戊四氮点燃癫癎大鼠空间学习记忆改变及海马NR2B表达

目的观察戊四氮点燃癫癎大鼠空间学习记忆功能变化及海马NMDA2型受体(NR2)B亚单位(NR2B)表达,探讨二者的关系及PTZ致癎大鼠认知障碍发生的分子机制。方法采用戊四氮(PTZ)慢性癫癎(CE)模型,Y-迷宫对两组大鼠进行行为学检测,免疫组织化学方法观察两组大鼠海马CA3区NR2B表达的变化,反转录多聚酶链反应(RT-PCR)方法检测大鼠海马NR2B mRNA的表达。结果癫癎组大鼠空间学习记忆能力受损;其海马CA3区NR2B阳性细胞较对照组明显减少(P<0.01),同时伴有海马NR2B mRNA表达下降(P<0.01)。结论戊四氮点燃癫癎大鼠空间学习记忆受损可能与海马神经元NR2B的表达减少有关。     

低剂量伽玛刀照射对癫痫大鼠皮层及海马NMDA受体亚基表达的影响

目的观察低剂量伽玛刀照射对癫痫大鼠皮层和海马N-甲基-D-天氡氨酸(N-methyl-Daspartate,NMDA)受体亚基表达的影响。方法根据动物是否致痫及接受伽玛刀照射,将大鼠分为4组:对照组、伽玛刀组、药物致痫组、伽玛刀+药物组。腹腔连续注射戊四氮(pentylenetetrazole,PTZ)制备癫痫大鼠模型,以双侧额叶为照射靶区对大鼠进行低剂量伽玛刀照射,边缘剂量为15Gy。观察并记录各组大鼠伽玛刀照射前、后癫痫发作情况,并于伽玛刀照射后12周后留取脑组织,分别利用免疫组化及免疫蛋白印迹法对大鼠皮层及海马NMDA受体亚基NR1、NR2A和NR2B进行检测。结果对照组及伽玛刀组大鼠无痫性发作表现,与药物致痫组大鼠相比,伽玛刀+药物组大鼠经低剂量伽玛刀照射后12周,痫性发作明显减轻(P0.05)。与对照组相比,药物致痫组大鼠额叶皮层及海马CA1、CA3区NR1、NR2A和NR2B表达均明显增强(P0.05),阳性神经元数目及平均吸光度值均明显增加(P0.05);与药物致痫组比较,伽玛刀+药物组额叶皮层及海马CA1、CA3区NR1、NR2A和NR2B表达均明显降低(P0.05),阳性神经元数目及平均吸光度值明显减少(P0.05);伽玛刀组与对照组无明显差别(P0.05)。结论癫痫大鼠额叶皮层及海马NR1、NR2A及NR2B亚单位蛋白表达增强,低剂量伽玛刀照射可能引起癫痫大鼠皮层及海马NMDA受体亚基表达减少,这可能是低剂量伽玛刀抑制癫痫发作的分子机制之一。     

局灶性皮质发育不良皮质中NMDA受体亚基表达情况

目的探讨N-甲基-D-天冬氨酸(N-methyl-D-aspartate,NMDA)受体亚基NR1、NR2A、NR2B在难治性癫病人局灶性皮质发育不良(focal cortical dysplasia,FCD)皮质中的表达及意义。方法选取20例难治性颞叶癫(术后病理证实为FCD)为FCD组及10例颞叶血管畸形病人为对照组,收集两组病人术中切除的颞叶皮质,利用免疫组化和Syber Green荧光定量PCR技术检测标本中NMDA受体亚基NR1、NR2A、NR2B蛋白和mRNA的表达情况。结果对照组NR1、NR2A和NR2B蛋白表达分别为3.5、3、3,FCD组分别为5、5、5。对照组NR1、NR2A和NR2B mRNA表达分别为1.109、1.079、1.157,FCD组分别为2.176、2.324、2.348。与对照组比较,FCD组NR1、NR2A、NR2B蛋白和mRNA表达显著增加(均P<0.01)。结论 FCD皮质中NMDA受体亚基蛋白及mRNA表达升高,可能是FCD致机制之一。     

