Pressure responses to OP-CCK compared to CCK-PZ in the antrum and fundus of isolated guinea-pig stomachs

Importance of the enteric nervous system in the control of the migrating motility complex

The migrating motility complex (MMC), a cyclical phenomenon, represents rudimentary motility pattern in the gastrointestinal tract. The MMC is observed mostly in the stomach and gut of man and numerous animal species. It contains three or four phases, while its phase III is the most characteristic. The mechanisms controlling the pattern are unclear in part, although the neural control of the MMC seems crucial. The main goal of this article was to discuss the importance of intrinsic innervation of the gastrointestinal tract in MMC initiation, migration, and cessation to emphasize that various MMC-controlling mechanisms act through the enteric nervous system. Two main neural regions, central and peripheral, are able to initiate the MMC. However, central regulation of the MMC may require cooperation with the enteric nervous system. When central mechanisms are not active, the MMC can be initiated peripherally in any region of the small bowel. The enteric nervous system affects the MMC in response to the luminal stimuli which can contribute to the initiation and cessation of the cycle, and it may evoke irregular phasic contractions within the pattern. The hormonal regulators released from the endocrine cells may exert a modulatory effect upon the MMC mostly through the enteric nervous system. Their central action could also be considered. It can be concluded that the enteric nervous system is involved in the great majority of the MMC-controlling mechanisms.

Control of Food Intake by Gastrointestinal Peptides: Mechanisms of Action and Possible Modulation in the Treatment of Obesity

This review focuses on the control of appetite by food intake-regulatory peptides secreted from the gastrointestinal tract, namely cholecystokinin, glucagon-like peptide 1, peptide YY, ghrelin, and the recently discovered nesfatin-1 via the gut-brain axis. Additionally, we describe the impact of external factors such as intake of different nutrients or stress on the secretion of gastrointestinal peptides. Finally, we highlight possible conservative—physical activity and pharmacotherapy—treatment strategies for obesity as well as surgical techniques such as deep brain stimulation and bariatric surgery also altering these peptidergic pathways.

Effects of Seal Oil on Meal-Induced Symptoms and Gastric Accommodation in Patients with Subjective Food Hypersensitivity: A Pilot Study

Background

Food hypersensitivity is a prevalent condition with poorly characterized underlying mechanisms. In the present pilot study we investigated effects of seal oil and soy oil on meal-induced symptoms and gastric accommodation in patients with subjective food hypersensitivity (FH). Single dose experiment: On three consecutive days, 10 mL of seal oil, soy oil, or saline were randomly administered into the duodenum of 10 patients with subjective FH and 10 healthy volunteers through a nasoduodenal feeding tube 10-20 minutes before the ingestion of a test meal. Short-term treatment study: 24 patients with subjective FH were randomly allocated to 10 days’ treatment with either 10 mL of seal or soy oil, self-administrated through an indwelling nasoduodenal feeding tube, 3 times daily. In both experiments meal-induced abdominal symptoms and gastric accommodation were measured by visual analogue scales and external ultrasound respectively.

Results

Symptoms and gastric accommodation were not significantly influenced by single doses of seal or soy oil. When given daily for 10 days, seal oil, but not soy oil, reduced total symptom scores significantly ( P = 0.03). The symptomatic improvement was not associated with improvements in gastric accommodation.

Conclusion

Daily administration of seal oil may benefit patients with subjective FH. The beneficial effect of seal oil in patients with subjective FH can not be ascribed to improved gastric accommodation.

Levels of vasoactive intestinal peptide, cholecystokinin and calcitonin gene-related peptide in plasma and jejunum of rats following traumatic brain injury and underlying significance in gastrointestinal dysfunction

AIM: To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.

METHODS: Rat models of focal traumatic brain injury were established by impact insult method, and divided into 6 groups (6 rats each group) including control group with sham operation and TBI groups at postinjury 3, 12, 24, 72 h, and d 7. Blood and proximal jejunum samples were taken at time point of each group and gross observations of gastrointestinal pathology were recorded simultaneously. The levels of vasoactive intestinal peptide (VIP) in plasma, calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in both plasma and jejunum were measured by enzyme immunoassay (EIA). Radioimmunoassay (RIA) was used to determine the levels of VIP in jejunum.

