title: Aquaporin-4 positron emission tomography imaging of the human brain: first report.
abstract: OBJECTIVE
  Aquaporin 4 (AQP-4) is the most abundant aquaporin isoform in the brain. Alterations in its expression and distribution have been correlated with the progression of several clinical disorders; however, the specific roles of AQP-4 in those disorders are not well understood. Visualizing AQP-4 in vivo is expected to provide fresh insights into its roles in disease pathology, as well as aiding the clinical assessment of those disorders.
  
  
  METHODS
  We developed a 11C-labeled analogue of the AQP-4 ligand TGN-020 (2-nicotinamido-1,3,4-thiadiazole) suitable for in vivo positron emission tomography (PET) imaging.
  
  
  RESULTS
  In the present study, we report the first PET images of AQP-4 in the human brain. The results unequivocally demonstrated a specific distribution pattern for AQP-4 within the brain, namely, the subpial and perivascular endfeet of astrocytes. The choroid plexus, where both AQP-4 and AQP-1 are expressed, also showed substantial uptake of the ligand.
  
  
  CONCLUSIONS
  Based on these initial results, we believe [11C]TGN-020 PET will be valuable in determining the role of AQP-4 in disease progression, and for the clinical assessment of water homeostasis under various settings.
authors: Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata.
authors: Yuji
authors: Y
authors: Suzuki
authors: Yukihiro
authors: Y
authors: Nakamura
authors: Kenichi
authors: K
authors: Yamada
authors: Vincent J
authors: VJ
authors: Huber
authors: Mika
authors: M
authors: Tsujita
authors: Tsutomu
authors: T
authors: Nakada
mesh_terms: D000328:Adult; D000818:Animals; D051401:Aquaporin 4 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000633:toxicity; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013830:Thiadiazoles / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: C558003:2-(nicotinamide)-1,3,4-thiadiazole; C496030:AQP4 protein, human; D051401:Aquaporin 4; D019275:Radiopharmaceuticals; D013830:Thiadiazoles; D009536:Niacinamide