Flurothyl-induced seizure paradigm revealed higher seizure susceptibility in middle-aged Angelman syndrome mouse model

Abstract

IntroductionEpilepsy is one of the main clinical problems in Angelman syndrome (AS). Seizures typically start in early childhood then decrease or are often alleviated by young adulthood. Several studies using AS model mice showed comparable seizure susceptibility during young adulthood. In contrast, the course of epilepsy post young adulthood differs from persistently relieved to rerising among reports. To elucidate this, we evaluated the seizure susceptibility of AS model mice of two different ages. MethodsMice lacking maternal Ube3a gene (Ube3am–/p+) of C57BL/6 background or their littermate wild type (WT) were divided into two groups by age, 2 to 3 months (2–3 M) and 6 to 12 months (6–12 M), corresponding to adolescent to young adult aged and middle aged humans, respectively. Seizure susceptibility was evaluated by flurothyl inhalation or intraperitoneal injection of pentylenetetrazole (PTZ IP)-induced acute seizure protocol. ResultsIn the flurothyl-induced seizure paradigm, the latency to seizure occurrence had a significant interaction with genotype and age. Post-hoc analysis revealed that the latency was significantly shorter at 6–12 M than at 2–3 M in Ube3am-/p+ mice, and in Ube3am-/p+ mice than in WT mice at 6–12 M. No significant interaction or difference was observed by PTZ IP. ConclusionThe flurothyl-induced seizure paradigm revealed that seizure susceptibility of Ube3am-/p+ mice increased with age, similar to clinical studies reporting the reappearance of epilepsy in older age. The flurothyl-induced seizure paradigm applied to middle-aged Ube3am–/p+ mice could be a suitable protocol for screening drugs against seizures in AS.