Dr. Villagran-Orellana, Marcelo

Background: It is known that some nutrients play an important role in the development of cholelithiasis. Cholesterol is carried by micelles and vesicles in the bile. During the first stage of gallstone formation, cholesterol crystals derive from thermodynamically unstable vesicles. Aim: To determine the effect of a high fat diet on blood lipids and bile composition, and its implication in the formation of gallstones. Material and Methods: Two groups of 15 BALB/c mice each, coming from the same litter, were treated with a control or with a high-fat diet (64% fat and 0.14% cholesterol). After two months, the animals were sacrificed, blood and bile samples were obtained. Serum glucose and the corresponding lipid profiles were measured. In bile samples, cholesterol and phospholipid levels were analyzed, and cholesterol transporters (vesicles and micelles) were separated by gel filtration chromatography. Results: Treated animals showed an 87% increase in serum total cholesterol (p < 0.01), a 97% increase in HDL-cholesterol (p < 0.05) and a 140% increase in LDL-cholesterol (p < 0.05). No changes in serum triglycerides or glucose were observed. In bile, a 13% increase in biliary cholesterol (p < 0.05) was observed but no change in biliary phospholipids. Also, an increase in biliary vesicular transporters and an increase of cholesterol/phospholipid ratio in vesicular transporters were observed. Conclusions: A high fat diet may contribute to the formation of gallstones in our experimental model.