Chronic Contamination with137Cesium in Rat: Effect on Liver Cholesterol Metabolism

Abstract

After the Chernobyl nuclear accident, epidemiological studies on human populations living in137Cs-contaminated areas revealed the increase frequencies of thyroid cancer and evoked the apparition of cardiovascular diseases, hormonal effect, liver alteration, and lipid disorder. Actually, it raises a problem of public safety for the populations living on these territories that are exposed to low levels of137Cs during a long period through food. Then it is necessary to study potential effect of this chronic contamination. To mimic this situation, the authors investigate the potential biological effects of chronic exposure to137Cs at a postaccidental dose (150 Bq/rat/day) on hepatic metabolism of cholesterol in rat. Plasma lipid level, gene expression and activity were analyzed. It was observed that in137Cs-exposed rats, gene expression of low-density lipoprotein receptor (LDLr), apolipoprotein B (apoB), and liver X receptor α (LXR α) are increased (95%, p < .05; 34%, p < .05; 20%, p < 0.05, respectively), whereas transporter adenosine triphosphate–binding cassette transporter G5 (ABCG5) is decreased (42%, p < .05). In addition, cytochrome P450 27A1 (CYP27A1) activity is increased (34%, p < .05) in contaminated rat liver. In conclusion, the results suggest that137Cs contamination at low-level induces molecular modifications of the liver cholesterol metabolism without leading to a dysregulation of its homeostasis. These results suggest that chronic long term exposure at low-level of137Cs may evolve to lipid disorder.