The effect of acute dual SGLT1/SGLT2 inhibition on incretin release and glucose metabolism after gastric bypass surgery.

Enhanced meal-related enteroendocrine secretion, particularly of glucagon-like peptide-1 (GLP-1), contributes to weight-loss and improved glycemia after Roux-en-Y gastric bypass (RYGB). Dietary glucose drives GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) secretion postoperatively. Understanding how glucose triggers incretin secretion following RYGB could lead to new treatments of diabetes and obesity. In vitro, incretin release depends on glucose absorption via sodium-glucose cotransporter 1 (SGLT1). We investigated the importance of SGLT1/SGLT2 for enteropancreatic hormone concentrations and glucose metabolism after RYGB in a randomized, controlled, crossover study. Ten RYGB-operated patients ingested 50 g of oral glucose with and without acute pretreatment with 600 mg of the SGLT1/SGLT2-inhibitor canagliflozin. Paracetamol and 3-O-methyl-d-glucopyranose (3-OMG) were added to the glucose drink to evaluate rates of intestinal entry and absorption of glucose, respectively. Blood samples were collected for 4 h. The primary outcome was 4-h plasma GLP-1 (incremental area-under the curve, iAUC). Secondary outcomes included glucose, GIP, insulin, and glucagon. Canagliflozin delayed glucose absorption (time-to-peak 3-OMG: 50 vs. 132 min, P < 0.01) but did not reduce iAUC GLP-1 (6,067 vs. 7,273·min·pmol-1·L-1, P = 0.23), although peak GLP-1 concentrations were lowered (-28%, P = 0.03). Canagliflozin reduced GIP (iAUC -28%, P = 0.01; peak concentrations -57%, P < 0.01), insulin, and glucose excursions, whereas plasma glucagon (AUC 3,216 vs. 4,160 min·pmol·L-1, P = 0.02) and amino acids were increased. In conclusion, acute SGLT1/SGLT2-inhibition during glucose ingestion did not reduce 4-h plasma GLP-1 responses in RYGB-patients but attenuated the early rise in GLP-1, GIP, and insulin, whereas late glucagon concentrations were increased. The results suggest that SGLT1-mediated glucose absorption contributes to incretin hormone secretion after RYGB.

Pancreatic polypeptide: a review of its involvement in neuro-endocrine reflexes, islet-acinar interactions and ethanol-evoked physiopatologic pancreatic gland changes.

prevents, in pancreocytes, the evolving of a "supramaximalecbolic-stimulation" process. The PP involvement as a modulating agent of pancreon's reactivity is reflected by the progressive increment of its plasma values in the first week of an evolving AP episode. In the AP associated to a large meal, an overpowering of the pancreon's brake might have a pivotal role. In experimental and clinical chronic alcoholism, a vagal neuropathy of the Pavlov inhibitory fibers that, as a consequence, impairs the pancreon's brake through a depression of PP secretion is at the basis of an enhanced reactivity of the duodeno-pancreatic reflexes. The latter leads to intrapancreatic cholinergic hypertonus and to Vater papilla's dysfunction. These changes, plus an enhanced pancreocyte's response to CCK, are at the core of acinar cell "supramaximal stimulation" with the organelle disruption that process implies. The intrapancreatic cholinergic hypertonus, the enhanced exocrine cell reactivity to CCK stimulation, and the augmented resistance to the pancreatic secretion flow at Oddi sphincter, explain the aggravating influence of chronic alcoholism on an episode of acute biliary pancreatitis. As the PP secretion, normally elicited by secretin, CCK, food and insulin hypoglycemia, is depressed in the presence of an augmented number of PP cells, as it is in the cases of chronic alcoholics, cystic fibrosis patients and, also, in dogs with pancreatic fibrosis (ductal ligation), it has been inferred, besides our postulated impairment of the Pavlov inhibitory fibers in the vagus nerves, that the defect of PP release is localized to the common final pathway of the above stimuli, probably in or near the PP cell itself This review was prompted by the unexpected experimental finding in canines that Tissucol-induced pancreatic ductal blockade elicits Pancreatic Polypeptide (PP) release and seems to be at the basis of the beneficial effects on taurocho- late-induced acute pancreatitis (AP). In the release mechanism of this regulatory peptide secreted by PP cells located in the periphery of Langerhans islets and scattered in the ductal epithelium, two neuroendocrine reflexes (NER) are involved. The "short" NER is evoked from the duodenum by an unknown component of bile-pancreatic secretion. The "long" NER is triggered by a vagovagal reflex. PP induces a depression of the intrapancreatic cholinergic tone. On the one hand suppressing, hormonally, nervous impulses discharge from the vagal nuclear complex in the brainstem. On the other, interfering paracrinically on the cholinergic transmission by acting, presynaptically, on post-ganglionic cholinergic neurons. The resulting PP-evoked fall of the intrapancreatic cholinergic tone depresses the hormone induced (secretin, CCK) pancreons secretory response. PP, with other agents, contributes to the "fail-safe" system or pancreon's brake that

Gut hormones as peripheral anti obesity targets.

