Postprandial peristalsis in the human duodenum

MMC-related retroperistalsis is a cyclical phenomenon in the duodenum linked to phase III. The aim of this study was to elucidate the direction of propagation of juxtapyloric duodenal pressure waves in the postprandial state in healthy humans and to compare with the contractions in the interdigestive phase II. Antroduodenal manometry was performed in 11 healthy subjects. Individual pressure waves propagating along a 6-cm duodenal segment were analysed with respect to the proportions of antegrade and retrograde propagation in the four duodenal subsegments (D1–D2) to (D4–D5), each subsegment being 15 mm. A test meal was given 30 min after a phase III had passed and motility recording continued for 60 min after the meal. During both the first and the second 30-min period of postprandial recording the proportion of retrograde pressure waves was larger just distal to the pylorus, (D1–D2), 40% (23–68) and 50% (23–68), respectively, compared to the distal part, (D4–D5), of the duodenal segment, 29% (12–30) and 10%(10–24), respectively (P < 0.05 and 0.01). In contrast, during late phase II of the interdigestive state antegrade pressure waves predominated in all four duodenal subsegments. We conclude that in the postprandial state a high proportion of the duodenal pressure waves (40–50%) is retrograde in the immediate juxtapyloric area while antegrade contractions predominate at a distance 5–6 cm distal to the pylorus. These manometric data together with recent observations of postprandial transpyloric liquid flow, indicate that retrograde duodenogastric propelling of contents may be an important determinant for the gastric emptying rate.     

Reproducibility of antroduodenal motility during prolonged ambulatory recording

Ambulatory recording of antroduodenal manometry is a novel technique with several advantages over standard stationary manometry recording. Although the feasibility of this technique in clinical practice has been demonstrated, reproducibility of antroduodenal motility recorded by means of ambulatory manometry has not been investigated. To test whether antroduodenal motility recorded by ambulatory manometry is reproducible, we performed two 24-h ambulatory antroduodenal manometry recordings in 18 healthy subjects according to an identical protocol with a 1-week interval. Motility was recorded with a five-channel solid-state catheter. Postprandial motility was recorded after consumption of two test meals and interdigestive motility was recorded nocturnally. Postprandial antroduodenal motor characteristics were identical between the separate recordings. The number and duration of nocturnal cycles of the interdigestive migrating motor complex were also in the same range. Phase III characteristics in general were not different between the two recordings. Only minor alterations were observed in the duration of phase III motor fronts with duodenal onset and in the number of interdigestive cycles concluded by duodenal onset phase III. Parameters obtained by qualitative analysis were comparable between the two recordings. The antroduodenal motility pattern, when measured by ambulatory recording with solid state catheters under standardized conditions, is very reproducible.     

High-resolution analysis of the duodenal interdigestive phase III in humans

To study the spatial organization of the propagating pressure waves of duodenal phase III, we performed fasting antroduodenal high-resolution manometry with a 16-channel catheter in 12 healthy subjects. The phase III pressure waves diverged in an anterograde and retrograde direction from the start site of each pressure wave. The pressure waves maintained this configuration as the activity front moved distally in the duodenum. The start site of the pressure waves moved gradually to a point approximately 12 cm (median) distal to the pylorus and remained at this point for about 40% of the phase III time before moving further distally. The length of retrograde pressure wave propagation increased to 6 cm (median) as the pressure wave origin moved aborally to a point 10-14 cm distal to the pylorus, and then decreased when the origin of pressure waves reached the distal end of the duodenum. Bidirectional pressure waves dominated in both retrograde and anterograde activity fronts. Three pressure-wave mechanisms behind the duodenal phase IV were observed. Isolated pyloric pressure waves were absent during late duodenal phase III retroperistalsis. Thus, a number of new features of the duodenal phase III-related motility were observed using high-temporospatial resolution recordings.     

