Terelak-Borys Barbara, Czechowicz-Janicka Krystyna
Ophthalmology Department, Medical Centre of Postgraduate Education, Warsaw, Poland.
Klin Oczna. 2011;113(7-9):201-8.
Spasm of blood vessels supplying the optic nerve head is considered one of possible ischaemic mechanisms of glaucomatous optic neuropathy.
The aim of the study was to evaluate the role of two potent and long-acting vasoconstrictors: endothelin-1 (ET-1) and neuropetide Y (NPY) in the pathogenesis of glaucoma by: 1) measurement of plasma ET-1 and NPY concentrations in primary open-angle glaucoma (POAG) patients with high intraocular pressure (HTG patients) and with normal intraocular pressure (NTG patients) at baseline and following peripheral exposure to cold (cold-pressor test), 2) assessment whether changes, if any, in the plasma concentrations of both peptides following the cold-pressor test correlate with visual field defects.
The study was conducted in three groups of subjects: 1) HTG patients, 2) NTG patients and 3) controls. All subjects were young and free from any cardiovascular disorders. ET-1 and NPY concentrations in the plasma were measured by radioimmunoassay (ET-1: Amersham International UK, NPY: Peninsula Laboratories INC). The cold-pressor test was performed by immersing the whole hand in ice-cold water (4 degrees C) for 2 minutes. Visual fields were examined using standard automated perimetry (Octopus 101, G-2 programme, normal strategy).
In the NTG patients the mean baseline plasma ET-1 concentration was significantly lower and the mean baseline plasma NPY concentration significantly higher compared to controls. On the other hand, there were no statistically significant differences in the mean baseline peptide levels between the HTG patients and the control subjects. After the cold-pressor test the mean ET-1 concentrations considerably increased in the three groups. The highest increase was seen in the NTG group and it was statistically significant compared to the HTG group and controls. Following the cold-pressor test the mean NPY concentration was significantly decreased in the NTG group, but remained virtually unchanged in the HTG group and controls. In the NTG patients, significant increase in the mean ET-1 concentration and decrease in the mean NPY concentration seen after the cold-pressor test were accompanied by a significant decrease in the mean MS (mean retinal sensitivity) value in the second eye examined after the cold-pressor test, but no correlation was found between changes in the MS values and changes in the ET-1 and NPY concentrations. There were no significant changes in the mean MS values after cold-pressor test in the HTG patients and controls.
Our findings suggest abnormal neuro-endothelial mechanisms of vascular tone control in NTG patients, related to the effects of ET-1 and NPY, secondary to endothelial dysfunction and to dysregulation of the autonomic nervous system. These abnormalities may involve potentiation of the vasoconstrictive effects of both ET-1 and NPY leading to the optic nerve head ischaemia and subsequent development of visual field defects in the course of normal-tension glaucoma.
供应视神经乳头的血管痉挛被认为是青光眼性视神经病变可能的缺血机制之一。
本研究旨在通过以下方式评估两种强效长效血管收缩剂：内皮素 -1（ET -1）和神经肽 Y（NPY）在青光眼发病机制中的作用：1）测量原发性开角型青光眼（POAG）高眼压患者（HTG 患者）和眼压正常患者（NTG 患者）在基线时以及外周暴露于寒冷环境（冷加压试验）后的血浆 ET -1 和 NPY 浓度，2）评估冷加压试验后两种肽的血浆浓度变化（若有）是否与视野缺损相关。
研究在三组受试者中进行：1）HTG 患者，2）NTG 患者和 3）对照组。所有受试者均年轻且无任何心血管疾病。采用放射免疫分析法（ET -1：英国阿美士德国际公司，NPY：半岛实验室公司）测量血浆中的 ET -1 和 NPY 浓度。冷加压试验通过将整只手浸入冰冷水中（4 摄氏度）2 分钟来进行。使用标准自动视野计（Octopus 101，G -2 程序，正常策略）检查视野。
与对照组相比，NTG 患者的平均基线血浆 ET -1 浓度显著更低，平均基线血浆 NPY 浓度显著更高。另一方面，HTG 患者与对照受试者之间的平均基线肽水平无统计学显著差异。冷加压试验后，三组的平均 ET -1 浓度均显著升高。NTG 组升高幅度最大，与 HTG 组和对照组相比具有统计学显著性。冷加压试验后，NTG 组的平均 NPY 浓度显著降低，但 HTG 组和对照组基本保持不变。在 NTG 患者中，冷加压试验后平均 ET -1 浓度显著升高和平均 NPY 浓度降低，同时冷加压试验后检查的第二只眼中平均 MS（平均视网膜敏感度）值显著降低，但未发现 MS 值变化与 ET -1 和 NPY 浓度变化之间存在相关性。HTG 患者和对照组冷加压试验后平均 MS 值无显著变化。
我们的研究结果表明，NTG 患者存在与 ET -１和 NPY 作用相关的异常神经 - 内皮血管张力控制机制，继发于内皮功能障碍和自主神经系统失调。这些异常可能涉及增强 ET -1 和 NPY 的血管收缩作用，导致视神经乳头缺血以及正常眼压性青光眼病程中视野缺损的后续发展。
