Spontaneous and odor-evoked seizures in Synapsin I/II/III knockout mice: electrophysiological characterization Marco Cambiaghi 1 , Marco Cursi 1 , Luis Teneud 1 , Elena Monzani 2 , Fabio Minicucci 1 , Giancarlo Comi 1 , Flavia Valtorta 2 , Letizia Leocani 1 1 Neurological Department, INSPE and 2 Neuropsychopharmacology Unit; Neuroscience Division, San Raffaele, Scientific Institute and Vita-Salute University, Milan, Italy Introduction. Approximately 1% of the human population suffers from some form of epilepsy 1 and the studies of animal models are of great advantage for the study of underlying mechanisms and new therapeutic strategies. Synapsins (SynI, SynII, SynIII) are a multigene family of synaptic vesicle (SV) phosphoproteins implicated in the regulation of synaptic transmission and plasticity 2,3 . The genetic inactivation of either synapsin I and II leads to epilepsy, and the phenotype is more severe when both genes are inactivated 4 . On the contrary, synapsin I/II/III KO (triple knockout, TKO) mice exhibit a milder epileptic phenotype, displaying only rare spontaneous seizures 3 . Objectives. The aim of this project is to study the electrophysiological behavior of Syn-TKO mice epilepsy by video-EEG analysis. Methods. We implanted brain epidural screw electrodes in adult Syn-TKO and matched wt mice to record video-EEG and a wire electrode to concomitantly record EMG. We analyzed spontaneous and odor-evoked seizures 5 and the baseline interictal EEG in awake freely-moving animals by power spectrum measures. Results. EEG seizures did not differ in duration and morphology between spontaneous and odor-evoked. In half of the recorded seizures we found a typical post-critical phase at about 4 Hz frequency, characterized by complete immobility of the animals. The power spectrum analysis of interictal EEG revealed a difference in 2-3 Hz and 7-9 Hz potency and peak-frequency between the two groups. Conclusions. These preliminary data indicate that Syn-TKO are characterized by an altered baseline EEG activity and that seizures can be followed by an absence-like phenotype. This rare-epilepsy animal model could be of great interest in studying SV relevance in spontaneous and evoked neuronal network firing. Summary 1. Pugliatti, M. et al., 2007. Estimating the cost of epilepsy in Europe: a review with economic modeling. Epilepsia – Dec;48(12):2224-33 2. Rosahl, T. et al., 1995. Essential functions of synapsin I and II in synaptic vescicle regulation. Nature – Jun 8;375(6531):488-93 3. Cesca F. et al., 2010. The synapsins: key actors of synapse function and plasticity. Prog. Neurobiol. - Aug;91(4):313-48 4. Etholm, L. and Heggelund P., 2009. Seizure elements and seizure element transitions during tonic-clonic seizure activity in the synapsin I/II double knockout mouse: A neuroethological description. Epilepsy and Behavior – Apr;14(4):582-90 5. Tsubone H., et al., 1978. Odor evoking of epileptic seizures in IDT mice. Jap. J. Vet. Sci. – Apr;40(2):213-6 Bibliography Results Experimental Method Conclusions  To our knowledge, this is the first description of spontaneous and odor- evoked seizures in Syn I/II/III Ko mice in vivo. Seizures in Syn-DKO 4 and Syn-TKO are similar in length (31.1 vs 30.5 sec). Our finding of odor-induced seizures suggest the possibility that evoked seizures in Syn-DKO 4 and Syn-TKO 3 when handling the cage may also be related to olfactory stimulation  Postictal phases with 3-4 Hz EEG oscillations associated with animal immobility are firstly described in this animal model, and confirm the usefulness of videoEEG in monitoring epileptic mice, since electrical abnormalities may occur without evident behavioural abnormalities. Power spectrum analysis may reveal brain bioelectrical dysfunction independently from the occurrence of seizures Future studies comparing Syn-DKO and Syn-TKO electrophysiological features are needed The use of video-EEG and quantitative spectral analysis may be useful to monitor and investigate the physiopathology of animal models of epilepsy, even with rare spontaneous seizures EEG postictal activity SynI/II/III Ko mice Postictal activity in SynI/II/III mice is sometimes characterized by a 4Hz frequency (range 3-7) with a complete immobility of the animal (7/19 seizures). Average duration= 107 sec (range: 30-210 sec). Background EEG activity in SynI/II/III Ko mice Power spectrum of basal EEG of Wt and Syn I/II/III Ko mice. Peak freqency: Wt=8.12Hz - SynI/II/III=7Hz (p<0.05; n=12 and n=4) All these notes and proceedings are confidential. You are bound not to communicate or disclose these information and results to any third party. Active electrodes Reference electrode Seizure duration spontaneous (n=14) evoked (n=5) average 31.08 sec 29.80 sec st. err. 4.08 4.83 2 sec 500 μV * * * * 400 μV 3 sec 500 μV 2 sec Background activity Spontaneous seizure Postictal phase Animal implant Recording cage 0 1 2 3 4 5 6 7 8 9 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Wt Syn-TKO Frequencies EEG power (normalized) Example of SynI/II/III Ko mice spontaneous seizure Average duration of spontaneous and evoked seizures in Syn I/II/III Ko mice (hours of recording: Wt 95h – SynI/II/III 930h) * Adult Syn I/II/III Ko mice electrode implant Sites of epidural electrodes Three epidural screw electrodes were fixed with dental cement to the skull. Two active electrode were positioned over parietal areas, while the reference/ground over cerebellum. right left EMG right left EMG right left EMG Evoked seizures To record odor-evoked seizures, Syn I/II/III Ko mice were put in a small cage (22x25 cm) within a cotton ball soaked with a strong odor substance 5 . Customized Faraday’s Cage used for EEG recording F1000 Posters. Copyright pro ht protected. F1000 Posters. Copyright protected. F100 sters. Copyright protected. F1000 Posters. Copyright protected. F1000 Posters. Co ed. F1000 Posters. Copyright protected. F1000 Posters. Copyright protected. F1000 Posters. Cop pyright protected. F1000 Posters. Copyright protected. F1000 Posters. Copyright protected. F1000 Posters. Copyright protected. F1000 Posters. Copyright protected. F1000 Posters. Copyright pro opyright protected. F1000 Posters. Copyright protected. F1000 Posters. cted. F1000 Posters. Copyright protected. F1 Posters. Copyright