Effects of bile salts on plasma concentration of beta-endorphin-like immunoreactivity in men

The effects of bile salts on the release of beta-endorphin-like immunoreactivity (beta-END-LI) were investigated in men using a specific radioimmunoassay developed by the authors. Plasma beta-END-LI was determined after extraction by the acid-acetone method (recovery: 73 +/- 5%). Oral administration of 400 mg of sodium taurocholate caused a rise in plasma beta-END-LI from 9.9 +/- 0.5 pmol/liter to 21.3 +/- 1.2 pmol/liter after 30 min and 18.1 +/- 0.5 pmol/liter after 60 min, with return to the initial value after 90 min. Oral administration of chenodeoxycholic acid (CDCA) also increased plasma beta-END-LI from a basal level of 8.4 +/- 0.7 pmol/liter to 18.7 +/- 0.8 pmol/liter after 30 min. Oral administration of ursodeoxycholic acid (UDCA) increased plasma beta-END-LI from 7.3 +/- 0.3 pmol/liter to 30.6 +/- 0.2 pmol/liter after 30 min. In gel chromatography, the beta-END-LI released after UDCA administration separated into two components, which eluted in the same positions as human beta-lipotropin and human beta-endorphin, respectively. These results suggested that bile salts may participate the release of beta-END-LI.