Chronic exposure to dietary selenomethionine increases gonadal steroidogenesis in female rainbow trout

• Published in: Aquatic toxicology Vol. 105; no. 3; pp. 218 - 226
• Main Authors: Wiseman, Steve, Thomas, Jith K., Higley, Eric, Hursky, Olesya, Pietrock, Michael, Raine, Jason C., Giesy, John P., Janz, David M., Hecker, Markus
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2011; Elsevier
• Subjects: androstenedione; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; blood plasma; Chromatography, High Pressure Liquid; chronic exposure; cytochrome P-450; dietary exposure; Ecotoxicology, biological effects of pollution; Endocrine Disruptors - analysis; Endocrine Disruptors - toxicity; endocrine system; enzymes; Estradiol; estrone; Female; females; follicle-stimulating hormone; Food Contamination - analysis; Fundamental and applied biological sciences. Psychology; General aspects; Gonadal Steroid Hormones - blood; Gonadotropin; Gonadotropins - metabolism; luteinizing hormone; Metalloid; Oncorhynchus mykiss; Oncorhynchus mykiss - metabolism; Ovary - drug effects; Ovary - metabolism; Polymerase Chain Reaction; Random Allocation; Receptors, Estrogen - metabolism; Receptors, Gonadotropin - metabolism; Selenium; selenomethionine; Selenomethionine - analysis; Selenomethionine - toxicity; Steroid hormone; steroid hormones; steroidogenesis; Tandem Mass Spectrometry; testosterone; thyroid hormones; Vitellogenesis; Vitellogenesis - drug effects; vitellogenin; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - toxicity; Vitellogenesis; Gonadotropin; Selenium; Metalloid; Steroid hormone; Estradiol; Ecotoxicology; Toxicity; Oncorhynchus mykiss; Feeding; Aquatic environment; Vertebrata; Chronic; Diet; Gonad; Pisces; Female; Steroidogenesis
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2011.06.012

Selenomethionine (Se-Met) is the major dietary form of selenium (Se). Detrimental effects have been associated with exposure to elevated dietary selenium. Previous studies have demonstrated effects of Se on the endocrine system, in particular effects on cortisol and thyroid hormones. However, no information is available regarding effects of Se on sex steroid hormones. In the present study, effects of dietary exposure to an environmentally relevant concentration (4.54 mg/kg wet weight (ww)) of Se-Met for 126 days on concentrations of sex steroid hormones in blood plasma of female rainbow trout were determined. Furthermore, the molecular basis for effects of Se-Met on plasma sex steroid hormone concentrations was investigated. Concentrations of androstenedione (A), estrone (E1), and estradiol (E2) were 39.5-, 3.8-, and 12.7-fold greater in plasma of treated females than the untreated controls, respectively. Testosterone (T) was detected only in plasma of treated females. The greater E2 concentration stimulated greater transcript abundance of vitellogenin ( vtg) and zona-radiata protein ( zrp). Female rainbow trout exposed to Se-Met had greater transcript abundance of key steroidogenic proteins and enzymes, including peripheral benzodiazepine receptor ( pbr), cytochrome P450 side-chain cleavage ( P450scc), and 3β-hydroxysteroid dehydrogenase (3β- hsd). Exposure to Se-Met did not affect transcript abundance of luteinizing hormone ( lh) or follicle stimulating hormone ( fsh). Similarly, there was no change in transcript abundance of luteinizing hormone receptor ( lhr) or follicle stimulating hormone receptor ( fshr). Long-term exposure to dietary Se-Met has the potential to stimulate vitellogenesis in female rainbow trout by directly stimulating ovarian tissue steroidogenesis. This is the first study to report effects of Se on sex steroid hormone production in fish.