Vitellogenin-induced pathology in male summer flounder (Paralichthys dentatus)

Male summer flounder (Paralichthys dentatus) were given two injections (ini tially and 2 weeks later) of 17 beta -estradiol (E2) totaling 0.2 (2 x 0.1) , 2.0 (2 x 1.0) or 20.0 (2 x 10.0) mg E2/kg body weight. Blood and tissue s amples were collected 4, 6 and 8 weeks after the initial injection in the ( 2 x 0.1) mg/kg treatment, 4, 6, 8, and 15 weeks after the first injection i n the (2 x 1.0) mg/kg treatment and at 4 weeks only in the (2 x 10.0) mg/kg treatment. Five of the 12 fish injected twice with 10.0 mg/kg were moribun d before the first sampling period. Circulating levels of vitellogenin (VTG ) in the blood of all E2-injected fish from all treatments were comparable with those concentrations found in the blood of wild male carp (Cyprinus ca rpio) and walleye (Stezostedion vitreum) previously collected near a sewage treatment plant (0.1-10.0 mg VTG/ml plasma). Excessive hyalin material acc umulated in the livers, kidneys and testes of the treated fish. A portion o f that material was identified as VTG by immunohistochemistry. The accumula tion of VTG, and possibly other estrogen-inducible proteins, resulted in he patocyte hypertrophy, disruption of spermatogenesis, and obstruction or rup ture of renal glomeruli. Published by Elsevier Science B.V.