Enterohepatic Circulation of Estrogens in the Domestic Pig, Sus Scrofa
Ruoff, William Louis
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https://hdl.handle.net/2142/71459
Description
Title
Enterohepatic Circulation of Estrogens in the Domestic Pig, Sus Scrofa
Author(s)
Ruoff, William Louis
Issue Date
1988
Doctoral Committee Chair(s)
Bahr, Janice
Department of Study
Physiology and Biophysics
Discipline
Physiology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Animal Physiology
Abstract
Enterohepatic circulation (EHC) of estrogen involves secretion of estrogen in bile by the liver, release of bile from the gallbladder into the gastrointestinal tract, absorption of estrogen in bile from the gastrointestinal tract into venous blood going to the liver, and secretion of estrogen by the liver into bile or into the peripheral circulation.
The objective of this thesis was to determine the influence of EHC of estrogen on the concentration of biologically active estrogen in the peripheral circulation of the pig. In the experiments, exogenous estradiol or natural bile estrogens were placed in the gastrointestinal tract of pre-pubertal gilts and concentrations of estrodiol-17$\beta$ (E2), estrone (E1), estrone sulfate (E1S), estradiol glucuronide (E2G) and estrone glucuronide (E1G) were determined in plasma from the hepatic portal and jugular veins. In addition, in pregnant pigs, the effect of inhibition of EHC on concentrations of estrogens in peripheral plasma was determined.
Natural bile from pre-pubertal or pregnant pigs contained E2, E1, E1S, E2G and E1G. More than 94% of the estrogen in bile from pigs was conjugated to glucuronide or sulfate. Unconjugated estrogens were absorbed from the gut of gilts within minutes. Conjugated estrogens required deconjugation by gut bacteria prior to absorption and were absorbed from the gut of gilts over a period of several hours. More than 94% of unconjugated E2 or E1 absorbed from the gut was conjugated in the hepatic portal vein. All unconjugated E2 or E1 absorbed from the gut of gilts was conjugated in the jugular vein. Absorption of exogenous E2 or natural bile estrogens from the gut or gilts resulted in increased concentrations of conjugated E2 and E1 in the jugular vein. After absorption of natural bile estrogens from the gut of gilts, concentrations of estrogens in bile increased. Stimulation of release of this bile into the gastrointestinal tract of gilts caused a second EHC which increased concentrations of conjugated E2 and E1 in the jugular vein. An attempt to inhibit EHC of estrogens in pregnant pigs by the altering diet did not cause a detectable change of concentrations of conjugated and unconjugated estrogen in peripheral plasma. (Abstract shortened with permission of author.)
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