title: Involvement of RhoA and possible neuroprotective effect of fasudil, a Rho kinase inhibitor, in NMDA-induced neurotoxicity in the rat retina.
abstract: RhoA, a key protein involved in cytoskeleton regulation modulating neurogenesis and neural plasticity, has been implicated in a variety of cellular functions including the modulation of N-methyl-D-aspartate (NMDA) receptor activity. We examined its possible involvement in NMDA-induced excitotoxicity in the retina, and evaluated the neuroprotective effect of fasudil, a Rho kinase inhibitor, in this model of neurotoxicity. RhoA protein levels in NMDA-treated retinas were assessed by Western blot analysis and localized by immunohistochemistry. Fasudil (10(-6)-10(-4) M together with 4 x 10(-2) M NMDA) was given intravitreally and its effect was evaluated by counting the number of cells in the ganglion cell layer (GCL), measuring the thickness of the inner plexiform layer (IPL), and measuring retinal Thy-1 mRNA levels at 5 days after injection. Western blot analysis showed a transient increase in the level of retinal RhoA and ROCKII proteins at 1 day after NMDA injection, and that this increment was significantly prevented by simultaneous injection of fasudil. Immunohistochemistry showed that NMDA induced a substantial increase in RhoA immunoreactivity in the GCL and the IPL. Fasudil injection reduced cell loss in the GCL and the reduction in IPL thickness after NMDA injection. The reduction in Thy-1 mRNA levels by NMDA was also significantly attenuated by concomitant injection of fasudil. These results suggest that RhoA and ROCKII are upregulated and may be involved in NMDA-induced retinal neurotoxicity, and that fasudil is neuroprotective against glutamate-related excitotoxicity.
authors.affiliation: Department of Opthalmology, St Marianna University School of Medicine, Kawasaki-shi, Kanagawa, Japan. kitaoka@marianna_u.ac.jp
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kitaoka
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kitaoka
authors.forename: Toshio
authors.initials: T
authors.lastname: Kumai
authors.forename: Tim T
authors.initials: TT
authors.lastname: Lam
authors.forename: Kohei
authors.initials: K
authors.lastname: Kuribayashi
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Isenoumi
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Munemasa
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Motoki
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Satoki
authors.initials: S
authors.lastname: Ueno
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D002452:Cell Count; D004195:Disease Models, Animal; D004347:Drug Interactions / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009410:Nerve Degeneration / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D009498:Neurotoxins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D012162:Retinal Degeneration / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D018800:Thy-1 Antigens / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D018696:Neuroprotective Agents; D009498:Neurotoxins; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D018800:Thy-1 Antigens; D018698:Glutamic Acid; D016202:N-Methylaspartate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; C049347:fasudil