Sano T, Umeda F, Hashimoto T, Nawata H, Utsumi H
Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Diabetologia. 1998 Nov;41(11):1355-60. doi: 10.1007/s001250051076.
Enhanced oxidative stress in diabetic patients may contribute to the pathogenesis of diabetic angiopathy. We have recently developed a method to determine the electron spin resonance (ESR, electron paramagnetic resonance; EPR) of reactive oxygen species and free radicals in vivo, using the nitroxide derivative, carbamoyl-PROXYL as a probe. In this study, diabetes was induced in Wistar rats by streptozotocin (STZ) injection (65 mg/kg, body weight, intravenously). Two, 4, and 8 weeks later, the animals received carbamoyl-PROXYL (300 nmol/g, intravenously), and ESR was measured at the upper abdominal level at a frequency of 300 MHz. The intensity of the carbamoyl-PROXYL ESR signal decreased gradually after the injection, and the spin clearance rate was determined over the first 5 min. At all time points, the spin clearance rate was significantly greater in the diabetic rats than in control rats. Moreover, the spin clearance rate in the diabetic rats was significantly correlated with urinary malondialdehyde (MDA) levels, which serve as a marker for lipid peroxidation. Daily treatment with 4 units neutral protamin Hagedorn (NPH) insulin for 4 weeks reduced the spin clearance rate in the diabetic rats. Simultaneous injection of carbamoyl-PROXYL and superoxide dismutase reduced the spin clearance rate in the diabetic rats in a dose-dependent manner. Injection of the antioxidant alpha-tocopherol (40 mg/kg, intraperitoneally) for 2 weeks restored the spin clearance rate in the diabetic rats without concomitant glycaemic restoration. These results suggest that a diabetic state enhances the generation of free radicals in vivo, and that both glycaemic control and antioxidant treatment can reduce this oxidative stress. Non-invasive in vivo ESR measurement may be useful for evaluating oxidative stress in diabetes.
糖尿病患者体内增强的氧化应激可能促成糖尿病性血管病的发病机制。我们最近研发了一种方法，以氨基甲酰 - PROXYL这种氮氧化物衍生物作为探针，来测定体内活性氧和自由基的电子自旋共振（ESR，电子顺磁共振；EPR）。在本研究中，通过静脉注射链脲佐菌素（STZ，65mg/kg体重）诱导Wistar大鼠患糖尿病。2周、4周和8周后，给动物静脉注射氨基甲酰 - PROXYL（300nmol/g），并在300MHz频率下测量上腹部水平的ESR。注射后氨基甲酰 - PROXYL的ESR信号强度逐渐降低，并在最初5分钟内测定自旋清除率。在所有时间点，糖尿病大鼠的自旋清除率均显著高于对照大鼠。此外，糖尿病大鼠的自旋清除率与作为脂质过氧化标志物的尿丙二醛（MDA）水平显著相关。每天用4单位中性鱼精蛋白锌胰岛素（NPH）治疗4周可降低糖尿病大鼠的自旋清除率。同时注射氨基甲酰 - PROXYL和超氧化物歧化酶可使糖尿病大鼠的自旋清除率呈剂量依赖性降低。腹腔注射抗氧化剂α - 生育酚（40mg/kg）2周可恢复糖尿病大鼠的自旋清除率，且血糖未随之恢复。这些结果表明，糖尿病状态会增强体内自由基的生成，血糖控制和抗氧化治疗均可减轻这种氧化应激。非侵入性体内ESR测量可能有助于评估糖尿病中的氧化应激。
