Effect of oxytocin on concentration of PGF(2α) in the uterine lumen and subsequent endometrial responsiveness to oxytocin in pigs

K. G. Carnahan, B. C. Prince, T. E. Ludwig, M. Uzumcu, M. A. Evans, M. A. Mirando

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11 Scopus citations

Abstract

The aim of this study was to determine the effect of oxytocin on PGF(2α) secretion into the uterine lumen of pigs and subsequent endometrial responsiveness to oxytocin in vitro. Cyclic, pregnant and oestradiol-induced pseudopregnant gilts were injected i.v. with vehicle or 20 iu oxytocin 10 min before hysterectomy on day 16 after oestrus. Concentrations of PGF(2α) and 13,14-dihydro-15-keto PGF(2α) (PGFM) were significantly increased in uterine flushings collected at hysterectomy (P < 0.05) in pregnant oxytocin-injected gilts. Concentrations of PGF(2α) and PGFM were greater (P < 0.001) in pregnant than in pseudopregnant and cyclic gilts, and greater (P < 0.01) in pseudopregnant than in cyclic gilts. The ratio of PGFM:PGF(2α) tended to be greater in cyclic (P < 0.06) and pseudopregnant gilts (p < 0.1) than in pregnant gilts. At 85 ± 5 min after oxytocin injection, endometrium from each gilt was incubated for 3 h for determination of phosphoinositide hydrolysis and PGF(2α) secretion in response to treatment with 0 or 100 nmol oxytocin l-1. Endometrial phosphoinositide hydrolysis in response to 100 nmol oxytocin l-1 in vitro was greater (P < 0.05) in cyclic oxytocin-injected gilts than in cyclic vehicle-injected gilts. Treatment with oxytocin in vitro did not stimulate phosphoinositide hydrolysis significantly in vehicle- or oxytocin-injected pregnant gilts or pseudopregnant gilts. Endometrial PGF(2α) secretion increased after treatment with 100 nmol oxytocin l-1 in vitro in cyclic vehicle-injected (P < 0.01), cyclic oxytocin-injected (p < 0.01), pregnant vehicle-injected (P = 0.06), pseudopregnant vehicle-injected (P < 0.05) and pseudopregnant oxcytocin-injected (P < 0.05) gilts, but not in pregnant oxytocin-injected gilts. The increase in PGF(2α) in pseudopregnant oxytocin-injected gilts was less (P < 0.05) than that in cyclic oxytocin-injected gilts. These results indicate that oxytocin increases the concentration of PGF(2α) and PGFM in the uterine lumen during pregnancy and may upregulate endometrial responsiveness to oxytocin during late dioestrus in pigs, but does not have the latter effect during early pregnancy or oestradiol-induced pseudopregnancy.

Original languageEnglish (US)
Pages (from-to)207-212
Number of pages6
JournalJournal of Reproduction and Fertility
Volume117
Issue number2
StatePublished - Nov 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Embryology
  • Molecular Biology
  • Obstetrics and Gynecology
  • Developmental Biology

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