Altered striatal long-term potentiation in the eIF4E- TG ASD mouse model

Autism spectrum disorder (ASD) is associated with deficits in synaptic plasticity across brain regions. While striatal dysfunction is observed in various mouse models of ASD, the effect of ASD-associated genes on striatal plasticity has not been well characterised. We previously showed that overexpression of the SFARI ASD risk gene eIF4E in transgenic (eIF4E-TG) mice produces ASD-like behaviours and impairs dorsal striatal dopamine release. Here, we examined whether eIF4E overexpression alters striatal synaptic transmission and plasticity. Using microscopy, whole-cell electrophysiology, optogenetics and fast-scan cyclic voltammetry, we assessed dendritic morphology and excitatory synaptic properties of spiny projection neurons (SPNs). The eIF4E-TG mice exhibited higher dendritic spine density, elevated AMPA and NMDA receptor-mediated mEPSC frequency, and reduced AMPA mEPSC amplitude. We also observed an increased induction rate and magnitude of long-term potentiation (LTP) in SPNs, which is NMDA receptor-dependent but is not prevented by pharmacological D1 or D2 receptor antagonism under the conditions tested. Finally, we found that somatic and dendritic Ca2+ signals evoked by brief depolarisation are altered in SPNs from eIF4E-TG mice. Together, these findings are consistent with eIF4E overexpression promoting an NMDA receptor-dependent form of striatal LTP that is not prevented by D1/D2 receptor antagonism.