oxyntomodulin and tyrosyltyrosine

Massive small-bowel resection results in a marked adaptive response in the residual terminal ileum. Increased polyamine synthesis is a necessary component of this response. The ileal L-cell-derived peptides enteroglucagon and peptide tyrosine tyrosine (PYY) have been implicated as humoral mediators of this response. We have previously reported a rapid and sustained increase in glucagon mRNA concentrations after massive small-bowel resection. In this study using an inhibitor of the rate-limiting enzyme in polyamine biosynthesis, ornithine decarboxylase, we have demonstrated that the response of the glucagon and PYY genes to massive small-bowel resection is dependent on polyamine biosynthesis. In addition, we have examined the response of both the ornithine decarboxylase and c-jun genes in this model of intestinal adaptation.

Topics: Animals; Blotting, Northern; Dipeptides; Eflornithine; Female; Gene Expression; Glucagon-Like Peptides; Ileum; Nucleic Acid Hybridization; Ornithine Decarboxylase; Polyamines; Rats; Rats, Sprague-Dawley; RNA, Messenger; Tubulin

To investigate the enterotrophic effects of bolus doses of long chain triglycerides, two groups of eight female Wistar rats were fed identical diets with 48.2% total calories as the essential fatty acid rich oil Efamol. To one group the oil was given in twice daily bolus doses by gavage, while for the other group the oil was mixed with the remainder of the feed and thus consumed over 24 hours. The animals were killed after 20 to 22 days. Bolus dosing significantly increased parameters of mucosal mass along the length of the small intestine in association with an increase in two hour accumulation of vincristine arrested metaphases in small intestinal crypts. In a second experiment, four replicate studies were carried out, each involving two groups of 12 rats respectively fed as described above. After 21 days one animal from each group was killed every two hours, providing regular plasma samples over 24 hours for measurement of gastrin, cholecystokinin, peptide tyrosine-tyrosine and enteroglucagon. Bolus dosing markedly enhanced release of peptide tyrosine-tyrosine and enteroglucagon, but not of gastrin or cholecystokinin. Thus, the enhanced enterotrophic effects of bolus doses of long chain triglycerides could be mediated by release of a distally located gut peptide, perhaps enteroglucagon.

Topics: Animals; Cholecystokinin; Dietary Fats; Dipeptides; Energy Intake; Fatty Acids, Essential; Female; gamma-Linolenic Acid; Gastrins; Gastrointestinal Hormones; Glucagon-Like Peptides; Intestinal Mucosa; Intestine, Small; Linoleic Acids; Oenothera biennis; Organ Size; Plant Oils; Rats; Rats, Inbred Strains