Retinal Oxygenation in Diabetic Retinopathy

糖尿病视网膜病变中的视网膜氧合

• 批准号: 6640274
• 负责人: BRUCE A. BERKOWITZ
• 金额: $ 25.9万
• 依托单位: WAYNE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6640274
• 关键词: carbon dioxide; diabetic retinopathy; early diagnosis; enzyme inhibitors; eye disorder diagnosis; fluosol; functional magnetic resonance imaging; genetically modified animals; histopathology; hyperglycemia; hypoxia; laboratory mouse; laboratory rat; nitric oxide synthase; oxygen tension; protein kinase C; retina

DESCRIPTION (provided by applicant): Current treatments for diabetic retinopathy are not entirely successful. We reason that therapies could be more rapidly developed and evaluated than is currently possible if a patient's risk of developing retinopathy could be predicted early in the course of the disease. We have developed a unique functional magnetic resonance imaging (fMRI) technique that measures the change in partial pressure of oxygen (deltaPO2) in the vitreous humor while the subject breathes carbogen (95% O2: 5% CO2). Using this acute retinal "stress" test, we have shown that carbogen breathing in rats and mice at 3-4 months of diabetes (before the appearance of retinal lesions) produces a significantly reduced retinal deltaPO2 compared to normals. A subnormal deltaPO2 is consistent with the presence of hypoxia but it cannot yet be unambiguously interpreted as a measure of hypoxia. In addition, in 3 month diabetic rats, aminoguanidine (AMG) treatment prevented the decrease in retinal deltaPO2. AMG is known to prevent retinal lesion formation in diabetic rats and inhibit the activity of both the inducible form of nitric oxide synthase (iNOS) and protein kinase C (PKC) (among other actions). Hypothesis: Subnormal retinal deltaPO2 in experimental diabetes is correlated with retinal hypoxia (Aim 1), and increased iNOS and PKC activity (Aims 2 and 3) but precedes the appearance of histopathology. Specific Aim 1) To compare retinal PO2 and deltaPO2 before, and at 2 wks, and 3 and 9 months of diabetes in rats. fMRI and a carbogen challenge will be used to measure the retinal deltaPO2. To measure PO2, a perfluorocarbon droplet will be injected into the preretinal vitreous over superior or inferior retina and 19F magnetic resonance spectroscopy performed. Specific Aim 2) To compare the retinal deltaPO2 (at 3 months) and histology (at 3 and 15 months) in normal and diabetic rats with and without treatment with a selective iNOS inhibitor (L-NIL (L-N(6)-(1-iminoethyl)lysine)), and in normal, diabetic, and diabetic iNOS knockout mice. Specific Aim 3) To compare the retinal deltaPO2 (at 3 months) and histology (at 3 and 15 months) in normal and diabetic rats with and without treatment with a selective PKC inhibitor (LY333531). In addition, we will compare retinal deltaPO2 in normal mice, transgenic mice that overexpress PKC beta II, diabetic mice, and diabetic PKC beta II-knockout mice. The results of the proposed studies will prove whether or not changes in retinal deltaPO2 correlate with the development of retinal hypoxia or multiple biochemical abnormalities that are associated with diabetic retinopathy but cannot be measured in vivo by existing techniques. The results of these studies could lead to the development of a non-invasive real time method for the early evaluation of diabetic retinopathy and its treatment.

描述（由申请人提供）：目前糖尿病视网膜病变的治疗并不完全成功。我们的理由是，如果可以在疾病早期预测患者发生视网膜病变的风险，治疗方法可以比目前更快地开发和评估。我们开发了一种独特的功能性磁共振成像（fMRI）技术，该技术可以测量受试者在呼吸Carbogen（95%O2：5%CO2）时玻璃体液中氧分压（deltaPO 2）的变化。使用这种急性视网膜“压力”测试，我们已经表明，在糖尿病3-4个月的大鼠和小鼠中（在视网膜病变出现之前），碳源呼吸与正常人相比产生了显着降低的视网膜deltaPO 2。低于正常的deltaPO 2与缺氧的存在是一致的，但它还不能被明确地解释为缺氧的测量。此外，在3个月的糖尿病大鼠中，氨基胍（AMG）治疗防止了视网膜δ PO 2的降低。已知AMG可预防糖尿病大鼠的视网膜病变形成，并抑制诱导型一氧化氮合酶（iNOS）和蛋白激酶C（PKC）的活性（以及其他作用）。假设：在实验性糖尿病中，低于正常的视网膜deltaPO 2与视网膜缺氧（目的1）、iNOS和PKC活性增加（目的2和3）相关，但先于组织病理学的出现。具体目的1）比较大鼠糖尿病前、2周、3个月和9个月时视网膜PO 2和deltaPO 2。将使用fMRI和carbogen激发来测量视网膜deltaPO 2。为了测量PO 2，将全氟化碳液滴注射到上级或低级视网膜上的视网膜前玻璃体中，并进行19 F磁共振波谱分析。具体目的2）比较正常和糖尿病大鼠（用和不用选择性iNOS抑制剂（L-NIL（L-N（6）-（1-亚氨基乙基）赖氨酸））治疗）以及正常、糖尿病和糖尿病iNOS敲除小鼠中的视网膜deltaPO 2（在3个月时）和组织学（在3个月和15个月时）。具体目的3）比较正常和糖尿病大鼠在用和不用选择性PKC抑制剂（LY 333531）治疗的情况下的视网膜deltaPO 2（在3个月时）和组织学（在3个月和15个月时）。此外，我们将比较正常小鼠、过度表达PKC β II的转基因小鼠、糖尿病小鼠和糖尿病PKC β II敲除小鼠的视网膜deltaPO 2。拟议研究的结果将证明视网膜deltaPO 2的变化是否与视网膜缺氧或与糖尿病视网膜病变相关但无法通过现有技术在体内测量的多种生化异常的发展相关。这些研究的结果可能会导致开发一种非侵入性的真实的时间方法来早期评估糖尿病视网膜病变及其治疗。