Many peptides are synthesised and released from the gastrointestinal tract. Whilst their roles in regulation of gastrointestinal function have been known for some time, it is now evident that they also influence eating behaviour and thus potential anti obesity targets. Peptide YY (PYY) is released post prandially from the gastrointestinal L-cells with glucagon-like peptide 1 (GLP-1) and oxyntomodulin. Following peripheral administration of PYY 3-36, the circulating form of PYY, to mouse, rat or human there is marked inhibition of food intake. PYY 3-36 is thought to mediate its actions through the NPY Y2 GPCR. Obese subjects have lower basal fasting PYY levels and have a smaller post prandial rise. However, obesity does not appear to be associated with resistance to PYY (as it is with leptin) and exogenous infusion of PYY 3-36 results in a reduction in food intake by 30% in an obese group and 31% in a lean group. GLP-1 or oxyntomodulin, products of the prepreglucagon gene, decrease food intake when administered either peripherally or directly into the CNS. In addition, both have been shown to decrease food intake in humans. These effects are thought to be mediated by the GLP-1 receptor. Ghrelin, a huger hormone produced by the stomach, increases in the circulation following a period of fasting. Administration of ghrelin either peripherally or directly into the CNS increases food intake and chronic administration leads to obesity. Further infusion into normal healthy volunteers increases both food intake and appetite. Ghrelin is thought to act through the growth hormone secretagogue receptor (GHS-R). Obesity is the current major cause of premature death in the UK, killing almost 1000 people a week. Worldwide its prevalence is accelerating. The administration of the naturally occurring gut hormone may offer a long-term therapeutic approach to weight control. Here we consider the therapeutic potential of some gut hormones, and the GPCR's through which they act, in the treatment of obesity.

Impact of nocturnal hypoglycemia on hypoglycemic cognitive dysfunction in type 1 diabetes.

To test the hypothesis that glycemic thresholds for cognitive dysfunction during hypoglycemia, like those for autonomic and symptomatic responses, shift to lower plasma glucose concentrations after recent antecedent hypoglycemia in patients with type 1 diabetes mellitus (T1DM), 15 patients were studied on two occasions. Cognitive functions were assessed during morning hyperinsulinemic stepped hypoglycemic clamps (85, 75, 65, 55, and 45 mg/dl steps) after, in random sequence, nocturnal (2330-0300) hypoglycemia (48 +/- 2 mg/dl) on one occasion and nocturnal euglycemia (109 +/- 1 mg/dl) on the other. Compared with nondiabetic control subjects (n = 12), patients with T1DM had absent glucagon (P = 0.0009) and reduced epinephrine (P = 0.0010), norepinephrine (P = 0.0001), and neurogenic symptom (P = 0.0480) responses to hypoglycemia; the epinephrine (P = 0.0460) and neurogenic symptom (P = 0.0480) responses were reduced further after nocturnal hypoglycemia. After nocturnal hypoglycemia, in contrast to nocturnal euglycemia, there was less deterioration of cognitive function overall (P = 0.0065) during hypoglycemia based on analysis of the sum of standardized scores (z-scores). There was relative preservation of measures of pattern recognition and memory (the delayed non-match to sample task, P = 0.0371) and of attention (the Stroop arrow-word task, P = 0.0395), but not of measures of information processing (the paced serial addition task) or declarative memory (the delayed paragraph recall task), after nocturnal hypoglycemia. Thus, glycemic thresholds for hypoglycemic cognitive dysfunction, like those for autonomic and symptomatic responses to hypoglycemia, shift to lower plasma glucose concentrations after recent antecedent hypoglycemia in patients with T1DM.

Cholestyramine influences meal-stimulated pancreaticobiliary function and plasma cholecystokinin independent of gastric emptying and food digestion.