Phase III of the migrating motor complex: associated with endogenous xenin plasma peaks and induced by exogenous xenin

Xenin, a recently discovered peptide produced by specific endocrine cells of the duodenal mucosa, has shown exocrine, endocrine and motility effects in the gastroenteropancreatic system in animal experiments. The aim of the present investigation was to study the role of xenin in the regulation of duodenojejunal motility of humans. Twenty-nine healthy volunteers from the hospital staff gave informed consent to participate in this investigation. In 20 volunteers, we determined plasma concentrations of immunoreactive xenin at 15 min intervals over a mean time period of 8 h fasting and recorded the interdigestive motor activity of the duodenojejunum. In a double-blind randomized crossover study on other nine subjects, synthetic xenin in a dose of 4 pmol kg-1 min-1 or placebo was infused for 10 min intravenously in the interdigestive period and postprandially after a liquid meal. Duodenojejunal motility was recorded simultaneously. Predefined interdigestive xenin plasma peaks were found to be significantly associated with the phases III of the migrating motor complex. In the interdigestive period, xenin induced a premature phase III activity in each volunteer; this was followed by a second phase III in five out of nine subjects. In the postprandial state, xenin significantly increased contraction frequency and the percentage of aborally propagated contractions. These findings suggest a role of the peptide hormone xenin in modulating interdigestive and postprandial duodenojejunal motility in humans.     

GLP-1 regulates gastroduodenal motility involving cholinergic pathways

Abstract  The gut-born incretin hormone glucagon-like peptide-1 (GLP-1) delays gastric emptying. To elucidate the mechanisms by which GLP-1 affects gastroduodenal motility and glycaemia, we studied the effects of exendin(9–39), a potent GLP-1 receptor antagonist, on gastroduodenal motility and pancreatic hormones. In this randomized, double-blind, placebo-controlled, four-arm, cross-over trial, 10 healthy volunteers were studied during the interdigestive period followed by duodenal perfusion of a mixed liquid meal (250 kcal). On four separate days, exendin(9–39), atropine, exendin(9–39) + atropine or saline were infused intravenously. Antro-pyloro-duodenal and fundic motility were assessed. The compliance of the proximal stomach was determined by isobaric distensions. During fasting, exendin(9–39) did not influence proximal gastric volume, pyloric tone, and duodenal contractility. Exendin(9–39) significantly increased antral waves only in the absence of atropine. During duodenal meal perfusion, exendin(9–39) significantly reduced proximal gastric volume accommodation, abbreviated postprandial antral inhibition, reduced the postprandial increase in pyloric tone, and reduced gastric compliance. Atropine abolished the effects of exendin(9–39) on gastric volume accommodation but did not affect its effects on postprandial antroduodenal motility and on gastric compliance. Exendin(9–39) increased fasting and postprandial glycaemia and plasma glucagon but not insulin concentrations. Atropine did not affect GLP-1 secretion. Cholinergic mechanisms mediate the effects of GLP-1 on postprandial gastric accommodation but not on antro-pyloro-duodenal motility. GLP-1 reduces fasting and postprandial glycaemia, in part by reducing glucagon secretion.     

Mechanisms underlying duodeno-gastric reflux in man

BACKGROUND: Recent studies suggest that duodeno-gastro-oesophageal reflux (DGER) contributes to the occurrence of reflux oesophagitis and Barrett's oesophagus. The mechanisms underlying duodeno-gastric reflux (DGR), a prerequisite for DGER, are poorly understood. AIMS: To study the occurrence of DGR in relation to interdigestive and postprandial gastroduodenal motility. SUBJECTS AND METHODS: Ten healthy subjects underwent stationary gastroduodenal manometry with simultaneous duodenal and antral Bilitec recording 4 h before and 5 h after ingestion of a liquid meal. Eight volunteers underwent the same study, with administration of erythromycin postprandially. RESULTS: During the interdigestive phase II, all volunteers had short DGR episodes. Postprandially, DGR occurred in all subjects, on average 39 +/- 28 min after the start of the meal, and was cleared from the stomach after 242 +/- 23 min. Induction of increased antral motility and of a premature phase III, by administration of erythromycin, was associated with faster gastric DGR clearance. However, there was no direct temporal relationship between erythromycin-induced gastric phase III and erythromycin-induced DGR clearance. CONCLUSION: In healthy subjects, duodenogastric reflux occurs sporadically in the interdigestive state and is a normal phenomenon in the postprandial period. Erythromycin induces faster clearance of DGR from the stomach, which depends on enhanced antral contractile activity rather than premature phase III.     

