Differential processing of corticotrophin-releasing hormone by the human placenta and hypothalamus

The molecular forms of corticotrophin-releasing hormone (CRH) in human placentae and hypothalami were investigated by gel permeation chromatography of water extracts. Hypothalamic extracts produced one peak of immunoreactivity which coeluted with human CRH at Kd = 0.53. Placental extracts, however, had in addition to that peak, two other peaks eluting earlier at the void and at Kd = 0.35-0.38. Tryptic digestion of the middle peak produced immunoreactivity which coeluted with the standard. Larger forms were also found in plasma of women in the third trimester of pregnancy and during labour but not in eluates from superfused placental fragments which had only CRH41-sized material. These data indicate that tissue-specific post-translational processing occurs for CRH, and suggests that the link between synthesis and secretion is more immediate in the placenta than hypothalamus.