Vascular expression of adrenomedullin is increased in Wistar rats during early pregnancy.
OBJECTIVE
Circulating levels of adrenomedullin (ADM)--a vasodilator peptide with long-lasting effects--increase in the course of pregnancy. Neither the site nor the concomitant rate of ADM synthesis in pregnancy is known. The aim of this study was to test the hypothesis that the rise in plasma levels of ADM during pregnancy is paralleled by increased gene expression and protein levels in the vascular bed.


METHODS
We determined in cardiovascular and reproductive tissues of non-pregnant (n=10) and 10-days pregnant (n=10) Wistar rats ADM gene expression by semi-quantitative RT-PCR (normalized to GAPDH). As a support for the mRNA data, protein concentrations were measured by both ELISA and Western blot analysis. Finally, ADM in these tissues was localized by immunohistochemical staining. Statistical analysis was carried out by applying Mann-Whitney U-test.


RESULTS
ADM mRNA levels in the abdominal aorta, renal artery and the kidney were increased during pregnancy. In addition, immunohistochemical staining in the kidney, uterus, abdominal aorta, renal, uterine and superior mesenteric artery was more intense as compared to non-pregnant rats. However, we observed lower concentrations of tissue ADM protein in pregnant rats, indicating an increased release of the hormone by the producing cells.


CONCLUSIONS
Vascular ADM gene expression is increased in the first half of rat pregnancy. This coincides and may be functionally related to the institution of a high flow/low resistance circulation in pregnancy.
van der Heijden
Olivier W H
OW
Department of Obstetrics and Gynecology, Research Institute Growth and Development (GROW), University Hospital Maastricht-AZM, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Essers
Yvonne P G
YP
van Eyndhoven
Hugo W F
HW
Spaanderman
Marc E A
ME
Aardenburg
Robert
R
van Eys
Guillaume J J M
GJ
Peeters
Louis L H
LL
D053607:Adrenomedullin; D000818:Animals; D001012:Aorta, Abdominal / Q000378:metabolism; D001808:Blood Vessels / Q000378:metabolism*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007668:Kidney / Q000378:metabolism; D017538:Mesenteric Artery, Superior / Q000378:metabolism; D010455:Peptides / Q000235:genetics* / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012077:Renal Artery / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000378:metabolism
D010455:Peptides; D053607:Adrenomedullin