Experimental protoporphyria: effect of bile acids on liver damage induced by griseofulvin.

The effect of bile acids administration to an experimental mice model of Protoporphyria produced by griseofulvin (Gris) was investigated. The aim was to assess whether porphyrin excretion could be accelerated by bile acids treatment in an attempt to diminish liver damage induced by Gris. Liver damage markers, heme metabolism, and oxidative stress parameters were analyzed in mice treated with Gris and deoxycholic (DXA), dehydrocholic (DHA), chenodeoxycholic, or ursodeoxycholic (URSO). The administration of Gris alone increased the activities of glutathione reductase (GRed), superoxide dismutase (SOD), alkaline phosphatase (AP), gamma glutamyl transpeptidase (GGT), and glutathione-S-transferase (GST), as well as total porphyrins, glutathione (GSH), and cytochrome P450 (CYP) levels in liver. Among the bile acids studied, DXA and DHA increased PROTO IX excretion, DXA also abolished the action of Gris, reducing lipid peroxidation and hepatic GSH and CYP levels, and the activities of GGT, AP, SOD, and GST returned to control values. However, porphyrin accumulation was not prevented by URSO; instead this bile acid reduced ALA-S and the antioxidant defense enzymes system activities. In conclusion, we postulate that DXA acid would be more effective to prevent liver damage induced by Gris.

[Behavior of the arterial wall of non-selected rats, old and young, subjected to potentially atherogenic dietary factors]. / Comportamento da parede arterial de ratos não selecionados, idosos e jovens, frente a fatores dietéticos potencialmente aterogênicos.

PURPOSE: To evaluate the arterial wall behaviour in old and young rats submitted to a ration containing atherogenic factors (cholesterol, dehydrocolic acid and vitamin D2). MATERIAL AND METHODS: 20 old male albino rats (approximately one year old) were grouped as follows: group 1, five control animals; group 2, five animals receiving a ration with cholesterol plus dehydrocolic acid; group 3, ten rats receiving an equivalent ration added to vitamin D2. Equivalent groups (4, 5 and 6), with an identical number, but younger animals (2 months old), were compared to the former. Groups 4, 5 and 6 were treated in the same way of groups 1, 2 and 3. After two months, all the groups were bled for cholesterol (CT), triglycerides and HDL dosage. Afterwards, they were sacrificed and the histopathological analysis of the aorta, heart, and lungs executed by the hematoxylin-eosin, Verhoeff and acetic orcein methods. RESULTS: Serum cholesterol (average) was 52 mg/dl in group 1 and 56.6 in group 4. Groups 3 and 6 presented about two times the serum cholesterol level observed in control groups and groups 2 and 5 three times control groups. When the old and young animals CT averages were compared, no significant differences were observed. However, when the influences of the atherogenic factors were analyzed, significant differences appeared; the simultaneous administration of dehydrocolic acid and cholesterol tripled the value of CT, and the use of vitamin D2, applied with other factors, raised CT only to the double. No atherosclerotic lesions were obtained but only Monckberg atherosclerosis lesions, sclerosis type (calcification of the medium stratum) in those animals who received vitamin D2. CONCLUSION: The arterial wall of non-selected old and young rats behaved equally when submitted to a ration containing cholesterol, dehydrocolic acid and vitamin D2. They developed calcified lesions of atherosclerotic type, in spite of a prolonged hypercholesterolemia.

Effects of sodium taurocholate and sodium dehydrocholate on bile flow, lipid and bilirubin secretion in sheep.

The investigation was performed on 8 sheep with implanted catheters in the common bile duct and in the cystic duct. Sodium taurocholate and sodium dehydrocholate were infused into the jugular vein at the rate of 50 mumol/min for 20 min. Directly after the termination of the sodium taurocholate infusion, the volume of the secreted bile increased from 8.4-9 microliters.kg-1.min-1 to the highest mean value of 17.8 microliters.kg-1, min-1, with a simultaneous increase in the concentration of cholates from 1.71 mmol/l to 4.82 mmol/l and bilirubin from 271.1 mumol/l to 461.7 mumol/l. The concentration of cholesterol and phospholipids in the bile also increased, but did not reach statistically significant values. The infusion of sodium dehydrocholate caused an increase in the bile secretion to the highest mean value of 20.59 microliters.kg-1.min-1 with a simultaneous decrease in the concentration of bilirubin to 148.75 mumol/l, cholesterol to 233.0 micrograms/ml, phospholipids to 56.11 micrograms/ml and cholate to 1.0 mmol/l. The results show that biliary secretion of phospholipids, cholesterol and bilirubin is dependent on the secretion of sodium taurocholate rather than on dehydrocholic acid.

Influence of dehydrocholic acid on the secretion of bile acids and biliary lipids in rats.

