Diet-induced hypercholesterolemia alters liver glycosaminoglycans and associated-lipoprotein receptors in rats

ABSTRACT

Glycosaminoglycans (GAGs) play an important role in lipoprotein metabolism. In liver, it facilitates the uptake of remnants through receptor-independent endocytosis. However, changes in liver GAGs during diet-induced hypercholesterolemia with normal levels of fat feeding are unknown. Present paper highlights the effect of diet-induced hypercholesterolemia with normal levels (5%) of fat on liver GAGs and other associated lipoprotein receptors. Hypercholesterolemia was induced in rats by feeding diet supplemented with 0.5% cholesterol and 0.125% bile salts. Hypercholesterolemia showed significantly decreased GAGs of both heparan sulfate (HS) and chondroitin sulfate/dermatan sulfate (CS/DS) classes of molecules. Quantitative real-time polymerase chain reaction analysis of GAG biosynthetic enzymes and other genes revealed significant changes in expression profile. The decrease in GAGs was prevented by simvastatin treatment; a drug that inhibits endogenous cholesterol synthesis that was used as a positive control in our study. Furthermore, there was a comparatively decreased binding of GAGs from hypercholesterolemic rats to lipoprotein lipase. LRP1 which plays a major role in lipoprotein uptake was also significantly decreased, and it was attenuated in simvastatin-treated hypercholesterolemic rats. Furthermore, LDLR and ApoE were also decreased significantly in liver of hypercholesterolemic rats. Thus, diet-induced hypercholesterolemia results in dysregulation of cholesterol homeostasis apparently through changes in GAGs in conjunction with other associated players