海洛因成瘾易感性与腹侧被盖区多巴胺D2受体及多巴胺转运体的关系

目的建立大鼠海洛因成瘾易感性差异模型,探讨其可能的腹侧被盖区(VTA)D2受体(D2R)及多巴胺转运体(DAT)机制。方法 130只雄性SD大鼠随机分为海洛因成瘾组(n=100)和对照组(n=30)接受7d的条件性位置偏爱(CPP)训练和2d的测评,期间两组分别给予海洛因和生理盐水注射处理。此后,成瘾组根据海洛因诱导的CPP强度挑选出高CPP组(n=30)和低CPP组(n=30)。各组大鼠再随机分为5组,在接受末次处理后分别于成瘾期、戒断第1、3、7、14天检测VTA区D2R和DAT的蛋白表达,蛋白检测采用免疫组织化学法。结果与对照组相比,高CPP组和低CPP组大鼠在成瘾期VTA区D2R和DAT蛋白表达均下降(P0.05);戒断后第1、3、7、14天D2R及戒断第1、3天DAT仍低于对照组(P0.05),而戒断第7、14天高、低CPP组分别与对照组的DAT差异均已无统计学意义(P0.05);在所有检测时点,高CPP组VTA区D2R下调均比低CPP组大鼠更为明显(P0.05),而两组的DAT表达差异均无统计学意义(P0.05)。结论海洛因慢性处理可诱导大鼠VTA区D2R和DAT下调;而海洛因成瘾易感性可能与VTA区低D2R有关,但未见与DAT相关。     

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.     

脑深部电刺激对吗啡心理依赖大鼠伏核多巴胺受体的影响

目的探讨脑深部电刺激(DBS)对大鼠双侧伏核多巴胺D1A受体(D1AR)和D2受体(D2R)表达的影响以及多巴胺受体(DAR)在DBS治疗吗啡心理依赖中的作用。方法将60只SD大鼠随机分为假刺激组(ShS组)、电刺激组(DBS组)和生理盐水对照组(NS组),20只/组。用免疫组化法和RT-PCR法检测各组大鼠伏核多巴胺D1AR和D2R表达的变化。结果ShS组伏核D1AR阳性细胞数较NS组、DBS组明显增多(P0.01),而DBS组与NS组比较,差异无统计学意义(P0.05);三组间D1ARmRNA比较,差异无统计学意义(P0.05)。DBS组大鼠D2R阳性细胞数较NS组明显下降(P0.01),但较ShS组明显上升(P0.01);ShS组大鼠伏核D2RmRNA较NS组及DBS组显著上升(P0.01),而DBS组与NS组比较,差异无统计学意义(P0.05)。结论DBS对吗啡心理依赖大鼠伏核D1AR和D2R的表达起反向调节作用。     

基底外侧杏仁核和隔内侧核毁损对精神分裂症大鼠行为学及中脑D2受体的影响

目的 探讨立体定向基底外侧杏仁核(BLN)和隔内侧核(MS)的联合毁损对甲基苯丙胺(MAP)大鼠中脑脑区多巴胺D2受体(D2DR)表达的影响.方法 48只SD大鼠随机分为对照组、模型组、假手术组、基底外侧杏仁核毁损组(BLN组)、隔内侧核毁损组(MS组)、基底外侧杏仁核与隔内侧核联合毁损组(BLN MS组),每组各8只;采用经腹腔注射MAP制备精神分裂症MAP模型,立体定向--直流电毁损BLN和MS,原位杂交法观察中脑脑区D2DR的表达.结果 与对照组比较,模型组及假手术组大鼠中脑D2DR表达有非常显著性差异(P<0.01); BLN组、MS组及(BLN MS)组中脑D2DR阳性细胞数目与显著低于模型组(P<0.01).结论 BLN和MS的联合毁损可以抑制使用MAP而诱发的中脑D2DR表达的亢进.     

