Exp Neurobiol 2017; 26(5): 287-294
Published online October 31, 2017
© The Korean Society for Brain and Neural Sciences
Hani Kim1†, Yunsook Choi1,2†, Hye-Young Joung1,2†, Yun Seo Choi1,2, Hyeon Jin Kim1,2, Yohan Joo4, Jin-Hwan Oh4, Hoo Jae Hann3, Zang-Hee Cho4 and Hyang Woon Lee1,2*
Departments of 1Neurology, 2Medical Science, and 3Anatomy, Ewha Womans University School of Medicine and Ewha Medical Research Institute, Seoul, Korea, 4Neuroscience Research Institute, Gachon University, Incheon, Korea
Correspondence to: *To whom correspondence should be addressed.
TEL: 82-2-2650-2673, FAX: 82-2-2650-5959
†These are co-first authors.
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.
Keywords: Temporal lobe epilepsy, Pilocarpine, Epileptogenesis, MRI, FDG-PET