白三烯受体拮抗剂ONO-1078对大鼠短暂性全脑缺血的神经保护作用

AIM: To determine whether ONO-1078 {pranlukast, 4-oxo-8-[p-(4-phenylbutyloxy)benzoyl-amono]-2-(tetrazol-5-yl)-4H-1-benzopyran hemihydrate), a potent leukotriene receptor antagonist, possesses a neuroprotective effect on global cerebral ischemia in rats, and to explore its possible mechanism of action. METHODS: Transient global cerebral ischemia was induced by four-vessel occlusion for 10 min and followed by 72-h reperfusion. ONO-1078(0.03-0.3mg/kg) and edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one, a neuroprotective agent) 10 mg/kg were ip injected 30 rain before ischemia and 1 h after reperfusion, and once a day afterward. Neurological outcome was evaluated before ischemia and 24, 48, 72 h after reperfusion. Neuron density, the expressions of N-methyl-D-aspartate (NMDA) receptor subunit proteins (NR1, NR2A, NA2B) and vascular cell adhesion molecule 1 (VCAM-1) in the cerebral cortex and hippocampus were measured at 72h after reperfusion. RESULTS: ONO-1078 (0.1,0.3mg/kg) and edaravone (10 mg/kg) improved ischemia-induced neurological deficiency and reduced neuron death.ONO-1078 (0.1, 0.3mg/kg) significantly inhibited the enhanced expression of NMDA receptor subunit protein NR2A in the cortex and VCAM-1 in the hippocampus of ischemic rats. CONCLUSION: ONO-1078 possesses a neuroprotective effect on global cerebral ischemia in rats, and its mechanism may be partly related to the inhibition of the upregulation of NR2A and VCAM- 1 in different regions of the brain.     

ONO-1078 reduces NMDA-induced brain injury and vascular cell adhesion molecule-1 expression in rats

Aim: To determine whether ONO-1078 (pranlukast), a potent cysteinyl leukotriene receptor 1 （CysLT1） antagonist, has an effect on N-methyl-D-aspartate (NMDA)-induced brain injury and vascular cell adhesion molecule-1 (VCAM-1) expression in rats. Methods: Brain injury was induced by direct microinjection of NMDA (0.3μmol in 1μL of sterile 0.1mol/L PBS, pH 7.4) into the cerebral cortex. The lesion volume (area), brain edema and neuron density were assessed by an image analyzer and the expression of VCAM-1 in the cortex was detected by Western blot 24h after NMDA injection. ONO-1078(0.03, 0.1, or 0.3mg/kg) and edaravone (MCI-186, 10mg/kg), a neuroprotective agent, were ip injected 30min before and after NMDA injection. Results: NMDA microinjection produced well-defined focal lesions (Figure 1) dose- and time-dependently. ONO-1078(0.1, 0.3mg/kg) and edaravone (10mg/kg) decreased the total lesion volume, lesion area and brain edema induced by NMDA. Furthermore, ONO-1078 (0.1, 0.3mg/kg) significantly inhibited the enhanced expression of VCAM-1 in the injured cortices, but edaravone did not have this effect. Conclusion: CysLT1 receptor antagonist ONO-1078 attenuates NMDA-induced brain damage in rats, and this might relate to the attenuation of NMDA receptor-dependent neurotoxicity and the inhibition of the upregulation of VCAM-1 expression.     

