Levels of corticotrophin-releasing hormone receptor subtype 1 mRNA in pregnancy and during labour in human myometrium measured by quantitative competitive PCR.

ABSTRACT

It is suggested that corticotrophin-releasing hormone (CRH) is involved in parturition. We have previously reported the presence of the CRH receptor subtype 1 (CRH R1) in human uterine myocytes. The aim of the present study was to investigate whether expression of the CRH R1 in myometrial tissue changes in pregnancy and labour. We used a quantitative competitive PCR method to measure the mRNA levels of this receptor in non-pregnant and in term pregnant myometrium before and at different stages of labour. The levels of mRNA for the housekeeping gene for glucocerebrosidase (GCB) were also determined. The results were expressed as a ratio of CRH R1 and GCB mRNA levels. We have found that in pregnancy the CRH R1 is down-regulated from a ratio of 0.093+/-0.011 in non-pregnant myometrium to 0.012+/-0.005 (P<0.001) in term non-labouring myometrium. No significant changes were observed in the CRH R1GCB ratio in tissues sampled within 13 h (0.013+/-0.004) from the start of labour. In summary, normalised levels of CRH R1 are down-regulated in pregnancy and do not change during labour. We speculate that our results do not support a direct role for the CRH R1 receptor in myometrial stimulation.