Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois.
Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois.
Biol Psychiatry. 2024 Feb 1;95(3):275-285. doi: 10.1016/j.biopsych.2023.07.018. Epub 2023 Aug 9.
The ventral tegmental area (VTA) is a dopaminergic brain area that is critical in the development and maintenance of addiction. During withdrawal from chronic ethanol exposure, the response of VTA neurons to GABA (gamma-aminobutyric acid) is reduced through an epigenetically regulated mechanism. In the current study, a whole-genome transcriptomic approach was used to investigate the underlying molecular mechanism of GABA hyposensitivity in the VTA during withdrawal after chronic ethanol exposure.
We performed RNA sequencing of the VTA of Sprague Dawley male rats withdrawn for 24 hours from a chronic ethanol diet as well as sequencing of the VTA of control rats fed the Lieber-DeCarli diet. RNA sequencing data were analyzed using weighted gene coexpression network analysis to identify modules that contained coexpressed genes. Validation was performed with quantitative polymerase chain reaction, gas chromatography-mass spectrometry, and electrophysiological assays.
Pathway and network analysis of weighted gene coexpression network analysis module 1 revealed a significant downregulation of genes associated with the cholesterol synthesis pathway. Consistent with this association, VTA cholesterol levels were significantly decreased during withdrawal. Chromatin immunoprecipitation indicated a decrease in levels of acetylated H3K27 at the transcriptional control regions of these genes. Electrophysiological studies in VTA slices demonstrated that GABA hyposensitivity during withdrawal was normalized by addition of exogenous cholesterol. In addition, inhibition of cholesterol synthesis produced GABA hyposensitivity, which was reversed by adding exogenous cholesterol to VTA slices.
These results suggest that decreased expression of cholesterol synthesis genes may regulate GABA hyposensitivity of VTA neurons during alcohol withdrawal. Increasing cholesterol levels in the brain may be a novel avenue for therapeutic intervention to reverse detrimental effects of chronic alcohol exposure.
腹侧被盖区（VTA）是一个多巴胺能脑区，在成瘾的发展和维持中至关重要。在慢性乙醇暴露戒断期间，通过表观遗传调控机制，VTA 神经元对 GABA（γ-氨基丁酸）的反应降低。在目前的研究中，采用全基因组转录组学方法研究慢性乙醇暴露后戒断期间 VTA 中 GABA 低敏性的潜在分子机制。
我们对慢性乙醇饮食戒断 24 小时的 Sprague Dawley 雄性大鼠的 VTA 进行了 RNA 测序，以及 Lieber-DeCarli 饮食喂养的对照大鼠的 VTA 测序。使用加权基因共表达网络分析对 RNA 测序数据进行分析，以识别包含共表达基因的模块。通过定量聚合酶链反应、气相色谱-质谱联用和电生理测定进行验证。
加权基因共表达网络分析模块 1 的通路和网络分析显示，与胆固醇合成途径相关的基因显著下调。与这种关联一致，VTA 胆固醇水平在戒断期间显著降低。染色质免疫沉淀表明，这些基因的转录控制区乙酰化 H3K27 水平降低。VTA 切片的电生理研究表明，戒断期间 GABA 低敏性通过添加外源性胆固醇得到正常化。此外，胆固醇合成抑制产生 GABA 低敏性，而向 VTA 切片添加外源性胆固醇可逆转这种低敏性。
这些结果表明，胆固醇合成基因的表达降低可能调节酒精戒断期间 VTA 神经元的 GABA 低敏性。增加大脑中的胆固醇水平可能是一种新的治疗干预途径，可逆转慢性酒精暴露的有害影响。
