ABSTRACT
Drinking water can be contaminated with pharmaceuticals. However, it is uncertain whether this contamination can be harmful for the liver, especially during obesity. Hence, the goal of our study was to determine whether chronic exposure to low doses of pharmaceuticals could have deleterious effects on livers of lean and obese mice. To this end, lean and ob/ob male mice were treated for 4 months with a mixture of 11 drugs provided in drinking water at concentrations ranging from 10 to 106 ng/l. At the end of the treatment, some liver and plasma abnormalities were observed in ob/ob mice treated with the cocktail containing 106 ng/l of each drug. For this dosage, a gene expression analysis by microarray showed altered expression of circadian genes (e.g. Bmal1, Dbp, Cry1) in lean and obese mice. RT-qPCR analyses carried out in all groups of animals confirmed that expression of 8 different circadian genes was modified in a dose-dependent manner. For some genes, a significant modification was observed for dosages as low as 10²-10³ ng/l. Drug mixture and obesity presented an additive effect on circadian gene expression. These data were validated in an independent study performed in female mice. Thus, our study showed that chronic exposure to trace pharmaceuticals disturbed hepatic expression of circadian genes, particularly in obese mice. Because some of the 11 drugs can be found in drinking water at such concentrations (e.g. acetaminophen, carbamazepine, ibuprofen) our data could be relevant in environmental toxicology, especially for obese individuals exposed to these contaminants.
Subject(s)
Drug-Related Side Effects and Adverse Reactions , Gene Expression Regulation/drug effects , Liver/drug effects , Obesity/metabolism , Period Circadian Proteins/metabolism , Pharmaceutical Preparations/administration & dosage , Water Pollutants, Chemical/administration & dosage , ARNTL Transcription Factors/agonists , ARNTL Transcription Factors/antagonists & inhibitors , ARNTL Transcription Factors/genetics , ARNTL Transcription Factors/metabolism , Animals , Cryptochromes/agonists , Cryptochromes/antagonists & inhibitors , Cryptochromes/genetics , Cryptochromes/metabolism , DNA-Binding Proteins/agonists , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Dose-Response Relationship, Drug , Female , Gene Expression Profiling , Liver/metabolism , Liver/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Obese , Obesity/chemically induced , Obesity/pathology , Oligonucleotide Array Sequence Analysis , Period Circadian Proteins/agonists , Period Circadian Proteins/antagonists & inhibitors , Period Circadian Proteins/genetics , Toxicity Tests, Chronic , Transcription Factors/agonists , Transcription Factors/antagonists & inhibitors , Transcription Factors/genetics , Transcription Factors/metabolism , Water Pollutants, Chemical/toxicityABSTRACT
Impairment of the circadian clock has been associated with numerous disorders, including metabolic disease. Although small molecules that modulate clock function might offer therapeutic approaches to such diseases, only a few compounds have been identified that selectively target core clock proteins. From an unbiased cell-based circadian phenotypic screen, we identified KL001, a small molecule that specifically interacts with cryptochrome (CRY). KL001 prevented ubiquitin-dependent degradation of CRY, resulting in lengthening of the circadian period. In combination with mathematical modeling, our studies using KL001 revealed that CRY1 and CRY2 share a similar functional role in the period regulation. Furthermore, KL001-mediated CRY stabilization inhibited glucagon-induced gluconeogenesis in primary hepatocytes. KL001 thus provides a tool to study the regulation of CRY-dependent physiology and aid development of clock-based therapeutics of diabetes.
