Bovine Retained Placenta: Expression of Pro- and Anti-Apoptotic Factors in Fetal and Maternal Placenta.

Abstract

Retention of fetal membranes (RFM) is normally defined as the condition in which the fetal membranes are not expelled from the uterus within a period of 12 h after expulsion of the fetus. RFM is economically one of the most important disturbances during the postpartum period in cattle, because it affects herd health, milk production and reproductive efficiency. Recent studies demonstrated that apoptosis induced decidual regression and separation from the endometrium in human and rodents. In previous study, we showed that the levels of CASP3 mRNA expression were higher in maternal placental tissue (caruncula) of RFM cows than those of non-RFM cows (P < 0.05). The above findings suggest that apoptosis of fetal membranes are crucial for the normal separation and expulsion of the placenta after parturition. The present study examined the expressions of pro-apoptotic factors (BAX, FAS, CASP8) and anti-apoptotic factors (BCL2, CFLAR) in cows with and without RFM. The placentomes were manually collected from the uterus via intra vaginal immediately after parturition (0 h). Samples were classified retrospectively into two groups (RFM (n=5) and non-RFM (n=5)) according to whether placental membranes were expelled or not within 12 h after delivery. Fetal and maternal membranes of placenta were manually separated. Real time RT-PCR analysis of fetal and maternal placenta revealed that FAS mRNA expression were lower in maternal placental tissue (caruncula) of RFM cows than those of non-RFM cows (P < 0.05). The levels of CFLAR mRNA expression, anti-apoptotic factor, were lower in both maternal and fetal placental tissue of RFM cows than those of non-RFM cows (P < 0.05). However, the protein expressions of FAS and CFLAR examined by western blotting was not significantly different between RFM and non-RFM groups. The expression of other apoptotic factors analyzed in fetal and maternal placenta were not significantly different between RFM and non-RFM cows. The overall results suggest that apoptosis are necessary for normal placental separation in cows and that RFM occurs at least in part due to a dysfunctional apoptotic process in the maternal placenta tissue. The different expressions of mRNA and protein may be due to the fact that placental tissues were collected immediately after parturition. Further temporal studies are in progress to clarify the expression of pro- and anti-apoptotic factors in placentomes. (poster)