Acute intraduodenal bile salt depletion leads to strong gallbladder contraction, altered antroduodenal motility and high plasma motilin levels in humans.

Cholecystokinin is the main hormone involved in postprandial gallbladder contraction. There is also considerable gallbladder contraction in the fasting state, associated with phase III of the gastrointestinal migrating motor complex and release of the hormone motilin. It has been proposed that intraduodenal bile salts exert a negative-feedback control on postprandial cholecystokinin release and resulting gallbladder contraction. We wanted to elucidate whether a similar control mechanism on gallbladder contraction exists in the fasting state. We therefore performed gallbladder ultrasonography and 24-h antroduodenal motility registrations and determined plasma cholecystokinin and motilin levels in six healthy subjects before and after acute (4 g) and chronic (8 days; 8 g day(-1)) oral cholestyramine. Acute cholestyramine strongly decreased gallbladder volumes and increased motilin without changed cholecystokinin levels. There was a negative relationship between gallbladder volumes and plasma motilin levels. Although there was a persistent fasting pattern of antroduodenal motility, its cycle length was increased (P < 0.03) with markedly longer phase II (P < 0. 005). Fasting gallbladder volumes 24 h later were still strongly decreased but gradually increased to pretreatment levels. Before and after 8 days cholestyramine, interdigestive and postprandial gallbladder emptying, intestinal migrating motor complex and hormone levels did not differ. We conclude that acute (but not chronic) intraduodenal bile salt depletion with cholestyramine affects gallbladder and antroduodenal motility, possibly partly related to motilin release.     

Studies of Small Intestinal Myoelectrical Activity and Intraluminal Pressure Changes in the Unrestrained Conscious Rat

Our aim was to develop and validate a methodology to permit chronic recordings of small intestinal intraluminal pressure changes in the conscious rat and thereby to study regional variations in motor activity. A low-flow (0.014 cc/min) perfusion system permitted reliable intraluminal pressure recordings at four sites along the small intestine from unrestrained animals. Comparison of overall patterns of fasted and fed motor activity and the various parameters of the migrating motor complex (MMC) from these recordings with those obtained from another group of animals prepared with serosal electrodes provided similar results in the proximal small intestine (MMC frequency 3.4 ± 0.5 vs. 3.9 ± 0.3 cycles/h, phase II duration 3.8 ± 0.7 vs. 4.7 ± 0.4 min, and phase III duration 4.0 ± 0.2 vs. 3.5 ± 0.2 min for duodenal catheters vs. electrodes, all NS). However, the distal deal phase II was considerably shorter in catheter than electrode recordings (6.0 ± 0.8 vs. 15.7 ± 2.4 min, p < 0.0001). Both methodologies confirmed significant regional variations in small intestinal motor parameters: the incidence of interdigestive myoelectrical complex (IDMEC) cycles was lower and phase II of the IDMEC was considerably prolonged in the distal Hewn. In summary, a system to permit chronic recordings of small intestinal intraluminal pressure has been developed and validated by comparison to myoelectrical recordings. Motor specialization was evident in the rat distal ileum.     

The Rectal Motor Complex

To identify patterns of motility in the rectum of humans during the day while awake and at night during sleep, and to correlate the patterns with interdigestive duodenal motor complexes and sleep cycles, intraluminal rectal pressure was recorded in 12 healthy subjects (five female, seven male; mean age, 28 years) using a flexible, noncompliant, silastic catheter and an Arndorfer system with a single perfused rectal port 6 cm above the anorectal junction, duodenal motility was recorded via a perfused oroduodenal tube, and sleep stages were determined electroencephalographically. Discrete bursts of rectal motor waves, called rectal motor complexes (RMCs), were identified on 72 occasions in 11 of the 12 subjects during 157 hours of recording. The RMCs were found in daytime during fasting or after feeding (0.2 ± 0.1 RMCs/hour), but were more easily and frequently identified at night during sleep (0.8 RMCs/hour, p < .01). The complexes had a distinct onset, a mean duration ± SEM of 9.5 ± 1.0 minutes, and a distinct decline. Within each complex, the waves had a mean frequency of 3.8 ± 0.3 per minute and a mean amplitude of 19 ± 2.7 mm Hg. Complex-to-complex intervals at night averaged 74 ± 15 minutes. No clear-cut temporal association was present between the complexes and phase III of interdigestive duodenal motor complex or the REM stage of sleep.     

