KITANA, N.*; WON, S.J.; CALLARD, I.P.; Boston University; Boston University; Boston University: Environmental and hormonal impacts on reproduction and development in the freshwater turtles

Previous observations on the freshwater turtle (Chrysemys picta) obtained from a Superfund site on Cape Cod, MA suggested endocrine disruption of reproductive processes. To determine the possible loci in the hypothalamic-pituitary-gonadal-hepatic axis that may be disrupted, animals from the impacted (Moody Pond) and control (Washburn Pond) sites were subjected to hormonal challenges. Ovine FSH (0.1 NIH unit/animal sc) and estradiol 17β (1 mg/kg sc) responses were assessed using radioimmunoasay of plasma steroids and vitellogenin by homologous ELISA. Basal vtg levels were significantly lower in Moody Pond females than Washburn females. However, vtg responses after estradiol injection were not significantly different, suggesting a normal hepatic response in the presence of adequate estrogen. Responses to FSH in males and females were assessed at 0, 1, 4, 24, 48 and 96 hours. In males, basal plasma testosterone levels were similar; but the steroid response to FSH was blunted and attenuated in Moody compared to Washburn animals (p<0.05, at 24-hrs). The slower return of plasma steroids from peak to baseline and lesser response suggests possible interference in steroid synthetic and/or catabolic pathways in the Moody Pond animals. In laboratory studies, we have sought to replicate the field observations. Juvenile Trachemys scripta, a closely related species, were maintained for 9 months in laboratory aquaria using pond sediment and pond water as variables. Assessment of hepatic CYP1A1 expression, gonial proliferation, gonial apoptosis and gametogenesis is in progress. Overall, the new data support prior studies suggesting that low level xenobiotic contaminants may interfere with the HPG-liver axis or the processes of gametogenesis. [Supported by ES 077381 to IPC and an educational grant from the Thai Government to NK]