Vagal system involvement in changes in small bowel motility during restraint stress: an experimental study in the dog

Enterocolic increase of cannabinoid receptor type 1 and type 2 and clinical improvement after probiotic administration in dogs with chronic signs of colonic dysmotility without mucosal inflammatory changes

BACKGROUND

Colonic dysmotility in dogs can cause different GI signs. Sometimes, histology of enterocolic biopsies does not reveal inflammatory infiltrates or mucosal lesions that are typically associated with clinical disease activity. It is speculated that, similarly to humans, colonic dysmotility may be anxiety-based, although recent data demonstrate that irritable bowel syndrome (IBS) could result from acute infectious enteritis. Specific Lactobacillus spp. strains administered orally in humans induced the expression of μ-opioid and cannabinoid receptors in mucosal enterocytes, modulating intestinal morphine-like analgesic functions. We investigated the potential association of GI signs caused by colonic dysmotility and mucosal expression of cannabinoid receptors in intestinal epithelial cells and the number of mucosal mast cells.

METHODS

Ten to 15 endoscopic biopsies were collected from colonic mucosa of 20 dogs diagnosed with dysmotility disturbances before and after probiotic (Slab51 bacterial blend; Sivoy^® ) administration (3-month period). Number and distribution of mast cells (MCs), and cannabinoid receptor type 1 (CB1) and type 2 (CB2) were evaluated by immunohistochemistry and PCR. Results were compared to data obtained from five clinically healthy dogs (archive samples).

KEY RESULTS

Decreased numbers of MCs (P < .0001) and increased CB1- and CB2-positive epithelial cells (P < .0001) in diseased dogs were positively associated with post-treatment CCECAI scores (P < .0001).

CONCLUSIONS AND INFERENCES

Our results suggest that probiotic administration can reduce signs of colonic dysmotility, possibly due to microbiota modulation and epithelial cell receptor-mediated signaling in intestinal mucosa.

Accelerometer-Based Assessment of Intestinal Peristalsis: Toward Miniaturized Low-Power Solutions for Intestinal Implants

Intestinal electrical stimulation via implants is already used to treat several disorders like constipation or incontinence. Stimulation parameters are most often empiric and not based on systematic studies. One prerequisite to evaluate effects of intestinal electrical stimulation is a direct assessment of intestinal motility. Some common methods are strain gauge transducers or manometry. With both the methods, it is not possible to record the exact 3-D movement. Therefore, we established a new method to record gastrointestinal motility with ultraminiaturized accelerometers, directly glued to the outer surface of the stomach, small intestine, and colon. With this technique, we were able to record precise local motility changes after electrical stimulation. Due to the low energy demand and the small size of the system, it is potentially useful for chronic measurements at multiple sites of the intestinal tract. We will present our first results regarding stimulation-dependent motility changes using up to eight implanted accelerometers in an acute pig model.

Melatonin Attenuates Noise Stress-induced Gastrointestinal Motility Disorder and Gastric Stress Ulcer: Role of Gastrointestinal Hormones and Oxidative Stress in Rats

BACKGROUND/AIMS

There are increasing evidences for gastrointestinal motility disorder (GIMD) and gastric stress ulcer induced by noise stress. The present study was to investigate the reversed effect of melatonin on GIMD and gastric stress ulcer induced by noise stress and potential mechanism.

METHODS

Noise stress was induced on rats, and melatonin (15 mg/kg) was administered to rats by intraperitoneal injection. Differences were assessed in gastric residual rate (GRR), small intestine propulsion rate (SPR), Guth injury score, cortisol, gastrointestinal hormones (calcitonin-gene-related peptide and motilin) and oxidative stress markers (superoxide dismutase and malondialde hyde) in blood plasma as well as gastric mucosa homogenate with or without melatonin. The pathological examination of gastric mucosa was also performed.

RESULTS

The GRR and SPR were improved by noise stress compared with control (P < 0.05). The pathological examination and Guth injury score revealed gastric stress ulcer. Moreover, the levels of cortisol, motilin and malondialdehyde in blood plasma and ma-londialdehyde in gastric mucosa homogenate were increased by noise stress (P < 0.05). CGRP and superoxide dismutase activ-ity in both of blood plasma and gastric mucosa homogenate were significantly decreased (P< 0.05). Furthermore, melatonin reversed changes in GRR, SPR, pathological examination, Guth injury score, cortisol, motilin, CGRP, superoxide dismutase activity and malondialdehyde (P < 0.05).

CONCLUSIONS

Melatonin is effective in reversing the GIMD and gastric stress ulcer induced by noise stress. The underlying mechanism may be involved in oxidative stress and gastrointestinal hormones.

