Effects of prostaglandins and oestradiol-17b on oxytocin binding in cultured bovine luteal cells

Kiyoshi Okuda, Yoshihisa Uenoyama, Akio Miyamoto, Akira Okano, Florian J. Schweigert, Dieter Schams

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The aim of the investigation was to evaluate the possible action of prostaglandins (PGs) and oestradiol-17b (oestradiol) on the specific binding for oxytocin in bovine luteal cells. Cultured cells of bovine corpora lutea at the mid-luteal stage (Day 8-12 of the oestrous cycle) were examined for the presence of oxytocin receptors by a radioreceptor assay using the 125l-labelled oxytocin antagonist [d(CH2)s, Tyr(Me)2, Thr4, Tyr-NH29]-vasotocin (125I-OVT) as a ligand. The cells were cultured for 48 h in total. In the final 15 h of culture, the luteal cells were exposed to varying concentrations of PGF20 PGE2, PGI2 and/or oestradiol. After culture, the cells were incubated with 37000 dpm (0-5 nM) 125I-OVT with or without 100 nM of unlabelled oxytocin. PGF2a, at 10-8 M and 10-7 m, stimulated the specific binding for oxytocin to levels as high as 128% of controls (P<001); by contrast, PGE2, PGI2 or oestradiol had no effect on oxytocin binding. Scatchard analysis revealed that the concentration of oxytocin receptors was increased (P< 0 05) from 6-7fmol mg-1 DNA to 8-4fmol mg-1 DNA by stimulation with 10-7 M of PGF2, without changing the binding affinity. No further increase in the specific binding was observed when PGF2a was used in combination with PGE2, PGI2 or oestradiol at a concentration of KT7 m. Addition of indomethacin (28 mm) resulted in the inhibition of PGF^ secretion, coinciding with a significant decrease in oxytocin binding (P<0 01). However, addition of arachidonic acid (100 p.m) caused a significant increase in the secretion of PGF2a and the specific binding for oxytocin concomitantly (P < 0.05). When the protein kinase C (PKC) activity of the luteal cells was inactivated by preincubating cells for 13 h with 1 mM phorbol 12-myristate 13-acetate before PGF2a stimulation, the specific binding for oxytocin was not affected by PGFoa stimulation (10-7 m) in the final 15 h of culture. These data suggest that PGF2a may be one of the potent regulators for luteal oxytocin receptors in a paracrine and/or autocrine manner, and that its action is mediated by PKC.

Original languageEnglish
Pages (from-to)1045-1051
Number of pages7
JournalReproduction, Fertility and Development
Volume7
Issue number5
DOIs
Publication statusPublished - Jan 1 1995

Keywords

  • Corpus luteum
  • Oxytocin receptor
  • Prostaglandin F2a

ASJC Scopus subject areas

  • Biotechnology
  • Reproductive Medicine
  • Animal Science and Zoology
  • Molecular Biology
  • Genetics
  • Endocrinology
  • Developmental Biology

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