异丙酚预处理对大鼠海马神经元凋亡的影响

目的探讨异丙酚预处理对缺氧/复氧后大鼠海马神经元凋亡的影响。方法取离体培养的大鼠海马神经元,随机分成5组:正常组(A)组。CoCl2组(B)组:加入300μmol·L-1(下同)CoCl2处理4h,然后更换正常的培养基培养24h,之后更换无血清的培养基培养。脂肪乳组(C)组:加入10%脂肪乳剂90μl预处理1h后同B组。异丙酚组(D)组:加入100μmol·L-1异丙酚1h后同B组。7-NI组(E)组:如D组,但加入CoCl2的同时加入3·3μl7-NI(25g·L-1)处理4h。MTT法测定细胞增殖,流式细胞技术测定细胞的凋亡。RT-PCR技术检测神经型一氧化氮合酶和凋亡相关基因的表达情况。结果脂肪乳组与CoCl2组比较,各项指标相似(P>0·05);异丙酚可增加神经元的增殖能力,减少凋亡(P<0·05或P<0·01),上调神经型一氧化氮合酶和凋亡抑制基因bcl-2的表达,下调促凋亡基因cyclinD1的表达。而这些调节作用可被神经型一氧化氮合酶抑制剂7-NI抑制(P<0·05或P<0·01)。结论100μmol·L-1异丙酚预处理对缺氧/复氧后大鼠海马神经元有保护作用,神经型一氧化氮合酶和凋亡相关基因在其中起重要作用。     

氯胺酮诱导大鼠海马神经元凋亡及机制

目的 研究氯胺酮对SD大鼠海马神经元的凋亡诱导作用,并探究其作用机制.方法 培养SD大鼠海马神经元细胞,将对数生长期的大鼠海马神经元分为对照组(不加氯胺酮)和实验组(加氯胺酮且其终浓度分别为10、20 μmol/L).24h后,缩胆囊素8肽(CCK-8)法检测细胞存活率,流式细胞术检测细胞凋亡,蛋白质印迹法检测蛋白phospho-细胞外信号调节蛋白激酶(P-ERK)、Bax、Bcl-2的表达.结果 10、20 μmol/L实验组神经元的存活率分别为(73.7±1.5)％和(58.2±2.4)％,明显低于对照组的(97.2±1.8)％(P＜0.05);凋亡率分别为(24.5±7.4)％和(34.7±4.9)％,明显高于对照组的(4.7±2.3)％(P＜0.05);P-ERK、Bax表达量增加,Bcl-2表达量减少.结论 氯胺酮能够诱导大鼠海马神经元凋亡,可能是通过激活P-ERK、改变Bax/Bcl-2比值实现的.     

雌激素对NMDA诱导离体大鼠海马神经元凋亡的作用

目的观察雌激素对NMDA诱导离体海马神经元凋亡的作用,探讨雌激素的神经保护作用机制。方法用形态学鉴定和细胞死亡率的测定以及Western blot方法分析雌激素对NMDA诱导神经元凋亡的作用。结果培养的神经细胞经形态学鉴定绝大多数是神经元,占总细胞数目的81·3%,凋亡细胞百分数为15·1%,NMDA(300μmol·L-1+甘氨酸5μmol·L-1)能明显诱导神经元凋亡,凋亡发生数为31·6%(与对照组相比P<0·05),雌激素(300μmol·L-1)能明显拮抗NMDA的凋亡毒性作用,凋亡发生数为18·2%(与对照组相比P>0·05)。MTT实验测定细胞生存率:NMDA组为70·2%(与对照组相比P<0·05),NMDA+雌激素组为89·7%(与对照组相比P>0·05)。蛋白印迹也显示,caspase-3的活性能被雌激素所抑制。结论雌激素具有神经保护作用,作用机制可能通过抑制凋亡相关酶的活性来实现。实验结果为开发雌激素的临床应用和寻找神经保护作用药物提供实验参考依据。     

