Stability of gastrin in the gastrointestinal lumen of suckling, weanling and adult pigs

Abstract

It has been reported in the literature that a large quantity of gastrin is released into the gastric lumen in various species. This study was aimed to examine the stability of gastrin in the gastrointestinal (GI) lumen of pigs. Iodine-labelled little (G17) and big gastrin (G34) were incubated in vitro with the GI luminal fluids of suckling, weanling and adult pigs at 37°C for 20 min, and the degradation of the peptide was measured by monitoring the generation of trichloroacetic acid soluble radioactivity. The degradation rate of G17 in the gastric fluids of all animals was less than 10%, while the degradation of G34 was less than 15% in the gastric fluids of suckling and adult pigs and about 25% in the gastric fluids of weanling pigs. The degradation rates of G17 and G34 in the small intestinal fluids of suckling pigs were between 18 and 30%, and were significantly lower than the corresponding rates in the intestinal fluids of weanling and adult pigs, the latter were between 35 and 67%. Addition of defatted porcine colostrum or its components, the casein or acid-soluble fraction, inhibited gastrin degradation in the intestinal fluids with the casein fraction having highest inhibition potency. These results indicate that gastrin is stable in the GI lumen of the suckling pigs and porcine colostrum protects gastrin from luminal hydrolysis in the small intestine, suggesting a potential physiological role of luminally released gastrin in suckling animals.