Adrenomedullin antagonist treatment during early gestation in rats causes fetoplacental growth restriction through apoptosis.
Adrenomedullin (AM), a potent vasorelaxant peptide, has been shown to function as an angiogenic and growth factor. The present study investigated whether antagonism of endogenous AM in rats during early gestation results in diminished placental and fetal growth and whether this occurs through induction of apoptosis. Rats on Gestational Day 8 were implanted s.c. with osmotic minipumps delivering 125 and 250 microg rat(-1) day(-1) of AM(22-52) and were killed on Gestational Day 15. In AM(22-52)-treated rats, both placental and fetal weights were dose-dependently inhibited, with 50% reduction in the group receiving 250 microg rat(-1) day(-1). In these animals, fetal resorption sites were also increased. Apoptosis was demonstrated in placenta and uterus by the TUNEL method. Apoptotic changes were more apparent in trophoblast cells in the labyrinth zone of placenta and uterine decidua of AM(22-52)-treated rats when compared with vehicle-control rats. Immunoreactivity to active caspase-3 protein was abundant in the placenta and uterus of the AM(22-52)-treated group. Western blot analysis demonstrated that in homogenates of both the placenta and uterus of AM(22-52)-treated rats, levels of active caspase-9 and -3 as well as of Poly ADP ribose polymerase were significantly increased, whereas levels of Bcl-2 protein decreased, compared with controls. However, no significant treatment-associated changes were observed in Bid, Fas, Fas ligand, p53, and caspase-8 and -10 proteins in either placenta or uterus. Bad protein was undetectable in either tissue. In mitochondrial fractions from both placenta and uterus, the levels of Bax increased with decreases in cytochrome c on AM(22-52) treatment. Conversely, in the cytosol, Bax levels decreased with increases in cytochrome c, demonstrating translocation of Bax from cytosol to mitochondria and release of cytochrome c from mitochondria with AM(22-52) treatment. In conclusion, these findings show that antagonism of AM in rats during early pregnancy caused fetoplacental growth restriction through the activation of mitochondrial apoptotic pathways.
Penchalaneni
Josthna
J
Department of Obstetrics and Gynecology, University of Texas Medical Branch, 301 University Blvd., Galveston, Texas 77555, USA.
Wimalawansa
Sunil J
SJ
Yallampalli
Chandrasekhar
C
D053607:Adrenomedullin; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D020169:Caspases / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D053222:Fas Ligand Protein; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005317:Fetal Growth Retardation / Q000139:chemically induced / Q000503:physiopathology; D005327:Fetal Resorption; D020567:Fetal Weight / Q000187:drug effects; D005865:Gestational Age; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000037:antagonists & inhibitors* / Q000502:physiology*; D010920:Placenta / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D010929:Placentation; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014599:Uterus / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; C104782:adrenomedullin (22-52); D019014:fas Receptor; D053607:Adrenomedullin; D045304:Cytochromes c; D019001:Nitric Oxide Synthase; D020169:Caspases