Twenty-four hour ambulatory antroduodenal manometry in normal subjects (co-operative study)

Circadian antroduodenal motor activity was studied in 40 normal subjects by means of a portable recording system consisting of a computerized data logger and a probe with microtransducers. The quantitative and qualitative characteristics of contraction events during the interdigestive and digestive periods, as well as during the awake and asleep periods, were analysed. The composition and timing of meals and night recumbence were standardized. In spite of the high interindividual variability in motor parameters, significant differences in the characteristics of interdigestive and digestive periods between waking and sleep states were found. This paper confirms the existence of a circadian variation in antroduodenal motor activity and provides reference values from a large series of normal subjects that can be used for statistical comparisons with those obtained from patients recorded with the same method.     

49Sibutramine accelerates gastric emptying, inhibits intestinal motility in conscious dogs

Fasting interdigestive myoelectric complex (IMC) and postprandial gastroduodenal myoelectric activities are regulated by motilin and leptin, respectively (L. Zhou 2005). This study is to observe whether electrical acupuncture points could increase fasting gastroduodenal IMC and postprandial activities, as well as increase the release of motilin and leptin. Methods: Bipolar platinum electrodes were implanted on the serosa of antrum and duodenum in 10 conscious Wistar rats to record IMC and postprandial digestive myoelectric activities. We acupunctured Points Zusanli (S‐36), Tianshu (S‐25), and Liangmen (S‐21) during phase I of IMC (Frequency 20~100 Hz, Strengthen 12~16 mA, period 90 min) and compared with non‐specific electric stimulation (sham acupuncture) group. Serum motilin and leptin level was measured by RIA. Results: (1) Acupuncture points could shorten markedly phase I of antroduodenal IMC and increase the period of phase III (P < 0.01). Acupuncture points also increased the number of spike burst of antral and duodenal slow wave by (121.24 ± 20.0)% and (97.34 ± 15.20)% (compared with control group, P < 0.01). In postprandial period, acupuncture points could increase the number of spike burst of antral and duodenal slow wave by (142.52 ± 23.50)% and (102.48 ± 13.25)% (compared with control group, P < 0.01). (2) When acupuncture points increased the number of spike burst of IMC in fasting state, serum motilin concentration also increased, which was (74.56 ± 8.20)% more than control group (P < 0.01). When acupuncture points with meal, serum leptin concentration increased with myoelectric activity, which was (139.84 ± 20.25)% more than control group (P < 0.01). There was no change of motilin and leptin concentration in non‐specific electric stimulation group. (3) Cutting off subphrenic vagus nerves could totally block the effect of acupuncture points on antroduodenal myoelectric activities and release of motilin and leptin. Conclusions: Acupuncture points could effectively increase fasting and postprandial antroduodenal myoelectric activities. This effect is mediated by motilin and leptin, respectively.     

Myoelectrical Activity of the Stomach in Gastric Ulcer Patients: An Electrogastrographic Study

This study of gastric ulcer patients examined whether characteristic abnormalities in the fasting and postprandial gastric myoelectrical activity could be discerned electrogastrographically and whether these abnormalities, if present, were related to ulcer characteristics and complaints of nausea and vomiting. A total of 61 recordings were made in 31 gastric ulcer patients, both at the time of diagnosis and after ulcer healing, and these were compared to 52 recordings made in 52 control subjects. Several types of abnormal gastric myoelectrical activity were found in patients with an active ulcer: 1) instability of both the fasting and postprandial gastric frequency; 2) absence of the normal postprandial amplitude increase in the electrogastrogram; 3) waveform changes in the electrogastrographic signal in both the fasting and postprandial states; and 4) tachygastrias. These abnormalities were predominantly found in ulcer patients with symptoms of nausea and vomiting. They disappeared with ulcer healing and resolution of nausea and vomiting. These findings indicate that the abnormalities in gastric myoelectrical activity found in gastric ulcer patients are not merely due to the presence of the ulcer itself, but are associated with the presence of nausea and vomiting.     

