ArticlePDF Available

Metabolism of lithocholic acid in the rat: formation of lithocholic acid 3-O-glucuronide in vivo

May 1990
Journal of Lipid Research 31(4):615-22

May 1990
31(4):615-22

DOI:10.1016/S0022-2275(20)42829-9

Source
PubMed

License
CC BY 4.0

Authors:

Karen E Shattuck

University of Texas Medical Branch at Galveston

Rhanee Lester

University of Adelaide

Show all 5 authorsHide

Milligram amounts of [3 beta-3H]lithocholic (3 alpha-hydroxy-5 beta-cholanoic) acid were administered by intravenous infusion to rats prepared with a biliary fistula. Analysis of sequential bile samples by thin-layer chromatography (TLC) demonstrated that lithocholic acid glucuronide was present in bile throughout the course of the experiments and that its secretion rate paralleled that of total isotope secretion. Initial confirmation of the identity of this metabolite was obtained by the recovery of labeled lithocholic acid after beta-glucuronidase hydrolysis of bile samples. For detailed analysis of biliary metabolites of [3H]lithocholic acid, pooled bile samples from infused rats were subjected to reversed-phase chromatography and four major labeled peaks were isolated. After complete deconjugation, the two major compounds in the combined first two peaks were identified as murideoxycholic (3 alpha, 6 beta-dihydroxy-5 beta-cholanoic) and beta-muricholic (3 alpha, 6 beta, 7 beta-trihydroxy-5 beta-cholanoic) acids and the third peak was identified as taurolithocholic acid. The major component of the fourth peak, after isolation, derivatization (to the methyl ester acetate), and purification by high pressure liquid chromatography (HPLC), was positively identified by proton nuclear magnetic resonance as lithocholic acid 3 alpha-O-(beta-D-glucuronide). These studies have shown, for the first time, that lithocholic acid glucuronide is a product of in vivo hepatic metabolism of lithocholic acid in the rat.

Content uploaded by Karen E Shattuck

Content may be subject to copyright.

Available via license: CC BY 4.0

Content may be subject to copyright.

A preview of the PDF is not available

Rumen microbiome-driven insight into bile acid metabolism and host metabolic regulation

Article

Jun 2024
ISME J

Gut microbes play a crucial role in transforming primary bile acids (BAs) into secondary forms, which influence systemic metabolic processes. The rumen, a distinctive and critical microbial habitat in ruminants, boasts a diverse array of microbial species with multifaceted metabolic capabilities. There remains a gap in our understanding of BA metabolism within this ecosystem. Herein, through the analysis of 9371 metagenome-assembled genomes and 329 cultured organisms from the rumen, we identified two enzymes integral to BA metabolism: 3-dehydro-bile acid delta4,6-reductase (baiN) and the bile acid:Na + symporter family (BASS). Both in vitro and in vivo experiments were employed by introducing exogenous BAs. We revealed a transformation of BAs in rumen and found an enzyme cluster, including L-ribulose-5-phosphate 3-epimerase and dihydroorotate dehydrogenase. This cluster, distinct from the previously known BA-inducible operon responsible for 7α-dehydroxylation, suggests a previously unrecognized pathway potentially converting primary BAs into secondary BAs. Moreover, our in vivo experiments indicated that microbial BA administration in the rumen can modulate amino acid and lipid metabolism, with systemic impacts underscored by core secondary BAs and their metabolites. Our study provides insights into the rumen microbiome’s role in BA metabolism, revealing a complex microbial pathway for BA biotransformation and its subsequent effect on host metabolic pathways, including those for glucose, amino acids, and lipids. This research not only advances our understanding of microbial BA metabolism but also underscores its wider implications for metabolic regulation, offering opportunities for improving animal and potentially human health.

Lithocholic Acid

Chapter

Oct 2014

Lin Xu

This article has no abstract.

