Open AccessAbsorption and Enterohepatic Circulation of Neutral Steroids in the Rat
Author(s) -
Eriksson Håkan
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01331.x
Subject(s) - enterohepatic circulation , pregnenolone , medicine , endocrinology , chemistry , corticosterone , metabolism , urine , absorption (acoustics) , steroid , hormone , biology , physics , acoustics
The absorption of labelled pregnenolone, corticosterone, pregnenolone sulphate and deoxycorticosterone sulphate after intragastric, intraduodenal and intracaecal injection was studied in female bile fistula rats. Efficient absorption was observed in all cases. Evidence was obtained for the absorption of both free steroids and sulphates from the small intestine, free steroids being absorbed more rapidly. Partial hydrolysis of the sulphates, probably bacterial, occurred in the intestine. Radioactivity in the portal blood was distributed between the free, glucuronide, monosulphate and diconjugate fractions. Glucuronides were present in the bile but not in faeces and urine. The enterohepatic circulation of labelled pregnenolone and corticosterone was studied in a series of rats consisting of five animals connected by cannulae between the bile duct of one rat and the duodenum of the next rat. The average time for an enterohepatic circulation was calculated to be 3—4 h. The ratio between radioactivities eliminated in faeces and urine increased progressively and markedly with each enterohepatic cycle, as did the ratio between conjugated and free steroids. It is concluded that the steroids undergo extensive metabolism in each enterohepatic cycle and that labelled steroids injected into rats are unlikely to be fully mixed with the endogenous pools before being excreted.