EurekaMag
+ Most Popular
Cunninghamia lanceolata plantations in China
Mammalian lairs in paleo ecological studies and palynology
Studies on technological possibilities in utilization of anhydrous milk fat for production of recombined butter-like products
Should right-sided fibroelastomas be operated upon?
Large esophageal lipoma
Apoptosis in the mammalian thymus during normal histogenesis and under various in vitro and in vivo experimental conditions
Poissons characoides nouveaux ou non signales de l'Ilha do Bananal, Bresil
Desensitizing efficacy of Colgate Sensitive Maximum Strength and Fresh Mint Sensodyne dentifrices
Administration of fluid by subcutaneous infusion: revival of a forgotten method
Tundra mosquito control - an impossible dream?
Schizophrenia for primary care providers: how to contribute to the care of a vulnerable patient population
Geochemical pattern analysis; method of describing the Southeastern limestone regional aquifer system
Incidence of low birth weights in a hospital of Mexico City
Tabanidae
Graded management intensity of grassland systems for enhancing floristic diversity
Microbiology and biochemistry of cheese and fermented milk
The ember tetra: a new pygmy characid tetra from the Rio das Mortes, Brazil, Hyphessobrycon amandae sp. n. (Pisces, Characoidei)
Risk factors of contrast-induced nephropathy in patients after coronary artery intervention
Renovation of onsite domestic wastewater in a poorly drained soil
Observations of the propagation velocity and formation mechanism of burst fractures caused by gunshot
Systolic blood pressure in a population of infants in the first year of life: the Brompton study
Haematological studies in rats fed with metanil yellow
Studies on pasteurellosis. I. A new species of Pasteurella encountered in chronic fowl cholera
Dormancy breaking and germination of Acacia salicina Lindl. seeds
therapy of lupus nephritis. a two-year prospective study

Bile acids exert negative feedback control on bile acid synthesis in cultured pig hepatocytes by suppression of cholesterol 7 alpha-hydroxylase activity


Bile acids exert negative feedback control on bile acid synthesis in cultured pig hepatocytes by suppression of cholesterol 7 alpha-hydroxylase activity



Hepatology 12(5): 1209-1215



ISSN/ISBN: 0270-9139

PMID: 2227820

DOI: 10.1002/hep.1840120522

Feedback regulation of bile acid synthesis by its end products was studied in cultured hepatocytes of young weaned pigs. We previously showed that conversion of exogenous [14C] cholesterol into bile acids was suppressed by addition of bile acids to the culture medium. In the present study, the effects of bile acids on bile acid mass production and cholesterol 7 alpha-hydroxylase activity were examined. Mass production of bile acids was strongly inhibited by addition of taurocholic acid (50 and 100 mumol/L) to the culture medium. The inhibitory action was exerted specifically on activity of cholesterol 7 alpha-hydroxylase because conversion of [14C] 7 alpha-hydroxycholesterol to bile acids by pig hepatocytes was not affected. Suppression of cholesterol 7 alpha-hydroxylase activity after incubation of the hepatocytes with taurocholic acid was concentration- and time-dependent. Maximum suppression (-80%) was achieved after a 20 to 30 hr incubation of hepatocytes with 100 mumol/L of this bile acid. Decline of enzyme activity caused by 100 mumol/L taurocholic acid followed first-order kinetics with a half-life of 10 hr. Taurocholic acid had no direct effect on cholesterol 7 alpha-hydroxylase activity in homogenates of hepatocytes as assessed by addition of the bile acid to the assay mixture. The effects of several other bile acids in a concentration of 100 mumol/L on cholesterol 7 alpha-hydroxylase activity were examined in 48 hr incubations. Glycochenodeoxycholic and glycohyodeoxycholic acids, which are the major bile acids in pig bile, their unconjugated forms and also deoxycholic and cholic acid pronouncedly inhibited activity of the enzyme.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 039386374

Download citation: RISBibTeXText

Related references

Feedback regulation of bile acid synthesis in cultured pig hepatocytes by inhibition of cholesterol 7 alpha hydroxylase activity. Hepatology 8(5): 1358, 1988

Maintenance of bile acid synthesis and cholesterol 7 alpha-hydroxylase activity in cultured rat hepatocytes. Biochemical Journal 272(1): 273-275, 1990

Insulin suppresses bile acid synthesis and cholesterol 7 alpha hydroxylase activity in cultured rat hepatocytes. Hepatology 12(4 Part 2): 892, 1990

Importance of culture conditions for maintenance of cholesterol 7 alpha hydroxylase activity and bile acid synthesis in cultured rat hepatocytes. Hepatology 10(4): 732, 1989

The negative effects of bile acids and tumor necrosis factor-alpha on the transcription of cholesterol 7alpha-hydroxylase gene (CYP7A1) converge to hepatic nuclear factor-4: a novel mechanism of feedback regulation of bile acid synthesis mediated by nuclear receptors. Journal of Biological Chemistry 276(33): 30708-30716, 2001

Regulation of bile acid synthesis in the rat: relationship between hepatic cholesterol 7 alpha-hydroxylase activity and portal bile acids. Journal of Lipid Research 36(2): 315-321, 1995

Insulin suppresses bile acid synthesis in cultured rat hepatocytes by down-regulation of cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase gene transcription. Hepatology 21(2): 501-510, 1995

Differential feedback regulation of cholesterol 7 alpha-hydroxylase mRNA and transcriptional activity by rat bile acids in primary monolayer cultures of rat hepatocytes. Biochemical Journal 290: 685-691, 1993

Bile acid sulfonate and 7-alkylated bile acid analogs: effect on intestinal absorption of taurocholate and cholesterol 7alpha-hydroxylase activity in cultured rat hepatocytes. Steroids 65(1): 24-28, 2000

The negative effects of bile acids and tumor necrosis factor-a on the transcription of cholesterol 7a-hydroxylase gene (CYP7A1) converge to hepatic nuclear factor-4. A novel mechanism of feedback regulation of bile acid synthesis mediated by nuclear receptors. The Journal of Biological Chemistry 276(33): 708-16, 2001

Lipoprotein cholesterol uptake mediates up-regulation of bile-acid synthesis by increasing cholesterol 7α-hydroxylase but not sterol 27-hydroxylase gene expression in cultured rat hepatocytes. Biochemical Journal 341(2): 339-346, 1999

Lipoprotein cholesterol uptake mediates up-regulation of bile-acid synthesis by increasing cholesterol 7alpha-hydroxylase but not sterol 27-hydroxylase gene expression in cultured rat hepatocytes. Biochemical Journal 341: 339-346, 1999

Cholesterol 7 alpha-hydroxylase activity and bile acid synthesis in hepatocytes of unweaned and weaned pigs in monolayer culture. Biochimica et Biophysica Acta 1042(3): 386-394, 1990

Cafestol, the cholesterol-raising factor in boiled coffee, suppresses bile acid synthesis by downregulation of cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase in rat hepatocytes. Arteriosclerosis Thrombosis and Vascular Biology 17(11): 3064-3070, 1997

Suppression of sterol 27-hydroxylase mRNA and transcriptional activity by bile acids in cultured rat hepatocytes. Biochemical Journal 305: 505-511, 1995