Inhibitory effects of stress on postprandial gastric myoelectrical activity and vagal tone in healthy subjects

Placebo effects on nausea and motion sickness are resistant to experimentally-induced stress

Nausea often occurs in stressful situations, such as chemotherapy or surgery. Clinically relevant placebo effects in nausea have been demonstrated, but it remains unclear whether stress has an impact on these effects. The aim of this experimental study was to investigate the interplay between acute stress and placebo effects in nausea. 80 healthy female volunteers susceptible to motion sickness were randomly assigned to either the Maastricht Acute Stress Test or a non-stress control condition, and to either placebo treatment or no treatment. Nausea was induced by a virtual vection drum and behavioral, psychophysiological as well as humoral parameters were repeatedly assessed. Manipulation checks confirmed increased cortisol levels and negative emotions in the stressed groups. In the non-stressed groups, the placebo intervention improved nausea, symptoms of motion sickness, and gastric myoelectrical activity (normo-to-tachy (NTT) ratio). In the stressed groups, the beneficial effects of the placebo intervention on nausea and motion sickness remained unchanged, whereas no improvement of the gastric NTT ratio was observed. Results suggest that placebo effects on symptoms of nausea and motion sickness are resistant to experimentally-induced stress. Stress most likely interfered with the validity of the gastric NTT ratio to measure nausea and thus the gastric placebo effect.

Integrative Effects and Vagal Mechanisms of Transcutaneous Electrical Acustimulation on Gastroesophageal Motility in Patients With Gastroesophageal Reflux Disease

INTRODUCTION

Impaired esophageal and gastric motilities are known to contribute to symptoms of gastroesophageal reflux disease (GERD). However, there is a lack of GERD therapy, targeting both gastric and esophageal functions. This study was designed to investigate the effects of transcutaneous electrical acustimulation (TEA) on symptoms of GERD and gastroesophageal functions and possible mechanisms in patients with GERD.

METHODS

Thirty patients with GERD with ineffective esophageal motility were equally divided and randomized into a 4-week sham-TEA or 4-week TEA treatment. The GERD questionnaire (GerdQ), GERD health-related quality-of-life questionnaire, high-resolution esophageal manometry, a nutrient drink test, the electrogastrogram, and ECG were performed to assess the severity of reflux symptoms, low esophageal sphincter (LES) pressure, distal contractile integral (DCI), gastric accommodation, gastric slow waves (GSW), and autonomic functions, respectively.

RESULTS

Compared with sham-TEA, the 4-week TEA treatment significantly decreased the GerdQ score (P = 0.011) and GERD health-related quality of life (P = 0.028) and improved nutrient drink-induced fullness (P < 0.001) and belching (P < 0.001) in patients with GERD. Although only acute TEA significantly enhanced LES pressure (P < 0.05), both acute and chronic TEA remarkedly increased DCI (P < 0.05) and reduced the incidence of ineffective esophageal contractions during wet swallows (P = 0.02). In addition, chronic TEA significantly increased gastric accommodation and the percentage of postprandial normal GSW compared with sham-TEA and baseline. Concurrently, TEA-enhanced vagal activity (P = 0.02) and the vagal activity positively correlated with LES pressure (r = 0.528; P = 0.003) and DCI (r = 0.522; P = 0.003).

DISCUSSION

The TEA treatment performed in this study improves reflux-related symptoms, increases DCI, reduces the incidence of ineffective esophageal contractions during wet swallows, and improves gastric accommodation and slow waves. The improvement in GERD symptoms might be attributed to the integrative effects of TEA on these gastroesophageal functions mediated via the vagal mechanism.

A Novel Approach in Spinal Cord Stimulation for Enhancing Gastric Motility: A Preliminary Study on Canines

Background/Aims

Gastroparesis is commonly seen in patients with diabetes and functional dyspepsia with no satisfactory therapies. Dysautonomia is one of the main reasons for the imbalanced motility. We hypothesized that spinal cord stimulation (SCS) is a viable therapy for gastroparesis via the autonomic modulation to improve gastric motility. The aim is to find an optimal method of SCS for treating gastroparesis.

