IDENTIFICATION OF ENTEROSTATIN, THE PANCREATIC PROCOLIPASE ACTIVATIONPEPTIDE IN THE INTESTINE OF RAT - EFFECT OF CCK-8 AND HIGH-FAT FEEDING

Enterostatin, the procolipase activation peptide, has been suggested i n previous studies to act as a satiety signal for food intake, with a specificity for fat intake. In this study, by use of a competitive enz yme-linked immunosorbent assay with a detection limit of 4.115 nmol/L and within 6% intra- and interassay variation, the immunoreactive and chromatographic characterization of enterostatin in intestinal content was undertaken in Sprague-Dawley rats. Following intravenous infusion of cholecystokinin octapeptide (CCK-8; 200 pmol/kg/h) for 60 min, the concentration of intestinal enterostatin increased from a basal level of 2.0 +/- 0.7 muM to 5.64 +/- 1.1 muM at time point 60 min. The ente rostatin level remained at 4.24 +/- 0.54 muM for 120 min after the CCK infusion had ceased. Pancreatic lipase and colipase activities in rat intestinal content also increased during the CCK-8 infusion. The enzy me activities reached the maximal level after 30 min of CCK infusion a nd thereafter progressively decreased to basal levels, remaining there during the following 2 h. The basal level of intestinal enterostatin in rats fed with standard pellets was found to be increased from 1.42 +/- 0.14 to 3.86 +/- 0.4, 3.17 +/- 0.54, and 5.02 +/- 1.6 muM on days 1, 3, and 7, respectively, after high-fat feeding. Parallel to the inc rease in intestinal enterostatin, there was a significant increase in pancreatic lipase and colipase activities in the intestine during the ingestion period of high-fat diet as compared with the control group. The estimated molecular mass of enterostatin immunoreactivity of intes tinal content was similar to that of the synthetic pentapeptide. These results suggest that immunoreactive enterostatin (Val-Pro-Gly-Pro-Arg ) is normally present in rat intestinal content, is significantly incr eased after stimulation with CCK-8, and is also increased after prolon ged high-fat feeding.