrol against oxidative stress in middle cerebral artery occlusion model of stroke in rats

Free radicals have been implicated in neuronal injury during ischemia reperfusion in stroke. Trans resveratrol, a potent antioxidant, polyphenolic compound found in grapes and wines has recently been shown to have neuroprotective activity against oxidative stress in in vitro studies. In the present study the effect of chronic treatment of trans resveratrol was evaluated in focal ischemia induced by middle cerebral artery [MCA] occlusion in rats. Male Wistar rats were pretreated with trans resveratrol 20 mg/kg i.p. for 21 days and were subjected to focal ischemia by occlusion of MCA using intraluminal thread. After two hours of MCA occlusion reperfusion was allowed by retracting the thread. Animals were assessed for motor performance after 24 hours and subsequently rats were sacrificed for estimation of markers of oxidative stress [malondialdehyde [MDA] and reduced glutathione] and for evaluation of volume of infarction. Control group received vehicle and similar protocol was followed. Significant motor impairment, with elevated levels of MDA and reduced glutathione was observed in the vehicle treated MCA occluded rats. Treatment with trans resveratrol prevented motor impairment, rise in levels of MDA and reduced glutathione and also significantly decreased the volume of infarct as compared to control. The study provides first evidence of effectiveness of trans resveratrol in focal ischemia most probably by virtue of its antioxidant property.     

莫诺苷对大鼠局灶性脑缺血再灌注损伤神经功能的影响

目的观察中药山茱萸的有效成分莫诺苷对大鼠局灶性脑缺血再灌注后神经功能的影响。方法Wistar雄性大鼠随机分为假手术组、模型组、莫诺苷小剂量组（30 mg/kg）、莫诺苷中剂量组（90 mg/kg）、莫诺苷大剂量组（270 mg/kg）、维生素E（VE）（35 mg/kg）,采用线栓法制作大鼠局灶性脑缺血再灌注模型,缺血30 min后再灌注3 d,应用Zea Longa法、爬网格、平行木、吊绳、Ludmila Belayev 12分评分法,观察莫诺苷对神经功能缺损的改善作用。结果与模型组比较,莫诺苷给药组（小、中、大剂量）Zea Longa法评分均差异极显著（P〈0.01）;与模型组比较,莫诺苷给药组（小、中、大剂量）吊绳法评分均差异极显著（P〈0.01）;Ludmila Belayev 12分评分法评分与模型组比较,莫诺苷大剂量组差异极显著（P〈0.001）,中剂量组差异极显著（P〈0.01）。结论莫诺苷对局灶性脑缺血再灌注模型大鼠有改善行为学评分的作用。     

Effect of endothelin antagonist (TAK-044) on cerebral ischemic volume, oxidative stress markers and neurobehavioral parameters in the middle cerebral artery occlusion model of stroke in rats

Stroke causes brain injury in millions of people world wide each year. Despite the enormity of problem, currently there is no established therapy, which can restore the blood flow at infracted area and also improve the neurological deficit. The present study was carried out to investigate the effect of an endothelin antagonist (TAK-044) in middle cerebral artery (MCA) occlusion model of acute ischemic stroke in rats. Male Wistar rats were pretreated with TAK-044 (5 mg/kg, i.p.) for 7 days and thereafter subjected to focal ischemia by occlusion of MCA using intraluminal thread for two hours. 30 min after reperfusion the animals were subjected to diffusion-weighted imaging (DWI) for assessment of protective effect. Twenty-four hours later the motor performance was tested and subsequently the animals were sacrificed for estimation of markers of oxidative stress; malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD). Control group received vehicle (saline) and similar experimental protocol was followed. In the TAK-044 pretreated group, percent hemispheric lesion area (% HLA) in DWI was significantly attenuated 17.5 +/- 0.5% as compared to control group 61.2 +/- 5.9%. Significant motor impairment, with significant elevated levels of MDA, decrease in GSH and SOD were observed in the vehicle treated MCA occluded rats. Pretreatment with TAK-044 prevented the motor impairment and significantly reversed the changes in markers of oxidative stress (MDA, GSH and SOD). In addition to well-known vasodilatory effect, TAK-044 has recently been documented to have antioxidant and anti-inflammatory properties. These effects can contribute to the protection afforded by TAK-044 in the present study.     