Design, Synthesis, In Vitro Characterization and Preliminary Imaging Studies on Fluorinated Bile Acid Derivatives as PET Tracers to Study Hepatic Transporters

Article

Dec 2016

With the aim of identifying a fluorinated bile acid derivative that could be used as [¹⁸F]-labeled Positron Emission Tomography (PET) tracer for imaging the in vivo functioning of liver transporter proteins, and particularly of OATP1B1, three fluorinated bile acid triazole derivatives of cholic, deoxycholic and lithocholic acid (CATD, DCATD and LCATD 4a-c, respectively) were synthesized and labeled with tritium. In vitro transport properties were studied with cell-based assays to identify the best substrate for OATP1B1. In addition, the lead compound, LCATD (4c), was tested as a substrate of other liver uptake transporters OATP1B3, NTCP and efflux transporter BSEP to evaluate its specificity of liver transport. The results suggest that 4c is a good substrate of OATP1B1 and NTCP, whereas it is a poor substrate of OATP1B3. The efflux transporter BSEP also appears to be involved in the excretion of 4c from hepatocytes. The automated radiosynthesis of [¹⁸F]-4c was accomplished in a multi-GBq scale and a pilot imaging experiment in a wild type rat was performed after i.v. administration to assess the biodistribution and clearance of the tracer. PET imaging revealed that radioactivity was primarily located in the liver (tmax = 75 seconds) and cleared exclusively through the bile, thus allowing to image the hepatobiliary excretion of bile acids in the animal model. These findings suggest that [¹⁸F]-LCATD 4c is a promising PET probe for the evaluation of hepatic transporters OATP1B1, NTCP and BSEP activity with potential for studying drug-drug interactions and drug-induced toxicity involving these transporters.

Application of 5-azido-UDP-glucose and 5-azido-UDP-glucuronic acid photoaffinity probes for the determination of the active site orientation of microsomal UDP-glucosyltransferases and UDP-glucuronosyltransferases.

Article

Full-text available

Jun 1992

A new approach to determining the active site orientation of microsomal glycosyltransferases is presented which utilizes the photoaffinity analogs [P-32]5-Azido-UDP-glucose ([P-32]5N3UDP-Glc) and [P-32]5-Azido-UDP-glucuronic acid ([P-32]5N3UDP-GlcA). It was previously shown that both photoprobes could be used to photolabel UDP-glucose:dolichol phosphate glucosyltransferase (Glc-P-Dol synthase), as well as the family of UDP-glucuronosyltransferases in rat liver microsomes. The effects of detergents, proteases, and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) on the photolabeling of these enzymes were examined in intact rat liver microsomes. Photolabeling of Glc-P-Dol synthase by either photoprobe was the same in intact or disrupted vesicles, was susceptible to trypsin digestion, and was inhibited by the nonpenetrating inhibitor DIDS. Photolabeling of the UDP-glucuronosyltransferases by [P-32]5N3UDP-GlcA was stimulated 1.3-fold in disrupted vesicles as compared to intact vesicles, whereas photolabeling of these enzymes by [P-32]5N3UDP-Glc showed a 14-fold increase when vesicles were disrupted. Photolabeled UDP-glucuronosyltransferases were only susceptible to trypsin digestion in disrupted vesicles, and this was further verified by Western blot analyses. The results indicate a cytoplasmic orientation for access of UDP-sugars to Glc-P-Dol synthase and a lumenal orientation of most UDP-glucuronosyltransferases.

Liver Cytochrome P450 Metabolism of Endogenous Steroid Hormones, Bile Acids, and Fatty Acids

Chapter

Jan 1993

Cytochromes P450 metabolize a large variety of lipophilic compounds that often have little or no structural similarity. Common cytochrome P450 substrates include both xenobiotics (drugs, carcinogens, environmental pollutants, and other chemicals) and endogenous metabolites (steroids, fatty acids, prostaglandins, etc.). As shown in Fig. 1, the major sites of cytochrome P450 action in mammalian metabolism are reactions connected to sterol metabolism. Notable exceptions include the ω and ω-1 oxidation of fatty acids (catalyzed by cytochrome P450 family 4) and the oxidation of ethanol and other low molecular weight compounds (cytochrome P450 subfamily 2E). Both the biosynthesis of cholesterol (lanosterol demethylase) and the conversion of cholesterol into its metabolites require the participation of multiple cytochromes P450, each of which catalyzes a distinct hydroxylation reaction, some of which lead to carbon-carbon cleavage (desmolase activity; e.g., cytochrome P450 11 A). Quantitatively most important for cholesterol catabolism is the pathway leading to bile acids, which involves several distinct cytochrome P450 enzymes, including cholesterol 7α-hydroxylase (cytochrome P450 family 7), which catalyzes the first, and rate-limiting, step; a 27-hydroxylation (cytochrome P450 family 27) that initiates side chain oxidation, and a 12α-hydroxylation that leads to cholic acid formation.

