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Low sensitivity to oestrogens in bovine placenta at term
Zentralblatt Fur Veterinarmedizin. Reihe A
|March 1, 1989
Summary
Elevated oestrogen levels at term in cows appear to have minimal impact on placental maturation. Research indicates low oestrogen receptor levels in bovine placental tissue, suggesting limited physiological importance.
Area of Science:
- Reproductive biology
- Endocrinology
- Veterinary medicine
Background:
- Oestrogen levels rise significantly in cattle nearing parturition.
- The role of these elevated oestrogens in bovine placental maturation remains unclear.
- Understanding placental sensitivity to hormones is crucial for reproductive success.
Purpose of the Study:
- To investigate the sensitivity of bovine placental tissue to oestrogens.
- To quantify oestrogen receptor levels in the maternal and fetal compartments of the placenta.
- To determine the physiological importance of oestrogens for placental maturation.
Main Methods:
- Estimation of oestrogen receptor levels in mature bovine placental tissue.
- Utilized heparin sepharose chromatography for receptor binding and washing.
- Quantified receptor levels via incubation with 3H-oestradiol and removal of unbound steroids.
Main Results:
- Low oestrogen receptor levels (5-14 fmol/mg protein) were detected in the maternal placental compartment.
- The fetal compartment showed negligible oestrogen receptor levels (less than 1 fmol/mg).
- Bovine placental tissue exhibits low sensitivity to oestrogens.
Conclusions:
- Unconjugated oestrogens likely play a minor role in bovine placental maturation due to low receptor levels.
- The pre-parturition oestrogen peak may serve as a maturation marker but has questionable physiological significance for the placentome.