Prenatal-induced psychopathologies: All roads lead to microglia

The prenatal environment represents an intersection of genetic and environmental interactions with the capability of protecting or predisposing the offspring’s brain to psychopathologies and neurodevelopmental disorders. Healthy brain development requires the cooperation of the immune system in the central nervous system. In this chapter, we describe animal models of maternal-immune overactivation, chronic stress, and adverse maternal lifestyle factors focusing on the activation of microglia. Microglia are the main glial cells responsible for phagocytosis in the brain. Microglia affect synapse formation, pruning, and maturation, influencing neurotransmission/excitatory-inhibitory tone, thus keeping neural homeostasis and modulating neuronal function. Thus, microglial activation can contribute to altered development and prime for future alterations. We illustrate that the stage of development in which microglial activation occurs influences both the structural alterations and the phenotypic outcome that may range from ASD-like or schizophrenia-like phenotypes to depressive-like behaviors and cognitive deficits.