This work is an attempt to demonstrate the applicability of peptide antagonists and monoclonal antibodies for blocking certain regulatory elements of pancreatic function in vivo. Data from the experiments using these tools suggest that circulating CCK, indeed, is a primary factor in regulating pancreatic enzyme secretion acting on CCK-A receptors in rats. Bombesin-like peptides play a minor role in mediating pancreatic function under physiological conditions, although gastrin-releasing peptide-preferring receptors are located on pancreatic acini. Immunoneutralization of circulating somatostatin led to an increased pancreatic secretory response to CCK stimulation, suggesting an inhibitory role of endogenous somatostatin. Receptor antagonists that antagonize the actions of galanin in the central nervous system, behaved as partial agonists of the peptide on the exocrine pancreas. Therefore, these antagonists are not suitable for evaluation of the physiological role of galanin in this organ. In conclusion, regulation of exocrine pancreatic function is complex, involving several bioactive peptides, and this control is not completely understood, as yet. Selective receptor antagonists and monoclonal antibodies are useful tools to identify the role of bioactive peptides in this function.
