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Trenbolone causes mortality and altered sexual differentiation in Xenopus topicalis during larval development
Citation:
OLMSTEAD, A. W., P. A. KOSIAN, R. D. JOHNSON, P. BLACKSHEAR, J. HASELMAN, C. BLANKSMA, J. J. KORTE, G. W. HOLCOMBE, E. BURGESS, A. LINDBERG-LIVINGSTON, B. BENNETT, K. K. WOODIS, AND S. J. DEGITZ. Trenbolone causes mortality and altered sexual differentiation in Xenopus topicalis during larval development . ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 31(10):2391-2398, (2012).
Impact/Purpose:
To document research results
Description:
Trenbolone is a non-aromatizeable androgen agonist used extensively in the beef industry. It can be excreted from cattle in an active form and has been measured in aquatic systems associated with or near concentrated animal feeding operations. We characterized the effects of aqueous exposure to 17â-trenbolone during larval Xenopus tropicalis development. Trenbolone exposure resulted in increased mortality of post-NF stage 58 tadpoles at concentrations =100 ng/L. Necropsies of these mortalities showed deflated lungs and air present within the digestive tract. These morphological observations and the timing of this mortality are consistent with the larynx becoming hypertrophic following the onset of androgen sensitivity. Development of nuptial pads, a male secondary sex characteristic, was induced in newly metamorphed tadpoles of both sexes at 100 ng/L. Effects on time to complete metamorphosis or body sizes were not observed; however, grow-outs placed in clean media for six weeks had significantly smaller wet weights and snout-vent lengths at 78 ng/L. Effects on sex ratios were equivocal, with the first experiment showing a significant shift in sex ratio towards males at 78 ng/L and in the second experiment, no significant effects were observed up to 100 ng/L, although the overall sex ratios were similar. Histological assessment of gonads at the completion of metamorphosis (NF stage 66) at 100 ng/L showed half with normal male phenotypes and half that possessed some degree of a mixed sex phenotype. Hypertrophy of the Wolffian ducts was also observed at the 100 ng/L exposure level. These results indicate that larval 17â-trenbolone exposure results in toxicity with a LOEC of 78 ng/L and illustrate the risks of exposure to chemicals possessing androgenic activity in anuran species.
