右美托咪啶通过抑制p38和JNK活化减少异氟醚诱导的新生大鼠海马神经元凋亡

 目的：探讨右美托咪啶（dexmedetomidine, Dex）对异氟醚（isoflurane, Iso）诱导的新生大鼠海马神经元凋亡的影响及其与p38丝裂原活化蛋白激酶（p38 mitogen-activated protein kinase,p38）和c-Jun 氨基末端激酶（c-Jun N-terminal kinase, JNK）蛋白活化的关系。方法：48只出生后7 d的SD大鼠随机分为对照组（Con组）、Dex组、Iso组和Iso+Dex组。前2组吸入空气,后2组吸入0.75% Iso 6 h。Dex组和Iso+Dex组在麻醉前20 min和麻醉开始后2 h、4 h经腹腔注射25 μg·kg-1 Dex;Con组和Iso组则在相同的时点注射150 μL生理盐水。麻醉结束后使用TUNEL法检测海马神经元凋亡; Western blotting检测海马组织激活型caspase-3、p38、磷酸化p38（p-p38）、JNK和磷酸化JNK（p-JNK）蛋白表达的变化。结果：(1) Iso组海马CA1区TUNEL阳性细胞数较Con组增加447.57%（P<0.01）,Dex抑制Iso诱导的TUNEL阳性细胞增加达75.18%（P<0.01）。(2) Iso组海马组织激活型caspase-3的表达比Con组增加126.29% （P<0.01）;Dex显著抑制了Iso诱导的caspase-3活化（P<0.01）。(3) Iso组海马p-p38/p38和p-JNK/JNK比值均较Con组明显增加（P<0.01）;Dex显著抑制了Iso诱导的p-p38 和p-JNK表达增加（P<0.01）。结论：Dex能通过减少海马神经元凋亡来减轻Iso对新生大鼠的脑毒性。抑制p38和JNK的磷酸化可能是Dex发挥保护作用的机制之一。     

A high soy diet reduces programmed cell death and enhances bcl-xL expression in experimental stroke

Soy phytoestrogens have been proposed as an alternative to estrogen replacement therapy and have demonstrated potential neuroprotective effects in the brain. We have shown that a high soy diet significantly reduces infarct size following permanent middle cerebral artery occlusion (MCAO). Here, we tested the hypothesis that a high soy diet would attenuate programmed cell death after stroke. Adult female Sprague-Dawley rats were ovariectomized and fed either an isoflavone-reduced diet (IFP) or a high soy diet (SP) for 2 weeks before undergoing 90 min of transient middle cerebral artery occlusion (tMCAO) followed by 22.5 h reperfusion. Infarct size, as assessed by triphenyltetrazolium chloride staining, was significantly reduced by a high soy diet (P<0.05). Apoptosis in the ischemic cortex, measured by TUNEL staining, was significantly reduced by the high soy diet. The number of active caspase-3 positive cells and caspase-mediated alpha-spectrin cleavage were also significantly decreased in the ischemic cortex of SP rats. Furthermore, nuclear translocation of apoptosis-inducing factor (AIF) was significantly reduced in the ischemic cortex of SP rats. Soy significantly increased bcl-x(L) mRNA and protein expression in the ischemic cortex compared with IFP rats. Immunohistochemistry revealed increased neuronal expression of bcl-2 and bcl-x(L) in the ischemic cortex of both IFP and SP rats following tMCAO. These results suggest that a high soy diet decreases both caspase-dependent and caspase-independent programmed cell death following tMCAO. Further, a high soy diet enhances expression of the cell survival factor bcl-x(L) following tMCAO, contributing to the neuroprotective effects of soy in the ischemic cortex.     

