【作者】 于鲁璐；

【导师】 王学义；

【作者基本信息】 河北医科大学 ， 精神病与精神卫生学， 2008， 硕士

【摘要】 目的:甲基苯丙胺(methamphetamine, METH)是一种常用的成瘾药物,具有强烈的中枢兴奋作用。近年来,我国滥用METH人数持续上升。随着这类药物的长期滥用,其精神依赖性和严重的毒副作用也日益突出。这不仅给滥用者自身带来危害,也造成了严重的社会问题。新的理论表明,药物成瘾是一种慢性复发性脑病,反复使用成瘾药物可以形成异常持久的药物奖赏性记忆,作为一种异常的学习记忆,它与正常记忆的相似之处在于,也需要经过一个信息获得和巩固的过程才能形成较为稳定的记忆。而且当该记忆被再次唤起后,会处于一种不稳定而易被破坏的状态,其再次稳定仍需要一个类似于巩固的过程,因此,通过干预药物奖赏记忆的巩固过程可以破坏记忆的形成,而对记忆再巩固过程的干预,则可以改变或消除原有记忆。大麻素CB1受体是用于治疗药物成瘾的一个新的靶点,内源性大麻素(endocannabinoids)和CB1受体广泛分布于记忆相关脑区,参与记忆的调节。已有很多研究将CB1受体作为新的靶点用于研究空间记忆和恐怖记忆,不同的记忆类型其研究结果也存在差异。在成瘾记忆中,尚缺乏与CB1受体有关的系统研究。条件性位置偏爱(conditioned place preference, CPP)是广泛应用于评价药物奖赏效应的实验方法,近年来也被用于药物成瘾记忆的研究,药物与环境之间的反复关联使动物产生长期的行为改变,反映了奖赏控制的学习过程。METH-CPP使动物对与METH相关的特定环境产生偏爱,这一行为模型模拟了METH应用-联想记忆,特定环境线索(条件性刺激)与METH所产生的欣快感(非条件性刺激)反复关联,激发了动物在无药状态选择药物相关环境的动机行为。本实验的目的是用CB1受体拮抗剂利莫那班(rimonabant)对CPP模型奖赏记忆形成的不同阶段进行干预,观察其在METH奖赏记忆中的作用。方法:1、小鼠6组(n=6),分别用生理盐水(NS)和METH(0.5mg/kg或2mg/kg,i.p)训练CPP,训练时间分别为20min或60min,训练8天后进行CPP测试,观察在不同条件下METH-CPP的形成是否有显著性差异,确定METH-CPP形成的最佳条件。2、小鼠3组(n=10)训练METH-CPP(2mg/kg, 20min,i.p),并在每次训练后立即分别给予不同剂量的利莫那班(0mg/kg,1.0mg/kg和3.0mg/kg,i.p)观察利莫那班对METH-CPP形成的影响。3、小鼠3组(n=8),训练METH-CPP(2mg/kg,20min,i.p),在CPP测试前30min分别给予不同剂量的利莫那班(0mg/kg,1.0mg/kg和3.0mg/kg),观察利莫那班对METH-CPP的影响。并在测试后24小时,7天和14天时重复测定CPP值,并于第15天给予METH(0.5mg/kg,i.p),观察METH-CPP能否重现;4、小鼠3组(n=9),训练METH-CPP(2mg/kg, 20min,i.p),在CPP测试结束后立即分别给予不同剂量的利莫那班(0mg/kg,1.0mg/kg和3.0mg/kg)并在测试后24小时,7天和14天时重复测定CPP值,并于第15天给予METH(0.5mg/kg,i.p),观察METH-CPP能否重现;5、小鼠3组(n=10),训练METH-CPP(2mg/kg,20min,i.p),CPP形成后使其消退,测试消退后第二天给予METH(0.5mg/kg,i.p),观察METH-CPP能否复现;并在点燃前30min给予不同剂量的利莫那班( 0mg/kg , 1.0mg/kg和3.0mg/kg),观察其对点燃的影响。结果:1、与生理盐水对照组相比,4种不同训练条件下的小鼠均形成CPP;2、与空白对照组相比,利莫那班1.0mg/kg组和3.0mg/kg组均未形成CPP,提示利莫那班破坏了METH奖赏记忆的巩固过程;3、与空白对照组相比,利莫那班3mg/kg组小鼠未能表达显著的CPP,提示利莫那班阻断了奖赏记忆的唤起,抑制了小鼠METH-CPP的表达;4、与空白对照组相比,CPP测试后立即给予3mg/kg的利莫那班,可以破坏已经形成的CPP,而未经唤起的小鼠其CPP持续存在,提示利莫那班破坏了奖赏记忆的再巩固过程,且这一作用是唤起依赖的;5、与空白对照组相比,3mg/kg的利莫那班可以抑制METH(0.5mg/kg)诱导的CPP消退后复现。结论:昆明小鼠可以形成显著的METH-CPP,大麻素CB1受体拮抗剂利莫那班可以破坏METH奖赏记忆的巩固、唤起和再巩固过程;小剂量的METH可以使小鼠已经消退的CPP行为重现,利莫那班可以抑制METH的这一点燃作用。更多还原