Methods

Eight healthy-female dogs were implanted with a gastric cannula, a duodenal cannula, 2 multi-electrode spinal leads, and an implantable pulse generator. Gastric motility index (MI) was used to determine the best stimulation location/parameters of SCS. Optimized SCS was used to improve glucagon-induced gastroparesis.

Results

With fixed parameters, SCS at Thoracic 10 (T10) was found most effective for increasing gastric MI (37.8%, P = 0.013). SCS was optimized with different parameters (pulse width: 0.05–0.6 msec, frequency: 5–500 Hz, motor threshold: 30–90%) on T10. Our findings revealed that 0.5 msec, 20 Hz with 90% motor threshold at T10 were the best parameters in increasing MI. Glucagon significantly delayed gastric emptying, and this inhibitory effect was partially blocked by SCS. Gastric emptying at 120 minutes was 25.6% in the control session and 15.7% in glucagon session (P = 0.007 vs control), while it was 22.9% with SCS session (P = 0.041 vs glucagon). SCS with the optimal parameters was found to maximally enhance vagal activity and inhibit sympathetic activity assessed by the spectral analysis of heart rate variability.

Conclusions

SCS with optimized stimulation location and parameters improves gastric motility in healthy-dogs and accelerates gastric emptying impaired by glucagon via enhancing vagal activity.

Correlation between the motility of the proximal antrum and the high-frequency power of heart rate variability in freely moving rats

BACKGROUND

Cardiac vagal tone can be monitored non-invasively via electrocardiogram measurements of the high-frequency power spectrum of heart rate variability (HF-HRV). Vagal inputs to the upper GI tract are cumbersome to measure non-invasively. Although cardiac and GI vagal outputs arise from distinct brainstem nuclei, the nucleus ambiguus, and the dorsal motor nucleus of the vagus, respectively, we aim to test the hypotheses that in freely moving rats HF-HRV power is correlated to proximal antral motility and can be altered by high levels of circulating estrogen and vagal-selective treatments known to affect antral motility.

METHODS

Male and female Sprague-Dawley rats were implanted with a miniaturized strain gauge on the proximal gastric antrum and ECG electrodes to collect simultaneous antral motility and electrocardiogram. After recovery, male rats underwent baseline recordings before and after administration of saline (N = 8), cholecystokinin (CCK; N = 7), ghrelin (N = 6), or food (N = 6). Female rats (N = 6) underwent twice-daily recordings to determine baseline correlations during estrous cycle stages.

KEY RESULTS

There was a significant positive correlation between HF-HRV and proximal antral motility at baseline in males and females with low, but not high, estrogen levels. In male rats, the significant positive correlation was maintained following CCK, but not ghrelin or food administration.

CONCLUSIONS AND INFERENCES

Our data suggest that in rodents, HF-HRV positively correlates to proximal antral motility at baseline conditions in males and low-estrogen females or following interventions, such as CCK, known to affect vagal tone. This correlation is not observed when antral motility is influenced by more complex events.

Analysis of 19 Minerals and Cortisol in Red Deer Hair in Two Different Areas of the Stelvio National Park: A Preliminary Study

Simple Summary

Minerals play an important role in animals’ health and nutritional status and are associated with cortisol, a hormone involved in several physiological processes and with a fundamental role in allostasis, the process of achieving homeostasis. The aim of the present study is to perform a preliminary investigation on the concentration of 19 minerals and cortisol in the hair of red deer coming from two different areas of the Stelvio National Park. Results showed a close association between hair minerals and cortisol concentrations and an effect of deer origin. Hair minerals and cortisol assessment is an easy, rapid, and low cost screening method and it is useful in wildlife management programs, in order to investigate wild animals’ health status, to perform environmental studies, to assess the presence of contaminants in wild species and to determine risks for humans. In addition, it could be helpful in public health programs to estimate contamination risks linked to wild animal meat consumption or to assess the presence of contaminants in food-producing animals.