慢病毒载体介导HIF-1α基因修饰骨髓间质干细胞促进脑缺血大鼠的神经功能恢复

目的： 探讨静脉注射低氧诱导因子（HIF-1α）修饰的骨髓间质干细胞对脑缺血大鼠神经功能恢复的影响及其可能的作用机制。方法: 利用慢病毒载体介导HIF-1α基因修饰骨髓间质干细胞,获得稳定转染HIF-1α的骨髓间质干细胞,于缺血后3 h经股静脉进行体内移植。在细胞移植后的1、7、14、28 d进行神经功能检查,使用TTC染色观察缺血体积,分别通过TUNEL和pax6、DCX抗体免疫荧光双标分析缺血侧脑组织的神经细胞凋亡及内源性神经干细胞增殖、存活情况。结果: 脑缺血BMSCs-mHIF-1α治疗组在14 d和28 d大鼠神经功能评分显著低于缺血组 (P<0.05),神经功能得到明显改善;脑缺血BMSCs-mHIF-1α治疗组脑梗死灶体积小于缺血组;脑缺血BMSCs-mHIF-1α治疗组缺血侧脑组织的神经细胞凋亡在14 d和28 d明显少于缺血组 (P<0.05);细胞移植后7 d,脑缺血BMSCs-mHIF-1α治疗组在海马区域观察到pax6/DCX细胞数量明显多于缺血组（P<0.05）。结论: 静脉注射HIF-1α修饰骨髓间质干细胞能够促进脑缺血大鼠神经功能恢复;抗凋亡及激活并促进内源性神经干细胞迁移至缺血区可能是静脉注射HIF-1α修饰骨髓间质干细胞治疗脑缺血的机制。     

川芎嗪联合骨髓间充质干细胞移植抑制脑缺血大鼠神经细胞凋亡

目的:研究川芎嗪(tetramethylpyrazine,TMP)联合骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)对脑缺血大鼠神经细胞凋亡及Bcl-2、Bax表达的影响。方法:采用全骨髓贴壁法体外培养BMSCs,传代至第3代用于尾静脉移植。采用线栓法诱导大鼠右侧大脑中动脉阻塞模型,除假手术组外,大鼠随机分为模型组、BMSCs(1×10~9/L)组、川芎嗪(40 mg/kg)组和联合(川芎嗪+BMSCs)组,每组12只。缺血后第1、7和14天采用改良的神经损伤严重程度评分(modified neurological severity scoring,m NSS)进行神经功能评价。缺血后第14天,甲苯胺蓝染色检测脑梗死体积,HE染色观察脑组织病理学变化,采用原位末端标记(TUNEL)法观察神经细胞凋亡数,采用实时荧光定量PCR法和Western blot法检测Bax和Bcl-2的mRNA及蛋白表达。结果:与BMSCs组和川芎嗪组比较,联合组m NSS评分显著减少(P0.01),梗死体积显著减少(P0.01),缺血引起的脑缺血周边区病理性损伤明显减轻,TUNEL阳性细胞数显著减少(P0.01),Bcl-2的mRNA及蛋白表达显著增加,Bax的mRNA及蛋白表达显著降低(P0.01)。结论:川芎嗪联合BMSCs移植能显著促进脑缺血后大鼠的功能恢复,减少梗死体积,减轻脑组织缺血性损伤,抑制神经细胞凋亡,机制可能与调控Bcl-2和Bax的表达有关。     

黄芪注射液对脑缺血再灌注大鼠海马神经元凋亡及JNK3表达的影响

目的:观察黄芪注射液对脑缺血再灌注大鼠海马神经元凋亡及c-Jun N末端激酶3(JNK3)表达的影响。方法:四血管阻断法制备脑缺血再灌注大鼠模型。设假手术组、脑缺血再灌注模型组(模型组)、脑缺血再灌注模型+黄芪注射液组(黄芪注射液组)和脑缺血再灌注模型+黄芪注射液溶剂对照组(溶剂对照组)。除假手术组外其余3组根据再灌注时间不同又分为0 h、0.5 h、2 h、6 h、24 h、72 h和120 h 7个亚组。采用TUNEL法检测海马神经元凋亡,Western blotting法检测海马组织JNK3蛋白变化,real-time PCR法检测海马组织JNK3 mRNA 的表达变化。结果:与假手术组比,模型组大鼠各个时点凋亡细胞数均增多(P<0.05);与模型组比,黄芪注射液组各个时点的细胞凋亡数明显减少(P<0.05),而黄芪注射液溶剂对照组各个时点的细胞凋亡数无明显变化(P>0.05)。除120 h外,模型组各时点海马组织JNK3蛋白及mRNA表达均较假手术组增加(P<0.05);与模型组相比,黄芪注射液可减弱除120 h之外的各时点JNK3 蛋白及mRNA的表达(P<0.05),而黄芪注射液溶剂对照组则无明显变化(P>0.05)。结论:黄芪注射液可抑制脑缺血再灌注大鼠海马神经元凋亡,其抗凋亡机制可能与下调JNK3 mRNA及蛋白表达有关。     

