大鼠吗啡精神依赖时伏核和前额叶皮质中NR2A、NR2B表达的变化

目的:建立条件性位置偏爱(CPP)模型,检测吗啡精神依赖大鼠伏核和前额叶皮质N-甲基-D-天冬氨酸受体(NMDA受体)调节亚基NR2A、NR2B表达的变化。方法:使用盐酸吗啡建立大鼠CPP。CPP形成后,每组大鼠5只灌注固定后进行免疫组织化学形态学检测,3只断头处死取伏核和前额叶皮质,并提取细胞膜蛋白进行Western blot定量检测。结果:吗啡诱导大鼠形成CPP时,前额叶皮质和伏核中NR2B有明显变化,免疫组织化学结果显示NR2B阳性细胞数明显增高(前额叶皮质P<0.05,伏核P<0.01)。Western blot结果显示NR2B蛋白表达量明显上调(前额叶皮质P<0.05,伏核P<0.01),而NR2A则无明显改变。结论:使用吗啡建立的大鼠CPP模型中,NMDA受体调节亚基NR2B在与奖赏作用密切相关脑区伏核和前额叶皮质中均有明显变化,而NR2A则无明显改变,表明NMDA受体中NR2B调节亚基在吗啡精神依赖形成中发挥着重要作用。     

金荞麦总黄酮下调NR2B表达改善IBS大鼠痛觉过敏

目的观察金荞麦总黄酮(Fag)对IBS样结肠刺激大鼠模型(CI模型)内脏敏感性的改善作用和对模型脊髓后角和海马内NMDA受体亚基NR2A、NR2B的影响。方法采用结肠刺激新生期乳大鼠法来制作IBS样CI模型。CI大鼠成年后给予口服Fag 2周,并用腹壁撤退反射(AWR)评分评价给药后CI大鼠内脏高敏感性的变化,用免疫组化法和蛋白印迹法进一步观察其脊髓后角和海马内NMDA受体亚基NR2A、NR2B的变化。结果和对照组比,CI组AWR评分明显增高,而高剂量Fag明显降低CI组的AWR评分。对照组脊髓后角、海马均可见NR2A、NR2B亚基表达,但CI组只有NR2B亚基表达增强,且高剂量Fag可降低其表达,NR2A亚基表达在各组变化不大。结论 Fag通过下调致敏中枢上脊髓后角和海马的NR2B表达对IBS样CI大鼠的痛觉过敏有改善作用。     

脊髓c-Jun在NMDA受体NR2B亚基介导的大鼠吗啡镇痛耐受中的作用

目的探讨脊髓c-Jun在N-甲基-D-天冬氨酸(N-meth-yl-D-aspartate,NMDA)受体NR2B亚基介导的吗啡镇痛耐受中的作用。方法取Sprague-Dawley(SD)成年大鼠连续7 d鞘内注射吗啡10μl(1.5 g.L-1)建立慢性吗啡镇痛耐受模型。应用热水甩尾法测定甩尾潜伏期(疼痛指标)以观察痛反应变化。应用免疫组织化学染色法检测磷酸化c-Jun(p-c-Jun)和总c-Jun(t-c-Jun)的表达。结果鞘内注射吗啡7 d,可激活大鼠脊髓的c-Jun,表现为神经元内p-c-Jun表达升高;鞘内注射NR2B选择性拮抗剂10μl Ro256981(2 g.L-1)可以抑制慢性吗啡镇痛耐受时脊髓神经元c-Jun的激活,并明显拮抗吗啡镇痛耐受的形成。结论脊髓神经元c-Jun的磷酸化参与NMDA受体NR2B亚基介导的吗啡镇痛耐受。     