Coordination of biliary and upper gastrointestinal motility in the fasted conscious pig

Abstract A chronic pig model was developed which permits the simultaneous measurement of integrated biliary motility as resistance to flow (CBD inflow), gallbladder, duodenal and gastric motility in addition to collection of venous blood samples for gut hormones estimations. Animals displayed a duodenal interdigestive cycle of 55.4 ± 3.4 min (mean ± SEM, n = 6), consisting of phase I, II and III (21.2 ± 2.1, 70.5 ± 2.0, 8.7 ± 0.5% of the cycle, respectively). A gastric inter-digestive cycle of 60.2 ± 6.5 min (n = 4) was similarly demonstrated consisting of three phases which corresponded to the three duodenal phases. The gastric phases I, II and III comprised 26.3 ± 3.0, 71.2 ± 2.7 and 2.5 ± 0.8% of the cycle, respectively. The gastric phase III immediately preceded the onset of the duodenal phase III. The gallbladder likewise displayed an interdigestive cycle of 54.5 ± 7.2 min (n = 6) consisting of a quiescent period (37.2 ± 3.7% of the cycle) corresponding temporally to duodenal phase III and phase I. This quiescent phase was followed by a period of rhythmic contractions (64.5 ± 4.1% of the cycle) which corresponded temporally to duodenal phase II. The onset of the gallbladder quiescent period coincided with the onset of duodenal phase III. The CBD inflow similarly demonstrated an interdigestive cycle of 53.4 ± 9.6 min (n = 4) duration, consisting of three phases. The initial phase was evident as a period of rapid inflow, the onset of which coincided with the onset of duodenal phase III and the gallbladder quies-centperiod, andoccupied 12.0 ± 0.8% of the cycle. The secondphase which occupied 18.0 ± 7.4% of the cycle, was typified as a period of declining inflow which reached a relatively stable level at a time corresponding to the end of duodenal phase I. The third phase consisted of the maintenance of the inflow rate achieved at the end of the previous phase (60% of maximum inflow), corresponding in onset and duration with duodenal phase II and occupied 70.0 ± 8.6% of the cycle. Plasma motilin levels fluctuated in relation to the duodenal interdigestive cycle, peaking during phase III relative to phase I (36.9 ± 8.5 vs 25.4 ± 7.7 pg mL^?1, respectively, n = 5, P < 0.05). Cholecystokinin levels did not fluctuate, remaining low (2.3 ± 2.1 pM cholecystokinin octapeptide equivalents, n = 5) throughout the duodenal interdigestive cycle, but increased about two fold after ingestion of solid food. Feeding disrupted the gastric, duodenal, gallbladder and CBD inflow cycles.     

Effects of duodenal flow on interdigestive patterns of small bowel myoelectric activity

Factors regulating the conversion of the interdigestive migrating motor complex (MMC) to postprandial patterns of motility are not completely understood. This study assessed the effects of varying rates of nonnutrient duodenal flow on patterns of interdigestive motility before and after abdominal vagotomy. Six neurally intact dogs were prepared with serosal intestinal electrodes and a duodenal infusion catheter. After recovery, the dogs were studied by infusing an isosmolar, noncaloric, balanced electrolyte solution at rates of 0, 3, 6, 9, or 12 ml/min for 5 hours into the proximal duodenum. With increasing rates of duodenal infusion, the duration of phase I decreased progressively (P < 0.05), while the period of the MMC remained unchanged. The MMC was eventually inhibited at rates of 9 or 12 ml/min with establishment of a pattern of intermittent spike activity. These findings were similar in 3 of these dogs after transthoracic total abdominal vagotomy. Our findings suggest that increases in duodenal infusion rate, independent of caloric or nutrient content, modulate patterns of intestinal motility during the postprandial period; this effect does not appear to be vagally mediated.     

