Measuring and Manipulating Reward Circuit Plasticity in Opiate Addition Models

鸦片成瘾是一个主要的健康问题，其慢性复发的性质可能是最阴险的 纵横比。在复发之前，吸毒者在接触毒品或与毒品有关的时候通常会经历强烈的渴望 刺激物。对抗成瘾的关键一步是了解神经化学和细胞 在戒毒后很长一段时间内恢复吸毒的机制。原子核 伏隔(NAC)是哺乳动物大脑中成瘾药物的一个关键靶点，并提供了背后的动力 看药行为。尽管药物诱导的NAc AMPA型谷氨酸受体(AMPAs)的可塑性 在精神刺激剂复发、阿片类药物诱导的时间和解剖动力学方面进行了广泛的研究 可塑性以及这些适应如何起到促进复发的作用尚不清楚。在这里，我研究了吗啡诱导的 皮质纹状体脑回路中突触强度和谷氨酸相关可塑性的适应性 将全细胞电生理方法与病毒介导的光敏Opsins表达相结合 (光遗传学)，以及可操作的给药模型中的荧光报告小鼠。来自我们实验室的试点数据 提示戒断后NAC壳区MSN谷氨酸能突触强度增强 (10-14天)临时和非临时吗啡注射。 在K99目标中，我建议勾勒出发展和持续变化的时间进程 NAC培养基亚群的突触强度、谷氨酸受体信号和亚基组成 含有多巴胺d1-(d1-msn)或d2-(d2-msn)受体亚型的多刺神经元(MSN) 一种成瘾的扩展通路操作模型。接下来，我建议选择性地激活视紫红质2通道- 利用直接传递到NAC的光刺激将皮质或杏仁传入表达到MSN上 评估特定途径的可塑性改变。K99阶段的训练将在Dr。 马克·托马斯是一位测量奖赏回路中谷氨酸能突触功能的专家，他的实验室已经 最近结合了光遗传学工具进行体外和体内研究。我们已经招募了额外的人员 Tim Ebner博士(光遗传学/导师)、Antonello Bonci博士(光遗传学和行为学)和 大卫·赛尔夫(小鼠药物自我管理)是我的顾问委员会的一部分。 通过神经网络的电生理学和光遗传调制方面的培训，我在 K99期间，我将利用这些技术进一步确定持久性阿片剂诱导的功能作用 可塑性在情境、线索和药物诱导的复发中发挥作用。利用体内光遗传刺激来 去增强NAC MSN的皮质和/或边缘传入，我预测恢复“基础”神经传递 在复发测试之前，使用已建立的长期抑郁方案将防止随后返回到 寻求鸦片类药物。最后，我将使用最近展示的一种新的模型成瘾模型来促进强迫症 在一组小鼠中寻找药物以探索兴奋性和抑制性神经传递的变化 内侧前额叶皮质和背侧纹状体的神经元，这两个大脑区域通常 在鸦片可塑性研究中被忽视。这些实验将为鸦片类药物的研究做出重大贡献 成瘾文献以及减轻复发的潜在药物治疗靶点。

Opiate addiction is a major health concern, and its chronic relapsing nature is perhaps its most insidious aspect. Preceding relapse, addicts often experience intense craving when exposed to drug or drug-associated stimuli. An essential step in confronting addiction is understanding the neurochemical and cellular mechanisms responsible for the resumption of drug use long after cessation of drug use. The nucleus accumbens (NAc) is a key target of addictive drugs in the mammalian brain and provides a motive force behind drug-seeing behavior. Although drug-induced plasticity in NAc AMPA-type glutamate receptors (AMPARs) has been studied extensively in psychostimulant relapse, the temporal and anatomical dynamics of opiate-induced plasticity and how these adaptations function to promote relapse is unknown. Here, I examine morphine-induced adaptations in synaptic strength and glutamate-related plasticity within corticostriatal brain circuits by combining whole-cell electrophysiological approaches with viral-mediated expression of light sensitive opsins (optogenetics), and fluorescent reporter mice in operant models of drug-administration. Pilot data from our lab indicate that MSN glutamatergic synaptic strength is potentiated in the NAc shell region following abstinence (10-14 days) from both contingent and non-contingent morphine administration. In the K99 Aims, I propose to delineate the time course of development and persistence of changes in synaptic strength, glutamate receptor signaling and subunit composition in subpopulations of NAc medium spiny neurons (MSNs) containing either the dopamine D1-(D1-MSN) or D2-(D2-MSN) receptor subtype using an extended-access operant model of addiction. Next, I propose to selectively activate channelrhodopsin2- expressing cortical or amygdalar afferents onto MSNs using optical stimulation delivered directly to the NAc to evaluate pathway-specific alterations in plasticity. Training in the K99 phase will be under the guidance of Dr. Mark Thomas, an expert in measuring glutamatergic synaptic function in reward circuits, whose lab has recently incorporated the use of optogenetics tools for in vitro and in vivo study. We have recruited additional expertise from Drs. Tim Ebner (optogenetics/ mentorship), Antonello Bonci (optogenetics and behavior) and David Self (mouse drug self-administration) as part of my advisory committee. With the training in electrophysiology and optogenetic modulation of neural networks I receive during the K99 period, I will employ these techniques to further determine the functional role persistent opiate-induced plasticity plays in context-, cue-, and drug-induced relapse. Using in vivo optogenetic stimulation to depotentiate cortical and/or limbic afferents onto NAc MSNs, I predict that restoring "basal" neurotransmission prior to relapse testing using an established long-term depression protocol will prevent a subsequent return to opiate-seeking. Finally, I will use a novel model addiction model recently shown to promote compulsive-like drug-seeking in a subpopulation of mice to explore changes in excitatory and inhibitory neurotransmission neurons of the medial prefrontal cortex and dorsal striatum, two brain regions that have generally been overlooked in studies of opiate plasticity. These experiments will provide significant contributions to opiate addiction literature as well as potential pharmacotherapeutic targets to mitigate relapse.