Functional dissection of the Tac2-Nk3R pathway to prevent fear consolidation

描述（由申请人提供）：在我们的临床前研究中，我们发现Tac 2通路可能是预防暴露于创伤事件后PTSD发展的有吸引力的候选者。啮齿类动物中的Tac 2基因（人类中的Tac 3基因）编码神经激肽B（Nk B）神经肽，该神经肽与神经激肽3受体（Nk 3）（一种G蛋白偶联受体）结合。NkB和Nk 3是速激肽，其是广泛分布于脑中的神经肽家族，其充当具有多种生物功能（包括调节情绪和学习）的神经递质和神经调质。以前，其他速激肽途径，如神经激肽1受体（NK 1）和P物质，已被描述为参与恐惧过程。然而，我们提供了第一个证据表明，Tac 2，NkB和Nk 3，都高度表达在中央杏仁核（CeA，恐惧记忆形成的关键子结构）参与情绪学习过程。具体而言，使用RNA微阵列，qPCR和原位杂交方法，我们发现，Tac 2基因的动态调节后，线索恐惧条件反射在CeA。此外，一个单一的全身和内CeA剂量的NK 3拮抗剂损害线索恐惧巩固记忆。因此，这个探索/发展R21的建议是为了获得更好地了解Tac 2途径的过表达和沉默的Tac 2基因，以进一步了解其在恐惧条件反射的作用。此外，我们的目标是研究在CeA内的Tac 2表达细胞通过光遗传学的兴奋和抑制Tac 2表达细胞在恐惧学习过程中的具体作用。这些研究将为Tac 2/Nk 3通路在恐惧学习巩固过程中的作用提供新的认识。这些发现将激发和支持一项新的研究计划，旨在翻译Tac 2/Nk 3通路的调节，为预防PTSD提供恐惧和创伤暴露后的干预新方法。

DESCRIPTION (provided by applicant): In our preclinical studies, we have found that the Tac2 pathway might be an attractive candidate to prevent the development of PTSD after exposure to a traumatic event. The Tac2 gene in rodents (Tac3 in humans) encodes the neurokinin B (NkB) neuropeptide which binds to the neurokinin 3 receptor (Nk3), a G-protein-coupled receptor. NkB and Nk3 are tachykinins, a family of neuropeptides widely distributed in the brain that act as neurotransmitters and neuromodulators having a variety of biological functions including modulation of emotion and learning. Previously, other tachykinin pathways, such as neurokinin 1 receptor (NK1) and substance P, have been described to be involved in fear processes. However, we provide the first evidence that Tac2, NkB and Nk3, all highly expressed in the central amygdala (CeA, a key substructure for the formation of fear memories) are involved in emotional learning processes. Specifically, using RNA microarray, qPCR and in situ hybridization approaches, we found that the Tac2 gene is dynamically regulated after cued-fear conditioning in the CeA. Moreover, a single systemic and intra-CeA dose of a Nk3 antagonist impaired cued-fear consolidation of memory. Thus, this Exploratory/Developmental R21 proposal is intended to gain a better understanding of the Tac2 pathway by overexpressing and silencing the Tac2 gene to further our understanding of its role in fear conditioning. Moreover, we aim to study the specific role of the Tac2 expressing cells within the CeA via optogenetic excitation and inhibition of Tac2-expressing cells during fear learning. Together these studies will provide a new understanding of the role of the Tac2/Nk3 pathway in the consolidation process underlying fear learning. These findings will energize and support a new research program aimed at translating the modulation of the Tac2/Nk3 pathway to provide novel approaches to intervention following fear and trauma exposure for the prevention of the PTSD.