氯通道阻断剂对NO诱导离体大鼠海马神经元凋亡的保护作用

目的观察氯通道阻断剂SITS和DIDS对NO诱导的大鼠离体海马神经元凋亡的保护作用。方法离体培养12d的SD大鼠海马神经元,随机分为正常对照组、NO处理组、NO处理后使用氯通道阻断剂组,对各组神经元分别在相应的时间点进行Hoechst荧光染色观察凋亡细胞数和MTT实验定量检测神经元的存活率,Western blot分析凋亡信号分子Caspase-3的变化。结果SITS和DIDS呈剂量依赖性地抑制NO诱导的神经元损伤,并能抑制损伤所引起的Caspase-3的激活,提高神经元的存活率。结论氯通道阻断剂对NO诱导的大鼠海马神经元凋亡有一定的保护作用。     

复方二精灵多糖对谷氨酸诱导的海马神经元凋亡的保护作用

目的探讨中药复方二精灵多糖(EJL)预防阿尔茨海默病的机制。方法实验分为正常对照组、模型(100μmol.L-1谷氨酸诱导)组、阳性对照组(50μmol.L-1多奈哌齐)及EJL实验组(0.5,1.0,2.0及3.0g.L-1)。体外培养9d的海马神经元先用各药物预处理一定时间后,加入谷氨酸。采用MTT法、Hoechst 33258荧光染色、流式细胞术和Western蛋白质印迹法等方法检测细胞凋亡。结果MTT检测发现,随着EJL浓度的增加,细胞的存活率也增加;与模型组〔(59.6±4.6)%〕比较,EJL2.0及3.0g.L-1组细胞存活率明显升高〔(82.8±2.8)%和(89.4±4.1)%;n=3,P<0.05〕。荧光染色观察形态学变化发现,EJL预处理组凋亡细胞明显减少。FITC-Annexin Ⅴ和PI双染,在直方图中可以发现,模型组的凋亡率为32.33%,EJL预处理组则分别为24.33%,22.01%及12.12%。Western蛋白质印迹法结果显示,与模型组比,EJL2.0g.L-1预处理可以显著提高Bcl-2蛋白表达量,减少Bax蛋白表达量。结论EJL对海马神经元有一定的保护作用。     

缺血预适应对大鼠海马神经元凋亡的影响

目的 探讨缺血预适应对缺氧复氧后大鼠海马神经元的影响.方法 用300μmol/L氯化钴预处理大鼠海马神经元2 h,然后更换正常的培养基培养24 h,之后用无血清的培养基培养,建立预适应的细胞模型.四甲基偶氮唑蓝(MTT)法测定细胞增殖,流式细胞术测定细胞凋亡,反转录-聚合酶链反应(RT-PCR)检测凋亡相关基因的表达情...     

氯胺酮对大鼠学习记忆功能及海马神经元的影响

目的了解多次氯胺酮给药对学习记忆功能的影响及机制。方法SD大鼠30只随机分为高剂量组、低剂量组和1个对照组,高、低剂量组大鼠分别予以氯胺酮50和10 mg/kg腹腔注射给药,1次/d,连续7 d。对照组予以等量生理盐水。用水迷宫测试各组大鼠寻找隐匿台的逃避潜伏期和空间搜索能力,原位检测海马神经元凋亡情况,电子显微镜观察神经元超微结构变化。结果高剂量组逃避潜伏期显著延长(P<0.01),并且空间搜索能力明显降低(P<0.01);高剂量组海马神经元凋亡指数显著高于对照组(P<0.01);电子显微镜显示高剂量组海马神经元有明显变性。结论多次使用氯胺酮对学习记忆有损害,这种损害作用可能与海马神经元病变有关。     