Gastrointestinal Electrical Activity in the Prairie Dog During Fasting, Feeding, and After High-Cholesterol Diet

This study describes the electromyographic characteristics of the gastrointestinal tract of prairie dogs, and examines the effects of a 1.2% cholesterol diet on intestinal myoelectrical activity. Twelve prairie dogs were implanted with eight bipolar electrodes in the stomach and small bowel. Recordings were obtained during fasting (n = 12), gastric instillation of food (n = 7), and chronic cholesterol feeding for 3 weeks (n = 7). Gastric slow waves had a frequency per minute of 4.9 ± 1. Intestinal slow waves had a frequency per minute of 19.1 ± 2 in the duodenum, and of 16.8 ± 1 in the ileum. The migrating myoelectric complex (MMC) was identified, with an interval between two consecutive phases I of 145 ± 33 minutes. The delivery of diets of equal weight into the stomach interrupted fasting activity for approximately 3 hours. This was followed by a duodenal phase III and return of the fasted pattern. The interval between the first two postprandial phases I of the MMC not only was shorter than in the fasted state, but also was shorter after cholesterol diet than after regular diet (89 ± 33 min versus 116 ± 24 min, p ≤ 0.05). Chronic feeding of cholesterol diet did not affect the length of the MMC. In conclusion, the gastrointestinal tract of prairie dogs exhibits slow waves, spike bursts, and an MMC that is interrupted by feeding. High-cholesterol diet does not induce significant changes in the pattern of electrical activity.     

Gastric myoelectrical activity in premature and term infants

Electrogastrography is a non-invasive method for recording gastric myoelectrical activity. The aims of this study were to record gastric myoelectrical activity in newborn infants using electrogastrographic methods and to compare frequency distributions of postprandial electrogastrograms (EGGs) recorded after gavage feedings. Nineteen infants with gestational ages ranging from 28 weeks to term were studied. Group I subjects were studied only after formula feedings (n = 15) and were divided by age into subgroups A, B and C: A (term, n = 4), B (33–36 weeks, n = 4), and C (28–32 weeks, n = 7). Group II infants (32–34 weeks, n = 4) were studied before and after gavage feeding. The percentage of total EGG power was calculated for four frequency ranges: 1–2.4 cpm (bradygastria); 2.5–3.6 cpm (normal range); 3.7–9.9 cpm (tachygastria); and 10–15 cpm (duodenal/respiratory). Results showed no significant differences in postprandial EGG power in these frequency ranges among the Group I infants of different gestational ages. The power in these EGG frequency ranges did not change significantly after gavage feedings in the Group II infants. In conclusion: (a) EGGs may be recorded successfully from preterm and term infants, (b) postprandial gastric myoelectrical activity in all frequency bands is similar among groups of premature and term infants, and (c) gavage feedings in premature infants did not increase 3 cpm EGG activity.     

Gastric Myoelectric Activity in Patients with Chronic Idiopathic Gastroparesis

Gastric myoelectric and manometric activities were studied by means of a peroral probe in six patients with chronic idiopathic gastroparesis characterized by a marked delay in gastric emptying at scintigraphy and by interdigestive gastric hypokinesia at manometry. Six normal subjects were examined as controls. The study was carried out by means of a probe with Ag-AgCl suction-needle electrodes and an open-tip manometric catheter. In normal subjects this method was able to record in the distal gastric antrum a regular occurrence of pacesetter potentials at a frequency of about three per minute associated with bursts of spikes or secondary waves in correspondence with the pressure waves. In patients with chronic idiopathic gastroparesis a large variety of electric arrhythmias ranging from premature control potentials to tachygastria, tachyarrhythmia, bradygastria, and bradyarrhythmia and to a complete disorganization of electric control activity were recorded. As no pressure waves were recorded during these myoelectric disturbances, the antral motor impairment that characterizes chronic idiopathic gastroparesis may be considered pathogenetically related to the absence of a regular occurrence of gastric control potentials.     

