Biology subjects

Rosenow, F.

Publications and source records attributed to Rosenow, F..

5 recordsLinked to original sources

bioRxiv2025

Hippocampal network activity changes during early epileptogenesis predict subsequent epilepsy

The circuit mechanisms underlying focal epileptogenesis are, despite of decades of epilepsy research, still incompletely understood. In this study, we aimed to characterize the changes in hippocampal network activity induced by a potentially epileptogenic insult. In rats, long-lasting electrical perforant pathway stimulation leads in a high percentage of animals to the development of temporal lobe epilepsy. However, a subset of animals remains resilient against the stimulation. We monitored alterations of neuronal activity by chronically recording the local field potential (LFP) from the hippocampal dentate gyrus before, during and after the potentially epileptogenic insult. Intriguingly, epilepsy animals identified by subsequent spontaneous epileptic seizures were characterized by a transient increase in the aperiodic exponent suggesting a shift towards a reduced local excitation-to-inhibition (E/I) ratio during the first days after the perforant path stimulation. Furthermore, these animals developed a strong impairment of theta oscillation prevalence and regularity during early epileptogenesis. In contrast, resilient non-epilepsy animals without spontaneous seizures neither showed this modulation in E/I ratio nor a corruption of hippocampal theta activity. In fact, the increase in the aperiodic exponent on the first day after completion of the electrical stimulation paradigm could predict epileptogenesis with very high fidelity (AUC 0.92) and correlated significantly with later seizure rate. This finding opens the opportunity to dissect mechanisms of epileptogenesis and to test the effectiveness of anti-epileptogenesis treatment in very early disease stages by allowing identification of individuals at high risk. Furthermore, it might offer a potential explanation for the frequently observed failure of anti-epileptogenesis drugs boosting GABAergic inhibition.

neuroscience↗

bioRxiv2024

Temporal Lobe Epilepsy is dominated by Region Specific Interictal Cortical Inhibition

Epilepsy is typically characterized by excessive neuronal excitability, manifesting as seizures and interictal epileptiform discharges (IEDs) in the EEG. However, the dynamics of excitation and inhibition (E/I balance) remain poorly understood. Here, we leverage the aperiodic exponent of the EEG power spectrum--a marker indicative of synaptic inhibition--to investigate shifts in E/I balance during antiseizure medication (ASM) tapering in patients with mesial temporal lobe epilepsy (TLE). We analyzed EEG data from 28 TLE patients and 25 controls with non-epileptic episodes (NEE) undergoing presurgical video EEG monitoring. Unexpectedly, TLE patients showed a localized increase in the aperiodic exponent in the ipsilesional temporal lobe during ASM tapering, absent in controls. This inhibition increase correlated with seizure latency and predicted seizure occurrence. Intracranial recordings from 10 TLE patients revealed higher aperiodic exponents in the lateral temporal cortex compared to the hippocampus, suggesting stronger inhibition in the lateral cortex. Notably, hippocampal IEDs triggered transient inhibitory responses in the lateral cortex, accompanied by increased high-frequency activity and disrupted hippocampus-to-lateral connectivity. These findings suggest that TLE likely involves complex inhibitory mechanisms beyond the epileptic focus in the interictal period, with neocortical inhibition potentially containing epileptic activity, and offers a new tool to map epileptic brain regions.

neuroscience↗

bioRxiv2022

MicroRNA-335-5p suppresses voltage-gated sodium channel expression and may be a target for seizure control

