PITUITARY ADENYLATE-CYCLASE ACTIVATING POLYPEPTIDE (PACAP)-LIKE IMMUNOREACTIVITY IN GANGLIONEUROBLASTOMA AND NEUROBLASTOMA

Pituitary adenylate cyclase activating polypeptide (PACAP) is a 38 ami no acid peptide originally isolated from ovine hypothalamus. It has a potent stimulatory action on adenylate cyclase in the rat pituitary. T he presence of PACAP was studied in the tumor tissues of ganglioneurob lastoma and neuroblastoma by radioimmunoassay and immunocytochemistry. Immunocytochemical studies showed positive immunostaining in 4 out of 7 ganglioneuroblastomas and 4 out of 6 neuroblastomas. Immunoreactive PACAP concentrations in tissues of 3 gangioneuroblastomas ranged from 14.5 to 27.8 pmol/g wet weight (20.0 +/- 5.7 pmol/g wet weight, mean +/- S.D.) and the concentration in one neuroblastoma tissue was 111.0 pmol/g wet weight. Reverse phase high performance liquid chromatograph y of the tumor tissue extract of ganglioneuroblastoma showed a peak el uting in the position of PACAP1-38 and smaller broad peaks eluting lat er. These results indicated that high concentrations of immunoreactive PACAP were present in the tumor tissues of ganglioneuroblastoma and n euroblastoma, and suggest the possibility that this peptide plays a pa thophysiological role in some ganglioneuroblastomas and neuroblastomas .