RESUMO
OBJECTIVE: Cholestyramine (CHO), as a bile acid sequestering exchange resin, has been widely used to treat hypercholesterolemia. The aim of this study was to explore how CHO regulated serum cholesterol amounts and bile acid levels in animal models. METHODS: New Zealand White rabbits were randomly assigned to the control (given distilled water) and CHO-treated (given CHO solution 1 g/kg per day for 2 weeks) groups. To assess bile acid pool size, bile fistulas were constructed in five rabbits in each group. Serum cholesterol levels and biliary and fecal bile outputs were determined. Liver cholesterol 7α-hydroxylase ( CYP7A1 ), small heterodimer partner ( SHP ), bile salt export pump ( BSEP ), ileal bile acid-binding protein ( IBABP ) and LDL receptor ( LDL-R ) mRNA expressions were assessed by real-time polymerase chain reaction. CYP7A1 activity was also determined. RESULTS: CHO treatment decreased serum cholesterol levels by 12.1%. Although CHO did not change the bile acid pool size and biliary bile acid output, it significantly increased fecal bile acid output. Interestingly, CHO also significantly increased the expression and activity of CYP7A1, as well as IBABP and LDL-R mRNA expressions, but decreased hepatic SHP and BSEP gene expressions. CONCLUSION: CHO markedly alters bile acid and cholesterol amounts in rabbit intestinal and liver tissues, downregulating genes responsible for cholesterol homeostasis.
Assuntos
Resinas de Troca Aniônica/farmacologia , Ácidos e Sais Biliares/metabolismo , Colesterol 7-alfa-Hidroxilase/metabolismo , Colesterol/sangue , Resina de Colestiramina/farmacologia , Expressão Gênica/efeitos dos fármacos , RNA Mensageiro/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Ácidos e Sais Biliares/análise , Colesterol 7-alfa-Hidroxilase/genética , Proteínas de Ligação a Ácido Graxo/genética , Fezes/química , Mucosa Intestinal/metabolismo , Fígado/metabolismo , Masculino , Coelhos , Distribuição Aleatória , Receptores Citoplasmáticos e Nucleares/genética , Receptores de LDL/genéticaRESUMO
OBJECTIVE: To investigate the effects of Fufang Jiangzhi No. 3, a compound traditional Chinese herbal medicine, on cholesterol-bile acid metabolism in rabbits with hypercholesterolemia and to explore the mechanism. METHODS: Twenty-four male New Zealand white rabbits were randomly assigned into normal control group, untreated group and Fufang Jiangzhi No. 3 group, with 8 rabbits in each group. Rabbits in the untreated group and Fufang Jiangzhi No. 3 group were fed high cholesterol diet to induce hypercholesterolemia. After 4-week treatment, serum total cholesterol and bile acid contents were assessed. Activity of cholesterol 7alpha-hydroxylase (CYP7A1) in liver tissues was measured by enzyme-linked immunosorbent assay. The expressions of CYP7A1, bile salt export pump (BSEP) and small heterodimer partner (SHP) mRNAs in liver tissues were observed by real-time fluorescent quantitative polymerase chain reaction. RESULTS: Compared with the normal control group, serum total cholesterol and bile acid contents in the untreated group were increased (P<0.01). Activity of CYP7A1 and expression of CYP7A1 mRNA were decreased and expressions of BSEP and SHP mRNAs were increased in liver tissues in the untreated group as compared with the normal control group (P<0.01). Serum total cholesterol level, and expressions of BSEP and SHP mRNAs in the Fufang Jiangzhi No. 3 group were lower than those in the untreated group (P<0.01). The CYP7A1 activity and expression of CYP7A1 mRNA in the Fufang Jiangzhi No. 3 group were increased as compared with the untreated group (P<0.01), however, there was no significant difference in bile acid between the Fufang Jiangzhi No. 3 group and the untreated group. CONCLUSION: Fufang Jiangzhi No. 3 can up-regulate the expression of CYP7A1 mRNA, raise the activity of CYP7A1, and inhibit the expressions of BSEP and SHP mRNAs to regulate the metabolism of total cholesterol in rabbits.