Melatonin reduces cerebral edema formation caused by transient forebrain ischemia in rats

Reduction of cerebral edema, an early symptom of ischemia, is one of the most important remedies for reducing subsequent chronic neural damage in stroke. Melatonin, a metabolite of tryptophan released from the pineal gland, has been found to be effective against neurotoxicity in vitro. The present study was aimed to demonstrate the effectiveness of melatonin in vivo in reducing ischemia-induced edema using magnetic resonance imaging (MRI). Rats were subjected to middle cerebral artery (MCA) occlusion/reperfusion surgery. Melatonin was administered twice (6.0 mg/kg, p.o.): just prior to 1 h MCA occlusion and 1 day after the surgery. T2-weighted multislice spin-echo images were acquired 1 day after the surgery. Increases in T2-weighted signals in ischemic sites of the brain were clearly observed after MCA occlusion. The signal increase was found mainly in the striatum and in the cerebral cortex in saline-treated control rats. In the melatonin-treated group, the total volume of cerebral edema was reduced by 45.3% compared to control group (P < 0.01). The protective effect of melatonin against cerebral edema was more clearly observed in the cerebral cortex (reduced by 56.1%, P < 0.01), while the reduction of edema volume in the striatum was weak (reduced by 23.0%). The present MRI study clearly demonstrated that melatonin is effective in reducing edema formation in ischemic animals in vivo, especially in the cerebral cortex. Melatonin may be highly useful in preventing cortical dysfunctions such as motor, sensory, memory, and psychological impairments.     

UPEI-100, a conjugate of lipoic acid and apocynin, mediates neuroprotection in a rat model of ischemia/reperfusion

Previous work in our laboratory has provided evidence that preadministration of apocynin and lipoic acid at subthreshold levels for neuroprotection enhanced the neuroprotective capacity when injected in combination. Therefore, the present investigation was designed to determine whether a co-drug consisting of lipoic acid and apocynin functional groups bound by a covalent bond, named UPEI-100, is capable of similar efficacy using a rodent model of stroke. Male rats were anesthetized with Inactin (100 mg/kg iv), and the middle cerebral artery was occluded for 6 h or allowed to reperfuse for 5.5 h following a 30-min occlusion (ischemia/reperfusion, I/R). Preadministration of UPEI-100 dose-dependently decreased infarct volume in the I/R model (P < 0.05), but not in the middle cerebral artery occlusion model of stroke. Using the optimal dose, we then injected UPEI-100 during the stroke or at several time points during reperfusion, and significant neuroprotection was observed when UPEI-100 was administered up to 90 min following the start of reperfusion (P < 0.05). A time course for this neuroprotective effect showed that UPEI-100 resulted in a decrease in infarct volume following 2 h of reperfusion compared with vehicle. The time course of this neuroprotective effect was also used to study several mediators along the antioxidant pathway and showed that UPEI-100 increased the level of mitochondrial superoxide dismutase and oxidized glutathione and decreased a marker of lipid peroxidation due to oxidative stress (HNE-His adduct formation). Taken together, the data suggest that UPEI-100 may utilize similar pathways to those observed for the two parent compounds; however, it may also act through a different mechanism of action.     

