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Updated: Jun 14, 2026
Assessment of Memory Function in Pilocarpine-induced Epileptic Mice
Published on: June 4, 2020
Microglial ablation and lipopolysaccharide preconditioning affects pilocarpine-induced seizures in mice
Martine M Mirrione1, Dorothy K Konomos, Iordanis Gravanis
1Department of Pharmacological Sciences, Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, NY 11794-8651, USA.
Abstract:
Activated microglia have been associated with neurodegeneration in patients and in animal models of Temporal Lobe Epilepsy (TLE), however their precise functions as neurotoxic or neuroprotective is a topic of significant investigation. To explore this, we examined the effects of pilocarpine-induced seizures in transgenic mice where microglia/macrophages were conditionally ablated. We found that unilateral ablation of microglia from the dorsal hippocampus did not alter acute seizure sensitivity. However, when this procedure was coupled with lipopolysaccharide (LPS) preconditioning (1 mg/kg given 24 h prior to acute seizure), we observed a significant pro-convulsant phenomenon. This effect was associated with lower metabolic activation in the ipsilateral hippocampus during acute seizures, and could be attributed to activity in the mossy fiber pathway. These findings reveal that preconditioning with LPS 24 h prior to seizure induction may have a protective effect which is abolished by unilateral hippocampal microglia/macrophage ablation.
Insights
Microglia ablation in the hippocampus abolished the protective effect of lipopolysaccharide preconditioning against seizures. This suggests microglia play a crucial role in seizure modulation.
Area of Science:
- Neuroscience
- Immunology
- Epilepsy Research
Background:
- Activated microglia are implicated in neurodegeneration, but their role in Temporal Lobe Epilepsy (TLE) remains debated.
- Understanding microglia's neurotoxic or neuroprotective functions is crucial for TLE research.
Purpose of the Study:
- To investigate the role of microglia/macrophages in seizure sensitivity and the effects of lipopolysaccharide (LPS) preconditioning in a mouse model of TLE.
- To determine if ablating microglia impacts acute seizure sensitivity and LPS-induced pro-convulsant effects.
Main Methods:
- Used pilocarpine to induce seizures in transgenic mice with conditionally ablated microglia/macrophages in the dorsal hippocampus.
- Administered lipopolysaccharide (LPS) 24 hours prior to seizure induction in conjunction with microglia ablation.
- Assessed seizure sensitivity and hippocampal metabolic activation.
Main Results:
- Unilateral ablation of hippocampal microglia did not affect acute seizure sensitivity.
- Microglia ablation abolished a significant pro-convulsant phenomenon observed with LPS preconditioning.
- This effect was linked to reduced metabolic activation in the ipsilateral hippocampus and involved the mossy fiber pathway.
Conclusions:
- Lipopolysaccharide (LPS) preconditioning exhibits a protective effect against seizures, which is dependent on the presence of microglia/macrophages.
- Microglia/macrophage ablation in the hippocampus negates the protective effects of LPS preconditioning, highlighting their critical role in modulating seizure activity.
