Response of proopiomelanocortin and gonado- or lactotroph systems to in-vitro fertilisation procedures stress

Objective

To analyse for the first time the response of the corticotroph-type and the melanotroph-type pituitary proopiomelanocortin (POMC) system with regard to in-vitro fertilisation (IVF) treatment using self-developed highly specific non-cross-reacting radioimmunoassay.

Study design

Setting: University hospital. Patients: A total of 28 patients undergoing IVF oocyte retrieval. Cross sectional exploratory study, one factorial design with repeated measurements on one factor, non-parametric tests. Blood was collected before anaesthesia (t_A) (n = 28) and immediately after oocyte retrieval (t_B) (n = 28). Main outcome measure(s): β-endorphin immunoreactive material (IRM), acetyl-N-β-endorphin IRM, β-lipotropin IRM, ACTH, cortisol, estradiol, progesterone, prolactin, luteinizing hormone, and follicle-stimulating hormone. For determination of authentic β-endorphin [β-endorphin (1–31)] a highly specific two-site fluid phase immunoprecipitation radioimmunoassay was developed, which did not cross-react with any β-endorphin derivative or any other opioid peptide tested.

Results

No response of acetyl-N-β-endorphin IRM and of authentic β-endorphin (1–31) was observed to oocyte retrieval in contrast to a significant increase of corticotroph-type proopiomelanocortin derivatives. A significant rise in prolactin plasma concentration indicates a pronounced lactotroph response to oocyte retrieval stress. No significant correlation between POMC derivates and prolactin and between POMC derivatives and gonadotropins or sexual steroids except for ACTH and progesterone and for β-endorphin IRM and estradiol was observed.

Conclusion

IVF treatment stress led to significant corticotroph-type POMC and lactotroph responses, but not to responses of authentic β-endorphin or melanotroph-type POMC in women undergoing oocyte retrieval.