TSPO and alcohol dependence: TSPO is also expressed in other central nervous system cell types, including activated astrocytes, endothelium and blood components such as acute phase proteins.27, 28, 29 Increased TSPO expression has been demonstrated pre-clinically using [3H]PK11195 autoradiography in chronic alcohol intake24 and withdrawal models.19, 26 [11C]PK11195 binding was increased in a small clinical cohort with hepatic encephalopathy,30 three members of which had a history of alcohol dependence, though they were long abstinent.