Subsets of pituitary intermediate lobe cells bind CRH and secrete ACTH/CLIP in a reverse hemolytic plaque assay

Abstract

Dissociated neurointermediate lobe cells (75%) bound [biotinyl-Ser 1]corticotropin releasing hormone (bio-CRH) and secreted adrenocorticotropin [ACTH(25–39)] in a reverse hemolytic plaque assay (RHPA). The bio-CRH was rapidly internalized (<1 min) in vesicles and scattered vacuoles. Plaque percentages increased from 26±4% to 53±8% after CRH stimulation. Areas increased from 1688 ± 791 μm 2 to 3773 ± 788 μm 2. After AVP treatment for 1 hr, plaque percentages and areas were augmented further. The heterogeneity in secretion may indicate the presence of quiescent IL cells or cells secreting an opiocortin peptide not detected in the plaque assay.