Effect of food ingestion on intestinal glucagon-like immunoreactivity (GLI) secretion in normal and gastrectomized subjects

Abstract

Summary. This work was undertaken to compare the intestinal GLI responses to oral glucose (1.75 g/kg, 25% sol.), to a carbohydrate-rich meal (carbohydrate content about 1.75 g/kg) and to a protein meal (250-400 g grilled lean beef) in normal (n = 6) and gastrectomized (n = 6) subjects. As expected, after glucose administration the elevation of plasma GLI was more pronounced in the gastrectomy group (-500% above baseline) than in the controls (= 75% above baseline). However, the gastrectomized patients responded to the carbohydrate meal with a very slight elevation of circulating GLI (= 45% above baseline), similar to that found in the controls (= 70% above baseline). After the protein meal, a small increase of GLI was also observed in both groups. -In conclusion, in gastrectomized subjects the ingestion of natural foodstuffs is followed by a normal elevation of plasma GLI, thereby suggesting the exclusion of this factor from involvement in the constellation of postgastrectomy syndrome. In these patients, the exaggerated rise in GLI after oral glucose is not representative of increments after physiological stimuli.Key words: Gastrectomized and normal subjects, glucose and food ingestion, glucagon, intestinal glucagon-like immunoreactivity (GLI), insulin. In gastrectomized patients, the secretion of intestinal glucagon-like immunoreactivity (GLI) observed throughout the course of an oral glucose tolerance test (OGTT) is more intense (three-fivefold) than in normal subjects [1,2,3,4,5,6]. Arising from these findings, speculation has been made about the possible implication of high levels of circulating GLI in the pathogenesis of some aspects of the postgastrectomy syndrome, such as dumping [5] and reactive hypoglycaemia [6]. However, the aforementioned condition, induced by the ingestion of a large amount of glucose solution, is obviously not a physiological situation.To obtain information about the effect of ingestion of natural foodstuffs on GLI secretion, in the present work we have examined the plasma GLI levels after consumption of carbohydrate and protein-rich meals in normal and gastrectomized subjects. Materials and MethodsThe control group consisted of six healthy volunteers (four males and two females) whose ages ranged from 24 to 46 years. None of them appeared to be obese (+ 10% ideal body weight according to the Metropolitan Life Insurance Company tables). The test group consisted of six male subjects who had undergone subtotal gastric resection (Billroth II) because of the presence of a benign ulcer not controllable by medical treatment. Their ages ranged from 32 to 48 years. None of them were underweight by more than 10% of the ideal body weight and none suffered from other apparent illness.All individuals were subjected to three tests. First, to an oral glucose tolerance test; glucose (1.75 g per kg of body weight) was taken as a 25%