Effects of estrogenic (o,p '-DDT; octylphenol) and anti-androgenic (p,p '-DDE) chemicals on indicators of endocrine status in juvenile male summer flounder (Paralichthys dentatus)

Laboratory experiments were conducted with male summer flounder to assess t he Value of selected measures of endocrine status in fish as indicators of exposure to endocrine-disrupting contaminants. Effects of 1,1,1-trichloro-2 -(p-chlorophenyl)-2-(o-chlorophenyl) ethane (o,p'-DDT), octylphenol and 1,1 -dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) on hepatosomatic and gonadosomatic indices, plasma steroid hormone levels, vitellogenin product ion: and gonadal development were evaluated in laboratory-raised, juvenile male summer flounder. Flounder were injected twice with test chemical in a coconut oil carrier. Each chemical was tested at three different concentrat ions. Estrogenic (o,p'-DDT; octylphenol) and anti-androgenic (p,p'-DDE) che micals were evaluated alone and in combination (octylphenol plus o,p'-BDT o r p,p'-DDE). Additionally, some fish were treated with the natural ligand f or the estrogen receptor, 17 beta -estradiol. Blood and tissues from differ ent fish in each treatment were sampled 4, 6 and 8 weeks after the first in jection. Fish exposed to a combination of o,p'-DDT plus octylphenol were al so sampled after 15 weeks. In all cases, responses of fish exposed to a tes t chemical were compared to control fish sampled at the same time. The foll owing significant differences, relative to controls, were observed in at le ast one sampling time or at least one concentration of chemical. 17 beta -E stradiol-treated flounder exhibited decreased gonadosomatic index (GSI), al tered hepatosomatic index (HSI), elevated plasma estradiol, reduced plasma testosterone, and high levels of plasma vitellogenin. Fish treated with o,p '-DDT showed lower GSI, no change in HSI or plasma estradiol, depression of plasma testosterone. and induction of vitellogenesis. Octylphenol treatmen t resulted in lower GSI, no change in HSI, initially increased plasma estra diol and decreased testosterone, and no vitellogenin production. p,p'-DDE t reatment did not significantly alter any indicator relative to controls. In experiments using combinations of chemicals, flounder receiving o,p'-DDT p lus octylphenol had lower GSI after 8 weeks and elevated plasma estradiol a fter 15 weeks exposure. Fish treated with p,p'-DDE plus octylphenol for 8 w eeks exhibited a significantly lower GSI. Overall, lon er GSI and plasma te stosterone levels, relative to controls, were consistent indicators of expo sure to estrogenic chemicals in juvenile male flounder. No indicators were found that would identify exposure to the mammalian anti-androgen p,p'-DDE. Published by Elsevier Science B.V. All rights reserved.