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Brain Stimul. 2019 Jun 7. pii: S1935-861X(19)30260-8. doi: 10.1016/j.brs.2019.06.009. [Epub ahead of print]

Electrical stimulation of the ventral hippocampal commissure delays experimental epilepsy and is associated with altered microRNA expression.

Author information

1
Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, University Hospital Frankfurt and Center for Personalized Translational Epilepsy Research (CePTER), Goethe University, Frankfurt, Germany; Department of Neurology, Philipps University, Marburg, Germany. Electronic address: laracostard@rcsi.com.
2
Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, University Hospital Frankfurt and Center for Personalized Translational Epilepsy Research (CePTER), Goethe University, Frankfurt, Germany; Department of Neurology, Philipps University, Marburg, Germany.
3
Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.
4
Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
5
Lab of Systems Neuroscience, Institute for Neuroscience, Department of Health Science and Technology, ETH Zurich, Zurich, Switzerland.
6
Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland; FutureNeuro Research Centre, Royal College of Surgeons in Ireland, Dublin, D02, Ireland.

Abstract

BACKGROUND:

Up to 80% of mesial temporal lobe epilepsy patients with hippocampal sclerosis (mTLE-HS) are resistant to pharmacological treatment, often necessitating surgical resection. Deep brain stimulation (DBS) has emerged as an alternative treatment for patients who do not qualify for resective brain surgery. Brain stimulation may also exert disease-modifying effects, and noncoding microRNAs have recently been proposed to shape the gene expression landscape in epilepsy.

OBJECTIVE:

We compared the effect of DBS of 4 different hippocampal target regions on epileptogenesis and manifest epilepsy in a rat model of mTLE-HS. To explore mechanisms, we profiled the effect of the most effective DBS paradigm on hippocampal microRNA levels.

METHODS:

MTLE-HS was induced by electrical stimulation of the perforant pathway (PP) in rats. This paradigm leads to spontaneous seizures within 4 weeks. We investigated DBS of 4 targets: PP, fimbria fornix (FF) formation, dentate gyrus (DG) and ventral hippocampal commissure (VHC). We applied both high- (130 Hz) and low-frequency (5 Hz or 1 Hz) stimulation. Functional microRNAs were identified in the hippocampus immediately after VHC-DBS and after a 97-day recording period by sequencing small RNAs bound to Argonaute-2, a component of the miRNA silencing complex.

RESULTS:

Low frequency DBS of the VHC significantly delayed the occurrence of the first spontaneous recurrent seizure in the PPS model by ∼300%, from 19 to 56 days. No other stimulation regime altered the latency phase. Upregulation of 5 microRNAs during epileptogenesis was suppressed by VHC-stimulation.

CONCLUSION:

We conclude that DBS of the VHC delays epilepsy in the PPS model in rats and is associated with differential regulation of several miRNAs. Additional studies are required to determine whether VHC-regulated miRNAs serve causal roles in the anti-epileptogenic effects of this DBS model.

KEYWORDS:

Deep brain stimulation; Hippocampal sclerosis; Mesial temporal lobe epilepsy; Ventral hippocampal commissure; microRNA

PMID:
31208877
DOI:
10.1016/j.brs.2019.06.009

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