GENERALIZED PRESENCE OF A PEC-6O-LIKE PEPTIDE IN CATECHOLAMINE NEURONS

PEC-60, a 60-residue intestinal peptide structurally related to the pa ncreatic secretory type of trypsin inhibitor, has been isolated, chara cterized and molecularly cloned. It shows biological activity as a hor mone in both the gastrointestinal tract and in the immune system. We n ow report immunohistochemical evidence suggesting its neural localizat ion exclusively within central and peripheral catecholamine (CA) neuro nes. PEC-60-like immunoreactivity was present in cell bodies, dendrite s and nerve terminals of virtually all catecholamine neurones examined and including the noradrenergic gland cells of the adrenal medulla. P EC-60-like immunoreactivity was not seen, however, within the tyrosine hydroxylase-positive but CA-negative arcuate neurones producing growt h hormone releasing hormone. The findings open up the possibility that a PEC-60-like peptide may represent a generalized co-transmitter in t he peripheral and central CA neurones.