L'equilibio tra eccitazione ed inibizione nel sistema nervoso centrale: trasmissione sinaptica, plasticità e sinaptopatie

Objective of our research unit is to investigate the mechanisms governing excitatory/inhibitory homeostasis and to define whether and how their alteration contributes to the progressive cognitive decline and behavioural changes associated with different synaptopathies. To do that, we will focus on a small set of synaptic proteins that form macromolecular complexes and are involved in neuronal dysfunctions associated with different synaptopathies. The Unit will also collaborate with the other groups of the network to characterize excitatory and inhibitory synapse development in the mice models available in the network.

In particular the Unit will pursue the following objectives:



1) Establishment of Pure Glutamatergic and GABAergic Neuronal Cultures

As a tool to investigate the E/I imbalance in synaptopathy models, we will develop methods for the isolation and culturing of pure excitatory and inhibitory neuronal populations from wt mice and mice models of synaptopathies, by immunoisolating inhibitory neurons through anti-Kv3.1b antibodies or by selectively eliminating GABAergic interneurons from mixed cultures by a ribosome inactivation approach through delivery of saporin-conjugated anti-vesicular GABA transporter antibodies. The use of highly enriched glutamatergic and GABAergic neuronal cultures will allow to study their morphological, biochemical and functional differentiation in vitro.



2) Analysis of Excitatory and Inhibitory Synapse Development In Genetic Models Of Synaptopathies

We aim at examining how the formation, stability and plasticity of excitatory versus inhibitory synapses is affected by the elimination of potential synaptopathy gene products or by mutations in synaptopathy genes associated with neurological or psychiatric conditions. We will focus on different experimental models of diseases: SNAP25 (ADHD, schizophrenia), TNIK (ADHD, schizophrenia), Eps8 (intellectual disabilities), neuroligin-3 (autism, collaboration with Unit Cherubini), synapsins (autism, epilepsy, collaboration with Units Benfenati and Valtorta). We will measure the stability and trafficking of reporter pre- and post-synaptic proteins selectively expressed in excitatory or inhibitory neurons and assess possible long term modifications of synapse stability. The analysis will be carried out at resting conditions or upon treatments that lead to increase or inhibition of network activity.



3) Analysis Of Synapse Function and Plasticity in Mice Models Of Schizophrenia, ADHD and Intellectual Disabilities

We will use electrophysiology coupled to confocal analysis to assess, both in culture and in vivo, whether changes in the expression of synaptopathy gene products (SNAP-25, Eps8 and TNIK) affect synapse function, dendritic spine density and morphology, structural and functional synaptic plasticity.



Expected results: all together, results of these studies will help in understanding some of the molecular mechanisms that, impacting on either E/I imbalance or synaptic growth and spine morphology, may be at the basis of different psychiatric diseases such as schizophrenia, ADHD and intellectual disabilities.