Plasma enteroglucagon and CCK levels and cell proliferation in defunctioned small bowel in the rat

Luminal nutrients exert a powerful trophic effect on small bowel mucosa. Recent evidence suggests that a circulating factor, possibly enteroglucagon, is also growth-promoting. In order to study the isolated effect of nonluminal influences on bowel mucosa, Thiry-Vella fistulae (TVF) were constructed in rats. Circulating enteric hormone concentrations were manipulated by resecting different lengths of remaining gut. Thirty-two male Wistar rats had either 25%, 50%, 75%, or 90% proximal small bowel resection. In each animal the first 25% of resected bowel was exteriorized as a Thiry-Vella fistula. Seven control rats underwent jejunal transection. Twelve days postoperatively the fasted animals were killed, and circulating and tissue concentrations of enteroglucagon and CCK were estimated by radioimmunoassay. Crypt-cell production rate was used as an index of cellular proliferation in the Thiry-Vella fistulae. Proximal small bowel defunctioned in the Thirty-Vella fistulae had a significantly lower crypt-cell production rate and enteroglucagon and CCK content than the equivalent segment in transected rats. Further small bowel resection produced a subsequent increase in circulating enteroglucagon and CCK concentrations, an increase in the Thiry-Vella fistula content of these hormones, and a doubling of the crypt-cell production rate in the Thiry-Vella fistulae. These results show that circulating enteroglucagon and CCK concentrations match closely with enterocyte production even when luminal influences are excluded. It is suggested that circulating factors may play a major role in postresectional ileal hyperplasia. This hyperplasia apparently affects endocrine cells as well as enterocytes.

Plasma enteroglucagon related to malabsorption in coeliac disease

Plasma enteroglucagon was measured before and during three hours after a standard meal in 21 untreated adult patients with suspected coeliac disease who all had villous atrophy of the small intestinal mucosa and malabsorption, and in nine control subjects. In 11 of these patients the diagnosis of coeliac disease was confirmed and 10 were again investigated on a gluten free diet. The coeliac patients had higher basal (37 +/- 9 pmol/l, mean +/- SE, p less than 0.05) and postprandial (70 +/- 9 pmol/l, p less than 0.005) mean plasma enteroglucagon concentrations than the control subjects (basal 14 +/- 4 pmol/l, postprandial 25 +/- 5 pmol/l). The 10 coeliac patients on gluten free diet for five to 20 months had a basal mean plasma enteroglucagon concentration not significantly lower than before treatment (25 +/- 5 pmol/l) but significantly lower postprandial enteroglucagon concentrations than before treatment (40 +/- 7 pmol/l, p less than 0.025). Postprandial plasma enteroglucagon concentration after 90 minutes in untreated patients correlated positively to the faecal fat excretion (r = 0.58, p less than 0.02). It correlated negatively to the urinary five hour D-xylose excretion after an oral load of 165 mmol D-xylose (r = -0.71, p less than 0.01). Thus, the postprandial plasma enteroglucagon concentrations in untreated coeliac disease were related to the degree of malabsorption and they normalised during treatment with a gluten free diet.

The ileal brake--inhibition of jejunal motility after ileal fat perfusion in man

The possibility that malabsorbed fat passing through the human ileum exerts an inhibitory feedback control on jejunal motility has been investigated in 24 normal subjects by perfusing the ileum with a fat containing solution designed to produce ileal luminal fat concentrations similar to those in steatorrhoea (30-40 mg/ml). Mean transit times through a 30 cm saline perfused jejunal segment were measured by a dye dilution technique. Thirty minutes after ileal fat perfusion, mean transit times rose markedly to 18.9 +/- 2.5 minutes from a control value of 7.5 +/- 0.9 minutes (n = 5; p less than 0.05). This was associated with an increase in volume of the perfused segment which rose to 175.1 +/- 22.9 ml (control 97.6 +/- 10.3 ml, n = 5; p less than 0.05). Transit times and segmental volumes had returned towards basal values 90 minutes after completing the fat perfusion. Further studies showed that ileal fat perfusion produced a pronounced inhibition of jejunal pressure wave activity, percentage duration of activity falling from a control level of 40.3 +/- 5.0% to 14.9 +/- 2.8% in the hour after ileal perfusion (p less than 0.01). Ileal fat perfusion was associated with marked rises in plasma enteroglucagon and neurotensin, the peak values (218 +/- 37 and 68 +/- 13.1 pmol/l) being comparable with those observed postprandially in coeliac disease. These observations show the existence in man of an inhibitory intestinal control mechanism, whereby ileal fat perfusion inhibits jejunal motility and delays caudal transit of jejunal contents.

