title: Early exposure of 17α-ethynylestradiol and diethylstilbestrol induces morphological changes and alters ovarian steroidogenic pathway enzyme gene expression in catfish, Clarias gariepinus.
abstract: Environmental estrogens are major cause of endocrine disruption in vertebrates, including aquatic organisms. Teleosts are valuable and popular models for studying the effects of endocrine disrupting chemicals (EDCs) in the environment. In the present study, we investigated the changes caused by exposure to the synthetic estrogens 17α-ethynylestradiol (EE2 ) and diethylstilbesterol (DES) during early stages of growth and sex differentiation of air-breathing catfish, Clarias gariepinus, at the morphological, histological, and molecular levels. Catfish hatchlings, 0 day post hatch (dph) were exposed continuously to sublethal doses of EE2 (50 ng/L) and DES (10 ng/L) until 50 dph and subsequently monitored for ovarian structural changes and alteration in the gene expression of steroidogenic enzymes till adulthood. Treated fish exhibited morphological deformities such as spinal curvature, stunted growth, and yolk-sac fluid retention. In addition to ovarian atrophy, DES-treated fish showed either rudimentary or malformed ovaries. Detailed histological studies revealed precocious oocyte development as well as follicular atresia. Further, transcript levels of various steroidogenic enzyme and transcription factor genes were altered in response to EE2 and DES. Activity of the rate-limiting enzyme of estrogen biosynthesis, aromatase, in the ovary as well as the brain of treated fish was in accordance with transcript level changes. These developmental and molecular effects imparted by EE2 and DES during early life stages of catfish could demonstrate the deleterious effects of estrogen exposure and provide reliable markers for estrogenic EDCs exposure in the environment.
authors.affiliation: Department of Animal Sciences, School of Life Sciences, University of Hyderabad, P O Central University, Hyderabad, 500 046, India.
authors.forename: P
authors.initials: P
authors.lastname: Sridevi
authors.forename: R K
authors.initials: RK
authors.lastname: Chaitanya
authors.forename: Y
authors.initials: Y
authors.lastname: Prathibha
authors.forename: S L
authors.initials: SL
authors.lastname: Balakrishna
authors.forename: A
authors.initials: A
authors.lastname: Dutta-Gupta
authors.forename: B
authors.initials: B
authors.lastname: Senthilkumaran
mesh_terms: D000818:Animals; D001141:Aromatase / Q000235:genetics; D002397:Catfishes / Q000378:metabolism; D004054:Diethylstilbestrol / Q000633:toxicity*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004967:Estrogens / Q000096:biosynthesis*; D004997:Ethinyl Estradiol / Q000633:toxicity*; D005260:Female; D015870:Gene Expression; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
chemical_list: D052244:Endocrine Disruptors; D004967:Estrogens; D004997:Ethinyl Estradiol; D004054:Diethylstilbestrol; D001141:Aromatase
keywords: 17α-ethynylestradiol; diethylstilbestrol; endocrine disruption; steroidogenesis; teleosts