Hepatic metabolism of short-chain bile acids. Inversion of the 3-hydroxyl group of isoetianic acid (3P-hyd roxy5P-and rostane-1 ?@car boxyl ic acid) by the adult rat

Article

Full-text available

The stereospecificity of mechanisms for hepatic trans- port of short-chain bile acids has been examined by following the hepatic metabolism and biliary secretion of 30-hydroxy-50- androstane-l7~-carboxylic acid (isoetianic acid) administered in two different labeled forms to rats prepared with an external biliary fistula. While 93 76 of the administered (2,2,4,4-3H)iso- etianic acid was recovered in bile after 20 h, only 18% of a similar dose of (3a-3H)isoetianic acid was secreted in bile over the same time period. The recovered radioactivity of the latter compound was mainly associated with bile water. With the (2,2,4,4-JH)iso- etianic acid, the bulk of the biliary isotope was determined to be in the form of two glucuronide conjugates. Spectral analysis identified these metabolites as the hydroxyl-linked (major) and carboxyl-linked (minor) 0-glucuronides, not of the 36-hydroxy compound administered, but of 3a-hydroxy-50-androstane-170-

Bile acid and sterol solubilization in 2-hydroxypropyl-β-cyclodextrin

Article

Full-text available

Apr 1992

The use of 2-hydroxypropyl-beta-cyclodextrin has made it possible to prepare stable aqueous solutions of cholesterol, 26-hydroxycholesterol, 7 alpha-hydroxycholesterol, and monohydroxy bile acids such as lithocholic and 3 beta-hydroxy-5-cholenoic acids. These solutions are suitable for cell culture studies and for parenteral administration to animals.

Pathogenesis of lithocholate-induced intrahepatic cholestasis: Role of glucuronidation and hydroxylation of lithocholate

Article

Jul 1992
Biochim Biophys Acta

It has been shown that lithocholic glucuronide is more cholestatic than lithocholic acid (LCA), as well as its taurine and glycine conjugates. Furthermore, LCA hydroxylation is thought to be a major detoxifying mechanism. Therefore, the role of LCA glucuronidation and hydroxylation was investigated during the development of LCA-induced cholestasis and recovery from it. Male rats received a bolus intravenous injection of [14C]LCA (12 mumol/100 g body weight) and bile samples were collected every 30 min for 5 h. Bile flow (BF) was reduced immediately after LCA injection, dropping to 40% of basal BF at 60 min. It then started to increase, reaching normal bile flow values at 3.5 h. Morphologically, canalicular lesions were dominant at 60 min and virtually absent at 2 h. At 60 min (maximal cholestasis), 30% of the LCA injected was secreted in bile, 20% was found in plasma while the other 50% was recovered in the liver and distributed mainly in plasma membranes, microsomes and cytosol. At the end of the experiment (normal BF), 20% of the LCA injected was still in the liver but was present mainly in the cytosol. In bile, within 30 min after injection, 46% of the LCA secreted was lithocholic glucuronide, 24% was conjugated with taurine and glycine, and 21% was in the form of hydroxylated bile acids. During the recovery period, lithocholic glucuronide secretion decreased to 18-25%. Taurine and glycine conjugate secretion increased to a maximum of 43% at 60 min, after which it was reduced to 21-28%. In contrast, hydroxylated metabolites were elevated during the recovery periods, reaching a maximum (45%) at 120 min and remaining constant thereafter. These results suggest that: (i) LCA binding to plasma membranes and microsomes appeared to correlate with the development of cholestasis; (ii) LCA glucuronidation may initiate and/or contribute to LCA-induced cholestasis; and (iii) hydroxylation predominates during recovery from cholestasis.

