Belforte Nicolás, Moreno María Cecilia, Cymeryng Cora, Bordone Melina, Keller Sarmiento María Inés, Rosenstein Ruth E
Laboratorio de Neuroquímica Retiniana y Oftalmología Experimental, Universidad de Buenos Aires, Centro de Estudios Farmacológicos y Botánicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
Invest Ophthalmol Vis Sci. 2007 May;48(5):2127-33. doi: 10.1167/iovs.06-1229.
Understanding the mechanisms of neuronal cell death in glaucoma is important for devising new treatments. Excitatory amino acids, excessive Ca(2+) influx, and formation of nitric oxide (NO) via NO synthase (NOS)-1 could be involved in glaucomatous neuropathy. The purpose of the present study was to examine the retinal nitridergic pathway activity in rats exposed to experimentally elevated intraocular pressure.
Weekly injections of HA were performed unilaterally in the rat anterior chamber, whereas the contralateral eye was injected with saline solution. At 3 or 6 weeks of treatment, retinal NOS activity was assessed through the conversion of (3)H-L-arginine to (3)H-L-citrulline, whereas NOS-1, -2, and -3 levels were assessed by Western blotting. L-Arginine uptake was measured using (3)H-l-arginine, whereas mRNA levels of L-arginine transporters were determined by semiquantitative RT-PCR. In addition, cyclic guanosine monophosphate (cGMP) levels were quantified by radioimmunoassay.
At both 3 and 6 weeks of treatment, NOS activity significantly increased in HA-injected eyes although no changes in retinal NOS-1, -2, or -3 levels were observed in eyes injected with HA. L-Arginine influx and mRNA levels of cationic amino acid transporter type (CAT)-1 and -2 significantly increased in retinas from hypertensive eyes. Retinal cGMP levels significantly increased in eyes injected with HA for 3 but not 6 weeks.
These results suggest a significant activation of the retinal nitridergic pathway in hypertensive eyes.
了解青光眼患者神经元细胞死亡的机制对于设计新的治疗方法至关重要。兴奋性氨基酸、过量的Ca(2+)内流以及通过一氧化氮合酶（NOS）-1生成一氧化氮（NO）可能与青光眼性神经病变有关。本研究的目的是检测实验性眼压升高的大鼠视网膜氮能通路活性。
每周一次向大鼠前房单侧注射透明质酸（HA），而对侧眼注射盐溶液。在治疗3周或6周时，通过将(3)H-L-精氨酸转化为(3)H-L-瓜氨酸来评估视网膜NOS活性，而通过蛋白质印迹法评估NOS-1、-2和-3的水平。使用(3)H-L-精氨酸测量L-精氨酸摄取，而通过半定量逆转录聚合酶链反应（RT-PCR）测定L-精氨酸转运体的mRNA水平。此外，通过放射免疫测定法定量环磷酸鸟苷（cGMP）水平。
在治疗3周和6周时，注射HA的眼睛中NOS活性均显著增加，尽管注射HA的眼睛中视网膜NOS-1、-2或-3水平未观察到变化。高血压眼视网膜中L-精氨酸内流以及阳离子氨基酸转运体（CAT）-1和-2的mRNA水平显著增加。注射HA 3周而非6周的眼睛中视网膜cGMP水平显著增加。
这些结果表明高血压眼中视网膜氮能通路有显著激活。