Abstract

The aim of the study was to perform an investigation on the concentration of 19 minerals and cortisol in red deer (Cervus elaphus) hair, a matrix that is easy to collect with non-invasive and painless sampling, able to represent an integrative values of long-term substance concentrations, and able to give useful information, also when performed on dead animals, given its extreme stability over time. In the study thirty-five animals were included, coming from two different sides of a valley in the Stelvio National Park, where official water analysis had pointed out elevated concentrations of As in one of the two orographic sides. Hair cortisol concentrations were measured using a RIA(Radio Immuno Assay), while minerals were detected using ICP-MS (Inductively Coupled Plasma- Mass Spectrometry). Results showed a negative relationship between cortisol and some mineral concentrations (Li, Co, As, Cd, Cr and Tl) and significant differences in some mineral concentrations between park areas (Al, Co, Cu, Cd and Ni). As, Cr and cortisol differences approached statistical significance. This preliminary study represents a step forward in the study of wildlife allostatic load and a valid method for applications in wildlife management programs, in environmental studies and in public health programs.

Temporary Gastric Stimulation in Patients With Gastroparesis Symptoms: Low-Resolution Mapping Multiple Versus Single Mucosal Lead Electrograms

Background

Cajal cells have a fundamental role in generating slow waves that regulate gastric motility. Gastric electrical stimulation (GES) is Food and Drug Administration (FDA)-approved for symptomatic treatment of drug refractory gastroparesis. We hypothesized that using two leads will vary from a single lead by providing greater insight of gastric electrical wave propagation, through differences in measured frequency, amplitude, and frequency over amplitude ratio. We also hypothesized that a significant reduction in symptomatic vomiting score is highly predictive in a single lead temporary gastric electrical stimulation.

Methods

A total of 111 patients with drug-refractory gastroparesis were enrolled. Forty-two patients had single lead, while 69 patients had two leads. All recordings measured mean frequency and amplitude in each lead. Patients documented symptoms using standardized symptom scores at baseline and day 5 post-procedure.

Results

Single lead patients with initial low mucosal frequency showed an increase from 3.10 to 4.93 (P = 0.0155), while the high frequency group decreased from 5.89 to 5.12 (P = 0.135). Vomiting score decreased significantly among both groups with GES (P = 0.0001). For two leads, the mucosal frequency decreased at the proximal electrode (P = 0.402), and increased at the distal electrode (P = 0.514), neither statistically significant (P = 0.143). Mucosal electrogram amplitude values changed for both proximal, mean decrease of 0.34 mV (P = 0.241), and distal, mean increase of 0.05 mV (P = 0.65) with a mean difference 0.34 mV (P = 0.238). However, mucosal electrogram frequency and amplitudes on day 5 were highly dependent on the baseline values (P < 0.001).

Conclusions

Compared to the use of single point electrodes, the use of two low-resolution electrodes allows recording gastric electrical wave propagation with greater detail. Low resolution recording appears to be superior to single point recordings, while awaiting practical high-resolution recordings.

The Interplay Between Nutrition and Stress in Pregnancy: Implications for Fetal Programming of Brain Development

Growing evidence supports an important role for the intrauterine environment in shaping fetal development and subsequent child health and disease risk. The fetal brain is particularly plastic, whereby even subtle changes in structure and function produced by in utero conditions can have long-term implications. Based on the consideration that conditions related to energy substrate and likelihood of survival to reproductive age are particularly salient drivers of fetal programming, maternal nutrition and stress represent the most commonly, but independently, studied factors in this context. However, the effects of maternal nutrition and stress are context dependent and may be moderated by one another. Studies examining the effects of the bidirectional nutrition-stress interplay in pregnancy on fetal programming of brain development are beginning to emerge in the literature. This review incorporates all currently available animal and human studies of this interplay and provides a synthesis and critical discussion of findings. Nine of the 10 studies included here assessed nutrition-stress interactions and offspring neurodevelopmental or brain development outcomes. Despite significant heterogeneity in study design and methodology, two broad patterns of results emerge to suggest that the effects of prenatal stress on various aspects of brain development may be mitigated by 1) higher fat diets or increased intake and/or status of specific dietary fats and 2) higher dietary intake or supplementation of targeted nutrients. The limitations of these studies are discussed, and recommendations are provided for future research to expand on this important area of fetal programming of brain development.

