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Updated: Mar 22, 2026
Inducing Post-Traumatic Epilepsy in a Mouse Model of Repetitive Diffuse Traumatic Brain Injury
Published on: February 10, 2020
Serial Quantitative TSPO-Targeted PET Reveals Peak Microglial Activation up to 2 Weeks After an Epileptogenic Brain
Mirjam Brackhan1, Pablo Bascuñana2, Johannes M Postema2
1Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany; and Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine, Hannover, Germany.
Unlabelled:
Experimental and clinical evidence suggests that neuroinflammation, triggered by epileptogenic insults, contributes to seizure development. We used translocator protein-targeted molecular imaging to obtain further insights into the role of microglial activation during epileptogenesis.
Methods:
As epileptogenic insult, a status epilepticus (SE) was induced in rats by lithium pilocarpine. Rats were subjected to (11)C-PK11195 PET scans before SE; at 4 h after SE; at 1, 2, 5, 7, 14, and 22 d after SE; and at 14-16 wk after SE. For data evaluation, brain regions were outlined by coregistration with a standard rat brain atlas, and percentage injected dose/cm(3) and binding potential (simplified reference tissue model with cerebellar gray matter as a reference region) were calculated. For autoradiography and immunohistochemical evaluation, additional rats were decapitated without prior SE or 2, 5, or 14 d after SE.
Results:
After SE, increases in (11)C-PK11195 uptake and binding potential were evident in epileptogenesis-associated brain regions, such as the hippocampus, thalamus, or piriform cortex, but not in the cerebellum beginning at 2-5 d and persisting at least 3 wk after SE. Maximal regional signal was observed at 1-2 wk after SE. Autoradiography confirmed the spatiotemporal profile. Immunohistochemical evaluation revealed microglial and astroglial activation as well as neuronal cell loss in epileptogenesis-associated brain regions at all investigated time points. The time course of microglial activation was consistent with that demonstrated by tracer techniques.
Conclusion:
Translocator protein-targeted PET is a reliable tool for identifying brain inflammation during epileptogenesis. Neuroinflammation mainly affects brain regions commonly associated with seizure generation and spread. Definition of the time profile of neuroinflammation may facilitate the development of inflammation-targeted, antiepileptogenic therapy.
Insights
Neuroinflammation, detected using translocator protein-targeted PET scans, is linked to seizure development. This imaging technique can identify brain inflammation during epileptogenesis, aiding in the development of targeted therapies.
Area of Science:
- Neuroscience
- Molecular Imaging
- Neuroinflammation
Background:
- Neuroinflammation is implicated in seizure development following brain injury.
- Microglial activation is a key component of the neuroinflammatory response.
- Understanding the temporal dynamics of neuroinflammation is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the role of microglial activation in epileptogenesis using translocator protein-targeted molecular imaging.
- To characterize the spatiotemporal profile of neuroinflammation following an epileptogenic insult.
Main Methods:
- Status epilepticus (SE) was induced in rats using lithium pilocarpine.
- (11)C-PK11195 Positron Emission Tomography (PET) scans were performed at various time points post-SE.
- Autoradiography and immunohistochemistry were used for validation.
Main Results:
- Increased (11)C-PK11195 uptake and binding potential were observed in brain regions associated with epileptogenesis (hippocampus, thalamus, piriform cortex) starting 2-5 days after SE and persisting for at least 3 weeks.
- Maximal tracer signal occurred 1-2 weeks post-SE.
- Immunohistochemistry confirmed microglial and astroglial activation, alongside neuronal loss, in affected brain regions.
Conclusions:
- Translocator protein-targeted PET is a reliable method for detecting brain inflammation during epileptogenesis.
- Neuroinflammation is concentrated in brain regions critical for seizure generation and propagation.
- Mapping the time course of neuroinflammation can inform the development of anti-epileptogenic therapies targeting inflammation.
