Brain Imaging of Sigma Receptors

Abstract Imaging of sigma receptors in the living human brain is of interest because these receptors are potent targets for the treatment of neurological and neuropsychiatric diseases and brain ischemia. A number of radioligands have been developed for the imaging of sigma receptors, and a few, including [ 11 C]SA4503, have been used in clinical studies for imaging in the human brain. The sigma 1 receptor is distributed throughout the human brain. A widespread decrease in [ 11 C]SA4503 binding in patients with Alzheimer's disease and a significant decrease in binding on the more affected side of the anterior putamen in patients with Parkinson's disease have been found. Drug-loading [ 11 C]SA4503-positron emission tomography studies using therapeutic drugs for neurological and neuropsychiatric disorders have shown that some of the drugs had an affinity for sigma 1 receptors in the human brain in addition to their main targets.