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Alteration of [14C]-Testosterone Metabolism After Chronic Exposure of Daphnia magna to Tributyltin

Alteration of [14C]-Testosterone Metabolism After Chronic Exposure of Daphnia magna to Tributyltin Tributyltin (TBT) is a marine biocide that has been shown to alter the activity of cytochrome P450 monooxygenases and elicit toxicity indicative of androgenization in some species. The present study was conducted to determine whether TBT altered P450-, reductase-, and transferase-mediated testosterone metabolic processes in Daphnia magna at sublethal exposure concentrations. Two generations of daphnids were continuously exposed for 21 days to nominal TBT concentrations ranging from 0.31 to 2.5 μg/L TBT. The highest TBT concentration (2.5 μg/L) was lethal to 60% of the exposed organisms. Lower TBT concentrations elicited no adverse effects on molting or reproduction of the daphnids. No differences were observed in the response of the first- and second-generation daphnids to the toxicity of TBT. The ability of daphnids to metabolize [14C]-testosterone in vivo was assessed following exposure of each generation to TBT. Production of hydroxylated, reduced/dehydrogenated, and glucose-conjugated metabolites of testosterone were all elevated following exposure of both generations to 1.25 μg/L TBT. These findings indicate that, under these conditions, TBT elicits no discernible effects on molting and reproduction of daphnids at sublethal concentrations, and testosterone metabolism is enhanced at concentrations approaching those that are lethal to organisms. Alterations of steroid metabolism by xenobiotics can be used as a more sensitive indicator of sublethal exposure in daphnids than reproductive endpoints. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Environmental Contamination and Toxicology Springer Journals

Alteration of [14C]-Testosterone Metabolism After Chronic Exposure of Daphnia magna to Tributyltin

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References (15)

Publisher
Springer Journals
Copyright
Copyright © 1998 by Springer-Verlag New York Inc.
Subject
Environment; Ecotoxicology; Pollution, general; Environmental Health; Environmental Chemistry; Soil Science & Conservation; Environmental Monitoring/Analysis
ISSN
0090-4341
eISSN
1432-0703
DOI
10.1007/s002449900281
Publisher site
See Article on Publisher Site

Abstract

Tributyltin (TBT) is a marine biocide that has been shown to alter the activity of cytochrome P450 monooxygenases and elicit toxicity indicative of androgenization in some species. The present study was conducted to determine whether TBT altered P450-, reductase-, and transferase-mediated testosterone metabolic processes in Daphnia magna at sublethal exposure concentrations. Two generations of daphnids were continuously exposed for 21 days to nominal TBT concentrations ranging from 0.31 to 2.5 μg/L TBT. The highest TBT concentration (2.5 μg/L) was lethal to 60% of the exposed organisms. Lower TBT concentrations elicited no adverse effects on molting or reproduction of the daphnids. No differences were observed in the response of the first- and second-generation daphnids to the toxicity of TBT. The ability of daphnids to metabolize [14C]-testosterone in vivo was assessed following exposure of each generation to TBT. Production of hydroxylated, reduced/dehydrogenated, and glucose-conjugated metabolites of testosterone were all elevated following exposure of both generations to 1.25 μg/L TBT. These findings indicate that, under these conditions, TBT elicits no discernible effects on molting and reproduction of daphnids at sublethal concentrations, and testosterone metabolism is enhanced at concentrations approaching those that are lethal to organisms. Alterations of steroid metabolism by xenobiotics can be used as a more sensitive indicator of sublethal exposure in daphnids than reproductive endpoints.

Journal

Archives of Environmental Contamination and Toxicology – Springer Journals

Published: Jan 8, 2016

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