A pilot study on disturbed gastric myoelectric activity in obstructed defecation syndrome

BACKGROUND

Electrogastrography (EGG) is a noninvasive technique for recording gastric myoelectric activity. The aim of this study was to measure and record gastric myoelectric activity in patients with obstructed defecation syndrome (ODS) and to compare their results with those of normal individuals.

METHODS

Forty-two patients (22 male) with ODS and a mean age of 41.02 y were enrolled in this prospective study after thorough clinical and physiologic assessment. Eleven normal subjects (six female) with a mean age of 39.2 ± 8.4 y were assigned to the control group. Both patients and controls were subjected to surface EGG in fasting and postprandial states. Data were recorded and analyzed via a computer system to reveal the EGG pattern in both groups.

RESULTS

Abnormalities in the EGG were found in 24 (57.1%) of the 42 patients with ODS. EGG in ODS patients showed alterations in the fasting state in the form of a significant decrease of the normal gastric slow wave (P = 0.03) and a nonsignificant increase in gastric dysrhythmias. The EGG alterations of ODS patients were significantly improved in the postprandial state as the normal gastric slow waves significantly (P = 0.006) increased and the gastric bradycardia declined significantly (P = 0.02). No significant differences were observed in the power distribution between the ODS patients and the healthy controls.

CONCLUSIONS

Patients with ODS showed an altered EGG pattern compared with that of healthy control subjects. The alterations in ODS patients were more clearly observed during the fasting state and improved significantly after eating.

Gastric myoelectrical and neurohormonal changes associated with nausea during tilt-induced syncope

BACKGROUND

Nausea is a common prodromal symptom of neurally mediated syncope, but the biological factors linking nausea with syncope have not been studied. We aimed to characterize nausea during tilt-induced syncope by exploring related changes in gastric myoelectrical activity and plasma epinephrine, norepinephrine, and vasopressin concentrations across study phases of recumbency, tilt, syncope, and recovery.

METHODS

Electrogastrographic and plasma hormone changes were compared between patients with tilt-induced syncope and nausea (n = 18) and control subjects (n = 6) without symptoms or hemodynamic changes during tilt-table testing.

KEY RESULTS

Over a 4-minute period preceding syncope, sequential electrogastrography epochs demonstrated an increase over time in bradygastria (P = .003) and tachygastria (P = .014) power ratios, while the dominant frequency (P < .001) and the percent normogastria (P = .004) decreased. Syncope led to significant differences between cases and controls in electrogastrographic power ratios in each frequency range: bradygastria (P = .001), tachygastria (P = .005), and normogastria (P = .03). Nausea always followed electrogastrographic changes, and nausea resolution always preceded electrogastrographic normalization. Plasma vasopressin (676.5 ± 122.8 vs 91.2 ± 15.3 pg/mL, P = .012) and epinephrine (434 ± 91.3 vs 48.7 ± 2.5 pg/mL, P = .03), but not norepinephrine (P > .05), also differed with syncope between cases and controls.

CONCLUSIONS AND INFERENCES

The nausea related to tilt-induced syncope is temporally associated with changes in gastric myoelectrical activity and increases in plasma vasopressin and epinephrine. The biological mechanisms that induce syncope are physiologically distinct from other experimental models of nausea such as illusory self-motion, yet nausea with syncope appears to have similarly associated electrogastrographic and hormone changes. Thus, tilt-induced syncope could serve as an informative experimental model for nausea research.

