Neuroprotective effects of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), an antioxidant in middle cerebral artery occlusion induced focal cerebral ischemia in rats

OBJECTIVES: In the present study, we have investigated the neuroprotective potential of 6hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), in middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia. METHODS: Sprague-Dawley rats were subjected to 2 hours of MCAO followed by 22 or 70 hours of reperfusion. After reperfusion, rats were evaluated for neurological deficits and cerebral infarction. Brain malondialdehyde (MDA) level and in situ terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL) were also estimated. RESULTS: Focal cerebral ischemia produced a significant infarct volume and neurological scores as compared with sham-operated animals. Cerebral ischemia reperfusion injury was associated with an increase in lipid peroxidation in ipsilateral and contralateral hemisphere of brain along with an increase in TUNEL positive cells in ipsilateral hemisphere of brain sections indicating oxidative stress and DNA fragmentation, respectively. Trolox (10 and 30 mg/kg, i.p.) treatment significantly decreased neurological damage which was evident from the reduction in infarct volume and neurological score. Trolox (30 mg/kg) also attenuated oxidative stress and DNA fragmentation. DISCUSSION: Oxidative stress-induced neuronal damage is implicated in the pathophysiology of cerebral ischemia. Our study suggests that Trolox is a potent neuroprotective agent in focal cerebral ischemia and its neuroprotective effects may be attributed to the reduction of lipid peroxidation and DNA fragmentation.     

Neuroprotective effects of rutaecarpine on cerebral ischemia reperfusion injury**

Rutaecarpine,an active component of the traditional Chinese medicine Tetradium ruticarpum,has been shown to improve myocardial ischemia reperfusion injury.Because both cardiovascular and cerebrovascular diseases are forms of ischemic vascular disease,they are closely related.We hypothesized that rutaecarpine also has neuroprotective effects on cerebral ischemia reperfusion injury.A cerebral ischemia reperfusion model was established after 84,252 and 504 μg/kg rutaecarpine were given to mice via intraperitoneal injection,daily for 7 days.Results of the step through test,2,3,5-triphenyl tetrazolium chloride dyeing and oxidative stress indicators showed that rutaecarpine could improve learning and memory ability,neurological symptoms and reduce infarction volume and cerebral water content in mice with cerebral ischemia reperfusion injury.Rutaecarpine could significantly decrease the malondialdehyde content and increase the activities of superoxide dismutase and glutathione peroxidase in mouse brain.Therefore,rutaecarpine could improve neurological function following injury induced by cerebral ischemia reperfusion,and the mechanism of this improvement may be associated with oxidative stress.These results verify that rutaecarpine has neuroprotective effects on cerebral ischemia reperfusion in mice.     

Hispidulin Protects Against Focal Cerebral Ischemia Reperfusion Injury in Rats

Focal cerebral ischemia is associated with ischemia/reperfusion (I/R) injury. Hispidulin is a flavonoid compound with a variety of pharmacological properties. The neuroprotective effects of hispidulin have not been fully elucidated. Herein, we demonstrated that pretreatment of animals with hispidulin improved the neurological outcomes and decreased the infarct size and brain edema in the cerebral focal I/R model. Mechanistically, we showed in vivo and in vitro that hispidulin exerted a protective effect against I/R injury by inducing the Nrf2 antioxidant pathway through modulation of AMPK/GSK3β signaling. Taken together, our results suggest that hispidulin may be a useful neuroprotective agent against ischemia/reperfusion (I/R) injury.     

Neuroprotective mechanisms of curcumin against cerebral ischemia-induced neuronal apoptosis and behavioral deficits

