Nepicastat Modulation of Dopamine Homeostasis

Nepicastat was administered to Dbh +/− mice via daily i.p. injections (western blots) or osmotic minipumps (locomotor activity). For the i.p. administration, Dbh +/− mice received vehicle or nepicastat (50 mg/kg, i.p. × 3, each injection spaced 2 h apart) for 5 consecutive days. This dosing regimen reduces brain NE levels by ~ 75% and produces cocaine hypersensitivity (Gaval-Cruz et al., 2012 (link)). Mice were euthanized by CO₂ asphyxiation 11 days later, and their brains were removed, dissected on ice, and stored at −80°C. For the minipump administration, nepicastat was dissolved in 50% saline and 50% DMSO and loaded into Alzet osmotic minipumps (Model #2004, 0.25μL/hour, 28 days; Durect, Cupertino, CA) to achieve a dose of 50 mg/kg/d. All pumps were placed in a sterile 37°C saline bath for 1 d before implantation. Mice were anesthetized with isoflurane, and minipumps implanted in the intraperitoneal cavity. Buprenorphine (2.5mg/kg, s.c.) was given immediately after surgery. Cocaine-induced locomotion was recorded 21 d after pump implantation.