Adrenomedullin Antagonist Treatment During Early Gestation in Rats Causes Fetoplacental Growth Restriction Through Apoptosis1

Abstract

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.

Trophoblast Invasion and Uterioimplantation Growth in Early Rat Gestation Requisite Adrenomedullin

“…Several reports of previous studies displayed that there was a significant decrease in fetal and placental growth in pregnant rats when ADM was continuously infused from day 14 of gestation and several days after implantation and placental formation (Witlin et al, 2002 andPenchalaneni et al, 2004). Increase in fetal resorptions was not only observed in previous studies but also displayed in the current study.…”

“…The minipumps were filled with saline alone or with saline containing different concentrations of AM . These concentrations were chosen based on the earlier findings of Witlin et al [26] and Penchalaneni et al [25] to deliver AM at 125 and 250 µg/rat/day.…”

Adrenomedullin Antagonist Infusion Causes Uteroimplantation Growth Restriction

“…The six -membered amino acid ring structure connected by one disulfide bond between (between cys16 and cys21) along with receptor modifying protein (RAMP) was found to be responsible for vasodilator activity in human ADM as shown in Figure- vascularization, and increased fetal resorption, in the rat. [10][11] In the present study, the ADM- They elevate cAMP generation in platelets. CGRP is a 37 amino acid neuropeptide, Calcitonin is a 32 amino acid peptide, Amylin is a 37 amino acid peptide.…”

Plasma Adrenomedullin Levels during Multiple Pregnancy

“…In addition, treatment of pregnant rats with an antagonist of AM function caused fetal growth restriction and decreased placental size [12,13] . These data suggest that AM is a vital endogenous vasodilatator peptide responsible for fetal development and maintenance of normal placental function during gestation.…”