Formation of cholic acid and chenodeoxycholic acid from 7 alpha-hydroxycholesterol and 27-hydroxycholesterol by primary cultures of human hepatocytes.
It has been suggested that chenodeoxycholic acid is preferentially formed by the alternative or 'acidic' pathway of bile acid biosynthesis starting with 27-hydroxylation of cholesterol, while cholic acid is derived from 7 alpha-hydroxycholesterol which initiates the 'neutral' pathway. We have studied bile acid formation from each of these precursors using human hepatocytes cultured in a novel sandwich collagen configuration. Culture supernatants were analyzed using capillary gas chromatography and gas chromatography-mass spectrometry. 27-Hydroxycholesterol and 7 alpha-hydroxycholesterol were both found to be efficiently converted to cholic acid as well as chenodeoxycholic acid. Analysis of acidic intermediates after addition of 7 alpha-hydroxycholesterol to the cultures revealed a significant increase of side-chain oxygenated C24- and C27-steroids with a 3-oxo-7 alpha-hydroxy-delta 4-ring structure. These data indicate that (i) the 'neutral' pathway is connected to the 'acidic' pathway by side-chain oxidation of C27-steroids with a 3-oxo-7 alpha-hydroxy-delta 4-ring structure and that (ii) the relative formation of cholic acid and chenodeoxycholic acid is regulated by metabolic events distal to the initial hydroxylation at either position 7 or position 27 of the cholesterol molecule.
Sauter
G
G
Department of Medicine II, Klinikum Grosshadern, University of Munich, Germany.
Fischer
S
S
Pahernik
S
S
Koebe
H G
HG
Paumgartner
G
G
D000328:Adult; D002478:Cells, Cultured; D002635:Chenodeoxycholic Acid / Q000096:biosynthesis; D019826:Cholic Acid; D002793:Cholic Acids / Q000096:biosynthesis*; D002849:Chromatography, Gas; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006888:Hydroxycholesterols / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
D002793:Cholic Acids; D006888:Hydroxycholesterols; D002635:Chenodeoxycholic Acid; C011724:cholest-5-en-3 beta,7 alpha-diol; C076996:27-hydroxycholesterol; D019826:Cholic Acid