Hepatic metabolism of short-chain bile acids. Inversion of the 3-hydroxyl group of isoetianic acid (3 beta-hydroxy-5 beta-androstane-17 beta-carboxylic acid) by the adult rat

Article

Full-text available

Jan 1992

The stereospecificity of mechanisms for hepatic transport of short-chain bile acids has been examined by following the hepatic metabolism and biliary secretion of 3 beta-hydroxy-5 beta-androstane-17 beta-carboxylic acid (isoetianic acid) administered in two different labeled forms to rats prepared with an external biliary fistula. While 93% of the administered [2,2,4,4-3H]isoetianic acid was recovered in bile after 20 h, only 18% of a similar dose of [3 alpha-3H]isoetianic acid was secreted in bile over the same time period. The recovered radioactivity of the latter compound was mainly associated with bile water. With the [2,2,4,4-3H]isoetianic acid, the bulk of the biliary isotope was determined to be in the form of two glucuronide conjugates. Spectral analysis identified these metabolites as the hydroxyl-linked (major) and carboxyl-linked (minor) beta-glucuronides, not of the 3 beta-hydroxy compound administered, but of 3 alpha-hydroxy-5 beta-androstane-17 beta-carboxylic acid (etianic acid), i.e., the products of hydroxyl group inversion. It is concluded that isoetianic acid is efficiently cleared from plasma and conjugated with glucuronic acid after its epimerization to etianic acid. The prevalent, but not complete, loss of the 3-tritium atom and the retention of the 2- and 4-tritium atoms probably indicates a 3-oxo-5 beta-androstane-17 beta-carboxylic acid intermediate with partial return of the label via a limited labeled pool of reduced nicotinamide cofactor.

Biliary excretion of bile acid conjugates in a hyperbihrubinemic mutant Sprague-Dawley rat

Article

Sep 1991

The hepatic transport of bile acid conjugates was studied in the Eisai hyperbilirubinuria rat, a Sprague-Dawley mutant rat with conjugated hyperbilirubinemia. Serum bile acid levels were increased, bile acid-independent bile flow was decreased and biliary glutathione concentrations were markedly decreased in the Eisai hyperbilirubinuria rat. Biliary excretion of sulfobromophthalein was markedly impaired and almost no glutathione conjugate was excreted in the bile of the Eisai hyperbilirubinuria rat. Biliary excretion of lithocholate-3-O-glucuronide and lithocholate-3-sulfate in the Eisai hyperbilirubinuria rat was markedly delayed, whereas that of lithocholate was only slightly delayed. After [14C]chenodeoxycholate infusion (1 mumol/min/100 gm for 60 min), the increases in bile flow and biliary excretion of isotope in the Eisai hyperbilirubinuria rat were not so prominent as those observed in control rats, and the glucuronide of chenodeoxycholate, which constituted about 15% of biliary chenodeoxycholate in control rats, was not observed in the Eisai hyperbilirubinuria rat. Initial uptake of lithocholate and its glucuronide and sulfate by isolated hepatocytes was not impaired in the Eisai hyperbilirubinuria rat; the profiles of cytosolic bile acid binding proteins in Eisai hyperbilirubinuria rat liver were identical to those in control liver. These data indicate that the Eisai hyperbilirubinuria rat has excretory impairment of organic anions, bile acid glucuronide and sulfate and that it has characteristics very similar to those of the hyperbilirubinemic mutant Wistar rats TR- and GY.

Analysis of 3-sulfated and nonsulfated bile acids by one-step solvolysis and high performance liquid chromatography

Article

Full-text available

Dec 1987

A facile solvolysis procedure of 3-sulfated bile acid was devised using trifluoroacetic acid, tetrahydrofuran, and methanol. The sulfate esters were completely solvolyzed within only 2 hr by the present method. The clinical utility of the solvolysis procedure and high performance liquid chromatography using immobilized 3α-hydroxysteroid dehydrogenase was demonstrated in the analysis of the bile acids in serum of patients with obstructive jaundice. The quantities of 3-sulfated bile acids were calculated from the difference in the amount of bile acids before and after solvolysis. A significantly large proportion of 3-sulfated glycochenodeoxycholic acid, i.e., 21.9 to 31.3% of total glycochenodeoxycholic acid, was found in the serum of patients with obstructive jaundice. Thus, the present method permits simultaneous quantitation of 3-sulfated as well as nonsulfated bile acids in biological samples.

Defective biliary secretion of bile acid 3-O-glucuronides in rats with hereditary conjugated hyperbilirubinemia.