Effect of infusion of nutrient solutions into the ileum on gastrointestinal transit and plasma levels of neurotensin and enteroglucagon

The small bowel transit time of 100 ml of lactulose solution infused at the ligament of Treitz was measured by breath hydrogen excretion in paired studies carried out in 43 healthy volunteers during infusion (1.2 ml/min) of equal volumes (100 ml) of isotonic solutions of either fat emulsion (Intralipid, Prosparol, or Calogen), protein hydrolysate, glucose, or saline into either the jejunum (90 cm from the teeth), ileum (205 cm from the teeth), or colon (350 or 400 cm from the teeth). Ileal infusion of Intralipid or protein hydrolysate resulted in significant delays in small bowel transit time (125 +/- 21 min and 71 +/- 11 min, respectively) compared with infusion of saline (50 +/- 3 min; p less than 0.02 and p less than 0.05). These delays were not associated with any significant alteration in plasma levels of neurotensin or enteroglucagon. Small bowel transit time was unaffected by infusion of nutrients into the colon or jejunum, although jejunal infusion of Intralipid increased the plasma levels of enteroglucagon and neurotensin (p less than 0.01 and p less than 0.02, respectively) after the start of lactulose infusion. In a separate series of paired experiments, infusion of Intralipid into the ileum in 5 volunteers significantly delayed the transit of a solid test meal labeled with 25 microCi of 99mTc-sulfur colloid through both the stomach and small intestine. These data support the existence of a mechanism whereby the presence of unabsorbed food in the ileum may enhance absorption by delaying the passage of food through the small intestine.

Pattern of cell proliferation and enteroglucagon response following small bowel resection in the rat

Gut resection triggers off a complex series of adaptive changes in the remaining bowel. There is evidence that these are partly mediated by hormonal factors and enteroglucagons have been proposed as candidates for this role. It is uncertain, however, whether plasma enteroglucagon concentrations rise quickly enough to be involved in the rapid initial response or are persistent enough for chronic maintenance. Plasma concentrations of enteroglucagon were therefore estimated at varying times following gut resection and related to crypt cell production rate (CCPR), which was used as an index of cellular proliferation. 96 male Wistar rats had either 75% proximal small bowel resection or jejunal transection (controls). Groups of animals were killed at 1.5, 3, 6, 12, 24 and 48 days following operation and the plasma enteroglucagon and CCPR in the terminal ileum were estimated. Both values were markedly elevated at 1.5 days and continued to rise in a very similar manner in the resected group of rats. Gel permeation chromatography on Sephadex G-50 of plasma samples showed that the increase in plasma enteroglucagon was mainly due to an increase in a component of Kav 0.25, of similar molecular size to that of porcine glicentin. Thus the principal form of enteroglucagon, as a possible trophic hormone, does respond sufficiently quickly, and the response is maintained for long enough, to be involved throughout the adaptive process.

Determination of enteroglucagon in plasma for detection of celiac disease in children

To evaluate the plasma enteroglucagon assay as a test for the detection of celiac disease, we have determined basal and postprandial concentrations of enteroglucagon in plasma of children who underwent small-intestinal biopsy because of suspected celiac disease. In the 14 children with untreated celiac disease both basal [81 (SD 33) pmol/L] and postprandial [129 (SD 26) pmol/L] concentrations of enteroglucagon were significantly higher (p less than 0.001) than in the 45 children with other gastrointestinal disorders [24 (SD 9) pmol/L, and 50 (SD 22) pmol/L, respectively] and in the 15 children without gastrointestinal disorders [14 (SD 10) pmol/L, and 35 (SD 8) pmol/L, respectively]. All children with celiac disease had either basal or postprandial plasma enteroglucagon concentrations exceeding the mean + 2 SD of the results for the children with other gastrointestinal disorders. Eight of 10 children with celiac disease in whom both concentrations were measured had increased values for both. In our study the sensitivity for detection of celiac disease was 100% and the specificity 97%. Evidently determination of plasma enteroglucagon concentration is effective in diagnosing celiac disease, thereby improving the selection of patients for small-intestinal biopsy.

Cell proliferation, plasma enteroglucagon and plasma gastrin levels in starved and refed rats

The effects of starvation and refeeding on intestinal cell proliferation at several sites of the rat gastrointestinal tract were studied and used as a model of altered cell proliferation in order to investigate the relationship between the rate of cell production and plasma gastrin and enteroglucagon. There was a marked fall in crypt cell production rate after four days starvation, with the proximal sites of the gut being most affected. The response to refeeding varied with site, suggesting that there was more than one mechanism for the control of intestinal cell proliferation. Plasma gastrin and enteroglucagon both fell to one fifth of their control level after starvation. Plasma gastrin increased slowly after refeeding, whilst plasma enteroglucagon increased rapidly to values significantly above control. Plasma gastrin was only correlated with crypt cell production in the duodenum, while plasma enteroglucagon was correlated with crypt cell production rate at several sites, indicating that enteroglucagon may be involved in the control of intestinal cell production.

Long-term treatment in diabetics with acarbose, a glucosidase inhibitor: efficacy, tolerability and effect on GI hormones

12 months therapy with acarbose in 143 type I and type II patients markedly improved the metabolic control, assessed by fasting and postprandial blood glucose determination. During 5 year acarbose treatment GIP levels were decreased and enteroglucagon levels were elevated. After withdrawal of the drug for one week GIP levels increased and enteroglucagon concentrations fell. Thus, GI-hormone changes were reversible after discontinuation of acarbose. Tolerability of acarbose was good and clinical chemistry and haematology parameters showed no changes after 1-5 years acarbose therapy. Approximately 60% of the patients had intestinal symptoms which subsided again for most patients after 1-4 weeks therapy with acarbose. Body weight remained unchanged. The glucosidase inhibitor acarbose is a new effective and safe therapeutic concept in the treatment of diabetes mellitus.

