Expressive Modulation of the Cyp7a1 and Ibat Protein by Cholesterol and its Contribution to the Maintenance of the Normal Cholesterolemia in Mouse

The aim of our study is to prove the existence of a very coordinated system of regulation between the route of excretion of taurocholic acid and cholesterol. We proceed to follow up physiologically animals, with no differences in water and food consumptions between the control group and the group of 5% diet of cholesterol. On the other hand dieresis has increased in mice with 5% diet of cholesterol. Cholesterol induced in the liver the transcribed rate of Cholesterol 7α-hydroxylaze (CYP7A1), limiting enzyme of bile acids synthesis. What’s more, expression of CYP7A1 encoding gene is induced in mice with 5% diet of cholesterol. Also we noticed an increase of distribution and wealth expression related to the RNA and CYP7A1 in the liver reported by Northern Blotting. According to ileum role in intestinal re-absorption of bile acids, our interest was focused on the ileac transportation: the standard expression of Ileal Bile Acid Transporter (IBAT) has strongly reduced; in mice with rich diet of cholesterol the Western Blotting of proteins has quantitatively reduced. IBAT’s oppression can be explained by the diminution of the ileac transportation of taurocholic acid (TCA).It results an increase of fecal flight of TCA in mice with a rich diet of cholesterol.