Effects of a transplantable insulinoma upon regulatory peptide concentrations in the gastrointestinal tract of the rat.
The rapid growth (0.8 +/- 0.3 g/day) of a transplantable insulinoma, which also contained substance P (2.9 +/- 2.3 pmol/g) and gastrin-releasing peptide (3.2 +/- 2.1 pmol/g), resulted in the development of hyperphagia, hyperinsulinaemia and hypoglycaemia in rats (n = 8). After a 14-day growth period, the insulinoma-bearing rats showed an increase (49%; p less than 0.01) in the weight of the small intestine but no significant change in stomach weight compared with control animals. The content (pmol/organ) of somatostatin, substance P, neurokinin A and vasoactive intestinal peptide in the stomachs of the tumour rats was unchanged. A depletion in the content (53% p less than 0.01) and concentration (57%; p less than 0.01) of gastrin-releasing peptide, however, suggested either hypersecretion, possibly mediated through hypoglycaemia-induced vagal stimulation, or inhibition of synthesis. The concentration and content of glucagon-like immunoreactivity (enteroglucagon) in the small intestine of the insulinoma rats increased markedly (47%; p less than 0.01 and 120%; p less than 0.01). This increase is consistent with a proposed role of this peptide as a factor trophic to the intestinal mucosa. No significant changes in the concentrations of somatostatin, substance P, neurokinin A, vasoactive intestinal peptide and gastrin-releasing peptide in the small intestine were observed. However, the increase in gut weight resulted in a greater content of vasoactive intestinal peptide (40%; p less than 0.01) and substance P (37%; p less than 0.05) in the insulinoma rats.
D007516:Adenoma, Islet Cell / Q000503:physiopathology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D004435:Eating; D002149:Energy Intake; D005768:Gastrointestinal Hormones / Q000378:metabolism*; D005934:Glucagon / Q000378:metabolism*; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007340:Insulinoma / Q000503:physiopathology*; D008297:Male; D009368:Neoplasm Transplantation; D010190:Pancreatic Neoplasms / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D005768:Gastrointestinal Hormones; D007328:Insulin; D005934:Glucagon