Immunolocalization Of Glucocorticoids Receptor, 11 Beta-hydroxysteroid Dehydrogenase1 And 2 In The Cervices Of Peripartal Mice

Proper cervical softening is essential for a normal birth to occur. It is not a passive process of secondary to uterine contractions, but an active, energy consuming, inflammatory cells infiltrating process, which is also correlated with inflammatory mediators. Various hormones and inflammatory mediators play a physiological function for cervical ripening and softening through direct or indirect regulation of cervical histological, biochemical and morphological changes. The effects of glucocorticoid and glucocorticoid receptor have attracted a lot of attention, but its mechanism remains obscure. The purpose of this study was to conduct a preliminary interpretation on this mechanism. Glucocorticoids are steroid hormones which were synthesized in the zona fasciculata of the adrenal cortex, and play an important role in the process of body’s metabolism and stress reaction. Glucocorticoids exert their biological effects through binding to its receptor, and the expression of the glucocorticoid receptor in target tissues determines the sensitivity of target tissues to glucocorticoids to a certain extent. It is now well established that glucocorticoid actions in several target tissues are dependent not only on the expression of the glucocorticoid receptor(GR), but also on the 11beta--hydroxysteroid dehydrogenase(11βHSD) enzymes, two distinct isoforms, which catalyse the activation or inactivation of glucocorticoids respectively, regulating local intracellular glucocorticoid concentrations together.Glucocorticoids are important hormones involved in childbirth, and exert their biological effects through binding to its receptor, but its regulatory mechanisms for cervical ripening expansion are not yet clear. The present study was designed to gain insight into the role of glucocorticoid(GC), glucocorticoids receptor(GR), and 11beta-hydroxysteroid dehydrogenase(11βHSD) enzymes in the cervical dilation of peripartal mice. Mice in five groups were from 48 h before birth(-48 h) and-24 h, at term labor(0 h), 12 h after birth(+12 h) and +48 h. The dynamic change of the serum corticosterone level was determined by ELISA; the specificity of the different anti-human polyclonal antibodies for murine NR3C1 receptor protein, 11βHSD-1 and 2 in peripartum murine cervices was assayed by Western blot analysis; immunolocalization of GR, 11βHSD-1 and 2 which influence glucocorticoid’s activity in cervix was assayed by immunohistochemistry. The results suggested that the levels of serum corticosterone were significantly increased before the onset of labor, reached the maximum during delivery(P <0.01). We observed a dim protein band of 86 k Da by staining with the anti-NR3C1 antibody, a 35 k Da band with the anti-11βHSD-1 antibody, and a 44 k Da band with the anti-11βHSD-2 antibody. In addition, the GR, 11βHSD-1 and 2 protein were localized to the nuclei of cervical luminal epithelia, stromal cells, vascular and cervical smooth muscles. The quotient between mean optical density of 11βHSD-1 and 2 is highest at parturition. Furthermore, the immunoreaction of GR also reached the peak at parturition(P <0.01).These results support hypotheses that 11βHSD-1-regenerated cortisol and its receptor increased greatly to regulate the muscular functions cervical ripening and dilation during parturition. The glucocorticoid levels of inperipheral blood and uterine cervical tissue decreased as wll as the expression of glucocorticoid receptor after the birth, and the cervical morphology restored. Therefore 11βHSD-1-regenerated glucocorticoids may actviaits receptor to play an important role in the final cervical ripening.