伏核壳部含有GluN2B亚基的NMDA受体参与吗啡奖赏记忆的再巩固

目的:再次暴露于药物相关线索能唤起药物成瘾记忆并使之处于不稳定状态,此时可经再巩固后形成稳定记忆,也可干扰其再巩固过程削弱或消除该记忆。本研究检测了伏核内含有GluN2B亚基的NMDA受体在吗啡奖赏记忆再巩固中的作用。方法:将已形成吗啡条件性位置偏爱(conditioned place preference,CPP)的大鼠再次暴露于伴吗啡箱后,观察其伏核壳部和核心部NMDA受体各亚基的蛋白水平;再次暴露于伴吗啡箱后,在大鼠双侧伏核壳部和核心部分别注射GluN2B亚基选择性NMDA受体拮抗剂Ro 25-6981,观察对大鼠吗啡CPP表达的影响。结果:(1)吗啡CPP大鼠再次暴露于用药环境后,伏核壳部NMDA受体的GluN2B亚基蛋白水平特异性升高,Glu N2A亚基降低,Glu N1亚基不变;核心部GluN2B、Glu N2A和Glu N1亚基蛋白水平均无明显变化。(2)再次暴露于用药环境后,伏核壳部注射Ro 25-6981的大鼠没有表现出对伴吗啡箱的偏爱,这种对吗啡CPP的抑制作用可持续至给药后14 d,并且小剂量吗啡处理不能使CPP行为重建;核心部注射Ro 25-6981的大鼠仍可表现出对伴吗啡箱的偏爱。结论:伏核壳部含有GluN2B亚基的NMDA受体在吗啡奖赏记忆再巩固中发挥了重要的作用。     

吗啡长期给药后大鼠脑内MAO—B活性及咪唑啉受体的下调

目的:探讨吗啡长期给药处理后大鼠不同脑区MAO-B活性及咪唑啉受体含量的变化。方法:用[~3H]咪唑克生配体结合试验测定咪唑啉受体含量,用高效液相色谱法测定MAO-B活性。结果:咪唑克生和吗啡能剂量依赖性地抑制大鼠脑匀浆MAO-B活性。咪唑啉受体的内源性配体胍丁胺既不影响MAO-B活性,也不影响咪唑克生及吗啡对MAO-B活性的抑制作用。吗啡连续给药16d后大鼠大脑、海马、丘脑、纹状体及小脑内MAO-B活性均显著下调(P<0.01)。纳洛酮及咪唑克生单次给药对吗啡依赖大鼠上述脑区MAO-B活性均没有进一步影响;胍丁胺伴随吗啡给药后能显著抑制吗啡降低MAO-B活性的作用。吗啡连续给药后大鼠皮层和小脑咪唑啉受体数量减少而亲和力上调(P<0.05)或P<0.01)。结论:MAO-B活性与吗啡依赖大鼠发生戒断综合征相关,但与胍丁胺对吗啡镇痛作用的影响无关;胍丁胺对吗啡药理作用的影响与其激活咪唑啉受体有关。     

急性阿片耐受大鼠脊髓NMDA受体NR2A及NR2B亚基表达的改变

目的：了解大鼠短期多次应用芬太尼能否发生急性阿片耐受以及急性阿片耐受大鼠脊髓NMDA受体NR2A和NR2B亚基表达的改变。方法：24只体重为200-220g的雄性SD大鼠随机分为3组（n=8）：对照组（C）,生理盐水组（S）及芬太尼组（F）。F组大鼠给予皮下注射芬太尼30μg/kg,共4次,每两次注射之间间隔15min,S组大鼠以生理盐水代替芬太尼,C组大鼠未给药。给药前及给药结束后每30min以Von-Frey仪测定各组大鼠的机械刺激缩足阈值（paw withdrawal threshold,PWT）。当F组大鼠的PWT恢复到给药前基础水平时,各组大鼠均给予腹腔注射吗啡5mg/kg。随后仍每30min测定各组大鼠的PWT,直至F组大鼠的PWT再次回到基础水平。对各组大鼠不同时间点的PWT进行组内和组间比较。另24只体重为2000-220g的雄性SD大鼠分组及给药方法同前（分为C^＊、S^＊及F^＊组）,当F＊组大鼠的PWT首次恢复到基础值时,不给予吗啡,处死各组大鼠,取脊髓,以Western blotting方法测定NMDA受体NR2A及NR2B亚基的蛋白表达水平。结果：连续4次皮下注射芬太尼（F组）后大鼠首先表现为PWT较基础值显著升高,随后PWT降低到基础值以下,然后逐渐恢复至基础值水平,此时皮下注射吗啡后,吗啡的镇痛效果显著低于其他两组大鼠（S组,C组）。F^＊组大鼠脊髓的NR2B亚基表达水平显著高于C^＊组及S^＊组,各组大鼠脊髓的NR2A亚基表达水平的差异无统计学意义。结论：短期应用芬太尼可导致大鼠发生急性阿片耐受。急性阿片耐受大鼠的脊髓NMDA受体NR2B亚基表达水平显著升高,NR2A亚基表达水平无明显变化。     

