The juvenile three-spined stickleback (Gasterosteus aculeatus L.) as a model organism for endocrine disruption II--kidney hypertrophy, vitellogenin and spiggin induction.

This study investigated the suitability of juvenile three-spined sticklebacks, Gasterosteus aculeatus L., for detecting both androgen- and oestrogen-induced endocrine disruption. The investigated endpoints were kidney hypertrophy and the induction of the protein markers spiggin and vitellogenin. Juveniles were exposed to steroid hormones 17 beta-oestradiol (E2: nominal 0.01, 1.0 and 10 microg/L), 17 alpha-ethinylestradiol (EE2: nominal 0.05 microg/L) and 17 alpha-methyltestosterone (MT: nominal 1.0 microg/L) from the day of hatching until the termination of the experiments between 39 and 58 days after hatching. E2 (10 microg/L) and MT were applied during different time windows: (a) 14 days after hatching only and (b) continuously with start 14 days after hatching. Kidney hypertrophy is an androgen-dependent secondary sexual character in adult male sticklebacks and corresponds to the production of the glue protein spiggin during the breeding season. The kidneys were hypertrophied and spiggin levels were elevated in juvenile sticklebacks after treatment with MT. Paradoxically, slightly elevated spiggin levels and kidney hypertrophy were observed also in fish treated with high dose E2. Levels of vitellogenin, the oestrogen-inducible yolk precursor protein, were elevated in juvenile sticklebacks after E2 medium and high dose and EE2 treatment. The tested endpoints are suitable for the study of endocrine disruption in juvenile sticklebacks, a fish species that is easy to handle in laboratory and relevant for temperate geographical regions.