BACKGROUND: Cholestyramine enhances gallbladder emptying and plasma cholecystokinin responses to oral ingestion of a mixed meal. It is not known whether this effect occurs independently of alterations in gastric emptying or maldigestion of nutrients. METHODS: We perfused 15 g of an amino acid meal intraduodenally for 60 min in seven healthy volunteers, once with and once without cholestyramine. Intraduodenal perfusion of saline with or without cholestyramine (6 g/h) was started 60 min before the amino acid meal and continued for 2 h. RESULTS: Cholestyramine markedly enhanced the incremental plasma cholecystokinin response to the meal from 36 +/- 12 to 139 +/- 25 pmol/l x 60 min (P < 0.005), incremental amylase output from 2.4 +/- 0.7 to 5.7 +/- 0.7 kU/h (P < 0.05), and incremental integrated gallbladder contraction from 1948 +/- 235 to 2840 +/- 189% x 60 min (P < 0.05). CONCLUSION: The enhancing effect of cholestyramine on postprandial gallbladder contraction, pancreatic enzyme secretion, and plasma cholecystokinin release is not dependent on gastric emptying rates or appropriate digestion of nutrients.

Effects of ethanol on meal-stimulated secretion of pancreatic polypeptide and cholecystokinin: comparison of healthy volunteers, heavy drinkers, and patients with chronic pancreatitis.

Tiscornia and Dreiling (Physiopathogenic Hypothesis of Alcoholic Pancreatitis: Supranormal Ecbolic Stimulation of the "Pancreon" Units Secondary to the Loss of the Negative Component of Pancreas Innervation. Pancreas 1987;2:604-612.) proposed that hypertonicity of intrapancreatic cholinergic neurons provoked by chronic alcoholism may contribute to the pathogenesis of chronic pancreatitis (CP). In the present study, the validity of this hypothesis was investigated in humans by studying the effects of atropine, cisapride, and ethanol on the meal-stimulated secretion of pancreatic polypeptide (PP) and cholecystokinin (CCK) in healthy volunteers, heavy drinkers, and CP patients. In healthy volunteers, the early phase PP response (0-40 min) to a test meal was completely blocked by atropine, whereas it was augmented by cisapride, an enhancer of acetylcholine release from cholinergic nerves. The early phase PP response to a test meal was inhibited by ethanol in healthy volunteers, whereas, in heavy drinkers, the response was augmented and the inhibition by ethanol was abrogated. In CP patients, ethanol tended to enhance the early phase PP response. Ethanol did not affect the early phase CCK response to a test meal in any group, but it significantly enhanced the late phase CCK response (40-120 min) in CP patients. These results suggest that: (i) oral ethanol may inhibit the postprandial activation of the cholinergic neural pathway to the pancreas in healthy subjects, (ii) in heavy drinkers, postprandial cholinergic tone may be augmented and become resistant to the inhibition by ethanol, and (iii) the ethanol-induced increase in the postprandial CCK response in CP patients may play some role in the pathophysiology of this disease.

[Influence of long-term human recombinant erythropoietin treatment on secretion of pancreatic polypeptide and gastrin in hemodialysed patients with chronic renal failure]. / Wplyw dlugotrwalego leczenia ludzka rekombinowana erytropoetyna na wydzielanie polipeptydu trzustkowego i gastryny u hemodializowanych chorych z przewlekla mocznica.

The study aimed to assess the influence of long-term rhu-EPO treatment on secretion of pancreatic polypeptide (PP) and gastrin. A total of 27 haemodialysed patients and nine healthy subjects were examined. Nine patients with uraemic anaemia were treated with rhu-EPO for 12 months (EPO group), while another nine patients did not receive rhu-EPO (non-EPO group), but were monitored biochemically and clinically as patients of the EPO group. The third group (HD) comparised nine haemodialysed patients with a haematocrit value > or = 30% without rhu-EPO therapy. In all subjects plasma levels of PP and gastrin were estimated before and after administration of a test meal. Patients of the EPO and non-EPO group were examined before and after 6 and 12 months of rhu-EPO therapy (EPO group) or clinical monitoring (non-EPO group) respectively, while only one test was performed in patients of the HD group and healthy subjects. Six months rhu-EPO therapy was followed by an decrease of basal plasma level of PP and increased response of gastrin to the test meal. After 12 months of rhu-EPO therapy basal plasma level of PP was still lower, the response of PP secretion to a test meal was higher, while that of gastrin secretion lower that the pretreatment ones. Our results suggest, that rhu-EPO treatment exerts effect on secretion of PP and gastrin. These alterations seem not to be related to improvement of the haematological status.

Nutrient-specific effects of modified sham feeding on pancreatic polypeptide release.