Gut hormones in inflammatory bowel disease

We have studied fasting levels and the response to a standard test breakfast of blood glucose and several gut hormones in 24 patients with ulcerative colitis, in 14 patients with Crohn's disease, and in 14 healthy control subjects. Patients with ulcerative colitis had significantly elevated fasting human pancreatic polypeptide (HPP) concentrations, and both basal and postprandial levels of gastrin, gastric inhibitory polypeptide (GIP), and motilin were greater than normal. In contrast, patients with Crohn's disease had normal gastrin levels but had increased fasting and postprandial levels of GIP and motilin and, in addition, of enteroglucagon, compared with controls. These patients also had greater than normal HPP concentrations 30 min after the breakfast. Normal levels of insulin, pancreatic glucagon, neurotensin, and vasoactive intestinal polypeptide were found in both groups of patients. Much remains to be known about the pathophysiology of these two debilitating diseases, and the abnormal release of gut hormones may be of importance.

Relation of enteroinsular hormones at birth to macrosomia and neonatal hypoglycemia in infants of diabetic mothers

To study the role of enteroinsular hormones in fetal macrosomia and neonatal hypoglycemia in infants of diabetic mothers, we measured plasma concentrations of free and total immunoreactive insulin, C-peptide, pancreatic glucagon, enteroglucagon, and gastric inhibitory polypeptide at birth in 35 IDMs and 35 infants of normal mothers. Twenty fasting adults of normal weight were also studied. Sixteen IDMs were macrosomic at birth; 17 developed neonatal hypoglycemia over the first postnatal hours. The IDMs had ten times higher concentrations of free IRI than the normal infants in cord blood. Free IRI concentrations were related to the severity of maternal diabetes, with the infants of white class D to F mothers having the highest levels. The IDMs with macrosomia had a twofold increase in the concentrations of free IRI when compared with IDMs of normal weight. There was a significant correlation between the birth weight ratio and the concentrations of free IRI. The IDMs who developed neonatal hypoglycemia had considerably higher concentrations of free IRI than did normoglycemic IDMs. The decrease of blood glucose over the first postnatal hours correlated strongly with the free IRI concentrations in the cord blood. The IDMs had a threefold increase of the C-peptide concentrations over those in normal infants. Six IDMs had a molar ratio of C-peptide to free IRI of less than 1. Both the IDMs and normal infants had substantially higher concentrations of enteroglucagon and lower concentrations of GIP than did the fasting adults. Our data provide direct evidence that IDMs are markedly hyperinsulinemic at birth and that ambient hyperinsulinemia plays a crucial role in the development of fetal macrosomia and neonatal hypoglycemia. Moreover, the observed discrepancy in the relative increase of free IRI and C-peptide, combined with the low molar ratio of C-peptide to IRI, suggests a decreased metabolic clearance of insulin or transplacental passage of insulin from the maternal circulation in infants of mothers with insulin-treated diabetes.

Molecular forms of human enteroglucagon in tissue and plasma: plasma responses to nutrient stimuli in health and in disorders of the upper gastrointestinal tract

A means of estimating human enteroglucagon (glucagon-like immunoreactivity of intestinal origin) in tissues and plasma is described, based on the subtraction of RIA values obtained with the C-terminal-directed glucagon antiserum RCS5 from the total glucagon-like immunoreactivity determined with the N-terminal- to midmolecule-directed glucagon antiserum R59. Gel filtration on Sephadex G-50 of human plasma and extracts of normal human intestine separated the R59 immunoreactivity into three peaks: a small peak of void volume material, a major peak coeluting with porcine glicentin, and a smaller peak coeluting with pancreatic glucagon. No RCS5 immunoreactivity was detected in the human gut, except for a small amount constituting less than 2% of the total glucagon-like immunoreactivity in the ileum and rectum only. In extracts of human pancreas, the chromatographic profiles obtained with RCS5 and R59 assays differed from the intestinal patterns, but were identical to each other, giving no evidence of a significant amount of pancreatic R59 immunoreactivity that was not also reactive with RCS5. Chromatography of plasmas from healthy subjects and patients with dumping syndrome, active coeliac disease, and tropical sprue showed that only the second major peak of R59 immunoreactivity reflected the basal or postnutrient increases in the plasma enteroglucagon concentration. In patients with exaggerated enteroglucagon release, the rise was again found to be entirely due to an increase in this peak of immunoreactivity. This major molecular form of human enteroglucagon, similar in size to porcine glicentin, is, thus, the form most likely to be of physiological and pathophysiological significance.

The role of pancreatico-biliary secretions in intestinal adaptation after resection, and its relationship to plasma enteroglucagon

Two groups, each containing 16 male Wistar rats, had either 75 per cent small bowel resection or jejunal transection; 8 animals from each group; had previously been subjected to pancreatico-biliary diversion. All animals were killed 12 days after the operation, plasma enteroglucagon levels were measured and crypt cell production rate (CCPR) at different sites of the remaining small intestine was measured using a metaphase arrest technique with vincristine. In each of the resected groups there was a significant increase in the CCPR and enteroglucagon levels compared with the transected groups. Furthermore it was found that the CCPR and enteroglucagon levels were higher in the resected group without the pancreatico-biliary diversion compared with the resected group with the diversion. This study, although it confirms the importance of pancreatico-biliary secretions in intestinal adaptation, could also indicate that a humoral factor may be important in the control of intestinal cell proliferation. Our findings do not exclude the possibility that enteroglucagon could be a candidate for such a role.

