Tomita Masafumi, Okuyama Toshiko, Katsuyama Hironobu, Ishikawa Takaki
Department of Medical Toxicology, Kawasaki Medical School, Kurashiki 701-0192, Japan.
Arch Toxicol. 2006 Oct;80(10):687-93. doi: 10.1007/s00204-006-0092-2. Epub 2006 Mar 23.
Paraquat, one of the most widely used herbicides, is highly toxic to humans and animals. There is much information regarding its toxic effects on the lungs, but less is known about its toxicity in other organs. Paraquat is thought to play pivotal roles in the pathophysiology of acute renal failure and the progression of chronic kidney disease. We investigated the effects of paraquat on gene expression in the kidneys of rats treated with paraquat using a DNA array system, and the gene up-regulation observed was confirmed by quantitative real-time RT-PCR. Rats were sacrificed at 3, 24 h after the first injection (20 mg/kg), and at 3 h after the second injection. Expression of six genes had increased significantly by 3 h after the first injection: metallothionein-1 (MT-1), phosphoenolpyruvate carboxykinase, Na/K-transporting ATPase beta1 subunit, glutamate oxaloacetic transaminase, glutathione-S-transferase, and heme oxygenase-1 (HO-1). The transcription levels of MT-1 and HO-1 showed the biggest increases, but the increases did not continue until 24 h after injection, and the second injection had less effect than the first. Up-regulation of MT-1 and HO-1 mRNA levels was confirmed at the protein level. We observed a paraquat-induced increase of these proteins at 3 h post-injection, whereas this level did not continue until 24 h, as observed in RNA levels. The MT-1 protein in kidneys had been consumed. In addition, the protein level due to the second injection did not increase to the same level as that due to the first injection. These results suggest that protection against paraquat injury is mediated by induction of expression of some genes, and suppression on the induction of MT-1 and HO-1 may explain the injury observed due to paraquat intake. This is the first report of inducible pathways of defense against paraquat-induced oxidative stress in the kidney.
百草枯是使用最广泛的除草剂之一，对人类和动物具有高毒性。关于其对肺部的毒性作用已有很多信息，但对其在其他器官中的毒性了解较少。百草枯被认为在急性肾衰竭的病理生理学和慢性肾病的进展中起关键作用。我们使用DNA阵列系统研究了百草枯对用百草枯处理的大鼠肾脏中基因表达的影响，并且通过定量实时RT-PCR证实了观察到的基因上调。在首次注射（20mg/kg）后3小时、24小时以及第二次注射后3小时处死大鼠。首次注射后3小时，六个基因的表达显著增加：金属硫蛋白-1（MT-1）、磷酸烯醇丙酮酸羧激酶、钠/钾转运ATP酶β1亚基、谷氨酸草酰乙酸转氨酶、谷胱甘肽-S-转移酶和血红素加氧酶-1（HO-1）。MT-1和HO-1的转录水平增加最大，但这种增加在注射后24小时之前并未持续，并且第二次注射的影响小于第一次。在蛋白质水平证实了MT-1和HO-1 mRNA水平的上调。我们观察到注射后3小时这些蛋白质因百草枯诱导而增加，而正如在RNA水平观察到的那样，这种水平在24小时之前并未持续。肾脏中的MT-1蛋白已被消耗。此外，第二次注射后的蛋白质水平没有增加到与第一次注射相同的水平。这些结果表明，对百草枯损伤的保护是由一些基因表达的诱导介导的，并且对MT-1和HO-1诱导的抑制可能解释了因摄入百草枯而观察到的损伤。这是关于肾脏中针对百草枯诱导的氧化应激的诱导防御途径的首次报道。