RESULTS: Gastric distension, delayed gastric emptying and intestinal dilatation with a large amount of yellowish effusion and thin edematous wall were found in TBI rats through 12 h and 72 h, which peaked at postinjury 72 h. As compared with that of control group (247.8 ± 29.5 ng/L), plasma VIP levels were significantly decreased at postinjury 3, 12 and 24 h (106.7 ± 34.1 ng/L, 148.7 ± 22.8 ng/L, 132.8 ± 21.6 ng/L, respectively), but significantly increased at 72 h (405.0 ± 29.8 ng/L) and markedly declined on d 7 (130.7 ± 19.3 ng/L). However, Plasma levels CCK and CGRP were significantly increased through 3 h and 7 d following TBI (126-691% increases), with the peak at 72 h. Compared with control (VIP, 13.6 ± 1.4 ng /g; CGRP, 70.6 ± 17.7 ng/g); VIP and CGRP levels in jejunum were significantly increased at 3 h after TBI (VIP, 35.4 ± 5.0 ng/g; CGRP, 103.8 ± 22.1 ng/g), and declined gradually at 12 h and 24 h (VIP, 16.5 ± 1.8 ng/g, 5.5 ± 1.4 ng/g; CGRP, 34.9 ± 9.7 ng/g, 18.5 ± 7.7 ng/g), but were significantly increased again at 72 h (VIP, 48.7 ± 9.5 ng/g; CGRP, 142.1 ± 24.3 ng/g), then declined in various degrees on d 7 (VIP, 3.8 ± 1.1 ng/g; CGRP, 102.5 ± 18.1 ng/g). The CCK levels in jejunum were found to change in a similar trend as that in plasma with the concentrations of CCK significantly increased following TBI (99-517% increases) and peaked at 72 h.

CONCLUSION: Traumatic brain injury can lead to significant changes of brain-gut peptides in both plasma and small intestine, which may be involved in the pathogenesis of complicated gastrointestinal dysfunction.

Effect of cholecystokinin and secretin on contractile activity of isolated gastric muscle strips in guinea pigs

AIM: To study the effect of cholecystokinin-octapeptide (CCK- 8) and secretin on contractile activity of isolated gastric muscle strips in guinea pigs.

METHODS: Each isolated gastric muscle strip was suspended in a t issue chamber containing 5 mL Krebs solution constantly warmed by water jacked at 37 °C and supplied with a mixed gas of 95% O₂ and 5% CO₂. After incubating for 1h under 1g tension, varied concentrations of CCK-8 and se cretin were added respectively in the tissue chamber and the contractile response was measured isometrically on ink-writing recorders.

RESULTS: CCK-8 could increase ① all regional circular and longitudinal muscular tension at rest (fundus LM 19.7% ± 2.1%, P < 0.01; fundus CM 16.7% ± 2.2%, P < 0.01; gastric body LM 16 .8% ± 2.3%, P < 0.01; body CM 12.7% ± 2.6%, P < 0.01; antrum LM 12.3% ± 1.3%, P < 0.01; antrum CM 16.7% ± 4.5%, P < 0.01; pylous CM 12.7% ± 5.0%, P < 0.05); ② contractile frequencies of body LM, both LM and CM of antrum and pylorus CM (5.1/min ± 0.2/min to 5.6/min ± 0.2/min, 5.9/min ± 0.2/min to 6.6/min ± 0.1/min, 5.4/min ± 0.3/min to 6.3/min ± 0.4/min, 1.3/min ± 0.2/min to 2.3/min ± 0.3/min, respectively, P < 0.05); ③ the mean contractile amplitude of antral circular mus cle (58.6% ± 18.4%, P < 0.05) and ④ the motility index of pylorus CM (145.0% ± 23.8%, P < 0.01), but decrease the mean contractile ampl itude of gastric body and antral LM (-10.3% ± 3.3%, -10.5% ± 4.6%, respectively, P < 0.05). All the CCK-8 effects were not blocked by atropine or ind omethacin. Secretin had no effect on gastric smooth muscle activity.

