title: A rapid in vivo zebrafish model to elucidate oxidative stress-mediated PCB126-induced apoptosis and developmental toxicity.
abstract: Dioxin-like 3,3',4,4',5-pentachlorobiphenyl (PCB126) is one of the most potent and widespread environmental pollutants. Although PCB126-induced toxicity is related to the aryl hydrocarbon receptor pathway, there is still no study that has constructed an in vivo visual model to clarify the role of the Nrf2/ARE signaling pathway in the oxidative stress mechanism of PCB126-induced toxicity. In the present study, an in vivo zebrafish model of nrf2a fused to enhanced green fluorescent protein (nrf2a-eGFP) was constructed. The zebrafish embryos microinjected with nrf2a-eGFP (72h postfertilization) were exposed to various concentrations of PCB126 (0, 25, 50, 100, 200μg/L) or 30mMN-acetylcysteine (NAC)+200μg/L PCB126. After 72h exposure, PCB126 significantly increased the malformation rates and induced eGFP expression in a dose-dependent manner in several zebrafish tissue types. The distribution of eGFP fluorescence coincided with developmental deformity sites. NAC pretreatment effectively counteracted PCB126-induced developmental toxicity including heart rate, pericardial edema, and body length. The highest PCB126 dose, 200μg/L, produced marked apoptosis in the eye, gill, and trunk detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. At 48 and 72h exposure, 200μg/L PCB126 affected glutathione metabolism as evidenced by decreased glutathione and increased glutathione disulfide concentrations, indicative of oxidative stress. These effects were also counteracted by NAC pretreatment. Furthermore, the Nrf2-regulated genes gclc, gpx, gstp1, and hmox1 were significantly induced at 24, 48, and 72h at the highest PCB126 exposures but not in the NAC-pretreated group. In addition, a significant increase in ROS generation was detected in zebrafish larvae at 72h PCB126 exposure, which might offer a link for future mechanistic studies. Collectively, these data suggest that PCB126-induced developmental toxicity and apoptosis in the nrf2a-eGFP-injected zebrafish model are due to oxidative stress mediated by disruption to glutathione metabolism and changes in Nrf2-regulated gene expression.
authors.affiliation: College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, People׳s Republic of China.
authors.forename: Han
authors.initials: H
authors.lastname: Liu
authors.affiliation: Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln 7647, New Zealand.
authors.forename: Ravi
authors.initials: R
authors.lastname: Gooneratne
authors.affiliation: College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, People׳s Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.affiliation: College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, People׳s Republic of China.
authors.forename: Ruifang
authors.initials: R
authors.lastname: Lai
authors.affiliation: College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, People׳s Republic of China.
authors.forename: Jin
authors.initials: J
authors.lastname: Wei
authors.affiliation: College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, People׳s Republic of China. Electronic address: wangwm@mail.hzau.edu.cn.
authors.forename: Weimin
authors.initials: W
authors.lastname: Wang
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D003553:Cystine / Q000031:analogs & derivatives / Q000494:pharmacology; D004785:Environmental Pollutants / Q000633:toxicity*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D017930:Genes, Reporter; D005978:Glutathione / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D051267:NF-E2-Related Factor 2 / Q000096:biosynthesis / Q000235:genetics; D018384:Oxidative Stress; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D011401:Promoter Regions, Genetic; D017382:Reactive Oxygen Species / Q000378:metabolism; D017422:Sequence Analysis, DNA; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000975:Antioxidants; D004785:Environmental Pollutants; D051267:NF-E2-Related Factor 2; D017382:Reactive Oxygen Species; D029961:Zebrafish Proteins; C485184:enhanced green fluorescent protein; C495638:nfe2l2a protein, zebrafish; D049452:Green Fluorescent Proteins; D003553:Cystine; D011078:Polychlorinated Biphenyls; D005978:Glutathione; C023035:3,4,5,3',4'-pentachlorobiphenyl; C030905:N-monoacetylcystine
keywords: Apoptosis; Developmental toxicity; Free radicals; Glutathione metabolism; Nrf2a; PCB126; Zebrafish