Validation of antroduodenal motility measurements made by echo-planar magnetic resonance imaging

Echo planar imaging, a development of magnetic resonance imaging, can produce snapshot images of the stomach and antroduodenal segment in as little as 64 msec and can be more useful than conventional techniques when assessing motility. The aim of this study was to compare antroduodenal motility measured by simultaneous perfused tube manometry and echo planar imaging. Ten volunteers were studied following the ingestion of 500 mL water or 500 mL porridge. Antroduodenal images, with acquisition times of 130 msec, were taken at 3-sec intervals, synchronized with motility traces and presented as a split-screen video. This allowed direct visual comparison of gastric wall movement and motility to be made. Contractions were confined to either the stomach or the duodenum or propagated across the antroduodenal segment. Over 4550 images were available for analysis. A larger number of propagated contractions were recorded with echo planar imaging in both water (P = 0.03) and food (P = 0.02) groups, whereas manometry detected a greater number of isolated duodenal pressure waves (P = 0.005). The contraction rate for water and food studies was similar, but direct visualization indicated that the manometric technique under-detected propagated events. The ability of echo planar imaging to record antroduodenal contractile activity provides a new insight into the role of occlusive and nonocclusive contractions during gastric emptying.     

Oxyntomodulin and glicentin are potent inhibitors of the fed motility pattern in small intestine

Glicentin (GLIC) and oxyntomodulin (OXM or GLIC 33-69) are gut hormones which regulate digestion. They are known to reduce digestive secretions and to delay gastric emptying. Their biological activities on intestinal motility are still unknown. The effect of a systemic GLIC or OXM increase was investigated in rats on the food intake, the postprandial myoelectrical activity of small intestine and the orocaecal transit. An OXM or GLIC i.v. infusion was applied during the 5 min preceding food onset and during the first 15 min of food intake. This determined a three- to fourfold increase of the preprandial OXM-GLIC level. The OXM or GLIC plasma increase did not modify food intake. OXM infusion slowed down gastric emptying when the stomach contained 3/4 of the ingested food (before T 3 h). The quantity of food delivered in jejunum was subsequently smaller (P < 0.05). In the small intestine, the duration of postprandial myoelectrical activity (50-60 min g(-1) of ingested food) was reduced by 70% (P < 0.001) on duodenum or jejunum and by 54% (P < 0.01) on ileum in OXM-treated rats. An interdigestive motility profile was settled and an acceleration of both gastric emptying and transit rate was thereafter evidenced (after T 3 h). GLIC also reduced the duration of the postprandial myoelectrical activity on duodenum and jejunum (65 and 63% respectively, P < 0.05), but was not as efficient as OXM on ileum. In pathological states such as acute adult gastroenteritis, OXM and GLIC exhibit a two- to fivefold increase in their plasma concentrations. The present findings suggest that OXM and GLIC could, in that disease, contribute to exclude pathogens, due to their joined action on gut motility.     

Influence of naloxone on gastric emptying of solid meals, myoelectrical gastric activity and blood hormone levels in young healthy volunteers

There is considerable evidence that opioid mechanisms are involved in the mediation of pyloric motor responses that in turn regulate gastric emptying. The purpose of this randomized, placebo-controlled crossover study was to investigate the effect of naloxone on gastric emptying of a solid meal, gastric myoelectrical activity and the postprandial release of gastrointestinal peptides and neuropeptides in 20 healthy volunteers. Naloxone was administered as an intravenous bolus, followed by continuous infusion according to an intravenous dosing nomogram. Gastric emptying time was evaluated by scintigraphy and gastric myoelectrical activity was evaluated by cutaneous electrogastrography. Naloxone did not significantly alter gastric half-emptying time and postprandial dominant gastric electrical frequency compared with placebo. It also did not significantly change the plasma levels of several peptide hormones with the exception of neuropeptide Y, which was significantly increased (P = 0.001). In conclusion, in doses that influence human intestinal motility, naloxone had no effect on gastric motility and release of several peptide hormones in healthy male volunteers. The importance of the isolated increased neuropeptide Y plasma level needs further investigation.