Treg细胞及TGFβ-1免疫调节功能紊乱加重小鼠缺血性脑损伤

目的:通过检测小鼠短暂性脑缺血(tMCAO)后不同时间点CD4+CD25+调节性T细胞(Treg)比例及血清TGF-β1浓度变化,探讨其免疫调节功能在缺血性脑卒中炎性损伤中作用。方法:60只昆明小鼠随机分为6组,假手术组(sham组,24 h)10只,缺血再灌注后12 h、24 h、48 h、72 h及5 d五个tMCAO组(n=10/组)。采用腔内线栓法建立小鼠tM-CAO模型;tMCAO组在再灌注后各时间点进行神经功能缺陷评分(NDS),其后处死小鼠行氯化三苯基四氮唑(TTC)染色观察脑梗死容积变化;同期免疫荧光染色观察脾脏中Foxp3表达;提取脾脏单个核细胞,流式细胞术(FCM)测定Treg在单个核细胞中比例;分离血清,ELISA检测血清中TGF-β1浓度。结果:缺血再灌注12 h脑部炎性损伤明显,且逐渐加重,TTC染色示炎症反应中心脑梗死面积同期增大,缺血再灌注48 h达高峰,此后前述表现逐渐减小;随再灌注时间延长,神经功能也逐渐改善。Foxp3在各组小鼠脾脏中均有阳性表达,但存在明显差异;FCM分析发现,缺血再灌注24 h时Treg比例较sham组明显减少(P<0.05),但在72 h时Treg基本恢复正常,5 d时则明显高于sham组(P<0.05)。血清中TGF-β1浓度与Treg有相似表现,再灌注24 h时降低明显,48 h则恢复至sham组水平,而在5 d时高出sham组(P<0.05)。并且Treg与TGF-β1呈正相关。结论:在缺血性脑损伤急性期Treg与TGF-β1明显减少,而在恢复期二者大量增加,且与脑梗死容积变化紧密相关,说明缺血性脑损伤后Treg与TGF-β1功能失衡在急性缺血性脑卒中炎性损伤中发挥着重要作用。     

Down-regulated Na+/K+-ATPase activity in ischemic penumbra after focal cerebral ischemia/reperfusion in rats

This study was aimed to examine whether the Na⁺/K⁺ adenosine triphosphatase (Na⁺/K⁺-ATPase) activity in ischemic penumbra is associated with the pathogenesis of ischemia/reperfusion-induced brain injury. An experimental model of cerebral ischemia/reperfusion was made by transient middle cerebral artery occlusion (tMCAO) in rats and the changes of Na⁺/K⁺-ATPase activity in the ischemic penumbra was examined by Enzyme Assay Kit. Extensive infarction was observed in the frontal and parietal cortical and subcortical areas at 6 h, 24 h, 48 h, 3 d and 7 d after tMCAO. Enzyme Assay analyses revealed the activity of Na⁺/K⁺-ATPase was decreased in the ischemic penumbra of model rats after focal cerebral ischemia/reperfusion compared with sham-operated rats, and reduced to its minimum at 48 h, while the infarct volume was enlarged gradually. In addition, accompanied by increased brain water content, apoptosis-related bcl-2 and Bax proteins, apoptotic index and neurologic deficits Longa scores, but fluctuated the ratio of bcl-2/Bax. Correlation analysis showed that the infarct volume, apoptotic index, neurologic deficits Longa scores and brain water content were negatively related with Na⁺/K⁺-ATPase activity, while the ratio of bcl-2/Bax was positively related with Na⁺/K⁺-ATPase activity. Our results suggest that down-regulated Na⁺/K⁺-ATPase activity in ischemic penumbra might be involved in the pathogenesis of cerebral ischemia/reperfusion injury presumably through the imbalance ratio of bcl-2/Bax and neuronal apoptosis, and identify novel target for neuroprotective therapeutic intervention in cerebral ischemic disease.     

