吗啡精神依赖大鼠VTA-NAc-PFC神经环路谷氨酸含量和NR2B表达的变化

目的 观察吗啡诱导条件性位置偏爱大鼠中脑腹侧被盖区-伏核-前额叶皮质(VTA-NAc-PFC)神经环路各核团谷氨酸递质含量和N-甲基-D-天冬氨酸受体亚基NR2B表达的变化,从受体前和受体层面探讨该环路中通过谷氨酸能系统的阿片类精神依赖机制.方法 筛选出合格大鼠32只并按随机数字表法分为生理盐水对照组和吗啡条件性位置偏爱模型组(模型组),模型组采用吗啡剂量递增法建立大鼠条件性位置偏爱模型,分别用比色法和免疫组化染色检测中脑腹侧被盖区、伏核和前额叶皮质内谷氨酸含量和NR2B的表达.结果 与生理盐水对照组比较,模型组大鼠在白箱的停留时间明显延长,VTA-NAc-PFC神经环路各核团谷氨酸含量明显增高,NR2B平均吸光度值明显增加,差异均有统计学意义(P<0.05).结论 VTA-NAc-PFC神经环路谷氨酸递质含量及其受体亚基NR2B表达水平上调在吗啡精神依赖形成中发挥重要作用.     

吗啡精神依赖大鼠VTA-NAc-PFC神经环路谷氨酸含量和NR2B表达的变化

目的 观察吗啡诱导条件性位置偏爱大鼠中脑腹侧被盖区-伏核-前额叶皮质(VTA-NAc-PFC)神经环路各核团谷氨酸递质含量和N-甲基-D-天冬氨酸受体亚基NR2B表达的变化,从受体前和受体层面探讨该环路中通过谷氨酸能系统的阿片类精神依赖机制.方法 筛选出合格大鼠32只并按随机数字表法分为生理盐水对照组和吗啡条件性位置偏爱模型组(模型组),模型组采用吗啡剂量递增法建立大鼠条件性位置偏爱模型,分别用比色法和免疫组化染色检测中脑腹侧被盖区、伏核和前额叶皮质内谷氨酸含量和NR2B的表达.结果 与生理盐水对照组比较,模型组大鼠在白箱的停留时间明显延长,VTA-NAc-PFC神经环路各核团谷氨酸含量明显增高,NR2B平均吸光度值明显增加,差异均有统计学意义(P<0.05).结论 VTA-NAc-PFC神经环路谷氨酸递质含量及其受体亚基NR2B表达水平上调在吗啡精神依赖形成中发挥重要作用.

Abstract：

Objective To explore the mechanism of opioid-psychic dependence involving the aspects of pre-receptor and receptor by observing the changeable expressions of glutamate neurotransmitter and NR2B of N-methyl-D-aspartic acid (NMDA) receptor in the neuroanatomical circuit of ventral temental area, nucleus accumbens and prefrontal cortex (VTA-Nac-PFC) of rats subjected to morphine-induced conditioned place preference (CPP). Methods The models of CPP were validated by escalating doses of morphine in rats (n=16). The colorimetry and immunohistochemistry ways were applied to detect the contents of glutamic acid and the expression level of NR2B in VTA, Nac and PFC. Results As compared with those in the control group physiological saline), the prolonged detention time of white compartment in the model group was notably observed (P<0.05), and increased content of glutamic acid and expression level of NR2B in fields of VTA, Nac and PFC in the model group were significantly detected (P<0.05). Conclusion Increased level of giutamic acid and expression level of NR2B in nuroanatomieal circuit of VTA, Nac and PFC could play key roles in inducing morphine-psychic dependent rats.     