Gut hormones in acute diarrhoea

The gut hormone response to a breakfast meal was studied in 12 subjects hospitalised for an episode of acute diarrhoea (presumed infective) who were otherwise well and in 13 healthy control subjects. Fasting blood glucose concentrations were low but basal insulin concentrations were raised. Basal concentrations of pancreatic polypeptide and both basal and postprandial responses of motilin, enteroglucagon, and vasoactive intestinal polypeptide (VIP) were also significantly greater than controls. No abnormalities in plasma concentrations of gastrin, gastric inhibitory polypeptide (GIP) or pancreatic glucagon were found. The suggested physiological actions of the raised hormones may be relevant to the pathophysiology of diarrhoea.

Evidence for a humoral mechanism after small intestinal resection. Exclusion of gastrin but not enteroglucagon

It is generally agreed that the adaptive response in the residual bowel after major intestinal resection is dependent on luminal nutrition and pancreaticobiliary secretions. Recent evidence, however, suggests that humoral mechanisms, e.g., gastrin or enteroglucagon, may also play a part in this process. A 75% proximal small bowel exclusion was performed in 16 male Wistar rats and the excluded bowel was fashioned into a Thiry-Vella fistula. Half of the animals were allowed food ad libitum, while the rest were fed intravenously. The animals were killed at 12 days, and plasma, gastrin, and enteroglucagon were measured, while cell proliferation was determined by measuring the crypt cell production rate employing a stathmokinetic method using vincristine and crypt microdissection. In addition to these animals, 16 rats had a jejunal transection only, with half of these animals nourished intravenously, while the remainder were allowed food ad libitum. In the Thiry-Vella rats, plasma enteroglucagon was greater with oral feeding (566 +/- 59 pmol/L) than with intravenous feeding (120 +/- 452 pmol/L) (p less than 0.01), but gastrin levels did not differ in the two groups. In the ileum in continuity, crypt cell production rate per hour was greater in the orally fed animals (52 +/- 8) compared with the intravenously fed group (18 +/- 5) (p less than 0.001). In the excluded fistula, crypt cell production rate per hour was reduced by 23.8 +/- 2 in orally fed rats, but this was greater than in the intravenously fed group (16 +/- 1.5) (p less than 0.01). Both orally and intravenously fed transected rats had significantly lower plasma hormone levels, and reduced crypt cell production rate compared with the respective Thiry-Vella groups. This study suggests a distinct role for a humoral agent responsible for the proliferative changes seen after small bowel resection, and in this respect enteroglucagon appears more relevant than gastrin.

Fetal and maternal endocrine responses to exercise in the pregnant ewe

Maternal and fetal concentrations of plasma insulin, pancreatic glucagon, growth hormone (GH), corticosteroids and enteroglucagon, and of blood glucose and lactate, were measured in well-fed, late pregnant ewes before, during and after walking on a treadmill at 0.7 m.s-1, 10 degrees slope for 60 min. Exercise caused rapid and substantial increases in maternal concentrations of glucose, lactate, pancreatic glucagon and corticosteroids, smaller but significant decreases in levels of GH and enteroglucagon, and no change in insulin. With the exception of GH, concentrations of these maternal hormones had returned to pre-exercise levels within 20 min of stopping exercise. The exercise-induced maternal hyperglycaemia was associated with a proportionately similar, rapid increase in fetal blood glucose; fetal blood lactate and plasma corticosteroids also increased, but at slower rates and other fetal hormone concentrations were unchanged. During recovery there was a rapid increase in fetal insulin levels. The results are discussed in terms of the regulation of exercise-induced changes in maternal energy metabolism, and fetal metabolic and hormonal sensitivity to these changes.

Enteroglucagon and GIP after oral glucose in patients with prolactinoma and acromegaly

We have performed oral glucose tolerance tests (OGTT) in nine patients with prolactinomas, eight patients with active acromegaly, five patients with acromegaly in remission and nine normal controls, and measured blood glucose, plasma insulin, pancreatic glucagon, enteroglucagon, gastric inhibitory polypeptide (GIP) and GH during the test. Patients with prolactinomas and with active acromegaly were hyperinsulinaemic and five of the nine patients with prolactinomas had impaired glucose tolerance, with blood glucose levels that were significantly higher than the normal controls. Prolactinoma patients had higher GIP levels than those with active acromegaly and both showed a failure of suppression of pancreatic glucagon. Of particular interest was the finding that enteroglucagon, a putative gut growth factor, was low in active acromegaly when compared with acromegaly in remission, but similar to normal in the rest of the patients.

Plasma enteroglucagon and neurotensin in infantile pyloric stenosis

Plasma concentrations of gastrin, somatostatin, neurotensin, and enteroglucagon were measured by radioimmunoassay in normal 30- and 45-day-old neonates and age-matched infants with confirmed idiopathic hypertrophic pyloric stenosis. Plasma gastrin and somatostatin concentrations were similar in both groups, whereas neurotensin and enteroglucagon were significantly lower in the pyloric stenosis group.

