Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice

Background: Mesial temporal lobe epilepsy (MTLE) is a prevalent form of focal epilepsy characterized by seizures originating from the hippocampus and adjacent regions. Neurostimulation presents an alternative for surgery-ineligible patients with intractable seizures. However, conventional approaches...

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Main Authors: Piret Kleis, Enya Paschen, Andrea Djie-Maletz, Andreas Vlachos, Carola A. Haas, Ute Häussler
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Neurobiology of Disease
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Online Access:http://www.sciencedirect.com/science/article/pii/S0969996125001810
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author Piret Kleis
Enya Paschen
Andrea Djie-Maletz
Andreas Vlachos
Carola A. Haas
Ute Häussler
author_facet Piret Kleis
Enya Paschen
Andrea Djie-Maletz
Andreas Vlachos
Carola A. Haas
Ute Häussler
author_sort Piret Kleis
collection DOAJ
description Background: Mesial temporal lobe epilepsy (MTLE) is a prevalent form of focal epilepsy characterized by seizures originating from the hippocampus and adjacent regions. Neurostimulation presents an alternative for surgery-ineligible patients with intractable seizures. However, conventional approaches have limited efficacy and require refinement for better seizure control. While hippocampal low-frequency stimulation (LFS) has shown promising seizure reduction in animal studies and small clinical cohorts, its mechanisms, sex-specific outcomes, and long-term effects remain unknown. Objectives: We aimed to identify the antiepileptic and cognitive outcomes and potential underlying mechanisms of long-term hippocampal LFS in chronically epileptic male and female mice. Methods: We used the intrahippocampal kainate mouse model replicating the features of MTLE: spontaneous seizures, hippocampal sclerosis, and memory deficits. During the chronic phase of epilepsy, we applied 1 Hz electrical LFS in the sclerotic hippocampus 6 h/day, four times/week for 5 weeks and examined its effects on epileptiform activity, spatial memory, and kainate-induced pathological features at cellular and synaptic levels. Results: Long-term hippocampal LFS consistently diminished focal seizures in epileptic male and female mice, with seizure reduction extending beyond the stimulation period. Additionally, long-term LFS relieved spatial memory deficits and reversed pathological modifications at perforant path-dentate granule cell synapses shortly after stimulation. LFS had no significant effect on secondarily generalized seizures, anxiety-like behaviour, neurogenesis, hippocampal sclerosis, or presynaptic vesicles in perforant path fibres. Conclusion: These findings provide clinically relevant insights into the seizure type-specific effects of hippocampal LFS, which, alongside synaptic and behavioural improvements, could contribute to enhanced seizure control and quality of life in MTLE patients.
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spelling doaj-art-2b6199d01e0b4a3f8d74b1ec15a69eb62025-08-20T01:52:55ZengElsevierNeurobiology of Disease1095-953X2025-08-0121210696510.1016/j.nbd.2025.106965Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic micePiret Kleis0Enya Paschen1Andrea Djie-Maletz2Andreas Vlachos3Carola A. Haas4Ute Häussler5Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany; Corresponding authors at: Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Breisacher Str. 64, 79106 Freiburg, Germany.Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, GermanyExperimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, GermanyDepartment of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, GermanyExperimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, GermanyExperimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany; BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany; Corresponding authors at: Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Breisacher Str. 64, 79106 Freiburg, Germany.Background: Mesial temporal lobe epilepsy (MTLE) is a prevalent form of focal epilepsy characterized by seizures originating from the hippocampus and adjacent regions. Neurostimulation presents an alternative for surgery-ineligible patients with intractable seizures. However, conventional approaches have limited efficacy and require refinement for better seizure control. While hippocampal low-frequency stimulation (LFS) has shown promising seizure reduction in animal studies and small clinical cohorts, its mechanisms, sex-specific outcomes, and long-term effects remain unknown. Objectives: We aimed to identify the antiepileptic and cognitive outcomes and potential underlying mechanisms of long-term hippocampal LFS in chronically epileptic male and female mice. Methods: We used the intrahippocampal kainate mouse model replicating the features of MTLE: spontaneous seizures, hippocampal sclerosis, and memory deficits. During the chronic phase of epilepsy, we applied 1 Hz electrical LFS in the sclerotic hippocampus 6 h/day, four times/week for 5 weeks and examined its effects on epileptiform activity, spatial memory, and kainate-induced pathological features at cellular and synaptic levels. Results: Long-term hippocampal LFS consistently diminished focal seizures in epileptic male and female mice, with seizure reduction extending beyond the stimulation period. Additionally, long-term LFS relieved spatial memory deficits and reversed pathological modifications at perforant path-dentate granule cell synapses shortly after stimulation. LFS had no significant effect on secondarily generalized seizures, anxiety-like behaviour, neurogenesis, hippocampal sclerosis, or presynaptic vesicles in perforant path fibres. Conclusion: These findings provide clinically relevant insights into the seizure type-specific effects of hippocampal LFS, which, alongside synaptic and behavioural improvements, could contribute to enhanced seizure control and quality of life in MTLE patients.http://www.sciencedirect.com/science/article/pii/S0969996125001810NeurostimulationDentate gyrusHippocampal sclerosisKainateStructural plasticitySpatial navigation
spellingShingle Piret Kleis
Enya Paschen
Andrea Djie-Maletz
Andreas Vlachos
Carola A. Haas
Ute Häussler
Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice
Neurobiology of Disease
Neurostimulation
Dentate gyrus
Hippocampal sclerosis
Kainate
Structural plasticity
Spatial navigation
title Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice
title_full Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice
title_fullStr Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice
title_full_unstemmed Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice
title_short Long-term hippocampal low-frequency stimulation alleviates focal seizures, memory deficits and synaptic pathology in epileptic mice
title_sort long term hippocampal low frequency stimulation alleviates focal seizures memory deficits and synaptic pathology in epileptic mice
topic Neurostimulation
Dentate gyrus
Hippocampal sclerosis
Kainate
Structural plasticity
Spatial navigation
url http://www.sciencedirect.com/science/article/pii/S0969996125001810
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