A review of studies on androgen and estrogen exposure in fish early life stages: effects on gene and hormonal control of sexual differentiation

• Published in: Journal of applied toxicology Vol. 31; no. 5; pp. 379 - 398
• Main Authors: Leet, Jessica K., Gall, Heather E., Sepúlveda, Maria S.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-07-2011; Wiley; Wiley Subscription Services, Inc
• Subjects: Agnatha. Pisces; Androgens - toxicity; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; cyp19; Differentiation; dmrt1; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Embryo, Nonmammalian - drug effects; Embryos; endocrine disrupting chemicals; Environmental Monitoring; Environmental pollutants toxicology; Estrogens; Estrogens - toxicity; Female; Fish; Fishes - physiology; foxl2; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression Profiling; Gene Expression Regulation, Developmental - drug effects; Genes; Hormones; Larva - drug effects; Larvae; Male; Medical sciences; Sex; sex determination; Sex Determination Processes - drug effects; Sex Determination Processes - genetics; sex differentiation; Sex Differentiation - drug effects; Sex Differentiation - genetics; sox9; teleosts; Toxicology; Water; Water Pollutants, Chemical - toxicity; foxl2; endocrine disrupting chemicals; hormones; Chemical compound; Estrogen; Sex; Early stage; cyp19; Review; Gene; Sex determination; Pisces; Genetics; Fish; Sexual differentiation; teleosts; Androgen; Animal origin; sox9; Exposure; Endocrine disruptor; Cell differentiation; Gene expression; Ovarian hormone; sex differentiation; Vertebrata; dmrt1; Water pollution; Sex steroid hormone; Bibliographic review
• ISSN: 0260-437X; 1099-1263; 1099-1263
• DOI: 10.1002/jat.1682

ABSTRACT
Teleost fish are unique among vertebrates in that phenotypic sex or onset of sex inversion can be easily manipulated by hormonal treatments. In recent years, researchers have begun reporting concentrations of synthetic and natural hormones in the environment. Although concentrations are very low (in the parts per trillion to low parts per billion), they are still of concern because of the high potency of synthetic hormones and the enhanced susceptibility of teleost fishes, especially early life stages, to hormonal exposures. In this review, we will focus on sex differentiation in teleost fishes and how these processes in fish early life stages may be impacted by environmental hormones which are known to contaminate aquatic environments. We will start by reviewing information on sources and concentrations of hormones in the environment and continue by summarizing the state of knowledge of sex differentiation in teleost gonochoristic fishes, including information on genes involved (e.g. cyp19, dmrt1, sox9 and foxl2). We will end our review with a summary of studies that have examined the effects of androgens and estrogens on fish sex differentiation after exposure of fish embryos and larvae and with ideas for future research. Copyright © 2011 John Wiley & Sons, Ltd.
Even at low concentrations hormones in the environment are of concern for teleost fishes, especially at early life stages. This review is a brief overview of the sources of steroid hormones in the environment, sex differentiation in fish and publications on early life stage fish exposed to various hormones found in the environment. The publications reviewed mainly focus on modes of action and effects of androgens and estrogens on sex differentiation and gonadal development in various model fish species.