Microglial Activation in the Neurodevelopment: A Narrative Review

Microglia are immune cells found in the central nervous system (CNS) involved in infection combat and cellular debris clean. These glial cells are involved in synaptogenesis during brain development by their interactions with neurons and other glial cells. These relations are associated with the secretion of signaling molecules, such as chemokines and neurotrophic factors. Microglia cells influence synapsis and neuron morphology during different phases of development. Also, other systems, for example, gut microbiota, indirectly affect microglial functions and morphology. Several factors that can occur in different development periods, including intrauterine through adult life, could impact microglia. Impairment in these cells could be associated with the development of some psychiatric conditions, such as schizophrenia, autistic spectrum disorder (ASD), and depression. This review focuses on describing microglia functions in the maintenance of CNS and how they are associated with other systems, as the gut-microbiota brain axis and environmental stressors, such as stress, maternal deprivation, sleep deprivation, immune activation, and ethanol exposure, that can influence the function of the microglia during neurodevelopment.