Exp Neurobiol.  2017 Oct;26(5):287-294. 10.5607/en.2017.26.5.287.

Structural and Functional Alterations at Pre-Epileptic Stage Are Closely Associated with Epileptogenesis in Pilocarpine-induced Epilepsy Model

Affiliations
  • 1Department of Neurology, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, Korea. leeh@ewha.ac.kr
  • 2Department of Medical Science, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, Korea.
  • 3Department of Anatomy, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, Korea.
  • 4Neuroscience Research Institute, Gachon University, Incheon, Korea.

Abstract

Pilocarpine-induced rat epilepsy model is an established animal model that mimics medial temporal lobe epilepsy in humans. The purpose of this study was to investigate neuroimaging abnormalities in various stages of epileptogenesis and to correlate them with seizure severity in pilocarpine-induced rat epilepsy model. Fifty male Sprague-Dawley rats were subject to continuous video and electroencephalographic monitoring after inducing status epilepticus (SE) and seizure severity was estimated by frequency and total durations of class 3 to 5 spontaneous recurrent seizures (SRS) by modified Racine's classification. The 7.0 Tesla magnetic resonance imaging (MRI) with high resolution flurodeoxyglucose positron emission tomography (FDG-PET) was performed at 3 hours, 1, 3, 7 days and 4 weeks after the initial insult. The initial SRS was observed 9.7±1.3 days after the pilocarpine injection. MRI revealed an abnormal T2 signal change with swelling in both hippocampi and amygdala in acute (day 1 after injection) and latent phases (days 3 and 7), in association with PET hypometabolism in these areas. Interestingly, the mean frequency of class 3 to 5 SRS was positively correlated with abnormal T2 signals in hippocampal area at 3 days. SRS duration became longer with more decreased glucose metabolism in both hippocampi and amygdala at 7 days after pilocarpine injection. This study indicates that development and severity of SRS at chronic phase could be closely related with structural and functional changes in hippocampus during the latent period, a pre-epileptic stage.

Keyword

Temporal lobe epilepsy; Pilocarpine; Epileptogenesis; MRI; FDG-PET

MeSH Terms

Amygdala
Animals
Classification
Epilepsy*
Epilepsy, Temporal Lobe
Glucose
Hippocampus
Humans
Magnetic Resonance Imaging
Male
Metabolism
Models, Animal
Neuroimaging
Pilocarpine
Positron-Emission Tomography
Rats
Rats, Sprague-Dawley
Seizures
Status Epilepticus
Glucose
Pilocarpine
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