EFFECT OF A SATIATING MEAL ON THE CONCENTRATIONS OF PROCOLIPASE PROPEPTIDE IN THE SERUM AND URINE OF NORMAL AND MORBIDLY OBESE SUBJECTS

The effect of a satiating meal on the serum and urinary concentrations of procolipase propeptide (Ala-Pro-Gly-Pro-Arg, APGPR) immunoreactivi ty, as measured by enzyme linked immunosorbent assay (ELISA) specific for free APGPR, has been studied in normal and morbidly obese human su bjects. The normal subjects displayed a biphasic response with coordin ate increases in both serum and urine APGPR immunoreactivity both occu rring within the first two hours after the meal. In two of three of th e morbidly obese subjects, this early rise in APGPR concentration in u rine was not seen but was followed by a slow rise in urinary APGPR imm unoreactivity at four to six hours. In both the normal and obese group s, the urinary immunoreactive signal was found to coelute with synthet ic APGPR on gel chromatography. In rats, procolipase propeptide (Vat-P ro-Asp-Pro-Arg, VPDPR) specifically inhibits fat intake early in the p ostprandial period when given peripherally or centrally. This study su ggests that in humans APGPR reaches the circulation shortly after feed ing and is excreted in the urine. These findings are consistent with t he hypothesis that human procolipase propeptide may also act as a sati ety signal. In addition the late appearance of the peptide in some of the morbidly obese patients could be associated with perturbation of a ppetite control in these subjects.