OBJECTIVE: To study the effect of meal composition on pancreatic polypeptide release during modified sham feeding. DESIGN: In random order and on separate occasions, isocaloric, isothermic, isoosmotic, homogenized meals (1050 kJ; 250 kcal) either rich in fat (walnuts; 64 g fat, 7 g protein, 15 g starch per 100 g), protein (codfish, 1 g fat, 23 g protein per 100 g) or carbohydrates (bananas; 22 g starch, 1 g protein per 100 g) were sham-fed for 30 min by tasting and spitting out the meal. The plasma pancreatic polypeptide response was monitored by radioimmunoassay at 10 min intervals from 20 min before to 120 min after modified sham feeding. SETTING: Department of Gastroenterology and Hepatology of a University Hospital. SUBJECTS: Seven healthy volunteers: 3 male, 4 female; age 45 (range 30-77) years. RESULTS: Integrated plasma pancreatic polypeptide responses to modified sham feeding of codfish (1088 +/- 395 pM*120 min; P < 0.05) and walnuts (1200 +/- 542 pM*120 min) were distinctly higher (P < 0.05) than to modified sham feeding of bananas (-390 +/- 291 pM*120 min). CONCLUSIONS: These results demonstrate that the pancreatic polypeptide response to modified sham feeding is dependent on the composition of the meal.

Regulation of pancreatic polypeptide release is mediated through M3 muscarinic receptors.

The purpose of this study was to determine the regulation of pancreatic polypeptide (PP) release by using pirenzepine (a specific M1 muscarinic receptor antagonist), 4-diphenylacetoxy-N-methylpiperidine methobromide (4-DAMP, a specific M3 muscarinic receptor antagonist), atropine (a nonspecific muscarinic receptor antagonist), and loxiglumide (cholecystokinin, CCK, receptor antagonist) in dogs. In conscious dogs with chronic gastric and duodenal fistulas, release of PP and exocrine pancreatic secretion were stimulated by constant intravenous infusion of CCK-8 (200 ng/kg/h). Graded doses of pirenzepine (0.18-4.7 mmol/kg/h), 4-DAMP (6.7-180 nmol/kg/h), or atropine (0.89-24 nmol/kg/h) dose-dependently reduced plasma PP responses to CCK-8 without influence on exocrine pancreatic secretion. ID50 calculated from these results were 492 +/- 150 nmol/kg/h for pirenzepine, 10.7 +/- 1.8 nmol/kg/h for 4-DAMP and 19.4 +/- 5.2 nmol/kg/h for atropine. A similar sequence in the inhibitory potency was observed in 2-deoxy-D-glucose (2-DG, 100 mg/kg)-stimulated PP release, exocrine pancreatic, and gastric secretions. On the other hand, loxiglumide, a CCK receptor antagonist, did not influence PP release stimulated by 2-DG. These findings suggest that both CCK- and 2-DG-stimulated PP releases are mainly under cholinergic nerve control mediated by M3 muscarinic receptor in dogs.

Effect of acute hyperglycaemia on gall bladder contraction induced by cholecystokinin in humans.

This study examined the effect of acute hyperglycaemia, induced by intravenous glucose, on gall bladder motility. Six healthy volunteers were studied in random order on three occasions during normoglycaemia and hyperglycaemia with blood glucose concentrations stabilised at 8 and 15 mmol/l. Gall bladder volumes, measured with ultrasonography, were studied before and during infusion of stepwise increasing doses of cholecystokinin (CCK-33; 0.25, 0.5, and 1.0 IDU.kg-1.h-1). Each dose was given for 30 minutes. Pancreatic polypeptide (PP) secretion was determined as an indirect measure of cholinergic tone. Infusion of CCK-33 resulted in significant dose dependent reductions in gall bladder volume in all three experiments. Compared with normoglycaemia the gall bladder contraction was significantly (p < 0.05) reduced during infusion of 0.25 and 0.5 IDU kg-1.h-1 CCK-33 in the 8 mmol/l hyperglycaemic experiment, and during infusion of 0.25, 0.5, and 1.0 IDU kg-1.h-1 CCK-33 in the 15 mmol hyperglycaemic experiment. During hyperglycaemia basal plasma PP concentrations and PP secretion in response to CCK-33 were significantly (p < 0.05) reduced. It is concluded that blood glucose concentrations affect gall bladder motility, that an acute hyperglycaemia at 8 and 15 mmol/l reduces the gall bladder responsiveness to CCK-33 in a dose dependent manner, and that hyperglycaemia reduces basal and CCK-33 stimulated plasma PP concentrations, suggesting impaired cholinergic activity during hyperglycaemia.

