Activation of the mGlu5 Receptor for the Treatment of Schizophrenia and Cognitive-Deficit-Associated Disorders

mGlu5 receptors have been implicated in the pathophysiology of schizophrenia and cognitive dysfunction, and activation of these receptors has been proposed as a potential therapeutic strategy for treating these diseases. This chapter describes the recent progress in the discovery and development of mGlu5 positive allosteric modulators (PAMs) as a novel therapeutic approach which does not involve a direct interaction with dopamine receptors. This new class of molecules is structurally very diverse and includes several drug-like chemical series. The pharmacological activity shown by these molecules in preclinical studies confirms their therapeutic potential in all domains of schizophrenia, including positive and negative symptoms and cognitive abnormalities. These data support the development of mGlu5 PAMs as novel antipsychotic drugs that resonate with the glutamatergic hypofunction hypothesis of schizophrenia. The fine tuning of the functional activity and the clarification of biased signaling pathways in different chemical series may provide clues to achieve efficacy and a good safety profile for novel pharmacotherapies.