Increased oxidative stress has been regarded as an important underlying cause for neuronal damage induced by cerebral ischemia/reperfusion (I/R) injury. In recent years, there has been increasing interest in investigating polyphenols from botanical source for possible neuroprotective effects against neurodegenerative diseases. In this study, we investigated the mechanisms underlying the neuroprotective effects of curcumin, a potent polyphenol antioxidant enriched in tumeric. Global cerebral ischemia was induced in Mongolian gerbils by transient occlusion of the common carotid arteries. Histochemical analysis indicated extensive neuronal death together with increased reactive astrocytes and microglial cells in the hippocampal CA1 area at 4 days after I/R. These ischemic changes were preceded by a rapid increase in lipid peroxidation and followed by decrease in mitochondrial membrane potential, increased cytochrome c release, and subsequently caspase-3 activation and apoptosis. Administration of curcumin by i.p. injections (30 mg/kg body wt) or by supplementation to the AIN76 diet (2.0 g/kg diet) for 2 months significantly attenuated ischemia-induced neuronal death as well as glial activation. Curcumin administration also decreased lipid peroxidation, mitochondrial dysfunction, and the apoptotic indices. The biochemical changes resulting from curcumin also correlated well with its ability to ameliorate the changes in locomotor activity induced by I/R. Bioavailability study indicated a rapid increase in curcumin in plasma and brain within 1 hr after treatment. Together, these findings attribute the neuroprotective effect of curcumin against I/R-induced neuronal damage to its antioxidant capacity in reducing oxidative stress and the signaling cascade leading to apoptotic cell death.     

Anemonin Alleviates Nerve Injury After Cerebral Ischemia and Reperfusion (I/R) in Rats by Improving Antioxidant Activities and Inhibiting Apoptosis Pathway

In the present study, we aimed at evaluating the potential neuroprotective effect and the underlying mechanism of anemonin against cerebral ischemia and reperfusion (I/R) injury. Anemonin was administered to rats by the intraperitoneally (i.p.) route once daily for 7 days before middle cerebral artery occlusion (MCAO). Focal cerebral ischemia was induced by 90 min of MCAO followed by 24 h of reperfusion. After that, animals were sacrificed by decapitation, brain was removed, and various biochemical estimations, neurological status, and assessment of cerebral infarct size were carried out. MCAO followed by 24 h of reperfusion caused a significant increase in infarct size, neurological deficit score, malondialdehyde (MDA) content, reactive oxygen species (ROS) level, and DNA fragmentation, as well as a decrease in the activities of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GPx), and Na⁺, K⁺-ATPase in the brain. Furthermore, elevated Bax expression, increased caspase-3 cleavage, and decreased Bcl-2 expression were observed in nontreated rats in response to focal cerebral I/R injury. However, pretreatment with anemonin significantly reversed these levels of biochemical parameters, reduced cerebral infarct size, and improved the neurologic score in cerebral ischemic animals. Additionally, a wide distribution of anemonin in plasma and brain tissues and the brain-to-plasma partition coefficient (Ri) ratio of 0.7 at 90 min indicated that this compound could penetrate the blood-brain barrier (BBB). These results showed that pretreatment with anemonin provided a significant protection against cerebral I/R injury in rats by, at least in part, its antioxidant action and consequent inhibition of apoptosis.     

Remote limb ischemic postconditioning protects mouse brain against cerebral ischemia/reperfusion injury via upregulating expression of Nrf2, HO-1 and NQO-1 in mice

Remote ischemic postconditioning (RIPostC) is a promising therapeutic intervention, which has been discovered to reduce ischemia/reperfusion (I/R) injury in heart, kidney, brain and skeletal muscle experimentally. However, its potential protective mechanisms have not been well elucidated. The aim of this study was to investigate the protective effect of RIPostC in cerebral I/R injury and explore the new putative mechanisms of neuroprotection elicited by it. Focal cerebral ischemia was induced by transient middle cerebral artery occlusion (tMCAO) in male CD1 mice. RIPostC was generated by three cycles of 5-min reperfusion/5-min occlusion of the bilateral femoral artery on the bilateral limbs at the onset of middle cerebral artery reperfusion. RIPostC significantly improved neurological outcome, lessened infarct volume and brain edema, upregulated the expression of Nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and quinone oxidoreductase-1 (NQO-1) and activity of superoxide dismutase (SOD), and downregulaed the formation of malondialdehyde (MDA) (p < 0.05). Taken together, these findings demonstrated that RIPostC protected the brain from I/R injury after focal cerebral ischemia by reducing oxidative stress and activating the Nrf2–ARE (antioxidant response element) pathway.     

