健康与遗传心理学研究室知识库

研究目的：用药相关线索诱发的强烈渴求是驱动复吸的主要原因之一，并随着戒断时间的延长，渴求程度不断增强从而产生持续的觅药行为，即潜伏渴求。纹状体的高线索反应性是介导潜伏渴求的关键因素，与钙离子的跨膜转运有关。LTCCs 作为胞内钙离子的重要来源，能够通过信号转导途径长期调节神经元功能。阐明LTCCs 调控潜伏渴求的内在机制及亚型特异性，不仅具有重要的理论意义，还有可能为干预和治疗药物成瘾的复吸提供新的靶点。

研究方案：本研究采用近灵长类动物树鼩作为实验对象，进行如下实验：1）创建树鼩药物成瘾模型；2）明确树鼩可卡因潜伏渴求过程的时间特性，同时衡量其觅/用药动机水平；3）明确介导可卡因潜伏渴求的关键脑区，并阐明LTCCs调控作用及Cav1.2 和Cav1.3 参与这一过程的亚型特异性；4）探索LTCCs 调控潜伏渴求的内在分子机制。

研究结果：1）创建了树鼩吗啡CPP/CPA 及可卡因SA 模型；2）戒断第45天，树鼩的潜伏渴求行为最明显，且觅药动机最强；3）腹腔脑室以及NAc 注射LTCCs 拮抗剂verapamil 均能够抑制可卡因潜伏渴求行为；4）NAc 内的Cav1.2，而非Cav1.3，其蛋白表达水平随戒断时间的延长而增加。并且，利用shRNA 敲减Cav1.2 能够显著减少戒断第45 天的觅药行为，而利用shRNA 敲减Cav1.3 则对潜伏渴求行为没有影响；5）NAc 显微注射多巴胺D1 受体（D1R）拮抗剂SCH23390 不仅能够显著降低觅药行为，而且逆转了Cav1.2 的高蛋白表达水平。

实验结论：本研究阐明NAc 的Cav1.2 通过与D1R 间的信号转导途径调控可卡因潜伏渴求行为，提示LTCCs 可能是介导纹状体神经元高线索反应性的关键分子。此外，树鼩具有与灵长类更相近的神经功能，利于进行动物-人的转化实验研究。因此，临床药物LTCCs 拮抗剂verapamil 具有潜在的干预复吸的效果，且Cav1.2 可能是特异性治疗药物成瘾复吸的关键靶分子。

Objectives：Cue-induced craving is one of the major cause of relapse. This craving progressively intensifies during withdrawal from cocaine leading to a persistent seeking behavior, a phenomenon termed incubation of craving. The expression of incubation is critically mediated by the excitatory response of neurons in nucleus accumbens (NAc), and the intracellular Ca2+ plays an important role during this process. As one of the major resources of intracellular Ca2+, L-type calcium channels (LTCCs) can regulate long-term neuronal function through various signaling pathways. Hence, illumination of the subtypes specificity and molecular mechanism of LTCCs regulating incubation could not only have great theoretical value, but also provide a potential target for therapeutic intervention of relapse.

Methods: In this study, tree shrews, which is close to primates according to the homology of gene, were used as the experimental animals to perform the following experiments: 1) Establish addiction models in tree shrews, 2) Explore the time course of craving during different periods of withdrawal and identify the level of motivation for cocaine, 3) Explore the role of LTCCs on seeking behavior, especially identify the key brain area and the specific functions of different subtypes, 4) Explore the possible mechanism of LTCCs participating in incubation of craving.

Results: 1) Morphine CPP/CPA and cocaine SA models were established successfully in tree shrews. 2) After cocaine SA training, the seeking behavior and motivation were higher on withdrawal day 45 (WD45) compared with on withdrawal day 1 (WD1). 3) Intraperitoneal, intracerebroventricular or intra-NAc injection with LTCCs antagonist verapamil all could reduce seeking behavior after long-term withdrawal. 4) The expression of Cav1.2, but not Cav1.3, in the NAc was higher after seeking test on WD45 than on WD1. Furthermore, knockdown of Cav1.2 in the NAc via pAV-Cav1.2-shRNA decreased the seeking behavior on WD45, whereas knockdown of Cav1.3 had no such effect. 5) Intra-NAc injection with dopamine D1 receptors (D1R) antagonist SCH23390 attenuated the seeking behavior, meanwhile reversed the expression of Cav1.2.

Conclusions: The study indicated that Cav1.2 in the NAc regulated the incubation of craving through the activation of D1R. This finding implied that LTCCs might be the key molecular increasing the excitatory ability of neurons in the NAc. Additionally, the application of tree shrews, which have highly homologous neural functions compared with primates, could promote the translational research from animal to human. Therefore, LTCCs antagonist verapamil might be a potential candidate for relapse treatment, and Cav1.2 might be the key molecular target for intervention of relapse.