# Glutamate Metabotropic Receptors-Linked Postsynaptic Density Proteins: An Emergent Hub for Antipsychotics’ Regulation of Synaptic Plasticity and Metaplasticity

## TL;DR

This paper explores how glutamate receptors and postsynaptic proteins form a key network in regulating brain signaling and how antipsychotics might target this network in schizophrenia.

## Contribution

The paper introduces the concept of a dynamic molecular hub involving mGluRs and PSD proteins as a novel target for antipsychotic therapies.

## Key findings

- Dysregulation of mGluRs and PSD proteins may contribute to schizophrenia by altering glutamatergic transmission.
- Antipsychotics may modulate synaptic plasticity through interactions with mGluRs and PSD proteins.
- Novel agents like SPG302 and allosteric modulators offer new therapeutic strategies for schizophrenia.

## Abstract

Glutamate metabotropic receptors (mGluRs) and their molecular partners at the postsynaptic density (PSD) represent a highly dynamic molecular hub that integrates multiple neurotransmitter signals and regulates synaptic plasticity and metaplasticity, which are putatively involved in the pathophysiology of psychiatric illnesses, including schizophrenia. Group I mGluRs (mGluR1 and mGluR5) interact with PSD adaptor and scaffolding proteins, such as Homer, Shank, Norbin, and PICK1, as well as intracellular downstream effectors, creating a molecular network that resembles a Lego-like structure, where modular protein interactions fine-tune glutamatergic transmission. Evidence from preclinical research indicates that dysregulation of mGluR expression and function, along with disrupted PSD protein expression, may contribute to the pathophysiology of schizophrenia by altering glutamatergic neurotransmission and synaptic stability. Antipsychotic mechanisms of action may involve, at least in part, the modulation of mGluR activity mediated through PSD proteins. Notably, novel agents that enhance spinogenesis by acting at the level of PSD proteins, such as SPG302, may open promising avenues for therapeutics aimed at restoring synaptic integrity. While Group I mGluRs dominate postsynaptic regulation, Group II (mGluR2/3) and III (mGluR4/6/7/8) receptors -primarily presynaptic- inhibit neurotransmitter release and plasticity, offering complementary therapeutic avenues. Emerging strategies, such as allosteric modulators of mGluRs, aim to rebalance synaptic signaling in treatment-resistant schizophrenia. This review synthesizes how PSD proteins and mGluRs interact in schizophrenia, exploring their potential as druggable targets for novel therapies.