白三烯受体拮抗剂ONO—1078对大鼠局灶性脑缺血的神经保护作用

AIM: To determine whether ONO-1078 (pranlukast), a potent leukotriene receptor antagonist, has neuroprotective effect on focal cerebral ischemia in the rat. METHODS: Focal cerebral ischemia was induced by 30 min of middle cerebral artery (MCA) occlusion and followed by 24 h reperfusion. ONO-1078 (0.003-1.0 mg/kg) or vehicle (saline 1 mL/kg) was ip injected 30 min before MCA occlusion and 2 h after reperfusion. The neurological score, infarct volume, neuron density (in cortex, hippocampus, and striatum), brain edema, and albumin exudation around the vessels were determined 24 h after reperfusion. RESULTS: ONO-1078 slightly improved the neurological deficiency, and dramatically decreased infarct volume and neuron loss which showed a bell shaped dose response effect with highest effect at doses of 0.01-0.3 mg/kg. Enlargement of the ischemic hemisphere and albumin exudation were inhibited at doses of 0.01-1.0 mg/kg. CONCLUSION: ONO-1078 has the protective effect on focal cerebral ischemia in rats, which is partially attributed to the inhibition of brain edema. This may represent a novel approach to the treatment of acute cerebral ischemia with cysteinyl leukotriene receptor antagonists.     

白三烯受体拮抗剂ONO-1078对内皮素-1诱导的大鼠局灶性脑缺血的保护作用

目的观察白三烯受体拮抗剂ONO-1078对内皮素-1诱导的大鼠局灶性脑缺血的保护作用。方法向大脑中动脉附近微量缓慢注射内皮素-1(120 pmol,6 μL,>6 min),诱导大鼠局灶性脑缺血模型,在注射内皮素-1前1 h ip ONO-1078(0.1 mg·kg^-1)。观察神经症状、脑水肿程度、脑梗死体积、纹状体和皮层的存活神经元数的变化。结果 脑内微量注射内皮素-1引起动物出现明显神经症状、脑梗死、脑水肿及皮层和纹状体的存活神经元减少。预先ip ONO-1078显著抑制脑水肿,减小脑梗死体积,增加纹状体和皮层的存活神经元数,可减轻神经症状,但无显著意义。结论ONO-1078对内皮素-1诱导的脑缺血损伤有保护作用,白三烯参与了脑缺血后的组织损伤过程。     

白三烯拮抗剂ONO-1078对小鼠局灶性脑缺血的保护作用

AIM　To determine whether ONO-1078 {pranlukast, 4-oxo-8-［p-(4-phenylbutyloxy) benzoyl-amino]-2-(tetrazol-5-yl)-4H-1-benzopyran hemihydrate}, a potent leukotriene antagonist, has protective effect on focal cerebral ischemia in mice. METHODS　Focal cerebral ischemia was induced by permanent middle cerebral artery (MCA) occlusion in mice. ONO-1078 (0.01, 0.05, 0.10 mg·kg^-1), dexamethasone (0.5 mg·kg^-1), nimodipine (0.2 mg·kg^-1) or saline (control) were injected ip once daily for 3 days, and 30 min before MCA occlusion. Twenty-four hours after cerebral ischemia, the neurological scores were evaluated, infarct volumes and areas of the right and left cerebral hemispheres were measured by computer imaging analysis. RESULTS　ONO-1078, dexamethasone and nimodipine reduced the neurological scores. ONO-1078 and dexamethasone reduced the ratio of right/left hemisphere area, indicating inhibition of brain edema, while nimodipine showed no effect. ONO-1078 dose-dependently reduced infarct size, and dexamethasone and nimodipine showed the same effect. CONCLUSION　ONO-1078 showed protective effect on focal cerebral ischemia. This may represent a novel approach to the treatment of acute cerebral ischemia.     

半胱氨酰白三烯受体拮抗剂pranlukast对小鼠局灶性脑缺血的治疗作用

目的　观察半胱氨酰白三烯受体拮抗剂pranlukast(ONO 10 78)在小鼠局灶性脑缺血后的治疗作用。方法　采用大脑中动脉阻塞造成小鼠持续性局灶性脑缺血 ,缺血后1、6、2 4h分别给小鼠腹腔注射 pranlukast或依达拉奉 ,观察药物对缺血 2 4、4 8h后的神经功能缺损症状 ,4 8h后的脑梗死体积、两侧大脑半球比值、神经元密度的影响。结果　Pranlukast 0 1、0 2mg·kg-1及依达拉奉 3、10mg·kg-1均能减轻神经症状、减小脑梗死体积、降低缺血侧 /非缺血侧大脑半球比值、减轻海马CA1区、皮层和纹状体的神经元密度降低。结论　Pranlukast脑缺血后给药对脑损伤有治疗作用 ,提示有治疗缺血性脑卒中的临床前景。     

