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 eicosanoids 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 but who experienced normal labor progression until the occurrence of the abnormal tracing. Placentas and fetal membranes were obtained from patients with normal labor, no labor, and failed labor progression. The tissues were processed and sections were immunostained for cyclooxygenases, prostacyclin synthetase (PGI2-S), thromboxane A2 synthetase (TXA2-S), 5-lipoxygenase, epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and EGF receptor, using specific antibodies directed against these molecules.

RESULTS

Myometrial and fetoplacental tissues from women with normal labor, no labor, and failed labor contain immunoreactive cyclooxygenases, 5-lipoxygenase, TXA2-S, PGI2-S, EGF, TGF-alpha, and EGF receptor. However, their immunostaining intensity, with the exception of EGF receptor, decreased substantially in myometrium from women with failed labor induction compared with those having normal labor progression. No difference was noted in the immunostaining intensity of growth factors and eicosanoid enzymes in the fetoplacental membranes from these patients, except for cyclooxygenases, which were prominent in fetal membranes from normal labor compared with failed labor and no labor.

CONCLUSION

Myometrial-derived eicosanoids and growth factors may be important in processes of parturition because reduction in their production in the myometrium is correlated with failed labor induction. Because of the regulatory action of growth factors in eicosanoid biosynthesis in uterine and fetoplacental tissues, EGF/TGF-alpha may indirectly influence the process of parturition by regulating eicosanoid production in the myometrium.