The immunolocalization of ACTH and alpha MSH in human and rat pituitaries.
Human and rat pituitaries were investigated immunohistochemically for ACTH and alpha MSH activity by means of the enzyme-labeling technique. In rat pituitaries cells present in both the anterior and intermediate lobes were reactive with the anti-ACTH antibodies, the cells from the intermediate lobe were also reactive with anti-alpha MSH antibodies. In human pituitaries, ACTH-immunoreactivity was found in cells from the anterior lobe and cells invading the posterior lobe. In 5 out of 15 pituitaries ACTH-immunoreactive cells located at or invading the posterior lobe were also reactive with the anti-alpha MSH antibodies. It is concluded that the human pituitary cells that invade the posterior lobe represent a population which is at least immunohistochemically identical with the intermediate lobe cells of the rat. The ACTH-immunoreactivity of intermediate lobe cells may be explained by the presence of a corticotropin-like intermediate lobe peptide (CLIP) which has been suggested to be a prohormonal fragment of alpha MSH.
D000324:Adrenocorticotropic Hormone / Q000032:analysis*; D000818:Animals; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000032:analysis*; D010902:Pituitary Gland / Q000032:analysis*; D010903:Pituitary Gland, Anterior / Q000032:analysis; D010904:Pituitary Gland, Posterior / Q000032:analysis; D051381:Rats
D000324:Adrenocorticotropic Hormone; D009074:Melanocyte-Stimulating Hormones