N-甲基-D-门冬氨酸受体2B 亚基在抑郁症形成机制中作用的研究进展

抑郁症是一种精神科常见的疾病。它的临床特征以心境低落,快感缺失,负性思维和精力减退为核心,严重的可使患者的社会功能、职业功能下降,并给患者家庭、社会带来沉重的经济负担。目前抑郁症的确切发病机制尚不明确,但大部分学者认为边缘系统异常可能是抑郁症发病的主要原因,其中海马作为边缘系统的重要组成部分,在抑郁形成中发挥重要作用。NMDA受体是广泛分布于中枢神经系统的离子型谷氨酸受体,主要由NR1、NR2（A、B、C和D）和NR3（A和B）3种亚型组成,在神经元可塑性,情绪调节过程中发挥着重要作用［1］,其NR2B亚基主要分布于前脑区如海马和纹状体,与情绪调节密切相关［2］。在强迫游泳实验制备的抑郁模型中,大鼠海马中含有NR2 B亚基的NMDA受体（ NR2 B ）表达水平明显升高,而NR2 A水平未见明显改变,而给予NMDA受体拮抗剂氯胺酮可以降低NR2 B水平改善抑郁症状;同样在大鼠抑郁模型中,有研究发现在给予氯胺酮以及NR2 B受体特异性拮抗剂后,大鼠抑郁症状明显改善［3］。这些研究均提示NR2 B尤其是海马NR2 B的表达变化在抑郁形成过程中发挥重要作用,因此本文拟对NR2 B在抑郁形成中的作用研究进展作一综述。     

大鼠吗啡条件性位置偏爱期间前额叶皮质和伏隔核中GluR1、GluR2阳性神经元的变化

目的:研究吗啡依赖期间大鼠前额叶皮质和伏隔核中GluR1、GluR2阳性神经元的变化。方法:采用免疫组织化学实验方法观察吗啡条件性位置偏爱模型大鼠前额叶皮质和伏隔核中GluR1和GluR2阳性神经元的形态及数目变化。结果:与空白对照组比较,吗啡模型组GluR1和GluR2的阳性神经元数均明显升高(P<0.01)。结论:大鼠条件性位置偏爱期间前额叶皮质和伏隔核中GluR1和GluR2的阳性神经元增多,提示AMPA受体GluR1和GluR2两个亚基参与了吗啡精神依赖的形成。     

吗啡依赖大鼠伏隔核与海马腹侧下托放电频率的改变

目的:用胞外记录的方法分别观察伏隔核和海马腹侧下托对吗啡的反应性,探讨其在药物心理依赖形成过程中所处的地位。方法:吗啡依赖大鼠及正常大鼠各10只,依照大鼠脑立体定向图谱,将电极下至将要记录核团附近,依次注射吗啡、纳洛酮,观察各核团对药物的反应性。结果:吗啡依赖组大鼠伏隔核放电频率从15Hz±s3Hz变化至<3Hz甚至放电中断,正常组大鼠从6Hz±s2Hz变化至0·5-3Hz;吗啡依赖组大鼠海马腹侧下托放电频率7Hz±s2Hz变化不明显,正常组放电频率6Hz±s2Hz变化不明显。结论:在药物心理依赖形成过程中,伏隔核发生了较明显的变化,而海马腹侧下托变化不明显。     

