The Immune System and the Role of Inflammation in Perinatal Depression

Microglia and nerve tissue. A Schematic of the arrangement of interacting neurons, microglia, and astrocytes in the human brain, highlighting two morphological conformations adopted by microglia (resting and active states) in response to incoming insults. Microglia are the primary immune cells of the CNS and, like peripheral macrophages, they act as the major inflammatory cell type (scavengers) that responds to external or internal “stressors” (pathogens, injuries, and life experiences) by becoming “activated” (a process that changes cell morphology and function) and enhancing its own proliferation and migration to the infection or injury site. B Activated microglia secrete pro-inflammatory cytokines and chemokines (MCP-1), together with prostaglandins, nitric oxide, and reactive oxygen species (see Fig. 2C) which regulate and increase the local immune response. Inflammatory cytokines are triggering factors involved in the reduced neurogenesis and neuronal atrophy of granule cells in the dentate gyrus of the hippocampus. This leads to a decrease in hippocampal volume and impairment of hippocampal-related functions, as shown in MDD