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

Objective To determine whether corticotrophin releasing hormone plays a rol e 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 u nder regional anaesthesia. Methods Human corticotrophin releasing hormone (1, 10, 100 nmol/L) was adde d to strips of term, nonlabouring myometrium mounted in an organ bath, and the effect on spontaneous, oxytocin (1 nmol/L) or prostaglandin F-2 alpha ( 100 nmol/L) stimulated contractions determined. Cyclic adenosine monophosph ate (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 transientl y 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 concentra tions of corticotrophin releasing hormone in pregnancy at term, this peptid e is unlikely to play a direct role in the control of myometrial contractil ity in nonlabouring myometrium.