气体信号分子H2S对大鼠记忆行为的影响及机制

目的硫化氢(H2S)是一种内源性气体信号分子,在生物体内发挥着广泛的生物学效应。中枢神经系统的H2S作为一个突触调节分子,具有神经保护作用。有研究发现,额颞叶退变性疾病和阿尔茨海默病患者可出现杏仁核依赖的情感记忆异常。神经退行性疾病(如阿尔茨海默病、帕金森病等)患者或动物大脑H2S含量出现异常。但目前对于H2S与学习记忆和情感记忆的关系尚未有相关的报道。本实验研究气体信号分子H2S在大鼠海马区和杏仁核区介导的记忆行为中的作用及机制。方法条件性恐惧记忆和新事物认知实验观察大鼠的记忆行为;脑片膜片钳和场电位技术记录NMDA受体介导的电流及LTP;Western blotting实验研究突触可塑性相关蛋白的表达水平。结果条件性和线索性恐惧学习训练均可明显增加大鼠海马区H2S的含量。H2S合成酶抑制剂可损伤海马依赖的情景性恐惧记忆,和杏仁核依赖的线索性恐惧记忆。外源性补充H2S可剂量依赖性的增强大鼠的记忆行为。同样,外源性给予H2S也可明显增强杏仁核依赖的条件性味觉厌恶记忆,以及海马依赖的新物体认知功能。电生理实验发现,H2S选择性增强海马区含NR2A亚基的NMDA受体介导的电流和NMDA受体依赖的海马LTP;且NR2A特异性阻断剂可取消H2S对LTP和认知功能的增强作用。但选择性增强丘脑-杏仁核通路含NR2B亚基的NMDA受体所介导的电流及NMDA受体依赖性LTP。H2S增强学习记忆的作用与PKA,PKC,CaMKⅡ和CREB等信号通路激活有关。结论作为一种内源性气体信号分子,H2S在海马和杏仁核依赖的记忆行为中扮演着重要角色,为将H2S释放药物开发成为治疗情感障碍性疾病的药物提供新思路。     

Nucleus accumbens NMDA receptor subunit expression and function is enhanced in morphine-dependent rats

We have previously shown, using radioligand binding studies, that N-methyl-d-aspartate (NMDA) NR1 and NR2A receptor subunits density was decreased in the forebrain of morphine-dependent rats. We have now determined if morphine-dependent rats display regional differences in NMDA receptor expression and whether such changes are functionally relevant. In morphine-dependent rats, the expression of NR1 and NR2A subunits protein, as determined by Western blotting with NMDA receptor subunit antibodies, were decreased in frontal cortex and hippocampus but significantly increased in the nucleus accumbens. The expression of the NR2B subunit was unchanged in all regions examined. In separate groups of morphine-dependent rats, MK-801-induced hyperactivity (thought to be mediated via modulation of nucleus accumbens dopamine release) was significantly enhanced in morphine-dependent animals. Similarly, the MK-801-induced increase of dopamine metabolism was significantly increased in the nucleus accumbens of morphine-dependent animals as compared to sham controls. Results provide both biochemical and behavioural evidence to suggest that NMDA receptor function in the nucleus accumbens, at least with respect to an interaction with the limbic dopamine system, is markedly enhanced in morphine-dependent rats. This increase in function may be associated with an enhanced expression of NMDA receptors, particularly those in the nucleus accumbens containing the NR2A subunit. Taken together, these data support several studies in the literature indicating that NMDA receptors in the nucleus accumbens are involved in the process of opiate dependence.     