Heat shock protein 72 inhibits c-Jun N-terminal kinase 3 signaling pathway via Akt1 during cerebral ischemia

Although recent researches show that Heat Shock Protein 72 (HSP72) plays an important role in neuronal survival, little knowledge is known about the precise mechanisms during cerebral ischemia/reperfusion (I/R). Our present study investigated the neuroprotective mechanisms of HSP72 against ischemic brain injury induced by cerebral I/R. Mild heat shock pretreatment was employed to induce the overexpression of HSP72 by immersing rats into the water bath at 42°C for 20 min before cerebral I/R. HSP72 antisense oligodeoxynucleotides (ODNs) were used to inhibit HSP72 expression by intracerebroventricular infusion once per day for 3 days before cerebral I/R animal model was induced by four-vessel occlusion for 15 min transient ischemia and then reperfused for various time in Sprague-Dawley rats. Immunoprecipitation and immunoblotting were used to detect the expression of the related proteins. HE-staining and TUNEL-staining were carried out to examine the neuronal death of hippocampal CA1 region. Results showed that mild heat shock could increase the phosphorylation of protein kinase B (Akt), inhibit the assembly of MLK3-MKK7-JNK3 signaling module, diminish the phosphorylation of JNK3 and c-Jun, and decrease the activation of caspase-3. Furthermore, mild heat shock could significantly protect neurons against cerebral I/R. Whereas, all of the aforementioned effects of mild heat shock were reversed by HSP72 antisense ODNs. In summary, our results imply that Akt1 activation is involved in the neuroprotection of HSP72 against ischemic brain injury via suppressing JNK3 signaling pathway and provide a new experimental foundation for stroke therapy.     

Neuroprotective effects of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), an antioxidant in middle cerebral artery occlusion induced focal cerebral ischemia in rats

Abstract

Objectives: In the present study, we have investigated the neuroprotective potential of 6hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), in middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia.

Methods: Sprague–Dawley rats were subjected to 2 hours of MCAO followed by 22 or 70 hours of reperfusion. After reperfusion, rats were evaluated for neurological deficits and cerebral infarction. Brain malondialdehyde (MDA) level and in situ terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL) were also estimated.

Results: Focal cerebral ischemia produced a significant infarct volume and neurological scores as compared with sham-operated animals. Cerebral ischemia reperfusion injury was associated with an increase in lipid peroxidation in ipsilateral and contralateral hemisphere of brain along with an increase in TUNEL positive cells in ipsilateral hemisphere of brain sections indicating oxidative stress and DNA fragmentation, respectively. Trolox (10 and 30 mg/kg, i.p.) treatment significantly decreased neurological damage which was evident from the reduction in infarct volume and neurological score. Trolox (30 mg/kg) also attenuated oxidative stress and DNA fragmentation.

Discussion: Oxidative stress-induced neuronal damage is implicated in the pathophysiology of cerebral ischemia. Our study suggests that Trolox is a potent neuroprotective agent in focal cerebral ischemia and its neuroprotective effects may be attributed to the reduction of lipid peroxidation and DNA fragmentation.     

Tissue kallikrein alleviates glutamate‐induced neurotoxicity by activating ERK1

Glutamate‐induced neurotoxicity consequent to N‐methyl‐D‐aspartic acid (NMDA) and 2‐amino‐3‐(3‐hydroxy‐5‐methyl‐isoxazol‐4‐yl) propionic acid (AMPA) receptor activation underlies the pathogenesis of a wide range of central nervous system disorders, including brain ischemia. Prevention of ischemia/reperfusion (I/R)‐induced neuronal injury has long been regarded as an effective therapeutic strategy for ischemia. Human tissue kallikrein (TK) gene transfer has been shown to protect neurons against cerebral I/R‐induced apoptosis and oxidative stress, via activation of the brandykinin B2 receptor (B2R). However, little is known about the role of TK on glutamate‐induced neurotoxicity. Here we report that pretreatment of cultured cortical neurons with TK largely prevented glutamate‐induced morphological changes and cell death. We found that TK pretreatment alleviated glutamate‐induced oxidative stress by inhibiting neuronal nitric oxide synthase (nNOS) activity, thereby reducing the generation of nitric oxide (NO) and reactive oxygen species (ROS). Blockage of NMDA and AMPA receptors by their specific antagonists MK801 and CNQX had effects similar to those of TK administration. Furthermore, we found that the extracellular signal‐regulated kinase 1/2 cascade (ERK1/2), particularly ERK1, and nuclear factor‐κB (NF‐κB) were involved in TK neuroprotection against glutamate‐induced neurotoxicity. TK pretreatment activated ERK1 and NF‐κB, leading to enhanced expression of brain‐derived neurotrophic factor (BDNF) mRNA and antiapoptotic gene Bcl‐2 protein. Collectively, these findings demonstrate that TK attenuates glutamate‐induced apoptosis through an intracellular signaling pathway including activation of B2R, ERK1/2, and NF‐κB and up‐regulation of BDNF and Bcl‐2 expression. Thus, TK represents a promising therapeutic strategy for ischemic stroke. © 2009 Wiley‐Liss, Inc.     

