Vagus nerve stimulation modulates synaptic plasticity in the rat prefrontal cortex during the extinction of drug-seeking

吸毒导致形成强烈的暗示/奖励联系，这种联系在戒毒和戒毒后持续很长时间。 增加了复发的长期风险。打破这些联系是治疗物质的一个重要目标 使用障碍。消亡是一种学习形式，它抑制了对习得刺激的行为反应。调制 消亡过程和巩固新形成的记忆具有重塑适应不良行为的临床潜力 并防止复发。我们最近的研究表明，迷走神经刺激(VNS)可促进消退学习和 减少线索诱导的可卡因自我给药大鼠寻求药物的恢复。这些变化与 以下缘(IL)皮质为中心的网络活动发生变化。我们的初步数据还显示，吸毒 和恢复减少了第5层IL锥体神经元的AMPA受体电流，而VNS逆转了这些变化。 灭绝期间全身阻断TrkB受体对脑源性神经营养因子(BDNF)的作用可消除VNS 对线索诱导的恢复和IL中谷氨酸能传递的影响。我们假设灭绝训练 逆转药物诱导的IL中突触AMPAR的变化。将灭绝与VNS配对导致(额外的)BDNF释放 这巩固了这些变化并减少了恢复。在此应用程序中，我们将结合使用行为、 电生理和细胞类型特定的形态分析，以1)进一步调查时间和电路特定的 白介素性神经适应障碍导致药物寻找和复发，以及2)确定其机制 VNS通过它来巩固消退记忆，以减少复发。目标1中的实验将使用膜片钳 杏仁基底外侧核(BLA)传入IL的电生理和光发生刺激测定 这些输入是如何被寻求毒品、灭绝和VNS改变的。我们将执行两种类型的电压钳制录音 IL投射神经元(到BLA和伏隔核外壳)的变化，并确定VNS引起的突触后变化 谷氨酸受体功能与消退和恢复时的突触前释放。这些实验将是 同类型IL投射神经元的形态分析支持确定VNS诱导的变化 特别是在通过恢复(由活性标记pCREB标记)激活的细胞中，以测试我们的假设 VNS优先调制与VNS配对的行为相关的网络。在目标2中，我们将确定是否 VNS诱导的灭绝巩固依赖于IL或其输入中的内源性BDNF水平。为此，我们将 使用CRISPR/Cas9敲除白质内细胞或海马区细胞产生的BDNF 分别投射到IL，以确定VNS诱发的BDNF如何调节消亡和恢复。 Aim 3中的实验将确定VNS诱导的BDNF释放对突触可塑性和 调控复发的细胞的形态。我们还将记录BLA和NAC外壳中的活体局部场势，以 确定BDNF基因敲除如何影响VNS在IL输出中调节突触可塑性的能力。已被占用 总之，我们的研究将为可卡因和消退诱导的脑内突触变化提供重要的新信息。 IL，他们将确定谷氨酸和BDNF依赖的机制，通过这些机制，VNS可以减少复发。

Drug use causes the formation of strong cue/reward associations which persist long after cessation of drug-taking and contribute to the long-term risk of relapse. Breaking these associations is an important goal in the treatment of substance use disorders. Extinction is a form of learning that inhibits behavioral responses to a learned stimulus. Modulating extinction processes and consolidating the newly-formed memories has clinical potential to reshape maladaptive behavior and to prevent relapse. We have recently shown that vagus nerve stimulation (VNS) facilitates extinction learning and reduces cue-induced reinstatement of drug-seeking in cocaine self-administering rats. These changes correlate with altered activity in a network that centers on the infralimbic (IL) cortex. Our preliminary data also show that drug-taking and reinstatement reduce AMPA-receptor currents at layer 5 IL pyramidal neurons, and that VNS reverses these changes. Systemic blockade of TrkB receptors for the brain-derived neurotrophic factor (BDNF) during extinction abolishes VNS’ effects on cue-induced reinstatement and on glutamatergic transmission in the IL. We hypothesize that extinction training reverses drug-induced changes in synaptic AMPARs in the IL. Pairing extinction with VNS leads to (additional) BDNF release which consolidates these changes and reduces reinstatement. In this application we will use a combination of behavioral, electrophysiological, and celltype-specific morphological analyses to 1) further investigate the time- and circuit-specific dysfunctional neuroadaptations in the IL that contribute to drug-seeking and relapse, and 2) to determine the mechanisms through which VNS consolidates extinction memory to reduce relapse. Experiments in Aim 1 will use patch-clamp electrophysiology and optogenetic stimulation of afferents from the basolateral amygdala (BLA) to the IL to determine how these inputs are altered by drug-seeking, extinction, and VNS. We will perform voltage-clamp recordings from 2 types of IL projection neurons (to the BLA and Nucleus accumbens shell) and determine VNS-induced changes in postsynaptic glutamate receptor function and presynaptic release during extinction and reinstatement. These experiments will be supported with morphological analyses in the same type of IL projection neurons to determine VNS-induced changes specifically in cells that were activated by reinstatement (labeled by the activity marker pCREB) to test our hypothesis that VNS preferentially modulates networks relevant in behaviors paired with VNS. In Aim 2 we will determine whether the VNS-induced consolidation of extinction depends on endogenous BDNF levels in the IL or its inputs. To this end we will use CRISPR/Cas9 to knock down BDNF produced either from cells within the IL or from cells in the hippocampus that project to the IL, respectively, in order to determine how VNS-evoked BDNF modulates extinction and reinstatement. Experiments in Aim 3 will determine the importance of VNS-induced BDNF release to changes in synaptic plasticity and morphology in cells that regulate relapse. We will also record in-vivo local field potentials in the BLA and the NACshell to determine how BDNF knockdown affects VNS’ ability to modulate synaptic plasticity in the outputs of the IL. Taken together, our studies will provide important novel information about cocaine- and extinction-induced synaptic changes in the IL, and they will identify glutamatergic and BDNF-dependent mechanisms through which VNS can reduce relapse.