A novel calpain inhibitor, ((1S)-1((((1S)-1-benzyl-3-cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl) carbamic acid 5-methoxy-3-oxapentyl ester, protects neuronal cells from cerebral ischemia-induced damage in mice

Cerebral ischemia induces Ca(2+) influx into neuronal cells, and activates several proteases including calpains. Since calpains play important roles in neuronal cell death, calpain inhibitors may have potential as drugs for cerebral infarction. ((1S)-1((((1S)-1-Benzyl-3- cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl) carbamic acid 5-methoxy-3-oxapentyl ester (SNJ-1945) is a novel calpain inhibitor that has good membrane permeability and water solubility. We evaluated the effect of SNJ-1945 on the focal brain ischemia induced by middle cerebral artery occlusion (MCAO) in mice. Brain damage was evaluated by assessing neurological deficits at 24 h or 72 h after MCAO and also by examining 2,3,5-triphenyltetrazolium chloride (TTC) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining of brain sections. When injected at 1 h after MCAO, SNJ-1945 at 30 and 100 mg/kg, i.p. decreased the infarction volume and improved the neurological deficits each assessed at 24 h. SNJ-1945 at 100 mg/kg, i.p. also showed neuroprotective effects at 72 h and reduced the number of TUNEL-positive cells at 24 h. SNJ-1945 was able to prevent neuronal cell death even when it was injected at up to 6 h, but not at 8 h, after MCAO. In addition, SNJ-1945 decreased cleaved alpha-spectrin at 6 h and 12 h, and active caspase-3 at 12 h and 24 h in ischemic brain hemisphere. These findings indicate that SNJ-1945 inhibits the activation of calpain, and offers neuroprotection against the effects of acute cerebral ischemia in mice even when given up to 6 h after MCAO. SNJ-1945 may therefore be a potential drug for stroke.     

Granzyme-b is involved in mediating post-ischemic neuronal death during focal cerebral ischemia in rat model

Although peripheral immune cells infiltrate ischemic infarct tissue and elicit immune injury, the role of Cytotoxic T Lymphocytes (CTLs) and the toxins they release in mediating neuronal death is not well understood. Granzyme-b (Gra-b), a serine protease found in the cytoplasmic granules of CTLs and natural killer cells, plays an important role in inducing target cell death by activating several caspases and by initiating caspase-independent pathways that contribute to target cell death. To determine if CTLs and Gra-b are involved in post-ischemic cerebral cell death; we investigated the role of CD8⁺ CTLs and Gra-b in ischemic rat brain infarct after transient middle cerebral artery occlusion (tMCAO) and in sham-operated animals. We observed that CTLs infiltrate the ischemic infarct within 1 h of reperfusion. There was a significant increase in Gra-b levels in the ischemic region starting from 1 h until 3 day which correlated with increased levels of chemokines (IP-10/CXCL10, IL-2) and TNF-α. Co-immunoprecipitation experiments show that Gra-b interacts with Bid, PARP, and caspase-3 in ischemic samples. Immunofluorescence analysis of Gra-b and TUNEL showed that Gra-b is present both in apoptotic and necrotic cells. Triple immunostaining further confirmed that the Gra-b positive degenerating cells were neurons. CTLs in close spatial proximity to degenerating neurons, increased levels of Gra-b, localization in neurons positive for TUNEL, and interaction with other pro-apoptotic proteins indicate that Gra-b and CTLs play a significant role in neuronal death following cerebral ischemia in the rat brain after tMCAO. Based on the above findings we support our hypothesis that Gra-b secreted from activated CTLs might be involved in aggravating post-ischemic damage by mediating neuronal death.     

