IMMUNOLOCALIZATION OF EICOSANOID ENZYMES AND GROWTH-FACTORS IN HUMAN MYOMETRIUM AND FETOPLACENTAL TISSUES IN FAILED LABOR INDUCTIONS

Objective: To investigate the correlation between myometrial-derived e icosanoids and growth factors during the onset of parturition. Methods : Myometrial samples were obtained from patients who were delivered by cesarean for failed induction or abnormal fetal heart rate tracings b ut who experienced normal labor progression until the occurrence of th e abnormal tracing. placentas and fetal membranes were obtained from p atients with normal labor, no labor, and failed labor progression. The tissues were processed and sections were immunostained for cyclooxyge nases, prostacyclin synthetase (PGI(2)-S), thromboxane A, synthetase ( TXA(2)-S), 5-lipoxygenase, epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and EGF receptor, using specific ant ibodies directed against these molecules. Results: Myometrial and feto placental tissues from women with normal labor, no labor, and failed l abor contain immunoreactive cyclooxygenases, 5-lipoxygenase, TXA(2)-S, PGI(2)-S, EGF, TGF-alpha, and EGF receptor. However, their immunostai ning intensity, with the exception of EGF receptor, decreased substant ially in myometrium from women with failed labor induction compared wi th those having normal labor progression No difference was noted in th e immunostaining intensity of growth factors and eicosanoid enzymes in the fetoplacental membranes from these patients, except for cyclooxyg enases, which were prominent in fetal membranes from normal labor comp ared with failed labor and no labor. Conclusion: Myometrial-derived ei cosanoids and growth factors may be important in processes of parturit ion because reduction in their production in the myometrium is correla ted with failed labor induction. Because of the regulatory action of g rowth factors in eicosanoid biosynthesis in uterine and fetoplacental tissues, EGF/TGF-alpha may indirectly influence the process of parturi tion by regulating eicosanoid production in the myometrium.