盐酸多奈哌齐对拟VaD大鼠海马CA1区NR1及NR2B免疫组织化学表达的影响

目的探讨盐酸多奈哌齐对拟血管性痴呆大鼠海马神经元N-甲基-D-天门冬氨酸(NMDA)受体亚单位R1(NMDAR1,NR1)和R2B(NMDAR2B,NR2B)的免疫组织化学表达的影响。方法采用双侧颈总动脉反复夹闭、再通,并腹腔注射硝普钠法制备模型,用盐酸多奈哌齐溶液灌胃,Y-型迷宫试验观察其行为学改变,用免疫组织化学技术观测大鼠海马神经元NR1、NR2B的表达变化。结果盐酸多奈哌齐组大鼠海马CA1区NR1表达明显降低,与模型组比较有显著性差异(均P<0.01),与假手术组相比差异无显著性;NR2B表达较模型组明显增高(P<0.01),与假手术组比较无显著性差异。结论盐酸多奈哌齐有可能通过降低NR1的表达,提高海马NR2B的表达,从而改善拟血管性痴呆大鼠的学习、记忆成绩。     

血管性痴呆大鼠N-甲基-D-天冬氨酸-2B受体变化机制的研究

目的 研究血管性痴呆（VD）大鼠形成过程中N-甲基D-天冬氨酸-2B受体（NR2B）的变化规律及作用机制.方法 永久性结扎双侧颈总动脉制备VD大鼠模型,用Morris水迷宫衡量大鼠的学习记忆水平,用免疫组化法检测大鼠海马NR2B的表达.结果 随缺血时间延长,VD大鼠的学习记忆能力下降,缺血4周后与对照有显著差异（P＜0.01）;NR2B的表达随缺血时间变化,呈先升后降改变,缺血2周时表达最多,与对照有显著差异（P＜0.01）,此后逐渐减少,并明显低于对照组（P＜0.01）,缺血16周时表达最少.结论 VD大鼠学习记忆的改变与海马NR2B的变化相关,缺血早期NR2B过表达产生神经毒引起该能力下降;而在慢性缺血期,这种损害则是因NR2B含量不足难以完成生理功能所致.     

神经生长因子对脑缺血大鼠学习与记忆的影响

目的为了观察神经生长因子（NGF）对脑缺血大鼠学习与记忆的影响和海马内N-甲基-D-天门冬氨酸受体NR2A/B亚zhanghaopeng（NR2A/B）表达的变化。方法本研究将48只成年雄性SD大鼠分为正常组（n=12）、假手术组（n=12）、慢性脑缺血组（n=12）、NGF处理组（n=12）。于造模后开始腹腔注射0.25 ug/100 g NGF,假手术组和慢性脑缺血组腹腔注射等量生理盐水,均1次/d,共21 d。用Morris水迷宫和＂＂Y＂迷宫作业测试其空间学习与记忆成绩,再采用Western blot方法分析海马的NR2A、NR2B的表达。结果①Morris水迷宫测试：模型组大鼠寻找平台的潜伏期较假手术组明显延长,NGF处理组大鼠寻找平台的潜伏期较模型组明显缩短;＂Y＂迷宫测试：模型组大鼠学会躲避电击的正确次数较假手术组明显减少,NGF处理组大鼠学会躲避电击的正确次数较模型组明显增多;②模型组NR2A表达水平较假手术组明显降低,而NR2B明显升高;NGF处理组海马内NR2A表达水平较模型组明显上调,而NR2B明显下调。结论神经生长因子可增强学习与记忆,海马内N-甲基-D-天门冬氨酸（NMDA）受体表达变化可能是影响学习与记忆的机制之一。     

轻型颅脑损伤对大鼠脑源性神经营养因子基因表达的影响及意义

目的探讨轻型颅脑损伤对大鼠脑源性神经营养因子(BDNF)基因表达的影响及意义.方法120只成年SD大鼠根据性别不同分为雌性对照组、雌性实验组、雄性对照组和雄性实验组,每组30只.两实验组建立侧位液压冲击轻型颅脑损伤模型.Morris水迷宫试验测试大鼠学习记忆能力,RT-PCR检测海马中BDNF mRNA的表达.结果水迷宫定位航行试验第4天,同性别大鼠实验组平均逃逸潜伏期较对照组明显延长(P＜0.05);空间探索试验同性别大鼠实验组寻找平台潜伏期较对照组明显延长(P＜0.05),穿越平台次数较对照组减少(P＜0.05);同性别大鼠实验组大脑海马中BDNFmRNA的表达显著低于对照组(P＜0.01).结论侧位液压冲击轻型颅脑损伤会降低模型鼠大脑海马中BDNF mRNA的表达,并可能因此导致大鼠学习记忆能力下降.     