缺氧诱导因子-1α抑制剂对大鼠局部脑缺血再灌注损伤的影响

目的研究大鼠局部脑缺血再灌注损伤时,缺氧诱导因子-1α(HIF-1α)抑制剂2-甲氧雌二醇(2ME2)对损伤脑组织的影响。方法雄性SD大鼠60只随机分为假手术组、大脑中动脉阻塞再灌注组(MCAO组)、假性治疗组(DMSO组)、2ME2治疗组(2ME2组)。治疗组在术后1h腹腔注射相应剂量药物。观察各组大鼠神经行为学缺陷;再灌注7d,TTC染色观察脑梗死体积变化;再灌注24h,Western blotting检测HIF-1α及其下游基因的表达变化;制备脑组织切片分别作Nissl染色、免疫组织化学染色及原位缺口末端标记(TUNEL)。结果2ME2组神经功能较MCAO及DMSO组有明显改善(P<0.05),同时,2ME2组梗死面积明显减小(P<0.05)。Western blotting结果显示,HIF-1α的表达经2ME2治疗后降低,其下游基因VEGF、BNIP3及Caspase-3的表达有同样的变化。Nissl染色可见2ME2治疗组皮质神经元结构较清晰,胞体肿胀、核固缩、核溶解程度较模型组及假性治疗组明显减轻,淡染区域减小;免疫组织化学法观察到2ME2组HIF-1α、Caspase-3、BNIP3、VEGF及TUNEL标记的阳性细胞数明显减少(P<0.05)。结论2ME2可能通过降低HIF-1α水平并下调其下游的BNIP3和VEGF的表达,降低血脑屏障的通透性并减少凋亡因子Caspase-3的作用,发挥神经元的保护作用。     

ApoE肽段预处理通过调节c-jun氨基端激酶阻抑小鼠脑缺血再灌后神经细胞的凋亡

目的:为探讨外源性载脂蛋白E(apoE)肽段对局灶性脑缺血再灌(I/R)的保护机制,观察apoE-1410拟肽对I/R小鼠脑组织磷酸化c-jun氨基端激酶(JNK)表达变化的影响。方法:实验选用160只雄性ICR小鼠,随机分为3组:假手术对照组(sham组),模型组(I/R组),apoE治疗组(apoE组),采用可逆性大脑中动脉栓塞(MCAO)模型,术后行神经功能评分。I/R3、6、12、24、48h行HE染色观察皮质区神经细胞的形态变化,并计算存活神经元的数目。利用WesternBlot法、免疫组织化学法检测p-c-jun的表达,行TUNEL法检测凋亡细胞数。结果:与对照组比较,模型组小鼠神经功能评分均降低,I/R12h后存活神经元数目明显减少;p-c-jun阳性反应术后3、6、12、24h显著增高(P0.05);随缺血时间延长,凋亡细胞增多,并于48h达高峰(P0.05)。与模型组比较,治疗组小鼠神经功能评分增加,各时相点p-c-jun和TUNEL表达均不同程度下调(P0.05)。I/R3h至48h皮质区p-c-jun表达与TUNEL呈正相关(r=0.716,P0.01)。结论:缺血侧皮质区p-c-jun表达的增强可诱导I/R后神经细胞凋亡;拟apoE-1410肽对I/R具有一定的治疗作用,其机制之一可能是通过抑制JNK活化实现的。     

Exercise preconditioning reduces neuronal apoptosis in stroke by up-regulating heat shock protein-70 (heat shock protein-72) and extracellular-signal-regulated-kinase 1/2

Exercise preconditioning induces neuroprotection after stroke. We investigated the beneficial role of heat shock protein-70 (HSP-70) and phosphorylated extracellular-signal-regulated-kinase 1/2 (pERK 1/2), as they pertain to reducing apoptosis and their influence on Bcl-x_L, Bax, and apoptosis-inducing factor (AIF) in rats subjected to ischemia and reperfusion. Adult male Sprague–Dawley rats were subjected to 30 min of exercise on a treadmill for 1, 2, or 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament. Protein levels of HSP-70, pERK 1/2, Bcl-x_L, Bax, and AIF were analyzed using Western blot. Neuroprotection was based on levels of apoptosis (TUNEL) and infarct volume (Nissl staining). Immunocytochemistry was used for cellular expression of HSP-70 and pERK 1/2. Significant (P<0.05) up-regulation of HSP-70 and pERK 1/2 after 3 weeks of exercise coincided with significant (P<0.05) reduction in neuronal apoptosis and brain infarct volume. Inhibition of either one of these two factors showed a significant (P<0.05) reversal in the neuroprotection. Bax and AIF were down-regulated, while levels of Bcl-x_L were up-regulated in response to stroke after exercise. Inhibiting HSP-70 or pERK 1/2 reversed this resultant increase or decrease. Our results indicate that exercise diminishes neuronal injury in stroke by up-regulating HSP-70 and ERK 1/2.     