烟碱上调大鼠脑纹状体多巴胺D1受体mRNA表达诱导其行为改变

目的　 通过观察烟碱对大鼠脑纹状体D1,D2 受体mRNA表达的影响 ,研究烟碱诱导大鼠行为改变的可能机制 ,以进一步探讨烟碱对帕金森病具有保护效应的作用机理。 方法 SD大鼠 2 4只 ,随机分为生理盐水组(12只 )、烟碱组 (12只 )。分别给予生理盐水、烟碱 4mg/kg·d,2次 /d ,共 14d。每次注射药物后 0 .5h观察大鼠行为活动 ,并于末次注射药物后 0 .5h处死动物 ,快速分离纹状体 ,采用RT PCR方法检测大鼠纹状体D1,D2 受体mRNA的表达。结果 烟碱组大鼠于用药后第 3天 ,出现走动增多 ,易激惹 ,定型活动明显 ,并于第 714天达到高峰。在大鼠纹状体内 ,烟碱组D1受体mRNA表达比对照组上升 2 3% (分别为 98.6 3± 1.13,6 5 .2 9± 1.4 5 ,P <0 .0 1) ,两组D2 受体mRNA的表达无显著性差异 (P >0 .0 1)。 结论 烟碱可能通过上调大鼠纹状体D1受体mRNA的表达而诱导大鼠理毛、张口等行为改变 ;烟碱可能有部分D1受体激动样作用。     

帕金森病大鼠模型尾壳核多巴胺D2受体活性变化研究

目的：探讨帕金森病病程中多巴胺D2受体的活性变化及其规律。方法：在建立6－羟基多巴胺毁损的帕金森病大鼠模型基础上，应用放射配基结合分析法结合Scanchard作图，测定不同时间点模型大鼠及对照大鼠尾壳核多巴胺D2受体的最大结合容量（Bmax)和平衡解离常数（KD）。结果：大鼠模型毁损侧尾壳核多巴胺D2受体Bmax显著升高，而KD值显著降低，在1个月时达到高峰，受体的亲合力显著增高。结论：帕金森病大鼠模型毁损侧尾壳核存在D2受体上行调节，D2受体明显超敏。     

大鼠慢性吗啡处理后不同时间部分脑区腺苷酸环化酶Ⅷ基因表达的变化

目的　研究慢性吗啡处理的大鼠停药后不同时间部分脑区腺苷酸环化酶Ⅷ (ACⅧ )基因表达水平的变化。方法　将 2 4只雄性Sprague Dawley大鼠随机等分为吗啡依赖组 (吗啡组 ;在大鼠腹腔内注射盐酸吗啡 ,2次 /d ;起始剂量为 5mg/kg ,逐日递增 5mg ,至第 10天为 5 0mg/kg)及生理盐水对照组 (对照组 ;用相同方式注射同体积的生理盐水 ) ,于末次注射后 3h及 72h处死 (每组每时间点各 6只 ) ,取中脑腹侧被盖区 (VTA)、伏隔核 (NAc)、中脑导水管灰质 (PAG)、杏仁核 (AMG)、海马CA1区 (HIPCA1)等脑组织。利用组织原位杂交技术检测各脑区ACⅧmRNA的吸光度 (A)值 ,并作同期平行比较。结果　 (1)末次注射 3h ,吗啡组NAc、PAG、AMG、HIPCA1的A值 (依次为 0 2 4 8±0 0 0 7、0 2 5 6± 0 0 11、0 2 6 8± 0 0 2 0、0 2 79± 0 0 16 )高于对照组 (依次为 0 2 34± 0 0 11、0 2 4 0±0 0 11、0 2 4 0± 0 0 11、0 2 5 1± 0 0 13;P <0 0 5～ 0 0 1) ,两组VTA的A值的差异无显著性 (P >0 0 5 )。 (2 )末次注射 72h ,吗啡组NAc、AMG的A值 (0 2 4 3± 0 0 0 7、0 2 5 2± 0 0 0 7)高于对照组(0 2 2 5± 0 0 12、0 2 2 5± 0 0 11;P <0 0 1) ,VTA、PAG的A值 (0 2 30± 0 0 10、0 2 2 8± 0 0     

