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Title: Hepatic indices of thyroid status in rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Authors: Kelling, C K; Menahan, L A; Peterson, R E

Published In Biochem Pharmacol, (1987 Jan 15)

Abstract: The functional thyroid status of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-treated rats is unknown. Therefore, activities of certain thyroid-responsive enzymes were examined in the livers of adult male Sprague-Dawley rats 1 week after treatment with TCDD (6.25, 25 or 100 micrograms/kg). Activity of the thyroid-responsive flavin L-glycerol-3-phosphate dehydrogenase (per mg mitochondrial protein) was decreased slightly in livers of TCDD-treated rats, while that of succinate dehydrogenase remained unchanged. In contrast, activities (per mg supernatant protein) of three thyroid-responsive NADP-dependent cytosolic enzymes, malic enzyme, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, were increased by TCDD treatment in a dose-dependent manner. Lactate dehydrogenase (activity per mg supernatant protein) was also augmented slightly 1 week after TCDD administration. Liver mass was increased by TCDD treatment in a dose-dependent manner, but DNA content per liver was similar at all doses examined. Total hepatic protein, expressed per liver or mg hepatic DNA, was increased in TCDD-treated rats when compared to their pair-fed counterparts. The decreased activity of the mitochondrial L-glycerol-3-phosphate dehydrogenase, in contrast to the increased activities of the supernatant enzymes, malic enzyme, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, is not consistent with a shift in functional thyroid status following TCDD treatment.

PubMed ID: 3814171 Exiting the NIEHS site

MeSH Terms: Animals; DNA/metabolism; Dioxins/pharmacology*; Glucosephosphate Dehydrogenase/metabolism; Glycerolphosphate Dehydrogenase/metabolism; Kinetics; L-Lactate Dehydrogenase/metabolism; Liver/drug effects*; Liver/metabolism; Male; Organ Size/drug effects; Phosphogluconate Dehydrogenase/metabolism; Polychlorinated Dibenzodioxins/pharmacology*; Proteins/metabolism; Rats; Rats, Inbred Strains; Subcellular Fractions/enzymology; Succinate Dehydrogenase/metabolism

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