新型神经保护剂TQ0701-2对大鼠脑缺血再灌注损伤的保护作用

目的：研究新型神经保护剂TQ0701-2对大鼠脑缺血再灌注损伤的保护作用。方法：将120只雄性SD大鼠随机分为假手术组、模型组、依达拉奉组（3.0mg/kg）以及TQ0701-2高剂量组（6.0mg/kg）、中剂量组（3.0mg/kg）、低剂量组（1.5mg/kg）。假手术组仅进行手术而不造成缺血状态,其余各组均采用Longa线栓法制备大鼠MCAO模型,在缺血2h后进行再灌注。TQ0701-2三个剂量组和依达拉奉组分别在缺血前30min以及再灌注0、2h尾静脉注射TQ0701-2和依达拉奉,假手术组和模型组则给予等量的生理盐水。再灌注24h后观察大鼠神经功能损伤症状、脑组织梗死率以及病理组织学的改变。结果：模型组大鼠神经功能损伤严重,脑组织梗死率也明显增高（P〈0.01vs假手术组）。与依达拉奉的保护作用相同,TQ0701-2高中低三个剂量均能显著降低MCAO大鼠的神经功能评分和脑组织梗死率（P〈0.01vs模型组）,并且三个剂量的改善作用是随着浓度增大而增强的,具有剂量相关性。另外,TQ0701-2对大鼠脑缺血再灌注所致的神经元变性、坏死也有一定的保护作用。结论：研究表明,依达拉奉衍生物TQ0701-2对大鼠的脑缺血再灌注损伤有明显的神经保护作用。     

Pranlukast, a cysteinyl leukotriene receptor 1 antagonist, protects mice against brain cold injury

We have reported the neuroprotective effect of cysteinyl leukotriene receptor 1 (CysLT1) antagonists on cerebral ischemia. Here, we further determined the protective effect of pranlukast, a CysLT1 receptor antagonist, on brain cold injury in mice. Brains were injured by placing a cooled metal probe on the skull surface for 30 s. We found that pranlukast significantly reduced cold-induced lesion volume (0.3 mg/kg) and the percentage increase in lesioned hemisphere volume (0.03-0.3 mg/kg) 24 h after injury, but did not show any effect 72 h after injury. Pranlukast also significantly inhibited neuron loss 24 h (0.1 mg/kg) and 72 h (0.1-0.3 mg/kg) after injury, and decreased the density of degenerated neurons 24 h (0.01-0.3 mg/kg) and 72 h (0.03-0.3 mg/kg) after injury. In addition, pranlukast (0.1-0.3 mg/kg) significantly reduced endogenous IgG exudation both 24 h and 72 h after injury. Thus, this study indicates the protective effect of pranlukast on brain cold injury.     

