Radioligands for the PET Imaging of Metabotropic Glutamate Receptor Subtype 5 (mGluR5)

Metabotropic glutamate receptors (mGluRs) are G-protein coupled receptors (GPCR), which activate intracellular secondary messenger systems when bound by the physiological ligand glutamate. Modulation of mGluR5s has potential for the treatment of variety of psychiatric and neurological diseases such as depression, anxiety, schizophrenia and Parkinson's disease. Positron emission tomography (PET) might offer the possibility to visualize the mGluR5 and present an interesting tool for studying this receptor-subtype under physiologic and pathologic conditions. In this review paper, emphasis is given to the radiosynthesis, in vitro and in vivo characterization of recently published mGluR5 PET tracers.