Document Detail


Maternal apelin physiology during rat pregnancy: the role of the placenta.
MedLine Citation:
PMID:  20580085     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Apelin is a multifunctional peptide which is catabolized by the angiotensin-converting enzyme-related carboxypeptidase-2 (ACE2). The peptide is well known for its hemodynamic effects and its role in energy and fluid homeostasis. Pregnancy is a state of dramatically altered maternal hemodynamics and metabolism, but the role of apelin is unknown. To gain further insight in apelin physiology, we investigated relative tissue expression, plasma clearance and metabolic pathways of apelin in pregnant rats.
METHODS: We measured maternal plasma apelin levels throughout normal rat gestation and examined relative apelin gene expression in several tissues, including the placenta. We documented apelin clearance using radiolabeled apelin and assessed maternal plasma levels in rats that underwent surgical reduction of the fetoplacental mass, thereby further examining the role of the placenta in apelin clearance. Finally, we localized apelin and ACE2 in the placenta and mesometrial triangle using immunohistochemistry.
RESULTS: Maternal apelin plasma concentrations dropped by 50% between mid- and late gestation. Apelin expression was comparable between non-pregnant and late-pregnant rats in non-reproductive tissues. The placenta showed low apelin gene expression compared to brain tissue. Apelin clearance was enhanced in term gestation as evidenced by a steeper decline of the slow phase of the elimination curve of radiolabeled apelin. Compared to sham-operated dams, maternal plasma apelin was raised by 23% in late-pregnant rats in which half of the fetoplacental units were removed at day 16 of gestation. ACE2 mRNA expression was detectable in late- but not mid-pregnancy placental tissue; immunohistochemically, ACE2 was primarily localized in the smooth muscle layer of fetal arterioles in the labyrinth.
CONCLUSION: Maternal circulating apelin drops considerably between mid- and late- pregnancy owing to faster clearance. The current data suggest a role for placental ACE2 in the accelerated apelin metabolism.
Authors:
T Van Mieghem; R van Bree; E Van Herck; R Pijnenborg; J Deprest; J Verhaeghe
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-06-26
Journal Detail:
Title:  Placenta     Volume:  31     ISSN:  1532-3102     ISO Abbreviation:  Placenta     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-06     Completed Date:  2010-11-24     Revised Date:  2011-08-03    
Medline Journal Info:
Nlm Unique ID:  8006349     Medline TA:  Placenta     Country:  England    
Other Details:
Languages:  eng     Pagination:  725-30     Citation Subset:  IM    
Affiliation:
Department of Obstetrics and Gynecology, Health Campus Gasthuisberg, Katholieke Universiteit Leuven, Herestraat 49, Leuven, Belgium. tim.vanmieghem@uzleuven.be
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MeSH Terms
Descriptor/Qualifier:
Animals
Carrier Proteins / blood*,  pharmacokinetics
Female
Homeostasis
Metabolic Clearance Rate
Peptidyl-Dipeptidase A / metabolism*
Placenta / metabolism*
Pregnancy / blood*
Pregnancy Reduction, Multifetal
Rats
Rats, Sprague-Dawley
Chemical
Reg. No./Substance:
0/Apln protein, rat; 0/Carrier Proteins; EC 3.4.15.1/Peptidyl-Dipeptidase A; EC 3.4.17.-/angiotensin converting enzyme 2

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