NVP-AAM077和Ro25-6981对全脑缺血小鼠海马神经元损伤及BDNF表达的影响

目的探讨N-甲基-D-天冬氨酸受体(NMDA)亚基NR2A和NR2B特异性拮抗剂对脑缺血/再灌注后海马CA1区神经元损伤的不同影响及其可能机制。方法制作三动脉阻断(3-VO)小鼠全脑缺血模型,小鼠随机分为假手术组、脑缺血/再灌注(I/R)对照组、NVP-AAM077(NVP)干预组和Ro25-6981(Ro)干预组;应用Fluoro-JadeB(F-JB)和Nissl染色检测海马神经元变性死亡和存活情况,Western blot对脑源性神经生长因子(BDNF)蛋白表达水平进行定量分析。结果①小鼠全脑缺血12min/再灌注3d后,海马CA1区出现选择性迟发性神经元死亡,NVP干预组增加了缺血所致的海马神经元死亡(P<0.05),而Ro干预组CA1区神经元存活数量明显多于缺血/再灌注组(P<0.01);②NVP干预能明显下调缺血/再灌注所致的海马组织BDNF蛋白表达升高(P<0.01),而Ro干预能明显上调BDNF蛋白的表达(P<0.05)。结论 NMDA受体亚基NR2A和NR2B在小鼠脑缺血/再灌注损伤中具有不同的作用,其机制可能与调节BDNF表达改变有关。     

Montelukast, a cysteinyl leukotriene receptor-1 antagonist, dose- and time-dependently protects against focal cerebral ischemia in mice

Our previous studies showed that cysteinyl leukotriene receptor-1 (CysLT1) antagonist pranlukast has a neuroprotective effect on cerebral ischemia in rats and mice. However, whether the neuroprotective effect of pranlukast is its special action or a common action of CysLT1 receptor antagonists remains to be clarified. This study was performed to determine whether montelukast, another CysLT1 receptor antagonist, has the neuroprotective effect on focal cerebral ischemia in mice, and to observe its dose- and time-dependent properties. Permanent focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). Montelukast was injected intraperitoneally either as multiple doses (once a day for 3 days and 30 min before MCAO) or as a single dose (at 30 min before, 30 min after, or 1 h after MCAO), respectively, and pranlukast and edaravone were used as controls. The neurological deficits, infarct volumes, brain edema, neuron density, and Evans blue extravasation in the brain were determined 24 h after MCAO. Pretreatments with multiple doses or a single dose of montelukast (0.1 and 1.0 mg/kg) before MCAO significantly attenuated all the ischemic insults. Post-treatment with a single dose of montelukast (0.1 and 1.0 mg/kg) at 30 min after MCAO also significantly decreased brain edema and infarct volume, but not neurological deficits. However, post-treatment with a single dose of montelukast at 1 h after MCAO had no significant effect. Pranlukast showed the same effects as montelukast, but edaravone attenuated the ischemic insults only with multiple doses before MCAO. Thus, montelukast has a dose- and time-dependent neuroprotective effect on permanent focal cerebral ischemia in mice, with an effective dose range of 0.1-1.0 mg/kg and a therapeutic window of 30 min. These findings further support the therapeutic potential of CysLT1 receptor antagonists in the treatment of cerebral ischemia at earlier phases.     

依达拉奉、米诺环素及ONO-1078对缺氧缺糖诱导大鼠海马脑片电生理改变的作用

目的建立离体海马脑片缺氧缺糖(OGD)电生理变化模型,观察依达拉奉、米诺环素和ONO-1078 {pranlukast,4-氧-8-［对-(4-苯丁氧基)苯甲酰氨基］-2-(5-四氮基)-4H-1-苯并吡喃半水化合物}的神经保护作用。方法 大鼠海马脑片以无氧无糖处理,记录脑片群峰电位(PS),部分实验以TTC染色观察脑片活性。结果OGD处理4 min为最佳损伤条件,1 h后可恢复至基础水平的(29±6)%。自由基清除剂依达拉奉(1和10 μmol·L^-1)明显增强PS波的恢复;抗炎药米诺环素(10 μmol·L^-1)和白三烯受体拮抗剂ONO-1078(1 μmol·L^-1)无显著恢复作用;阳性对照药氯胺酮也浓度依赖性促进PS恢复。结论4 min OGD为离体海马脑片缺血电生理变化的可行模型;依达拉奉对OGD脑片损伤有浓度依赖性保护作用,而米诺环素和ONO-1078未显示保护作用。     

In vivo pharmacologic profile of ONO-1078: a potent, selective and orally active peptide leukotriene (LT) antagonist.

