pancreastatin and glycine-amide

Pancreastatin is a 49 amino acid peptide with a C-terminal glycine amide originally isolated from porcine pancreas. There are strong indications that pancreastatin is derived from chromogranin A, since the amino acid sequence 240-288 in porcine chromogranin A contains pancreastatin flanked by typical signals for proteolytic processing. Several molecular forms of immunoreactive pancreastatin have been reported to be present in porcine adrenal medulla, but no information on the secretion of the peptides is available. We studied stimuli for the release of immunoreactive pancreastatin from adrenal glands as well as the molecular nature of the released immunoreactivity using isolated, perfused, porcine adrenal glands with intact splanchnic nerve supply and a radioimmunoassay specific for the C-terminal glycine amide of porcine pancreastatin in combination with chromatography. Stimulation of the splanchnic nerves greatly enhanced the release of immunoreactive pancreastatin by a mechanism that seems to involve cholinergic nicotinic transmission. The pancreastatin immunoreactivity was due to large amounts of a N-terminally extended pancreastatin form, possibly corresponding to the chromogranin A(1-288) fragment and small amounts of pancreastatin and a C-terminal pancreastatin fragment. Adrenal extracts also contained unprocessed chromogranin A. We conclude that in the porcine adrenals at least 25% of chromogranin A is processed to smaller molecular forms with the pancreastatin sequence forming their C-terminus. These forms appear to be released in parallel with the catecholamines.

Topics: Adrenal Glands; Animals; Chromatography, Gel; Chromatography, High Pressure Liquid; Chromogranin A; Electric Stimulation; Glycine; In Vitro Techniques; Pancreatic Hormones; Perfusion; Radioimmunoassay; Sensitivity and Specificity; Splanchnic Nerves; Swine