Elucidating Ih Biophysical Epigenetic Modifications in VTA Dopaminergic Neurons after Contingent and Non-Contingent Cocaine Administration

摘要 腹侧被盖区(VTA)是参与奖赏和强化的中枢神经系统的关键区域 天然物质和毒品，如可卡因。超极化激活阳离子电流(Ih) 是多巴胺(DA)能神经元基本固有特性的关键参与者 VTA。携带Ih的离子通道由HCN亚基组成，主要是 VTA。可卡因敏化(CS)后，由于药物暴露而引起的Ih改变。 Ih的这种变化可能是中枢奖赏/强化的一种常见的生理机制 导致上瘾的途径。组蛋白去乙酰化等表观遗传机制 对慢性用药后发生的一些关键的神经元变化负责。 本课题将研究Ih功能在CS发育过程中的表观遗传调控。 和间歇访问自我管理(INTA)模型。在我们看来，INTA更好 模拟人类的药物消耗。具体目标将包括：1)调查VTA CS、INTA和组蛋白脱乙酰酶抑制剂(HDACi)后的表观基因组图谱；2) CS、INTA和HDACi后VTA DA神经元Ih的电生理检测 测量CS、INTA和HDACi后VTA内HCN2亚基的变化；4)调查 靶向HDAC2的活体shRNA改变CS、INTA和VTA DA的性质 神经元。检查可卡因诱导的VTA的表观遗传学变化可以提供关键 关于成瘾发展过程中发生的神经适应的信息。反转 在这些表观遗传修饰中，通过抑制组蛋白脱乙酰酶可能提供了可能 治疗性药理干预的途径。

ABSTRACT The ventral tegmental area (VTA) is a key CNS region involved in the reward and reinforcement of natural substances and drugs, such as cocaine. Hyperpolarization-activated cation current (Ih) is a key participant in the fundamental intrinsic properties of dopaminergic (DA) neurons of the VTA. The ion channels that carry Ih are comprised of HCN subunits, predominantly the HCN2 in the VTA. Alteration of Ih due to drug exposure has been shown after cocaine sensitization (CS). This change in Ih may be a common physiological mechanism in central reward/reinforcement pathways that contributes to addiction. Epigenetic mechanisms like histone deacetylation are responsible for some crucial neuronal changes that occur following chronic drug administration. This project will study the epigenetic regulation of the Ih function during the development of CS and on the Intermittent access self-administration (IntA) model. The IntA in our opinion better simulates human drug consumption. The specific aims will include: 1) To investigate the VTA epigenomic profile after CS, IntA and Histone Deacetylase inhibitor (HDACi); 2) Electrophysiological examination of Ih in VTA DA neurons after CS, IntA and HDACi; 3) To measure changes in HCN2 subunits in the VTA after CS, IntA and HDACi; 4) To investigate if in vivo shRNA targeting HDAC2 alters the development of CS, IntA and Ih properties of VTA DA neurons. Examination of cocaine-induced epigenetic changes in the VTA can provide key information about neuroadaptations that occur during the development of addiction. The reversal of these epigenetic modifications by histone deacetylase inhibition might provide possible avenues for therapeutic pharmacological intervention.