Morris水迷宫训练后丘脑前核胞外信号调节蛋白激酶表达的变化

目的探讨在空间记忆中丘脑前核细胞内信号转导是否与MAPK途径有关。方法成年雄性SD大鼠34只,分为3组:①PD组:侧脑室内注射PD098059溶液;②PD对照组;③正常组。在Morris水迷宫中,定位航行训练后,行侧脑室内注射,24h后空间探索实验。免疫组化和Western-Blot检测p-ERK的变化。结果在空间探索实验中PD组寻找平台次数及在靶象限停留时间与PD对照组及正常对照组相比明显减少(p<0.01)。在p-ERK免疫组化和Western-Blot中,PD组与PD对照组比较,丘脑前核内p-ERK表达明显减弱,光密度分析有显著性差异(p<0.01)。在PD对照组,丘脑前背侧核与丘脑前腹侧核相比,p-ERK表达显著增强,光密度分析有显著性差异(p<0.05)。结论丘脑前核空间记忆细胞内信号转导可能与MAPK途经有关。     

青、老年大鼠在Morris水迷宫中的学习记忆行为

本实验观察了22～24月龄老年大鼠和5～6月龄青年大鼠在Morris水迷宫中的学习记忆行为,并用定量分析方法比较两组动物在定位航行及空间搜索试验中的学习记忆,结果表明老年大鼠的寻找平台潜伏期明显延长,而其跨平台次数及在平台象限的游泳路线长度并未减少.提示24月龄老年大鼠获取学习记忆的能力受损伤而保持记忆的能力维持正常,这可能与二种功能衰老的不同速度及不同神经基础有关.     

青,老年大鼠在Morris水迷宫中的学习记忆行为

本实验观察了２２￣２４月龄老年大鼠和５￣６月龄青年大鼠在Ｍｏｒｒｉｓ水迷宫中的学习记忆行为，并用定量分析方法比较两组动物在定位航行及空间搜索试验中的学习记忆，结果表明老年大鼠的寻找平台潜伏期明显延长，而其跨平台次数及在平台象限的游泳路线长度并未减少。提示２４月龄老年大鼠获取学习记忆的能力受损伤而保持记忆的能力维持正常，这可能与二种功能衰老的不同速度及不同神经基础有关。     

重复Morris水迷宫训练提高大鼠空间学习能力却不影响空间记忆能力

采用每周一个周期的Morris水迷宫(MWM)训练(包括第1d的定位航行实验和第2d的空间探索实验),探讨重复MWM训练对大鼠空间学习、记忆能力的影响。在定位航行实验中,动物随机从不同象限连续入水5次以寻找隐藏站台,测量其上台潜伏期来评定其空间学习能力;在第二个训练日中,空间探索实验时撤去隐藏在靶象限的站台,计算大鼠在靶象限活动时间的百分比,评定大鼠的空间记忆能力。采用雄性SD大鼠20只,连续四周重复给予MWM定位航行和探索训练,分别评定大鼠空间学习和记忆能力。结果显示:随着训练次数的增加,动物的上台潜伏期逐渐缩短。同时,第一次的MWM训练能够提高大鼠的空间记忆能力,然而重复训练则轻微提高大鼠的空间记忆能力,但无统计学差异:在1、2、3、4周测得的靶象限内活动时间百分比分别为39.29%±1.62%,39.97%±2.34%,42.05%±2.32%,39.30%±1.64%。本实验结果提示:重复MWM定位航行能够增强动物的空间学习能力,但不影响动物的空间记忆能力。空间学习和记忆能力可能存在不同的形成机制。     

5-HT及其2A受体在大鼠丘脑前核的表达

目的研究5-羟色胺(5-HT)及其5-羟色胺2A受体(5-HT2AR)在大鼠丘脑前核的表达,探讨两者参与学习记忆的形态学依据。方法免疫组织化学ABC法观察5-HT及5-HT2AR在丘脑前核内的表达情况。包埋前免疫电镜技术观察丘脑前核群的5-HT能投射纤维终末。结果免疫组化结果显示:在大鼠丘脑前核群的前、中、后部均可见阳性的5-HT能神经元及大量串珠状的投射纤维终末,其中背侧核(AD)的神经元着色较深,胞体较大,纤维密集,平均光密度值(A值)与腹侧核(AV)的比较差异显著(P0.05);5-HT阳性反应产物主要定位于胞浆内,胞核不着色。包埋前免疫电镜显示:阳性5-HT能轴突终末与树突形成非对称性的轴-树突触。在AD、AV内可见黄色的5-HT2AR阳性神经元,其中AD的神经元胞体较大,着色较AV深,阳性产物灰度值二者比较差异显著(P0.05);阳性产物主要定位于神经元胞膜,胞核不着色。结论 5-HT和5-HT2AR在大鼠丘脑前核表达,在AD、AV的表达强度不同。     

