01 Jan

Endometrial Responsiveness to Oxytocin: DISCUSSION(3)

The suggestion that endometrial responsiveness to ОТ is not regulated primarily through changes in expression of OTr is supported further by comparison of results for cyclic and pregnant gilts in experiments 1 and 2. Responsiveness to ОТ occurred primarily in cyclic gilts on Day 16, and, to a lesser extent, in pregnant gilts on Day 12. Sensitivity to ОТ was also attenuated on Day 16 of pregnancy compared to that in cyclic gilts. Although these changes in responsiveness to ОТ were associated with modest alterations in OTr population density, they did not approach the dramatic changes in OTr numbers that occurred during luteolysis and early pregnancy in ruminants. Additionally, increased responsiveness to ОТ in cyclic gilts on Day 16 was also associated with increased affinity of OTr.

Finally, abundance of OTr mRNA did not change in cyclic gilts between Days 12 and 15 in experiment 2, when responsiveness to ОТ was developing in experiment 1. Message for OTr also was not reduced during pregnancy and, in fact, was increased on Days 10-15 compared with endometrium from cyclic gilts. This latter observation conflicts with the reduced endometrial responsiveness to ОТ during early pregnancy reported for previous studies and observed in experiment 1, but it is consistent with the previous suggestion that responsiveness to ОТ is not regulated solely through changes in expression of OTr in swine. It also indicates that the increased ОТ mRNA present during early pregnancy in swine may not be translated into functional OTr protein.

Categories: Early Pregnancy
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