Agmatine modulates neuroadaptations of glutamate transmission in the nucleus accumbens of repeated morphine-treated rats

It has been proved that agmatine inhibits opioid dependence, yet the neural mechanism remains unclear. In the present study, the effect of agmatine on the neuroadaptation of glutamate neurotransmission induced by morphine dependence, including changes of the extracellular glutamate level and glutamate receptors in the nucleus accumbens was investigated.We found that agmatine (2.5–20 mg/kg, s.c.) inhibited development of morphine dependence, which was consistent with our previous report. In rats repeatedly treated with morphine, the glutamate level in the nucleus accumbens dialysate was markedly increased after naloxone-precipitated withdrawal. When agmatine (20 mg/kg, s.c.) was co-pretreated with morphine or was applied before naloxone-precipitated withdrawal, this elevation of the extracellular glutamate level was inhibited. In the synaptosome model, repeated morphine treatment and naloxone precipitation induced an increase in glutamate release, while agmatine (20 mg/kg, s.c.) co-pretreated with morphine reversed the increase of glutamate release. However, neither morphine or agmatine treatment alone nor morphine and agmatine co-administration had any influence on [3H]-glutamate uptake. It indicated that the elevation of the glutamate level in the nucleus accumbens might be caused by the increase of glutamate release of synaptosome in the withdrawal conditions of morphine-dependent rat. Furthermore, agmatine concomitant treatment with morphine entirely abolished the up-regulation of the NR1 subunit of N-methyl-d-aspartate (NMDA) receptors in the nucleus accumbens in repeated morphine-treated rats.Taken together, the present study demonstrated that agmatine could modulate the neuroadaptations of glutamate transmission in the nucleus accumbens in the case of morphine dependence, including modulating extracellular glutamate concentration and NMDA receptor expression.     

Gender-selective effects of ethanol dependence on NMDA receptor subunit expression in cerebral cortex, hippocampus and hypothalamus

Previous investigations have shown subunit-selective alterations in NMDA receptors in ethanol dependent male rats. In the present study, we found pronounced gender differences in the effects of ethanol dependence on NMDA receptor subunit expression in all brain regions investigated. Ethanol dependent female rats exhibited increased NR1 subunit levels in cerebral cortex and hypothalamus, whereas males displayed increased NR1 levels only in hippocampus. NR2A subunit levels were significantly increased only in hippocampus from ethanol dependent male rats, whereas NR2B subunit levels significantly increased in cerebral cortex of both female and male rats. These findings suggest that gender influences neuroadaptations elicited by ethanol dependence at the level of NMDA receptor subunit expression.     

Mechanisms of morphine-induced rewarding effect: involvement of NMDA receptor subunits

The glutamate receptor contributes to excitatory synaptic transmission in the central nervous system and plays an important role in memory acquisition, learning and neurological disorders. Molecular cloning studies have revealed that NMDA receptors consist of two families, the NR1 and NR2A-NR2D subunits, and NMDA receptors are thought to be pentameric or tetrameric complexes of the NR1 subunit with one or more of the NR2 subunits. It has been proposed that NMDA receptors are implicated in the development of opioid dependence. The non-selective NMDA receptor antagonist dizocilpine has been shown to suppress not only physical but also psychological dependence produced by morphine. An intracerebroventricular (i.c.v.) treatment with a specific antibody against the carboxyl-terminal region of the NR2B subunit abolishes the morphine-induced place preference, whereas antibodies against the NR1 and NR2A subunits do not affect the rewarding effect of morphine, indicating that the blockade of the NR2B subunit suppresses the development of the morphine-induced rewarding effect. Under these conditions, the NR2B subunit protein is up-regulated in the limbic forebrain of morphine-conditioned mice. These findings suggest that the NMDA receptor, especially NR2B subunit, is an important modulator of the development and/or expression of psychological dependence on morphine.     

Estrogen-like activity of tamoxifen and raloxifene on NMDA receptor binding and expression of its subunits in rat brain.

