The impact of cadmium on estradiol uptake in amphibian embryos

OSVALDO FRIDMAN; ARONZON C. M.; HERKOVITS J

Congreso; VI Congreso Society of Environmental Toxicology and Chemistry (SETAC) Rama Latinoamérica. “Salud Ambiental y Humana: Una Visión Holística”; 2003

The effect of cadmium on estradiol bioconcentration in Bufo arenarum embryos. Endocrine disrupters represent a major threat to wildlife as well as human health with special impact on early life stages. On the other hand living organisms are exposed to a large number of physico-chemical agents which exert in many cases toxic effects. Cadmium is among the usual pollutants in many environmental scenarios due anthropogenic activities. In previous studies we reported that in amphibian embryos cadmium toxicity was enhanced by estradiol (E2), pointing out that endocrine disrupters can also impact on metal toxicity. Moreover this effect occur in E2 concentrations e.g. (1 or 10 µM) which have not toxic effect by itself in the amphibian embryos. In this study we explore the effect of cadmium in low level and sub lethal exposure conditions on the uptake of E2 in Bufo arenarum embryos. For this purpose 20 embryos by duplicate at stage 25 (complete operculum) were treated during 13 days according to the following conditions: A) 0.1 mg/L Cd and B) an acclimation protocol starting with 0.01 mgCd2+/L increased gradually every other day up to a final concentration of 0.046 mg Cd/L.C: Control embryos were maintained in AMPHYTOX Solution (AS) without additions. Then, for the E2 uptake study, the experimental and control embryos were maintained during 3 hr in 10 µM E2 plus 1 µCi 3H-E2. After homogenization of the biological material the radioactivity of the whole embryos were measured with a Beckman scintillation spectrophotometer and the E2 uptake was calculated as a function of the radioactive versus no radioactive E2 in the media and the embryos in each sample. The concentrations of E2 in the embryos were: A:23.7 (1.29),B: 16.0 (1.48) and C:14.8 (0.34) ng E2/mg embryo. The results point out an increase in the E2 uptake in the cadmium treated embryos which resulted significant in the case of the sub lethal exposure condition (p < 0.01). Therefore the adverse effect of E2 on metal toxicity could be enhanced by the increased uptake of E2 in organisms exposed to the metal under the more aggressive treatment.