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目的:探讨不同浓度氯化镉染毒对大鼠肾脏功能的损伤及自噬在肾脏损伤中的作用,初步阐明镉损伤毒作用机制。方法:将40只大鼠随机分为空白对照组、低剂量染毒组(0.2mg·kg-1 CdCl2)、中剂量染毒组(0.4mg·kg-1 CdCl2)和高剂量染毒组(0.8mg·kg-1 CdCl2),每组10只。腹腔注射给予氯化镉溶液制备肾损伤模型,空白对照组大鼠给予等量生理盐水,观察大鼠一般状态和体质量。5周后,取大鼠肾脏组织和血液,检测肾功能相关指标肌酐、尿素氮和β2微球蛋白表达水平;原子吸收光谱法测定肾脏组织中镉水平;免疫组织化学法检测肾脏组织中自噬相关Beclin1蛋白的表达水平;Western blotting法检测肾脏组织中自噬相关蛋白LC3B的相对表达水平。结果:各染毒组大鼠明显精神萎靡,从染毒第3周开始,高剂量染毒组大鼠体质量增长减慢,显著低于空白对照组(P<0.05);至染毒结束,中、高剂量染毒组大鼠体质量均显著低于空白对照组(P<0.05)。中、高剂量染毒组大鼠血清肌肝、尿素氮和β2微球蛋白表达水平较空白对照组显著升高(P<0.05),且高剂量染毒组大鼠血清肌肝水平显著高于低剂量染毒组(P<0.05),中、高剂量染毒组大鼠尿素氮水平显著高于低剂量组(P<0.05)。原子吸收光谱法检测,各染毒组大鼠肾脏组织中蓄积大量金属镉,空白对照组仅见微量镉蓄积,且低、中和高剂量染毒组大鼠镉的蓄积量呈递增趋势。与低剂量染毒组比较,中、高剂量染毒组大鼠肾脏组织中镉水平显著升高(P<0.05);与中剂量染毒组比较,高剂量染毒组大鼠肾脏组织中镉水平显著升高(P<0.05)。免疫组织化学法检测,各染毒组大鼠肾脏组织中Beclin1蛋白表达水平显著高于空白对照组(P<0.05),且中、高剂量染毒组大鼠肾脏组织中Beclin1蛋白表达水平显著高于低剂量组(P<0.05),同时高剂量染毒组大鼠肾脏组织中Beclin1蛋白表达水平显著高于中剂量组(P<0.05)。Western blotting检测,各染毒组大鼠肾脏组织中LC3B蛋白相对表达水平显著高于空白对照组(P<0.05),且中、高剂量染毒组大鼠肾脏组织中LC3B蛋白相对表达水平显著高于低剂量组(P<0.05)。结论:在0.2~0.8mg·kg-1剂量范围内,随着氯化镉染毒剂量增加,镉对大鼠肾脏功能损伤逐渐加重,其机制可能与增加肾脏细胞自噬有关联。
OBJECTIVE: To investigate the effects of cadmium chloride exposure on renal function and autophagy in renal injury, and to elucidate the mechanism of cadmium toxicity. Methods: Forty rats were randomly divided into blank control group, low dose exposure group (0.2mg · kg-1 CdCl2), middle dose exposure group (0.4mg · kg-1 CdCl2) and high dose exposure group 0.8mg · kg-1 CdCl2), 10 in each group. Intraperitoneal injection of cadmium chloride solution to prepare the model of kidney injury, blank control group rats were given the same amount of normal saline, the general state of rats and body weight. After 5 weeks, the kidneys and blood of rats were taken out to measure the expression of creatinine, urea nitrogen and β2 microglobulin in renal function related indicators; cadmium levels in kidney were measured by atomic absorption spectrometry; autophagy Related Beclin1 protein expression; Western blotting method to detect the relative expression of autophagy-related protein LC3B in kidney tissue. RESULTS: The rats in each exposure group were obviously apathetic. The weight gain of rats in high-dose exposure group slowed down from the third week of exposure, which was significantly lower than that of the blank control group (P <0.05). At the end of exposure, The body weight of middle and high dose groups were significantly lower than that of blank control group (P <0.05). Compared with blank control group, the levels of serum liver fibrosis, blood urea nitrogen and β2 microglobulin in the medium and high dose groups were significantly increased (P <0.05), and the levels of serum muscle and liver in high dose group were significantly higher than those in the control group (P <0.05). The levels of urea nitrogen in the middle and high dose groups were significantly higher than those in the low dose group (P <0.05). Atomic absorption spectrometry showed that a large amount of metal cadmium was accumulated in the kidneys of rats in each exposure group, only a slight amount of cadmium was accumulated in the blank control group, and the accumulation of cadmium in the rats in the low, medium and high doses increased gradually. Compared with the low dose exposure group, the levels of cadmium in the kidney tissue of the middle and high dose exposure groups were significantly increased (P <0.05). Compared with the middle exposure exposure dose group, the levels of cadmium The level was significantly higher (P <0.05). Immunohistochemistry showed that the expression of Beclin1 protein in kidney tissue of rats in each exposure group was significantly higher than that in control group (P <0.05), and Beclin1 protein expression was significantly higher in middle and high dose groups In the low dose group (P <0.05), the expression of Beclin1 protein in the kidney tissue of the high dose exposure group was significantly higher than that of the middle dose group (P <0.05). Western blotting showed that the relative expression level of LC3B protein in kidney tissues of rats in each exposure group was significantly higher than that of the blank control group (P <0.05), and the relative expression level of LC3B protein in kidney tissues of medium and high dose exposure groups was significantly higher In low dose group (P <0.05). CONCLUSION: In the dose range of 0.2-0.8 mg · kg-1, cadmium has a gradual aggravating effect on renal function in rats with the cadmium chloride dose increasing, which may be related to increased autophagy in renal cells.