Detrimental effects of post-treatment with fatty acids on brain injury in ischemic rats

Studies have illustrated that fatty acids, especially polyunsaturated fatty acids (PUFA), have a role in regulating oxidative stress via the enhancement of antioxidative defense capacity or the augmentation of oxidative burden. Elevated oxidative stress has been implicated in the pathogenesis of brain injury associated with cerebral ischemia/reperfusion (I/R). The objective of this study was to assess whether treatment with fatty acids after focal cerebral I/R induced by occlusion of the common carotid arteries and the middle cerebral artery has effects on brain injury in a rat model. PUFA, including arachidonic acid (AA) and docosahexaenoic acid (DHA), and the saturated fatty acid, stearic acid (SA), were administrated 60 min after reperfusion via intraperitoneal injection. AA and DHA aggravated cerebral ischemic injury, which manifested as enlargement of areas of cerebral infarction and increased impairment of motor activity, in a concentration-dependent manner. However, there were no remarkable differences in post-ischemic alterations between the SA and saline groups. The post-ischemic augmentation of injury in AA and DHA treatment groups was accompanied by increases in the permeability of the blood-brain barrier (BBB), brain edema, metalloproteinase (MMP) activity, inflammatory cell infiltration, cyclooxygenase 2 (COX-2) expression, caspase 3 activity, and malondialdehyde (MDA) production, and by a decrease in the brain glutathione (GSH) content. Furthermore, we found that either AA or DHA alone had little effect on free radical generation in neuroglia, but they greatly increased the hydrogen peroxide-induced oxidative burden. Taken together, these findings demonstrate the detrimental effect of PUFA such as AA and DHA in post-ischemic progression and brain injury after cerebral I/R is associated with augmentation of cerebral I/R-induced alterations, including oxidative changes.     

异丙酚预处理大鼠缺血再灌注脑皮质细胞的凋亡

The present study aimed to observe cortical expression of Bcl-2 and Bax,cysteine-dependent aspartate directed proteases-3 activity and apoptotic cell death in a rat model of middle cerebral artery occlusion pretreated with propofol.Results showed that,propofol pretreatment significantly reduced oxidative stress levels and attenuated neuronal apoptosis in the cortex of rats.Propofol pretreatment upregulated Bcl-2 expression,and downregulated Bax expression and cysteine-dependent aspartate directed proteases-3 activity.These findings indicate that propofol pretreatment inhibits cell apoptosis during focal cerebral ischemia/reperfusion injury.This neuroprotective effect is most likely achieved through the Bcl-2/Bax/cysteine-dependent aspartate directed proteases-3 pathway.     

Pre- and post-treatments with escitalopram protect against experimental ischemic neuronal damage via regulation of BDNF expression and oxidative stress

Selective serotonin re-uptake inhibitors (SSRI) have been widely used in treatment of major depression because of their efficacy, safety, and tolerability. Escitalopram, an SSRI, is known to decrease oxidative stress in chronic stress animal models. In the present study, we examined the neuroprotective effects of pre- and post-treatments with 20 mg/kg and 30 mg/kg escitalopram in the gerbil hippocampal CA1 region (CA1) after transient cerebral ischemia. Pre-treatment with escitalopram protected against ischemia-induced neuronal death in the CA1 after ischemia/reperfusion (I/R). Post-treatment with 30 mg/kg, not 20 mg/kg, escitalopram had a neuroprotective effect against ischemic damage. In addition, 20 mg/kg pre- and 30 mg/kg post-treatments with escitalopram increased brain-derived neurotrophic factor (BDNF) protein levels in the ischemic CA1 compared to vehicle-treated ischemia animals. In addition, 20 mg/kg pre- and 30 mg/kg post-treatments with escitalopram reduced microglia activation and decreased 4-hydroxy-2-nonenal and Cu,Zn-superoxide dismutase immunoreactivity and their levels in the ischemic CA1 compared to vehicle-treated ischemia animals after transient cerebral ischemia. In conclusion, these results indicated that pre- and post-treatments with escitalopram can protect against ischemia-induced neuronal death in the CA1 induced by transient cerebral ischemic damage by increase of BDNF as well as decrease of microglia activation and oxidative stress.     