Different mechanisms of intensification of contractile activity in the proximal and distal portions of the duodenum in psychogenic stress in rabbits

Psychogenic stress in rabbits induced by fixation of the animals to a frame was accompanied by an increase in contractile activity of the duodenum. Against the background of blockade of muscarinic and nicotinic cholinergic receptors and β(1)/β(2)-adrenoceptors this increase was observed in postpyloric portion, but not in the distal third of the duodenum. The increase in contractile activity was determined by the direct effect of the hormonal stress factor on smooth muscles in the first case and by the influence of circulating catecholamines on excitatory β-adrenoceptors of cholinergic neurons of the enteral nervous system in the second.

Effect of explosive noise on gastrointestinal transit and plasma levels of polypeptide hormones

AIM: To investigate the effect of firing noise on gastrointestinal transit and probe its mechanism by measuring the levels of plasma polypeptide hormones.

METHODS: A total of 64 SD rats were randomly divided into a control group and three stimulating groups. Firing noise of different intensity by sub-machine guns was used as inflicting factor. The effect of firing noise on liquid substance gastrointestinal transit and solid substance gastrointestinal transit was observed by measuring the ratio of carbon powder suspension transmitting and barium sticks transmitting respectively. Plasma levels of polypeptide hormones were measured by radio-immunoassay.

RESULTS: The noise accelerated gastrointestinal transit of solid food by more than 80 db;and accelerated gastrointestinal transit of liquid food significantly by more than 120 db. Meantime, plasma levels of plasma motilin (MTL)(157.47±16.08; 151.90±17.08), somatostatin (SS)(513.97±88.77; 458.25±104.30), substance P (SP)(115.52±20.70; 110.28±19.96) and vasoactive intestinal peptide (VIP) (214.21±63.17; 251.76±97.24) remarkably changed also.

CONCLUSION: Within a certain intensity range, the firing noise changes the levels of rat plasma gastrointestinal hormones, but the gastrointestinal transit is still normal. Beyond the range, the noise induces plasma hormone levels disturbance and gastrointestinal transit disorder.

Effects of psychological stress on small intestinal motility and bacteria and mucosa in mice

AIM: To investigate the effects of psychological stress on small intestinal motility and bacteria and mucosa in mice, and to explore the relationship between small intestinal dysfunction and small intestinal motility and bacteria and mucosa under psychological stress.

METHODS: Sixty mice were randomly divided into psychological stress group and control group. Each group were subdivided into small intestinal motility group (n = 10), bacteria group (n = 10), and D-xylose administered to stomach group (n = 10). An animal model with psychological stress was established housing the mice with a hungry cat in separate layers of a two-layer cage. A semi-solid colored marker (carbon-ink) was used for monitoring small intestinal transit. The proximal small intestine was harvested under sterile condition and processed for quantitation for aerobes (Escherichia coli) and anaerobes (Lactobacilli). The quantitation of bacteria was expressed as log₁₀(colony forming units/g). D-xylose levels in plasma were measured for estimating the damage of small intestinal mucosa.

RESULTS: Small intestinal transit was inhibited (39.80±9.50% vs 58.79±11.47%, P<0.01) in mice after psychological stress, compared with the controls. Psychological stress resulted in quantitative alterations in the aerobes (E. coli). There was an increase in the number of E. coli in the proximal small intestinal flora (1.78±0.30 log₁₀(CFU/g) vs 1.37±0.21 log₁₀(CFU/g), P<0.01), and there was decrease in relative proportion of Lactobacilli and E. coli of stressed mice (0.53±0.63 vs 1.14±1.07, P<0.05), while there was no significant difference in the anaerobes (Lactobacilli) between the two groups (2.31±0.70 log₁₀(CFU/g) vs 2.44±0.37 log₁₀(CFU/g), P>0.05). D-xylose concentrations in plasma in psychological stress mice were significantly higher than those in the control group (2.90±0.89 mmol/L vs 0.97±0.33 mmol/L, P<0.01).

CONCLUSION: Small intestinal dysfunction under psychological stress may be related to the small intestinal motility disorder and dysbacteriosis and the damage of mucosa probably caused by psychological stress.

Functional magnetic stimulation facilitates colonic transit in rats

OBJECTIVE

To investigate the effect of functional magnetic stimulation (FMS) on colonic transit in rats.

DESIGN

Experimental.

SETTING

Functional magnetic stimulation laboratory in a Veterans Administration health care system.

ANIMALS

Twenty-four female Wistar rats, divided into an experimental group and a control group.

INTERVENTIONS

All rats had technetium 99m (Tc 99m) infused through a cecal catheter to assess colonic transit times. FMS was performed over the cervical region; a figure of 8 magnetic coil was used in the experimental group. The colon was removed and sectioned into 10 segments, and a stool sample was taken in both groups.

MAIN OUTCOME MEASURES

Distribution of radioactivity within the large intestine and stool were measured.

RESULTS

Geometric center calculations showed significant differences (p <.001) between the control group and the experimental group when the distribution of radioactivity along the colon was measured. The percentage of Tc 99m recovered from the stool in the experimental group was significantly higher than the percentage recovered from the control group.

