The mitochondrial translocator protein (TSPO): a key multifunctional molecule in the nervous system

Translocator protein (TSPO, 18 kDa), formerly known as peripheral benzodiazepine recep-tor, is an evolutionary well-conserved protein located on the outer mitochondrial mem-brane. TSPO is involved in a variety of fundamental physiological functions and cellular processes. Its expression levels are regulated under many pathological conditions, there-fore, TSPO has been proposed as a tool for diagnostic imaging and an attractive thera-peutic drug target in the nervous system. Several synthetic TSPO ligands have thus been explored as agonists and antagonists for innovative treatments as neuroprotective and regenerative agents. In this review, we provide state-of-the-art knowledge of TSPO func-tions in the brain and peripheral nervous system. Particular emphasis is placed on its contribution to important physiological functions such as mitochondrial homeostasis, energy metabolism and steroidogenesis. We also report how it is involved in neuroinflam-mation, brain injury and diseases of the nervous system.