title: Retinal ganglion cell neuroprotection by an angiotensin II blocker in an ex vivo retinal explant model.
abstract: OBJECTIVE
  An ex vivo organotypic retinal explant model was developed to examine retinal survival mechanisms relevant to glaucoma mediated by the renin angiotensin system in the rodent eye.
  
  
  METHODS
  Eyes from adult Sprague Dawley rats were enucleated immediately post-mortem and used to make four retinal explants per eye. Explants were treated either with irbesartan (10 µM), vehicle or angiotensin II (2 μM) for four days. Retinal ganglion cell density was estimated by βIII tubulin immunohistochemistry. Live imaging of superoxide formation with dihydroethidium (DHE) was performed. Protein expression was determined by Western blotting, and mRNA expression was determined by RT-PCR.
  
  
  RESULTS
  Irbesartan (10 µM) almost doubled ganglion cell survival after four days. Angiotensin II (2 µM) reduced cell survival by 40%. Sholl analysis suggested that irbesartan improved ganglion cell dendritic arborisation compared to control and angiotensin II reduced it. Angiotensin-treated explants showed an intense DHE fluorescence not seen in irbesartan-treated explants. Analysis of protein and mRNA expression determined that the angiotensin II receptor At1R was implicated in modulation of the NADPH-dependent pathway of superoxide generation.
  
  
  CONCLUSIONS
  Angiotensin II blockers protect retinal ganglion cells in this model and may be worth further investigation as a neuroprotective treatment in models of eye disease.
authors: Centre for Vision Research, Westmead Millennium Institute, University of Sydney, Australia Cambridge NIHR Biomedical Research Centre, UK andrew.white@sydney.edu.au.
authors: Andrew J R
authors: AJ
authors: White
authors: John van Geest Centre for Brain Repair, University of Cambridge, UK.
authors: Janosch P
authors: JP
authors: Heller
authors: School of Medical Sciences, Discipline of Physiology, University of Sydney, Australia.
authors: Johahn
authors: J
authors: Leung
authors: John van Geest Centre for Brain Repair, University of Cambridge, UK.
authors: Alessia
authors: A
authors: Tassoni
authors: John van Geest Centre for Brain Repair, University of Cambridge, UK Cambridge NIHR Biomedical Research Centre, UK Wellcome Trust - MRC Cambridge Stem Cell Institute, University of Cambridge, UK.
authors: Keith R
authors: KR
authors: Martin
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology*; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D015153:Blotting, Western; D002452:Cell Count; D003712:Dendrites / Q000187:drug effects; D021621:Imaging, Three-Dimensional; D000077405:Irbesartan; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008954:Models, Biological; D009249:NADP / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D000066829:Neuroprotection / Q000187:drug effects*; D021122:Protein Subunits / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D044139:Receptor, Angiotensin, Type 2 / Q000235:genetics / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000166:cytology*; D013194:Staining and Labeling; D013777:Tetrazoles / Q000494:pharmacology
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D001713:Biphenyl Compounds; D008562:Membrane Glycoproteins; D021122:Protein Subunits; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles; D000804:Angiotensin II; D009249:NADP; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D000077405:Irbesartan
keywords: Neuroprotection; angiotensin; glaucoma; retinal explant