Effects of LPS and IL-6 on oxytocin receptor in non-pregnant and pregnant rat uterus

PROBLEM: Little is known regarding the regulation of the timing of parturit ion. Recent evidence suggests an interaction between the immune system and uterine contractility in late gestation. METHOD: Pregnant rats were treated with LPS in vivo in attempts to establis h a model of premature parturition induced by the pro-inflammatory response . Uterine explants were incubated in vitro to determine the effects of IL-6 on uterine synthesis of oxytocin (OT) and its receptor (OTR). RESULTS: LPS injection was quite toxic to pregnant rats and gave extremely variable results. In animals that delivered, there was a marked increase in the uterine concentrations of OTR and OTR mRNA. There was no consistent ef fect regarding the timing of parturition. IL-6 caused a significant increas e in the concentration of OTR mRNA in uterine explants from pregnant rats b ut not in tissues from non-pregnant animals. CONCLUSION: Rat uterine concentrations of OTR are regulated by IL-6. Pro-in flammatory cytokines may stimulate uterine contractility in late gestation rat uterine tissues through a mechanism involving stimulation of OTR.