Gut hormone profile and gastric emptying in the dumping syndrome. A hypothesis concerning the pathogenesis

Insulin, enteroglucagon, neurotensin, gastric inhibitory polypeptide (GIP), and motilin have been measured in plasma during an oral glucose test in 76 patients before or after different upper gastrointestinal operations for peptic ulceration. The patients were divided into three clinical groups in accordance with their spontaneous symptoms of dumping after ordinary meals: 26 postoperative patients into a dumping group, 30 postoperative patients into a non-dumping group, and 20 preoperative patients into a reference group. The fasting values of the five hormones were similar in the operated and non-operated groups. Insulin, enteroglucagon, neurotensin, and GIP rose significantly in all patients. The increment of insulin, enteroglucagon, and neurotensin was greater in the postoperative patients with dumping symptoms than in the postoperative and preoperative patients without dumping symptoms. All the patients had a small decrement of motilin. The resulting hypothesis is that an impaired neural control of the gastric emptying is the essential aetiological factor in the dumping syndrome. The excessively rapid delivery of the meal into the jejunum is the abnormal stimulus to the exaggerated hormone release. The response of the small intestine with regard to the hormone release is considered proportionate to the given stimulus. The abrupt fall in circulating blood volume is suggested to play a role in producing the polymorphic symptoms. Neurotensin and GIP cannot be excluded from being the factors arresting the rapid gastric emptying in patients whose neural control has been impaired after gastric surgery.

Ileal enteroglucagon cells after ileal-duodenal transposition in the rat

The changes occurring in the ileal wall and in enteroglucagon cells were studied in a rat model of intestinal adaptation, obtained by the transposition of a segment of distal ileum into the mid-duodenum (6 rats, compared with 6 transected controls). After 40 days, the transposed ileal segment, compared to the equivalent segment in the controls, showed striking increase in weight, especially of the epithelium (1,585 +/- 127 vs. 305 +/- 42 mg, mean +/- SEM, p less than 0.0005). The calculated weight of enteroglucagon cells in the segment showed a smaller, but significant increase (1.7 +/- 0.3 vs. 0.8 +/- 0.2 micrograms, p less than 0.05). Plasma enteroglucagon was markedly raised (239 +/- 28 vs. 61 +/- 7.1 pmol/l, p less than 0.0005) and showed a greatly increased meal-stimulated response (1,521 +/- 284 vs. 83 +/- 43 pmol, p less than 0.0005), thus suggesting hyperactivity of enteroglucagon cells.

Diurnal profile of pancreatic polypeptide, pancreatic glucagon, gut glucagon and insulin in human morbid obesity

The diurnal profiles of pancreatic glucagon, insulin, pancreatic polypeptide (PP), and enteroglucagon were studied in five obese non-diabetic subjects (195 +/- 11 per cent of ideal body weight) and in six age matched controls. All the subjects were served with ordinary mixed meals five times during the day. The obese subjects were normoglycemic but hyperinsulinemic. Both groups showed rapid increases in PP to all meals, but the PP-response was significantly impaired in the obese group during the first part of the day. Normal subjects showed significant enteroglucagon responses to all meals, and had elevated levels throughout the day. In obese subjects, levels and responses were much lower at all times. Pancreatic glucagon profiles were similar. It is concluded that the possible role of abnormalities of PP and enteroglucagon secretion in the pathogenesis of human obesity deserves further study.

Gut and pancreatic hormones after jejunoileal bypass with 3:1 or 1:3 jejunoileal ratio

The aim of the study was to elucidate the differential role of the jejunum and ileum in the regulation of secretion of the gut hormones, gastrin, gastric inhibitory polypeptide, and enteroglucagon, and the pancreatic hormones, insulin, glucagon, and pancreatic polypeptide, in man. We measured the plasma levels of the hormones (and glucose) during fasting and after a test meal in 34 obese patients, of whom 5 were waiting for bypass surgery and 29 had had a jejunoileal bypass with a 3:1 or 1:3 jejunoileal ratio between the functioning segments 3, 9, or 15 months earlier. The major findings were that surgery bypass (1) has no important influence on the levels of gastrin and pancreatic polypeptide, (2) reduces the level of gastric inhibitory polypeptide, insulin (and glucose), and enhances the pancreatic glucagon level, independently of the jejunoileal ratio, and (3) increases enteroglucagon secretion, most effectively so with a short jejunal and long ileal segment left in continuity. These findings suggest that the upper jejunum and terminal ileum has no important role in regulation of secretion of these hormones apart from that in secretion in enteroglucagon which is related to the length of functioning ileum.

Hormonal and metabolic effects of intravenous infusion of prostacyclin in healthy women

To study the hormonal and metabolic effects of prostacyclin (PGI2), 6 healthy women were infused iv with PGI2 (1, 2, 4, and 8 ng/kg/min. each for 20 min) dissolved in glycine buffer, or with glycine buffer only. Serial blood samples collected before, during and after the infusion were assayed for FSH, LH, prolactin, growth hormone, thyrotrophin, oestradiol, progesterone, testosterone, cortisol, thyroxine, triiodothyronine, renin, aldosterone, glucose, insulin, glucagon, cholesterol, high density lipoprotein-cholesterol, triglycerides, alkaline phosphatase, alanine and aspartate aminotransferases, bilirubin, sodium, potassium, chloride, calcium, inorganic phosphorous, creatinine and uric acid. PGI2 infusions were accompanied by increased levels of prolactin, growth hormone and cortisol, probably due to the stressful side-effects during PGI2 infusion. In addition, plasma renin activity, glucagon and blood glucose increased, whereas the other variables measured did not change. These PGI2-effects should be kept in mind, when PGI2 is used in clinical practice.

