Possible Interaction: Cholecystokinin and Tryptophan

“Intraluminal application of melatonin, its precursor: L-tryptophan , leptin or ghrelin dose-dependently increased plasma CCK level.”

“ Tryptophan stimulates plasma cholecystokinin and pyloric pressures, both of which slow gastric emptying.”

“The 20 mM Trp concentration promoted the secretion of cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP), elevated the mRNA level of CaSR, and upregulated the protein levels of CaSR, protein kinase C (PKC), and inositol trisphosphate receptor (IP3R).”

“The cholecystokinin CCK ) concentrations in the hypothalamus were significantly decreased by tryptophan treatment but not by imipramine and cyproheptadine, which changed the serotonergic function.”

“Both phenylalanine and tryptophan gradually enhanced plasma CCK concentrations with time after infusion.”

“These data suggest that L-tryptophan directly regulates the release of cholecystokinin and that membrane depolarization and intracellular generation of cyclic adenosine monophosphate may play a role in activating cholecystokinin cells.”

“The secretory response evoked by CCK-PZ was inhibited by other amino acids (Ala, Asp, Asn, Gly, Ile, Leu, Lys, Met, Phe, Pro, Thr, Trp , Val, in each 20 mM).”

“Although L-tryptophan inhibited the actions of cholecystokinin , L-phenylalanine, L-methionine or L-aspartic acid, even when tested at concentrations as high as 3 mM, did not alter the action of cholecystokinin on pancreatic acini.”

“Results with butyloxycarbonyl-L-tryptophan indicated that the inhibition of the action of cholecystokinin caused by L-tryptophan and various acyl derivatives is specific, competitive and fully reversible.”

“These findings suggest that the charge donor capacity of the tryptophan residue is of primary importance for the biologic activity of pancreozymin , while hydrogen bond formation and hydrophobicity are of secondary importance.”

“Endogenous cholecystokinin CCK ) released by intraduodenal instillation of L-leucine and L-tryptophan mixture reduced acid response from PP by about 50% and caused an increase in pancreatic protein output equal to that reached with 120 ng/kg-hr of caerulein.”