Postmetamorphic Xenopus laevis shows decreased plasma triiodothyronine concentrations and phosphorylase activity due to subacute phytosterol exposure

• Published in: Chemosphere (Oxford) Vol. 57; no. 11; pp. 1683 - 1689
• Main Authors: Koponen, Petri S., Nieminen, Petteri, Mustonen, Anne-Mari, Kukkonen, Jussi V.K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2004; Elsevier
• Subjects: Animal, plant and microbial ecology; Animals; Anura; Applied ecology; beta-sitosterol; Biological and medical sciences; campestanol; campesterol; Ecotoxicology, biological effects of pollution; enzyme activity; Female; Fundamental and applied biological sciences. Psychology; General aspects; glycogen; Glycogen - metabolism; Lipase; Liver - drug effects; Liver - enzymology; Male; Muscles - drug effects; Muscles - enzymology; phosphorylase; Phosphorylases - metabolism; Phytosterol; phytosterols; Phytosterols - toxicity; sitostanol; subacute toxicity; Testosterone; Testosterone - blood; Thyroid hormone; thyroid hormones; Thyroid Hormones - blood; triacylglycerol lipase; triiodothyronine; Triiodothyronine - blood; Xenopus laevis; Xenopus laevis - blood; Xenopus laevis - metabolism; Testosterone; Thyroid hormone; Lipase; Xenopus laevis; Phytosterol; Plasma; Enzyme; Transferases; Glycosyltransferases; Amphibia; Triacylglycerol lipase; Esterases; Salientia; Phosphorylase; Carboxylic ester hydrolases; Vertebrata; Hydrolases; Hexosyltransferases; Triiodothyronine; Subacute
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2004.07.029

Postmetamorphic South African clawed frogs ( Xenopus laevis) were exposed to a phytosterol mixture (ca. 80% β-sitosterol and less sitostanol, campesterol, and campestanol) for 14 days at 30 μg l −1 in a flow-through system. The effects of phytosterols (PS) on the plasma thyroid hormone (T 3 and T 4), testosterone, leptin-immunoreactive peptide and tissue glycogen concentrations were determined. The following enzyme activities were also analyzed from the liver and muscle: glycogen phosphorylase and lipase, and from the liver only: glucose-6-phosphatase. The plasma T 3 concentration was lower in the PS-exposed female frogs. Both muscle lipase and glycogen phosphorylase activities were also lower in the PS-exposed animals. These results could indicate that the basal metabolic rate and locomotion activity of the frogs were decreased. The effects could not be attributed to the possible estrogenicity of the PS mixture. Further studies will be needed to evaluate the possible significance of these effects.