CONCLUSION

FMS facilitates colonic transit in a rat model.

Psychosocial aspects of Crohn's disease

In clinical practice, significant discrepancies occur between disease activity and severity, and the patient's symptom experience and behavior. Discrepancies cannot be explained by biologic or morphologic findings, and usually are considered to be related to psychosocial factors. Recent advances in the scientific understanding of the relationship between environmental stress and the neural, endocrine, and immune systems, combined with new methodologies in clinical research, provide a challenging opportunity for clinicians and researchers to establish a more comprehensive understanding of Crohn's disease. This article reviews the important relationship of psychosocial factors, pathogenesis, clinical expression, response to treatment, and outcome of Crohn's disease, and presents a comprehensive model of illness, disease, and ways to integrate psychosocial factors with diagnosis and patient care.

Abnormal cerebral processing of oesophageal stimuli in patients with noncardiac chest pain (NCCP)

In noncardiac chest pain (NCCP), altered visceral perception may result from abnormal cerebral processing of sensory input rather than abnormalities of afferent pathways. However, the interactions between symptoms, autonomic function and oesophageal stimuli are poorly studied. Oesophageal stimulation elicits reproducible cortical evoked potentials [CEP] and modulates heart rate variability via vagal pathways, as visible on power spectrum analysis of heart rate variability [PS-HRV]. These methods are increasingly used to study the function of visceral afferent neural pathways in human. The aim of this study was to compare EP and PS-HRV during oesophageal stimuli in NCCP and controls. Twelve healthy volunteers (one female, 11 male; aged 24-51 years; mean 32 +/- 8 years), and eight NCCP patients (three female, five male; age range 26-58, mean 40.5 +/- 10 years) were studied. Electrical oesophageal stimulation (EOS; 200 microseconds, 0.2 Hz, 25 stimuli) was applied to the oesophageal wall 5 cm above the lower oesophageal sphincter (LOS), and perception thresholds (measured in mA) determined. EP responses were recorded using 22 standard electroencephalogram scalp electrodes. Autonomic activity was assessed using PS-HRV, before, during, and after oesophageal stimulation. Measured PS-HRV indices included high frequency (HF; 0. 15-0.5 Hz) and low frequency (LF; 0.06-0.15 Hz) power, respectively, assessing vagal and sympathetic activity, and the LF/HF ratio. EOS perception occurred at lower thresholds in NCCP than in controls (3. 6 +/- 1 vs. 7.8 +/- 2 mA, P < 0.05). EP amplitude was greater (13 +/- 2 vs. 6 +/- 1 microV, P < 0.0001), and latency longer in controls vs. NCCP (191 +/- 7 ms vs. 219 +/- 6 ms, P < 0.001). In NCCP, EOS decreased sympathetic outflow (low frequency peak on PS-HRV) and increased cardiovagal activity (high frequency peak, P < 0.02) to a significantly higher degree in comparison with controls. During EOS, heart rate decreased in NCCP from 68 vs. 62 beats min-1 (P < 0.003) but not in controls. In NCCP patients, EOS was perceived at lower intensities and was associated with a greater cardiovagal reflex response. EP responses associated with EOS were smaller in NCCP than in controls, suggesting that an increased perception of oesophageal stimuli results from an enhanced cerebral processing of visceral sensory input in NCCP, rather than from hyperalgesic responses in visceral afferent pathways.

Effect of psychogenic stress on gastrointestinal function

This review summarizes the studies published over the last twenty years on the effects of psychogenic stress on gastrointestinal function, using animal models. The effects of stress on gastric ulceration have received wide attention and the central and local mechanisms of mucosal damage have been, for the most part, clearly delineated. In comparison, relatively few studies have focused on the impact of stress on intestinal and colonic physiology, even though its influence on intestinal motility, mucosal permeability and inflammation has been established. More work is necessary in this field, especially considering the importance of irritable bowel syndrome in modern society.

Functional magnetic stimulation facilitates gastrointestinal transit of liquids in rats

The purpose of this study was to investigate the effect of a relatively novel technology, functional magnetic stimulation (FMS), on gastrointestinal transit of liquids in rats. Orogastric gavage with technetium-99 solution was used to assess gastric emptying and gastrointestinal transit time in 92 rats. FMS was performed over the anterior cervical and/or dorsal thoracolumbar regions using a figure-8 coil. Stimulation protocols were 1, 2, or 4 h in length. FMS accelerated gastric emptying and decreased gastrointestinal transit time. The acceleration was dependent on the stimulation parameters used as well as on the duration of the protocol; high levels of FMS produced a quicker effect, whereas lower levels were effective at later times. This study provides evidence that FMS could be an alternative or adjunct therapy to treat disorders in gastrointestinal motility.