Response of plasma and tissue levels of enteroglucagon immunoreactivity to intestinal resection, lactation and hyperphagia

Elevation of plasma enteroglucagon has been described in the presence of intestinal hyperplasia in both animals and man. In order to investigate whether enteroglucagon plays a role in the stimulation of small intestinal growth, fasting plasma and small intestinal tissue levels of enteroglucagon immunoreactivity were measured in control rats and in 3 different rat models of intestinal adaptation: 5 weeks after proximal and distal small bowel resection, on the 12th day of lactation and following 5 weeks of cold acclimation induced hyperphagia. Plasma enteroglucagon levels increased significantly from the control value of 89±(SEM) 13.1 fmol/ml to 147±13.6 after proximal resection (p < 0.005) and to 207±32.6 following 5 weeks of hyperphagia (p < 0.001). During lactation ileal tissue enteroglucagon increased by 183% from 58.1±8.6 pmol/g tissue in controls to 163.9±20.4 (p < 0.001). Ileal tissue enteroglucagon levels were also elevated by 60% following proximal resection (p < 0.005) and by 91% following the hyperphagia of cold-acclimation (p < 0.005). In contrast, jejunal tissue enteroglucagon levels of cold-acclimated rats were only increased by 55% when compared to the control value of 27±2.9 pmol/g tissue (p < 0.02). These results confirm that in the rat, ileal enteroglucagon levels are significantly greater than those found in the jejunum (p < 0.005). Enteroglucagon levels were also significantly elevated in the 2 groups of rats with hyperphagia, namely the lactating and cold-acclimated groups. The data lend further support to the proposal that enteroglucagon may play a trophic role in producing intestinal growth.