Changes in the expression of intestinal iron transport and hepatic regulatory molecules explain the enhanced iron absorption associated with pregnancy in the rat.
BACKGROUND
Iron absorption increases during pregnancy to cater for the increased iron requirements of the growing fetus.


OBJECTIVE
To investigate the role of the duodenal iron transport molecules and hepatic regulatory molecules in coordinating the changes in iron absorption observed during pregnancy.


METHODS
Rats at various days of gestation and 24-48 hours post-partum were examined for hepatic expression of hepcidin, transferrin receptors 1 and 2, and HFE (the gene mutated in the most prevalent form of hereditary haemochromatosis), and duodenal expression of divalent metal transporter 1 (DMT1), duodenal cytochrome b (Dcytb), iron regulated mRNA (Ireg1), and hephaestin (Hp) by ribonuclease protection assay, western blotting, and immunohistochemistry.


RESULTS
Decreased hepatic non-haem iron and transferrin saturation and increased expression of transferrin receptor 1 in the liver indicated a progressive reduction in maternal body iron stores during pregnancy. Duodenal expression of the iron transport molecules DMT1, Dcytb, and Ireg1 increased during pregnancy, and this corresponded with a reduction in hepcidin, HFE, and transferrin receptor 2 expression in the liver. Expression of all molecules returned towards control values by 24-48 hours post-partum.


CONCLUSIONS
These data indicate that increased expression of key iron transport molecules is responsible for the elevated iron absorption associated with pregnancy, and implicate hepcidin, HFE, and transferrin receptor 2 in determining how the maternal iron homeostatic machinery responds to the increased iron demands accompanying gestation.
Millard
K N
KN
Iron Metabolism Laboratory, The Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Brisbane, Queensland 4029 Australia.
Frazer
D M
DM
Wilkins
S J
SJ
Anderson
G J
GJ
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism; D027682:Cation Transport Proteins / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism*; D005260:Female; D000071020:Hemochromatosis Protein; D064451:Hepcidins; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007408:Intestinal Absorption / Q000502:physiology; D007501:Iron / Q000378:metabolism*; D033862:Iron-Binding Proteins / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011990:Receptors, Transferrin / Q000378:metabolism; D000099236:Solute Carrier Family 11, Member 2
D023181:Antimicrobial Cationic Peptides; D027682:Cation Transport Proteins; D000071020:Hemochromatosis Protein; D064451:Hepcidins; D015395:Histocompatibility Antigens Class I; D007501:Iron; D033862:Iron-Binding Proteins; D008565:Membrane Proteins; D011990:Receptors, Transferrin; D000099236:Solute Carrier Family 11, Member 2; C578702:HAMP protein, human; C484232:HFE protein, rat; C578703:Hamp protein, rat; C503640:TFR2 protein, human