Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
Comp Biochem Physiol C Toxicol Pharmacol. 2019 Aug;222:108-117. doi: 10.1016/j.cbpc.2019.04.016. Epub 2019 May 4.
Long-term exposure of triclosan (TCS), an important antimicrobial agent, can lead to deleterious effects on liver growth and development. However, the related mechanisms on TCS-induced hepatocyte injury remain unclear. Herein, we found that after long-time TCS exposure to adult zebrafish (Danio rerio) from 6 hpf (hours post-fertilization) to 90 dpf (days post-fertilization), the body weight and hepatic weight were significantly increased in concomitant with a large amount of lipid droplet accumulation in liver. Also, TCS exposure resulted in occurrence of oxidative stress by increasing the concentrations of malondialdehyde and reducing the activity of superoxide dismutase both in zebrafish larvae (120 hpf) and adult liver. By H&E staining, we observed a series of abnormal phenomena such as severely hepatocellular atrophy and necrosis, as well as prominently increased hepatic plate gap in TCS-exposure treatment groups. Through AO staining, TCS induced obvious apoptosis in larval heart and liver; through TUNEL assay, a concentration-dependent apoptosis was found to mainly occur in adult liver and its surrounding tissues. The mRNA and protein expression of anti-apoptotic protein Bcl-2 decreased, while that of pro-apoptosis protein Bax significantly increased, identifying that liver injury was closely related to hepatocyte apoptosis. The significant up-regulation of MAPK and p53 at both mRNA and protein levels proved that TCS-induced hepatocyte apoptosis was closely related to activating the MAPK/p53 signaling pathway. These results strongly suggest that long-term TCS-exposure may pose a great injury to zebrafish liver development by means of activating MAPK/p53 apoptotic signaling pathway, also lay theoretical foundation for further assessing TCS-induced ecological healthy risk.
长期暴露于三氯生（TCS）这种重要的抗菌剂可能会对肝脏的生长和发育产生有害影响。然而，TCS 诱导肝细胞损伤的相关机制仍不清楚。在此，我们发现，从 6 小时受精后（hpf）到 90 天受精后（dpf），成年斑马鱼（Danio rerio）长时间暴露于 TCS 后，体重和肝重显著增加，同时肝脏中大量脂质滴积累。此外，TCS 暴露通过增加丙二醛浓度和降低超氧化物歧化酶活性在斑马鱼幼虫（120 hpf）和成年肝脏中引起氧化应激。通过 H&E 染色，我们观察到一系列异常现象，如严重的肝细胞萎缩和坏死，以及 TCS 暴露处理组肝板间隙明显增大。通过 AO 染色，TCS 诱导幼虫心脏和肝脏明显凋亡；通过 TUNEL 测定，发现浓度依赖性凋亡主要发生在成年肝脏及其周围组织。抗凋亡蛋白 Bcl-2 的 mRNA 和蛋白表达降低，而促凋亡蛋白 Bax 的表达显著增加，表明肝损伤与肝细胞凋亡密切相关。MAPK 和 p53 的 mRNA 和蛋白水平的显著上调证明了 TCS 诱导的肝细胞凋亡与激活 MAPK/p53 信号通路密切相关。这些结果强烈表明，长期 TCS 暴露可能通过激活 MAPK/p53 凋亡信号通路对斑马鱼肝脏发育造成严重损害，也为进一步评估 TCS 诱导的生态健康风险奠定了理论基础。
