Although organotin compounds are known to disturb thyroid signaling and antioxidant defense system, the sex-differences underlying these effects of triphenyltin chloride (TPT) in fish remain unclear. To understand these differences, adult zebrafish (Danio rerio) were exposed to different concentrations of TPT (0, 10, 100, or 1000 ng/L) for 28 days. Female zebrafish exposed to TPT showed significantly increased thyroxine (T4) content and decrease triiodothyronine (T3) content, possibly due to downregulation of deiodinase (dio2) and uridine diphosphate glucuronosyl transferase (ugt1ab). However, decreased T4 and T3 contents in male zebrafish accompanied with upregulation of dio1, dio2 and ugt1ab. TPT exposure can lead to sex-specific thyroid disruption in adult zebrafish via alterations the Hypothalamus-pituitary-thyroid-liver axis. In addition, the gene expression levels of metabolizing enzymes, such as cyp1b, cyp1c, gpx1a, or sult1st1 were also to vary in a sex-dependent manner in adult zebrafish liver. Downregulation of cyp19a and cyp19b and decreased 17β-estradiol (E2) contents were detected in both female and male zebrafish. Therefore, a sex-specific of thyroid disruption response after TPT exposure was observed in adult zebrafish, possibly due to inherent in female or males detoxifying enzyme capacities.
Keywords: Hypothalamus-pituitary-thyroid-liver (HPTL) axis; Metabolizing enzymes; TPT; Thyroid disruption.
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