We investigated the in vivo antagonistic activity of ONO-1078 against peptide leukotrienes (LTs) in guinea pigs. ONO-1078, when administered p.o. (0.3-3 mg/kg), caused a dose-dependent reduction of LTC4-, LTD4- and LTE4-induced bronchoconstriction, LTD4-induced airway microvascular leakage and LTD4-induced increase in cutaneous vascular permeability. When administered intravenously, ONO-1078 (3-30 micrograms/kg) inhibited these responses approximately 200-600 fold more potently than FPL55712. When guinea pigs were treated with indomethacin to examine the antagonism of ONO-1078 on the direct action against peptide LTs, intravenous (3-30 micrograms/kg) and oral (0.3-3 mg/kg) administration of ONO-1078 also inhibited LTC4- and LTD4-induced bronchoconstriction, and its activity was approximately 300-500 fold more potent than that of FPL55712. ONO-1078 (10 mg/kg, i.v.) had no inhibitory effect on bronchoconstrictions induced by histamine, acetylcholine, serotonin, arachidonic acid, LTB4, prostaglandin (PG) F2 alpha, PGD2, 9 alpha, 11 beta-PGF2, a stable thromboxane A2 mimetic agent and platelet activating factor. Furthermore, oral administration of ONO-1078 (1-10 mg/kg) inhibited slow-reacting substance of anaphylaxis mediated bronchoconstriction induced by antigen in a dose-dependent manner. These results indicate that ONO-1078 is an extremely potent, selective and orally active peptide LT antagonist and that oral administration of ONO-1078 antagonizes not only exogenously administered peptide LTs but also endogenous peptide LTs.     

Role of the NMDA receptor subunit in the expression of the discriminative stimulus effect induced by ketamine.

Ketamine, which is a non-competitive NMDA receptor antagonist, has been used as a dissociative anesthetic agent. However, chronic use of ketamine produces psychotomimetic effects, such as nightmares, hallucination and delusion. Therefore, the present study was designed to ascertain the role of the NMDA receptor and sigma receptor in the discriminative stimulus effect induced by ketamine. Fischer 344 rats were trained to discriminate between ketamine (5 mg/kg, i.p.) and saline under a fixed-ratio 10 food-reinforced procedure. Non-competitive antagonists for both NR2A- and NR2B-containing NMDA receptors, such as phencyclidine (0.1--1 mg/kg, i.p.) and dizocilpine (3--30 microg/kg, i.p.), and the NR2A-containing NMDA receptor-preferred antagonist dextromethorphan (3--56 mg/kg, i.p.) fully substituted for the ketamine cue in a dose-dependent manner. By contrast, the NR2B-containing NMDA receptor antagonist ifenprodil (5--20 mg/kg, i.p.) exhibited no generalization. Additionally, the competitive NMDA antagonist 3-[(+/-)-2-carboxypiperazine-4-yl] propyl-1-phosphonic acid ((+/-)-CPP; 0.3--5.6 mg/kg, i.p.) and a sigma receptor ligand DTG (0.3--3 mg/kg, s.c.) displayed no generalization to the ketamine cue. These results suggest that NR1/NR2A subunit containing NMDA antagonism may be critical for the production of the ketamine cue.     

The edaravone and 3-n-butylphthalide ring-opening derivative 10b effectively attenuates cerebral ischemia injury in rats

Aim:

Compound 10b is a hybrid molecule of edaravone and a ring-opening derivative of 3-n-butylphthalide (NBP). The aim of this study was to examine the effects of compound 10b on brain damage in rats after focal cerebral ischemia.

Methods:

SD rats were subjected to 2-h-middle cerebral artery occlusion (MCAO). At the onset of reperfusion, the rats were orally treated with NBP (60 mg/kg), edaravone (3 mg/kg), NBP (60 mg/kg)+edaravone (3 mg/kg), or compound 10b (70, 140 mg/kg). The infarct volume, motor behavior deficits, brain water content, histopathological alterations, and activity of GSH, SOD, and MDA were analyzed 24 h after reperfusion. The levels of relevant proteins in the ipsilateral striatum were examined using immunoblotting.

