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Amiodarone-induced hypercholesterolemia is associated with a decrease in liver LDL receptor mRNA
F Hudig1, O Bakker, W M Wiersinga
1Department of Endocrinology, University of Amsterdam, The Netherlands.
Abstract:
Amiodarone decreases plasma and tissue triiodothyronine (T3) and increases plasma cholesterol levels resembling changes seen during hypothyroidism. To elucidate the mechanism of amiodarone-induced hypercholesterolemia we investigated gene expression of three key proteins in cholesterol metabolism (cholesterol 7 alpha-hydroxylase, LDL receptor, HMG-CoA reductase) in livers of rats. Animals were treated with amiodarone or propylthiouracil (to induce mild hypothyroidism). The LDL receptor mRNA was downregulated (approximately 50%) in both amiodarone-treated and hypothyroid animals, while the other mRNA remained unchanged after 14-day treatment. The results suggest that amiodarone-induced hypercholesterolemia is associated with decreased LDL receptor mRNA levels.
Insights
Amiodarone increases cholesterol by reducing LDL receptor mRNA in rat livers, similar to hypothyroidism effects. This suggests a key mechanism for amiodarone-induced hypercholesterolemia.
Area of Science:
- Pharmacology
- Molecular Biology
- Endocrinology
Background:
- Amiodarone alters thyroid hormone levels (triiodothyronine) and increases plasma cholesterol.
- These changes mimic those observed in hypothyroidism.
- The precise mechanism of amiodarone-induced hypercholesterolemia requires elucidation.
Purpose of the Study:
- To investigate the mechanism behind amiodarone-induced hypercholesterolemia.
- To examine the gene expression of key cholesterol metabolism proteins in rat livers.
- To compare amiodarone's effects with those of induced hypothyroidism.
Main Methods:
- Rats were treated with amiodarone or propylthiouracil (hypothyroidism model).
- Gene expression of cholesterol 7 alpha-hydroxylase, LDL receptor, and HMG-CoA reductase was analyzed in liver tissue.
- mRNA levels were quantified after 14 days of treatment.
Main Results:
- Amiodarone treatment led to a significant downregulation (approx. 50%) of LDL receptor mRNA.
- Hypothyroid animals (propylthiouracil-treated) also showed decreased LDL receptor mRNA levels.
- Gene expression of cholesterol 7 alpha-hydroxylase and HMG-CoA reductase remained unchanged in both treatment groups.
Conclusions:
- Amiodarone-induced hypercholesterolemia is associated with reduced levels of LDL receptor mRNA in the liver.
- The downregulation of LDL receptors may contribute to elevated plasma cholesterol levels.
- This finding provides insight into the molecular mechanisms linking amiodarone use to lipid profile changes.