Edaravone ameliorates oxidative stress associated cholinergic dysfunction and limits apoptotic response following focal cerebral ischemia in rat

Stroke is a life-threatening disease with major cause of mortality and morbidity worldwide. The neuronal damage following cerebral ischemia is a serious risk to stroke patients. Oxidative stress and apoptotic damage play an important role in cerebral ischemic pathogenesis and may represent a target for treatment. The objective of this study was to test the hypothesis that administration of edaravone (Edv) maintains antioxidant status in brain, improves the cholinergic dysfunction and suppresses the progression of apoptosis response in rat. To test this hypothesis, male Wistar rats were subjected to middle cerebral artery occlusion (MCAO) of 2 h followed by reperfusion for 22 h. Edv was administered (10 mg/kg bwt) intraperitoneally 30 min before the onset of ischemia and 1 h after reperfusion. After reperfusion, rats were tested for neurobehavioral activities and were sacrificed for the infarct volume, estimation of oxidative damage markers. Edv treatment significantly reduced ischemic lesion volume, improved neurological deficits, contended oxidative loads, and suppressed apoptotic damage. In conclusion, treatment with Edv ameliorated the neurological and histological outcomes with elevated endogenous anti-oxidants status as well as reduced induction of apoptotic responses in MCA occluded rat. We theorized that Edv is among the pharmacological agents that reduce free radicals and its associated cholinergic dysfunction and apoptotic damage and have been found to limit the extent of brain damage following stroke.     

Piperine suppresses cerebral ischemia–reperfusion-induced inflammation through the repression of COX-2, NOS-2, and NF-κB in middle cerebral artery occlusion rat model

The pathophysiological mechanisms leading to neuronal injury in middle cerebral artery occlusion (MCAO) model of cerebral stroke are complex and multifactorial that form the bases of behavioral deficits and inflammation mediated damage. The present study demonstrates the effect of piperine pretreatment (10 mg/kg b wt, once daily p.o. for 15 days) on cerebral ischemia-induced inflammation in male Wistar rats. The right middle cerebral artery was occluded for 2 h followed by reperfusion for 22 h. A maximum infarct volume (57.80 %) was observed in ischemic MCAO group. However, piperine administration prior to ischemia showed a significant reduction in infarct volume (28.29 %; p < 0.05) and neuronal loss (12.72 %; p < 0.01). As a result of piperine pretreatment, a significant improvement in behavioral outputs of MCAO rats (p < 0.05-0.01) was observed. Piperine successfully reduced the level of proinflammatory cytokines IL-1β, IL-6 and TNF-α, in ischemic group (p < 0.01). Ischemic group brain has shown edematous morphology with vacuolated architecture and pyknotic nuclei in H & E staining which was successfully ameliorated by piperine administration. Moreover, piperine also succeeded in lowering the expression of COX-2, NOS-2, and NF-κB (p < 0.01). Both cytosolic and nuclear NF-κB were down-regulated in ischemic group pre-administered with piperine (p < 0.01). The present study suggests that piperine is able to salvage the ischemic penumbral zone neurons by virtue of its anti-inflammatory property, thereby limiting ischemic cell death.     

L-丝氨酸对大鼠脑缺血/再灌注损伤保护作用时间窗的实验研究

目的：研究L-丝氨酸对大鼠脑缺血/再灌注损伤保护作用的时间窗,并对其作用机制进行初探。方法：SD雄性大鼠随机分为假手术组、对照组、L-丝氨酸3h治疗组、6h治疗组、12h治疗组、24h治疗组。采用大脑中动脉栓塞（MCAO）建立大鼠局灶性脑缺血模型,2h后拔出栓线形成再灌注,各组分别于术后相应的时间点给予L-丝氨酸200mg/kg腹腔注射2次,对照组注射等剂量的生理盐水,所有动物再灌注后48h观测神经行为学评分、脑梗死体积。另取假手术组、对照组、L-丝氨酸6h治疗组,分别测定MCAO后脑内超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量,炎症细胞因子TNF-α、IL-6水平以及观察细胞超微结构改变。结果：与对照组相比,术后3h、6h给予L-丝氨酸治疗能显著降低大鼠神经行为学评分,减少脑梗死体积（P〈0.01或P〈0.05）,12h仅能降低神经行为学评分（P〈0.05）,而24h与对照组间均无差异;L-丝氨酸能提高MCAO后脑内SOD活性,降低MDA以及TNF-α、IL-6的水平,同时改善细胞超微结构。结论：在一定时间窗内,L-丝氨酸对大鼠MCAO具有明显的神经保护作用,其机制可能与降低氧自由基损伤,减轻炎症反应有关。     