Article

Full-text available

Dec 1989

Biliary secretion of bile acid glucuronides was studied in control rats and in rats with a congenital defect in hepatobiliary transport of organic anions (GY rats). In control animals, hepatobiliary transport of [3H]lithocholic acid 3-O-glucuronide and [3H]cholic acid 3-O-glucuronide was efficient (greater than 95% in 1 h) and comparable to that of [14C]taurocholic acid. Secretion of both glucuronides was impaired in GY rats (24% and 71% at 1 h), whereas that of taurocholate was similar to control values. However, recovery of the glucuronides in bile was nearly complete within 24 h; virtually no radioactivity was found in urine. In control rats, biliary secretion of lithocholic acid 3-O-glucuronide, but not that of cholic acid 3-O-glucuronide or taurocholate, could be delayed by simultaneous infusion of dibromosulphthalein. In mutant rats, dibromosulphthalein infusion was also able to inhibit secretion of cholic acid 3-O-glucuronide. [3H]Hydroxyetianic acid, a C20 short-chain bile acid, was secreted by control rats as a mixture of 20% carboxyl-linked and 80% hydroxyl-linked (3-O-)glucuronide; secretion was very efficient (99% in 1 h). In GY rats, secretion was drastically impaired (16% at 1 h and 74% over a 24-h period). Initially, the mutant secreted more carboxyl- than hydroxyl-linked glucuronide, but the ratio reached that of control animals after 24 h. The rates of formation of both types of hydroxyetianic acid glucuronide by hepatic microsomes from mutant rats were similar or even slightly higher than those of control microsomes. These findings indicate that bile acid 3-O-glucuronides, but probably not carboxyl-linked glucuronides, are secreted into bile by a transport system shared with organic anions such as conjugated bilirubin and dibromosulphthalein, but different from that for amino acid-conjugated bile acids.

Mechanism of cholic acid protection against lithocholate induced intrahepatic cholestasis

Article

Jan 1978
GASTROENTEROLOGY

Effective glucuronidation of 6α-hydroxylated bile acids by human hepatic and renal microsomes

Article

Jan 1988
Eur J Biochem

The glucuronidation of bile acids is an established metabolic pathway in different human organs. The hepatic and renal UDP-glucuronyltransferase activities vary according to the bile acids concerned. Thus, hyodeoxycholic acid is clearly differentiated from other bile acids by its high rate of glucuronidation and elevated urinary excretion in man. To determine whether such in vivo observations are related to variations in bile acid structure, human hepatic and renal microsomes were prepared and time courses of bile acid glucuronidation measured with the bile acids possessing hydroxyl groups in different positions. Eleven [24-14C]bile acids were chosen or synthesized in respect of their specific combination of hydroxyl and oxo groups at the 3, 6, 7 and 12 positions and of their α or β hydroxyl configurations. The results clearly demonstrate that bile acids with an hydroxyl group in the 6a position underwent a high degree of glucuronidation. Apparent kinetic Km and Vmax values for UDP-glucuronyltransferase activities ranged over 78–66 μM and 1.8–3.3 nmol · min−1· mg−1 protein in the liver and over 190–19 μM and 0.5–9.2 nmol · min−1· mg−1 protein in the kidney. All the other bile acids tested, each of which possessed a 3α-hydroxyl group and whose second or third hydroxyl was bound at the 6β, 7 or 12 positions, were glucuronidated to a degree far below that of the 6α-hydroxylated bile acids. We conclude that an active and highly specific UDP-glucuronyltransferase activity for 6α-hydroxylated bile acids exists in human liver and kidneys. Moreover, this activity results in the linkage of glucuronic acid to the 6α-hydroxyl group and not to the usual 3α-hydroxyl group of bile acids.

6α-Glucuronidation of hyodeoxycholic acid by human liver, kidney and small bowel microsomes

Article

Sep 1987
Biochim Biophys Acta Lipids Lipid Metabol

Kinetic constants for the glucuronidation of hyodeoxycholic acid in man were determined using microsomal preparations of liver, kidney and small bowel. The affinity of hyodeoxycholic acid for the microsomal hepatic and extrahepatic enzymes was in the same range as previously observed for the monohydroxy bile acid lithocholic acid and about 3–14-times the affinity for the dihydroxy bile acids chenodeoxycholic, deoxycholic and ursodeoxycholic acids. The Vmax values for glucuronidation of hyodeoxycholic acid with hepatic microsomes were 10–30-times higher and with kidney microsomes 50–110-times higher than for the bile acids lacking a 6α-hydroxy group. The site of glucuronidation was determined by gas chromatographic-mass spectrometric analysis of derivatives of products formed after periodate and chromic acid oxidation. Hyodeoxycholic acid glucuronides synthesized with microsomal preparations from the three organs were all found to be conjugated at the 6α position. This has previously been shown to be the site of glucuronidation of endogenous hyodeoxycholic acid glucuronide excreted in urine.