慢性铝暴露对大鼠海马神经元中toll样受体4蛋白及其mRNA表达的影响

目的 通过研究铝暴露对介导天然免疫的关键蛋白toll样受体(TLR)的影响,探讨慢性铝暴露诱导学习记忆损伤的潜在机制.方法 取80只断乳后Wistar大鼠,随机分为4组,每组20只;其中1组为对照组(用蒸馏水喂养),其他3组为铝暴露组,分别用含0.2%、0.4%和0.6%浓度的AlCl_3蒸馏水喂养3个月.免疫印迹(Western blot)方法检测各组大鼠海马中TLR4的蛋白表达情况;逆转录-聚合酶链反应(RT-PCR)方法检测各组大鼠海马中TLR4 mRNA的表达情况.结果 铝暴露组大鼠的学习记忆能力下降;与对照组(0.91±0.14)相比,0.2%、0.4%和0.6%浓度的铝暴露各组海马组织TLR4的蛋白表达(0.95±0.15、1.44±0.22、2.03±0.28)显著增高(F=37.575,P<0.05);与对照组(0.59±0.06)相比,铝暴露各组TLR4 mRNA的表达(0.86±0.04、0.95±0.04、1.06±0.09)显著增高(F=65.474,P<0.05).结论 慢性铝暴露损伤大鼠的学习记忆能力可能与上调TLR4蛋白及其mRNA的表达相关.     

咖啡因对慢性低O2高CO2大鼠学习记忆及N-甲基-D-天冬氨酸受体亚基1 mRNA表达的影响

目的：探讨咖啡因对慢性低O2高CO2处理的大鼠空间学习记忆、皮质和海马N-甲基-D-天冬氨酸受体（NMDAR）亚基1mRNA（NR1 mRNA）表达的影响。方法：SD大鼠48只分为4组,正常对照组;低O2高CO24周（HH）组,处理组：低O2高CO2＋咖啡因0．1mg·mL^-14周（HCl组）,低O2高CO2＋咖啡因0．3mg·mL^-14周（HC2组）。处理组以咖啡因水溶液干预4周后行Morris水迷宫实验,观察大鼠寻找站台的平均逃避潜伏期和游泳总距离;采用原位杂交法观察大鼠海马及皮质区NRImRNA的表达与分布情况。结果：①Morris水迷宫实验显示,HH组与对照组相比大鼠寻找站台的平均逃避潜伏期延长、游泳总距离增加（P〈0．05）,HC2组有显著性降低（P〈0．05）;②原位杂交显示NR1 mRNA阳性细胞广泛分布于海马和皮质区;模型组与对照组比较大鼠海马锥体细胞层NR1 mRNA表达的平均吸光度值降低（P〈0．05）,而咖啡因处理组平均吸光度值升高。结论：咖啡因可改善慢性低O2高CO2大鼠的空间学习记忆能力并增加海马和皮质区NR1 mRNA的表达。     

芬太尼、咪达唑仑复合麻对大鼠认知功能及海马NR1、NR2B表达的影响

目的 探讨芬太尼、咪达唑仑复合麻醉对大鼠认知功能及海马NR1、NR2B表达的影响.方法 雄性Wistar大鼠随机分为3组,即对照组、复合麻醉组、催醒组,每组6只.复合麻醉组和催醒组均腹腔注射芬太尼0.5mg/kg、咪达唑仑50mg/kg进行麻醉诱导,以翻正反射消失为标准记录大鼠麻醉起效时间.催醒组在麻醉起效30min后腹腔注射纳络酮0.5mg/kg、氟马西尼0.8mg/kg进行动物催醒,记录从给予拮抗剂到动物出现翻正反射的复苏时间.对照组腹腔注射等体积的生理盐水.各组大鼠于实验结束后7d内采用Y型电迷宫对大鼠进行认知功能测试,测试结束后处死动物,分离双侧海马,RT-PCR测定海马组织内NR1、NR2B的mRNA表达.结果 复合麻醉组大鼠Y迷宫实验正确反应率较对照组显著下降(P＜0.01),NR2B的mRNA表达显著降低(P＜0.01);催醒组大鼠正确反应率和NR2B的mRNA表达与对照组相比无显著差异,NR1的表达在各组差异不明显.结论 芬太尼、咪达唑仑复合麻醉可引起大鼠短期内一定的认知功能损害,其机制可能与NR2B基因表达下调有关.     

