Inducible nitric oxide synthase mediates retinal DNA damage in Goto-Kakizaki rat retina.
OBJECTIVE
To examine the nitrosative and oxidative DNA damage induced by 8-nitroguanine and 8-hydroxy-2-deoxy guanosine (8-OHdG), and to determine the role played by inducible nitric oxide synthase (iNOS) in damage to DNA in the retina of the Goto-Kakizaki (GK) rat.


METHODS
Experiments were performed on GK rats, an animal model of spontaneous type 2 diabetes without obesity or visible diabetic vascular lesions. Immunohistochemistry was used to determine the retinal distribution of 8-nitroguanine, 8-OHdG, and iNOS in GK rats and control rats. The change in the expression of 8-nitroguanine and 8-OHdG in GK rats was also determined following an intravitreal injection of 1400W, an inhibitor of iNOS activity.


RESULTS
Immunohistochemical analysis showed that 8-nitroguanine and 8-OHdG were expressed strongly in the inner nuclear layer of GK retinas but only weakly in control retinas. This expression was correlated with an increase in the expression of iNOS in GK retinas, which was confirmed by the inhibition of iNOS activity by 1400W.


CONCLUSIONS
These findings demonstrate that iNOS plays a crucial role in nitrosative and oxidative DNA damage in GK rats, suggesting a retinal neurotoxic role of nitric oxide and superoxide in diabetic retinas.
Yuasa
Izumi
I
Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan. i-yama28@clin.medic.mie-u.ac.jp.
Ma
Ning
N
Department of Anatomy and Developmental Neurobiology, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima-Shi, Tokushima, Japan.
Matsubara
Hisashi
H
Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan.
Fukui
Yoshihiro
Y
Department of Anatomy and Developmental Neurobiology, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima-Shi, Tokushima, Japan.
Uji
Yukitaka
Y
Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan.
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D007097:Imines / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D008297:Male; D008856:Microscopy, Fluorescence; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000502:physiology*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012164:Retinal Diseases / Q000378:metabolism* / Q000473:pathology
C095838:8-nitroguanine; D004791:Enzyme Inhibitors; D007097:Imines; C496401:N-((3-(aminomethyl)phenyl)methyl)ethanimidamide; D006147:Guanine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D003849:Deoxyguanosine
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