学习记忆过程中p-CREB在大鼠丘脑前核内的表达

目的探讨在学习记忆过程中磷酸化的环磷酸腺苷反应元件结合蛋白(cAMP response element binding protein,CREB)在大鼠丘脑前核的表达情况,以进一步阐明磷酸化的CREB(p-CREB)与学习记忆的关系。方法选择形态相近成年雄性Wistar大鼠20只,简单随机法分为实验组(水迷宫训练)与对照组(游泳),每组10只。大鼠训练完毕后2 h内直接灌注取脑,免疫组织化学分析大鼠丘脑前核组织内p-CREB含量变化,观察不同丘脑前核部位实验组与对照组染色有无差别。结果水迷宫训练后实验组大鼠丘脑前核组织内即有明显的p-CREB阳性表达,而对照组均无明显p-CREB阳性表达(0.05)。实验组丘脑前背侧核与丘脑前腹侧核比较,两者间p-CREB阳性表达无明显差异(0.05)。结论丘脑前核内p-CREB可能参与学习记忆的信号转导过程。     

N-甲基-D-天冬氨酸受体在大鼠丘脑前核和扣带后回的表达

目的探讨大鼠丘脑前核和扣带后回内N-甲基-D-天冬氨酸受体NMDAR2A,NMDAR2B及NMDAR1(NR2A.NR2B及NR1)mRNA的表达,从形态学角度为系统研究丘脑前核的功能提供了依据。方法应用原位杂交方法检测丘脑前核及扣带后回内NR2A,NR2B以及NR1 mRNA的表达。结果原位杂交阳性反应产物为棕黄色,主要分布在神经元核周围胞浆中,胞核基本不着色。在丘脑前核,阳性神经元分布较密集,细胞形态较一致。扣带后回皮质阳性神经元在在大脑皮质不同部位分布有差异,分子层染色最弱,外颗粒层密集分布且染色增强,余四层较外颗粒层松散,染色细胞减少。结论 NR2A,NR2B以及NR1广泛分布在丘脑前核和扣带后回。     

穹窿海马伞切断鼠脑突触素动态变化及Morris水迷宫重复训练对其影响

目的在Morris水迷宫(MWM)重复训练的过程中观察穹窿海马伞切断大鼠的突触素(SYN)动态变化探讨阿尔茨海默病(AD)的发病机制和MWM重复训练学习和记忆能力对AD的影响,为临床应用提供实验依据。方法采用wistar大鼠60只,随机分为对照组、模型组和实验组,建模后连续四周给予Morris水迷宫重复训练定位航行和探索训练,分别评定大鼠空间学习和记忆能力,后进行海马突触素(SYN)免疫组化染色和超微电镜观察并进行统计学处理。结果随着训练次数的增加,对照组、模型组、实验组逃逸时间均逐渐缩短,实验组短于模型组,长于对照组(P0.05),提示空间学习能力得到提高。对照组、模型组和实验组大鼠在靶象限活动时间(s)百分比无明显差异(P0.05),提示空间记忆能力无明显提高。SYN免疫组化实验组SYN表达高于模型组,弱于对照组。结论MWM重复训练增加海马SYN表达可能与提高穹窿海马伞切断大鼠空间学习能力有关。     

基于小鼠Morris水迷宫和Y迷宫联合试验的多任务行为学测试研究

目的:通过观察小鼠Morris水迷宫和Y迷宫多任务联合试验与单独水迷宫或Y迷宫试验的结果差异,探讨两种记忆相关行为学试验之间是否存在相互干扰。方法:30只成年昆明小鼠随机分为单独水迷宫、单独Y迷宫和水迷宫+Y迷宫(简称联合组)三组。水迷宫试验记录小鼠寻找水下平台的逃避潜伏期、逃避距离、撤除平台后在目标象限内游泳时间和距离占全部时间与距离的百分比;Y迷宫试验记录小鼠在光-电刺激下逃往安全区的错误次数。结果:联合组与单独水迷宫组相比,小鼠逃避潜伏期、逃避距离以及目标象限内游泳所占的时间和距离百分比均无明显差异(P>0.05);联合组与单独Y迷宫组相比,第1和第2 d两组小鼠到达安全区的错误次数无明显差异,第3和第4 d联合组较单独组错误次数明显减少(P<0.05)。结论:两种行为学联合序贯试验对小鼠水迷宫空间学习记忆及第1至2 d Y迷宫工作记忆均不产生干扰;超过2 d的联合实验有助于增强小鼠Y迷宫工作记忆。因此,本研究为联合开展小鼠空间记忆和工作记忆研究提供了实验依据,提示合理地联合不同行为学实验将有助于提高实验效率、降低实验成本。     

