Calcium-sensing receptor-mediated L-tryptophan-induced secretion of cholecystokinin and glucose-dependent insulinotropic peptide in swine duodenum

This study aimed to understand the effect of Tryptophan (Trp) on gut hormones secretion as well as the roles of the CaSR and its downstream signaling pathway in gut hormones secretion using swine duodenal perfusion . Swine duodenum was perfused with Krebs-Henseleit buffers (KHB) as a basal solution. Various concentrations (0, 10 mM and 20 mM) of Trp were applied to investigate the effect of Trp on gut hormones secretion. A CaSR antagonist was used to detect the involvement of CaSR and its signal molecules. An amount of 20 mM Trp promoted the secretion of cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP); elevated the mRNA level of ; and unregulated the protein level of CaSR, Protein Kinase C (PKC) and Inositol trisphosphate receptor (IP3R). However, NPS 2143, an inhibitor of CaSR, attenuated the CCK and GIP release; reduced the mRNA level of ; and decreased the protein level of CaSR, PKC and IP3R in the perfusion with 20 mM Trp. The study indicated that CCK and GIP secretion can be induced by Trp in swine duodenum , and this effect is mediated by CaSR and its downstream signal molecules PKC and IP3R.