There remains an urgent need for new therapies for drug-resistant epilepsy (DRE). Sodium channel blockers are effective for seizure control in common forms of epilepsy, but loss of sodium channel function underlies some genetic forms of epilepsy. Approaches that provide bi-directional control of sodium channel expression are needed. MicroRNAs (miRNA) are small non-coding RNAs which negatively regulate gene expression. Here, we show that genome-wide miRNA screening of hippocampal tissue from a rat epilepsy model, mice treated with the novel anti-seizure medicine cannabidiol (CBD) and plasma from patients with DRE, converge on a single target, miR-335-5p. Pathway analysis on predicted and validated miR-335-5p targets identified multiple voltage-gated sodium channels (VGSCs). Intracerebroventricular injection of antisense oligonucleotides against miR-335-5p resulted in upregulation of Scn1a, Scn2a and Scn3a in the mouse brain and an increased action potential rising phase and greater excitability of hippocampal pyramidal neurons in brain slice recordings, consistent with VGSCs as functional targets of miR-335-5p. Blocking of miR-335-5p also increased voltage-gated sodium currents in human iPSC-derived neurons. Inhibition of miR-335-5p increased susceptibility to tonic-clonic seizures in the pentylenetetrazole seizure model, whereas AAV9-mediated overexpression of miR-335-5p reduced seizure severity and improved survival. These studies suggest modulation of miR-335-5p may be a means to regulate VGSCs and affect brain excitability and seizures. Changes to miR-335-5p may reflect compensatory mechanisms to control excitability and could provide new biomarker or therapeutic strategies for different types of drug-resistant epilepsy. Significance StatementDespite the clinical availability of over 30 anti-seizure medications (ASMs), around 30% of people with epilepsy do not achieve seizure freedom. MicroRNAs are small non-coding RNAs which negatively regulate protein expression by binding to target mRNAs. Here, we identified the brain-enriched miR-335-5p to be commonly altered in three heterogenous miRNA profiling datasets. Bi-directional modulation of miR-335-5p identified a potential homeostatic role of miR-335-5p in brain excitability involving voltage-gated sodium channels. Electrophysiological and in vivo approaches revealed pro-epileptic activity of miR-335-5p inhibition whereas overexpression of miR-335-5p resulted in anti-epileptic activity. Overall, targeting miR-335-5p could provide a new approach in the modulation of brain excitability, with possible therapeutic applications in drug-resistant epilepsies and other neurological diseases.

neuroscience↗

bioRxiv2019

A systems approach delivers a functional microRNA catalog and expanded targets for seizure suppression in temporal lobe epilepsy

MicroRNAs (miRNAs) are short noncoding RNAs that shape the gene expression landscape, including during the pathogenesis of temporal lobe epilepsy (TLE). In order to provide a full catalog of the miRNA changes that happen during experimental TLE, we sequenced Argonaute 2-loaded miRNAs in the hippocampus of three different animal models at regular intervals between the time of the initial precipitating insult to the establishment of spontaneous recurrent seizures. The commonly upregulated miRNAs were selected for a functional in vivo screen using oligonucleotide inhibitors. This revealed anti-seizure phenotypes upon inhibition of miR-10a-5p, miR-21a-5p and miR-142a-5p as well as neuroprotection-only effects for inhibition of miR-27a-3p and miR-431-5p. Proteomic data and pathway analysis on predicted and validated targets of these miRNAs indicated a role for TGF{beta} signaling in a shared seizure-modifying mechanism. Together, these results identify functional miRNAs in the hippocampus and a pipeline of new targets for seizure control in epilepsy.

neuroscience↗

bioRxiv2017

Heterogeneous Contribution of Microdeletions in the Development of Common Generalized and Focal epilepsies

BackgroundMicrodeletions are known to confer risk to epilepsy, particularly at genomic rearrangement \"hotspot\" loci. However, deciphering their role outside hotspots and risk assessment by epilepsy sub-type has not been conducted.\n\nMethodsWe assessed the burden, frequency and genomic content of rare, large microdeletions found in a previously published cohort of 1,366 patients with Genetic Generalized Epilepsy (GGE) plus two sets of additional unpublished genome-wide microdeletions found in 281 Rolandic Epilepsy (RE) and 807 Adult Focal Epilepsy (AFE) patients, totaling 2,454 cases. These microdeletion sets were assessed in a combined analysis and in sub-type specific approaches against 6,746 ethnically matched controls.\n\nResultsWhen hotspots are considered, we detected an enrichment of microdeletions in the combined epilepsy analysis (adjusted-P= 2.00x10-7; OR = 1.89; 95%-CI: 1.51-2.35), where the implicated microdeletions overlapped with rarely deleted genes and those involved in neurodevelopmental processes. Sub-type specific analyses showed that hotspot deletions in the GGE subgroup contribute most of the signal (adjusted-P = 1.22x10-12; OR = 7.45; 95%-CI = 4.20-11.97). Outside hotspot loci, microdeletions were enriched in the GGE cohort for neurodevelopmental genes (adjusted-P = 4.78x10-3; OR = 2.30; 95%-CI = 1.42-3.70), whereas no additional signal was observed for RE and AFE. Still, gene content analysis was able to identify known (NRXN1, RBFOX1 and PCDH7) and novel (LOC102723362) candidate genes affected in more than one epilepsy sub-type but not in controls.\n\nConclusionsOur results show a heterogeneous effect of recurrent and non-recurrent microdeletions as part of the genetic architecture of GGE and a minor to negligible contribution in the etiology of RE and AFE.

genetics↗