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

描述(申请人提供)：在我们的临床前研究中，我们发现Tac2通路可能是一个有吸引力的候选通路，可以防止创伤事件后PTSD的发展。啮齿动物的Tac2基因(人类的Tac3)编码神经激肽B(NKB)神经肽，它与神经激肽3受体(NK3)结合，NK3是一种G蛋白偶联受体。NkB和Nk3是速激肽家族，广泛分布于大脑中，作为神经递质和神经调节剂，具有多种生物学功能，包括调节情绪和学习。此前，其他速激肽通路，如神经激肽1受体(NK1)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，证明Tac2、Nkb和Nk3在中央杏仁核(CEA，形成恐惧记忆的关键亚结构)都高表达，参与了情绪学习过程。具体地说，利用RNA微阵列、定量聚合酶链式反应和原位杂交等方法，我们发现Tac2基因在CEA中受到线索恐惧条件作用后的动态调控。此外，单次全身和CEA内注射Nk3拮抗剂会损害线索-恐惧记忆的巩固。因此，这一探索性/发展性R21建议旨在通过过度表达和沉默Tac2基因来更好地了解Tac2通路，以进一步了解其在恐惧条件反射中的作用。此外，我们的目标是研究Tac2表达的细胞在恐惧学习中通过光遗传兴奋和抑制Tac2表达的细胞在CEA中的特定作用。总之，这些研究将对Tac2/Nk3通路在恐惧学习的巩固过程中的作用提供新的理解。这些发现将激励和支持一项新的研究计划，旨在翻译Tac2/Nk3通路的调制，为恐惧和创伤暴露后的干预提供新的方法，以预防创伤后应激障碍。

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.