Involvement of RhoA and possible neuroprotective effect of fasudil, a Rho kinase inhibitor, in NMDA-induced neurotoxicity in the rat retina

• Published in: Brain research Vol. 1018; no. 1; pp. 111 - 118
• Main Authors: Kitaoka, Yuka, Kitaoka, Yasushi, Kumai, Toshio, Lam, Tim T, Kuribayashi, Kohei, Isenoumi, Kazuyuki, Munemasa, Yasunari, Motoki, Masamitsu, Kobayashi, Shinichi, Ueno, Satoki
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 20-08-2004; Amsterdam Elsevier; New York, NY
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - analogs & derivatives; 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - pharmacology; Animals; Biological and medical sciences; Cell Count; Disease Models, Animal; Drug Interactions - physiology; Enzyme Inhibitors - pharmacology; Fasudil; Glutamic Acid - metabolism; Intracellular Signaling Peptides and Proteins; Male; Medical sciences; N-Methyl- d-aspartate; N-Methylaspartate - pharmacology; Nerve Degeneration - drug therapy; Nerve Degeneration - enzymology; Nerve Degeneration - genetics; Neurons - drug effects; Neurons - metabolism; Neuropharmacology; Neuroprotective agent; Neuroprotective Agents - pharmacology; Neurotoxins - metabolism; Pharmacology. Drug treatments; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Serine-Threonine Kinases - drug effects; Protein-Serine-Threonine Kinases - metabolism; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate - drug effects; Receptors, N-Methyl-D-Aspartate - metabolism; Retina; Retina - drug effects; Retina - enzymology; Retina - physiopathology; Retinal Degeneration - drug therapy; Retinal Degeneration - enzymology; Retinal Degeneration - genetics; Retinal Ganglion Cells - cytology; Retinal Ganglion Cells - drug effects; Retinal Ganglion Cells - enzymology; Rho kinase inhibitor; rho-Associated Kinases; RhoA; rhoA GTP-Binding Protein - metabolism; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Thy-1 Antigens - genetics; Thy-1 mRNA; Up-Regulation - drug effects; Up-Regulation - genetics; Rho kinase inhibitor; Retina; N-Methyl- d-aspartate; Neurotransmitters, modulators, transporters, and receptors; RhoA; Fasudil; Thy-1 mRNA; Rat; Enzyme; Transferases; N-Methyl-D-aspartate; Rodentia; Enzyme inhibitor; Neuroprotective agent; Eye; Visual system; Vertebrata; Neurotoxicity; Mammalia; Kinase; Animal; NMDA
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2004.05.070

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 4×10
−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.