EFFECT OF THE LECTINS WHEAT-GERM-AGGLUTININ (WGA) AND ULEX-EUROPAEUS AGGLUTININ (UEA-I) ON THE ALPHA-AMYLASE SECRETION OF RAT PANCREAS IN-VITRO AND IN-VIVO

Lectins are able to bind to cholecystokinin (CCK) receptors and other glycosylated membrane proteins. The lectins wheat germ agglutinin (WGA ) and Ulex europaeus agglutinin (UEA-I) are used for affinity chromato graphy to isolate the highly glycosylated CCK-A receptor of pancreatic acinar cells. According to the working hypothesis that lectin binding to the CCK receptor should alter the ligand-receptor interaction, the effect of WGA and UEA-I on CCK-8-induced enzyme secretion was studied on isolated rat pancreatic acini in vitro. In vitro both lectins show ed a dosage-dependent inhibition of CCK-8-induced alpha-amylase secret ion of acini over 60 min. WGA showed a strong inhibitory effect on amy lase secretion, similar to 40%, in vitro. UEA-I caused a smaller, but significant decrease, similar to 20%, in enzyme secretion of isolated acini. Additionally, both lectins inhibited cerulein/secretin- or ceru lein-induced pancreatic secretion of rats in vivo, but not after secre tin alone. The results are discussed with respect to a possible influe nce of both lectins on the interaction of CCK or cerulein with the CCK -A receptor.