XBD173 (emapunil, AC-5216) is a potent and selective translocator protein 18 kDa (TSPO) ligand with a Ki value of 0.297 nM. XBD173 acts at the TSPO translocator protein, formerly called the peripheral benzodiazepine receptor, which is involved in production of neuroactive steroids such as allopregnanolone in the brain. TSPO carries cholesterol from the outer to the inner mitochondrial membrane, which is the rate-limiting step of steroidogenesis. XBD173 enhances GABA-mediated neurotransmission via induction of neurosteroidogenesis and exhibits anti-anxiety and antidepressant-like effects.
