Lanham, K.A., Peterson, R.E., and Heideman, W. (2012) Sensitivity to Dioxin Decreases as Zebrafish Mature. Toxicological sciences : an official journal of the Society of Toxicology. 127(2):360-370.
The embryos of teleost fish are exquisitely sensitive to the toxic effects of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However, several lines of evidence suggest that adults are less sensitive to TCDD. To better understand and
characterize this difference between early life stage and adults, we exposed zebrafish (Danio rerio) to graded TCDD concentrations at different ages. The LD50 for embryos exposed at 1 day post fertilization (dpf) was more than an order of magnitude lower than it was for juveniles
exposed at 30 dpf. The latency between exposure and response also increased with age. Embryo toxicity was characterized by
marked cardiovascular collapse and heart malformation, while juveniles exposed at 30 dpf had no detectable cardiovascular
toxicity. In juveniles the effects of TCDD exposure included stunted growth, altered pigmentation, and skeletal malformations.
Furthermore, the transcriptional profile produced in hearts exposed to TCDD as embryos had very little overlap with the transcriptional
changes induced by TCDD at 30 dpf. The early cardiotoxic response was associated with fish exposed prior to metamorphosis
from the larval to the adult body plan at approximately 14 dpf. Our results show conclusively that the developmental stage
at the time of exposure controls the toxic response to TCDD.