【Abstract】 Objectives: Methamphetamine (METH) is a commonly used, addictive drug, and a powerful stimulant that dramatically affects the central nervous system. METH users continually increased in our country in recent years. And its psychological dependence and serious adverse effects have been outstanding day by day. METH abuse not only brings about health problems to drug users, but also results in serious social problems. Drug addiction is a chronic, relapsing brain disorder. Repeated drug use associated with contexts lead to form an abnormally persistent rewarding memory. Similar to normal learning and memory, drug memory achieve a stable and relatively permanent state via an acquisition and consolidation process to form long term memory. However, they become labile when they are reactivated and must be reconsolidated to achieve a stable state again. Thus, some treatments could be used to block acquisition of memory via interfere with memory consolidation and impair original memory through disrupting memory reconsolidation. Cannabinoid CB1 receptor is a new target for drug addiction therapy. Endocannabinoids and CB1 receptor are widely distributed in memory-related brain regions, participated in memory modulation. There have been many studies to investigate the role of CB1 receptor in spatial or fear memory. Conclusions were not consistent since the types of memory were different. Drug-related memory studies using CB1 receptor were concentrated on extinction learning, which indicated that cannabinoid CB1 receptor blocked extinction process and inhibitory extinction behaviors. Conditioned place preference (CPP) paradigm has been widely used to evaluate the rewarding effect. Repeated association of drugs use with contexts predicting drug availability leads to long-lasting behavioral responses that reflect reward-controlled learning. METH-induced conditioned place preference (CPP), the preference for the specific place containing the METH conditioned cues over a natural control place, has been used as a behavioral paradigm for mimicking the METH use-associated memory. In this conditioning paradigm, repeated association of the specific environmental cues (conditioned stimulus) with METH-induced subjective euphoria (unconditioned stimulus) has been suggested to motivate animals’later approaching behavior toward the euphoria-linked environment at a drug-free status. In the present study, we used the conditioned place preference (CPP) paradigm in order to investigate the role of cannabinoid CB1 receptor antagonist in the drug-related memory.Methods: 1, Mice were divided into 6 groups which were saline-20min, saline-60min, 0.5mg/kg-20min, 0.5mg/kg-60min, 2mg/kg-20min and 2mg/kg-60min by different training paradigms. The acquisition of CPP was observed after training. The dose of METH and confining time were then identified and applied to subsequent experiments. 2, Mice were divided into 3 groups to be trained for METH CPP(2mg/kg, 20min, i.p)and were given intra-peritoneal injections of different doses of rimonabant(0, 1.0mg/kg and 3.0mg/kg) immediately after each conditioning session. After 8 consecutive sessions, mice were tested for CPP. 3, Mice were divided into 3 groups to be trained for METH CPP(2mg/kg, 20min, i.p). Administrations of different doses of rimonabant (0mg/kg, 1.0mg/kg and 3.0 mg/kg) were given 30min before place preference testing. Retesting of METH CPP was done 24 hours, 7 days or 14 days after rimonabant administration. On the 15th day, mice were injected with a priming dose of METH (0.5mg/kg) and were tested to see whether place preference was reinstated. 4, Mice were divided into 3 groups to be trained for METH CPP(2mg/kg, 20min, i.p). Administrations of different doses of rimonabant (0mg/kg, 1.0mg/kg and 3.0 mg/kg) were given immediately after place preference testing. Retesting of METH CPP was done 24 hours, 7 days or 14 days after rimonabant administration. On the 15th day, mice were injected with a priming dose of METH (0.5mg/kg) and were tested to see whether place preference was reinstated. 5, Mice were divided into 3 groups to be trained for METH CPP(2mg/kg, 20min, i.p). After 8 consecutive sessions and tested for METH CPP, mice were not given any treatment and were retest every 3 days. One day after the determination of place preference extinction, mice were injected with a priming dose of METH (0.5mg/kg) and were tested to see whether place preference was reinstated. Different doses of rimonabant (0mg/kg, 1.0mg/kg and 3.0 mg/kg) were administered 30 minutes prior to the priming injection of METH.Results: 1, Compared with saline groups, 4 METH groups with different training paradigms all expressed a METH CPP and no significant difference was found between any two groups. 2, Compared with vehicle group, post-training administration of 1mg/kg and 3mg/kg rimonabant blocked the acquisition of METH CPP, suggesting rimonabant disrupted consolidation of METH rewarding memory. 3, Compared with vehicle group, pre-test administration of 3mg/kg rimonabant inhibited CPP expression while other two groups expressed significant CPP, suggesting rimonabant blocked retrieval of METH rewarding memory. The effect lasted for at least 1 week. 4, Compared with vehicle group, 24h after post-testing administration of different doses of rimonabant, mice in 3mg/kg group which expressed significant CPP in the first place preference testing failed to express CPP the next day and in subsequent tests. However, mice in groups without retrieval expressed CPP persistently, suggesting the effect of rimonabant on memory reconsolidation was retrieval-dependent. 5, Compared with vehicle group, a dose of 0.5mgkg METH failed to induce the reinstatement of CPP in the group of 3mg/kg rimonabant, suggesting rimonabant could inhibit reinstatement of METH CPP.Conclusion: The present study indicated that mice expressed significant CPP produced by METH. Cannabinoid CB1 receptor antagonist disrupted consolidation, retrieval and reconsolidation of METH rewarding memory. A priming dose of METH induced reinstatement of CPP which could be attenuated by rimonabant.更多还原