Affiliation:
1. Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington 99164
Abstract
Cholecystokinin (CCK), an endogenous brain-gut peptide, is released after food intake and promotes the process of satiation via activation of the vagus nerve. In vitro, CCK increases cytosolic calcium concentrations and produces membrane depolarization in a subpopulation of vagal afferent neurons. However, the specific mechanisms and ionic conductances that mediate these effects remain unclear. In this study we used calcium imaging, electrophysiological measurements, and single cell PCR analysis on cultured vagal afferent neurons to address this issue directly. A cocktail of blockers of voltage-dependent calcium channels (VDCC) failed to block CCK-induced calcium responses. In addition, SKF96365, a compound that blocks both VDCC and the C family of transient receptor potential (TRP) channels, also failed to prevent responses to CCK. Together these results suggest that CCK-induced calcium influx is not subsequent to the membrane depolarization. Ruthenium red, an inhibitor of the TRPV family and TRPA1, blocked both depolarizing responses to CCK and CCK-induced calcium increases, but had no effect on the KCl-induced calcium response. Selective block of TRPV1 and TRPA1 channels with SB366791 and HC030031, respectively, had minor effects on the CCK-induced response. Application of 2-aminoethoxydiphenyl borate, an activator of select TRPV channels but a blocker of several TRPC channels, either had no effect or enhanced the responses to CCK. Further, results from PCR experiments revealed a significant clustering of TRPV2-5 in neurons expressing CCK1 receptors. These observations demonstrate that CCK-induced increases in cytosolic calcium and membrane depolarization of vagal afferent neurons are likely mediated by TRPV channels, excluding TRPV1.
Reference56 articles.
1. Inhibition of gastric emptying is a physiological action of cholecystokinin.;Debas;Gastroenterology,1975
2. Effects of a novel cholecystokinin (CCK) receptor antagonist, MK-329, on gallbladder contraction and gastric emptying in humans: implications for the physiology of CCK.;Liddle;J Clin Invest,1989
3. L-364,718, a new CCK antagonist, inhibits postprandial pancreatic secretion and PP release in dogs.;Hosotani;Dig Dis Sci,1989
4. Effect of cholecystokinin receptor antagonist on pancreatic responses to exogenous gastrin and cholecystokinin and to meal stimuli.;Konturek;Gastroenterology,1988
5. Physiological mechanisms of cholecystokinin action on pancreatic secretion;Owyang;Am J Physiol,1996
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