芍药苷对醋酸铅诱导海马神经元凋亡及Bcl-2/Bax蛋白表达的影响

目的 探讨芍药苷(paeoniflorin,PF)对醋酸铅诱导海马神经元凋亡及Bcl-2/Bax蛋白表达的影响。方法 分离培养胎鼠海马神经元细胞,细胞免疫荧光染色鉴定纯度。MTT测定海马神经元细胞活力以确定醋酸铅最适造模浓度及时间,同时筛选合适剂量PF干预海马神经元凋亡。依据MTT测定结果,分为空白组、模型组和20,40,80 μmol·L^-1 PF组干预海马神经元细胞,作用24 h后,加醋酸铅染毒,检测细胞色素C (cytochrome C,Cyt-C)含量、线粒体膜电位及细胞内Ca²⁺浓度。流式细胞仪检测细胞凋亡情况,Western blotting测定海马神经元细胞中caspase-3、cleaved-caspase-3、caspase-8、cleaved-caspase-8、caspase-9、cleaved-caspase-9、Bax、Bcl-2蛋白表达水平。结果 细胞免疫荧光染色鉴定结果显示分离培养的细胞为海马神经元细胞,且纯度较高。MTT测定结果显示醋酸铅最适造模浓度及时间为25 μmol·L^-1染毒24 h;PF剂量为20,40,80 μmol·L-1可显著改善海马神经元细胞活性,呈剂量依赖性。与空白组相比,模型组Cyt-C含量、凋亡率、细胞内Ca²⁺浓度显著升高(P<0.01),线粒体膜电位显著降低(P<0.01)。与模型组相比,40 μmol·L^-1 PF组和80 μmol·L^-1 PF组可降低Cyt-C含量、凋亡率、细胞内Ca²⁺浓度(P<0.05或P<0.01),升高线粒体膜电位(P<0.01),20 μmol·L^-1PF组可显著升高线粒体膜电位(P<0.05)。此外,一定剂量的PF可下调cleaved-caspase-3、cleaved-caspase-8、cleaved-caspase-9、Bax蛋白表达,上调Bcl-2蛋白表达。结论 PF可抑制醋酸铅诱导的海马神经元凋亡,可通过调控Bcl-2/Bax蛋白表达发挥神经保护作用。     

阿魏酸钠对硝普钠诱导的原代培养海马神经元凋亡的保护作用

目的:探讨阿魏酸钠(sodium ferulate,SF)对NO供体硝普钠(SNP)引起的大鼠海马神经元凋亡保护作用的可能机制.方法:原代培养的大鼠海马神经元,经终浓度为10～160 μmol·L-1的SF预处理6 h后,用50 μmol·L-1的SNP处理24 h,采用MTT法检测细胞存活率,Hochest 33258荧光染色及DNA琼脂糖凝胶电泳分析等方法检测凋亡,Western blot及RT-PCR检测bcl-2基因表达.结果:不同浓度SF(10～160μmol·L-1)预处理6 h可显著提高神经元的存活率,减少SNP引起的核固缩、凝聚和碎裂现象;DNA凝胶电泳图谱未见典型的"梯子状"改变;增加bcl-2 mRNA及蛋白的表达.结论:SF对NO供体SNP诱导的海马神经元凋亡具有明显的保护作用,其机制可能与增加抗凋亡基因bcl-2表达有关.     

续断提取物对血管性痴呆大鼠学习记忆能力及海马神经元的保护作用

目的 观察续断提取物对血管性痴呆大鼠学习记忆能力及海马神经元的影响.方法 采用反复夹闭、再通双侧颈总动脉的同时于腹腔注射硝普钠,建立大鼠血管性痴呆模型;观察续断提取物对模型大鼠学习记忆能力、血清中超氧化物歧化酶(SOD)的活力、丙二醛(MDA)的含量以及谷胱甘肽过氧化物酶(GSH-Px)水平和海马中Bcl-2、Bax蛋白表达的影响.结果 与模型组比较,中、高剂量续断提取物能提高大鼠的学习记忆能力以及血清中GSH-Px的水平和SOD的活性,降低MDA的含量;增加海马中抗凋亡蛋白Bcl-2的表达和抑制促凋亡蛋白Bax的表达.结论 续断提取物能够改善血管性痴呆大鼠的记忆障碍,对海马神经元具有一定的保护作用.     