Long-term effects of seizures in neonatal rats on spatial learning ability and N-methyl-D-aspartate receptor expression in the brain

For the purpose of investigating the long-term effects of seizures in neonatal rats on spatial learning ability and N-methyl-D-aspartate (NMDA) receptor expression in adult rat brain, a seizure was induced by inhalant flurothyl daily in neonatal Wistar rats from postnatal day 6 (P6). The authors assigned six rats each averagely into the single-seizure group, the recurrent-seizure group (seizures induced in six consecutive days), and the control group. During P60 to P65, the rats were tested for spatial learning ability with the Morris water maze task. On P75, the authors examined protein expression of the NMDA receptor (NR) subunits, NR1, 2A, 2B, 2C, and 2D, in the cerebral cortex and hippocampus by Western blotting analysis. On P65, the escape latencies from the water maze of the rats in the recurrent-seizure group were significantly longer than those of the control rats, but there was no difference between the single-seizure group and the control group. NR subunit expression in the cerebral cortex and hippocampus of the rats with single seizure was similar to those in the control rats. Compared with the control rats, the protein expressions of NR1, NR2A and NR2B in the cerebral cortex and NR2A in the hippocampus of the recurrent-seizure group was significantly decreased, but NR2C protein expression in the cerebral cortex and hippocampus significantly increased. Recurrent seizures induced in neonatal rats might cause long-term spatial learning ability deficit and modify NR expression in the cerebral cortex and hippocampus of adult rats. The results suggest that abnormal NR expression might play an important role in long-term spatial learning ability deficit induced by recurrent seizures in early life.     

Developmental regulation and lateralization of N-methyl-d-aspartate (NMDA) receptors in the rat hippocampus

N-methyl-d-aspartate receptors (NMDARs) are expressed abundantly in the brain and play a crucial role in the regulation of central nervous system (CNS) development, learning, and memory. During early neuronal development, NMDARs modulate neurogenesis, neuronal differentiation and migration, and synaptogenesis. The present study aimed to examine the developmental expression of NMDARs subunits, NR1 and NR2B, in the developing hippocampus of neonatal rats during the first two postnatal weeks. Fifty-four male offspring were randomly divided into three age groups, postnatal days (P) 0, 7, and 14. Real-time-PCR, western blotting, and immunohistochemistry (IHC) analyses were employed to examine and compare the hippocampal expression of the NMDA receptor subunits. The highest mRNA expression of NR1 and NR2B subunits was observed at P7, regardless of its laterality. The mRNA expression of both subunits in the right hippocampus was significantly higher than that of the left one at P0 and P7. Similarly, the highest protein level expression of NR1 and NR2B subunits was also observed at P7 in both sides hippocampi. Although the protein expression of NR1 was significantly higher on the right side in all studied days, the NR2B was significantly higher in the right hippocampus only at P7. The analysis of optical density (OD) has shown a marked increase in the distribution pattern of the NR1 and NR2B subunits at P7 in all hippocampal subregions. In conclusion, there is a marked right-left asymmetry in the expression of NR1 and NR2B subunits in the developing rat hippocampus, which might be considered as a probable mechanism for the lateral differences in the structure and function of the hippocampus in rats.     

NMDAR-2A subunit protein expression is reduced in the hippocampus of rats exposed to Pb2+ during development

Chronic exposure to lead (Pb2+) produces deficits of learning and memory in children and spatial learning deficits in developing rats. The N-methyl-D-aspartate receptor (NMDAR) has been identified as a principal target for Pb2+-induced neurotoxicity. Age-dependent changes in NMDAR subunit gene expression were observed in hippocampi of rats chronically exposed to Pb2+ during development [T.R. Guilarte, J.L. McGlothan, Hippocampal NMDA receptor mRNA undergoes subunit specific changes during developmental lead exposure, Brain Res. 790 (1998) 98-107]. These changes were present at blood Pb2+ levels ranging from 20-60 microg/dl. Littermates were used in the present study to determine whether the changes in gene expression were reflected in protein levels. NR1, NR2A, and NR2B subunit protein levels were measured in rat hippocampus and cortex at post-natal days (PND) 7, 14, 21, and 28 by Western blot and densitometric analysis. A treatment effect was apparent for NR2A subunit protein expression in the hippocampus (F1,28=10.224, p<0.01). NR2A subunit protein was reduced by 40%, 19%, and 27% from control levels in PND14, 21, and 28 Pb2+-exposed rats, respectively. Mean comparisons indicated that rats at PND14 exhibited the most significant reduction of NR2A (p<0.001). These data concur with our previous finding of reduced NR2A mRNA found in hippocampal pyramidal and granule cells of Pb2+-exposed rats. Pb2+ exposure during development had no effect on NR1 or NR2B subunit protein expression in the hippocampus at any age. No effect was observed on any subunit in the cortex at any age. The developmental profile of the NMDAR-2A subunit protein in the hippocampus is specifically changed by chronic exposure to Pb2+. These data suggest that composition of subunits comprising NMDAR may be altered in Pb2+-exposed rats.     