Results:

Administration of compound 10b (70 or 140 mg/kg) significantly reduced the infarct volume and neurological deficits in MCAO rats. The neuroprotective effects of compound 10b were more pronounced compared to NBP, edaravone or NBP+edaravone. Furthermore, compound 10b significantly upregulated the protein levels of the cytoprotective molecules Bcl-2, HO-1, Nrf2, Trx, P-NF-κB p65, and IκB-α, while decreasing the expression of Bax, caspase 3, caspase 9, Txnip, NF-κB p65, and P-IκB-α.

Conclusion:

Oral administration of compound 10b effectively attenuates rat cerebral ischemia injury.     

NR2A反义寡核苷酸对短暂性脑缺血/再灌注大鼠海马神经元损伤的保护作用

目的探讨NMDA受体亚单位2A(NR2A)反义寡核苷酸在短暂性脑缺血/再灌注大鼠海马神经元损伤中的保护作用,为研制和开发针对NR2A的特异性新药提供理论基础和形态学依据。方法健康♂SD大鼠随机分为正常对照组、假手术对照组和缺血/再灌注组。经生理盐水、错义寡核苷酸和反义寡核苷酸预处理后,以四血管阻断法建立短暂性全脑缺血(15min)/再灌注(1、2、3和5d)动物模型。在确定的时间点进行灌注固定、取材、石蜡包埋和组织切片(片厚8μm),然后行TUNEL反应、焦油紫染色、原位杂交染色以及免疫组织化学染色。结果短暂性脑缺血/再灌注(I/R)3d,大鼠海马CA1区出现大量的凋亡阳性细胞;I/R5d大鼠海马CA1区细胞严重受损,与对照组相比二组差异具有显著性(P<0.05)。经NR2A反义寡核苷酸预处理后,I/R3d和I/R5d海马CA1区的细胞凋亡和细胞损伤明显减轻,与对照组相比二组差异具有显著性(P<0.05)。NR2A反义寡核苷酸能抑制I/R1d NR2A mRNA表达和I/R2d蛋白质表达,与对照组相比差异具有显著性(P<0.05)。结论短暂性全脑缺血后,NR2A反义寡核苷酸能明显地减轻缺血诱导的大鼠海马CA1区细胞凋亡和细胞损伤,且这种作用与NR2A反义寡核苷酸特异性抑制NR2A及其mRNA的表达密切相关。     

Neuroprotection of selenite against ischemic brain injury through negatively regulating early activation of ASK1/JNK cascade via activation of PI3K/AKT pathway

AIM: To investigate whether selenite, a known antioxidant, could decrease the activation of apoptosis signal regulating kinase 1/c-jun N-terminal kinase (ASK1/ JNK) signaling cascade in cerebral ischemia/reperfusion (I/R) by activating the phosphatidylinositol 3-kinase (PI3K)/AKT pathway in rat hippocampi, and the neuroprotective effect of selenite against ischemic injury after 15 min of transient brain ischemia. METHODS: Transient global brain ischemia was induced by 4-vessel occlusion into adult male Sprague-Dawley rats weighing 250-300 g. The rats were pretreated only with selenite (0.3 mg/kg dissolved in 0.9% saline) every 24 h for 7 d by means of intravenous injection of the tail or combined with LY294002 from d 5 by left cerebral ventricle injection before surgery. RESULTS: Selenite significantly increased AKT1 activation and decreased the activation of ASK1/ JNK cascade via phosphorylating ASK1 at Ser-83 residue by AKT1 during early reperfusion after 15 min transient global brain ischemia. On the contrary, combined pretreatment of the rats with LY294002 (a specific PI3K inhibitor) and selenite significantly inhibited the effects solely with selenite. CONCLUSION: The activation of the pro-apoptotic ASK1/JNK cascade, which is closely associated with oxidative stress, could be suppressed by selenite through activating the antiapoptotic PI3K/AKT pathway during early reperfusion after cerebral ischemia in rat hippocampi.     

