title: Testosterone metabolism in the estuarine mysid Neomysis integer (Crustacea; Mysidacea) following tributyltin exposure.
abstract: Current evidence suggests that the biocide tributyltin (TBT) causes the development of imposex, a state of pseudohermaphrodism in which females exhibit functional secondary male characteristics, by altering the biotransformation or elimination of testosterone. Imposex in gastropods following TBT exposure is the most complete example of the effects of an endocrine disrupter on marine invertebrates. Previous studies have demonstrated that the estuarine mysid Neomysis integer converts testosterone into multiple polar and nonpolar metabolites resulting from both phase I and phase II biotransformations. In this study, the effects of TBT chloride (TBTCl) on the phase I and II testosterone metabolism of N. integer were evaluated. The TBTCl was highly toxic to N. integer (96-h median lethal concentration [LC50] of 164 ng/L). To assess the effects on testosterone metabolism, mysids were exposed for 96 h to different concentrations of TBTCl (control, 10, 100, and 1,000 ng/L), and testosterone elimination as polar hydroxylated, nonpolar oxido-reduced, and glucose- and sulfate-conjugated metabolites was examined. The TBTCl differentially affected testosterone metabolism. The effect of TBTCl on phase I metabolism was unclear and has been shown to vary among species, likely depending on the inducibility or presence of certain P450 isozyme families. Reductase activity and metabolic androgenization were induced in the 10-ng/L treatment, whereas higher concentrations resulted in a reduction of sulfate conjugation. The exact mechanisms underlying TBT-induced imposex and alterations in the steroid metabolism need to be further elucidated.
authors.affiliation: Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent, Belgium. tim.verslycke@rug.ac.be
authors.forename: Tim
authors.initials: T
authors.lastname: Verslycke
authors.forename: Sofie
authors.initials: S
authors.lastname: Poelmans
authors.forename: Katia
authors.initials: K
authors.lastname: De Wasch
authors.forename: Jordy
authors.initials: J
authors.lastname: Vercauteren
authors.forename: Christophe
authors.initials: C
authors.lastname: Devos
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Patrick
authors.initials: P
authors.lastname: Sandra
authors.forename: Hubert F
authors.initials: HF
authors.lastname: De Brabander
authors.forename: Colin R
authors.initials: CR
authors.lastname: Janssen
mesh_terms: D000818:Animals; D003445:Crustacea / Q000502:physiology*; D003577:Cytochrome P-450 Enzyme System / Q000494:pharmacology; D012734:Disorders of Sex Development / Q000139:chemically induced*; D004703:Endocrine System / Q000187:drug effects; D005260:Female; D007928:Lethal Dose 50; D008297:Male; D013739:Testosterone / Q000378:metabolism*; D014220:Trialkyltin Compounds / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014220:Trialkyltin Compounds; D014874:Water Pollutants, Chemical; D013739:Testosterone; C011559:tributyltin; D003577:Cytochrome P-450 Enzyme System