吗啡相关环境线索调节腹侧海马下托区谷氨酸和γ-氨基丁酸的释放

目的 研究吗啡相关环境线索能否调节腹侧海马下托区谷氨酸和γ-氨基丁酸的释放。方法 采用条件性位置偏爱和条件性位置厌恶模型分别建立与吗啡奖赏、厌恶相关的环境线索。采用微透析和高效液相荧光检测法测定上述环境线索下大鼠腹侧海马下托区细胞外谷氨酸和γ-氨基丁酸的浓度。结果 吗啡奖赏相关环境线索引起腹侧海马下托区细胞外γ-氨基丁酸浓度下降了约11％,吗啡厌恶相关的环境线索引起腹侧海马下托区细胞外的谷氨酸浓度增加了约230％。结论 吗啡相关的环境线索可能通过不同的神经环路调节腹侧海马下托区神经递质的释放。     

吗啡相关环境线索调节腹侧海马下托区谷氨酸和γ-氨基丁酸的释放(英文)

目的研究吗啡相关环境线索能否调节腹侧海马下托区谷氨酸和γ-氨基丁酸的释放。方法采用条件性位置偏爱和条件性位置厌恶模型分别建立与吗啡奖赏、厌恶相关的环境线索。采用微透析和高效液相荧光检测法测定上述环境线索下大鼠腹侧海马下托区细胞外谷氨酸和γ-氨基丁酸的浓度。结果吗啡奖赏相关环境线索引起腹侧海马下托区细胞外γ-氨基丁酸浓度下降了约11%,吗啡厌恶相关的环境线索引起腹侧海马下托区细胞外的谷氨酸浓度增加了约230%。结论吗啡相关的环境线索可能通过不同的神经环路调节腹侧海马下托区神经递质的释放。     

神经厌食症大鼠NAc-PFC-VTA环路中5-HT表达的变化

目的研究神经厌食症大鼠模型伏隔核-前额叶皮质-中脑腹侧被盖区(NAc-PFC-VTA)神经环路中各核团5-HT表达的变化。方法 12只大鼠随机分为正常喂养组和运动诱发的神经厌食症大鼠模型组,模型组采用24小时不限制接触转轮运动及严格限制喂食(1h/日),当体重低于正常喂养组25%时提示造模成功,确认造模成功后灌注取脑,利用免疫荧光染色观察NAc,PFC和VTA核团中5-HT表达的情况。结果模型组大鼠不限制接触转轮6～8天体重低于正常喂养组25%。免疫荧光染色显示神经厌食症大鼠NAc,PFC和VTA核团内的5-HT表达较正常喂养组显著降低(P0.05)。结论神经厌食症大鼠NAc,PFC和VTA核团中5-HT的表达均降低。     

电刺激伏核对吗啡成瘾心理依赖大鼠行为学的影响

目的 通过建立脑深部刺激(deep brain stimulation,DBS)SD大鼠双侧伏核的动物模型,探讨DBS伏核对吗啡心理依赖大鼠行为学的影响.方法 40只大鼠同期依大鼠立体定向图谱行双侧伏核刺激电极的植入术,20只为吗啡假刺激组,20只为DBS组.术前(用药后第15天)、术后(刺激后第2～6天)对戒断症状进行评分,术前(用药后第15天)和术后(刺激后第2、4、6天)行条件性位置偏爱实验,研究大鼠的行为学变化40只大鼠成功地同期双侧伏核植入DBS刺激电极, 条件位置偏爱实验结果为吗啡成瘾大鼠在伴药箱平均停留时间长于非伴药箱,与生理盐水组比较具有统计学意义(P<0.01);DBS组与术前及吗啡假刺激组相比在伴药箱平均停留时间均明显缩短,具统计学意义(P<0.01),提示高频电刺激伏核能有效减轻大鼠吗啡心理依赖症状.术前戒断症状评分结果表明吗啡成瘾大鼠模型的成功建立(P<0.01);术后DBS大鼠的戒断症状与术前相比具统计学意义,证实DBS减轻了大鼠的躯体依赖症状.结论 高频刺激吗啡成瘾大鼠双侧伏核,能够有效地减轻大鼠吗啡心理依赖症状,为DBS伏核治疗吗啡等成瘾药物的心理依赖提供了实验依据.     