脑缺血再灌注后大鼠海马CA1区p-JNK表达和Bax的相关性的试验研究

目的:观察大鼠脑缺血再灌注后海马CA1区活化的JNK蛋白的表达情况,探讨缺血性脑损伤后神经细胞凋亡相关机理.方法:参照Zea Longa报道的线栓法制备缺血再灌注动物模型,随机将雄性SD大鼠分为正常对照组、缺血再灌注组及假手术对照组.并分别在不同时间点断头取脑制作标本,连续切片作p-JNK、Bax免疫组化染色及HE染色.结果:脑缺血再灌注后海马CA1区p-JNK表达与Bax的表达呈正相关(r=0.838,P＜0.01).p-JNK明显表达时间(2h)略早于Bax的表达,且产生的高峰时间亦稍早.结论:海马CA1区p-JNK表达与Bax的表达呈正相关.     

Neuroprotective effects of olprinone after cerebral ischemia/reperfusion injury in rats

Olprinone hydrochloride, a specific phosphodiesterase III inhibitor, has anti-inflammatory effects in addition to its inotropic and vasodilatory effects. The purpose of this study was to examine the beneficial effects of olprinone on cerebral ischemia reperfusion injury. In the present study, we examined the detailed mechanisms underlying the inhibitory effects of olprinone on inflammatory and apoptotic responses induced by middle cerebral artery occlusion (MCAo) in rats. Focal cerebral ischemia was induced by transient MCAo in the right hemisphere, via the external carotid artery into the internal carotid to block the origin of the median carotid artery. The rats were subjected to artery occlusion (2 h) followed by reperfusion (22 h). Olprinone was administered 5 min before reperfusion. MCAo-induced cerebral ischemia was associated with an increase in inducible nitric oxide synthase expression, nitrotyrosine formation, as well as IL-1β expression and ICAM-1 expression in ischemic regions. Olprinone treatment showed marked reduction in infarct size compared with control rats. These expressions were markedly inhibited by olprinone treatment. We also demonstrated that olprinone reduces levels of apoptosis (TUNEL, Bax and Bcl-2 expression) resulting in a reduction in the infarct volume in ischemia-reperfusion brain injury. Based on these findings we propose that olprinone would be useful in lowering the risk of damage or improving function in ischemia-reperfusion brain injury-related disorders.     

AT1受体自身抗体对糖尿病肾病大鼠肾脏细胞凋亡及JNK表达的作用

 目的:探讨血管紧张素Ⅱ1型受体自身抗体（angiotensin Ⅱ type 1 receptor autoantibody,AT1-AA）对糖尿病肾病（diabetic nephropathy,DN）大鼠肾脏细胞凋亡及内质网应激（endoplasmic reticulum stress,ERS）相关的JNK表达的作用。方法:高糖高脂饮食联合小剂量链脲佐菌素腹腔注射制备DN大鼠模型,采用ELISA法检测大鼠AT1-AA阳性率,根据检测结果随机选择AT1-AA阳性和AT1-AA阴性大鼠共12只纳入DN组,同时选择6只正常大鼠纳入NC组;TUNEL法检测肾脏细胞凋亡;Western blotting技术测定肾组织ERS标志蛋白葡萄糖调节蛋白78 （GRP78）及凋亡蛋白p-JNK的表达水平。结果:DN组大鼠肾脏细胞凋亡率较NC组显著升高,且AT1-AA阳性大鼠凋亡率明显高于AT1-AA阴性大鼠（P<0.01）。Western blotting结果显示,GRP78和p-JNK蛋白在DN组大鼠肾组织中的水平较NC组显著升高,AT1-AA阳性DN大鼠肾组织中,前述蛋白的改变较AT1-AA阴性DN大鼠更为明显（P<0.05）。结论: AT1-AA可诱导DN大鼠肾脏ERS反应,并通过ERS相关的JNK凋亡途径介导肾脏细胞凋亡,损害肾脏功能。     