Pathogenesis of lithocholate- and taurolithocholate-induced intrahepatic cholestasis in rats

Article

Nov 1978
GASTROENTEROLOGY

The intrahepatic cholestasis induced by lithocholic acid and taurolithocholic acid is associated with a bizarre distortion of the bile canalicular membrane. The hypothesis that the physiological and morphological abnormalities observed are attributable to biochemical alterations of the bile canalicular membrane was investigated. In a direct comparative study, lithocholic acid and taurolithocholic acid were administered intravenously to male rats for 15, 30, or 60 min at a rate of 0.2μmole per min per 100 g of body weight. The liver cell plasma membranes were subsequently separated into two fractions, one rich in the bile canalicular membrane. The lipid composition of the bile and the bile canalicular membrane was analyzed, as well as membrane polypeptide profile and the activities of certain membrane enzymes. Lithocholic acid cholestasis was preceded by an initial choleresis in the first 30 min, which was assciated with an increased biliary secretion rate of bile acids, but not phospholipid or cholesterol. Lithocholic acid infusion was associated with a significant and progressive decrease in Na+ + K+-adenosine triphospatase, Mg2+-adenosine triphosphatase, and leucine aminopeptidase activities of the bile canalicular membrane. Free lithocholic acid was also incorporated into the membrane until it reached about 400 nmoles of lithocholic acid per mg of membrane protein after 30 min of lithocholic acid infusion, and the cholesterol content was increased by 6- to 7-fold with no changes in the membrane polypeptide profile or phospholipid content, as compared to control membrane. Taurolithocholic acid did not induce an initial choleresis and did not change the biliary secretion rate of bile acids, phospholipid, or cholesterol. Taurolithocholic acid did not alter the activity of any of the above membrane enzymes, nor was it incorporated into the isolated bile canaliculus. It did, however, result in a more than 2-fold increase in cholesterol content within 30 min, whereas no change was observed in the membrane polypeptide profile or phospholipid content, as compared to control membrane. It is suggested that the changes in the molecular structure of the bile canalicular membrane, specifically the increase in the cholesterol to phospholipid ratio, may be the cause for both the lamellar transformation of the bile canalicular membrane and the subsequent cholestasis in both models.

Enzymatic Sulphation of Bile Salts in Man

Article

Feb 1979

An investigation of the occurrence of glycolithocholate sulphotransferase in the human gastrointestinal tract and kidney is described. In addition to in the liver, glycolithocholate sulphotransferase was found in the small intestine, but no activity could be detected in the gastric mucosa, colonic mucosa, or kidney.

Cholesterol in acute cholestasis induced by taurolithocholic acid. A cytochemical study in transmission and scanning electron microscopy

Article

May 1978

Rats were given intravenous injections of a single dose of sodium taurolithocholate, and an almost total cholestasis appeared after 10 minutes and lasted for 3 hours after the injection; then the choleresis began again and 24 hours after the injection, normal values of bile flow were restored. Ultrastructural analysis of the liver during the acute cholestasis and the restoration phase showed, beside usual modifications found in most cases of cholestasis, the "characteristic" alterations of sodium taurolithocholate-induced cholestasis. Cytochemical procedures were used, both in transmission and in scanning electron microscopy, in order to delineate the possible participation of free cholesterol in these cellular modifications. After Williamson's reaction procedure (Williamson JR:J Ultrastruct Res 27:118, 1969), not only were cholesterol-digitonin complexes found in large numbers, both in the hepatocytic cytoplasm and in the biliary canaliculi, but also their morphologic appearance revealed several new features: dark sticks and dark lamellae, frequently adsorbed on the outer surface of crystalline clear material were observed by transmission electron microscopy, and plugs, obliterating parts of biliary canaliculi, were observed using scanning electron microscopy. These observations seem to indicate that a significant amount of free cholesterol is released into the hepatocyte cytoplasm and into canalicular lumina within a few minutes after the infection of sodium taurolithocholate, probably originating from the hepatocytic membranes, especially from those limiting the canalicular lumen. Such a drastic modification in the chemical constitution of these membranes should coincide with a marked modification of their active and passive transport ability.

