CORTICOTROPH (BASOPHIL) INVASION OF THE PARS NERVOSA IN THE HUMAN PITUITARY - LOCALIZATION OF PROOPIOMELANOCORTIN PEPTIDES, GALANIN AND PEPTIDYLGLYCINE ALPHA-AMIDATING MONOOXYGENASE-LIKE IMMUNOREACTIVITIES

Corticotroph (basophil) invasion or the migration of corticotroph cell s into the pars nervosa of the human pituitary gland was found in 35 o f 767 (4.4%) consecutive pituitaries obtained at autopsy. The degree o f invasion increased with patient age and extensive invasion was more common in men than in women. Immunoreactive ACTH, beta-MSH, alpha-MSH, and galanin were detected both in the anterior lobe and invading cort icotroph cells in approximately equal frequency. Fewer cells stained p ositively for alpha-MSH than for the three other peptides in both the anterior lobe and invading corticotrophs. Twelve corticotropic pituita ry adenomas obtained surgically from patients with Cushing's disease w ere also examined and expressed varying degrees of immunoreactivity fo r ACTH, alpha MSH, beta-MSH and galanin. Staining for all major pituit ary hormones revealed only ACTH in the invading basophil cells. Peptid ylglycine alpha-amidating monooxygenase (PAM) was present in the anter ior pituitary, in invading corticotroph cells, and in some cells linin g the cysts of the pars intermedia zone. PAM immunoreactivity was also detected in 4/12 corticotroph adenomas. These results indicate that c orticotroph cells invading the pars nervosa are immunohistochemically similar to anterior lobe corticotrophs and have the ability to amidate various peptides such as proopiomelanocortin cleavage products and ga lanin with PAM.