Cannabinoid CB2 receptors are expressed by perivascular microglial cells in the human brain: an immunohistochemical study.

Two types of cannabinoid receptors have been characterized so far, CB1 and CB2. While CB1 receptors are present both in the CNS and in the periphery, CB2 receptors showed an almost exclusive distribution within the immune system. We now report that CB2 receptors are present in a specific microglial cell type of the human cerebellum. Thus, we have performed immunohistochemical analysis of tissue sections of white matter areas of the human cerebellum and detected the presence of CB2 receptors in perivascular microglial cells. These findings match with the well-known immunomodulatory role of CB2 receptors and open new perspectives on the possible role that these receptors may play in pathophysiological events.