Possible Involvement of Muscarinic Receptors in Psychiatric Disorders: A Focus on Schizophrenia and Mood Disorders

A considerable body of data supports a role for the central cholinergic system in the aetiologies of schizophrenia and mood disorders. There have been breakthroughs in gaining structural data on muscarinic receptors (CHRMs), understanding their role in CNS functioning and in synthesising drugs that can specifically target each of the 5 CHRMs. This means it is opportune to consider the role of specific CHRMs in the pathophysiologies of schizophrenia and mood disorders. This review will focus on data suggesting changes in levels of CHRM1 and CHRM4 implicate these receptors in the pathophysiology of schizophrenia whereas data suggest a role for CHRM2 in mood disorders. There will be a selected reference to recent developments in understanding the roles of CHRM1, 2 and 4 in CNS function and how these predict mechanisms by which these receptors could induce the symptoms prevalent in schizophrenia and mood disorders. Finally, there will be comments on the potential advantages and problems in targeting CHRM1 and CHRM4 to treat the symptoms of schizophrenia and CHRM2 to treat the symptom of depression. Keywords: Acetylcholine, muscarinic receptor, schizophrenia, bipolar disorders, major depressive disorders, neuroinflammation.