[I-125]IodoDPA-713 [I-125]1, which targets the translocator protein (TSPO, 18 kDa), was synthesized in seven steps from methyl-4-methoxybenzoate as a tool for quanti. cation of inflammation in preclinical models. Preliminary in vitro autoradiography and in vivo small animal imaging were performed using [I-125]1 in a neurotoxicant-treated rat and in a murine model of lung inflammation, respectively. The radiochemical yield of [I-125]1 was 44 +/- 6% with a specific radioactivity of 51.8 GBq/mu mol (1400 mCi/mu mol) and >99% radiochemical purity. Preliminary studies showed that [I-125]1 demonstrated increased specific binding to TSPO in a neurotoxicant-treated rat and increased radiopharmaceutical uptake in the lungs of an experimental inflammation model of lung inflammation. Compound [I-125]1 is a new, convenient probe for preclinical studies of TSPO activity. (C) 2009 Elsevier Inc. All rights reserved.