Promotion of hepatocellular foci in female rats by chenodeoxycholic acid

Chenodeoxycholic acid (CDC), a dihydroxylated primary bile acid, was evaluated for promotional activity in the liver of rats using a two-stage initiation-promotion model. CDC is a primary bile acid that can attain high concentrations in serum and liver during induced or naturally occurring hepatocellular disorders. Female Sprague-Dawley rats were injected once (i.p.) with diethylnitrosamine (DEN, 150 mg/kg) or sterile physiologic saline (SAL, 0.85% NaCl). Two weeks later, rats in each group were placed into one of two subgroups and fed either NIH-31 mash (Control) or NIH-31 mash containing 0.5% CDC for a 10 week period. At the end of the feeding period, blood and liver samples were collected for determination of bile acid profiles and quantitation of hepatocellular foci respectively. Serum samples were analyzed for concentrations of individual bile acids using a HPLC method that utilizes a post-column enzymatic reaction and fluorescence detection. Liver slices from the left hepatic lobe were stained for foci positive for placental glutathione S-transferase. In serum, significant increases occurred in concentrations of all forms of CDC and were accompanied by mild, insignificant increases in lithocholic acid. Decreased serum concentrations occurred in all forms of cholic and deoxycholic acids. Analysis of liver sections revealed that rats treated with DEN-CDC had significant increases in numbers and volume of foci compared to those treated with DEN-Control. For rats in groups DEN-CDC and DEN-Control, the numbers of foci per square centimeter were 32 and 12; per cubic centimeter, 2221 and 937; and the per cent volume of foci, 1.487 and 0.385 respectively. In this study, CDC was a promoter of hepatocellular foci. Because concentrations of CDC in liver and serum increase in a variety of hepatobiliary disorders, the possibility that increases in endogenous concentrations can enhance the formation of hepatocellular foci is being explored.