Expressions of apoptosis-regulating factors in bovine retained placenta

The aim of the present study was to evaluate the relationship between the retention of fetal membranes (RFM) and apoptosis of the cells in fetal membranes. The present study investigated mRNA and protein expressions of apoptosis-regulating factors: FAS, cellular FLICE-like inhibiting protein (cFLIP), BAX, BCL2, caspase-8 (CASP8), and CASP3 in fetal membranes. Placentomes were manually collected from the uterus immediately after parturition and classified into two groups (RFM; n = 8 and non-RFM; n = 8) according to whether placental membranes were expelled or not within 12 h after delivery. FAS mRNA expression in maternal placental tissue was less in RFM cows than in non-RFM cows (P < 0.05). cFLIP mRNA expression in maternal and fetal placental tissue was greater in RFM cows than in non-RFM cows (P < 0.05). CASP3 mRNA expression in maternal placental tissue was greater in RFM cows than in non-RFM cows (P < 0.05). However, the protein expressions of FAS, cFLIP and cleaved CASP3 were not significantly different between the two groups. mRNA and protein expressions of BAX, BCL2 and CASP8 were also not significantly different between the two groups. In the immunohistochemical study, single-stranded DNA, which appears specifically in the apoptotic cells, was mainly found in the maternal placenta of non-RFM cows. Together these results suggest that RFM occurs at least in part due to a dysfunctional apoptotic process caused by the inhibition of FAS expression in the maternal placenta, and the increase of cFLIP expression in the maternal and fetal placenta.