杏仁核和扣带回毁损对甲基苯丙胺大鼠边缘区多巴胺受体的影响

目的　探讨立体定向杏仁核和扣带回的联合毁损对甲基苯丙胺 (MAP)大鼠脑内边缘区多巴胺D2受体表达的影响。方法　 4 0只SD大鼠随机分为对照组、MAP组、MAP加毁损组和MAP加假毁损组 ,每组各 10只 ;采用经腹腔注射MAP制备精神分裂症MAP模型 ,立体定向 射频毁损杏仁核和扣带回 ,免疫组织化学ABC法观察边缘区D2受体的表达。结果　与对照组比较 ,MAP组及MAP加假毁损组大鼠边缘区D2受体表达有非常显著性差异(P <0 0 1) ;MAP加毁损组大鼠边缘区D2受体阳性细胞数目与对照组比较无显著性差异 (P <0 0 1)。结论　杏仁核和扣带回的联合毁损可以抑制使用MAP而诱发的边缘区D2表达的亢进。     

杏仁核毁损对甲基苯丙胺精神分裂症大鼠边缘区多巴胺D2受体的影响

目的探讨立体定向杏仁核毁损对甲基苯丙胺(methamphetamine,MAP)精神分裂症大鼠脑内边缘区多巴胺D2受体表达的影响.方法40只SD大鼠随机分为对照组、模型组、假手术组和手术组,每组各10只;采用经腹腔注射MAP制备精神分裂症MAP模型,立体定向-射频毁损杏仁核,原位杂交法观察边缘区多巴胺D2受体的表达.结果与对照组比较,模型组及假手术组大鼠边缘区多巴胺D2受体表达有非常显著性差异(P＜0.01);手术组大鼠边缘区多巴胺DA受体阳性细胞数目与对照组比较差异无显著性(P＜0.01).结论杏仁核毁损可以抑制使用MAP而诱发的边缘区D2表达的亢进.     

吗啡精神依赖大鼠相关脑区细胞外氨基酸类神经递质的变化

目的 研究吗啡精神依赖大鼠伏隔核(NAc)、苍白球腹侧核(VP)以及中脑腹侧被盖区(VTA)中细胞外谷氨酸(Glu)和γ-氨基丁酸(GABA)含量的变化. 方法 18只Wisar大鼠按照随机数字表法分为对照组(8只)和吗啡组(10只).吗啡组大鼠每日皮下注射盐酸吗啡,并进行位置偏爱(CPP)训练,10 d后停药,戒断躯体依赖后行CPP评分;对照组大鼠在相同时间给予同体积的生理盐水皮下注射10d.停药一周后用微透析探针对大鼠NAc、VP和VTA行微透析,用高效液相色谱法(HPLC)测定透析液中的Glu和GABA的含量. 结果 吗啡组NAc中细胞外Glu含量明显高于对照组,差异有统计学意义(P＜0.05),两组VP和VTA中细胞外Glu和GABA含量比较差异有统计学意义. 结论 Glu在维持精神依赖的过程中发挥重要作用.     

吗啡依赖大鼠脑内相关脑区CREB mRNA的表达

目的　观察吗啡依赖和戒断时大鼠脑内转录因子CREBmRNA的变化。方法　采用逆转录PCR(RT PCR)方法 ,对CREBmRNA在吗啡依赖和戒断时大鼠脑内与阿片类物质依赖有关的前额叶皮质、海马、伏隔核和新纹状体等脑区的表达进行观察。结果　吗啡依赖和戒断时前额叶皮质以及吗啡戒断时新纹状体CREBmRNA的光密度值高于对照组 ,海马、伏隔核等处无改变。结论　吗啡依赖和戒断时CREBmRNA在某些脑区的表达升高 ,提示CREB可能与阿片类物质依赖的形成有关。     

