Neurobiological Mechanisms of Maternal Immune Activation-Induced Neurodevelopmental Disorders: A Serotonin Model

Serotonin (5-HT) is a significant regulator of neurodevelopment and behavior. Any perturbation in 5-HT system during pre- or early postnatal brain development has been established as a causative factor for the emergence of neurodevelopmental disorders, such as autism spectrum disorders (ASDs) and schizophrenia. Maternal immune activation (MIA) during pregnancy can alter the 5-HT system, leading to emergence of these disorders. The exact molecular mechanism by which MIA induces changes in the 5-HT system to cause neurodevelopmental disorders is not well understood. The SERT gene which codes for the serotonin transporter has been implicated in ASDs. Additionally, transiently SERT-expressing neurons have been identified in various brain areas during development, and their disruption has been linked to derailing of cortical synaptic architectural trajectory, leading to persistent alterations in cortical circuits. The disruption of the 5-HT system and along with transiently SERT-expressing neuronal system, particularly during critical periods of brain development, is a likely cause of diverse autistic features. Understanding the precise mechanisms by which alterations in serotonin levels lead to ASDs could help in the development of targeted therapies to mitigate the impact of these disorders.