table_2_Denervated mouse CA1 pyramidal neurons express homeostatic synaptic plasticity following entorhinal cortex lesion.xlsx

Structural, functional, and molecular reorganization of denervated neural networks is often observed in neurological conditions. The loss of input is accompanied by homeostatic synaptic adaptations, which can affect the reorganization process. A major challenge of denervation-induced homeostatic plasticity operating in complex neural networks is the specialization of neuronal inputs. It remains unclear whether neurons respond similarly to the loss of distinct inputs. Here, we used in vitro entorhinal cortex lesion (ECL) and Schaffer collateral lesion (SCL) in mouse organotypic entorhino-hippocampal tissue cultures to study denervation-induced plasticity of CA1 pyramidal neurons. We observed microglia accumulation, presynaptic bouton degeneration, and a reduction in dendritic spine numbers in the denervated layers 3 days after SCL and ECL. Transcriptome analysis of the CA1 region revealed complex changes in differential gene expression following SCL and ECL compared to non-lesioned controls with a specific enrichment of differentially expressed synapse-related genes observed after ECL. Consistent with this finding, denervation-induced homeostatic plasticity of excitatory synapses was observed 3 days after ECL but not after SCL. Chemogenetic silencing of the EC but not CA3 confirmed the pathway-specific induction of homeostatic synaptic plasticity in CA1. Additionally, increased RNA oxidation was observed after SCL and ECL. These results reveal important commonalities and differences between distinct pathway lesions and demonstrate a pathway-specific induction of denervation-induced homeostatic synaptic plasticity.

在神经系统疾病中，去神经支配神经网络的结构、功能及分子重构现象屡见不鲜。输入信号的丧失伴随稳态突触适应性变化，这一过程会影响神经网络重构。在复杂神经网络中，去神经支配诱导的稳态可塑性研究面临的一大挑战是神经元输入的特异性。目前仍不清楚神经元对不同类型输入信号丧失的响应是否具有一致性。本研究利用小鼠器官型内嗅皮层-海马组织培养模型的体外内嗅皮层损伤（entorhinal cortex lesion, ECL）与施弗尔侧支损伤（Schaffer collateral lesion, SCL），探究CA1锥体神经元去神经支配诱导的可塑性变化。研究发现，在施弗尔侧支损伤与内嗅皮层损伤后的第3天，损伤靶区可见小胶质细胞聚集、突触前末梢变性以及树突棘数量减少。对CA1区域的转录组分析显示，相较于未损伤对照组，施弗尔侧支损伤与内嗅皮层损伤后均出现复杂的差异基因表达变化，且内嗅皮层损伤后差异表达基因更富集于突触相关功能通路。这一结果与实验现象相符：内嗅皮层损伤后第3天可观察到兴奋性突触的稳态可塑性变化，而施弗尔侧支损伤组未出现该现象。通过化学遗传学抑制内嗅皮层（而非CA3），进一步证实了CA1区域稳态突触可塑性的通路特异性诱导。此外，施弗尔侧支损伤与内嗅皮层损伤后均出现RNA氧化水平升高。本研究揭示了不同神经通路损伤之间的重要共性与差异，并证明去神经支配诱导的稳态突触可塑性具有通路特异性。