Characterization of proteinase-activated receptor 2 signalling and expression in rat hippocampal neurons and astrocytes

Proteinase-activated receptors (PARs1-4) have recently been identified as the molecular entity underlying the cellular effects of serine proteinases. In the present study we have investigated PAR2 signalling, expression and desensitization using cultured and acute slice preparations. Trypsin, SLIGRL and 2f-LIGKV-OH, agonists for PAR2, induced a transient increase in intracellular Ca(2+) levels in both neurons and astrocytes, via activation of the phospholipase C/IP(3) pathway. Furthermore, a single application of trypsin, but not SLIGRL nor 2f-LIGKV-OH, leads to prolonged desensitization of PAR2 responses. PAR2 immunoreactivity was observed in neurons (glutamatergic and GABAergic) and astrocytes within cultures and acute slices, with prominent labelling in neuronal somata and proximal dendrites. Functionally, cultured neurons which exhibited the highest levels of PAR2 labelling, also exhibited the largest Ca(2+) signals upon PAR2 activation. Given the importance of Ca(2+) signalling in hippocampal synaptic plasticity and neurodegeneration, PAR2 may play a key modulatory role in these processes.     

Involvement of cannabinoid CB(2) receptor-mediated response and efficacy of cannabinoid CB(2) receptor inverse agonist, JTE-907, in cutaneous inflammation in mice

Involvement of cannabinoid CB₂ receptor and effect of cannabinoid CB₂ receptor antagonist/inverse agonists on cutaneous inflammation were investigated. Mice ears topically exposed to an ether-linked analogue of 2-arachidonoylglycerol (2-AG-E) or selective cannabinoid CB₂ receptor agonist, {4-[4-(1,1-dimethylheptyl)-2,6-dimethoxy-phenyl]-6.6-dimethyl-bicyclo[3.1.1]hept-2-en-2-yl}-methanol (HU-308), had early and late ear swelling (0–24 h and 1–8 days after exposure, respectively). Both types of responses induced by 2-AG-E were significantly suppressed by oral administration of cannabinoid CB₂ receptor antagonist/inverse agonists, [N-(benzo[1,3]dioxol-5-ylmethyl)-7-methoxy-2-oxo-8-pentyloxy-1,2-dihydroquinoline-3-carboxamide] (JTE-907) and {N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2yl]5-(4-chloro-3-methyl-phenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide}} (SR144528). In contrast, JTE-907 did not affect arachidonic acid-induced swelling. Orally administered JTE-907 (0.1–10 mg/kg) and SR144528 (1 mg/kg) also produced significant inhibition of dinitrofluorobenzene-induced ear swelling, with increased cannabinoid CB₂ receptor mRNA expression observed in the inflamed ear. These results suggest that cannabinoid CB₂ receptor is partially involved in local inflammatory responses and cannabinoid CB₂ receptor antagonist/inverse agonist has beneficial effects on ear swelling.     

The antinociceptive effect of Delta9-tetrahydrocannabinol in the arthritic rat involves the CB(2) cannabinoid receptor