Propofol Protects Against Focal Cerebral Ischemia via Inhibition of Microglia-Mediated Proinflammatory Cytokines in a Rat Model of Experimental Stroke

Ischemic stroke induces microglial activation and release of proinflammatory cytokines, contributing to the expansion of brain injury and poor clinical outcome. Propofol has been shown to ameliorate neuronal injury in a number of experimental studies, but the precise mechanisms involved in its neuroprotective effects remain unclear. We tested the hypothesis that propofol confers neuroprotection against focal ischemia by inhibiting microglia-mediated inflammatory response in a rat model of ischemic stroke. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by 24 h of reperfusion. Propofol (50 mg/kg/h) or vehicle was infused intravenously at the onset of reperfusion for 30 minutes. In vehicle-treated rats, MCAO resulted in significant cerebral infarction, higher neurological deficit scores and decreased time on the rotarod compared with sham-operated rats. Propofol treatment reduced infarct volume and improved the neurological functions. In addition, molecular studies demonstrated that mRNA expression of microglial marker Cd68 and Emr1 was significantly increased, and mRNA and protein expressions of proinflammatory cytokines tumor necrosis factor-α, interleukin-1β and interleukin-6 were augmented in the peri-infarct cortical regions of vehicle-treated rats 24 h after MCAO. Immunohistochemical study revealed that number of total microglia and proportion of activated microglia in the peri-infarct cortical regions were markedly elevated. All of these findings were ameliorated in propofol-treated rats. Furthermore, vehicle-treated rats had higher plasma levels of interleukin-6 and C-reactive protein 24 h after MCAO, which were decreased after treatment with propofol. These results suggest that propofol protects against focal cerebral ischemia via inhibition of microglia-mediated proinflammatory cytokines. Propofol may be a promising therapeutic agent for the treatment of ischemic stroke and other neurodegenerative diseases associated with microglial activation.     

Candesartan Reduces the Hemorrhage Associated with Delayed Tissue Plasminogen Activator Treatment in Rat Embolic Stroke

We have previously reported that angiotensin receptor blockade reduces reperfusion hemorrhage in a suture occlusion model of stroke, despite increasing matrix metalloproteinase (MMP-9) activity. We hypothesized that candesartan will also decrease hemorrhage associated with delayed (6 h) tissue plasminogen activator (tPA) administration after embolic stroke, widening the therapeutic time window of tPA. Adult male Wistar rats were subjected to embolic middle cerebral artery occlusion (eMCAO) and treated with either candesartan (1 mg/kg) alone early at 3 h, delayed tPA (10 mg/kg) alone at 6 h, the combination of candesartan and tPA, or vehicle control. Rats were sacrificed at 24 and 48 h post-eMCAO and brains perfused for evaluation of neurological deficits, cerebral hemorrhage in terms of hemoglobin content, occurrence rate of hemorrhage, infarct size, tissue MMP activity and protein expression. The combination therapy of candesartan and tPA after eMCAO reduced the brain hemorrhage, and improved neurological outcome compared with rats treated with tPA alone. Further, candesartan in combination with tPA increased activity of MMP-9 but decreased MMP-3, nuclear factor kappa-B and tumor necrosis factor-α expression and enhanced activation of endothelial nitric oxide synthase. An activation of MMP-9 alone is insufficient to cause increased hemorrhage in embolic stroke. Combination therapy with acute candesartan plus tPA may be beneficial in ameliorating tPA-induced hemorrhage after embolic stroke.     

