IMMUNOHISTOCHEMICAL DETECTION OF SECRETONEURIN, A NOVEL NEUROPEPTIDE ENDOPROTEOLYTICALLY PROCESSED FROM SECRETOGRANIN-II, IN NORMAL HUMAN ENDOCRINE AND NEURONAL TISSUES

An antiserum raised against a synthetic peptide derived from the prima ry amino sequence of rat secretogranin II (chromogranin C) was used fo r immunological (quantitative radioimmunoassay analysis) and immunohis tochemical studies of normal human endocrine and nervous tissues. This antibody recognized a novel and biologically active neuropeptide whic h was coined as secretoneurin. In endocrine tissues, secretoneurin was mainly co-localized with chromogranin A and B with some exceptions (e .g., parathyroid gland). Secretoneurin was demonstrated immunohistoche mically in the adrenal medulla, thyroid C cells, TSH- and FSH/LH-produ cing cells of the anterior pituitary, A and B cells of pancreatic isle ts, in endocrine cells of the gastrointestinal tract and the bronchial mucosa, and the prostate. Immunoreactivity determined by radioimmunoa ssay analysis revealed high secretoneurin levels in the anterior and p osterior pituitary and lower levels in pancreatic and thyroid tissue. A strong secretoneurin immunoreactivity was also found in ganglion cel ls of the submucosal and myenteric plexus of the gastrointestinal trac t, and in ganglionic cells of dorsal root ganglia, peripheral nerves, and ganglion cells of the adrenal medulla. Thus, secretoneurin may ser ve as a useful marker of gangliocytic/neuronal differentiation.