Stimulation of rat pancreatic exocrine secretion by cocaine- and amphetamine-regulated transcript peptide

Cocaine- and amphetamine-regulated transcript (CART) peptide is a recently described neuropeptide that has been localized to areas of the central and peripheral nervous systems. CART has been shown to be involved in feeding behavior when injected centrally, however, its effects upon peripheral tissues have not been studied. This report describes the effects of CART peptide on rat pancreatic exocrine secretion. Infusion of CART peptide caused four-fold increases in amylase secretion from anesthetized rats that had been fashioned with a bile-pancreatic duct cannula. CART peptide-induced increases in pancreatic secretion appear to involve pathways that are sensitive to both acetylcholine (ACh) and cholecystokinin (CCK) since pre-treatment with atropine (ACh receptor antagonist) or L-364,718 (CCK-A receptor antagonist) inhibited the effects of CART peptide on amylase secretion. Pre-treatment with a combination of atropine and L-364,718 abolished the effects of CART peptide. When isolated rat pancreatic acini were exposed to varying doses of CART peptide, no increase in amylase secretion was observed. The results of the present study suggest that CART peptide has stimulatory effects upon pancreatic exocrine secretion. CART peptide-induced increases in pancreatic secretion appear to be indirectly mediated as no direct effect upon pancreatic acini was shown. CART peptide likely acts upon either peripheral or central regulators of pancreatic secretory function that are distant from the acinar unit.