梓醇对大鼠脑缺血再灌注损伤的保护作用研究

目的:探讨梓醇对缺血再灌注大鼠脑损伤后的保护作用.方法:采用传统大脑中动脉阻塞(MCAO)方法制备大鼠局灶性缺血模型,根据随机数字表法将SD大鼠分为MCAO组、对照组(vehicle组)及梓醇处理组(catalpol组),缺血再灌注48 h后观察各组大鼠神经功能学评分和脑梗死容积.分别于术前、术后6h、24 h、48 h取大鼠脑组织样本,检测匀浆中谷胱甘肽过氧化物酶(GSH-PX)和丙二醛(MDA)的变化情况.结果:与vehicle组和MCAO组相比,catalpol处理组神经功能学评分降低(P＜0.05);其梗死容积较小(P＜0.05).组织匀浆结果显示catalpol处理组脑匀浆中GSH-PX活力升高,MDA含量下降(P＜0.05).结论:梓醇可能通过降低脑内自由基水平、控制脂质过氧化程度,对缺血再灌注引起的大鼠脑损伤产生神经保护作用.     

Synergistic Effect of Selenium and Melatonin on Neuroprotection in Cerebral Ischemia in Rats

The synergistic scavenger effects of selenium and melatonin collectively we called Se-Mel was studied on the prevention of neuronal injury induced by ischemia/reperfusion. Male Wistar rats were treated with sodium selenite (0.1 mg/kg, i.p.) and melatonin (10 mg/kg, i.p.) 30 min before the middle carotid artery occlusion (MCAO) and immediately after MCAO to male Wistar rats and was continued for 3 days once daily at the interval of 24 h. Behavioral activity (spontaneous motor activity and motor deficit) was improved in Se-Mel-treated rats as compared to MCAO group rats. The level of glutathione and the activity of antioxidant enzymes was depleted significantly while the content of thiobarbituric acid reactive substances, protein carbonyl, and nitric oxide radical (NO^·) was increased significantly in MCAO group. Systemic administration of Se-Mel ameliorated oxidative stress and improves ischemia/reperfusion-induced focal cerebral ischemia. Se-Mel also inhibited inducible nitric oxide synthase expression in Se-Mel+MCAO group as compared to MCAO group rats. Thus, Se-Mel has shown an excellent neuroprotective effect against ischemia/reperfusion injury through an anti-ischemic pathway. In conclusion, we demonstrated that the pretreatment with Se-Mel at the onset of reperfusion, reduced post-ischemic damage, and improved neurological outcome following transient focal cerebral ischemia in male Wistar rat.     

Treadmill Pre-Training Ameliorates Brain Edema in Ischemic Stroke via Down-Regulation of Aquaporin-4: An MRI Study in Rats

Objective

Treadmill pre-training can ameliorate blood brain barrier (BBB) dysfunction in ischemia-reperfusion injury, however, its role in ischemic brain edema remains unclear. This study assessed the neuroprotective effects induced by treadmill pre-training, particularly on brain edema in transient middle cerebral artery occluded model.

Methods

Transient middle cerebral artery occlusion to induce stroke was performed on rats after 2 weeks of treadmill pre-training. Magnetic resonance imaging (MRI) was used to evaluate the dynamic impairment of cerebral edema after ischemia-reperfusion injury. In addition, measurements of wet and dry brain weight, Evans Blue assay and Garcia scores were performed to investigate the cerebral water content, BBB permeability and neurologic deficit, respectively. Moreover, during ischemia-reperfusion injury, the expression of Aquaporin 4 (AQP4) was detected using immunofluorescence and Western bloting analyses.

Results

Treadmill pre-training improved the relative apparent diffusion coefficient (rADC) loss in the ipsilateral cortex and striatum at 1 hour and 2.5 hours after cerebral ischemia. In the treadmill pre-training group, T2W1 values of the ipsilateral cortex and striatum increased less at 7.5 hours, 1 day, and 2 days after stroke while the brain water content decreased at 2 days after ischemia. Regarding the BBB permeability, the semi-quantitative amount of contrast agent leakage of treadmill pre-training group significantly decreased. Less Evans Blue exudation was also observed in treadmill pre-training group at 2 days after stroke. In addition, treadmill pre-training mitigated the Garcia score deficits at 2 days after stroke. Immunofluorescence staining and Western blotting results showed a significant decrease in the expression of AQP4 after treadmill ischemia following pre-training.

Conclusions

Treadmill pre-training may reduce cerebral edema and BBB dysfunction during cerebral ischemia/reperfusion injury via the down-regulation of AQP4.     

Effects of iloprost on visual evoked potentials and brain tissue oxidative stress after bilateral common carotid artery occlusion

Effects of iloprost on visual evoked potentials and oxidant/antioxidant status were evaluated after bilateral carotid artery occlusion. There were three experimental groups; Sham (S) group (n=10), bilateral common carotid artery occluded (BCCAO) group (n=10) and after bilateral common carotid artery occlusion, iloprost-treated (BCCAOI) group (n=10). Iloprost was administered (0.5ng/kg/day) for 10 days by intraperitoneal injection. N(2) and P(2) latencies (millisecond) and N(2)-P(2) (microV) amplitudes were recorded 10 days after operation for evaluating VEPs. The rats were sacrificed by decapitation immediately after recording of VEPs. Malondialdehyte (MDA), glutathione (GSH), Cu-Zn superoxide dysmutase (SOD) were studied spectrophotometricly. After BCCAO, MDA levels were increased, GSH and Cu-Zn SOD levels were decreased significantly, and abnormal VEPs parameters were observed. Iloprost treatment after BCCAO decreased MDA and increased GSH levels significantly. Low Cu-Zn SOD levels and impaired VEPs remained after iloprost treatment. Iloprost treatment may protect the brain tissue from oxidative damage during cerebral hypoperfusion.     

Propensity of <Emphasis Type="Italic">Withania somnifera</Emphasis> to Attenuate Behavioural,Biochemical, and Histological Alterations in Experimental Model of Stroke

The present study was designed to evaluate the beneficial effects of Withania somnifera (WS) pre-supplementation on middle cerebral artery occlusion (MCAO) model of ischemic stroke. Ischemic stroke was induced in the rats by inserting intraluminal suture for 90 min, followed by reperfusion injury for 24 h. The animals were assessed for locomotor functions (by neurological deficit scores, narrow beam walk and rotarod test), cognitive and anxiety-like behavioural functions (by morris water maze and elevated plus maze test). MCAO animals showed significant impairment in locomotor and cognitive functions. Neurobehavioural changes were accompanied by decreased acetylcholinesterase activity, increased oxidative stress in terms of enhanced lipid peroxidation and lowered thiol levels in the MCAO animals. In addition, MCAO animals had cerebral infarcts and the presence of pycnotic nuclei. Single-photon emission computerized tomography (SPECT) of MCAO animals revealed a cerebral infarct as a hypoactive area. On the other hand, pre-supplementation with WS (300 mg/kg body weight) for 30 days to MCAO animals was effective in restoring the acetylcholinesterase activity, lipid peroxidation, thiols and attenuated MCAO induced behavioural deficits. WS significantly reduced the cerebral infarct volume and ameliorated histopathological alterations. Improved blood flow was observed in the SPECT images from the brain regions of ischemic rats pre-treated with WS. The results of the study showed a protective effect of WS supplementation in ischemic stroke and are suggestive of its potential application in stroke management.     

Melatonin renders neuroprotection by protein kinase C mediated aquaporin-4 inhibition in animal model of focal cerebral ischemia

Aim

Aquaporin-4(AQP4) expression in the brain with relation to edema formation following focal cerebral ischemia was investigated. Studies have shown that brain edema is one of the significant factors in worsening stroke outcomes. While many mechanisms may aggravate brain injury, one such potential system may involve AQP4 up regulation in stroke patients that could result in increased edema formation. Post administration of melatonin following ischemic stroke reduces AQP4 mediated brain edema and confers neuroprotection.

Materials and methods

An in-silico approach was undertaken to confirm effective melatonin-AQP4 binding. Rats were treated with 5 mg/kg, i.p. melatonin or placebo at 30 min prior, 60 min post and 120 min post 60 min of middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. Rats were evaluated for battery of neurological and motor function tests just before sacrifice. Brains were harvested for infarct size estimation, water content measurement, biochemical analysis, apoptosis study and western blot experiments.

