microglial activation promoting a trophic “resting” state (Liu et al.). Stress, ethanol, other addictive drugs as well as sensory and hormonal signals activate monocytes and microglia. Cycles of stimuli lead to microglial adaptive conditioning (Shpargel et al. 2008). Interestingly, microglial dysfunction has been discovered to contribute to obsessive-compulsive behaviors (Greer and Capecchi 2002), consistent with microglia contributing to the neurobiology of addiction. Thus, microglia are sensitive to addictive drugs and stress, that lead to progressive adaptation that could alter neurobiology and behavior through innate immune gene induction.