High levels of histidine decarboxylase in the striatum of mice and rats

Stachybotrys microspora triprenyl phenol-7 (SMTP-7) is a novel fibrinolytic agent with anti-inflammatory effect. Previous study demonstrated that SMTP-7 further ameliorated infarction volume in a mouse embolic stroke model compared with tissue type plasminogen activator (tPA), but the reason SMTP-7 has more beneficial effect than tPA has not yet been determined. In the present study, we investigated whether SMTP-7 has an intrinsic neuroprotective effect against transient focal cerebral ischemia (tFCI). Sprague-Dawley rats were subjected to tFCI by intraluminal middle cerebral artery occlusion for 2 h. Following induction of tFCI, rats were randomized into two groups based on the agent administered: SMTP-7 group and vehicle group. We examined cerebral infarction volume 24 h after reperfusion, and evaluated superoxide production, the expressions of nitrotyrosine and matrix metalloproteinase-9 (MMP-9), which play major roles in secondary brain injury and hemorrhagic transformation. The findings showed that SMTP-7 significantly suppressed superoxide production, the expression of nitrotyrosine and MMP-9 after tFCI, and consequently attenuated ischemic neuronal damage. These results suggest that SMTP-7 has an intrinsic neuroprotective effect on ischemia/reperfusion injury through the suppression of oxidative stress and MMP-9 activation.     

NAD(+) administration decreases ischemic brain damage partially by blocking autophagy in a mouse model of brain ischemia

Nicotinamide adenine dinuleotide (NAD(+)) plays critical roles in multiple biological functions. Previous studies have indicated that NAD(+) treatment decreases oxidative stress-induced death of primary neurons and astrocytes. Intranasal administration of NAD(+) also reduces brain damage in a rat model of transient focal brain ischemia. However, the mechanisms underlying this protective effect remain unknown. In this study, we used a mouse model of brain ischemia to test our hypothesis that NAD(+) decreases ischemic brain damage partially by preventing autophagy. Adult male mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 90min, and NAD(+) was administered intraperitoneally (i.p.) immediately after reperfusion started. We found that administration with 50mg/kg NAD(+) led to significant decreases in infarct size, edema formation, and neurological deficits at 48h after ischemia. NAD(+) administration also significantly decreased brain ischemia-induced autophagy in the cortex and hippocampus. We further found that prevention of autophagy by 3-methyladenine (3-MA), a selective autophagy inhibitor, significantly reduced ischemic brain damage, suggesting an important role of autophagy in the ischemic brain injury in our animal model. Collectively, our findings have suggested that NAD(+) administration decreases ischemic brain damage at least partially by blocking autophagy. This is the first suggested mechanism regarding the protective effects of NAD(+) in cerebral ischemia, which further highlights the promise of NAD(+) for treating brain ischemia.     

mTOR activates hypoxia-inducible factor-1α and inhibits neuronal apoptosis in the developing rat brain during the early phase after hypoxia-ischemia

The mammalian target of rapamycin (mTOR) exerts neuroprotective effects under hypoxic or ischemic conditions. To explore whether mTOR participates in neuroprotective signaling through regulation of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and neuronal apoptosis in developing rat brain with hypoxia-ischemia (HI), we operated on postnatal day 10 rats by ligating the common carotid artery followed by exposure to systemic hypoxia. Brains were collected at various intervals to detect the expression of mTOR, phosphorylated mTOR (p-mTOR), HIF-1α, VEGF and cleaved caspase 3 (CC3), using immunohistochemistry and Western blot analysis. We also used terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) to detect neuronal apoptosis. The p-mTOR protein expression increased at 2 h after HI, peaked at 8 h, lasted 24 h, and then dropped to the basal level. Also, the expression of HIF-1α and VEGF was significantly enhanced and peaked at 8 h after HI. Up-regulated expression of CC3 was observed at 2 h, peaked at 24 h, and lasted 72 h after HI. Increased neuronal apoptosis is associated with reduced HIF-1α and VEGF expression. Furthermore, pretreatment with rapamycin, a mTOR specific inhibitor, significantly inhibited HIF-1α and VEGF protein after HI. The expression of CC3 and the number of TUNEL-positive cells were up-regulated at 8 h and down-regulated at 24 h after HI in the rapamycin-treated group. Our findings suggest that mTOR may participate in the regulation of HIF-1α, VEGF and neuronal apoptosis, serving neuroprotective functions after HI in developing rat brain.