Hormonal specificity of modulation of N-methyl- D-aspartate (NMDA) receptors was investigated by comparing the effects of estradiol with tamoxifen or raloxifene, which display different responses in breast, bone, and uterus. Two weeks ovariectomy in rats decreased uterine weight, which was prevented by a two-week estradiol treatment; tamoxifen and raloxifene had weaker uterine stimulation than estradiol. Ovariectomy in rats decreased L-[3H]glutamate specific binding to NMDA receptors in CA1 and dentate gyrus but not CA2/3 regions of hippocampus and was without effect in cortex, striatum, nucleus accumbens, and olfactory tubercle. [3H]Ro 25-6981 (an NMDA antagonist selective for NR1/NR2B assembly) specific binding and mRNA levels of NMDA receptor subunits 1 and 2B decreased in CA1 after ovariectomy. Estradiol, tamoxifen, and raloxifene decreased L-[3H]glutamate specific binding to NMDA receptors and [3H]Ro 25-6981 specific binding in cortical area of ovariectomized rats and prevented the decrease of [3H]glutamate specific binding to NMDA receptors in CA1 and dentate gyrus, as well as [3H]Ro 25-6981 specific binding in CA1. Estradiol prevented the decrease of NMDA receptor subunits 1 and 2B mRNA levels in CA1 only; tamoxifen and raloxifene prevented the decrease of NMDA receptor subunit 1 mRNA levels in CA1. No effect of ovariectomy or treatments on L-[3H]CGP 39653 (an NMDA antagonist selective for NR1/NR2A assembly) specific binding and NMDA receptor subunit 2A mRNA levels was observed in all brain regions assayed. Our results showed brain regional and subunits specific agonist estrogenic activity of tamoxifen and raloxifene on NMDA receptors.     

Opiate physical dependence and N-methyl-d-aspartate receptors

The present review focused the involvement of N-methyl-d-aspartate (NMDA) receptors in morphine physical dependence. The increased levels of extracellular glutamate, NMDA receptor ζ subunit (NR1) mRNA, NMDA receptor 1 subunit (NR2A) protein, phosphorylated Ca²⁺/calmodulin kinase II (p-CaMKII) protein, c-fos mRNA, c-Fos protein, are observed in the specific brain areas of mice and/or rats showing signs of naloxone-precipitated withdrawal. In preclinical and clinical studies, a variety of NMDA receptor antagonists and pretreatment with an antisense oligonucleotide of the NR1 have been reported to inhibit the development, expression and/or maintenance of opiate physical dependence. In contrast to data obtained in adult animals, NMDA receptor antagonists are neither effective in blocking the development of opiate dependence nor the expression of opiate withdrawal in neonatal rats. In the NMDA receptor-deficient mice, the NR2A knockout mice show the marked loss of typical withdrawal abstinence behaviors precipitated by naloxone. The rescue of NR2A protein by electroporation into the nucleus accumbens of NR2A knockout mice reverses the loss of abstinence behaviors. The activation of CaMKII and increased expression of c-Fos protein in the brain of animals with naloxone-precipitated withdrawal syndrome are prevented by NMDA receptor antagonists, whereas the increased levels of extracellular glutamate are not prevented by them. These findings indicate that glutamatergic neurotransmission at the NMDA receptor site contributes to the development, expression and maintenance of opiate dependence, and suggest that NMDA receptor antagonists may be a useful adjunct in the treatment of opiate dependence.     

Protective effect of gan mai da zao decoction in unpredictable chronic mild stress-induced behavioral and biochemical alterations

Aim: Growing evidence indicates that the glutamatergic system, especially the abnormalities of glutamate and N-methyl-D-aspartate (NMDA) receptors contribute to the pathophysiology and possibly the pathogenesis of major depressive disorders. This study is to evaluate the effect of gan mai da zao (GMDZ) decoction on glutamate and NMDA receptor in unpredictable chronic mild stress (UCMS) rats.

Materials and methods: Sucrose preference test and open field test were used to estimate the depressive-like behaviors of UCMS rats. Glutamate levels and NMDA receptor subunits (NR1, NR2A and NR2B) in the frontal cortex and hippocampus were determined by HPLC-FLD and by western-blot respectively.

Results: 32 days UCMS induced depressive-like behaviors, increased glutamate concentration and decreased NMDA receptor subunits NR2A and NR2B in the frontal cortex and hippocampus of rats. However, NR1 expression remained constant in stressed rats compared with normal. The GMDZ decoction alleviated the depressive-like behavior, decreased glutamate level, and increased expression of NMDA receptor subunit NR2A and NR2B in the frontal cortex and hippocampus of stressed rats.

