A single-cell atlas of gene expression and chromatin accessibility changes associated with cocaine addiction in the rat amygdala (snATAC-Seq Multiome)

The amygdala plays a key role in the negative emotional states associated with the relapse to drug seeking behavior. Neuroanatomical and functional observations have uncovered the role of discrete amygdala subregions in different aspects of these negative affective states. However, the underlying transcriptional regulatory programs driving the function of distinct amygdala cell types remains unknown. We generated an atlas of single nucleus gene expression and chromatin accessibility in the amygdala of rats with low and high cocaine addiction-like behaviors after prolonged abstinence from extended access to cocaine intravenous self-administration. We identified thousands of cell type-specific differentially expressed genes, suggesting that negative affective states are associated with cell type-specific mechanisms which are enriched for molecular pathways, including energy metabolism and GABAergic synapses in excitatory and somatostatin neurons. We demonstrate that higher addiction severity is linked to excessive GABAergic inhibition and, using pharmacological inhibition, we find that addiction-like phenotypes are regulated by the metabolite methylglyoxal which is an agonist at GABA-A receptors. By analyzing differences in chromatin accessibility, we predict upstream transcriptional regulators associated with addiction-like behavior and find discordant regulation of key transcription factors among distinct cell populations. Overall, we provide a comprehensive characterization of cell type-specific transcriptional changes in the amygdala during protracted abstinence and use these insights to identify a novel target for pharmacological intervention.杏仁核（amygdala）在与复吸觅药行为相关的负性情绪状态中发挥关键作用。神经解剖学与功能学观测已揭示，不同杏仁核亚区在这类负性情绪状态的不同维度中承担特定功能。然而，调控不同杏仁核细胞类型功能的潜在转录调控程序仍未明确。 本研究针对经长期可卡因静脉自身给药暴露、并在戒断较长时间后，表现出高低不同可卡因成瘾样行为的大鼠，构建了其杏仁核内的单细胞核基因表达与染色质可及性图谱。我们鉴定出数千个细胞类型特异性差异表达基因，提示负性情绪状态与细胞类型特异性调控机制相关——这类机制在兴奋性神经元与生长抑素（somatostatin）神经元中，显著富集能量代谢、γ-氨基丁酸能突触（GABAergic synapses）等分子通路。 本研究证实，成瘾严重程度与过度的γ-氨基丁酸能抑制作用相关；同时通过药理学抑制实验发现，成瘾样表型受代谢产物甲基乙二醛（methylglyoxal）调控——该物质是GABA_A受体（GABA-A receptors）的激动剂。通过分析染色质可及性差异，我们预测了与成瘾样行为相关的上游转录调控因子，并发现不同细胞群中关键转录因子的调控模式存在不一致性。 综上，本研究全面刻画了长期戒断期间杏仁核内细胞类型特异性的转录组变化，并基于这些发现确定了一个全新的药理学干预靶点。