Gut hormone release after intestinal resection

To investigate the possible role of gut and pancreatic hormones in the adaptive responses to gut resection, plasma concentrations of the circulating hormones were measured, in response to a test breakfast, in patients with either small or large intestinal resection and in healthy control subjects. In 18 patients with partial ileal resection a significant threefold rise was found in basal and postprandial levels of pancreatic polypeptide, a fourfold increase in motilin, and more than a twofold increase in gastrin and enteroglucagon levels compared with healthy controls. In contrast, nine patients with colonic resection had a threefold rise in levels of pancreatic polypeptide only. One or more of these peptides may have a role in stimulating the adaptive changes found after gut resection.

The correlation between gastric emptying time and the response of GIP and enteroglucagon to oral glucose in duodenal ulcer patients

Simultaneous 50-g oral glucose tolerance tests and measurements of gastric emptying time were performed in 11 duodenal ulcer patients. Gastric emptying time, measured by the gamma-camera technique, and the response of gastric inhibitory polypeptide (GIP) and enteroglucagon to the oral load showed a significant negative correlation. The GIP response and the insulinogenic index were significantly positively correlated. It is concluded that the increased GIP and insulin response to glucose among duodenal ulcer patients may be explained by increased gastric emptying, known to occur in these patients. The study has not given new information on the possible physiological role of enteroglucagon.

Feeding and the development of enteroinsular hormone secretion in the preterm infant: effects of continuous gastric infusions of human milk compared with intermittent boluses

Preterm infants receive gastric milk feeds as continuous infusions or intermittent boluses. It is not known whether these feeding methods have different effects on the development of digestive metabolism. We have measured plasma levels of insulin, pancreatic polypeptide (PP), gastric inhibitory polypeptide (GIP), gastrin, motilin, enteroglucagon (EG) and neurotensin (NT) in 19 preterm infants (28-34 weeks gestation) tolerating full enteral feeding from birth. 7 infants received human milk by continuous infusion, 12 infants were bolus fed. Hormones were measured in cord blood and at 6 and 13 days of age; samples were drawn preprandially in bolus fed infants. Both groups showed similar significant increases in plasma motilin, PP, NT and EG levels. At 13 days infusion fed infants had higher insulin. GIP and gastrin levels. No difference in rate of weight gain was seen in the two groups of infants. We conclude that both methods of feeding induce progressive changes in circulating enteroinsular hormone levels. However, the endocrine milieu is different in the two groups, particularly since bolus-fed infants experience marked cyclical surges in hormones after boluses of milk by 13 days of age. These differences in hormone release may affect metabolic homeostasis.

Pancreatic and gastrointestinal hormones in chronic pancreatitis

Pancreatic and gut hormones have been measured in 39 patients with chronic pancreatitis, 16 of whom had severe pancreatic insufficiency. Patients with pancreatic insufficiency had significantly diminished fasting levels and postprandial rises of pancreatic polypeptide which were less than 20% of normal. Patients with chronic pancreatitis, with or without exocrine insufficiency, had two- to threefold higher plasma levels of motilin and enteroglucagon than controls. Plasma levels of insulin, pancreatic glucagon, gastric inhibitory polypeptide and gastrin were similar to normal in these patients. The pattern of response of these hormones to a test breakfast differs markedly from those seen in other gut disease states and may reflect pathophysiological mechanisms.

Postnatal surges in plasma gut hormones in term and preterm infants

Using sensitive radioimmunoassays we have measured and compared plasma concentrations of motilin, gastrin, enteroglucagon, neurotensin, gastric inhibitory polypeptide and pancreatic polypeptide in (a) 53 healthy, preterm infants at birth or preprandially at 2.5, 6, 13 or 24 days; (b) 45 normal, breast-fed, term infants at birth or preprandially at 6 or 16 days, and (c) 12 healthy fasting adults. Plasma concentrations of all six hormones rose during the neonatal period in both preterm and term infants, the first four of these hormones reaching levels which exceeded those seen in healthy fasting adults. The rate of increase and the magnitude of the changes were less in term infants than preterm infants. These changes in plasma hormone concentrations may be the result of enteral feeding. Gut hormones exert important effects on gut growth, secretion and motility and on intermediary metabolism, and the postnatal hormonal surges observed may play a key role in the postnatal adaptions to enteral feeding.

A qualitative comparison of canine plasma gastroenteropancreatic hormone response to bombesin and the porcine gastrin-releasing peptide (GRP)

The effect on plasma gastroenteropancreatic hormone levels on infusing the porcine gastrin-releasing peptide and bombesin into dogs demonstrated no qualitative difference in the spectrum of activity of the two peptides. Sustained elevation in plasma immunoreactive gastrin, pancreatic polypeptide, enteroglucagon, gastric inhibitory polypeptide, pancreatic glucagon and transient elevations in plasma insulin were seen during infusions of both peptides. The similar spectrum of activities and the structural homology between the two peptides suggests that the porcine gastrin releasing peptide is the porcine counterpart of the amphibian peptide bombesin.

