Immunocytochemical characterization of ACTH-like immunoreactivity in cerebral nerves and in endocrine cells of the pituitary and gastrointestinal tract by using region-specific antisera.

The development and use of region-specific antisera for characterizing pituitary and extrapituitary ACTH immunoreactivity are described. The pituitary corticotrophs and melanotrophs, as well as a system of cerebral nerves, contain antigenic determinants, indistinguishable from those of true, pituitary ACTH [1-39]. The distributional patterns of cerebral nerves, most probably containing ACTH [1-39], is of interest in view of documented behavioral effects of ACTH fragments, as well as the possible interaction between ACTH and certain opioid peptides. Studies on antropyloric gastrin cells, previously reported to contain immunoreactive ACTH-like material indicate that the main form of immunoreactive peptide stored in these cells contains only part of the ACTH [1-39] sequence. Its relation to fragments of the ACTH molecule, as well as to yet unknown (hormonal) peptides, is discussed.