Study for mechanism of retained placenta in cattle

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16580264
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Clinical veterinary science
• Research Institution: Kagoshima University
• Principal Investigator: TAKAGI Mitsuhiro Kagoshima University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (40271746)
• Co-Investigator(Kenkyū-buntansha): IMURA Yoshimi Kagoshima University, Faculty of Agriculture, Assistant Professor, 農学部, 助手 (40336326) ; MIYAMOTO Akio Obihiro University, Faculty of Animal Science, Professor, 畜産学部, 教授 (10192767)
• Project Period (FY): 2004 – 2005
• Keywords: Cattle / Retained placenta / Hormones / MMP / Vasoactive peptide

Research Abstract

The aim of the first study was to evaluate the relationship between the occurrence of retention of the fetal membranes (RFM) and the hormonal concentrations of progesterone, estradiol-17β, prostaglandin E2 (PGE2), prostaglandin F2α (PGF2α), oxytocin (OT), oxytocin receptor (OT-R), endothelin-1 and angiotensin II (Ang II) in the placental tissues of cattle. The placental tissues were collected immediately (0 h) and at 6 h after parturition. The hormonal concentrations were measured by enzyme immunoassay in maternal and fetal placental tissues from RFM, non-RFM and control cows. There were no differences in P4 and E2 concentrations among the RFM, non-RFM and control groups. The mean PGF2α concentration of the RFM group was lower than those of the non-RFM and control groups in the maternal part of the placenta. In maternal tissues, the OT and OT-R concentrations in the RFM group were lower than those at 0 and 6 h after parturition in the non-RFM group. Additionally, the Ang II concentrati on of the RPM group in both the maternal and fetal parts of placental tissues tended to be higher than those of the other groups. In conclusion, the present results suggest that ET-1 and Aug II may play differential tissue-specific roles in the placental unit that may amplify the local endocrinological cascade involving OT, OT-R and PGF2α interactions which are necessary for normal placental separation in the cow.
The aim of the second study was to determine the relationship between mRNA expressions of steroidogenic and proteolytic enzymes in placentomes during gestation and the process of releasing fetal membranes after parturition in cattle. Based on the releasing time of fetal membranes after parturition, the specimens were classified as : 1)the early group, whereby the fetal membranes were released within 6 h after parturition ; and 2)the late group, whereby the fetal membranes were released 6 to 12 h after parturition. Placentomes from a slaughterhouse were additionally examined as samples for the gestation period, whose fetal age was determined as the 1st (0-3 months), 2nd (4-6 months) and 3rd (7-9 months) trimesters by crown rump length. Rather higher mRNA expressions of steroidogenic enzymes in cotyledon than caruncle tissues were observed, and the mRNA expression patterns of P450scc and star tended to be parallel in both placental tissues. On the other hand, although the expression levels of timp-2 mRNA in both caruncle and cotyledon tissues were similar, expression levels of mmp-2 and mmp-9 mRNA were approximately 10 times higher in caruncle than cotyledon tissue during gestation and postpartum. Moreover, marked changes in myna expression patterns between pre- and postpartum periods were observed in mmp-2 and mmp-9 in caruncle tissues and mmp-9 and timp-2 in cotyledon tissues. Our results suggest that the relationship between mRNA expressions of steriodogenic enzymes and mmps/timp-2 may have a critical role in the maintenance of pregnancy and fetal membrane detachment after parturition.