Blocking of [18F]7a and [18F]7c with α7-nAChR – selective ligands in CD-1 mice. Left panel: Dose dependent blockade of [18F]7a (0.07 mCi, specific radioactivity = 7900 mCi/µmol, i.v.) accumulation by intravenous co-injection with 1 (doses 0.02 mg/kg, 0.2 mg/kg, 1 mg/kg, 3 mg/kg) in the mouse brain regions 90 min after the injection. *P ≤ 0.01, significantly different from controls (ANOVA). Right panel: Dose dependent blockade of [18F]7c (0.07 mCi, specific radioactivity = 11000 mCi/µmol, i.v.) accumulation by intravenous co-injection with 5 (doses 0.001 mg/kg, 0.0045 mg/kg, 0.014 mg/kg) in the mouse brain regions 90 min after the injection. *P < 0.01, significantly different from controls; and **P = 0.06, insignificantly different from control (ANOVA). Data: mean %injected dose/g tissue ± SD (n=3). Abbreviations: Coll = superior and inferior colliculus; Hipp = hippocampus; Ctx = cortex; Str = striatum; Th = thalamus; Rest = rest of brain; CB = cerebellum.