环境镍暴露对大鼠代谢损伤的生态毒理学研究

Nickel exposure through the water, air and soil pollution has become a serious threat to the ecological environment and human health, because of its interference effect on the body's endocrine metabolic state, it had been considered as one of the Environmental Endocrine Disruptors. Endocrine glands, especially the thyroid and pancreas, are the core organs of energy metabolism regulation, they balance the metabolism of carbohydrate, fat and protein through strict feedback mechanism. The study of metabolic regulation and the lesions of pancreas and thyroid is an intersection of the ecological destruction and the body injury caused by nickel pollution. Our study plans to take Wistar rats as subjects, using chemiluminescence technology, morphological analysis and immunohistochemical methods to detect the glucolipid metabolic changes, thyroid function, islet function state, and histomorphology changes of rats exposed to nickel environment, and discuss the effects of environmental nickel exposure on energy metabolism and the related organs. At the same time, we will detect the apoptotic cells, and the expression of Caspase-3, Bax/Bcl-2 and Fas/FasL on both mRNA level and protein level, using RT-PCR, immunohistochemical method and flow cytometry, to explore the possible mechanism of metabolic damage caused by environmental nickel exposure, and provide scientific evidence for relevant protection work in the future.

镍暴露通过对水、空气、土壤的污染日渐成为威胁生态环境和人类健康的热点，由于其对机体内分泌代谢状态的干扰效应，已被列入内分泌环境干扰物之一。内分泌腺体特别是甲状腺和胰腺通过严密反馈机制调控着机体三大物质的代谢平衡，是能量代谢的核心调控器官。镍与机体代谢调控及胰腺、甲状腺损伤间的研究属于镍污染对生态破坏与机体损伤的一个交叉点。本课题拟以Wistar 大鼠为受试对象，采用化学发光技术、组织形态学分析等方法，检测镍暴露环境下大鼠糖脂代谢变化、甲状腺功能与胰岛功能状态、组织形态学变化，探讨镍暴露环境对机体能量代谢与相关调控腺体的损伤程度；并同步采用免疫组化、RT-PCR、流式细胞术检测这两种腺体中Caspase-3、Bax/Bcl-2、Fas/FasL在mRNA和蛋白水平的表达及凋亡细胞，进一步探讨环境镍暴露代谢损伤的可能机制，为今后相关防护工作的开展提供科学依据。

镍作为环境内分泌干扰物对甲状腺及胰腺的影响是肯定的。甲状腺及胰腺是参与机体三大物质能量代谢调节的核心器官，但目前镍对它们的研究相对较少，且机制尚不清楚。本课题采用硫酸镍（NiSO4）制备大鼠镍暴露模型，检测其肝肾功、甲功、胰岛功能及病理形态学改变，并进行大鼠肝肾组织氧化应激指标及mRNA及蛋白水平凋亡相关指标的检测，探讨镍暴露对大鼠脂质过氧化作用及对甲状腺及胰腺组织的损伤发生发展的可能凋亡机制。又采用镍染毒人甲状腺滤泡上皮细胞及胰腺导管上皮细胞模型，进一步明确镍对上述细胞损伤的剂量及时间效应关系及与线粒体凋亡通路间的相关性。结果示1.NiSO4可导致大鼠肾功、甲状腺功能和胰岛功能异常；2.NiSO4染毒大鼠后，高剂量组大鼠甲状腺及胰腺组织病理出现明显改变；3.大鼠肝肾组织氧化应激指标变化：镍暴露可升高大鼠肾组织MDA水平；大鼠肝、肾组织SOD活力呈先上升后下降趋势，而低、中剂量组肝肾组织中Nrf2及HO-1 mRNA表达水平均显著上升。因此亚慢性NiSO4染毒对大鼠肝脏、肾脏影响的机制可能与氧化应激、激活Nrf2抗氧化信号通路密切相关；4.甲状腺及胰腺凋亡相关指标检测：NiSO4染毒后，大鼠甲状腺及胰腺组织Caspase-8、Caspase-9、Caspase-3 、Fas mRNA表达水平较对照组升高，高剂量NiSO4染毒组 Bcl-2的mRNA表达水平降低。且甲状腺及胰腺 Caspase-3、Fas和Bax蛋白表达水平与 mRNA 表达一致。说明NiSO4可能通过介导Caspase依赖线粒体凋亡途径和Fas信号通路诱导大鼠甲状腺组织及胰腺组织发生细胞凋亡。5.NiSO4对人甲状腺滤泡上皮细胞及胰腺导管上皮细胞活力有影响，并可能通过降低人Nthy细胞及HPNE细胞的线粒体膜电位水平致使细胞发生凋亡，且凋亡作用的产生呈现剂量依赖性，从而影响人Nthy细胞及HPNE细胞能量代谢。