Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, USA.
Transl Psychiatry. 2022 Sep 8;12(1):374. doi: 10.1038/s41398-022-02135-1.
Opioid exposure is known to cause transcriptomic changes in the nucleus accumbens (NAc). However, no studies to date have investigated cell type-specific transcriptomic changes associated with volitional opioid taking. Here, we use single nucleus RNA sequencing (snRNAseq) to comprehensively characterize cell type-specific alterations of the NAc transcriptome in rats self-administering morphine. One cohort of male Brown Norway rats was injected with acute morphine (10 mg/kg, i.p.) or saline. A second cohort of rats was allowed to self-administer intravenous morphine (1.0 mg/kg/infusion) for 10 consecutive days. Each morphine-experienced rat was paired with a yoked saline control rat. snRNAseq libraries were generated from NAc punches and used to identify cell type-specific gene expression changes associated with volitional morphine taking. We identified 1106 differentially expressed genes (DEGs) in the acute morphine group, compared to 2453 DEGs in the morphine self-administration group, across 27 distinct cell clusters. Importantly, we identified 1329 DEGs that were specific to morphine self-administration. DEGs were identified in novel clusters of astrocytes, oligodendrocytes, and D1R- and D2R-expressing medium spiny neurons in the NAc. Cell type-specific DEGs included Rgs9, Celf5, Oprm1, and Pde10a. Upregulation of Rgs9 and Celf5 in D2R-expressing neurons was validated by RNAscope. Approximately 85% of all oligodendrocyte DEGs, nearly all of which were associated with morphine taking, were identified in two subtypes. Bioinformatic analyses identified cell type-specific upstream regulatory mechanisms of the observed transcriptome alterations and downstream signaling pathways, including both novel and previously identified molecular pathways. These findings show that volitional morphine taking is associated with distinct cell type-specific transcriptomic changes in the rat NAc and highlight specific striatal cell populations and novel molecular substrates that could be targeted to reduce compulsive opioid taking.
阿片类物质暴露已知会导致伏隔核（NAc）的转录组变化。然而，迄今为止尚无研究调查与自愿性阿片类物质摄入相关的特定于细胞类型的转录组变化。在这里，我们使用单个核 RNA 测序（snRNAseq）全面描述大鼠自行给予吗啡时 NAc 转录组的细胞类型特异性改变。一组雄性棕色挪威大鼠接受急性吗啡（10mg/kg，ip）或生理盐水注射。第二组大鼠被允许连续 10 天自行静脉注射吗啡（1.0mg/kg/输注）。每只经历过吗啡的大鼠都与一只配对的盐水对照大鼠配对。从 NAc 穿刺物中生成 snRNAseq 文库，并用于鉴定与自愿性吗啡摄入相关的细胞类型特异性基因表达变化。与急性吗啡组相比，我们在吗啡自我给药组中鉴定出 1106 个差异表达基因（DEG），在 27 个不同的细胞簇中鉴定出 2453 个 DEG。重要的是，我们鉴定出 1329 个特定于吗啡自我给药的 DEG。在 NAc 中的新型星形胶质细胞、少突胶质细胞和 D1R 和 D2R 表达的中型多棘神经元簇中鉴定出 DEG。细胞类型特异性 DEG 包括 Rgs9、Celf5、Oprm1 和 Pde10a。通过 RNAscope 验证了 D2R 表达神经元中 Rgs9 和 Celf5 的上调。与吗啡摄入相关的大约 85%的所有少突胶质细胞 DEG 都在两个亚型中鉴定出来。生物信息学分析确定了观察到的转录组改变的特定于细胞类型的上游调节机制和下游信号通路，包括新的和以前确定的分子途径。这些发现表明，自愿性吗啡摄入与大鼠 NAc 中特定于细胞类型的转录组变化有关，并突出了特定的纹状体细胞群和新的分子底物，这些可能是减少强制性阿片类物质摄入的目标。
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