茶氨酸对脑缺血再灌注损伤保护作用的实验研究

目的观察茶氨酸对脑缺血再灌注损伤的保护作用,为临床脑缺血再灌注损伤的预防和治疗提供实验依据。方法将24只健康家兔随机分为四组：假手术组、脑缺血组、茶氨酸予处理组和茶氨酸治疗组。麻醉后分离血管,采用基底动脉、双侧颈总动脉结扎法制备急性全脑缺血再灌注动物模型。假手术组仅分离动脉不结扎,予处理组在缺血前应用茶氨酸,治疗组在缺血后应用茶氨酸,缺血组不作特殊药物处理。各组分别在规定时间点即缺血前、再灌注后30min、1h、2h采血测定神经特异性烯醇化酶(NSE)含量,取脑组织活检观察超微结构,处死动物测定脑含水量。结果茶氨酸予处理组和治疗组以上各项指标均较脑缺血组有显著的改善,提示茶氨酸具有神经保护作用。实验还显示茶氨酸予处理组在再灌注30min时NSE含量与假手术组比较无差异,提示用茶氨酸予处理后可能使缺血后脑损害的发生延迟,为进一步的治疗争取了宝贵时间。结论茶氨酸对脑缺血再灌注损伤有保护作用,值得进一步研究。     

Gemfibrozil Pretreatment Affecting Antioxidant Defense System and Inflammatory, but not Nrf-2 Signaling Pathways Resulted in Female Neuroprotection and Male Neurotoxicity in the Rat Models of Global Cerebral Ischemia–Reperfusion

Two important pathophysiological mechanisms involved during cerebral ischemia are oxidative stress and inflammation. In pathological conditions such as brain ischemia the ability of free radicals production is greater than that of elimination by endogenous antioxidative systems, so brain is highly injured due to oxidation and neuroinflammation. Fibrates as peroxisome proliferator-activated receptor (PPAR)-α ligands, are reported to have antioxidant and anti-inflammatory actions. In this study, gemfibrozil, a fibrate is investigated for its therapeutic potential against global cerebral ischemia–reperfusion (I/R) injury of male and female rats. This study particularly has focused on inflammatory and antioxidant signaling pathways, such as nuclear factor erythroid-related factor (Nrf)-2, as well as the activity of some endogenous antioxidant agents. It was found that pretreatment of animals with gemfibrozil prior to I/R resulted in a sexually dimorphic outcome. Within females it proved to be protective, modulating inflammatory factors and inducing antioxidant defense system including superoxide dismutase (SOD), catalase, as well as glutathione level. However, Nrf-2 signaling pathway was not affected. It also decreased malondialdehyde level as an index of lipid peroxidation. In contrast, gemfibrozil pretreatment was toxic to males, enhancing the expression of inflammatory factors such as tumor necrosis factor-α, nuclear factor-κB, and cyclooxygenase-2, and decreasing Nrf-2 expression and SOD activity, leading to hippocampal neurodegeneration. Considering that gemfibrozil is a commonly used anti-hyperlipidemic agent in clinic, undoubtedly more investigations are crucial to exactly unravel its sex-dependent neuroprotective/neurodegenerative potential.     

