Exp Clin Endocrinol Diabetes 2001; 109(5): 294-301
DOI: 10.1055/s-2001-16350
Articles

© Johann Ambrosius Barth

Investigations on the activity of bovine placental oestrogen sulfotransferase and -sulfatase from midgestation to parturition

B. Hoffmann 1 , K. Falter 1 , A. Vielemeier 1 , K. Failing 2 , G. Schuler 1
  • 1 Klinik für Geburtshilfe, Gynäkologie und Andrologie der Groß- und Kleintiere mit Tierärztlicher Ambulanz, Justus-Liebig-Universität, Giessen, Germany
  • 2 Institut für Veterinär-Physiologie, Arbeitsgruppe Biomathematik und Datenverarbeitung, Justus-Liebig-Universität, Giessen, Germany
Further Information

Publication History

Publication Date:
31 December 2001 (online)

Summary:

To gain further information on the biological role of the high amounts of conjugated estrone (E1S) secreted by the bovine placenta, an in vitro assay system was developed to measure oestrogen sulfotransferase (OST) and oestrogen sulfatase (OS) activities in caruncular and cotyledonary homogenates and the respective subcellular fractions. Placental tissue was obtained from 150 (n = 3), 220 (n = 4), 240 (n = 3) and 270 days (n = 3) pregnant and parturient cows (n = 4). 3H-E1 and 3H-E1S served as substrates and 4-nitrophenyl sulfate potassium salt was used as a competitive inhibitor to block OS when testing for OST activity. OST-activity did not change during pregnancy and parturition and was higher (p < 0.001) in cotyledonary than in caruncular tissue with mean conversions (median) of 61.8% and 41.6% after 30 min of homogenate incubation. On a subcellular level OST-activity was clearly associated with the cytosol. OS-activity was higher (p < 0.001) in caruncular than in cotyledonary homogenates; it was constant during pregnancy (median of conversion: 88.0% and 66.4%, resp.), but was significantly decreased (p < 0.05) at parturition (median of conversion: 48.1% and 30.6%, resp.). On a subcellular level in both the cotyledon and the caruncle highest OS-activities were detected in the microsomal and the mitochondrial fractions. The decreased placentomal OS-activities in parturient cows are inconsistent with a substantial role of OS in the prepartal increase of free oestrogens. These results also suggest that bovine placental oestrogens may largely exert their action locally within the placentomes during most time of gestation as the enzymes catalyzing sulfoconjugation (i.e. inactivation of free estrogens) and desulfation (i.e. activation of conjugated oestrogens) are expressed in close proximity to each other. In this respect the finding of oestrogen receptors in caruncular stromal cells is of particular interest.

References

Prof. Dr. Bernd Hoffmann

Klinik für Geburtshilfe

Gynäkologie und Andrologie der Groß- und Kleintiere

mit Tierärztlicher Ambulanz der Justus-Liebig-Universität Giessen

Frankfurter Str. 106

D-35392 Giessen

Germany

Phone: +49-641-99-38704

Fax: +49-641-29328

Email: bernd.hoffmann@vetmed.uni-giessen.de

    >