Article Figures & Data
Figures
- FIGURE 1.
Chemical structures of 11C-Me-NB1, PF-Me-NB1, and OF-Me-NB1.
- FIGURE 2.
Representative in vitro autoradiograms with 11C-labeled probes on coronal rat and mouse brain sections. (A) Para-fluorinated derivatives (R)- and (S)-11C-PF-Me-NB1 revealed binding across all rat brain regions, with cerebellum showing highest accumulation. (B) Ortho-fluorinated derivatives (R)- and (S)-11C-OF-Me-NB1 exhibited distinct binding patterns. Although (S)-enantiomer distributed uniformly across all rat brain regions, (R)-enantiomer revealed high selectivity for GluN2B-expressing forebrain regions. (C) Distinct binding patterns of (R)- and (S)-11C-OF-Me-NB1 were further confirmed on mouse brain sections. Blocker screening revealed GluN2B specificity for (R)-enantiomer and considerable σ1R binding of (S)-enantiomer.
- FIGURE 3.
(A) Synthesis of (R)-18F-OF-Me-NB1 using copper-mediated radiofluorination and subsequent deacetylation under basic conditions. (B) Representative in vitro autoradiographic blocker screening in rat brain sections with GluN2B ligands (CP101,606, EVT 101) and σ1R ligands (SA4503, fluspidine, (+)-pentazocine). Cb = cerebellum; CPu = caudate putamen (striatum); Cx = cortex; Hp = hippocampus; Th = thalamus.
- FIGURE 4.
Dose-dependent blocking of (R)-18F-OF-Me-NB1 binding by GluN2B antagonist CP101,606 in Wistar rat brain in vivo and respective calculated receptor occupancy. (A) Time–activity curves for baseline and blockade experiments with escalating injected doses of CP101,606 (0.1–10 mg/kg) are presented as SUVs. (B) Receptor occupancy for each CP101,606 dose calculated from area under curve of SUVs (SUV0–90 min). (C) PET images of rat brain superimposed on PMOD MRI template under baseline and blockade conditions with GluN2B antagonist CP101,606. Images were averaged from 0 to 90 min after injection. Bs = brain stem; Cb = cerebellum; CPu = caudate putamen (striatum); Cx = cortex; Hp = hippocampus; Th = thalamus.
- FIGURE 5.
Radio-UPLC analysis of Wistar rat brain extracts. Final tracer formulation after radiosynthesis is depicted, as well as brain samples at 15, 30, and 60 min after injection.
- FIGURE 6.
Time–activity curves in different brain regions of Wistar rat are presented as SUVs. Specificity of (R)-18F-OF-Me-NB1 binding was confirmed by injection of GluN2B antagonists CP101,606 (3 mg/kg) and eliprodil (2 mg/kg) shortly before radioligand injection. One rat was scanned for each condition.
- FIGURE 7.
PET study of (R)-18F-OF-Me-NB1 in σ1R-KO and wild-type (WT) mice. For blockade experiments, 2 mg/kg dose of commercially available GluN2B antagonist eliprodil was used. (A) Coronal PET images, averaged from 1 to 90 min after injection, superimposed on MRI template (PMOD). Shown are WT baseline (upper left), WT eliprodil blockade (upper right), σ1R-KO baseline (lower left), and σ1R-KO eliprodil blockade (lower right). (B) Brain time–activity curves are presented as SUV ± SD. Baseline scans were performed on 3 mice and blockade scans on 1 mouse. Cb = cerebellum; CPu = caudate putamen (striatum); Cx = cortex; Hp = hippocampus; Th = thalamus.
Tables
Time (min) (R)-18F-OF-Me-NB1 (%) Radiometabolites (%) 0 100 0 5 86 14 15 76 24 30 71 29 45 52 48 60 45 55 Fractions of intact parent tracer and radiometabolites in plasma are depicted as percentage of total radioactivity.
Supplemental Data
Files in this Data Supplement:
