Effects of contraceptive steroids and pregnancy on bile composition and kinetics in the baboon

Abstract

The effects of subcutaneous implants of ethinyl estradiol (EE) and norethindrone (NE) alone and in combination and pregnancy on bile composition and kinetics were studied in the baboon. Treatment with EE significantly (p less than .01) reduced biliary cholesterol; the addition of NE enhanced this effect. NE alone however produced a slight increase in biliary cholesterol. During the third trimester of pregnancy both biliary cholesterol and the lithogenic index were significantly (p less than .05) decreased. The chenodeoxycholic acid pool (CAP) size was significantly (p less than .05) decreased by EE and further decreased by EE plus NA (p less than .01). NET alone resulted in an increase in CAP size. CAP size was also reduced by pregnancy though the reduction was not significant (p less than .05) until the third trimester. EE plus NE significantly (p less than .05) increased deoxycholic acid pool (DAP) size though NE along could not sustain this increase. DAP size in pregnancy decreased during the third trimester. No net change in total bile acid pool size was observed during any of the periods of EE or EE plus NE though there was a significant (p less than .05) net decrease in total bile salt pool size during the third trimester of pregnancy. The relevance of the findings to the formation of gallstones in the human female is discussed.