Conclusions: These results suggest that GMDZ treatment reversed chronic unpredictable stress-induced depressive-like behaviors in UCMS rats, possibly via reducing glutamate levels and increasing the NMDA receptor subunits NR2A and NR2B in frontal cortex and hippocampus.     

Opiate physical dependence and N-methyl-D-aspartate receptors

The present review focused the involvement of N-methyl-D-aspartate (NMDA) receptors in morphine physical dependence. The increased levels of extracellular glutamate, NMDA receptor zeta subunit (NR1) mRNA, NMDA receptor epsilon 1 subunit (NR2A) protein, phosphorylated Ca(2+)/calmodulin kinase II (p-CaMKII) protein, c-fos mRNA, c-Fos protein, are observed in the specific brain areas of mice and/or rats showing signs of naloxone-precipitated withdrawal. In preclinical and clinical studies, a variety of NMDA receptor antagonists and pretreatment with an antisense oligonucleotide of the NR1 have been reported to inhibit the development, expression and/or maintenance of opiate physical dependence. In contrast to data obtained in adult animals, NMDA receptor antagonists are neither effective in blocking the development of opiate dependence nor the expression of opiate withdrawal in neonatal rats. In the NMDA receptor-deficient mice, the NR2A knockout mice show the marked loss of typical withdrawal abstinence behaviors precipitated by naloxone. The rescue of NR2A protein by electroporation into the nucleus accumbens of NR2A knockout mice reverses the loss of abstinence behaviors. The activation of CaMKII and increased expression of c-Fos protein in the brain of animals with naloxone-precipitated withdrawal syndrome are prevented by NMDA receptor antagonists, whereas the increased levels of extracellular glutamate are not prevented by them. These findings indicate that glutamatergic neurotransmission at the NMDA receptor site contributes to the development, expression and maintenance of opiate dependence, and suggest that NMDA receptor antagonists may be a useful adjunct in the treatment of opiate dependence.     

钩藤碱对苯丙胺依赖大鼠伏核和杏仁核中NR2B蛋白表达的影响

目的:研究钩藤碱对苯丙胺依赖大鼠伏核和杏仁核中NR2B蛋白表达的影响。方法:采用条件性位置偏爱实验和免疫组化技术。结果:(1)建立了苯丙胺(2mg.kg-1,连续4d)诱导的位置偏爱模型,氯胺酮及钩藤碱低、中、高剂量均可消除苯丙胺诱导的位置偏爱效应,随钩藤碱剂量增加其效应加强,且本身无精神依赖性;(2)苯丙胺模型组大鼠伏核和杏仁核NR2B蛋白表达增加,氯胺酮及钩藤碱中、高剂量抑制NR2B表达,低剂量及本身对NR2B表达无影响。结论:伏核和杏仁核NR2B蛋白表达参与了钩藤碱抗苯丙胺依赖作用的分子机制。     

Therapeutic effect of ifenprodil,a NMDA receptor antagonist,on drug dependence

Although drug dependence has been treated by the adonist-therapy,the specific drug therapy for drug dependence has not been established.Ifenprodil is consibdred to specifically block the NMDA receptor consisted of NR1/NR2B subunits without undesirable adverse reactions,such as psychotomimetic action and psychological dependence,while ketamine and MK-801 can block both NMDA receptors consisted of NR1/NR2A and NR1/NR2B subunits with the undesirable adverse reactions.In the present study,we designed to examine the effect of ifenprodil on drug dependence in rodents.Pretreatment with ifenprodil suppressed the expression of withdrawal signs in morphine-, diazepam-and alcohol-dependent rats and mics.Rewarding effects of morphine,methamphetamine and cocaine as well as physical dependence,were suppressed by pretreatment with ifenprodil in rats and mice.These results suggest that ifenprodil be useful in treating drug dependence.