title: Involvement of glial cells in the autoregulation of optic nerve head blood flow in rabbits.
abstract: OBJECTIVE
  To investigate the involvement of glial cells in the autoregulation of optic nerve head (ONH) blood flow in response to elevated intraocular pressure (IOP).
  
  
  METHODS
  Rabbit eyes were treated with an intravitreal injection of l-2-aminoadipic acid (LAA), a gliotoxic compound. Twenty-four hours after the injection IOP was artificially elevated from a baseline of 20 to 50 or 70 mm Hg and maintained at each IOP level for 30 minutes. ONH blood flow was measured by laser speckle flowgraphy every 10 minutes. Ocular perfusion pressure (OPP) was calculated to investigate the relationship between ONH blood flow and OPP. To evaluate the effects of LAA on the function and morphology of retinal neurons and glial cells, electroretinogram (ERG) was monitored after injections of LAA (2.0 and 6.0 mM) or saline as a control. Histologic and immunohistochemical examinations were then performed.
  
  
  RESULTS
  In the LAA-treated eyes, histologic changes selectively occurred in the retinal Müller cells and ONH astrocytes. There was not any significant reduction of amplitude or elongation of implicit time of each parameter in the ERG after LAA injection compared with control. ONH blood flow in LAA-treated eyes was significantly decreased with a reduction of OPP during IOP elevation to 50 and 70 mm Hg, whereas blood flow was maintained in control eyes during IOP elevation to 50 mm Hg.
  
  
  CONCLUSIONS
  These results indicate the involvement of glial ells in the autoregulation of ONH blood flow during IOP elevation.
authors.affiliation: Department of Ophthalmology, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Maho
authors.initials: M
authors.lastname: Shibata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Takuji
authors.initials: T
authors.lastname: Kurimoto
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Oku
authors.forename: Takashi
authors.initials: T
authors.lastname: Okuno
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Ikeda
mesh_terms: D015074:2-Aminoadipic Acid / Q000494:pharmacology; D000818:Animals; D016022:Case-Control Studies; D004596:Electroretinography; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D009457:Neuroglia / Q000187:drug effects / Q000502:physiology*; D009798:Ocular Hypertension / Q000503:physiopathology*; D009898:Optic Disk / Q000098:blood supply*; D011817:Rabbits; D012039:Regional Blood Flow / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D015074:2-Aminoadipic Acid