吗啡成瘾大鼠伏核电刺激前后多巴胺含量的变化

目的观察吗啡成瘾大鼠在伏核电刺激前后伏核多巴胺（DA）含量的变化。方法40只实验大鼠随机分为假刺激组（ShS组）、刺激组（DBS组）、吗啡成瘾组（MA组）和生理盐水对照组（NS组）。MA组、ShS组和DBS组大鼠通过腹腔注射盐酸吗啡建立吗啡成瘾大鼠动物模型,NS组大鼠相同方法注射同体积生理盐水。随后ShS组和DBS组大鼠进行双侧伏核电极植入,建立吗啡成瘾大鼠电刺激伏核模型,其中DBS组大鼠进行伏核电刺激。取各组大鼠伏核,利用高效液相色谱-电化学检测法（HPLC-ECD）检测伏核DA含量。结果MA组大鼠伏核DA含量明显高于NS组（P〈0．01）和DBS组（P〈0．01）;ShS组大鼠伏核DA含量与MA组相比无明显差异。结论吗啡成瘾大鼠伏核DA含量增加,经过双侧伏核电刺激后DA含量降低,提示伏核电刺激对药物成瘾心理依赖的效应可能通过降低DA释放而起作用。     

Gene expression in dopamine and GABA systems in an animal model of schizophrenia: effects of antipsychotic drugs

We used in situ hybridization histochemistry to assess expression of dopamine receptors (D1R, D2R and D3R), neurotensin, proenkephalin and glutamate decarboxylase‐67 (GAD67) in the prefrontal cortex, striatum, and/or nucleus accumbens in adult rats with neonatal ventral hippocampal (VH) lesions and in control animals after acute and chronic treatment with antipsychotic drugs clozapine and haloperidol. We also acquired these measures in a separate cohort of treatment‐naïve sham and neonatally VH‐lesioned rats used as an animal model of schizophrenia. Our results indicate that the neonatal VH lesion did not alter expression of D1R, D3R, neurotensin or proenkephalin expression in any brain region examined. However, D2R mRNA expression was down‐regulated in the striatum, GAD67 mRNA was down‐regulated in the prefrontal cortex and prodynorphin mRNA was up‐regulated in the striatum of the VH‐lesioned rats as compared with sham controls. Antipsychotic drugs did not alter expression of D1R, D2R or D3R receptor mRNAs but elevated neurotensin and proenkephalin expression in both groups of rats; patterns of changes were dependent on the duration of treatment and brain area examined. GAD67 mRNA was up‐regulated by chronic antispychotics in the nucleus accumbens and the striatum and by chronic haloperidol in the prefrontal cortex in both sham and lesioned rats. These results indicate that the developmental VH lesion changed the striatal expression of D2R and prodynorphin and robustly compromised prefrontal GAD67 expression but did not modify drug‐induced expression of any genes examined in this study.     

Methamphetamine decreases calcium-calmodulin dependent protein kinase II activity in discrete rat brain regions

A Ca(2+)/calmodulin-dependent signaling cascade has been implicated in the regulation of dopaminergic neurotransmission after chronic administration of amphetamine and methamphetamine (METH). We found a decrease in Ca(2+)/calmodulin-dependent protein kinase II (CaM-kinase II) activity in five regions of the rat brain (parietal cortex; frontal cortex; hippocampus; striatum; and nucleus accumbens) after a single injection of METH. Pretreatment with the selective dopamine D1 receptor antagonist SCH 23390 prevented the acute METH-induced decrease in CaM-kinase II activity in the parietal cortex, striatum, nucleus accumbens, and substantia nigra/ventral tegmental area (SN/VTA). Pretreatment with the N-methyl-D-aspartate receptor antagonist MK-801 significantly restored the acute METH-induced decrease in CaM-kinase II activity in the parietal cortex, nucleus accumbens, and SN/VTA. Striatal CaM-kinase II activity was still significantly lower than that of the chronic saline-treated controls after a 1-week, but not a 4-week, abstinence from chronic administration of METH. A METH challenge after a 4-week abstinence period induced a more pronounced decrease in CaM-kinase II activity in rats chronically injected with METH than in rats chronically injected with saline. Western blot analysis revealed that the amount of CaM-kinase II protein was not altered after a single METH injection or after chronic METH injections, compared with saline-treated controls. However, amounts of phosphorylated (Thr(286)) CaM-kinase II in the parietal cortex, striatum and SN/VTA were significantly decreased at 3 h after an acute METH injection compared with saline-treated controls. These results suggest that dephosphorylation of CaM-kinase II may contribute to the decreased enzyme activities induced by acute METH administration, and that chronic treatment with METH leads to an enhanced capacity of METH to decrease CaM-kinase II activity after an extended withdrawal period.     