神经干细胞分化的神经元离子型谷氨酸受体NMDA亚单位的mRNA和蛋白表达

目的在体外研究由大鼠神经干细胞(NSCs)分化而来神经元细胞中离子型谷氨酸NMDA受体表达。方法分离培养孕14～16d胎鼠皮质和海马神经干细胞，对NSCs进行nestin和分化鉴定。通过RT—PCR、Western blot免疫印迹和免疫组化检测NSCs分化的神经元细胞中离子型谷氨酸NMDA受体亚单位NR1、NR2A和NR2B的mRNA和蛋白表达。结果从孕14～16d胎鼠大脑中分离培养出NSCs，NSCs分化后的神经元可以表达离子型谷氨酸NMDA受体亚单位NR1、NR2A和NR2B。结论由NSCs分化而来的神经元能表达离子型谷氨酸NMDA受体。     

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。     

毁损双侧伏隔核对大鼠吗啡条件性位置偏爱复燃的影响

目的探讨毁损双侧伏隔核对小剂量吗啡诱导大鼠条件性位置偏爱复燃的影响。方法设置毁损组、假毁损组及空白对照组(n=10),建立大鼠吗啡条件性位置偏爱模型,消退后采用立体定向下直流电(10mA,30s)毁损双侧伏隔核,分别在术后3d、10d、30d给予小剂量吗啡(2.5mg/kg)诱导复燃,观察记录各组大鼠条件性位置偏爱得分,采用方差分析及均数间多重比较进行统计学分析。结果条件性位置偏爱模型建立成功后,经消退各组位置偏爱得分间差异无统计学意义(P>0.05);毁损术后各时间点吗啡诱导复燃时,毁损组均较假毁损组的位置偏爱得分低(P<0.05),而毁损组各时间点间位置偏爱得分差异无统计学意义(P>0.05)。结论毁损双侧伏隔核可以抑制小剂量吗啡诱导的复燃,且此作用至少可维持30d。     

伏核脑深部刺激对吗啡成瘾心理依赖大鼠的作用研究

目的研究伏核脑深部刺激（DBS）对吗啡成瘾大鼠心理依赖的作用。方法将60只SD大鼠随机等分为三组：假刺激（ShS）组、DBS组、正常对照（NS）组。刺激前后行条件性位置偏爱实验，并观察伏核、海马、前额叶脑组织的形态学变化。结果刺激前DBS组与ShS组大鼠在伴药箱平均停留时间均长于NS组，差异显著（P〈0．01）；刺激后，DBS组较ShS组在伴药箱平均停留时间明显缩短（P〈0．01），而与NS组差异无统计学意义（P〉0．05）。刺激前，DBS组与ShS组大鼠伏核、海马神经元部分丢失，且水肿明显，细胞器减少；刺激后，DBS组较ShS组细胞水肿明显减轻，以伏核变化明显。结论伏核DBS有效治疗了大鼠的吗啡成瘾心理依赖作用。     

Changes in phosphorylation of CREB, ERK, and c-fos induction in rat ventral tegmental area, hippocampus and prefrontal cortex after conditioned place preference induced by chemical stimulation of lateral hypothalamus