Substitution for PCP, disruption of prepulse inhibition and hyperactivity induced by N-methyl-D-aspartate receptor antagonists: preferential involvement of the NR2B rather than NR2A subunit

The non-competitive NMDA receptor antagonist phencyclidine (PCP) is known to produce a discriminative stimulus in rats. The first aim of the present study was to investigate which NMDA receptor subtype(s) is involved in this effect of PCP. Rats were trained to discriminate PCP (2 mg/kg; i.p.) from saline in a two lever operant task. The NMDA channel blocker, (+)MK-801 (0.1 mg/kg; i.p.) and the competitive NMDA receptor antagonist SDZ 220-581 (3 mg/kg; i.p.) produced 76% of PCP-lever selection (ED50=0.045 and 2 mg/kg, respectively), whereas their respective inactive enantiomers (-)MK-801 (0.025-0.1 mg/kg) and SDZ 221-653 (2-5 mg/kg) induced less than 30% of PCP-appropriate responding. Another competitive NMDA antagonist, SDZ EAB-515 (30 mg/kg; i.p.), induced 63% of PCP-lever responding (ED50=23.48 mg/kg). The selective antagonist of NMDA receptors containing the NR1A/NR2B-subunits Ro 25-6981 (20 mg/kg; i.p.) resulted in a complete substitution (more than 80% of PCP-lever selection) for PCP (ED50=8.59 mg/kg). In contrast, the NR1A/NR2A NMDA receptor-preferring antagonist NVP-AAM077 (2-10 mg/kg; i.p.) failed to produce PCP-like discriminative stimuli. At high doses SDZ 220-581 (ED50=2.44), NVP-AAM077 (ED50=8.33) and SDZ EAB-515 (ED50=25.81) decreased the performance of the rats in this operant task. The ability of these NMDA receptor antagonists to disrupt the prepulse inhibition (PPI) of the startle response and to alter locomotor activity was also studied. PCP (0.5-2 mg/kg; s.c.), SDZ 220-581 (0.5-5 mg/kg; s.c.), SDZ EAB-515 (1-30 mg/kg; i.p.) and Ro 25-6981 (5-20 mg/kg; i.p.) disrupted PPI and at high doses produced hyperlocomotion. In contrast, NVP-AAM077 (5-20 mg/kg; i.p.) did not disrupt PPI and reduced locomotor activity. In conclusion, it appears that the NMDA receptor containing the NR2B, rather than the NR2A subunit, may play a major role in the PCP-like discriminative stimulus. In addition, sensory motor gating disturbances associated with NMDA antagonists do not seem to result from a blockade of NR1/NR2A-containing NMDA receptors.     

Competitive binding of postsynaptic density 95 and Ca^2＋-calmodulin dependent protein kinase Ⅱ to N-methyl-D-aspartate receptor subunit 2B in rat brain

AIM: To investigate the interactions among postsynaptic density 95 (PSD-95), Ca^2 -calmodulin dependent protein kinase Ⅱα (CaMKⅡα), and N-methyl-D-aspartate receptor subunit 2B (NR2B) during ischemia and reperfusion in hippocampus of rats. METHODS: Brain ischemia was induced by four-vessel occlusion procedure in rats. Immunoprecipitation and immunoblotting were performed to study the interactions and phosphorylation of proteins. The association-dissociation of PSD-95 and CaMKⅡα to and from N-methyl-D-aspartate (NMDA) receptor induced by ischemia and reperfusion and the effects of 1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenyl-piperazine (KN-62, a selective inhibitor of CaMKⅡ) on these protein interactions were investigated. Coimmunoprecipitation and immunoblotting were performed for the studies of interactions among proteins. RESULTS: The alternations of the binding level of PSD-95 and CaMKⅡα to NR2B during ischemia and reperfusion demonstrated the negative correlation to each other. Pre-administration of KN62 through both cerebral ventricles inhibited the 10min ischemia-induced increase of the binding of PSD-95 to NR2B and, on the contrary, promoted the binding of CaMKⅡα to NR2B. CONCLUSION: PSD-95 competes with CaMKⅡ to bind to NR2B during ischemia and reperfusion in rat hippocampus.     

