Module 7: Figure microglia interactions
Microglial surveillance and activation functions.
Microglial cells have two main functional states: surveillance and activation phases. During their surveillance mode (shown on the left) long fine processes monitor the environment and respond to many different stimuli such as pathogens and serum factors that invade the brain from ruptured blood vessels, abnormal proteins such as the β-amyloid and neurotransmitters released from the neurons. These different stimuli activate the microglia that then release a wide range of stimuli such as chemokines, trophic factors, cytokines and prostaglandins. Many of these stimuli act in an autocrine manner to feedback on to the microglia or they have a paracrine function by acting on the neurons or astrocytes. See text for further details and a description of the abbreviations.