The early and lasting mechanisms underlying predator odor stressor-induced adaptations to alcohol interoceptive sensitivity

项目总结/摘要 创伤后应激障碍（PTSD）可以由创伤性应激源促成，并且是一种持久的， 只有有限的治疗选择存在的衰弱性疾病。此外，PTSD会增加个体的 发展为共病酒精使用障碍（AUD）的可能性，表明了解的重要性 压力和酒精敏感性之间关系的大脑机制。酒精内感受性 敏感性是指酒精对生物体的主观刺激作用。因此，内感受灵敏度 具有告知酒精摄入的潜力（即，信号饱或驱动更多的饮酒）。由于临床 局限性，很少有人知道的大脑机制，压力诱导的敏感性降低， 酒精因此，我们建议使用一种公认的捕食者气味暴露（2，5-二氢-2，4，5- 三甲基噻唑啉（TMT））应激模型，大鼠已表现出持久的行为后果 与PTSD有关。应激与皮质谷氨酸功能失调有关。同意下 在临床应激文献中，我发现大鼠皮质中mGlu受体基因表达的改变， TMT曝光。具体地说，Grm 3（mGlu 3）在前边缘皮层（PrL）中下调，两天后， TMT曝光。此外，几种NMDA受体基因转录物（GriN 2A、GriN 2B、GriN 2C、GriN 2D、 GriN 3A和GriN 3B）在TMT暴露后2周在岛叶皮质（IC）中上调。这是 重要的是，NMDA受体调节酒精的内感受性作用的表达，我的初步研究表明， 数据表明，在相同的剂量下，先前暴露于TMT的大鼠对酒精的内感受性敏感性降低， 时间点（TMT后2周）。因为IC参与了酒精内感受性加工， PrL的主要输出，我假设由PrL（mGlu 3）突触IC回路之间的应激诱导的可塑性 触发了与NMDA相关的大脑IC的变化，这可能是对内感受器敏感性减弱的基础。 酒精的影响。目的1探讨TMT应激过程中发生的潜在机制，以促进 酒精内感受敏感性的变化。实验1.1使用mGlu 3负变构调节剂（NAM）， 在TMT暴露前立即阻断PrL中的mGlu 3受体信号传导，并确定这是否 治疗可防止2周后对酒精的敏感性减弱。Exp. 1.2使用化学遗传学方法 在TMT暴露之前，抑制从PrL到IC的突触能投射，以评估这种治疗是否 会阻止酒精内感受性的减弱目的2研究NMDA受体是否 IC中的适应是对酒精敏感性减弱的基础。Exp. 2.1确定TMT暴露 在来自IC神经元的光诱发EPSC中产生NMDA受体适应，所述IC神经元接收来自 PrL。Exp. 2.2研究了对IC NMDA受体的功能适应， 对酒精敏感。总之，这些实验将阐明早期和持久的大脑机制， 是压力诱导的酒精内感受敏感性适应的基础。

PROJECT SUMMARY/ABSTRACT Post-traumatic stress disorder (PTSD) can be precipitated by a traumatic stressor and is an enduring and debilitating disorder for which only limited treatment options exist. Furthermore, PTSD increases an individual’s likelihood to develop a co-morbid alcohol use disorder (AUD), demonstrating the importance of understanding the brain mechanisms underlying the relationship between stress and alcohol sensitivity. Alcohol interoceptive sensitivity refers to the subjective stimulus effects of alcohol on an organism. As such, interoceptive sensitivity has the potential to inform alcohol intake (i.e., signal satiety or drive more drinking). However, due to clinical limitations, little is known about brain mechanisms that underlie stressor-induced diminished sensitivity to alcohol. Therefore, we propose to use a well-established predator odor exposure (2,5‐dihydro‐2,4,5‐ trimethylthiazoline (TMT)) stressor model in rats that has demonstrated lasting behavioral consequences relevant to PTSD. Stress is associated with dysregulated cortical glutamate function. In agreement with the clinical stress literature, I find altered expression of mGlu receptor gene expression in the rat cortex following TMT exposure. Specifically, Grm3 (mGlu3) was downregulated in the prelimbic cortex (PrL) two days after TMT exposure. Additionally, several NMDA receptor gene transcripts (GriN2A, GriN2B, GriN2C, GriN2D, GriN3A, and GriN3B) were upregulated in the insular cortex (IC) 2 weeks after the TMT exposure. This is important as NMDA receptors modulate expression of the interoceptive effects of alcohol, and my preliminary data demonstrate diminished interoceptive sensitivity to alcohol in rats previously exposed to TMT at the same time point (2 weeks after TMT). Because the IC is involved in alcohol interoceptive processing and is one of the major outputs of the PrL, I hypothesize that plasticity induced by stress between PrL (mGlu3)IC circuitry triggers the NMDA-related brain changes in the IC that may underlie the blunted sensitivity to the interoceptive effects of alcohol. Aim 1 investigates the potential mechanisms that occur during the TMT stressor to promote the changes to alcohol interoceptive sensitivity. Exp 1.1 uses an mGlu3 negative allosteric modulator (NAM) to block mGlu3 receptor signaling in the PrL immediately prior to TMT exposure, and to determine if this treatment prevents the attenuated sensitivity to alcohol 2 weeks later. Exp. 1.2 uses a chemogenetic approach to silence glutamatergic projections from the PrL to the IC prior to TMT exposure, to assess if this treatment will prevent the blunted alcohol interoceptive sensitivity. Aim 2 investigates whether the NMDA receptor adaptations in the IC underlie the attenuated sensitivity to alcohol. Exp. 2.1 determines if TMT exposure produces NMDA receptor adaptation in optically evoked EPSC’s from IC neurons receiving projections from the PrL. Exp. 2.2 investigates the functional adaptations to IC NMDA receptors that underlie the attenuated sensitivity to alcohol. Together, these experiments will elucidate the early and lasting brain mechanisms that underlie stressor-induced adaptations to alcohol interoceptive sensitivity.