Co-administration of Anti microRNA-124 and -137 Oligonucleotides Prevents Hippocampal Neural Stem Cell Loss Upon Non-convulsive Seizures

Abstract

Convulsive seizures promote adult hippocampal neurogenesis (AHN) through a transient activation of neural stem/progenitor cells (NSPCs) in the subgranular zone (SGZ) of the dentate gyrus (DG). However, in a significant population of epilepsy patients, non-convulsive seizures (ncSZ) are observed. The response of NSPCs to non-convulsive seizure induction has not been characterized before. We here studied first the short-term effects of controlled seizure induction on NSPCs fate and identity. We induced seizures of controlled intensity by intrahippocampally injecting increasing doses of the chemoconvulsant kainic acid (KA) and analyzed their effect on subdural EEG recordings, hippocampal structure, NSPC proliferation and the number and location of immature neurons shortly after seizure onset. After establishing a KA dose that elicits ncSZ, we then analyzed the effects of ncSZ on NSPC proliferation and NSC identity in the hippocampus. ncSZ specifically triggered neuroblast proliferation, but did not induce proliferation of NSPCs in the SGZ, 3 days post seizure onset. However, ncSZ induced significant changes in NSPC composition in the hippocampus, including the generation of reactive NSCs. Interestingly, intrahippocampal injection of a combination of two anti microRNA oligonucleotides targeting microRNA-124 and -137 normalized neuroblast proliferation and prevented NSC loss in the DG upon ncSZ. Our results show for the first time that ncSZ induce significant changes in neuroblast proliferation and NSC composition. Simultaneous antagonism of both microRNA-124 and -137 rescued seizure-induced alterations in NSPC, supporting their coordinated action in the regulation of NSC fate and proliferation and their potential for future seizure therapies.

The piRNA pathway sustains adult neurogenesis by reducing protein synthesis and cellular senescence

“…Images were obtained using the microscope Nikon Eclipse at 20x or 40x magnification and quantification was performed using a Cell-counter plugin in Fiji. DAB staining was performed as previously reported (Bielefeld et al, 2019). Briefly, sections were incubated with peroxidase block (Vectashield), permeabilized with 0.3% PBS-Triton X (PBS-T) and 0.1% PBS-T.…”

“…Kainic Acid to elicit tonic, non-convulsive epileptic seizures, was administered as described before (Bielefeld et al, 2019). Briefly, 50nL of 2.22mM Kainic Acid dissolved in PBS (pH 7.4) was injected bilaterally into the hippocampus at the following coordinates (AP -2.0, ML +/-1.5, DV -2.0 mm) (between 9AM and 1PM).…”

Robust chronic convulsive seizures, high frequency oscillations, and human seizure onset patterns in an intrahippocampal kainic acid model in mice

“…Brief (3-7 sec) abnormalities were reported by others where they could be as frequent as 100 per hr (Kim et al, 2018; Sandau et al, 2019; Lai et al, 2020). Sometimes the EEG examples that were published suggested trains of spikes or epileptiform activity occurred in the wks after IHKA, but seizures were either rare, not shown, or the evidence that they occurred was not strong (e.g., Kiasalari et al, 2016; Zhu et al, 2016; Runtz et al, 2018; Bielefeld et al, 2019; Li et al, 2020). One study that described methods for IHKA in mice concluded that IHKA did not lead to epilepsy (Bielefeld et al, 2017).…”

Adult Neural Stem Cell Regulation by Small Non-coding RNAs: Physiological Significance and Pathological Implications

“…Key signaling pathways acting as regulators of NSC quiescence include, among others, Notch (Ehm et al, 2010 ; Imayoshi et al, 2010 ; Lugert et al, 2010 ), ephrins in endothelial cells (Ottone et al, 2014 ), cadherins in ependymal cells (Porlan et al, 2014 ), BMP, WNT (Li and Clevers, 2010 ; Mira et al, 2010 ), GABAergic (Song et al, 2012 ; Giachino et al, 2014 ), and glutamatergic signaling (Lugert et al, 2010 ; Sierra et al, 2015 ; Bielefeld et al, 2019 ). For an extensive overview of all signaling pathways and proteins involved in maintaining aNSC quiescence, we refer to an excellent recent review (Urbán et al, 2019 ).…”