[Behavior of plasma enteroglucagon and neurotensin in obese patients subjected to biliopancreatic bypass]

Biliopancreatic bypass for obesity entails a 2/3 distal gastrectomy with Roux-en-Y reconstruction, being the small bowel transected at its midpoint and the enteroenteroanastomosis place 50 cm proximal to the ileocecal valve. Neurotensin and enteroglucagon fasting and meal-stimulated plasma concentrations were determined in 13 nonobese healthy volunteers, in 13 nonoperated obese patients, in 11 subjects within two months, in 12 subjects four to twelve months and in 7 subjects fifteen to twenty months after operation. Basal plasma enteroglucagon was significantly higher in the obese group than in the controls. However, there was no difference in the peak response, and a decrease, though not statistically significant, was seen in the integrated response. All three values were strikingly augmented in the 0-2 month group, with a highly significant difference from the preoperative group. The 4-12 and 15-20 month groups, in comparison with the 0-2 month group, showed no changes in fasting levels, a clear-cut decreased peak response and a sharp progressive reduction in integrated response, mean value in the 15-20 month group being significantly lower than that of 0-2 month group. Neurotensin basal and meal-stimulated peak plasma concentrations in the obese group were significantly higher than in the control group, whilst the integrated response was almost identical in the two groups. In postoperative groups no substantial changes in fasting levels and an increase in the peak response were observed, with a considerable progressive rise in the integrated response.

Elevation of plasma neurotensin in the dumping syndrome

1. The pathophysiology of the dumping syndrome is poorly understood. Plasma levels of four small intestinal hormones have been measured after an oral glucose provocation test in 19 patients with dumping symptoms and in matched controls. 2. Plasma levels of neurotensin, a newly discovered highly potent, hypotensive ileal peptide, were significantly increased in symptomatic patients compared with those of controls [20 min rise of 43 +/- 6.0 (mean +/- SEM) pmol/l in 19 symptomatic patients, 8.0 +/- 5.5 pmol/l in 20 postoperative symptom-free patients, and 4.1 +/- 3.5 pmol/l in 20 pre-operative patients with duodenal ulcer, P < 0.01]. 3. The rise in enteroglucagon was greater than normal but of similar magnitude to that seen in several other gastrointestinal conditions not associated with dumping symptoms. 4. The release of both gastric inhibitory peptide and motilin did not differ significantly from that of controls.

Development of gut hormone responses to feeding in neonates

The development of the effects of a human milk feed on plasma concentrations of motilin, neurotensin, gastric inhibitory polypeptide, enteroglucagon, gastrin, and secretin were studied in 158 healthy preterm neonates (mean gestation 33 1/2 weeks) at mean postnatal ages of 2 1/2, 6, 13, or 24 days. Pronounced progressive changes occurred in postprandial hormone responses; these were absent or small in the first days of life and were large by age 24 days. These changes may have important consequences in the adaptation to postnatal life.

Plasma motilin, gastrin, and enteroglucagon and feeding in the human newborn

Plasma concentrations of motilin, gastrin, and enteroglucagon were measured in cord blood and during the first 24 days of life before feeding in 45 term and 63 preterm, healthy infants. Levels of these hormones rose steeply after birth, reaching concentrations that were much higher than those in fasting adults. These increases in hormone concentration were not present in a group of 10 preterm infants who had received only intravaenous dextrose from birth because of hyaline membrane disease. Our findings suggest that early enteral feeding may trigger the postnatal increase in plasma concentrations of gut hormones and that this could play an important role in the physiologaical adaptations to extrauterine nutrition.

Immunoreactive glucagon and insulin C-peptide in man after resection of the pancreas and total pancreatectomy

Pancreatic-type glucagon (PTG) has been found in the plasma of totally pancreatectomized human beings. Arginine infusion, however, caused no increase in PTG. Pancreas-resected patients had a normal response of PTG to arginine and a subnormal increase in C peptide. Gut glucagon-like immunoreactants (gut GLI) were increased in resected patients and further increased in totally pancreatectomized patients. Gut GLI showed no change during arginine stimulation.

Simultaneous recording of the gastro-entero-pancreatic hormonal peptide response to food in man

The serum or plasma concentrations of gastrin, gastric inhibitory polypeptide (GIP), gut glucagon-like-immunoreactivity (gut GLI), secretin, vasoactive intestinal polypeptide (VIP), insulin, glucagon, and pancreatic polypeptide (PP) were recorded simultaneously following the ingestion of a normal, mixed meal in seven healthy, normal weight men. The concentrations of PP and gastrin increased within 10 min. Subsequently GIP, insulin, glucagon, and gut GLI increased in the order mentioned. The mean concentrations of secretin and VIP were not affected by the meal, athough transient decreases in secretion concentrations could be detected in all subjects. The concentrations of the other hormones remained elevated for 4 hr or more. Perhaps the period of observation following food stimulation of gastro-entero-pancreatic hormones should be extended.

Improved glucose tolerance four hours after taking guar with glucose

To gain some insights about the possible cumulative metabolic effect after a high-fibre meal, 6 subjects took two 80 g oral glucose loads, 4 h apart. Addition of 22.3 g guar to the first load decreased the rise in blood glucose and insulin after the second (guar-free) load by 50% (p less than 0.002) and 31% (p less than 0.02) respectively. This corresponded with decreased 3-hydroxybutyrate levels at the start of the glucose tolerance test after guar (by 20%, p less than 0.02). When no guar was added to the first glucose load, both 3-hydroxybutyrate and non-esterified fatty acids tended to rise before the second test. No significant effect was seen in the responses of the gut hormones, gastric inhibitory peptide and enteroglucagon. Spreading the intake of the first 80 g of glucose over the initial 4 h (2 subjects) similarly flattened the glycaemic but increased the insulin response. The effect of guar on carbohydrate and fat metabolism, therefore, lasts at least 4 h and may result in improved carbohydrate tolerance to subsequent guar-free meals.

