Lithium

Lithium inhibits microglial activation via the toll-like receptor 4 (TLR4).

microglia A type of immune cell, called a macrophage, that lives in the brain. For historical reasons, macrophages have different names based on the part of the body that they normally live in. Macrophages that normally live in the blood are called monocytes. Macrophages that normally live in the skin are called Langerhans cells. Macrophages that normally live in the liver are called Kupffer cells. And macrophages that normally live in the central nervous system are called microglia. Microglia were originally classified as glial cells, under the assumption that the cells had a merely structural function, before it was realized that the cells were in fact immune cells. As the "sentinel cells" of the central nervous system, microglia survey their environment for abnormalities such as infection or tissue damage, and then initiate an immune response to fight the infection or repair the tissue damage.