Absence-like Seizures, Cortical Oscillations Abnormalities and Decreased Anxiety-like Behavior in Wistar Audiogenic Rats with Cortical Microgyria

• Published in: Neuroscience 2022-09, Vol.500, p.26-40
• Main Authors: Klippel Zanona, Querusche, Alves Marconi, Gabriel, de Sá Couto Pereira, Natividade, Lazzarotto, Gabriela, Ferreira Donatti, Ana Luiza, Cortes de Oliveira, José Antonio, Garcia-Cairasco, Norberto, Calcagnotto, Maria Elisa
• Format: Article
• Language: English
• Subjects: EEG; electrophysiology; freeze-lesion; spike-wave discharges; Wistar audiogenic rats
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2022.07.032

•Naive Wistar Audiogenic Rats (WARs) have SWD)-like absence seizures.•Naive WARs have abnormal cortical oscillation.•Microgyria in naive WARs worsens SWD events and abnormal cortical oscillations.•Naive WARs with cortical microgyria have reduced anxiety-like behavior.•This two his model has advantages to study epileptogenesis during development. Wistar Audiogenic Rats (WAR) is an inbred rodent strain susceptible to acute auditory stimulation-induced seizures. However, spontaneous epileptic seizures (SES) and their associated electroencephalogram (EEG) abnormalities have not been reported in WAR kindled animals. The same is true for naïve WARs (without sound-induced seizures). An approach to increment epileptogenesis and SES is to use a second insult to be added to the genetic background. Here, we used adult naïve WARs with microgyria induced by neonatal cortical freeze-lesion (FL) to evaluate the occurrence of SES and the modification in cortical oscillation patterns and behavior. The neonatal cortical FL was performed in Wistar and naïve WARs (Wis-FL and WAR-FL). Sham animals were used as controls (Wistar-S and WAR-S). Video-EEG recordings and behavioral tasks were performed during adulthood. Surprisingly, spike-waive discharges (SWD) events associated with behavior arrest were detected in WAR-S rats. Those events increased in duration and number in WAR-FL animals. The EEG quantitative analysis showed decreased power of cortical delta, theta and beta oscillations in WAR-S, decreased power of cortical fast gamma (FG) oscillations in WARs, independent of microgyria, and decreased interhemispheric synchrony for delta and FG with stronger coupling in delta and theta-FG oscillations in FL animals. The WARs, regardless of microgyria, had reduced locomotor activity, but only WAR-FL animals had reduced anxiety-like behavior. Microgyria in naïve WARs intensified SWD events associated with behavior arrest that could reflect absence-like seizures and abnormal cortical oscillations, and reduced anxiety-like behavior indicating that WAR-FL could be a reliable model to study epileptogenesis.