Mouse hippocampal neurons were isolated and cultured from floxed-GABABR1 mice as described previously.27 (link),46 (link) Cells were cultured in poly-d-lysine-coated (0.1 mg/mL) plastic dishes and/or glass coverslips in a neuron maintenance medium27 (link),46 (link) for 3 days and supplemented with cytosine β-d-arabinofuranoside (3 μmol/L; Sigma, St. Louis, MO, USA) for an additional 3–4 days. These neurons were then infected with adenoviruses (8 pfu/cell) carrying a cDNA encoding Cre recombinase (Ad-Cre; Microbix Inc., Toronto, Canada) or empty viral vector (Ad-Cont Microbix Inc., Toronto, Canada) as described previously.27 (link),46 (link)