title: Ammonia-induced brain swelling and neurotoxicity in an organotypic slice model.
abstract: OBJECTIVE
  Acute liver failure (ALF) produces cerebral dysfunction and edema, mediated in part by elevated ammonia concentrations, often leading to coma and death. The pathophysiology of cerebral edema in ALF is incompletely understood. In vitro models  of the cerebral effects of ALF have predominately consisted of dissociated astrocyte cultures or acute brain slices. We describe a stable long-term culture model incorporating both neural and glial elements in a three-dimensional tissue structure offering significant advantages to the study  of astrocytic-neuronal interactions in the pathophysiology of cerebral edema and dysfunction in ALF.
  
  
  METHODS
  We utilized chronic organotypic slice cultures from mouse forebrain, applying ammonium acetate in iso-osmolar fashion for 72 hours. Imaging of slice thickness to assess  for tissue swelling was accomplished in living slices with optical coherence tomography, and confocal microscopy of fluorescence immunochemical and histochemical staining served to assess astrocyte and neuronal numbers, morphology, and volume in the fixed brain slices.
  
  
  RESULTS
  Ammonia  exposure at 1-10 mM produced swelling of immunochemically identified astrocytes, and at 10 mM resulted in macroscopic tissue swelling, with slice thickness increasing by about 30%. Astrocytes were unchanged in number. In contrast, 10 mM ammonia treatment severely disrupted neuronal  morphology and reduced neuronal survival at 72 hours by one-half.
  
  
  CONCLUSIONS
  Elevated ammonia produces astrocytic swelling, tissue swelling, and neuronal toxicity in cerebral tissues. Ammonia-treated organotypic brain slice cultures provide an In vitro model of cerebral effects  of conditions relevant to ALF, applicable to pathophysiological investigations.
authors.affiliation: Department of Surgery, The University of Chicago,IL 60637, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Back
authors.forename: Kelsey Y
authors.initials: KY
authors.lastname: Tupper
authors.forename: Tao
authors.initials: T
authors.lastname: Bai
authors.forename: Paulpoj
authors.initials: P
authors.lastname: Chiranand
authors.forename: Fernando D
authors.initials: FD
authors.lastname: Goldenberg
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Frank
authors.forename: James R
authors.initials: JR
authors.lastname: Brorson
mesh_terms: D000641:Ammonia / Q000633:toxicity*; D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D001929:Brain Edema / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D004195:Disease Models, Animal; D006501:Hepatic Encephalopathy / Q000473:pathology / Q000503:physiopathology*; D022124:Hyperammonemia / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009410:Nerve Degeneration / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D009924:Organ Culture Techniques
chemical_list: D000641:Ammonia