Y-27632, a Rho-associated protein kinase inhibitor, attenuates neuronal cell death after transient retinal ischemia.
OBJECTIVE
Transient retinal ischemia induces the death of retinal neuronal cells. Postischemic damage is associated with the infiltration of leukocytes into the neural tissue through vascular endothelia. The current study aimed to investigate whether this damage was attenuated by the inhibition of Rho/ROCK (Rho kinases) signaling, recently shown to play a critical role in the transendothelial migration of leukocytes.


METHODS
Y-27632, a selective inhibitor of ROCK, was injected intravitreally into rat eyes with transient retinal ischemia. Cell loss of the ganglion cell layer (GCL) and thinning of the inner plexiform layer (IPL) with and without the administration of Y-27632 were evaluated by histological analysis, TUNEL assay and retrograde labeling of retinal ganglion cells (RGCs). To examine the attenuation of leukocyte infiltration in postischemic retinas with the administration of Y-27632, silver nitrate staining and immunohistochemistry using an anti-LCA antibody were performed.


RESULTS
Cell loss of the GCL and thinning of the IPL were significantly attenuated when 100 nmol Y-27632 was administered within three hours of the induction of ischemia. TUNEL assay and retrograde labeling of RGCs showed a decreased number of apoptotic cells and an increased number of RGCs in Y-27632-injected retinas. Moreover, silver nitrate staining and immunohistochemical analysis using an anti-LCA antibody showed that Y-27632 injection dramatically inhibited leukocyte infiltration and endothelial disarrangement.


CONCLUSIONS
Our data suggest that inhibition of Rho/ROCK signaling offers neuroprotective therapy against postischemic neural damage, by regulating leukocyte infiltration in the neural tissue.
Hirata
Akira
A
Department of Ophthalmology and Visual Science, Kumamoto University Graduate School of Medical Sciences, 1-1-1 Honjo, Kumamoto, 860-8556, Japan.
Inatani
Masaru
M
Inomata
Yasuya
Y
Yonemura
Naoko
N
Kawaji
Takahiro
T
Honjo
Megumi
M
Tanihara
Hidenobu
H
D000577:Amides / Q000627:therapeutic use*; D000818:Animals; D016923:Cell Death; D002470:Cell Survival / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007962:Leukocytes / Q000502:physiology; D008297:Male; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D011725:Pyridines / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000517:prevention & control*; D012164:Retinal Diseases / Q000517:prevention & control*; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000473:pathology; D012171:Retinal Vessels / Q000187:drug effects; D016622:Silver Staining; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*
D000577:Amides; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D011725:Pyridines; C108830:Y 27632; D054460:rho-Associated Kinases