The effect of silymarin on expression of selected ABC transporters in the rat.

Silymarin (standardized extract from the seeds of the Silybum marianum) has been used in the sup- portive therapy of liver diseases and its cytoprotective activity is believed to be based on antioxidant properties. Our previous works showed hypolipidemic effects of silymarin. The ATP-binding cassette (ABC) transporters G5 and G8 play a major role in biliary cholesterol secretion. The ABCA1 transporter plays a significant role in move- ment of cellular cholesterol to high density lipoproteins. We investigated the possibility that silymarin affects the regulation of lipid metabolism via selected ABC transporters using rats fed a high-cholesterol diet with silymarin. The major finding in this study is that silymarin up-regulated mRNA of ABC transporters (G5, G8 and A1). This result suggests that silymarin positively affects the plasma lipoprotein profile via up-regulation of ABC transport - ers involved in lipid metabolism. Furthermore, this study shows for the first time that silymarin up-regulates the expression of these ABC transporters at the mRNA level.