Effect of 17beta-estradiol, o,p'-DDT, octylphenol and p,p'-DDE on gonadal development and liver and kidney pathology in juvenile male summer flounder (Paralichthys dentatus).

The intent of this study was to compare histopathologically the effect of 17beta-estradiol (E(2)), o,p'-DDT, octylphenol and p,p'-DDE on gonadal development and liver and kidney condition in sexually immature (juvenile) summer flounder (Paralichthys dentatus). The dorsal sinus of 2-year-old juvenile male summer flounder was injected with the appropriate amount of chemical incorporated in coconut oil. A second identical injection was administered 2 weeks later. Fish were sampled at 4, 6 and 8 weeks after the initial injection and observed histopathologically. In control fish, spermatogenesis was predominantly in mid to late maturation. In fish treated with 1.0 and 10.0 mg/kg E(2) spermatogenesis regressed to primary spermatogonia or an immature functional state. Testicular atrophy and spermatogonial proliferation was also observed. An eosin-positive, hyaline material was found in the gonad, liver and kidney. This eosinophilic material also stained positive with Periodic Acid Schiff (PAS) stain. Treatment of 30 or 60 mg/kg o,p'-DDT elicited altered gonadal development similar to that observed with E(2) treated fish. Octylphenol treatment of 100 mg/kg resulted in reduced testicular size, ducts full of sperm, numerous spermatogonia and PAS positive material in the testis with no developing sperm cysts. No effect on liver or gonad tissues was observed with p,p'-DDE at the concentrations tested. All chemicals tested, with exception of p,p'-DDE, altered gonadal development, whereas only E(2) caused histopathological changes in the liver and kidney. Estrogenic activity induced the liver to produce a vitellogenin (VtG)-like substance and inhibited testicular maturation. As a result, both the lack of target cells for VtG and a continuous supply of VtG from the liver allowed the hyaline material to accumulate in the liver, testis and kidney causing histopathological changes.

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

Male summer flounder (Paralichthys dentatus) were given two injections (initially and 2 weeks later) of 17beta-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 samples 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 in 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 moribund 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 carpio) and walleye (Stezostedion vitreum) previously collected near a sewage treatment plant (0.1-10.0 mg VTG/ml plasma). Excessive hyalin material accumulated in the livers, kidneys and testes of the treated fish. A portion of that material was identified as VTG by immunohistochemistry. The accumulation of VTG, and possibly other estrogen-inducible proteins, resulted in hepatocyte hypertrophy, disruption of spermatogenesis, and obstruction or rupture of renal glomeruli.