Combined use of guar and acarbose in reduction of postprandial glycaemia

Symptoms associated with carbohydrate malabsorption limit the usefulness to diabetics of a powerful glycoside-hydrolase inhibitor (acarbose) which reduces postprandial glycaemia. Addition of a low dose (50 mg) of a acarbose together with 14.5 g guar gum to a breakfast test meal taken by 8 healthy volunteers reduced the mean peak rise in blood-glucose at 30 min by 70%. Areas under the insulin and gastrointestinal-polypeptide response curves were also greatly reduced. No evidence of carbohydrate malabsorption, as assessed by measurement of breath hydrogen, was found during any of the test periods. When acarbose was taken alone, 3 of the 8 subjects had troublesome symptoms and the 30 min rise in blood-glucose was reduced by only 28%. Thus, combination of these two agents effectively reduces the rate of carbohydrate absorption without increasing side-effects and may make combined acarbose and guar acceptable in the management of some diabetics.

How concentrate feeding affects glucoregulatory hormones in ruminants: implications in bovine ketosis

Twenty-four feedlot steers and four sheep were fed roughage or grain rations while three other sheep received intraduodenal infusions of amino acids, glucose, volatile fatty acids, and proteins to determine whether the release of plasma glucagon-like immunoreactivity is influenced by dietary factors and the composition of duodenal chyme. Plasma glucagon-like immunoreactivity rose in both cattle and sheep as the proportion of grain in their rations was increased. In response to intraduodenal infusions, only glucose stimulated glucagon-like immunoreactivity release. These experiments demonstrate that plasma glucagon-like immunoreactivity concentrations change in cattle and sheep in response to the amount of grain consumed and that glucagon-like immunoreactivity release is triggered by glucose in intestinal chyme.

The effect of feeds of differing composition on entero-insular hormone secretion in the first hours of life in human neonates

Little is known on the enteral stimuli for gastro-intestinal hormone release in newborn infants. We have compared the effect of the first feed of human breast milk (5 ml/kg) or 10% dextrose (5 ml/kg) on blood glucose and plasma gastrin, enteroglucagon, Gastric Inhibitory polypeptide (GIP), pancreatic glucagon, and insulin in 21 full-term infants at 4--6 hours of age. The first feed of human milk caused a rise in blood glucose and plasma insulin, gastrin and enteroglucagon, but no change occurred in GIP or pancreatic glucagon. The 10% dextrose feed did not stimulate enteroglucagon release, although similar changes occurred in blood glucose and plasma insulin and gastrin. We conclude that the composition of the feed influences the pattern of gastro-intestinal hormone release during the first hours of life and that the entero-insular responses to feeding differ in the neonate and the adult.

Plasma enteroglucagon after jejunoileal bypass with 3:1 or 1:3 jejunoileal ratio

Enteroglucagon concentration in peripheral blood was determined before and after a test meal in 24 morbidly obese patients. Eighteen had jejunoileal bypass, 6 with a 3:1 and 12 with a 1:3 jejunoileal ratio of the functioning segment, and 6 were unoperated. All three groups exhibited an increment of enteroglucagon concentration after the meal. Both the fasting values and the postprandial integrated increments were higher in operated patients than in unoperated patients and higher after 1:3 bypass than after 3:1 bypass. The findings agree with the hypothesis that enteroglucagon secretion is stimulated by exposure of the lower bowel to upper-bowel content, and that the effect of enteroglucagon is, as seen after bypass operation, stimulation of growth and reduction of motility of the intestine.

Fat-induced jejunal inhibition of gastric acid secretion and release of pancreatic glucagon, enteroglucagon, gastric inhibitory polypeptide, and vasoactive intestinal polypeptide in man

The effect of intrajejunal (i.j.) infusion of fat on meal-stimulated gastric acid secretion and release of pancreatic glucagon (PG), enteroglucagon (EG), gastric inhibitory polypeptide (GIP), and vasoactive intestinal polypeptide (VIP) was studied in seven healthy volunteers. I.j. fat markedly inhibited meal-stimulated acid secretion as compared to a control study with i.j. saline infusion. The acid inhibition was accompanied by augmental plasma concentrations of EG, GIP, and VIP but not of PG, suggesting that EG, GIP, and VIP may be among mediators of fat-induced jejunal inhibition of acid secretion. Concentration-time relationship makes it unlikely that the observed inhibition could be ascribed to any single peptide studied.

Metabolic and endocrine events at the time of the first feed of human milk in preterm and term infants

The first feed of breast milk given to a group of 12 term infants was previously shown to increase the levels of blood glucose and plasma insulin, growth hormone (GH), gastrin, and enteroglucagon. We have now studied the effects of the first feed of breast milk in two similar groups of preterm infants, to compare the results with those obtained for the term infant. One group of 8 preterm infants received a bolus (2.5 ml/kg) of breast milk via a nasogastric tube; the other group of 5 infants received a continuous intragastric infusion (2.5 ml/kg per hour) of breast milk. No change occurred in the concentrations of blood glucose, lactate, pyruvate, or ketone bodies, or in plasma insulin, GH, pancreatic glucagon, or enteroglucagon in either the 'bolus fed' or the 'infusion fed' group of preterm infants. Thus the marked metabolic and endocrine changes in term infants after the first feed do not occur in preterm infants with standard methods of feeding.