Let-7c-1对戊四氮致痫大鼠学习记忆功能的作用

目的研究let-7c-1对戊四氮(pentylenetetrazol,PTZ)致痫大鼠学习记忆功能的影响,探讨其可能机制。方法通过PTZ腹腔注射SD雄性大鼠建立慢性癫痫模型,随机分为癫痫组、干预对照组、let-7c-1激动剂组,各组12只,另设12只大鼠为正常组。28 d后,观察各组大鼠的行为学变化,let-7c-1基因表达及大鼠海马组织中Bcl-2、Caspase3蛋白的表达。结果与正常组相比,癫痫组大鼠逃避潜伏期延长、穿越平台次数减少、在目标象限的总路程缩短,差异有统计学意义(P0.05);癫痫组与干预对照组相比,逃避潜伏期、穿越平台次数、在目标象限的总路程无统计学差异(P0.05);与干预对照组相比,let-7c-1激动剂组逃避潜伏期明显延长,穿越平台次数减少、在目标象限的总路程缩短,差异有统计学意义(P0.05)。干预对照组与let-7c-1激动剂组let-7c-1基因相对表达量分别为(1.35±0.32)、(62.53±21.01)(F=50.97,P0.05)。癫痫组let-7c-1基因表达量高于正常组,差异有统计学意义(P0.05)。let-7c-1激动剂组let-7c-1基因表达量明显高于干预对照组、癫痫组及正常组,差异有统计学意义(P0.05)。与正常组相比,癫痫组的Bcl-2蛋白表达减少,Caspase3蛋白表达增加,差异有统计学意义(P0.05);癫痫组与干预对照组相比,Bcl-2蛋白及Caspase3蛋白的表达无统计学差异(P0.05)。与干预对照组相比,let-7c-1激动剂组Bcl-2蛋白表达明显减少,Caspase3蛋白表达明显增加,差异有统计学意义(P0.05)。结论 Let-7c-1可能通过减少海马组织Bcl-2蛋白及增加Caspase-3蛋白表达使PTZ致痫大鼠的学习记忆功能受损。     

癫痫持续状态对发育期大鼠认知功能的影响及cAMP/PKA信号通路所起作用

目的 探讨癫痫持续状态(SE)对发育期大鼠认知功能的影响及环磷酸腺苷/蛋白激酶A(cAMP/PKA)信号转导通路在其中所起的作用.方法 SD大鼠32只按照完全随机数字表法分为SE组、生理盐水(NS)组,每组16只.戊四氮(PTZ)诱导大鼠SE,Morris水迷宫和Y迷宫实验观察大鼠学习记忆功能的改变,放射免疫分析法测定海马组织cAMP的含量,免疫组织化学方法检测海马各区PKA的表达.结果 SE组大鼠在Morris水迷宫中平均逃避潜伏期延长,原平台所在象限的游泳时间缩短,与NS组比较差异有统计学意义(P<0.05).在Y迷宫中达标所需的训练次数增多,24 h记忆保持率下降,与NS组比较差异有统计学意义(P<0.05).NS组大鼠海马cAMP的含量为(280.38±22.66)pmol/g,SE组为(147.25±16.83)pmol/g,差异有统计学意义(P<0.05).SE组CA3区和CA1区PKA的表达较NS组明显减少.结论 SE可以导致发育期大鼠认知功能障碍,其机制可能与cAMP/PKA信号转导通路的功能受损有关.

Abstract：

Objective To observe the influence of status epilepticus (SE) on cognitive function of immature rats and explore the role of hippocampal cAMP/PKA signaling pathway in cognitive function impairment of immature rats. Methods Immature male SD rats were assigned randomly to 2 groups: SE group, induced by intraperitoneal injection of pentylenetetrazole (PTZ, n=16), and normal saline control group (n=16). Learning and memory tests using the Morris water maze and Y-maze were performed 7 d after SE. After testing, alterations of content of cAMP were detected by radioimmunoassay,and the expression of PKA in the hippocampus was examined by immunohistochemistry. Results SE rats exhibited learning and memory deficits in the Morris water maze and Y-maze tests: as compared with those in the controls in Morris water maze, the mean escape latency of searching the platform obviously prolonged and the swimming time in the original platform region significantly shortened in SE rats (P<0.05); as compared with those in the controls in Y maze, the number of standard training times obviously increased and the rate of retention of memory significantly decreased in SE rats (P<0.05). At the same time, the cAMP content in hippocampus of SE rats ([147.25±16.83] pmol/g) was significantly lower as compared with that in controls ([280.38±22.66] pmol/g), and the expression of PKA in the CA3 and CA1 areas within hippocampal area of SE rats was obviously decreased as compared with that in controls (P<0.05). Conclusion SE could result in learning and memory deficits in immature rats, which may be related to the impairment of hippocampal cAMP/PKA signaling pathway.