Mild Hyper-Excitation Induces Functional and Morphological Changes in Dendritic Spines in Mouse Brain Slices

Abstract

The dynamic properties of dendritic spines are crucial for the modulation of synaptic strength and plasticity. While most experimental efforts have explored dendritic spines in response to specific events such as synaptic plasticity or in various neurological disorders, the potential role of structural spine neck changes in regulating neuronal function remains obscure. It appears likely that dendritic spines can independently regulate signal transduction, particularly the magnitude of postsynaptic potential, via its neck. Here, we induced modest hyperexcitation in mouse hippocampal slices using the GABAA receptor blocker picrotoxin (PTX) to identify the earliest functional adjustments in the hippocampal circuit. After 30 minutes of PTX treatment, we investigated the intrinsic membrane and dendritic spine structure in CA1 pyramidal neurons. Modest hyperexcitation, without sustained discharging, did not induce changes in intrinsic neuronal properties. However, we did observe subtle changes in dendritic spine shape that may impact signaling independently of synaptic release and post-synaptic receptor mechanisms. Our ongoing efforts will explore whether these changes reflect a beneficial homeostatic response to maintain the balance or contribute to a slow shift in the excitation/inhibition balance