D4R在METH诱导小鼠成瘾中的调控作用研究

The regulatory role of D4R in methamphetamine-induced addiction in mice

目的探讨脑内多巴胺D4受体(dopamine D4 receptor,D4R)对小鼠甲基苯丙胺(methamphetaine,METH)成瘾行为学和分子生物学的影响,综合分析D4R在小鼠METH成瘾过程中的调控作用。方法首先将C57BL/6小鼠随机分为生理盐水组(S组)、METH对照组(M组)和D4R配体干预组进行条件性位置偏爱(conditioned place preference,CPP)实验,分析D4R配体对METH成瘾小鼠CPP表达的影响;CPP测试结束后立即剥离所有小鼠的脑核团组织(前额叶皮质、伏隔核、海马和中脑腹侧被盖区),提取RNA进行实时荧光定量PCR检测,分析METH成瘾小鼠各脑区D4R基因表达的差异性。结果D4R配体对小鼠测试期总活动量无影响,但可以显著促进实验小鼠CPP的表达;METH成瘾小鼠各脑区内D4R mRNA表达水平与S组相比显著增加,D4R配体干预组实验小鼠各脑区D4R mRNA表达水平与M组相比显著降低。结论本研究发现METH可导致成瘾小鼠相关脑区核团内D4R表达水平代偿性升高,D4R在METH成瘾过程中发挥重要作用。D4R激动剂和拮抗剂均可对抗METH的作用,使小鼠各脑区D4R表达水平降低,这些脑区内D4R水平的下降,可能会增强相关通路的兴奋性,导致METH成瘾小鼠CPP表达增强。

Objective To explore the effects of D4R on the behavior and molecular changes in METH-addicted mice,and comprehensively analyze the regulatory role of D4R in METH addiction in mice.Methods C57BL/6 mice were randomly divided into the saline group(Group S),the METH control group(Group M),and the D4R ligand intervention group.Conditioned place preference(CPP)test was then conducted to investigate the effects of D4R ligand on the CPP expression in METH-addicted mice.The prefrontal cortex,nucleus accumbens,hippocampus,and the ventral tegmental area of midbrain of all mice were stripped immediately after the CPP test,and the RNA was then extracted for real-time fluorescence Q-PCR detection to explore the differential expression of D4R-related genes in the various brain regions of METH-addicted mice.Results The D4R ligand had no effect on the locomotor activity of all mice during the testing period,but significantly promoted the expression of CPP.The expression levels of D4R mRNA in all four brain regions were significantly increased after METH exposure,whereas D4R ligand attenuated the upregulation of D4R mRNA levels.Conclusion METH can lead to a compensatory increase in the D4R expression levels in the relevant brain regions of addicted mice,and D4R plays an important role in METH addiction.Both D4R agonist and antagonist can antagonize the effects of METH and reduce the levels of D4R in four brain regions of mice,indicating that the D4R in the prefrontal cortex,nucleus accumbens,hippocampus and the ventral tegmental area of midbrain plays an important role in the regulation of METH addiction.The decrease of D4R levels in these brain regions may activate the relevant signal pathways,leading to an increased CPP expression in METH-addicted mice.