Increased expression of ileal apical sodium-dependent bile acid transporter in postpartum rats.
The expression and activity of the apical ileal sodium-dependent bile acid transporter (asbt) was examined in the small intestine of control, pregnant, and lactating postpartum rats 2, 12, and 21 days after delivery. Western blot analysis of brush border membrane vesicles (BBMV) prepared from different regions of the small intestine demonstrated that expression of asbt was maximal in the most distal segments for all experimental groups, was not substantially affected in pregnant and 2-day postpartum rats, and was significantly increased in 12- and 21-day postpartum rats. Analysis of mRNA suggested that asbt protein was regulated at the posttranscriptional level in postpartum rats. Increased expression of asbt protein postpartum was maximal (approximately 2-fold) in the proximal region of the ileum, consistent with a 60% increase in taurocholate (TC) transport in BBMV from the proximal ileum in 14- to 21-day postpartum rats relative to control rats. Absorption of TC, determined from the intact proximal ileum using an intestinal loop model, demonstrated a 30% increase in TC uptake per unit weight of tissue in 14- to 21-day postpartum rats relative to control rats. Together with the marked increase in intestinal mass observed at peak lactation, these data indicate a significant increase in asbt-mediated reclamation of bile acids in the intestine of lactating rats.
Mottino
Aldo D
AD
Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky 40536-0305, USA.
Hoffman
Tim
T
Dawson
Paul A
PA
Luquita
Marcelo G
MG
Monti
Juan A
JA
Sánchez Pozzi
Enrique J
EJ
Catania
Viviana A
VA
Cao
Jingsong
J
Vore
Mary
M
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics*; D004041:Dietary Fats / Q000493:pharmacokinetics; D004764:Enterohepatic Circulation / Q000502:physiology; D005260:Female; D015870:Gene Expression / Q000502:physiology; D004763:Glucagon-Like Peptides; D007082:Ileum / Q000378:metabolism*; D007408:Intestinal Absorption / Q000502:physiology*; D007774:Lactation / Q000502:physiology; D008099:Liver / Q000502:physiology; D029363:Organic Anion Transporters, Sodium-Dependent; D010052:Ovariectomy; D010455:Peptides / Q000494:pharmacology; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy; D011388:Prolactin / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D027981:Symporters; D013656:Taurocholic Acid / Q000493:pharmacokinetics
D001647:Bile Acids and Salts; D002352:Carrier Proteins; D004041:Dietary Fats; D029363:Organic Anion Transporters, Sodium-Dependent; D010455:Peptides; D012333:RNA, Messenger; D027981:Symporters; C071908:sodium-bile acid cotransporter; D013656:Taurocholic Acid; D004763:Glucagon-Like Peptides; C015236:glucagon-like-immunoreactivity; D011388:Prolactin; D000469:Alkaline Phosphatase