Morris水迷宫实验中海马相关空间学习记忆的研究进展

空间学习与记忆是脑的高级神经生理活动之一,牵涉多个脑区、多种神经递质和细胞内信号分子,是一项十分复杂的神经生理活动过程。Morris水迷宫是1984年由英国生理学家Morris发明并被用于学习记忆脑机制研究,是用于啮齿类动物空间学习记忆的重要评估工具。海马是大脑的一个重要结构,海马的完整性对于空间学习来说至关重要。Morris水迷宫作为一种检测手段对大鼠海马损伤后效应特别敏感。在Morris水迷宫空间学习方面,海马结构具有特殊性和重要性。海马突触的可塑性和长时程增强效应是空间学习和记忆的神经功能基础。     

大鼠丘脑前核神经元内γ-氨基丁酸及其受体的表达

目的:探讨大鼠丘脑前核内γ-氨基丁酸(GABA)及其GABAA受体(GABAARα1和β2subunits)的表达,从形态学角度为系统研究丘脑前核的功能提供依据。方法:分别采用包埋后胶体金免疫电镜技术和原位杂交检测丘脑前核内GABA及GABAARα1和β2mRNA的表达。结果:(1)在丘脑前核,GABAARα1和GABAARβ2阳性神经元分布较密集,细胞形态较一致。空白对照切片为阴性,未见GABAARα1和GABAARβ2mRNA表达阳性神经元。(2)GABA胶体金免疫反应切片上,GABA胶体金颗粒浓重标记GrayⅡ型轴突终末,而树突、神经元、胶质细胞及背景标记极少。GABA能阳性轴突终末与中小型树突形成对称性轴-树突触,也与神经元胞体形成对称性轴-体突触。结论:提示在丘脑前核能够合成GABAARα1和GABAARβ2,且GABA能轴突终末与神经元的树突或胞体形成对称性突触。     

Nicotine improves AF64A-induced spatial memory deficits in Morris water maze in rats

Ethylcholine mustard aziridinium ion (AF64A) is a neurotoxic derivative of choline that produces not only long-term presynaptic cholinergic deficits, but also various memory deficits in rats similar to some characteristics observed in Alzheimer's disease patients. This study investigated whether nicotine (NCT) administration attenuated spatial learning deficits induced by intracerebroventricular AF64A treatment. AF64A (6 nmol/6 μl)-or saline (SAL)-treated rats were trained in Morris water maze task. NCT (0.025–0.25 mg/kg) was subcutaneously injected 5 min before the training every day. The results showed that moderate dose (0.10 mg/kg) of NCT attenuated AF64A-induced prolongation of escape latency. Furthermore, NCT dose-dependently recovered the AF64A-induced decrease of time spent in the target quadrant in the probe test. These results suggest that NCT improves AF64A-induced spatial memory deficits, and thus it is a potential therapeutic agent for the treatment of memory deficits in dementia.     

Tolerance development to Morris water maze test impairments induced by acute allopregnanolone

The progesterone metabolite allopregnanolone, like benzodiazepines, reduces learning and impairs memory in rats. Both substances act as GABA agonists at the GABA-A receptor and impair the performance in the Morris water maze test. Women are during the menstrual cycle, pregnancy, and during hormone replacement therapy exposed to allopregnanolone or allopregnanolone-like substances for extended periods. Long-term benzodiazepine treatment can cause tolerance against benzodiazepine-induced learning impairments. In this study we evaluated whether a corresponding allopregnanolone tolerance develops in rats. Adult male Wistar rats were pretreated for 3 days with i.v. allopregnanolone injections (2 mg/kg) one or two times a day, or for 7 days with allopregnanolone injections 20 mg/kg intraperitoneally, twice a day. Thereafter the rats were tested in the Morris water maze for 5 days and compared with relevant controls. Rats pretreated with allopregnanolone twice a day had decreased escape latency, path length and thigmotaxis compared with the acute allopregnanolone group that was pretreated with vehicle. Pretreatment for 7 days resulted in learning of the platform position. However, the memory of the platform position was in these tolerant rats not as strong as in controls only given vehicle. Allopregnanolone treatment was therefore seen to induce a partial tolerance against acute allopregnanolone effects in the Morris water maze.     