Experimental evidence indicates that chemical stimulation of lateral hypothalamus (LH) by carbachol can produce conditioned place preference (CPP) in rats. Several lines of evidence have shown that cAMP-response element binding protein (CREB), extracellular signal-regulated kinase (ERK), and c-fos have pivotal role in CPP induced by drugs of abuse, such as morphine, cocaine, nicotine, and alcohol. Therefore, in the present study, we investigated the changes in phosphorylated-CREB (p-CREB) and -ERK (p-ERK), and c-fos induction within ventral tegmental area (VTA), hippocampus and prefrontal cortex (PFC) after the acquisition of CPP induced by intra-LH administration of carbachol. Animals were unilaterally implanted by cannula into LH. For chemical stimulation of LH, carbachol (250 nmol/0.5 μl saline) was microinjected once each day, during 3-day conditioning phase (acquisition period) of CPP paradigm. After the acquisition period, the brains were removed, and p-CREB and p-ERK, and c-fos induction in the ipsilateral VTA, hippocampus and PFC were measured by Western blot analysis. The results indicated a significant increase in level of phosphorylated CREB (P<0.01) in VTA, and PFC (P<0.05), during LH stimulation-induced CPP, while its level decreased in hippocampus (P<0.05). Also, in aforementioned regions, an increase in c-fos level was observed, but this enhancement in PFC was not significant. Moreover, p-ERK changed in these areas, but not significantly. Our findings suggest that studying the intracellular signals and their changes, such as phosphorylated-CREB, can elucidate a functional relationship between LH and other brain structures involved in reward processing in rats.     

大鼠伏隔核多巴胺D2受体及转运体与吗啡条件性位置偏爱易感性的关系

目的 探讨吗啡条件性位置偏爱(CPP)不同易感性的大鼠脑伏隔核多巴胺D2受体(D2R)和多巴胺转运体(DAT)水平.方法 将160只雄性Sprague-Dawley大鼠随机抽取30只作为对照组,余130只为吗啡组.对吗啡组在预测试后建立吗啡CPP模型.根据CPP值[以末次CPP测评时大鼠在伴药侧(大鼠注射吗啡后放入该侧,吗啡剂量从5 mg·kg-1·次-1开始逐渐增加,第10天为50 mg·kg-1·次-1)的停留时间减去预测试在该侧停留的时间]将吗啡组大鼠按比例分为高(26只)、中(78只)、低偏爱组(26只),其中高、低偏爱组(每组大鼠死亡各2只)分别于吗啡末次注射(对照组注射『司体积生理盐水)后3 h.3 d和14 d分别处死大鼠(每组各8只),用原位杂交法检测伏隔核D2R和DAT的灰度值(阳性区域的强弱与灰度值呈反比),并与对照组比较.结果 (1)预测试3组CPP值的差异无统计学意义(P>0.05);但在吗啡注射后3 h、戒断后3 d和14 d,高偏爱组CPP值[分别为(507±108)s、(524±113)s、(483±60)s]均长于低偏爱组[分别为(100±74)s、(166±86)s、(149±89)s;P=0.000]和对照组[分别为(97 ±111)s、(39±26)s、(-4.9 ±140.1)s;P=0.000].(2)上述各时点高偏爱组D2R mRNA灰度值(131 ±3、122±5、119±5)均高于低偏爱组(125±4、117±8、114±5)和对照组(11l±6、107±7、106±3;P<0.01);高偏爱组DAT mRNA灰度值(161±5、143±4、134±6)亦高于低偏爱组(156±5、139±3、130±4)和对照组(120±4、126±7、129±4;P<0.01).结论 大鼠吗啡CPP易感性高可能与伏隔核的D2R及DAT表达低下有关.     

Chronic nicotine and smoke treatment modulate dopaminergic activities in ventral tegmental area and nucleus accumbens and the gamma-aminobutyric acid type B receptor expression of the rat prefrontal cortex

