Abstracts

Dynamic Gene Regulation in Epileptogenesis in Animal Models of Epilepsy

Abstract number : 1.364
Submission category : 1. Translational Research: 1A. Mechanisms / 1A1. Epileptogenesis of acquired epilepsies
Year : 2016
Submission ID : 230468
Source : www.aesnet.org
Presentation date : 12/3/2016 12:00:00 AM
Published date : Nov 21, 2016, 18:00 PM

Authors :
Bao-Luen Chang, UCL Institute of Neurology, London, United Kingdom; Matthew Walker, UCL Institute of Neurology, London, United Kingdom; Dimitri Michael Kullmann, UCL Institute of Neurology, London, United Kingdom; and Stephanie Schorge, UCL Institute of N

Rationale: The mechanism of epileptogenesis remains obscure but several postulated pathways and mechanisms have been proposed, including dysfunctional or defective ion channels and receptors, neurotransmission signaling pathways, immunological and inflammatory pathways, as well as alternations in gene expression. Gene regulation in epileptogenesis, which might be impacted by disrupted transcription factors, plays an important role in defining the mechanisms of epilepsy. To investigate dynamic gene regulation in the epileptogenic process, the tetanus toxin model of focal neocortical epilepsy was used. We aim to identify important regulators of epileptogenesis for clarifying epileptogenic mechanisms and pathways driving epileptogenesis, in order to broaden the range of targets for epilepsy treatment. Methods: Adult male Sprague-Dawley rats (280-350g) received stereotaxic intracerebral microinjection of either tetanus toxin (experimental group) or 0.9% normal saline (control group) in visual cortex and wireless EEG transmitters were implanted for long term video EEG recordings. Three different time frames: acute (48-72 hours after first SZ), subacute (2 weeks after first SZ) and chronic (30 days after first SZ) stages, were used in both experimental and control group animals. RNA was extracted from the epileptogenic zone at the different time points then two-step quantitative real-time PCR was performed to assess the mRNA expression of 13 candidate genes. Statistical comparisons were made using ANOVA with Bonferroni’s test for multiple comparisons. Results: The mRNA expression of the different candidate genes reveals diverse regulatory behaviors in different time points during the process of epileptogenesis. In the acute stage, Neurogranin(NRGN), Glial fibrillary acidic protein(GFAP), Potassium voltage-gated channel subfamily A1(KCNA1), Repressor element 1 silencing transcription factor(REST), mammalian target of rapamycin( mTOR), and Chemokine C-C- motif ligand 2(CCL2) all showed a trend of up-regulation, while Brain-derived neurotrophic factor(BDNF), Inducible cAMP early repressor II(CREM/ICERII), ?-aminobutyric acid A receptor, alpha 5(GABRA5), Adenosine kinase(ADK), Synaptosomal-associated protein 25(SNAP25), Hyperpolization-activated cyclic nucleotide gated channels 1(HCN1), and HCN2 all had a tendency towards down-regulation compared to the control group. In the subacute stage, GFAP, SNAP25, REST and mTOR are all significantly up-regulated. Finally, while CCL2 is significantly up-regulated in the chronic stage and GABRA5 is significantly down-regulated in this stage. Conclusions: Our study discloses that GFAP, SNAP25, REST, and mTOR are all dynamically regulated during epileptogenesis. In addition, CCL2 up-regulation also strongly correlates with the establishment of epilepsy. The dynamic changes of GABRA5 expression suggest that the GABAergic system may be differently regulated in the early and late stages of epileptogenesis. Our work highlights how different candidate genes are not only differentially regulated during epileptogenesis, but how individual genes can change as epileptogenesis progresses. Funding: Medical Research Council, UK
Translational Research