Detection of N-terminal pro-corticotrophin releasing hormone (CRH) and a 'novel' CRH in human maternal plasma and placenta.
Corticotrophin-releasing hormone (CRH) is released from the human placenta in high concentrations towards the end of the third trimester of pregnancy, but relative concentrations of other cleavage products derived from the CRH prohormone are unknown. We have measured CRH and N-terminal (1-100) and (1-127) proCRH peptides in maternal plasma in the second and third trimesters of pregnancy and in term placental extract using immunoradiometric assays (IRMAs) specific to different regions of the CRH precursor. Levels of N-terminal proCRH (amino acid residues 1-100) rose from 24+/-4 pmol/l (mean+/-s.e.) in the second trimester to 378.8+/-65 pmol/l (mean+/-s.e.) at term. Levels of intact proCRH and/or (1-127) proCRH remained relatively constant throughout the second and third trimesters, with a concentration of 29.3+/-3.8 pmol/l (mean+/-s.e.). In the course of this work a novel form of CRH that cross-reacts within specific CRH immunoassays was observed. The use of two IRMAs developed for CRH (1-41) having different C-terminal epitope specificities provided evidence for two types of CRH coexisting in maternal plasma. Separation of term placental extract by HPLC and application of the two CRH IRMAs revealed two peaks of immunoreactivity one of which coeluted with synthetic CRH (1-41).
Sanderson
T C
TC
School of Animal and Microbial Sciences, University of Reading, UK.
Woods
R J
RJ
Kemp
C F
CF
Lowry
P J
PJ
D003346:Corticotropin-Releasing Hormone / Q000097:blood* / Q000276:immunology / Q000378:metabolism*; D003429:Cross Reactions; D005260:Female; D006801:Humans; D015592:Immunoradiometric Assay; D010446:Peptide Fragments / Q000097:blood* / Q000276:immunology / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy / Q000097:blood* / Q000378:metabolism*; D011498:Protein Precursors / Q000097:blood* / Q000276:immunology / Q000378:metabolism*
D010446:Peptide Fragments; D011498:Protein Precursors; C041645:pro-corticotropin releasing hormone; D003346:Corticotropin-Releasing Hormone