FAILURE OF INTRAVENOUS-INFUSION OF TAUROCHOLATE TO DOWN-REGULATE CHOLESTEROL 7-ALPHA-HYDROXYLASE IN RATS WITH BILIARY FISTULAS

Title

FAILURE OF INTRAVENOUS-INFUSION OF TAUROCHOLATE TO DOWN-REGULATE CHOLESTEROL 7-ALPHA-HYDROXYLASE IN RATS WITH BILIARY FISTULAS

Creator

Pandak W M; Heuman D M; Hylemon P B; Chiang J Y L; Vlahcevic Z R

Publisher

Gastroenterology

Date

1995
1995-02

Description

Background/Aims: The decrease in cholesterol 7 alpha-hydroxylase induced by intraduodenal infusion of taurocholate in bile fistula vats may be indirect, i.e., mediated through release or absorption of an intestinal factor in response to the presence of bile salts in the intestine. The aim of this study was to determine if negative feedback regulation of cholesterol 7 alpha-hydroxylase can be shown when equimolar concentrations of taurocholate are administered intravenously, thus bypassing the intestine. Methods: After 96 hours of biliary diversion, taurocholate (36 mu mol.h(-1).100 g rat(-1)) was infused into the rats either intravenously or intraduodenally for the final 24 hours. Livers were then harvested for analysis of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase specific activity, cholesterol 7 alpha-hydroxylase specific activity, messenger RNA levels, and transcriptional activity. Results: Intra-duodenally administered taurocholate significantly decreased HMG-CoA reductase and cholesterol 7 alpha-hydroxyfase specific activity by more than 50% and cholesterol 7 alpha-hydroxylase steady-state messenger RNA levels and transcriptional activity by 50%-75%. In contrast, intravenous administration of taurocholate failed to down-regulate either cholesterol 7 alpha-hydroxylase or HMG-CoA reductase. Conclusions: Passage of taurocholate through the intestine strongly potentiates negative feedback regulation of cholesterol 7 alpha-hydroxylase. A putative intestinal factor, released or absorbed in the presence of bile acids in the intestinal lumen, may play a role in the regulation of bile acid synthesis.

Subject

3-hydroxy-3-methylglutaryl; bile-acid synthesis; cholesterol; coenzyme; coenzyme-a reductase; feedback-regulation; Gastroenterology & Hepatology; hepatic; hepatocytes; liquid-chromatography; liver; messenger-rna levels; performance; transcriptional regulation

Format

Journal Article

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Rights

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Pages

533-544

Issue

2

Volume

108

Citation

Pandak W M; Heuman D M; Hylemon P B; Chiang J Y L; Vlahcevic Z R, “FAILURE OF INTRAVENOUS-INFUSION OF TAUROCHOLATE TO DOWN-REGULATE CHOLESTEROL 7-ALPHA-HYDROXYLASE IN RATS WITH BILIARY FISTULAS,” NEOMED Bibliography Database, accessed October 21, 2021, https://neomed.omeka.net/items/show/6708.

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