title: Differential effects of LY294002 and wortmannin on neurons and vascular endothelial cells in the rat retina.
abstract: BACKGROUND
  Neuronal damage leads to capillary degeneration in an N-methyl-D-aspartate (NMDA)-induced retinal degeneration model; however, the mechanisms underlying this phenomenon are not fully understood. The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway has been recognized as an intracellular pro-survival signaling system. Therefore, we used the PI3K inhibitors LY294002 and wortmannin to investigate the role of this pathway in neuronal and blood vessel injury in the rat retina treated with NMDA.
  
  
  METHODS
  Male Sprague-Dawley rats weighing 220-240 g were used in this study. NMDA combined with LY294002, wortmannin, or vehicle was administered intravitreally, and histological evaluation was performed at 2 and 7 days after injection. The effects of LY294002 or wortmannin alone were also evaluated.
  
  
  RESULTS
  The number of cells in the ganglion cell layer (GCL) was significantly reduced at 2 and 7 days after intravitreal injection of NMDA, whereas enhanced capillary degeneration was observed at 7 days. Simultaneous injection of LY294002 with NMDA significantly attenuated NMDA-induced retinal cell loss and capillary degeneration at 7 days. However, simultaneous injection of wortmannin with NMDA did not affect cell loss, but enhanced capillary degeneration. Treatment with LY294002 alone showed no effect on neuronal or vascular cells, whereas wortmannin induced capillary degeneration without significantly affecting the cell number in the GCL.
  
  
  CONCLUSIONS
  Although both LY294002 and wortmannin are known as PI3K inhibitors, they exhibit differential effects on neurons and vascular endothelial cells in the rat retina. Therefore, the results obtained using these inhibitors should be carefully interpreted. However, our finding that LY294002 was protective against NMDA-induced retinal damage suggests that this compound may be an effective candidate for preventing the development of retinal diseases associated with glutamate-induced excitotoxicity.
authors.affiliation: Department of Molecular Pharmacology, Kitasato University, School of Pharmaceutical Sciences, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan. nakaharat@pharm.kitasato-u.ac.jp.
authors.forename: Kaori
authors.initials: K
authors.lastname: Ueda
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakahara
authors.forename: Kaori
authors.initials: K
authors.lastname: Akanuma
authors.forename: Asami
authors.initials: A
authors.lastname: Mori
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Kunio
authors.initials: K
authors.lastname: Ishii
mesh_terms: D000730:Androstadienes / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D002452:Cell Count; D002867:Chromones / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D042783:Endothelial Cells / Q000187:drug effects* / Q000473:pathology; D058449:Intravitreal Injections; D008297:Male; D009025:Morpholines / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000633:toxicity; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D012162:Retinal Degeneration / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000473:pathology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D009025:Morpholines; D047428:Protein Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D016202:N-Methylaspartate; D000077191:Wortmannin