Erythromycin effects on gastric emptying, antral motility and plasma motilin and pancreatic polypeptide concentrations in anorexia nervosa.

In primary anorexia nervosa, gastric motility is often impaired and ensuing symptoms further discourage eating. Prokinetic agents have been shown to accelerate gastric emptying in affected patients. This study investigated whether emptying of a radiolabelled semisolid 1168 kJ meal and antral contractility were enhanced by intravenous erythromycin. Eight women and two men with anorexia nervosa (21-46 years, 50-75% of ideal body weight) received 200 mg erythromycin or placebo under crossover double blind conditions. Gastric emptying and antral contractility were recorded scintigraphically for 90 minutes. In addition, plasma motilin and pancreatic polypeptide concentrations were determined. With placebo, antral contractions were of regular 3 cycles/minute frequency. With erythromycin, less frequent and partly arrhythmic long duration contractions set in and emptying was accelerated: after 90 minutes, the activity remaining in the stomach was markedly less than with placebo in all patients (Sign test, p < 0.002). Basal motilin and pancreatic polypeptide concentrations were normal and showed a normal response to the meal in all patients. Motilin concentrations decreased slightly more and pancreatic polypeptide concentrations increased markedly more with erythromycin than with placebo, possibly because the meal reached the intestine earlier. In conclusion, erythromycin accelerated emptying markedly and in most patients induced an antral motor activity characterised by long duration contractions occurring at often irregular intervals.

Postprandial gallbladder motility and plasma cholecystokinin at regular time intervals after injection of octreotide in acromegalics on long-term treatment.

The increased risk of gallstone formation in acromegalics treated with the somatostatin analog octreotide has been related to an impaired gallbladder emptying. To determine the duration of these inhibitory effects, meal-stimulated gallbladder motility, plasma cholecystokinin (CCK), and pancreatic polypeptide (PP) were measured in five acromegalics treated for 6-32 months with 200-300 micrograms octreotide daily. Meal tests were performed 45 min, 8 hr and two weeks after the last 100-micrograms subcutaneous dose. Results were compared with those in normal subjects. Integrated postprandial gallbladder contraction (-125 +/- 194 cm3/120 min) and integrated PP secretion (-0.1 +/- 0.2 nmol/liter/120 min) were completely suppressed in the 45-min study, but significantly improved (P < 0.05) when measured 8 hr (1376 +/- 322 cm3/120 min and 3.0 +/- 1.0 nmol/liter/120 min) and two weeks (1437 +/- 263 cm3/120 min and 10.6 +/- 1.6 nmol/liter/120 min) after the last dose of octreotide. The integrated gallbladder contraction in acromegalics at 8 hr was comparable to that at two weeks and to that in normal subjects, but the integrated PP response at 8 hr was significantly smaller (P < 0.05 vs two weeks and vs normals). Integrated plasma CCK secretion at 45 min (0.13 +/- 0.06 nmol/liter/120 min) was not statistically significantly different from the response at 8 hr (0.15 +/- 0.02 nmol/liter/120 min) and from that in normal subjects, but it was significantly increased at two weeks after cessation of octreotide (P < 0.05 vs 45 min and 8 hr).(ABSTRACT TRUNCATED AT 250 WORDS)

Cholecystokinin release by gastric distension--an atropine-sensitive mechanism.

The effect of gastric distension on plasma cholecystokinin (CCK), pancreatic polypeptide (PP) and gastrin concentrations was investigated in healthy volunteers. Fundic and antral distension was achieved by balloons attached to a gastric tube and inflated with 300 and 600 ml and 100 and 200 ml of air for fundic and antral distension, respectively. Gastric juice was continuously aspirated. Fundic distension was additionally studied during a concomitant intravenous infusion of atropine (5 micrograms/kg/h) or a bolus injection of propranolol (2 mg). Fundic distension with 300 ml caused a significant increase in PP release (+17% above basal). Distension with 600 ml significantly stimulated CCK (+81%), gastrin (+31%) and PP output (+74%) over 30 min. Atropine completely blocked PP release and almost abolished CCK release, whereas gastrin output was enhanced. Propranolol did not prevent CCK release induced by fundic distension, whereas gastrin and PP responses were diminished. Antral distension did not cause any significant changes in hormone response. In conclusion, we demonstrated a gastric phase of CCK release which is atropine sensitive, but not influenced by propranolol.