Src deficient mice demonstrate behavioral and electrophysiological alterations relevant to psychiatric and developmental disease

Abstract

Much evidence suggests that hypofunction of the N-methyl-d-aspartate glutamate receptor (NMDAR) may contribute broadly towards a subset of molecular, cognitive and behavioral abnormalities common among psychiatric and developmental diseases. However, little is known about the specific molecular changes that lead to NMDAR dysfunction. As such, personalized approaches to remediating NMDAR dysfunction based on a specific etiology remains a challenge. Sarcoma tyrosine kinase (Src) serves as a hub for multiple signaling mechanisms affecting GluN2 phosphorylation and can be disrupted by convergent alterations of various signaling pathways. We recently showed reduced Src signaling in post mortem tissue from schizophrenia patients, despite increased MK-801 binding and NMDA receptor complex expression in the postsynaptic density (PSD). These data suggest that Src dysregulation may be an important underlying mechanism responsible for reduced glutamate signaling. Despite this evidence for a central role of Src in NMDAR signaling, little is known about how reductions in Src activity might regulate phenotypic changes in cognition and behavior. As such, the current study sought to characterize behavioral and electrophysiological phenotypes in mice heterozygous for the Src Acl gene (Src+/− mice). Src+/− mice demonstrated decreased sociability and working memory relative to Src+/+ (WT) mice while no significant differences were seen on locomotive activity and anxiety-related behavior. In relation to WT mice, Src+/− mice showed decreased mid-latency P20 auditory event related potential (aERP) amplitudes, decreased mismatch negativity (MMN) and decreased evoked gamma power, which was only present in males. These data indicate that Src+/− mice are a promising new model to help understand the pathophysiology of these electrophysiological, behavioral and cognitive changes. As such, we propose that Src+/− mice can be used in the future to evaluate potential therapeutic approaches by targeting increased Src activity as a common final pathway for multiple etiologies of SCZ and other diseases characterized by reduced glutamate function.