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World J Gastroenterol. Feb 21, 2009; 15(7): 817-828
Published online Feb 21, 2009. doi: 10.3748/wjg.15.817
Excretion of biliary compounds during intrauterine life
Rocio IR Macias, Jose JG Marin, Maria A Serrano
Rocio IR Macias, Jose JG Marin, Maria A Serrano, Laboratory of Experimental Hepatology and Drug Targeting, CIBERehd, University of Salamanca, Salamanca 37007, Spain
Author contributions: All authors contributed equally to this paper.
Correspondence to: Rocio IR Macias, Department of Physiology and Pharmacology, Campus Miguel de Unamuno E.I.D. S-09, Salamanca 37007, Spain.
Telephone: +34-923-294674
Fax: +34-923-294669
Received: November 17, 2008
Revised: January 10, 2009
Accepted: January 17, 2009
Published online: February 21, 2009

In adults, the hepatobiliary system, together with the kidney, constitute the main routes for the elimination of several endogenous and xenobiotic compounds into bile and urine, respectively. However, during intrauterine life the biliary route of excretion for cholephilic compounds, such as bile acids and biliary pigments, is very poor. Although very early in pregnancy the fetal liver produces bile acids, bilirubin and biliverdin, these compounds cannot be efficiently eliminated by the fetal hepatobiliary system, owing to the immaturity of the excretory machinery in the fetal liver. Therefore, the potentially harmful accumulation of cholephilic compounds in the fetus is prevented by their elimination across the placenta. Owing to the presence of detoxifying enzymes and specific transport systems at different locations of the placental barrier, such as the endothelial cells of chorionic vessels and trophoblast cells, this organ plays an important role in the hepatobiliary-like function during intrauterine life. The relevance of this excretory function in normal fetal physiology is evident in situations where high concentrations of biliary compounds are accumulated in the mother. This may result in oxidative stress and apoptosis, mainly in the placenta and fetal liver, which might affect normal fetal development and challenge the fate of the pregnancy. The present article reviews current knowledge of the mechanisms underlying the hepatobiliary function of the fetal-placental unit and the repercussions of several pathological conditions on this tandem.

Keywords: Bile acids, Bilirubin, Foetus, Liver, Placenta