一氧化氮在早产儿视网膜病变中的作用

Effect of nitric oxide on retinopathy of prematurity

目的研究一氧化氮(NO)在早产儿视网膜病变(ROP)中的作用及其与血管内皮生长因子(VEGF)的相互关系。方法建立高浓度氧诱导的SD新生鼠ROP模型,腹腔分别注射结构型一氧化氮合酶(cNOS)抑制剂L-NNA150mg/(kg·d)和诱导型NOS(iNOS)抑制剂L-NIL25mg/(kg·d)。一段时间后,取新生鼠眼球制备切片计数视网膜新生血管内皮细胞数,Westernblot法检测VEGF。结果氧气组视网膜cNOS活力较空气组显著增高(P<0.05),iNOS活力明显降低(P<0.05)。L-NNA治疗组与对照组比较,视网膜新生血管内皮细胞数显著减少(P<0.05),VEGF在高氧期表达增加60.38%,相对低氧期表达减少17.97%,以上指标L-NIL治疗组与对照组差异均无统计学意义(P>0.05)。结论抑制cNOS产生的NO能减少后者引起的血管活性以及细胞毒性效应,从而减轻对血管内皮细胞的损伤,并且能下调视网膜VEGF的表达。

Objective Nitric oxide（NO） is a signaling molecule with multiple effects. It is associated with many diseases in ophthalmology. Present paper was to study the effect of NO on retinopathy of prematurity（ROP） and its relation with vascular endothelial growth factor（VEGF）. Methods The ROP model of 184 newborn Sprague-Dawley （SD） rats was induced by hyperxia. The rats in oxygen group were bred under the oxygen concentration of （80 ± 2） % for 21 hours and then in air for 3 hours per day until 11 days and sequentially in air for 7 days, and rats in normoxia group were bred in air for 18 days. Constructive NO syntheses （cNOS） inhibitor L-NNA （ 150 mg/kg · d） or induced NO syntheses （iNOS） inhibitor L-NIL （25 mg/kg · d） were intraperitoneally injected to the rats. Eyeballs of newborn rats were enucleated in the 19th day following modeling for hematoxylin and eosin staining to count the nuclei of proliferative retinal vessels. Retina of rats was isolated to determine the absorbance of activity of NOS and the expression of VEGF by Western blot. Results The activity of cNOS in retina of ROP models of SD newborns （0. 195 3 ± 0. 024 4 U/mgprot in hyperxia period and 0. 147 2 ± 0. 014 9 U/mgprot in relative hypoxia period） was significantly increased in comparison with normoxia group（0. 123 7 ± 0. 038 0 U/mgprot in hyperxia period and 0. 095 9 ± 0. 026 8 U/mgprot in relative hypoxia period） （ P 〈 0. 05 ） , but that of iNOS was significantly decreased （ P 〈 0. 05 ）. Compared with control group （135.18 ± 22.99 in hyperxia period and 135.15 ± 23.36 in relative hypoxia period） , the number of nuclei of proliferative retinal vessels in L-NNA treated group（ 89.19 ± 11.86 in hyperxia period and 79.62 ±10.87 in relative hypoxia period） was significantly decreased （P 〈 0. 05） and the expression of VEGF in retina increased by 60.38% in hyperxia period but decreased by 17.97% in relative hypoxia period. There was no significant difference in above indexes between L-NIL treated group and control group （ P 〉 0. 05 ）. Conclusion Inhibition of cNOS depresses retinal neovascularization by reducing NO induced activity of vascular and cytotoxicity,decreasing the impairment of vascular endothelial cell and downloading the expression of VEGF in retina.