title: Synthesis and evaluation of (13)N-labelled azo compounds for β-amyloid imaging in mice.
abstract: OBJECTIVE
  The aim of the present study was to develop short half-lived tools for in vitro and in vivo β-amyloid imaging in mice, for which no suitable PET tracers are available.
  
  
  METHODS
  Five (13)N-labelled azo compounds (1-5) were synthesized using a three-step process using cyclotron-produced [(13)N]NO3 (-). Biodistribution studies were performed using positron emission tomography-computed tomography (PET-CT) on 20-month-old healthy, wild-type (WT) mice. In vivo and in vitro binding assays were performed using PET-CT and autoradiography, respectively, on 20-month-old healthy (WT) mice and transgenic (Tg2576) Alzheimer's disease model mice.
  
  
  RESULTS
  (13)N-labelled azo compounds were prepared with decay corrected radiochemical yields in the range 27 ± 4 % to 39 ± 4 %. Biodistribution studies showed good blood-brain barrier penetration for compounds 1 and 3-5; good clearance data were also obtained for compounds 1-3 and 5. Compounds 2, 3 and 5 (but not 1) showed a significant uptake in β-amyloid-rich structures when assayed in in vitro autoradiographic studies. PET studies showed significant uptake of compounds 2 and 3 in the cortex of transgenic animals that exhibit β-amyloid deposits.
  
  
  CONCLUSIONS
  The results underscore the potential of compounds 2 and 3 as in vitro and in vivo markers for β-amyloid in animal models of Alzheimer's disease.
authors: Radiochemistry Department, Molecular Imaging Unit, CIC biomaGUNE, San Sebastian, Spain.
authors: Vijay
authors: V
authors: Gaja
authors: Vanessa
authors: V
authors: Gómez-Vallejo
authors: Maria
authors: M
authors: Puigivila
authors: Carlos
authors: C
authors: Pérez-Campaña
authors: Abraham
authors: A
authors: Martin
authors: Ana
authors: A
authors: García-Osta
authors: Teresa
authors: T
authors: Calvo-Fernández
authors: Mar
authors: M
authors: Cuadrado-Tejedor
authors: Rafael
authors: R
authors: Franco
authors: Jordi
authors: J
authors: Llop
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D001391:Azo Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D006624:Hippocampus / Q000000981:diagnostic imaging; D008024:Ligands; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009587:Nitrogen Isotopes; D049268:Positron-Emission Tomography / Q000379:methods*; D014018:Tissue Distribution
chemical_list: D016229:Amyloid beta-Peptides; D001391:Azo Compounds; D008024:Ligands; D009587:Nitrogen Isotopes