Key findings

Melatonin at 60 min post ischemia rendered neuroprotection as evident by reduction in cerebral infarct volume, improvement in motor and neurological deficit and reduction in brain edema. Furthermore, ischemia induced surge in levels of nitrite and malondialdehyde (MDA) were also found to be significantly reduced in ischemic brain regions in treated animals. Melatonin potentiated intrinsic antioxidant status, inhibited acid mediated rise in intracellular calcium levels, decreased apoptotic cell death and also markedly inhibited protein kinase C (PKC) influenced AQP4 expression in the cerebral cortex and dorsal striatum.

Significance

Melatonin confers neuroprotection by protein kinase C mediated AQP4 inhibition in ischemic stroke.     

Evaluation of the middle cerebral artery occlusion techniques in the rat by in-vitro 3-dimensional micro- and nano computed tomography

Background  

Animal models of focal cerebral ischemia are widely used in stroke research. The purpose of our study was to evaluate and compare the cerebral macro- and microvascular architecture of rats in two different models of permanent middle cerebral artery occlusion using an innovative quantitative micro- and nano-CT imaging technique.     

Performing Permanent Distal Middle Cerebral with Common Carotid Artery Occlusion in Aged Rats to Study Cortical Ischemia with Sustained Disability

Stroke typically occurs in elderly people with a range of comorbidities including carotid (or other arterial) atherosclerosis, high blood pressure, obesity and diabetes. Accordingly, when evaluating therapies for stroke in animals, it is important to select a model with excellent face validity. Ischemic stroke accounts for 80% of all strokes, and the majority of these occur in the territory of the middle cerebral artery (MCA), often inducing infarcts that affect the sensorimotor cortex, causing persistent plegia or paresis on the contralateral side of the body. We demonstrate in this video a method for producing ischemic stroke in elderly rats, which causes sustained sensorimotor disability and substantial cortical infarcts. Specifically, we induce permanent distal middle cerebral artery occlusion (MCAO) in elderly female rats by using diathermy forceps to occlude a short segment of this artery. The carotid artery on the ipsilateral side to the lesion was then permanently occluded and the contralateral carotid artery was transiently occluded for 60 min. We measure the infarct size using structural T2-weighted magnetic resonance imaging (MRI) at 24 hr and 8 weeks after stroke. In this study, the mean infarct volume was 4.5% ± 2.0% (standard deviation) of the ipsilateral hemisphere at 24 hr (corrected for brain swelling using Gerriet’s equation, n = 5). This model is feasible and clinically relevant as it permits the induction of sustained sensorimotor deficits, which is important for the elucidation of pathophysiological mechanisms and novel treatments.     

Sympathetically mediated hypermetabolic response to cerebral ischemia in the rat

Cerebral ischemia, induced in rats by occlusion of the middle cerebral artery resulted in infarcts affecting the basal ganglia and adjacent frontoparietal cortex. Resting oxygen consumption was similar for sham-operated and ischaemic rats immediately after surgery but was elevated in the latter group (peak value 18-21% above controls) 5-6 h post occlusion. By 24 h, these values had returned to control levels. The increase in VO2 was inhibited by injection of the beta-adrenergic antagonist propranolol but was unaffected by injection of the cyclooxygenase inhibitor ibuprofen. The thermogenic activity of brown adipose tissue was assessed from in vitro binding of guanosine diphosphate to mitochondria isolated from intact and surgically denervated lobes of sham-operated and ischemic rats, 6 h after surgery. Brown adipose tissue specific guanosine diphosphate (GDP) binding was elevated by 86% in intact tissue from ischemic compared with sham-operated rats but was identical in denervated tissue from the two groups. Brown adipose tissue activity correlated with resting oxygen consumption in the ischemic group (r = 0.85, p less than 0.01) but not in controls (r = -0.35, NS). Thus occlusion of the middle cerebral artery in the rat may provide a representative model for both stroke and head injury in man. It is associated with a transient increase in metabolic rate and by sympathetically mediated activation of brown adipose tissue in the rat.