阿坎酸对大鼠局灶性脑缺血/再灌注神经的保护作用

目的:研究阿坎酸对大鼠局灶性脑缺血-再灌注损伤的神经保护作用.方法:大鼠大脑中动脉栓塞模型参照Longa报道的方法进行.48只SD雄性大鼠随机分为假手术组、模型组、阿坎酸组.缺血2 h后恢复灌注,给药组腹腔注射给药.造模前后进行神经损害严重程度评分(NSS),TTC染色测定梗死面积,HE染色检测脑组织病理变化,应用蛋白质印迹检测大鼠脑组织中NR2B的表达.结果:阿坎酸能明显改善大鼠的神经行为,缩小梗死面积,并使脑组织病理改变减轻.同时,阿坎酸能有效降低NR2B的表达.结论:阿坎酸对局灶性脑缺血／再灌注大鼠有明显的保护作用.     

Effect of melatonin on ischemia reperfusion injury induced by middle cerebral artery occlusion in rats.

Free radicals have been implicated in neuronal injury during ischemia reperfusion in stroke. Therefore, in the present study, melatonin, a potent antioxidant, was studied in male Wistar rats subjected to 2 h of transient middle cerebral artery occlusion. Melatonin (10, 20 and 40 mg/kg i.p.) was administered four times in an animal at the time of middle cerebral artery occlusion, 1 h after middle cerebral artery occlusion, at the time of reperfusion and 1 h after reperfusion. Two hours after reperfusion, rats were euthanized for estimation of oxidative stress markers (malondialdehyde and reduced glutathione). The doses of 20 and 40 mg/kg of melatonin significantly attenuated the raised level of malondialdehyde (287+/-28, 279+/-52 nmol/g wet tissue, respectively) as compared to the levels (420+/-61 nmol/g wet tissue) in vehicle-treated middle cerebral artery-occluded rats. There was an insignificant change in levels of reduced glutathione at these doses (95+/-42, 88.7+/-36 microg/g wet tissue, respectively) as compared to those in the vehicle-treated middle cerebral artery-occluded rats (108.21+/-21 microg/g wet tissue). However, there was an insignificant difference between 20 and 40 mg/kg treated rats. Therefore, the dose of 20 mg/kg i.p. was used to evaluate the neuroprotective effect by using diffusion-weighted imaging (30 min after reperfusion), assessing the neurological deficit (24 h after middle cerebral artery occlusion) and estimating oxidative stress markers (72 h after middle cerebral artery occlusion). In the 20 mg/kg melatonin-treated group, percent ischemic lesion volume on diffusion-weighted imaging was significantly attenuated (9.8+/-3.9) as compared to that in the vehicle-treated group (21.4+/-4.7). The neurological deficit was significantly improved in the melatonin group (1.8+/-0.06) as compared to that in the vehicle-treated (2.9+/-0.38) group. The level of malondialdehyde (321.4+/-31 nmol/g wet tissue) and reduced glutathione (142.6+/-13 microg/g wet tissue) in the melatonin-treated group was also significantly decreased as compared to the level of malondialdehyde (623+/-22 nmol/g wet tissue) and reduced glutathione (226.6+/-19 microg/wet tissue) in the vehicle-treated group. The present study indicates that melatonin has a neuroprotective action in focal ischemia, which may be attributed to its antioxidant property.