Enteroglucagon. A putative humoral factor inducing pancreatic hyperplasia after proximal small bowel resection

Differential response of protein metabolism in splanchnic organs and muscle to pectin feeding

The aim of the present study was to determine whether the addition of soluble fibre in the diet affected protein metabolism in the intestinal tissues, some visceral organs and in skeletal muscle. A diet supplemented with pectin (80 g/kg) was fed to young growing rats and the effect on organ mass and protein metabolism in liver, spleen, small and large intestines and gastrocnemius muscle was monitored and compared with the control group. Protein synthesis rates were determined by measuring [13C]valine incorporation in tissue protein. In the pectin-fed rats compared with the controls, DM intake and body weight gain were reduced (9 and 20 %, respectively) as well as gastrocnemius muscle, liver and spleen weights (6, 14 and 11 %, respectively), but the intestinal tissues were increased (64 %). In the intestinal tissues all protein metabolism parameters (protein and RNA content, protein synthesis rate and translational efficiency) were increased in the pectin group. In liver the translational efficiency was also increased, whereas its protein and RNA contents were reduced in the pectin group. In gastrocnemius muscle, protein content, fractional and absolute protein synthesis rates and translational efficiency were lower in the pectin group. The stimulation of protein turnover in intestines and liver by soluble fibre such as pectins could be one of the factors that explain the decrease in muscle turnover and whole-body growth rate.

Trophic effects of glicentin on rat small-intestinal mucosa in vivo and in vitro

To define the role of glicentin the active site of enteroglucagon, we evaluated the trophic effects of recombinant rat glicentin on rat small intestine and IEC-6 cells. In vivo, a significant increase was observed in jejunal wet weight, protein content, DNA content, and alkaline phosphatase activity after the subcutaneous administration of 100 micrograms/kg per day of glicentin for 2 weeks. In the ileum, however, there were no significant differences between the control versus glicentin groups in any of these parameters. Ornithine decarboxylase (ODC) activity 3.5 h after an intraperitoneal injection of glicentin was increased in the jejunal mucosa, but not in the ileal mucosa. In vitro, glicentin, at a dose of more than 100 ng/ml, significantly increased both tritium-thymidine incorporation and the number of IEC-6 cells. These findings indicate that glicentin exerts direct trophic effects on the rat small-intestinal mucosa and on the rat small-intestinal cell line, IEC-6, and that this peptide appears to be an active site of enteroglucagon.

Effect of ageing on pancreatic hyperplasia after 90% proximal small bowel resection

The present study was performed to examine the effect of ageing on pancreatic hyperplasia observed after proximal small bowel resection (PSBR). Young and old Wistar rats were randomly assigned to two groups, which underwent either an approximate 90% PSBR or a jejunal and ileal transection (TRC). One week after the operation, the pancreatic wet weight and the protein, DNA and RNA content of the pancreas were all significantly higher in young PSBR rats than in young TRC rats. However, no differences were seen in the old rat groups. Plasma enteroglucagon levels were elevated in both young and old PSBR rats, but the ratio of increase between the PSBR and TRC groups was significantly higher in young rats. Plasma cholecystokinin and gastrin levels did not increase after PSBR in either the young or old rats. These findings suggest that pancreatic hyperplasia observed after PSBR is attenuated by ageing, probably due to an insufficient increase in plasma enteroglucagon levels.