Cannabinoid CB₂ receptors have been implicated in antinociception in animal models of both acute and chronic pain. We evaluated the role both cannabinoid CB₁ and CB₂ receptors in mechanonociception in non-arthritic and arthritic rats. The antinociceptive effect of Δ⁹-tetrahydrocannabinol (Δ⁹THC) was determined in rats following administration of the cannabinoid CB₁ receptor-selective antagonist, SR141716A, the cannabinoid CB₂ receptor-selective antagonist, SR144528, or vehicle. Male Sprague–Dawley rats were rendered arthritic using Freund’s complete adjuvant and tested for mechanical hyperalgesia in the paw-pressure test. Arthritic rats had a baseline paw-pressure of 83 ± 3.6g versus a paw-pressure of 177 ± 6.42g in non-arthritic rats. SR144528 or SR141716A (various doses mg/kg; i.p.) or 1:1:18 (ethanol:emulphor:saline) vehicle were injected 1 h prior to Δ⁹THC (4mg/kg; i.p) or 1:1:18 vehicle and antinociception determined 30min post Δ⁹THC. AD₅₀'s for both antagonists were calculated with 95% confidence limits. In addition, midbrain and spinal cord were removed for determination of cannabinoid CB₁ and CB₂ receptor protein density in the rats. SR144528 significantly attenuated the antinociceptive effect of Δ⁹THC in the arthritic rats [AD₅₀ = 3.3 (2.7–4) mg/kg], but not in the non-arthritic rats at a dose of 10/mg/kg. SR141716A significantly attenuated Δ⁹THC-induced antinociception in both the non-arthritic [AD₅₀ = 1.4 (0.8–2) mg/kg] and arthritic rat [AD₅₀ = 2.6 (1.8–3.1) mg/kg]. SR141716A or SR144528 alone did not result in a hyperalgesic effect as compared to vehicle. Our results indicate that the cannabinoid CB₂ receptor plays a critical role in cannabinoid-mediated antinociception, particularly in models of chronic inflammatory pain.     

Intravenous self-administration of the cannabinoid CB1 receptor agonist WIN 55,212-2 in rats

RATIONALE: Delta9-tetrahydrocannabinol (Delta9-THC), the main psychoactive ingredient of marijuana, as well as synthetic cannabinoid (CB1) receptor agonists, has led to negative or equivocal results when tested with the intravenous self-administration procedure, the best validated behavioural model for evaluating abuse liability of drugs in experimental animals. We recently reported, however, that the synthetic CB1 receptor agonist WIN 55,212-2 is intravenously self-administered by drug-naive mice and that its self-administration is blocked by the cannabinoid CB1 receptor antagonist SR 141716A. OBJECTIVE: To assess a reliable model of cannabinoid intravenous self-administration in rats. Long Evans male rats were allowed the opportunity to self-administer WIN 55,212-2 at doses ranging from 6.25 to 50 microg/kg per injection, under a fixed-ratio 1 (FR1) schedule of reinforcement and nose-pokes as the operant responses. The effect of either a change in the unit drug dose available or a pretreatment with the specific CB1 receptor antagonist SR 141716A were then investigated (maintenance phase). Finally, the extinction of the self-administration behaviour was evaluated. RESULTS: Response rate depended on the drug dose available, with maximum rates occurring at 12.5 microg/kg per injection. Response rate increased following pretreatment with the specific CB1 receptor antagonist, SR 141716A. Moreover, operant behaviour rapidly extinguished following both the substitution of saline or vehicle for cannabinoid and the disconnection of the drug delivery pumps. CONCLUSION: Rats will intravenously self-administer the synthetic CB1 receptor agonist WIN 55,212-2 under specific experimental conditions, thus allowing further investigation of the neurobiological mechanisms underlying cannabinoid-taking behaviour.     

Influence of uridine-5-monophosphate on 3H-leucine incorporation into hippocampal neurons during learning

The influence of UMP (injected intraventricularly) on the incorporation of ³H-leucine (injected intraperitoneally) was studied in rats using the microautoradiographic technique. Under the conditions of a brightness discrimination, the incorporation of labeled leucine into hippocampal neurons was significantly increased by UMP pretreatment, whereas under control conditions UMP caused only a tendency of increase without any statistical significance. It is suggested, that under learning conditions UMP substitution increases RNA synthesis, which would yield an enhanced protein synthesis.     

