The guide cannula was permanently fixed to the skull with stainless steel screws and methacrylate cement. Experiments were performed 4 days after implantation. The correct placement of guide cannulae was verified by histological

examination of tissue sections. Data from rats in which placements were not localized in the intended site were not included in any analyses. PKG activation and overexpression For PKG overexpression, plasmid/polyethyleneimine (PEI) complexes were injected into the CPu (2 μL) or VTA (0.6 μL), as indicated above. After being complexed with PEI in 5% glucose solution, a p513 vector (7.5 μg) containing the human PKG-Iα cDNA and vector lacking a cDNA Trichostatin A solubility dmso insert were injected into the right hemi-structure and Inhibitors,research,lifescience,medical left hemi-structure, respectively, Inhibitors,research,lifescience,medical as described previously (Jouvert et al. 2004). PKG was activated by the subsequent injection of a 20 mmol/L 8-bromo-cyclic GMP (Br-cG; Sigma-Aldrich, St Louis, Missouri) in a saline solution, or inhibited by the injection under identical conditions of a 2 mmol/L KT5823 (Calbiochem, Merck, Darmstadt, Germany) solution, according to the schedule

shown in Figure 1. Inhibitors,research,lifescience,medical The injection volume was 0.5 μL for the VTA and 1 μL for the CPu. Control microinjections were equivalent volumes of vehicle. Cocaine (Cooper, Melun, France) was injected intraperitoneally at the dose of 20 mg/kg. Figure 1 Schematic representation of the injection schedule used for PKG overexpression. Rats were given injections of a vector containing the PKG-I cDNA (0.5 μg) into the right VTA (0.6 μL) or CPu (2 μL) and of 0.5 μg of vector … Immunohistochemistry Animals were given an overdose of pentobarbital Inhibitors,research,lifescience,medical (100 mg/kg, intraperitoneally) 45 min following cocaine injection and were then perfused transcardially with 100 mL saline followed by 2% paraformaldehyde in phosphate-buffered saline (PBS; 0.1 mol/L; pH 7.2; 250 mL). The brains were removed, kept overnight at 4°C in 15% sucrose, frozen in isopentane at −40°C, and stored at −80°C. Coronal Inhibitors,research,lifescience,medical sections (20 μm thick) were obtained using a Microm HM560 cryostat. Immunohistochemistry was performed as described previously (Cassel et al. 2006). Briefly, brain

sections were incubated with the following primary polyclonal antibodies: anti-MeCP2 (1:150 dilution; Millipore, Billerica, MA) or anti-HDAC2 (1:200 dilution, Millipore). Sections mafosfamide were then successively incubated with biotinylated donkey anti-rabbit IgG (1:200 dilution) and with an avidin–biotin–peroxidase complex (Vectastain ABC kit, Vector Laboratories, Burlingame, CA). Staining was revealed with the chromagen 3,3′-diaminobenzidine tetrahydrochloride and H2O2. Sections were then incubated in a 2.5 μmol/L bisbenzimide (Hoechst 33258; Sigma-Aldrich) solution to label nuclei and the slides were coverslipped with Mowiol. Staining was observed under a fluorescent Leitz DM RB binocular microscope (Leica Microsystems, Wetzlar, Germany).