Ontogenetic differences in retention of spatial learning tested with Morris water maze

Two experiments examined retention of spatial learning in rats using a Morris water maze. Retention was scored in terms of probe trial performance when the platform was removed. Latency to reach the platform location, percent of time in the quadrant that had contained the platform, and relative frequency of visits to the platform location were analyzed. Results of the first experiment showed that preweanlings and juveniles exhibited substantial forgetting at 3- and 7-day retention intervals. Forgetting in adults was much lower than that found in the younger animals, and no differences in amount of forgetting appeared between the 3- and 7-day retention intervals at any age. The second experiment showed that forgetting in juveniles was alleviated by a single training trial administered just prior to the probe trial. These results are discussed in terms of ontogenetic differences in memory processing and measurement issues pertinent to the Morris water maze test procedure. © 1997 John Wiley & Sons, Inc. Dev Psychobiol 30: 329–341, 1997     

应用水迷宫测试糖尿病大鼠空间记忆能力变化的研究

目的 研究大鼠患糖尿病后,空间记忆能力和空间关联记忆能力受到的影响.方法 将70只SD大鼠（体质量180 g±20 g）随机分成3组,对照组、1型糖尿病组和2型糖尿病组.采用STZ一次性腹腔注射和联合高脂饲料喂养的方法分别制备1型和2型糖尿病大鼠模型,检测血糖水平.在造模成功的1个月和3个月后,分别进行水迷宫实验,包括4 d的定位航行和1 d的空间探索实验.结果 在糖尿病造模成功的1个月后,大鼠没有发生明显的空间记忆能力或空间关联记忆能力障碍.造模3个月后,在定位航行实验中,2组糖尿病大鼠的逃避潜伏期都比对照组时间长,具有统计学差异（P＜0.05）.实验第2天开始,对照组逃避潜伏期的下降趋势明显,而糖尿病组下降缓慢.1型和2型糖尿病组之间的逃避潜伏期没有显著差异（P＞0.05）.造模3个月后,在空间探索实验中,从训练过的Ⅰ象限入水时,2个糖尿病模型组平台象限游泳时间短,第1环点数和总得分等参数低,与对照组的差异都具有显著意义（P＜0.05）,2型糖尿病组的参数值比1型糖尿病组稍低.从未训练的Ⅳ象限入水时,糖尿病模型组的参数值也均低于正常对照组,具有统计学差异（P＜0.05）,且1型糖尿病组的总得分比2型糖尿病组更低一些.结论 1型或2型的糖尿病大鼠会发生空间记忆能力和空间关联记忆能力的下降.本实验中2型糖尿病组的空间记忆能力比1型糖尿病组受到了更明显的影响,而1型糖尿病组的空间关联记忆能力受到的影响比2型糖尿病组更大.     

Intracranial self-stimulation facilitates a spatial learning and memory task in the Morris water maze

Learning and memory improvement by post-training intracranial self-stimulation has been observed mostly in implicit tasks, such as active avoidance, which are acquired with multiple trials and originate rigid behavioral responses, in rats. Here we wanted to know whether post-training self-stimulation is also able to facilitate a spatial task which requires a flexible behavioral response in the Morris water maze. Three experiments were run with Wistar rats. In each of them subjects were given at least five acquisition sessions, one daily, consisting of 2-min trials. Starting from a random variable position, rats had to swim in a pool until they located a hidden platform with a cue located on its opposite site. Each daily session was followed by an immediate treatment of intracranial self-stimulation. Control subjects did not receive the self-stimulation treatment but were instead placed in the self-stimulation box for 45 min after each training session. In the three successive experiments, independent groups of rats were given five, three and one trial per session, respectively. Temporal latencies and trajectories to locate the platform were measured for each subject. Three days after the last acquisition session, the animals were placed again in the pool for 60 s but without the platform and the time spent in each quadrant and the swim trajectories were registered for each subject. A strong and consistent improvement of performance was observed in the self-stimulated rats when they were given only one trial per session, i.e. when learning was more difficult. These findings agree with our previous data showing the capacity of post-training self-stimulation to improve memory especially in rats with little training or low conditioning levels, and clearly prove that post-training self-stimulation can also improve spatial learning and memory.