Dopaminergic afferents from the mesencephalic areas, such as ventral tegmental area (VTA), synapse with the gamma-aminobutyric acid (GABA)-ergic interneurons in the prefrontal cortex (PFC). Pharmacological and electrophysiological data show that the reinforcement, the dependence-producing properties, as well as the psychopharmacologic effects of nicotine depend to a great extent on activation of nicotinic receptors within the mesolimbocortical dopaminergic projection. To explore further the relationship between the mesencephalic dopaminergic neurons and PFC GABAergic neurons, we investigated the effects of nicotine and passive exposure to cigarette smoke on the regulation of tyrosine hydroxylase (TH) in VTA and substantia nigra (SNC) and dopamine (DA) D1 receptor levels in nucleus accumbens (NAc) and caudate-putamen (CPu). Also, the simultaneous changes in GABAB receptors mRNAs in the PFC were studied. The results showed that chronic nicotine and smoking treatment differentially changed the levels of TH protein in VTA and SNC and DA D1 receptor levels in Nac and CPu. GABAB1 and GABAB2 receptor mRNA levels also showed different change patterns. Ten and thirty minutes of smoke exposure increased GABAB1 receptor mRNA to a greater extent than that of GABAB2, whereas GABAB2 was greatly enhanced after 1 hr of smoke exposure. The TH levels in VTA were closely related to DA D1 receptor levels in NAc and with GABAB receptor mRNA changes in PFC. These results suggest that the mesolimbic pathway and GABAB receptor mRNA in PFC are modulated by nicotine and cigarette smoke, implying an important role in nicotine's psychopharmacological effects.     

A lasting effect of postnatal sevoflurane anesthesia on the composition of NMDA receptor subunits in rat prefrontal cortex

Sevoflurane is widely used in pediatric anesthesia and studies have shown that it is capable of inducing neurodegeneration and subsequent cognitive disorders in the developing brain. However, the evidence that anesthetics are toxic to the human brain is insufficient. N-Methyl-d-aspartate (NMDA) receptors, critical for learning and memory, display expression changes with age and can be modulated by inhalation anesthetics. Generally, NMDA receptor (NR) type 1 is expressed at birth, peaks around the third postnatal week, and then declines slightly to adult levels. NR2Bs slowly decrease and NR2As gradually increase during postnatal development. These developmental switches of NMDA receptor subunits composition mark the transition from immature to adult neural processing and allow for the final maturation of associative learning abilities. In this study, we aimed to evaluate the effect of repeated sevoflurane anesthesia on NMDA receptor subunits composition in the developing rat brain and related behavioral disorders. Six-day-old male Sprague Dawley rats were randomly allocated into either a control group (group con) or a sevoflurane group (group sevo). Group sevo inhaled 2.1% sevoflurane carried by 70% oxygen for 2 h each day from postnatal day (PND) 6 to PND 8. The same procedure, without applying the sevoflurane, was executed in group con. The membrane protein expression of NR1, NR2A and NR2B in the prefrontal cortex (PFC) and hippocampus was assessed at the end of the three days of anesthesia and at PND 21. An open field test was carried out to assess spontaneous locomotion on PNDs 21, 28 and 35. Y maze performance was used to assess attention and working memory on PND 28. Sevoflurane induced upregulation of NR1 and NR2B in the PFC at the end of anesthesia. On PND 21, NR1 and NR2B receptors were significantly increased whereas NR2A receptors were significantly decreased in the PFC in group sevo. Sevoflurane-treated rats showed hyper-locomotion and impairment of working memory in the behavior tests. These results indicate that repeated sevoflurane anesthesia at early stage of life can induce a long lasting effect of interfering with NMDA receptor subunits composition in rat PFC. These changes may contribute to the effects of sevoflurane on neuronal development and subsequent neurobehavioral disorders.     

Role of D1/D2 dopamine receptors in the CA1 region of the rat hippocampus in the rewarding effects of morphine administered into the ventral tegmental area