CONCLUSION: CCK-8 possessed both excitatory and inhibitory action on contractile activity of different regions of stomach in guinea pigs.Its action was not mediated via cholinergic M receptor and endogenous prostaglandin receptor.

Misoprostol is effective treatment for patients with severe chronic constipation

To assess the efficacy of misoprostol in the treatment of patients with severe chronic constipation, nine such patients were enrolled in a double-blind, randomized, crossover study of misoprostol (1200 micrograms/day) or placebo, that lasted three weeks. During this period each patient received the drug for one week and placebo for another with a week washout period in between. A colonic transit study, using radiopaque markers, was performed during each of the treatment weeks, while the number of stools and their total weight was recorded by each patient for the appropriate periods. Colonic transit time was significantly and consistently decreased by misoprostol compared to placebo [66 hr +/- 10.2 vs 109.4 hr +/- 8.1 (P = 0.0005)]. Misoprostol significantly increased the total stool weight per week [976.5 g +/- 288.8 vs 434.6 g +/- 190.5 (P = 0.001)] and also significantly increased the number of stools per week compared to placebo [6.5 +/- 1.3 vs 2.5 +/- 0.11 (P = 0.01)]. The incidence of abdominal pain was similar in both groups. We concluded that misoprostol, during a short trial period, proved effective in increasing the frequency and weight of bowel movements and decreasing colonic transit time in patients with severe chronic constipation. It may be used as a therapeutic measure to treat such patients.

Contractile responses of canine gastric muscle to peptides of the cholecystokinin group

1 Mechanical activity was recorded in isolated muscle preparations from the circular and longitudinal layers of different regions of canine stomach (16 dogs). At least eight muscle strips were excised from each stomach: longitudinal (lo) and circular (ci) strips from fundus (Fu), corpus (Co) and antrum (An), and circular strips from the inner and outer portion of the pyloric ring. 2 Cholecystokinin 33 (CCK 33), cholecystokinin octapeptide (CCK 8), caerulein and pentagastrin produced the same pattern of responses, with differences in their potencies: caerulein was 10 times more potent than CCK 8, and CCK eight to ten times more potent than CCK 33 and pentagastrin. 3 The most characteristic effect of the CCK peptides was an increase in frequency of the phasic activity of Fu-ci, Co and An preparations (threshold 10(-10) mol/l for CCK 8), usually combined with weak or moderate increases of amplitude. 4 Slight tonic activations were observed in Fu-lo, Co-lo and An-lo (around 10% of the ACH maximum), and stronger tonic activations in Fu-ci and Co-ci (around 50% of the ACH maximum). 5 No responses to CCK were seen in pyrolic preparations. 6 Experiments with receptor antagonists (adrenoceptors, muscarinic and histamine receptors), and with tetrodotoxin indicate that the peptides act by a direct effect on smooth muscle.

Prostaglandin E2 in jejunal fluids and its potential diagnostic value for selecting patients with indomethacin-sensitive diarrhoea

Since prostaglandins (PGs) appear to be important in the pathogenesis of secretory diarrhoea, a radioimmunoassay for determination of PGE2 was applied to purified samples of jejunal fluids aspirated at the ligament of Treitz. Studies on validation of the assay system included quantification of PGE2 following alkali-treatment of the samples, variation of the sample volume, and fractionation of immunoreactive- and tracer PGE2. In addition, the specificity of the assay system was confirmed by gas chromatography--mass spectrometry. In healthy volunteers (n = 22) the PGE2 concentration range was 5--205 pg/ml (99% confidence limits). Alcohol addicts (n = 27) with diarrhoea or steatorrhoea had PGE2 levels within the normal range. Values beyond the 99% upper confidence limit were observed in ten out of seventeen patients with chronic diarrhoea (205--340 pg/ml) and two out of fifteen patients with intermittent diarrhoea (265 and 275 pg/ml) classified as irritable bowel syndrome. In six patients with high PGE2 concentrations indomethacin treatment (25 mg x 4 daily) halved the associated diarrhoea and reduced PGE2 concentrations to normal levels. Subsequently, a double-blind multiple randomized clinical trial was carried out in two single patients. Indomethacin proved to be effective in preventing diarrhoea only in the patient with a raised PGE2 level (P less than 0.005).