Increased Expression of the Rat Myometrial Oxytocin Receptor: DISCUSSION(5)

The patterns of OTR mRNA expression during term and preterm labor, and its regulation by hormonal and mechanical factors, are strikingly similar to those we have previously reported for Cx-43. These data suggest that their transcription is coregulated and support our hypothesis that these two genes contribute to a cassette of genes encoding CAPs that…

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Increased Expression of the Rat Myometrial Oxytocin Receptor: DISCUSSION(3)

Our results clearly demonstrate an important role of mechanical inputs in addition to endocrine factors in the regulation of myometrial OTR expression during parturition. The finding that OTR mRNA level remained low in the nongravid, sham-operated uterine horns during labor indicates that the mere presence of an increased E:P ratio was not sufficient to induce…

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Increased Expression of the Rat Myometrial Oxytocin Receptor: DISCUSSION(2)

Our data also suggest that progesterone is a major negative regulator of OTR mRNA levels in the pregnant rat myometrium. Administration of progesterone blocked both the increase in OTR mRNA levels and labor in rats both at term and following preterm OVX. These results are consistent with data showing that progesterone blocked the increase in…

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Increased Expression of the Rat Myometrial Oxytocin Receptor: RESULTS(3)

These rats had either delivered one or more pups but not completed delivery or had shown signs of impending delivery (vaginal bleeding) at 96 h. The elevation in OTR mRNA levels associated with OVX-induced preterm labor was completely blocked by the administration of progesterone (ROD 0.5 ± 0.1 at both 48 and 96 h). Rats…

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Increased Expression of the Rat Myometrial Oxytocin Receptor: RESULTS(2)

B. Effects of Maintenance of Elevated Progesterone at Term Two-way ANOVA showed an overall significant effect of gestational age on myometrial OTR expression (F = 12.11; df 2,17; p = 0.0013). Control rats receiving injections of vehicle exhibited a 5-fold increase in OTR transcript on Day 23 relative to Day 21 (p < 0.05) (Fig….

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