Considerable evidences show that the VTA, as a major source of dopamine neurons projecting to cortical and limbic regions, has a major role in cognitive and motivating aspects of addiction. The current study assessed the ability of the selective D1 receptor antagonist SCH 23390 and D2 receptor antagonist sulpiride administrated into the CA1 region of hippocampus (dorsal hippocampus) to alter the rewarding effects of intra-VTA administration of morphine using the conditioned place preference (CPP). After bilaterally implantation of cannulae into the CA1 and/or VTA in adult male Wistar rats weighing 210-310 g, dose-response effects of different doses of intra-VTA morphine (0.03, 0.1, 0.3, 1 and 3 μg/side) on CPP paradigm were evaluated and animal displacement, conditioning score and locomotor activity were recorded by Ethovision software. In the next experiments, SCH 23390 (0.02, 0.05, 0.2 and 0.5 μg/side) or sulpiride (0.25, 0.75, 1.5 and 3 μg/side) were injected into the CA1, 5 min after intra-VTA injection of morphine during 3 days conditioning phase. Our results showed that intra-VTA morphine dose-dependently induces CPP in rats. Moreover, the blocking D1 and D2 receptors in the dorsal hippocampus decreased intra-VTA morphine-induced CPP significantly (P<0.01). Intra-CA1 administration of these antagonists alone, in all doses, could not induce CPP. We suggest that D1 and D2 receptors in the CA1 region of hippocampus have a key role in the development of CPP induced by morphine at the level of the VTA. It seems that there is an interaction between dopaminergic and opioidergic systems in these areas in reward circuit.     

Involvement of NMDA receptors in ryanodine receptor expression in dopaminergic neurons in the ventral tegmental area of mice with intermittent methamphetamine treatment

Excitatory synapses on dopaminergic neurons of the ventral tegmental area (VTA) represent an important role in psychostimulant-induced rewarding effect. This study investigated the regulation of ryanodine receptor (RyR) and N-methyl-D-aspartate (NMDA) receptor expression in mice under intermittent methamphetamine (METH) treatment using a place preference procedure. RyR-1 and -2 significantly increased in the VTA of mice with METH-induced place preference, whereas RyR-3 showed no changes. In addition, the levels of NR1, NR2A, and NR2B subunits were increased in the VTA. The METH-induced place preference was inhibited by intracerebroventricular pretreatment with MK-801, a noncompetitive NMDA receptor antagonist, and ifenprodil, a selective NR2B subunit-containing NMDA receptor antagonist, in a dose-dependent manner. Under these conditions, the increase of RyR-1 and -2 in the VTA was significantly blocked by ifenprodil. The immunohistochemical analysis revealed the colocalization of RyR-1 and -2 with NR2B subunits in dopaminergic neurons in the mouse VTA. These findings suggest that RyRs could be involved in the development of METH-induced place preference and that NR2B subunit-containing NMDA receptors in mice showing METH-induced place preference play an important role in expression of RyRs.     

Differential regulation of ionotropic glutamate receptor subunits following cocaine self-administration

Previous examination of binge cocaine self-administration and 2 week withdrawal from cocaine self-administration on ionotropic glutamate receptor subunit (iGluRs) protein levels revealed significant alterations in iGluR protein levels that differed between the mesocorticolimbic and nigrostriatal pathways. The present study was undertaken to extend the examination of cocaine-induced alterations in iGluR protein expression by assessing the effects of acute withdrawal (15-16 h) from limited access cocaine self-administration (8 h/day, 15 days). Western blotting was used to compare levels of iGluR protein expression (NR1-3B, GluR1-7, KA2) in the mesolimbic (ventral tegmental area, VTA; nucleus accumbens, NAc; and prefrontal cortex, PFC) and nigrostriatal pathways (substantia nigra, SN and dorsal caudate-putamen, CPu). Within the mesolimbic pathway, reductions were observed in NR1 and GluR5 immunoreactivity in the VTA although no significant alterations were observed in any iGluR subunits in the NAc. In the PFC, NR1 was significantly upregulated while GluR2/3, GluR4, GluR5, GluR6/7, and KA2 were decreased. Within the nigrostriatal pathway, NR1, NR2A, NR2B, GluR1, GluR6/7 and KA2 were increased in the dorsal CPu, whereas no significant changes were observed in the SN. The results demonstrate region- and pathway-specific alterations in iGluR subunit expression following limited cocaine self-administration and suggest the importance for the activation of pathways that are substrates of the reinforcing and motoric effects of cocaine.     

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。