High induction of cytochrome p4501a activity without changes in retinoid and thyroid hormone levels in flounder (Platichthys flesus) exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin
✍ Scribed by H. T. Besselink; E. van Santen; W. Vorstman; A. D. Vethaak; J. H. Koeman; A. Brouwer
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 92 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0730-7268
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✦ Synopsis
Oral doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were administered twice within 7 d (total concentration 0.01, 0.1, 1, 10, or 100 g TCDD/kg body weight) to flounder (Platichthys flesus). After 10 d of exposure, flounder were sacrificed, and the effects of TCDD exposure on hepatic microsomal total cytochrome P450 content, 7-ethoxyresorufin-O-deethylase (EROD) activity, and glutathione-S-transferase activity were examined. In addition, plasma and hepatic retinoid and plasma thyroid hormone levels were analyzed. Overall a good correlation existed between the dose and liver concentrations of TCDD. However, only 0.75% of the total dose of TCDD was retained in the flounder liver. The TCDD caused a dose-related, statistically significant induction of the hepatic microsomal total cytochrome P450 content (4.4-fold; p Ͻ 0.001) and associated EROD activity (27-fold; p Ͻ 0.001), without obvious changes in body weight, liver weight, and condition factor. Total glutathione-S-transferase activity was not induced in livers of flounder exposed to TCDD. No TCDD-induced changes in liver retinoid, plasma retinol, and plasma thyroid hormone parameters were observed. These results indicate that the flounder is an aryl hydrocarbon (Ah) receptor-responsive species with respect to CYP1A induction but not with respect to other mammalian Ah receptor-associated responses.