Response to delivery stress is not mediated by beta-endorphin (1–31)

ObjectiveThe aim of the study was to determine the reaction of the melanotroph and corticotroph-type pituitary proopiomelanocortin (POMC) response to vaginal delivery and caesarean section stress. Furthermore, the relationship between the release of pituitary POMC fragments, gonadotropins and sexual steroids were examined.Study designBlood samples were obtained from 10 women in labour on arrival in the birth room (tA), at cervix dilatation of 5 cm (tB) and immediately after spontaneous delivery (tC) and in 16 patients undergoing elective caesarean section before induction of anaesthesia (tB) and immediately after delivery (tC). Samples were analysed for cortisol, ACTH, authentic β-endorphin, β-endorphin immunoreactive material (IRM), acetyl-N-β-endorphin IRM (NAC), β-lipotropin (β-LPH) IRM, oestradiol (E2), progesterone (P), prolactin (PRL), FSH and LH.ResultsNAC representing the melanotroph-type pituitary POMC system did not increase during the course of caesarean section or spontaneous labour. In contrast, a significant increase of β-endorphin IRM, β-LPH IRM and ACTH were observed, representing an activation of the corticotroph-type POMC system. Highly significant correlations between POMC fragment concentrations during caesarean section and spontaneous labour were also observed. Sexual steroids (E2 and P) decreased significantly. Except for β-endorphin IRM and E2 in course of spontaneous delivery no significant correlation was observed between POMC fragment and gonadotropins or sexual steroids.ConclusionCaesarean section and spontaneous delivery activated the corticotroph but not the melanotroph POMC system.