Corticotropin releasing hormone- and adreno-corticotropin-like immunoreactivity in human placenta, peripheral and uterine vein plasma.

The presence of corticotropin releasing hormone (CRH)-like immunoreactivity (IR) in human placenta and maternal peripheral blood has been reported by many investigators. However, its physiological role has not yet been defined. We investigated plasma and placental tissue from women at different times of pregnancy and performed peripheral and uterine vein sampling during caesarean section before and after removal of the placenta. Beside IR-CRH, IR-GRF and -GnRH as well as -ACTH and cortisol were measured. The highest content of CRH was found in placental extracts from end term (40 weeks) pregnancies and lower levels at an earlier stage (10 weeks). Plasma CRH from peripheral blood could be detected in some samples and was higher as pregnancy advanced. Thirty minutes after removal of the placenta CRH levels dropped in peripheral plasma and could not be detected in uterine vein samples. IR-ACTH plasma levels were within the range of normals, cortisol was elevated. Gel- and HPLC-chromatographie revealed that placental extracts coeluted with synthetic human CRH. The material from endterm placenta showed full bioactivity in the rat pituitary bio-assay. IR-GRF could only be detected in 10 weeks placental tissue and no IR-GnRH was measured. We conclude that CRH from the placenta is biologically active, however, cannot stimulate the maternal pituitary-adrenal-axis.