Detection of corticotropin-releasing hormone receptors R1 and R2 (CRH-R1, CRH-R2) using fluorescence immunohistochemistry in the myometrium of women delivering preterm or at term.

OBJECTIVE

To determine differences in expression of corticotropin-releasing hormone receptors R1 and R2 in the myometrium of women delivering preterm or at term, with or without labor.

MATERIAL AND

METHODS

Small pieces of myometrial smooth muscle were taken from forty patients undergoing caesarian section. One sample each was taken from all preterm and term patients, with and without labor. Antibodies against CRH-R1/2 and CRH-R2 were used for localization by conventional fluorescence immunohistochemistry. The evaluation of staining was based on examination of the entire histologic section by three independent observers.

RESULTS

In women at term, CRH-R2 levels were elevated before labor and decreased with the onset of labor. In eight of 10 term samples from women in labor, no staining was detected. In preterm patients we found no difference in CRH-R2 staining between women with and without labor. The intensity of staining for CRH-R1/2 was generally uniform in all four groups.

CONCLUSION

The high level of CRH-R2 expression in term patients without labor, together with the subsequent decrease of CRH-R2 in the myometrium during progression of labor, is consistent with the possibility that CRH may have autocrine/paracrine effects on myometrial contractility in the lower segment of the uterus.