Effects of corticotrophin releasing hormone on contractile activity of myometrium from pregnant women

OBJECTIVE: To determine whether corticotrophin releasing hormone plays a role in the regulation of tone in term nonlabouring human myometrium. SETTING: A teaching hospital research laboratory. SAMPLE: Thirty-seven women undergoing elective nonlabour caesarean section under regional anaesthesia. METHODS: Human corticotrophin releasing hormone (1, 10, 100 nmol/L) was added to strips of term, nonlabouring myometrium mounted in an organ bath, and the effect on spontaneous, oxytocin (1 nmol/L) or prostaglandin F2alpha (100 nmol/L) stimulated contractions determined. Cyclic adenosine monophosphate (cAMP) content of the tissue was also determined by enzyme immunoassay. RESULTS: Corticotrophin releasing hormone did not affect myometrial tension development in any of the experimental protocols. cAMP increased transiently after addition of corticotrophin releasing hormone (166.7 +/- 12.7% at 1 minute) but this was not reflected by any change in tension. CONCLUSIONS: This study suggests that despite high maternal plasma concentrations of corticotrophin releasing hormone in pregnancy at term, this peptide is unlikely to play a direct role in the control of myometrial contractility in nonlabouring myometrium.