title: Impairment of the cortisol stress response mediated by the hypothalamus-pituitary-interrenal (HPI) axis in zebrafish (Danio rerio) exposed to monocrotophos pesticide.
abstract: In teleosts, an important component of the stress response is coordinated by the hypothalamic-pituitary-interrenal (HPI) axis. Environmental contaminants might disrupt the stress axis and consequently affect the stress response in fish. To investigate the effect of monocrotophos (MCP) pesticide on the stress response of fish and its potential mechanisms, adult zebrafish (Danio rerio) were exposed to 0, 1, 10, and 100μg/L of a 40% MCP-based pesticide for 21d, after which time fish were subjected to a 3-min air-exposure stressor. Concentrations of the whole-body cortisol were measured by radioimmunoassay and abundances of transcripts of proteins involved in the HPI axis were determined using quantitative real-time PCR. Results showed that 100μg/L of MCP pesticide decreased whole-body cortisol levels of female zebrafish in response to an acute stressor, but without any effect on the cortisol response in males. 100μg/L MCP pesticide reduced POMC and GR expression in the brain, MC2R and P45011β expression in the head kidney, but enhanced 20β-HSD2 expression in the head kidney, suggesting that MCP damaged the HPI axis involving acting at pituitary regulatory levels, inhibiting cortisol synthesis and stimulating cortisol catabolism, or disturbing the negative feedback regulation. Additionally, MCP depressed liver GR transcription but did not affect phosphoenolpyruvate carboxykinase and tyrosine aminotransferase expression in zebrafish, suggesting a role for this pesticide in reducing target tissue responsiveness to cortisol. Considered together, the reduced ability to elevate cortisol levels in response to an acute stress may be an endocrine dysfunction occurring in zebrafish subchronically exposed to MCP pesticide.
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
authors.forename: Xiaona
authors.initials: X
authors.lastname: Zhang
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Tian
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China. Electronic address: rusg@ouc.edu.cn.
authors.forename: Shaoguo
authors.initials: S
authors.lastname: Ru
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D052244:Endocrine Disruptors / Q000633:toxicity*; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006854:Hydrocortisone / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D007306:Insecticides / Q000633:toxicity*; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008999:Monocrotophos / Q000633:toxicity*; D012333:RNA, Messenger / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects*; D013997:Time Factors; D014158:Transcription, Genetic; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D052244:Endocrine Disruptors; D029941:Fish Proteins; D007306:Insecticides; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D008999:Monocrotophos; D006854:Hydrocortisone
keywords: Cortisol; Hypothalamus–pituitary–interrenal axis; Monocrotophos pesticide; Stress response; Zebrafish