Blocking studies of 18
F-SIG343 and 18
F-SIG353. Blocking studies of 18F-SIG343 (a) and 18F-SIG353 (b) in the presence of competing σ2 ligands: haloperidol, unlabelled SIG343 or SIG353 (1 mg/kg), respectively. Results were expressed as radioconcentration of the tracers in the organs in the treatment group compared to controls (means ± SEM, n = 5). *P <0.001 drug treatment versus control (within-group two-way ANOVAs (treatment × regions), followed by Bonferroni's post hoc tests).