Elevated D3 dopamine receptor mRNA in dopaminergic and dopaminoceptive regions of the rat brain in response to morphine

As opiates increase dopamine transmission, we measured the effects of morphine on dopamine-related genes using a real-time optic PCR assay that reliably detects small differences in mRNA in discrete brain regions. Tissue from dopaminoceptive and dopaminergic brain regions was collected from rats injected twice daily for 7 days with saline or increasing doses of morphine. Tissues were assayed for D1, D2 and D3 dopamine receptor mRNAs (D1R, D2R and D3R), as well as for mRNAs for tyrosine hydroxylase (TH) and the dopamine transporter (DAT). The neuron-associated mRNAs for SNAP-25 and synaptophysin, as well as the glial-associated mRNA for S100-beta and three 'housekeeping' mRNAs, were also measured. As reported previously by others, there was no alteration in D1R mRNA and a 25% decrease in D2R mRNA in the caudate-putamen, 2 h after the final morphine injection. Importantly, in the same RNA extracts, D3R mRNA showed significant increases of 85% in the caudate-putamen and 165% in the ventral midbrain, including the substantia nigra and ventral tegmental area. There were no other significant morphine effects. Mapping of brain regions in saline control rats agreed with previous studies, including showing the presence of low abundance TH mRNA and the absence of DAT mRNA in the caudate-putamen. The finding that chronic, intermittent injections of morphine caused an increase in D3R mRNA extends our understanding of the ability of D3R agonists to reduce the effects of morphine.     

Site of rewarding action of morphine in the mesolimbic system determined by intracranial electrical self-stimulation

Systemic treatment with morphine has been shown to facilitate intracranial electrical self-stimulation reward elicited from the ventral tegmental area (VTA) as was determined using a response rate-insensitive threshold measurement. In the present experiment graded doses of morphine were microinjected into the mesolimbic system to determine the site of this morphine action. Morphine injected into the nucleus accumbens did not affect the threshold and response rate of self-stimulation by electrodes in the VTA, while relatively high doses of morphine injected into the VTA produced a long-lasting decrease of the threshold of self-stimulation by electrodes in the nucleus accumbens. It is concluded that morphine can facilitate self-stimulation when injected into the VTA, and that a concerted action of morphine on multiple brain sites may be involved in the interaction of the drug with brain reward.     

Mapping of c-fos gene expression in the brain during morphine dependence and precipitated withdrawal, and phenotypic identification of the striatal neurons involved

The c-fos gene is expressed in the central nervous system in response to various neuronal stimuli. Using in situ hybridization, we examined the effects of chronic morphine treatment and withdrawal on c-fos mRNA in the rat brain, and particularly within identified striatal neurons. Morphine dependence was induced by subcutaneous implantation of two pellets of morphine for 6 days and withdrawal was precipitated by administration of naltrexone. Placebo animals and morphine-dependent rats showed a very weak c-fos mRNA expression in all the structures studied. Our study emphasized the spatial variations in c-fos mRNA expression, and also revealed a peak expression of c-fos mRNA at 1 h after naltrexone-precipitated withdrawal in the projection areas of dopaminergic neurons, noradrenergic neurons and in several regions expressing opiate receptors. Interestingly, morphine withdrawal induces c-fos mRNA expression in the two efferent populations of the striatum (i.e. striatonigral and striatopallidal neurons) both in the caudate putamen and nucleus accumbens. Moreover, the proportions of activated neurons during morphine withdrawal are different in the caudate putamen (mostly in striatopallidal neurons) and in the shell and core parts of the nucleus accumbens (mostly in striatonigral neurons). The activation of striatopallidal neurons suggests a predominant dopaminergic regulation on c-fos gene expression in the striatum during withdrawal. On the contrary, c-fos induction in striatonigral neurons during withdrawal seems to involve a more complex regulation like opioid-dopamine interactions via the mu opioid receptor and the D1 dopamine receptor coexpressed on this neuronal population or the implication of other neurotransmitter systems.