Presentations

Abstract

Introduction: Piezo1 is a non-selective, mechanosensitive cation channel first described in 2010. It contains multiple transmembrane alpha helices and three-bladed propeller-like structure. Piezo1 is activated by mechanical forces on cell membranes, leading to calcium influx and many downstream effects. While Piezo1 has been implicated in neurodegenerative diseases such as Alzheimer's disease, it remains poorly studied in epilepsy, despite studies showing increased hippocampal sclerosis related to epileptic zone in patients with mesial temporal lobe epilepsy (MTLE) and increased hippocampal Piezo1 expression in mice 24 hours following MTLE, correlating with increased expression of pro-inflammatory cytokines. While several molecular mechanisms are involved in epileptogenesis, the goal of this study was to quantify early expression of Piezo1 immediately following Status Epilepticus (SE) relevant to epileptogenesis.

Methods: The Pilocarpine-induced SE model (250 mg/kg i.p. Pilocarpine) and its control (0.9% i.p. saline) were conducted in adult male C57BL/6J Mice (N=15, Jackson Laboratories). Clinical seizures were monitored using Rancine scores. After euthanasia, brain samples were prepared for histology studies. For immunohistochemistry, Piezo1 was detected using a rabbit anti-Piezo1 antibody (extracellular portion), a biotinylated goat anti-rabbit secondary antibody, and DAB. Sections were counterstained with Cresyl Violet. Images of the whole hippocampus were obtained blinded at 4x with an Olympus BX53F2 microscope. Piezo1 immunoreactivity levels were quantified in the whole hippocampus. Statistical analyses were conducted with JMP using a Wilcoxon two-sample test. In addition, publicly available Piezo1 RNAseq data from the Human Protein Atlas was analyzed to evaluate baseline differences in Piezo1 RNA expression by sex and age (40-49, 50-59, 60-69, 70-79 years) in control human brain samples (N=187).

Results: Preliminary data indicate that expression of Piezo 1 was localized to the hippocampus, particularly the dentate gyrus and stratum moleculare of CA1. Immunoreactivity analysis indicate that there is no statistically significant difference in the percent area of Piezo1 staining in the whole hippocampus. In human controls, there were no statistically significant differences in Piezo1 RNA levels in brain between sex and age groups.

Conclusion: Although Piezo1 may not be involved in the early stages of epileptogenesis, it can be activated late in the development of epilepsy. This data indicate a potential time window for translation intervention. Further analyses are needed, including colocalizing Piezo1 with synaptic markers, quantifying cortical expression, and a Piezo1 ELISA. While future experiments should include female mice, preliminary data in human brains showed no baseline difference in Piezo1 RNA expression. Future experiments could also use additional timepoints following SE and chronic epilepsy.