一种C-Jun N-末端激酶肽抑制剂在沙土鼠全脑缺血中的保护作用

目的 为了进一步研究海马C1区域神经细胞活动中JNK的作用，我们评价了一种JNK抑制剂即D-JNKI1在沙土鼠一过性大脑缺血模型中对迟发性神经细胞死亡（DND）的作用。方法 55只沙土鼠随机分为11个组。5组沙土鼠先接受5min前脑缺血处理，再灌注3h后，通过立体定向方法。向每组沙土鼠右侧侧脑室内分别注入不同浓度的D-JNKI1（2μL PBS内加入0．00012，0．0012，0．012，0．12，1．2μmol／L D-JNKI1，每组n=5）。对照组（n=5）：沙土鼠先接受5min前脑缺血处理，再灌注3h后，通过立体定向方法方法向右侧侧脑室内仅注入PBS2μL。腹腔内注射组（n=5）沙土鼠；先接受5min前脑缺血处理，再灌注3h后，1．2μmol／L D-JNKI1溶于0．5mL PBS腹腔内注射。假手术组（n=5）；沙土鼠仅暴露双侧颈总动脉，未夹闭。预处理组（共3组，n=15）：先将0．0012μmol／L D-JNKI1，0．00012μmol／L D-JNKI1溶于2μL PBS，分别注入两组沙土鼠的右侧侧脑室内，另外一组沙土鼠的右侧侧脑室内仅仅注入PBS2μL，30min后三组均夹闭双侧颈总动脉2min，48h后再次接受双侧颈总动脉夹闭5min。所有沙土鼠从接受夹闭5min双侧颈总动脉后4d处死，作冰冻切片和Niss1染色。结果 缺血再灌注3h后用D-JNKI-1治疗，有神经保护作用，最好的神经保护效应浓度为0．0012μmol／L。D-JNKI-1预处理加强了2min预处理所诱导的缺血耐受效应。结论D-JNKI1在沙土鼠全脑缺血模型中对海马CA1区域的迟发性神经细胞死亡有潜在的神经保护作用。     

局灶性脑缺血再灌注大鼠过氧化物酶体增殖物激活受体γ核移位的改变

目的 观察过氧化物酶体增殖物激活受体γ(PPARγ)在脑缺血再灌注损伤中核移位的改变,并初步探讨该改变在脑缺血损伤中的意义.方法 健康雄性SD大鼠制作大脑中动脉阻塞再灌注模型,缺血60 min,再灌注4、8、24 h.采用Western blot法、免疫组织化学和免疫荧光染色法观察PPARγ核移位的改变以及PPARγ激动剂和拮抗剂对PPARγ核移位的影响;同时,2,3,5-氯化三苯四唑(TTC)染色法观察脑梗死体积的改变.结果 (1)Western blot检测显示,脑缺血再灌注4 h即引起PPARγ核蛋白增加,同时胞质蛋白减少,差异具有统计学意义.随再灌注时间的增加,PPARγ核移位呈时间依赖性增强.免疫组织化学和免疫荧光染色均显示,与假手术组48.3%相比,缺血再灌注24 h胞核PPARγ阳性增加到80.3%,差异具有统计学意义(t=8.63,P=0.00).(2)与单纯缺血再灌注组相比,PPARγ激动剂进一步增加PPARγ核蛋白表达,同时减少胞质蛋白表达,差异均具有统计学意义;相反,PPARγ抑制剂GW9662则降低核蛋白水平而增加胞质表达,差异均具有统计学意义.(3)经TTC染色显示,与单纯缺血再灌注组相比,PPARγ激动剂使脑梗死体积减少了48.40%(15.46±4.94与29.96 ±3.39,t=5.93,P=0.00);而PPARγ抑制剂则使脑梗死体积增加了58.95%(47.62±4.93与29.96±3.39,t=7.23,P=0.00).结论 脑缺血再灌注损伤使大鼠PPARγ核移位增加,该改变可能是脑组织的一种自我保护性反应.     

Delayed treatment with nicotinamide (Vitamin B(3)) improves neurological outcome and reduces infarct volume after transient focal cerebral ischemia in Wistar rats