亚低温对沙土鼠海马CA1区缺血后细胞凋亡的影响

目的 探讨亚低温对沙土鼠短暂性脑缺血后海马CA1区细胞凋亡的影响。方法 阻断沙土鼠双侧颈总动脉15分钟造成前脑缺血模型。实验动物随机分为假手术组、缺血再灌注组、亚低温治疗组。用光镜观察海马CA1区的神经元死亡过程．采用原位末端标记(TUNEL)法检测凋亡的神经元。结果 脑缺血后．海马CA1区锥体神经元于再灌注后2～7天死亡,再灌注第3天神经元开始凋亡．第5天达高峰。亚低温治疗抑制了缺血后海马CA1区神经元的死亡及细胞凋亡。结论 亚低温治疗对脑缺血后的神经元具有保护作用．并可抑制神经细胞凋亡的发生。     

Delta 9-tetrahydrocannabinol antagonizes endocannabinoid modulation of synaptic transmission between hippocampal neurons in culture

Cannabinoids inhibit excitatory synaptic transmission between hippocampal neurons in culture. Delta9-tetrahydrocannabinol (THC), the principal psychoactive component in marijuana, acts as a partial agonist at these synapses. Thus, THC inhibited but did not block synaptic transmission when applied alone and, when applied in combination with WIN552212-2, it partially reversed the effects of this full agonist. Here, we address the question of how THC might interact with endocannabinoid signaling. Reducing the extracellular Mg2+ concentration to 0.1 mM elicited a repetitive pattern of glutamatergic synaptic activity that produced intracellular Ca2+ concentration spikes that were measured by indo-1-based microfluorimetry. The endocannabinoid, 2-arachidonyl glycerol (2-AG) produced a concentration-dependent and complete inhibition of spike frequency with an EC50 of 63 +/- 13 nM. 2-AG (1 microM) inhibition of spiking was blocked by SR141716A (1 microM). THC (100 nM) antagonized the actions of 2-AG producing a parallel shift in the concentration-response relationship for 2-AG (EC50 of 1430 +/- 254 nM). The attenuation of 2-AG (1 microM) inhibition of synaptic activity by THC was concentration-dependent with an IC50 of 42 +/- 9 nM. These results demonstrate that THC can antagonize endocannabinoid signaling. Thus, the effects of THC on synaptic transmission are predicted to depend on the level of endocannabinoid tone.     

Delta(9)-Tetrahydrocannabinol-induced desensitization of cannabinoid-mediated inhibition of synaptic transmission between hippocampal neurons in culture

Prolonged exposure to cannabinoids results in desensitization of cannabinoid receptors. Here, we compared the desensitization produced by the partial agonist, Δ⁹-tetrahydrocannabinol (THC) to that produced by the full agonist Win55,212-2 on cannabinoid-mediated inhibition of glutamatergic synaptic transmission. Synaptic activity between rat hippocampal neurons was determined from network-driven increases in the intracellular Ca²⁺ concentration ([Ca²⁺]_i spikes). To assess the effects of prolonged treatment, cultures were incubated with cannabinoids, washed in 0.5% fatty-acid-free bovine serum albumin to ensure the removal of the lipophilic drug and then tested for inhibition of [Ca²⁺]_i spiking by Win55,212-2. In control experiments, 0.1 μM Win55,212-2 inhibited [Ca²⁺]_i spiking by 93 ± 5%. Win55,212-2 produced significantly less inhibition of [Ca²⁺]_i spiking following 18–24 h treatment with 1 μM THC (48 ± 5%) or treatment with 1 μM Win55,212-2 (29 ± 6%). Thus, THC produced significantly less functional desensitization than Win55,212-2. The desensitization produced by THC was maximal at 0.3 μM, remained stable between 1 and 7 days of preincubation and shifted the EC₅₀ of acute inhibition by Win55,212-2 from 27 to 251 nM. Differences in the long-term effects of cannabinoid receptor agonists on synaptic transmission may prove important for evaluating their therapeutic and abuse potential.