This study investigated the influence of dehydrocholic acid (DHCA) infusion on the secretion of endogenous bile acids, and biliary lipids in rats in an attempt to explain the reduction of biliary lipid secretion associated with DHCA infusion. DHCA increased bile flow and the bile acids produced during the infusion were composed of three hydroxy-oxo metabolites (83-93%), and cholic acid (6-14%). Very little DHCA was secreted unchanged (less than 2%). The secretions of all the endogenous biliary bile acids were diminished within 30-60 min of infusion. DHCA furthermore reduced the secretion of exogenous cholic acid when co-infused with DHCA. Phospholipid secretion declined to an undetectable amount and cholesterol declined to 10% of the base value by the end of the infusion. The reduction of biliary lipid secretion during DHCA infusion was attributed to the diminished secretion of endogenous bile acids. These data show that DHCA infusion induces choleresis associated with reduced secretion of endogenous and/or exogenous biliary components.

The biotransformed metabolite profiles in blood after intravenous administration of dehydrocholic acid.

One gram of dehydrocholic acid was injected intravenously into two patients with percutaneous transhepatic cholangial drainage, and the biotransformed metabolites profiles over a 120-min period in serum and bile were analyzed. In serum unconjugated 3 alpha-hydroxy-7,12-dioxo-cholanoic acid (3 alpha-OH-7,12-OXO) acid was markedly increased after the injection of dehydrocholic acid, and reached about 80 microM within 30 min. On the other hand, conjugated 3 alpha, 7 alpha-dihydroxy-12-oxo-cholanoic acid (3 alpha,7 alpha-OH-12-OXO) was consecutively increased with lag time to an elevation of 3 alpha-OH-7,12-OXO. In bile, the major constituent of metabolites was conjugated 3 alpha,7 alpha-OH-12-OXO (more than 90% of the excreted metabolites), while conjugated 3 alpha-OH-7,12-OXO was detected as minor constituent. Therefore, between bile and serum, there was great difference in biotransformed metabolites profiles. The mechanism of elevation of unconjugated 3 alpha-OH-7,12-OXO in serum remains obscure, but this new finding raised a question as to whether organ-reducing 3-keto group of dehydrocholic acid is restricted to the liver.

The protective effect of experimental subarachnoid haemorrhage on sodium dehydrocholate-induced blood-brain barrier disruption.

The potential interactive effects between subarachnoid hemorrhage (SAH) and blood brain barrier (BBB) disruption were studied in a rat model. Experimental subarachnoid hemorrhage was produced in twenty rats (experimental group) by the intracisternal injection of blood. In ten additional rats (control group), saline was administered in place of blood. Analysis of mean blood pressure (MBP), intracranial pressure (ICP) and cerebral perfusion pressure (CPP) demonstrated an increase in ICP and MBP and a drop in CPP in all animals following intracisternal injection. Subsequent infusion of the left internal carotid artery with sodium dehydrocholate resulted in blood-brain barrier (BBB) disruption in both groups as evidenced by Evans blue staining of the infused cortex. The extent of BBB disruption was significantly greater in the control group than the experimental group. Analysis of the experimental group demonstrated that animals with the lowest pre-SAH MBP and the lowest CPP during the maximum blood pressure response to SAH demonstrated the greatest resistance to experimental BBB disruption. The possibility of ischemia as a contributing factor in BBB protection subsequent to SAH is discussed.

Intravenous dehydrocholate tolerance test in patients with liver disease.

The disappearance of intravenously administered dehydrocholate was studied in 13 healthy subjects and 23 patients with chronic liver disease. Serum dehydrocholate was determined by the enzymatic method using 3 alpha-hydroxysteroid dehydrogenase. Following the loading dose of dehydrocholate, serum dehydrocholate and 3 alpha-hydroxy bile acid were assayed at five minute intervals for 15 minutes. During this 15 minute period, dehydrocholate decreased and 3 alpha-hydroxy bile acid increased. The disappearance of the dehydrocholate was delayed in patients with chronic liver disease, and the 5-minute retention value was significantly high in cirrhosis patients.

Intracarotid dehydrocholate infusion: a new method for prolonged reversible blood-brain barrier disruption.

An animal model for prolonged reversible blood-brain barrier (BBB) disruption has been developed. The external carotid arteries of Osborn-Mendel rats were catheterized in a retrograde manner. Varying concentrations of sodium dehydrocholate were infused into the internal carotid artery by this technique. BBB disruption was evaluated qualitatively by the appearance in the infused hemisphere of the systemically administered dyes Evans blue and sodium fluorescein and quantitatively by the ratio of counts of the technetium-labeled chelate of diethylenetriaminepentaacetic acid (99mTc-DTPA) in the infused to the noninfused hemisphere. The ability of sodium dehydrocholate to disrupt the BBB was documented with all three markers. As the concentration of the infused dehydrocholate was increased, both the incidence and the degree of BBB disruption increased. Reversibility of BBB disruption was evaluated by the administration of sodium fluorescein and 99mTc-DTPA at varying times after BBB disruption. Depending on the concentration of the infused sodium dehydrocholate, altered BBB permeability can be maintained for over 3 days. This new model of prolonged reversible BBB disruption deserves further investigation both for basic studies of the BBB and for therapeutic studies of drug delivery into the central nervous system.