Subcellular pathology of rat liver in cholestasis and choleresis induced by bile salts. 1. Effects of lithocholic, 3beta-hydroxy-5-cholenoic, cholic, and dehydrocholic acids

Article

Apr 1977

Cholestasis or choleresis was induced in the rat by intravenous infusion (0.05 to 0.2 mumole per minute per 100 grams of body weight) of sodium taurolithocholate, 3beta-hydroxy-5-cholenoate, taurocholate, and dehydrocholate either singly or in combination after or without cannulation of the common bile duct. Bile flow was monitored and ultrastructural changes were examined by scanning and transmission electron microscopy up to 3 hours after bile salt administration. Taurolithocholate induced acute cholestasis and ultrastructural alterations consisting primarily of dilation of bile canaliculi, loss of canalicular microvilli, and lamellar transformation of the canalicular membrane. Occasionally, crystalline precipitates were present within the canalicular lumen and in the pericanalicular region of hepatocytes. 3beta-Hydroxy-5-cholenoate caused similar but less severe ultrastructural changes than those induced by taurolithocholate. Dehydrocholate had a greater choleretic effect than taurocholate, but neither induced noteworthy ultrastructural change. When infused simultaneously with taurolithocholate, taurocholate reversed cholestasis and largely prevented development of the ultrastructural changes induced by taurolithocholate. In contrast, simultaneous infusion of dehydrocholate prevented neither cholestasis nor development of the ultrastructural changes induced by taurolithocholate, which were more striking than those caused by taurolithocholate or 3beta-hydroxy-5-cholenoate alone. In addition, structural changes associated with cholestasis induced by these bile salts either singly or in combination were more pronounced and frequent in the periportal zone than elsewhere in the hepatic lobule. These results suggest that both taurolithocholate and 3beta-hydroxy-5-cholenoate induce cholestasis by affecting the structural and functional integrity of the bile canalicular membrane and also, in part, by forming untransportable precipitates. The contrasting effects of taurocholate and dehydrocholate on taurolithocholate-induced changes suggest that taurocholate overcomes the effect of taurolithocholate by solubilizing it into mixed micelles, but dehydrocholate and its metabolites have little or no such effect. The intralobular variation in severity of ultrastructural changes probably reflects the accumulation of bile salts in greater concentrations in hepatocytes near the portal triads.

Identification of bile acids in the serum and urine in cholestasis. Evidence for 6α-hydroxylation of bile acids in man

Article

Mar 1976

In this qualitative study of the pattern of bile acid excretion in cholestasis, methods are described for the isolation of bile acids from large volumes of urine and plasma. The bile acids were subjected to a group separation and identified by combined gas chromatography-mass spectrometry. The techniques were developed to allow identification of the minor components of the bile acid mixture. Four bile acids that have not previously been described in human urine and plasma were detected, namely 3beta, 7alpha-dihydroxy-5beta-cholan-24-oic acid, 3alpha, 6alpha-dihydroxy-5beta-cholan-24-oic acid (hyodeoxycholic acid), 3alpha, 6alpha, 7alpha-trihydroxy-5beta-cholan-24-oic acid (hyocholic acid) and 3alpha, 7beta, 12alpha-trihydroxy-5beta-cholan-24-oic acid. In addition three C27 steroids were found; 26-hydroxycholesterol and a trihydroxy cholestane, probably 5 beta-cholestane-3alpha, 7alpha, 26-triol were found in the sulphate fraction of plasma and urine. In the plasma sample, a sulphate conjugate of 24-hydroxycholesterol was found. The presence of these compounds probably reflects the existence of further pathways for bile acid metabolism. It is not yet known whether this is a consequence of the cholestasis or whether they are also present in normal man, at much lower concentrations.

Metabolism of lithocholic acid in the rat: formation of lithocholic acid 3-O-glucuronide in vivo

Abstract

Recommended publications

Lithocholate glucuronide is a cholestatic agent

Hepatic metabolism of short-chain bile acids. Inversion of the 3-hydroxyl group of isoetianic acid (...

Diglucuronide: a novel bile acid metabolite

Effect of Bile Acids on Calcium Efflux from Isolated Rat Hepatocytes and Perfused Rat Livers