Functional Role of Neurogenesis in Hippocampal Mossy Fiber Sprouting

项目摘要 癫痫是一种慢性疾病，可以在各种神经损伤后发展，包括创伤性脑损伤 受伤中风和感染然而，尽管多年的研究，癫痫的发展机制， 从最初的神经损伤中恢复过来仍然是难以捉摸的。在海马齿状回，癫痫发作驱动 颗粒细胞苔藓纤维轴突的病理性逆行发芽。虽然发芽可能有助于 癫痫发生，苔藓纤维发芽的生理后果是未知的。此外，齿状 脑回是成体神经发生的场所，成体颗粒细胞可能直接产生出芽苔藓 纤维，虽然这是广泛争论和未解决的。在我们手中，初步数据显示成年人- 初生的颗粒细胞确实会产生出芽的苔藓纤维，在内部分子层中形成大的终扣 齿状回此外，成熟颗粒细胞的全细胞膜片钳记录表明， 这些成人出生的神经元在功能上有助于复发性兴奋回路。该项目的目标是 更好地理解海马过度兴奋的机制，并提供有针对性的 未来的治疗机制，以防止癫痫。我们的总体假设是， 细胞提供了大量的苔藓纤维发芽，这些异常的突触产生了反复出现的微电路 在海马体中驱动失控的兴奋。这一假设将使用毛果芸香碱进行检验。 癫痫模型和转基因标记的年龄确定的队列的颗粒细胞在小鼠中。苔藓纤维发芽 将通过颗粒细胞的免疫荧光染色进行定量，并将使用全细胞电生理学 利用颗粒细胞的光遗传学刺激检测复发回路并询问发芽的突触 同伙这项提案的具体目标是独立检查成人出生的颗粒细胞的贡献 苔藓纤维发芽和发芽突触的生理特性。此外，该提案 研究发芽苔藓纤维的沉默是否可以减弱海马的过度兴奋， 与癫痫有关。总的来说，这个建议的目的是了解电路重排功能 影响癫痫海马体，以便未来的治疗可以针对癫痫疾病，而不是 症状

Project Summary Epilepsy is a chronic condition that can develop after various neurological insults, including traumatic brain injury, stroke, and infection. However, despite years of study, the mechanism for the development of epilepsy from an initial neurological insult has remained elusive. In the hippocampal dentate gyrus, seizures drive pathologic retrograde sprouting of granule cell mossy fiber axons. Although sprouting may contribute to epileptogenesis, the physiologic consequences of mossy fiber sprouting are unknown. Additionally, the dentate gyrus is a locus for adult neurogenesis and adult-born granule cells might directly give rise to sprouted mossy fibers, though this is widely debated and unresolved. In our hands, preliminary data has indicated that adult- born granule cells do give rise to sprouted mossy fibers, which form large boutons in the inner molecular layer of the dentate gyrus. Moreover, whole-cell patch clamp recordings from mature granule cells indicate that these adult-born neurons functionally contribute to recurrent excitatory circuitry. The goal of this project is to better understand mechanisms that contribute to hippocampal hyperexcitability and provide a targetable mechanism for future treatments to prevent epileptogenesis. Our overall hypothesis is that adult-born granule cells provide the bulk of mossy fiber sprouting and that these aberrant synapses create recurrent microcircuits that drive runaway excitation within the hippocampus. This hypothesis will be tested using the pilocarpine model of epilepsy and transgenic labeling of age-defined cohorts of granule cells in mice. Mossy fiber sprouting will be quantified by immunofluorescent staining of granule cells, and whole-cell electrophysiology will be used to detect recurrent circuits and interrogate the sprouted synapse using optogenetic stimulation of granule cell cohorts. The specific aims of this proposal independently examine the contribution of adult-born granule cells to mossy fiber sprouting and the physiological properties of a sprouted synapse. Furthermore, this proposal investigates whether silencing of sprouted mossy fibers can attenuate the hippocampal hyperexcitability that is associated with epilepsy. Taken together, this proposal aims to understand circuit rearrangements functionally affect the epileptic hippocampus, so that future treatments can target the disease of epilepsy, rather than the symptoms.