Facilitation of Extinction Retention and Reconsolidation Blockade by IV Allopregnanolone in PTSD

以创伤为中心的心理治疗在创伤后应激障碍(PTSD)中显示出普遍的疗效。然而， 这种治疗对症状的改善在创伤后应激障碍患者中可能有很大的不同。 几个因素可能影响治疗反应，包括影响大脑的神经生物学因素 在恢复期间重新处理创伤记忆和巩固重新配置的大脑回路所需的能力。 在以创伤为中心的治疗中，与威胁相关的记忆的激活使记忆“不稳定”和 涉及两个相互竞争的过程：灭绝和重新整合。灭绝包括：a)激活 前额叶皮质(PFC)抑制杏仁核介导的生理和行为防御反应，以及 获取和巩固新的学习(例如，条件化威胁刺激或CS不再发出信号 在新的时空背景下的威胁)。在分子水平上，灭绝既涉及突触的长期 增强(LTP)和长期抑制(LTD)。因此，灭绝改善了功能，但不是永久性的，如 杏仁核介导的防御反应可能会在新的背景下重新出现，当重新暴露在原始环境中时 威胁，或者随着时间的流逝。创伤后应激障碍与消亡学习障碍和 留存。再巩固障碍也可能有助于创伤后应激障碍的恢复。蛋白质合成抑制剂(NOT 在人类中可行)，β-受体阻滞剂，蛋白激酶A(PKA)抑制剂可以阻止再巩固(如果在 一小时短暂的威胁记忆重新激活)，后者通过破坏丝氨酸845残基的磷酸化 Glu-R1AMPA受体，从而限制了它们的突触结合--这是记忆重新巩固的先决条件。 此后，前CS-US联系被“记住”，但杏仁核介导的防御反应被“记住”。 不是由CS共同激活的。在拟议的研究中，我们的目标是使用标准的3天差异恐惧- 证明促进灭绝保持的条件性范式(摘录。1)和重新整合封锁 (摘自2)适时静脉注射别孕酮(Allo)。Allo是一种代谢物 正向调节GABAA受体上GABA效应的孕酮；Allo的硫酸代谢物 拮抗NMDA受体。患有创伤后应激障碍的男性和女性患上等位素缺乏症和低休息的风险很高。 等位基因一直与物种灭绝保持能力差有关。相比之下，在简要之后管理Allo类似物 在缺乏同种异体基因的啮齿动物中，重新激活条件性恐惧已被证明阻碍了再巩固。摘录。1 在第二项研究中，128名患有创伤后应激障碍的男性和女性将接受不同的恐惧条件作用(第一天)。在这一天 实验2/21，IV Allo与安慰剂相比，将在灭绝训练后输注，以将血浆Allo提高到静息水平 与最佳消光保持相关；消光保持将在第三天进行测试。在Expt的第二天。2， 大剂量静脉注射Allo与安慰剂相比，将在单个CS重新激活恐惧记忆后立即给予， 重新整合封锁将在第三天进行测试。如果这项研究成功，Allo可能会 在难治性创伤后应激障碍患者的治疗中加强创伤聚焦治疗。

Trauma-focused psychotherapies show general efficacy in posttraumatic stress disorder (PTSD). However, symptom improvement in response to such treatments can vary substantially among individuals with PTSD. Several factors may contribute to treatment response including neurobiological factors that impact brain capacities needed to reprocess trauma memories and consolidate reconfigured brain circuits during recovery. During trauma-focused therapies, activation of a threat-related memory renders the memory “labile” and engages two competing processes: extinction and reconsolidation. Extinction involves: a) activation of prefrontal cortical (PFC) inhibition of amygdala-mediated physiological and behavioral defense responses, and acquisition and consolidation of new learning (e.g., the conditioned threat stimulus or CS+ no longer signals threat in the new time-space context). At the molecular level, extinction involves both synaptic long-term potentiation (LTP) and long-term depression (LTD). Extinction thus improves function, but is not permanent, as amygdala-mediated defense responses may reemerge in a new context, upon re-exposure to the original threat, or with the passage of time. PTSD has been associated with deficits in both extinction learning and retention. Reconsolidation blockade also may contribute to PTSD recovery. Protein synthesis inhibitors (not feasible in humans), beta-blockers, protein kinase A (PKA) inhibitors can block reconsolidation (if given within an hour of brief threat memory reactivation), the latter by disrupting phosphorylation of serine 845 residues on Glu-R1 AMPA receptors, thus limiting their synaptic incorporation—a prerequisite for memory reconsolidation. Thereafter, the former CS+-US association is “remembered”, but amygdala-mediated defense responses are not co-activated by the CS+. In the proposed study, we aim to use a standard 3-day differential fear- conditioning paradigm to demonstrate facilitation of extinction retention (Expt. 1) and reconsolidation blockade (Expt. 2) by appropriately timed intravenous (IV) administration of allopregnanolone (Allo). Allo is a metabolite of progesterone that positively modulates GABA effects at GABAA receptors; sulfated metabolites of Allo antagonize NMDA receptors. Men and women with PTSD are at high risk for Allo deficiency, and low resting Allo has been associated with poor extinction retention. In contrast, administration of an Allo analog after brief reactivation of conditioned fear in Allo-deficient rodents has been shown to block reconsolidation. In Expts. 1 and 2 of the study, 128 men and women with PTSD will undergo differential fear conditioning (Day 1). On Day 2 of Expt. 1, IV Allo vs. placebo will be infused after extinction training to raise plasma Allo to resting levels associated with optimum extinction retention; extinction retention will be tested on Day 3. On Day 2 of Expt. 2, high dose IV Allo vs. placebo will be administered immediately after fear memory reactivation by a singe CS+, and reconsolidation blockade will be tested on Day 3. If this study is successful, Allo could potentially be administered to augment trauma-focused therapy in treatment refractory PTSD patients.