阿霉素肾病大鼠中肾小球nephrin表达与氧化应激反应的关系

Relationship between glomerular nephrin expression and oxidative stress reaction in rats with adriamycin-induced nephrosis

摘要:

目的：氧化和抗氧化失衡可能是肾病综合征产生大量蛋白尿的原因之一，而肾小球裂隙膜分子nephrin在维持肾小球滤过屏障功能中起着重要作用。因此该实验初步探讨阿霉素肾病大鼠肾小球裂隙膜分子nephrin表达与氧化应激反应的关系，以及泼尼松和维生素E对阿霉素大鼠肾损伤保护作用的机制。方法：尾静脉单次注射阿霉素5 mg/kg建立肾病发病过程中的氧化应激模型，并增加泼尼松和维生素E干预。应用化学比色法检测肾皮质氧化应激指标变化，应用免疫组织化学技术观察肾小球裂隙膜分子nephrin表达变化，并对两者进行相关性分析。结果：①肾病组大鼠肾皮质丙二醛（MDA）含量及24 h尿蛋白排泄量高于正常对照组,超氧化物歧化酶（SOD）和总抗氧化能力（T-AOC）活性低于正常对照组。与肾病组相比，泼尼松和维生素E干预组从14 d开始尿蛋白排泄量明显减少，直到28 d（P<0.05）。维生素E干预组肾皮质MDA含量较肾病28 d组下降，SOD、T-AOC活性较肾病28 d组升高。②正常对照组大鼠nephrin沿肾小球基底膜呈深褐色连续线性分布；肾病组随时间的延长深褐色连续线性分布向浅褐色短线条状或点状分布转化；泼尼松和维生素E干预组减轻了nephrin分子的异常改变；量化分析显示,肾病组肾小球nephrin阳性表达含量明显低于正常对照组，泼尼松及维生素E干预组肾小球nephrin阳性表达含量较肾病组增加。③肾小球nephrin蛋白阳性表达含量与肾皮质MDA含量呈负相关，与肾皮质SOD和T-AOC活性呈正相关。结论：肾小球裂隙膜分子nephrin表达减少与氧化应激反应密切相关；泼尼松和维生素E对阿霉素肾病大鼠肾损伤有保护作用。［中国当代儿科杂志，2009，11（1）：56-60］

Abstract:

OBJECTIVE: It has been proposed that nephrotic syndrome is a consequence of an imbalance between oxidant and anti-oxidant activity. Nephrin plays an important role in maintaining glomerular filtration barrier. This study aimed to explore the relationship between the expression of glomerular nephrin and oxidative stress reaction in rats with adriamycin (ADR)-induced nephrosis, and the protection of prednisone and vitamin E against renal injuries. METHODS: Nephrosis was induced by single intravenous injection of ADR (5 mg/kg). The prednisone intervention group was administered with prednisone (10 mg/kg daily) between 1 and 4 weeks after ADR injection. The vitamin E intervention group received vitamin E of 20 mg/kg daily from 1 week before ADR injection till to 4 weeks after ADR injection. Control rats were intravenously injected with normal saline. After 7, 14, 21 and 28 days of ADR injection, the indexes of oxidative stress reaction of the renal cortex, malondialdehyde (MDA), superoxide dismutase (SOD) and total antioxidative capacity (T-AOC), were measured using the chemical chromatometry. The protein expression of glomerular nephrin was measured by immunohistochemistry. RESULTS: Prednisone or vitamin E treatment reduced urinary protein from 14 days to 28 days after ADR injection. MDA levels of renal cortex increased, while renal activities of SOD and T-AOC as well as nephrin protein contents decreased in untreated nephrosis group from 7 days after ADR injection compared with those in the control rats. Compared with the untreated nephrosis group, prednisone treatment resulted in an increase in nephrin protein contents 28 days after ADR injection; Vitamin E treatment decreased renal MDA levels and increased renal activities of SOD and T-AOC and nephrin protein contents 28 days after ADR injection. Nephrin staining showed a sable linear-like pattern along the capillary loops of glomerulus in the control rats. Nephrin staining presented a light tan discontinuous short linear-like or punctiform pattern along the capillary loops of glomerulus in the untreated ADR group. Prednisone or vitamin E treatment ameliorated abnormal expression of nephrin induced by nephrosis. Glomerular nephrin expression level was negatively correlated with renal MDA level and positively correlated with renal activities of SOD and T-AOC. CONCLUSIONS: A reduction of glomerular nephrin expression is closely related to oxidative stress reaction. Prednisone and vitamin E have protective effects against renal injuries induced by ADR in rats.［Chin J Contemp Pediatr, 2009, 11 (1):56-60］