TSPO and fibromyalgia: The glial mechanism in patients: Using Positron Emission Tomography with a radioligand (11)C-PBR28 that binds to the translocator protein (TSPO), a protein unregulated in activated microglia and astrocytes in the brain, studies have probed microglia and astrocyte activation in patients with lower back pain, fibromyalgia, and rheumatoid arthritis [177,178,179,180].