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Gene expression profiles of amiodarone, valproic acid, and tetracycline induced steatosis in C57BL/6 mice

ABSTRACT: Toxicogenomics (tgx) is used as a tool to identify mechanisms and markers of steatosis in C57BL/6 mice treated by oral gavage using amiodarone (AMD), valproic acid (VPA), and tetracycline (TET). Critical doses for tgx analysis were derived from a 25 day dose range finding study. For tgx analysis, livers of mice were collected after 1, 4, and 11 days of repeated treatment with 6.7, 20, and 60 mg/kg bw for AMD; 125, 250, and 500 mg/kg bw for VPA; and 14.8, 44, and 133 mg/kg bw for TET.

ORGANISM(S): Mus musculus

PROVIDER: GSE48126 | GEO | 2014/02/25

SECONDARY ACCESSION(S): PRJNA209053

REPOSITORIES: GEO

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Project description:Amiodarone reversibly decreases sodium-iodide symporter mRNA expression at therapeutic concentrations and induces antioxidant responses at supraphysiological concentrations in cultured human thyroid follicles Amiodarone, a potent antiarrhythmic agent, is a highly active oxidant, exerting cytotoxic effects on thyrocytes at pharmacological concentrations. Patients receiving amiodarone usually remain euthyroid, but occasionally develop thyroid dysfunction, such as amiodarone-associated hypothyroidism or amiodarone-induced thyrotoxicosis. To elucidate the mechanism by which amiodarone elicits thyroid dysfunction, human thyroid follicles were cultured with TSH and amiodarone at therapeutic (1-2 microM) and pharmacological (10-20microM) concentrations, and the drug-induced effect on whole human gene expression was analyzed by cDNA microarray. Amiodarone at 1-2microM decreased the expression level of the sodium-iodide symporter (NIS) to nearly half, but did not affect genes participating in thyroid hormonogenesis (thyroid peroxidase, thyroglobulin, pendrin, NADPH oxidase). Higher concentrations (10-20 microM) decreased the expression of all these genes, accompanied by increased expression of antioxidant proteins such as heme oxygenase 1 and ferritin. When thyroid follicles obtained from a patient with Graves’ disease who had been treated with amiodarone for 2 months before thyroidectomy were cultured in amiodarone-free medium, TSH-induced thyroid function was intact, suggesting that amiodarone at a maintenance dose did not elicit any cytotoxic effect on thyrocytes. The ultrastructural features of cultured thyroid follicles were compatible with these in vitro findings. These in vitro and ex vivo findings suggest that patients taking maintenance doses of amiodarone usually remain euthyroid, probably due to escape from the Wolff-Chaikoff effect mediated by decreased expression of NIS mRNA. Furthermore, amiodarone is not cytotoxic for thyrocytes at therapeutic concentrations but elicits cytotoxicity through oxidant activity at supra-physiological concentrations. Keywords: Cultured human thyroid follicles

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Gene expression profiles of amiodarone, valproic acid, and tetracycline induced steatosis in C57BL/6 mice

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