Development of anin vivoanti-androgenic activity detection assay using fenitrothion in Japanese medaka (Oryzias latipes)

Abstract

The effects of endocrine disruptors, including anti-androgenic chemicals, on aquatic environments have received increased attention in recent years. Currently, the method used to screen chemicals for anti-androgenic activity is called the androgenized female stickleback screen, and it was established by the Organization of Economic Cooperation and Development in 2011 using the three-spined stickleback. However, screening chemicals for anti-androgenic activity has yet to be established using Japanese medaka. Thus, the purpose of this study was to establish a screening method for anti-androgenic activity utilizing the number of papillary processes in Japanese medaka (Oryzias latipes) as an indicator of the chemical's anti-androgenic activity. Thus, at 35 days post-fertilization, medaka were exposed to fenitrothion, an anti-androgenic compound, for 28 days. In the control group, the formation of papillary processes was observed in XY medaka, but not in XX medaka. However, after fenitrothion exposure, the number of papillary processes was significantly decreased in a dose-dependent manner in XY medaka; in the 300 μg l concentration group, four of 11 XY medaka showed no papillary processes even if there were no significant effects on total length and wet body weight compared with the control group. Our results indicate that the number of papillary processes in Japanese medaka can be used as an indicator of anti-androgenic activity and that this model may prove useful as a chemical screening method. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of triclosan on Japanese medaka (Oryzias latipes) during embryo development, early life stage and reproduction

“…After exposure, the fish were analyzed as described previously (Horie, Watanabe et al, ). Briefly, fish were anesthetized with tricaine methanesulfonate (MS‐222; Sigma‐Aldrich, St. Louis, MO, USA) at a standard concentration.…”

“…Water quality and triclosan concentration in the test solutions were assessed during the test period as described previously (Horie, Watanabe et al, ). The water quality of each test solution was determined once per week by using a thermometer (CT‐430WP; Custom, Tokyo, Japan), a pH meter (D‐55; Horiba, Kyoto, Japan), and a dissolved oxygen meter (HQ30d; Hach, Loveland, CO, USA); the average values of the parameters for all of the tanks over the whole experimental period were temperature 25 ± 2 °C, pH 7.5 ± 0.5 and dissolved oxygen ≥60% oxygen saturation.…”

“…After exposure, the fish were analyzed as described previously (Horie, Watanabe et al, 2017). Briefly, fish were anesthetized with tricaine The concentration of vitellogenin in the liver was determined by using an enzyme-linked immunosorbent assay (EnBio Medaka Vitellogenin enzyme-linked immunosorbent assay system; Fujikura Kasei, Tokyo, Japan), in accordance with the manufacturer's protocol.…”

Medaka extended one‐generation reproduction test evaluating 4‐nonylphenol

“…In the National Institute for Environmental Studies strain used in the present study, anal fin papillae begin to appear in male fish at approximately 7 wpf (43 dpf). By 64 dpf, with a total length of 26 mm, the mean number of plates with papillary processes was 66 AE 5 [23]; by 68 dpf the mean number of plates was 81 to 88 AE 19 to 12 [41]. In the present study, the total length of subadult fish at 64 to 65 dpf was 21.2 mm in controls and 18.6 mm at 89.4 mg/L NP, slightly smaller than those in previous studies [23,41].…”

“…By 64 dpf, with a total length of 26 mm, the mean number of plates with papillary processes was 66 AE 5 [23]; by 68 dpf the mean number of plates was 81 to 88 AE 19 to 12 [41]. In the present study, the total length of subadult fish at 64 to 65 dpf was 21.2 mm in controls and 18.6 mm at 89.4 mg/L NP, slightly smaller than those in previous studies [23,41]. This suggests that reduction of the anal fin papillae could be induced not only by the estrogenic activity of NP but also by the delayed sexual development.…”