Yuasa Izumi, Ma Ning, Matsubara Hisashi, Fukui Yoshihiro, Uji Yukitaka
Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan.
Department of Anatomy and Developmental Neurobiology, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima-Shi, Tokushima, Japan.
Jpn J Ophthalmol. 2008 Jul-Aug;52(4):314-322. doi: 10.1007/s10384-008-0542-x. Epub 2008 Sep 5.
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.
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.
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.
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.
研究8-硝基鸟嘌呤和8-羟基-2'-脱氧鸟苷（8-OHdG）诱导的亚硝化和氧化DNA损伤，并确定诱导型一氧化氮合酶（iNOS）在Goto-Kakizaki（GK）大鼠视网膜DNA损伤中所起的作用。
对GK大鼠进行实验，GK大鼠是一种无肥胖或明显糖尿病血管病变的自发性2型糖尿病动物模型。采用免疫组织化学方法确定GK大鼠和对照大鼠视网膜中8-硝基鸟嘌呤、8-OHdG和iNOS的分布。在玻璃体内注射iNOS活性抑制剂1400W后，还测定了GK大鼠中8-硝基鸟嘌呤和8-OHdG表达的变化。
免疫组织化学分析显示，8-硝基鸟嘌呤和8-OHdG在GK大鼠视网膜内核层中强烈表达，而在对照视网膜中仅微弱表达。这种表达与GK大鼠视网膜中iNOS表达的增加相关，1400W对iNOS活性的抑制证实了这一点。
这些发现表明，iNOS在GK大鼠的亚硝化和氧化DNA损伤中起关键作用，提示一氧化氮和超氧化物在糖尿病视网膜中具有视网膜神经毒性作用。
