Coles Cassandre, Lasek Amy W
Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA.
Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA.
Neurosci Insights. 2021 Apr 16;16:26331055211009850. doi: 10.1177/26331055211009850. eCollection 2021.
Alcohol use disorder is associated with pathophysiological changes in the dopaminergic system. Orthodenticle homeobox 2 (OTX2) is a transcription factor important for the development of dopaminergic neurons residing in the ventral tegmental area (VTA), a critical region of the brain involved in drug reinforcement. Previous studies have demonstrated that ethanol exposure during embryonic development reduces mRNA levels in the central nervous system. We hypothesized that levels of OTX2 would be altered by binge-like ethanol consumption in adult animals. To test this, mRNA and protein levels in the mouse VTA were measured by quantitative real-time PCR and western blotting, respectively, after mice drank ethanol for 4 days in a procedure that elicits binge levels of ethanol consumption (drinking in the dark). Expression of known and putative OTX2 transcriptional target genes (, , and ) were also measured in the VTA after ethanol drinking. mRNA and protein levels were elevated in the VTA 24 hours after the fourth drinking session and there was a corresponding increase in the expression of transcript. Interestingly, transcript was elevated in the VTA immediately after the fourth drinking session but returned to control levels 24 hours later. We next investigated if viral-mediated reduction of in the mouse VTA would alter ethanol or sucrose intake. Lentiviral vectors expressing a shRNA targeting or a control shRNA were injected into the VTA and mice were tested in the drinking in the dark protocol for ethanol and sucrose drinking. Reducing levels of OTX2 in the VTA did not alter ethanol or sucrose consumption. One limitation is that the extent of OTX2 reduction may not have been sufficient. Although OTX2 in the VTA may not play a role in binge-like drinking in adult mice, OTX2 could contribute to ethanol-induced transcriptional changes in this region.
酒精使用障碍与多巴胺能系统的病理生理变化有关。正齿同源盒2（OTX2）是一种转录因子，对腹侧被盖区（VTA）中多巴胺能神经元的发育很重要，VTA是大脑中参与药物强化的关键区域。先前的研究表明，胚胎发育期间接触乙醇会降低中枢神经系统中的mRNA水平。我们假设成年动物暴饮样乙醇消费会改变OTX2的水平。为了验证这一点，在小鼠通过一种引发暴饮水平乙醇消费的程序（在黑暗中饮用）饮用乙醇4天后，分别通过定量实时PCR和蛋白质印迹法测量小鼠VTA中的mRNA和蛋白质水平。在饮用乙醇后，还测量了VTA中已知和假定的OTX2转录靶基因（、和）的表达。在第四次饮用后24小时，VTA中的mRNA和蛋白质水平升高，并且转录物的表达相应增加。有趣的是，在第四次饮用后立即VTA中的转录物升高，但在24小时后恢复到对照水平。接下来，我们研究了病毒介导的小鼠VTA中减少是否会改变乙醇或蔗糖的摄入量。将表达靶向的短发夹RNA或对照短发夹RNA的慢病毒载体注射到VTA中，并在黑暗中饮用乙醇和蔗糖的方案中对小鼠进行测试。降低VTA中OTX2的水平不会改变乙醇或蔗糖的消耗。一个局限性是OTX2减少的程度可能不够。虽然VTA中的OTX2可能在成年小鼠的暴饮样饮酒中不起作用，但OTX2可能促成该区域中乙醇诱导的转录变化。
