Hyperexcitability in Cortical Neurons and Transient Seizure Suppression with mTOR Inhibition in a Mouse Model of TSC
Abstract number :
2.251
Submission category :
7. Anti-seizure Medications / 7A. Animal Studies
Year :
2023
Submission ID :
784
Source :
www.aesnet.org
Presentation date :
12/3/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Luis Martinez, PhD – Baylor College of Medicine/Texas Children's Hospital
Anne Anderson, MD – Professor, Pediatrics, Baylor College of Medicine; Xiaolong Jing, PhD – Assistant Professor, Neuroscience, Baylor College of Medicine; Wai Lee, PhD – Research Associate, Pediatrics, Baylor College of Medicine; QianQian Ma, PhD – Research Associate, Neuroscience, Baylor College of Medicine
Rationale: Tuberous Sclerosis Complex (TSC) is a genetic disorder caused by mutations in TSC1 or TSC2 genes and is characterized by brain malformations and severe epilepsy in up to ninety percent of patients. mTOR inhibitors can reduce seizure burden in some TSC patients but may not have a disease-modifying effect. Using a TSC mouse model with spontaneous seizures, we evaluated the changes in cellular excitability and synaptic connectivity of cortical neurons in multiple layers due to TSC2 deficiency with whole-cell recordings. In whole animal studies, we evaluated the effects of conventional anti-seizure medication (ASM)[(phenobarbital (PHB)] compared to the mTOR inhibitor RAD001.
Methods: Mouse pups with conditional forebrain deletion of the Tsc2 gene in excitatory neurons were treated with vehicle (VEH), PHB (25mg/kg once daily), or RAD001 (6mg/kg every other day) by intraperitoneal route starting on postnatal day eight (P8). vEEG activity was recorded and analysis of epileptiform and seizure activity was performed. mTOR signaling was assessed using western blotting of cortical tissue at various time points. Cortical slices were prepared for whole-cell patch recordings of excitatory and inhibitory postsynaptic potentials acquired by Quadro EPC 10 amplifiers, PatchMaster software (HEKA), and custom-written Matlab-based programs.
Results: PHB had no effect on seizure activity or survival of Tsc2 KO mice, whereas the mTOR inhibitor RAD001 normalized pS6 levels, abolished seizure activity, and prolonged the lifespan of NEX-Tsc2 mice (p< 0.001). Treatment with RAD001 significantly delayed the development of seizures from P12 to approximately P50. pS6 levels were reduced and comparable to WT VEH (p >0.05) starting after the first dose of RAD001 to P35 but increased at P45 (p< 0.05). Whole-cell recordings from Tsc2 KO mice revealed enhanced excitatory and inhibitory synaptic events compared to WT (p< 0.05). This enhancement was restricted to layer six neurons, while other layers remained unchanged compared to WT.
Anti-seizure Medications