[The clinical significance of radioimmunologically determined serum bile acids as a new liver function test and the development of a new intravenous sulfolithoglycocholic acid (SLGC) stimulation test]. / Die klinische Bedeutung radioimmunologisch bestimmter Serumgallensäuren als neuer Leberfunktionstest und die Entwicklung eines neuen intravenösen Sulfolithoglykocholsäure-(SLCG-) Stimulationstests.

Cholylglycin (CG-) and SLCG levels were measured in patients with various biopsy-confirmed liver and bile disease. SLCG values were found to be more sensitive, and to distinguish clearly between steatosis hepatis and normals, as well as between cirrhosis hepatis, with and without, portal hypertension. Correlations between the common liver tests and the SLCG levels were poor, but a clear distinction was possible between the various histologically defined liver diseases. The paper concludes with a description of a new method of stimulating the SLCG values, intravenously. Using this method, it is possible to keep consumption of material and time and incommodities inflicted to the patient, as low as possible. Nevertheless staging of parenchymatous liver diseases, is feasible.

Glucose reabsorption from bile. Evidence for a biliohepatic circulation.

Glucose is absent from human bile and present in low concentrations in bile from the rat. To study the mechanisms of this blood-bile glucose concentration difference, infusions of glucose were administered i.v. to 300-400 g male Sprague-Dawley rats with ligated renal pedicles and to two postcholecystectomy patients with indwelling t-tubes. Glucose was assayed in plasma, bile, and rat liver by a hexokinase method specific for D-glucose. In man, glucose was detected in bile when plasma glucose increased above 350 mg/100 ml. In animals studies, low concentrations of bile glucose were observed at plasma levels between 100 and 300 mg/100 ml. However, when plasma concentrations increased between 400 and 900 mg/100 ml, glucose appeared more rapidly in bile, defining by extrapolation an apparent plasma glucose threshold of 280 mg/100 ml. Intraportal phlorizin, a competitive inhibitor of glucose transport, significantly increased bile glucose concentrations. Plasma-bile concentration differences were also observed in rats after i.v. [3-14C]O-methyl glucose (3-O-MG) but not after [3H]mannitol. Hepatic glucose levels were never lower than plasma levels and liver-plasma 3-O-MG ratios were 0.92 +/- 0.22 indicating that entry of glucose and 3-O-MG into hepatocyte water was not limiting. Furthermore, when sodium dehydrocholate augmented canalicular secretion, biliary glucose excretion increased proportionally suggesting that glucose entry into bile was not impeded. When estimates of hepatic glucose secretion were compared with biliary glucose excretion, the latter increased progressively when estimated secretion rates exceeded 50 micrograms/min or when phlorizin was given. Finally, during bile stop-flow experiments, [3-14C]O-MG and [14C]glucose were selectively removed from bile compared with [3H]mannitol. The findings suggest that glucose and 3-O-MG are reabsorbed from bile after entry at the hepatocyte, accounting for their low bile-plasma ratio. The biliary glucose transport process may be described by Michaelis-Menten kinetics and is analogous to recently defined kinetics for renal tubular reabsorption of glucose. These studies provide evidence that certain products of bile secretion may undergo a "biliohepatic" circulation.

Alterations in biliary lipids of mice during dehydrocholic acid feeding.

Mice were fed a lithogenic diet consisting of Purina chow and 0.5% dehydrocholic acid (DHA group). Controls received Purina chow. Every 2 wk for 20 wk animals were killed, and biliary phospholipid, cholesterol, and bile salt concentrations were determined, as well as the extent of gallstone formation. With time there was a gradual, significant decline in the concentration and the relative composition of phospholipid in both groups compared with initial values. There was a significant increase in biliary cholesterol concentration and relative amount in the DHA group compared with the control. No significant differences were found in the relative amounts of bile salt or phospholipid between the two groups. Feeding DHA resulted in an increased concentration of bile salts and the sum of measured lipid compared with controls. After 8 wk, gallstones were found in approximately 60% of autopsied animals and correlated with increased cholesterol concentration. Our data support the hypothesis that there is a component of cholesterol secretion that may not be bile salt- or phospholipid-dependent. Our data also suggest that biliary phospholipid secretion decreases with age.