BACKGROUND AND PURPOSE: We have previously shown that nicotinamide (NAm) acutely reduces brain infarction induced by permanent middle cerebral artery occlusion (MCAo) in rats. In this study, we investigate whether NAm may protect against ischemia/reperfusion injury by improving sensory and motor behavior as well as brain infarction volumes in a model of transient focal cerebral ischemia. METHODS: Forty-eight male Wistar rats were used, and transient focal cerebral ischemia was induced by MCAo for 2 hours, followed by reperfusion for either 3 or 7 days. Animals were treated with either intraperitoneal saline or NAm (500 mg/kg) 2 hours after the onset of MCAo (ie, on reperfusion). Sensory and motor behavior scores and body weight were obtained daily, and brain infarction volumes were measured on euthanasia. RESULTS: Relative to treatment with saline, treatment with NAm (500 mg/kg IP) 2 hours after the onset of transient focal cerebral ischemia in Wistar rats significantly improved sensory (38%, P<0.005) and motor (42%, P<0.05) neurological behavior and weight gain (7%, P<0.05) up to 7 days after MCAo. The cerebral infarct volumes were also reduced 46% (P<0.05) at 3 days and 35% (P=0.09) at 7 days after MCAo. CONCLUSIONS: NAm is a robust neuroprotective agent against ischemia/reperfusion-induced brain injury in rats, even when administered up to 2 hours after the onset of stroke. Delayed NAm treatment improved both anatomic and functional indices of brain damage. Further studies are needed to clarify whether multiple doses of NAm will improve the extent and duration of this neuroprotective effect and to determine the mechanism(s) of action underlying the neuroprotection observed. Because NAm is already used clinically in large doses and has few side effects, these results are encouraging for the further examination of the possible use of NAm as a therapeutic neuroprotective agent in the clinical treatment of acute ischemic stroke.     

Scorpion Venom Heat-Resistant Peptide is Neuroprotective against Cerebral Ischemia-Reperfusion Injury in Association with the NMDA-MAPK Pathway

Scorpion venom heat-resistant peptide(SVHRP)is a component purified from Buthus martensii Karsch scorpion venom. Our previous studies have shown that SVHRP is neuroprotective in models of Alzheimer's disease and Parkinson's disease. The present study aimed to explore the potential neuroprotective effects of SVHRP on cerebral ischemia/reperfusion(I/R) injury, using a mouse model of middle cerebral artery occlusion/reperfusion(MCAO/R) and a cellular model of oxygen-glucose deprivation/reoxygenation(OGD/R). Our results showed that SVHRP treatment decreased the neurological deficit scores, edema formation, infarct volume and neuronal loss in the MCAO/R mice, and protected primary neurons against OGD/R insult. SVHRP pretreatment suppressed the alterations in protein levels of N-methyl-D-aspartate receptors(NMDARs) and phosphorylated p38 MAPK as well as some proinflammatory factors in both the animal and cellular models. These results suggest that SVHRP has neuroprotective effects against cerebral I/R injury, which might be associated with inhibition of the NMDA-MAPKmediated excitotoxicity.     

Picroside II Exerts a Neuroprotective Effect by Inhibiting the Mitochondria Cytochrome C Signal Pathway Following Ischemia Reperfusion Injury in Rats

Stroke is a common neurodegenerative disease in the wide world, and mitochondrial defects underlie the pathogenesis of ischemia, especially during reperfusion. Picroside II, the principal active component of Picrorhiza, is a traditional Chinese medicine. Our previous study demonstrated that the best therapeutic dose and time window were injection of picroside II at a dose of 10–20 mg/kg body weight following cerebral ischemia by 1.5–2.0 h. In this paper, the neuroprotective effect and the mechanism of picroside II were investigated, as well as its involvement in antioxidant and mitochondria cytochrome C (CytC) signal pathway following ischemia reperfusion (I/R) injury in rats. After 24 h of cerebral I/R, the neurobehavioral function was measured by modified neurological severity score test; the content of reactive oxygen species in brain tissue was measured by enzyme-linked immunosorbent assay; the cerebral infarction volume was detected by TTC staining; the morphology of brain tissue was observed by hematoxylin-eosin; the apoptotic cells were counted by terminal deoxynucleotidyl transferase dUTP nick end labeling assay; the ultrastructure of the cortical brain tissues was observation by transmission electron microscopy; the expressions of CytC and Caspase-3 were determined by immunohistochemical assay and Western blot. The results indicated that picroside II could scavenge ROS contents, decrease the cerebral infarction volume and apoptotic cells, protect the structure of mitochondria, down-regulate the expression of CytC and Caspase-3 in cerebral I/R rats. It can be concluded that picroside II exerts a neuroprotective effect by inhibiting the mitochondria CytC signal pathway following ischemia reperfusion injury in rats.