Benzo[a]pyrene effects on reproductive endpoints in Fundulus heteroclitus

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon (PAH) that has been implicated in modulating aromatase enzyme function with the potential to interrupt normal reproductive function. The aim of this study was to use a fish model, Fundulus heteroclitus, to assess whether BaP exposure adversely impacts reproduction. Adult fish were exposed to waterborne BaP nominal concentrations of (0, 1, or 10 μg/l) for 28 days. Males and females were combined for the second half of the exposure (days 14-28) in order to quantitate egg production and fertilization success. Egg fertilization and subsequent hatching success of F1 embryos was significantly decreased by the high dose of BaP. In males, both gonad weight and plasma testosterone concentrations were significantly reduced compared to controls by 10 μg/l BaP. Histopathological examination of testes including spermatogonia, spermatocyte and spermatid cyst areas, percentage of cysts per phase, and area of spermatozoa per seminiferous tubule were not significantly affected. Other biomarkers, including male liver weight, liver vitellogenin (vtg) mRNA expression and sperm concentrations, were also not affected. In females, estradiol concentrations were significantly reduced after BaP exposure, but egg production, gonad weight, liver weight, vtg expression and oocyte maturation were not altered. Steroid concentrations in Fundulus larvae from exposed parents at 1 and 3 weeks posthatch were not significantly changed. BaP exposure at these environmentally relevant concentrations caused negative alterations particularly in male fish to both biochemical and phenotypic biomarkers associated with reproduction and multigenerational embryo survival.