Electrobehavioral Phenotype and Pharmacosensitivity of GAT-1 Deficient Mice
Abstract number :
3.169
Submission category :
3. Neurophysiology / 3F. Animal Studies
Year :
2021
Submission ID :
1826625
Source :
www.aesnet.org
Presentation date :
12/6/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:55 AM
Authors :
Britta Lindquist, MD, PhD - University of California at San Francisco & Gladstone Institute of Neurological Disease; Jeanne Paz, PhD - Associate Professor, Gladstone Institute
Rationale: SLC6A1 encodes GAT1, a high-affinity GABA transporter expressed on glia and presynaptic terminals of inhibitory neurons. Mutations in SLC6A1 are associated with myotonic-atonic epilepsy, absence epilepsy, autism and intellectual disability. A patient-derived SLC6A1 mutation has recently been identified, encoding GAT1S295L. We hypothesized that GAT1S295L expression would facilitate the development of seizures in a mouse model.
Methods: We implanted n=40 male and female mice from 5 genotypes (GAT1-/- knock-out (KO), GAT1-/+ heterozygote (Het), GAT1S295L/+ knock-in (KI), and respective GAT1+/+ wildtype (WT) littermates) with EMG and ECoG (AP +1, ML +2.5mm from Bregma) electrodes for chronic awake freely behaving electrophysiology in the home cage, assessed at baseline and in response to pharmacologic manipulations.
Results: GAT1-deficient and -mutant mice had frequent absence seizures, characterized by 7Hz spike-wave discharges with behavioral arrest. Relative to WT mice, heterozygous and KO mice had gene dose-related increases in epileptic spikes, detected as events >7-fold RMS amplitude (WT 1.7±0.4 vs Het 5.8±2.7 vs KO 9.37±2.96 spikes/min, n=9,8,9, ANOVA p< 0.0001) and seizure burden, assessed from area under the curve of spike instantaneous frequency (WT 53.4±12.7 vs Het 193.9±32.8 vs KO 281.0±39.7 arbitrary units (AU), n=9,8,9, p< 0.0001 ANOVA). GAT1S295L/+ KI mice had more epileptic spikes (KI 4.3±0.7 vs WT 1.7±0.5 spikes/min, n=7,6, p< 0.05 t-test) and a larger seizure burden than WT littermates (KI 170.1±37.5 vs WT 55.8±16.8 AU, n=7,6, p< 0.05 t-test). Across genotypes, seizure burden during a 48-hour nesting task correlated inversely with nest quality (Pearson R2=0.34, p< 0.001). WT and heterozygous mice developed abundant spike-wave discharges after receiving GAT1 antagonist NO-711 (10mg/kg i.p.) compared with vehicle (saline 0.1ml/10g body weight), whereas the drug had no effect on KO mice (WT 2.2±0.5 veh vs 46.0±10.3 spikes/min NO, n=7, p< 0.01 RM-ANOVA, p< 0.01 Dunnett’s multiple comparison test; Het 7.9±2.5 veh vs 48.2±6.4 spikes/min NO, n=7, p=0.0001 RM-ANOVA, p=0.001 Dunnett’s; KO 14.0±4.0 veh vs 20.5±10.5 spikes/min NO, n=7, p=0.26). Similarly, NO-711 increased spike frequency in KI as well as WT littermates (Het 5.2±1.1 veh vs 67.2±13.0 spikes/min NO, n=8, p< 0.01 RM-ANOVA, p< 0.01 Dunnett’s; WT 1.5±0.8 veh vs 54.4±7.5 spikes/min NO, n=5, p< 0.01 RM-ANOVA, p< 0.01 Dunnett’s). T-type Ca
Neurophysiology