title: Long-term exposure to triphenylphosphate alters hormone balance and HPG, HPI, and HPT gene expression in zebrafish (Danio rerio).
abstract: With the global decline in the use of polybrominated diphenyl ethers, the demand for alternative flame retardants, such as triphenylphosphate (TPP), has increased substantially. Triphenylphosphate is now detected in various environments including aquatic ecosystems worldwide. However, studies on the toxicological consequences of chronic TPP exposure on aquatic organisms are scarce. The zebrafish model was used to investigate the effects of long-term TPP exposure on the endocrine system. Zebrafish embryos were exposed to 5 µg/L, 50 µg/L, or 500 µg/L TPP for 120 d, and hormonal and transcriptional responses were measured along the hypothalamic-pituitary-gonad (HPG) axis, the hypothalamic-pituitary-interrenal (HPI) axis, and the hypothalamic-pituitary-thyroid (HPT) axis. Exposure to TPP significantly increased plasma 17β-estradiol, but decreased 11-ketotestosterone in both sexes. Gene expression data support these changes. In the HPI axis, plasma cortisol and proopiomelanocortin (pomc) and mineralocorticoid receptor transcripts increased in females, but in males cortisol decreased whereas pomc increased (p < 0.05). Thyroxine and triiodothyronine increased, and thyrotrophin-releasing hormone receptor 2 (trhr2) and trh expression were affected only in females (p < 0.05). In summary, long-term exposure to TPP enhanced estrogenicity in both males and females, potentially through influencing the HPG axis, but modulated the HPI, and HPT axes differently by sex, suggesting that both genomic and nongenomic responses might be involved. Environ Toxicol Chem 2016;35:2288-2296. © 2016 SETAC.
authors: School of Public Health, Seoul National University, Seoul, Republic of Korea.|School of Public Health, Guangdong Medical University, Dongguan City, Guangdong Province, People's Republic of China.
authors: Xiaoshan
authors: X
authors: Liu
authors: School of Public Health, Seoul National University, Seoul, Republic of Korea.|Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea.
authors: Dawoon
authors: D
authors: Jung
authors: School of Public Health, Seoul National University, Seoul, Republic of Korea.|National Institute of Environmental Research, Incheon, Republic of Korea.
authors: Areum
authors: A
authors: Jo
authors: Department of Occupational and Environmental Health, Yongin University, Yongin, Republic of Korea.
authors: Kyunghee
authors: K
authors: Ji
authors: Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan, Republic of Korea.
authors: Hyo-Bang
authors: HB
authors: Moon
authors: School of Public Health, Seoul National University, Seoul, Republic of Korea.|Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea.
authors: Kyungho
authors: K
authors: Choi
mesh_terms: D000818:Animals; D004703:Endocrine System / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000097:blood / Q000235:genetics; D005260:Female; D005411:Flame Retardants / Q000633:toxicity*; D015870:Gene Expression / Q000187:drug effects*; D008297:Male; D010755:Organophosphates / Q000633:toxicity*; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood / Q000235:genetics; D013963:Thyroid Hormones / Q000097:blood / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000097:blood / Q000378:metabolism*
chemical_list: D005411:Flame Retardants; D010755:Organophosphates; D013963:Thyroid Hormones; D014874:Water Pollutants, Chemical; D013739:Testosterone; D004958:Estradiol; C003600:11-ketotestosterone; C005445:triphenyl phosphate
keywords: Endocrine disruptors; Flame retardants; Organophosphates; Sex hormone; Thyroid hormone