Meeting Abstract

P2.53  Tuesday, Jan. 5  Effects of Environmental Estrogens on the Growth Hormone-Insulin-Like-Growth Factor System and Seawater Adaptation of Rainbow Trout HANSON, A.M.*; SHERIDAN, M.A.; North Dakota State Univ., Fargo; North Dakota State Univ., Fargo andrea.m.hanson@ndsu.edu

Previous studies show that successful adaptation of euryhaline teleost fish to seawater (SW) involves the GH-IGF system. Fish in aquatic habitats are exposed to increasing concentrations of environmental contaminants, including environmental estrogens (EE). In this study, we used rainbow trout (Oncorhynchus mykiss) to assess the effects of EE on the GH-IGF system and seawater adaptation. Juvenile trout (ca. 30g) were exposed to either low (10 µg/l) or high (100 µg/l) concentrations of β-sitosterol (BS), 4-n-nonylphenol (NP), or 17β-estradiol (E2) for 28 days in fresh water (FW) (14 C; 12L:12D), then half of the fish were exposed to 20‰ SW while the other half remained in FW. A slight elevation in plasma chloride levels accompanied by a slight depression in gill Na+,K+-ATPase activity was observed in all EE-treated fish compared to control fish 6-12 h after SW exposure. SW increased hepatic mRNA levels of GH receptor 1 (GHR1), GHR2, IGF-1, and IGF-2 in control fish 6-12 h after exposure. In gill, levels of GHR1, GHR2, IGF-1, IGF-2, IGF receptor 1A (IGFR1A) and IGFR1B mRNAs also increased in control fish 6-12 h after SW exposure. Exposure to BS, NP, and E2 abolished or attenuated normal SW-induced changes in the expression of GHR, IGF, and IGFR1 mRNAs in liver and gill. These results indicate that EE reduces SW adaptability by inhibiting the GH-IGF system. (Supported by NSF IOS 0920116)