Expression of Glucocorticoid Receptor in Human Myometrium during Pregnancy and Labour

Inflammatory events have been implicated in the process of labour. Glucocorticoids mediate strong antiinflammatory effects through binding to the glucocorticoid receptor (GR), which on activation translocates to the nucleus and increases or decreases the expression of responsive genes thereby suppressing inflammation. We characterised the expression profile of GR protein and mRNA in human non-pregnant (n=10), term pregnant non-labouring (n=10) and labouring (n=10) myometrium, as well as in first trimester, second trimester and preterm labouring myometrium (n=5-10), by Western blotting, immunofluorescent staining, and RT-PCR. GR-? and GR-? protein were detected in all samples. Compared to non-pregnant myometrium, levels of both isoforms were lower in pregnant myometrium (p<0.05 for GR-?, p<0.01 for GR-?). No differences were found between labouring vs. non-labouring and upper vs. lower segment myometrium. While immunofluorescent staining for GR was predominantly nuclear in non-pregnant myometrium, staining was more evenly distributed across the nuclei and cytoplasmic compartments in term pregnant samples. Compared to non-pregnant and term pregnant myometrium, levels of GR-? mRNA were lower in term labouring myometrium (p<0.001 ad p<0.01 respectively). In contrast, GR-? mRNA was only detected in a small number of myometrial samples. It is possible that the observed alterations in GR expression may contribute to the sequence of inflammatory events implicated in parturition.