Exposure to seawater increases intestinal motility in euryhaline rainbow trout (Oncorhynchus mykiss)

Upon exposure to seawater, euryhaline teleosts need to imbibe and desalinate seawater to allow for intestinal ion and water absorption, as this is essential for maintaining osmotic homeostasis. Despite the potential benefits of increased mixing and transport of imbibed water for increasing the efficiency of absorptive processes, the effect of water salinity on intestinal motility in teleosts remains unexplored. By qualitatively and quantitatively describing in vivo intestinal motility of euryhaline rainbow trout (Oncorhynchus mykiss), this study demonstrates that, in freshwater, the most common motility pattern consisted of clusters of rhythmic, posteriorly propagating contractions that lasted ∼1-2 min followed by a period of quiescence lasting ∼4-5 min. This pattern closely resembles mammalian migrating motor complexes (MMCs). Following a transition to seawater, imbibed seawater resulted in a significant distension of the intestine and the frequency of MMCs increased twofold to threefold with a concomitant reduction in the periods of quiescence. The increased frequency of MMCs was also accompanied by ripple-type contractions occurring every 12-60 s. These findings demonstrate that intestinal contractile activity of euryhaline teleosts is dramatically increased upon exposure to seawater, which is likely part of the overall response for maintaining osmotic homeostasis as increased drinking and mechanical perturbation of fluids is necessary to optimise intestinal ion and water absorption. Finally, the temporal response of intestinal motility in rainbow trout transitioning from freshwater to seawater coincides with previously documented physiological modifications associated with osmoregulation and may provide further insight into the underlying reasons shaping the migration patterns of salmonids.

The Interplay between Maternal Nutrition and Stress during Pregnancy: Issues and Considerations

BACKGROUND

Several studies about humans and animals have separately examined the effects of prenatal nutrition and stress on fetal development, pregnancy, and birth outcomes, and subsequent child health and disease risk. Although substantial evidence from non-pregnant literature supports the presence of bidirectional interactions between nutrition and stress at various psychological, behavioral, and physiological levels, such interaction effects have not yet been systematically examined in the context of pregnancy.

SUMMARY

This paper discusses the multifaceted and multilevel relationship between nutrition and stress. It then reviews the currently available observational and experimental evidence in animals and humans regarding the interplay between maternal psychosocial stress, dietary intake, and nutritional state during pregnancy, and implications for maternal and child health-related outcomes. Key Messages: During pregnancy, maternal psychosocial stress, dietary behavior, and nutritional state likely regulate and counter-regulate one another. Emerging evidence suggests that omega-3 fatty acids may attenuate maternal psychosocial stress, and that high maternal pre-pregnancy body mass index exacerbates unhealthy dietary behaviors under high-stress conditions. Longitudinal studies are warranted in order to understand the interplay between prenatal psychosocial stress, diet, and stress- and nutrition-related biomarkers to obtain further insight and inform the development and design of future, more effective intervention trials for improved maternal and child health outcomes.

The Effect of Acute Stress on Esophageal Motility and Gastroesophageal Reflux in Healthy Humans

Background/Aims

Little research has been done to evaluate the effect of stress in exacerbating the symptoms associated with gastroesophageal reflux (GER). We aimed to investigate the effect of acute stress on esophageal motility and GER parameters in healthy volunteers.

Methods

A total of 10 (M:F = 8:2, median age 34 years-old) healthy volunteers without any recurrent gastrointestinal symptoms participated in this study. They underwent esophageal high-resolution manometry with 10 wet swallows (Experiment I) and esophageal impedance-pH monitoring (Experiment II) in the basal period and in the stress period. In the stress period, either real stress or sham stress was given in a randomized cross-over design. The stress scores, symptom severity, and pulse rates were measured.

Results

The stress scores and the severity of nausea were significantly greater under real stress, compared with sham stress. The percentages of weak, failed, rapid, premature, and hyper-contractile contractions were not significantly altered during real stress and during sham stress, compared with the basal period. The median resting pressure of the lower esophageal sphincter and distal contractile integral of esophageal contractions did not differ in the stress period, compared with the basal period. Contractile front velocity and distal latency of esophageal peristaltic contractions were significantly changed during real stress, which was not observed during sham stress. GER parameters were not significantly altered during real stress and during sham stress.

Conclusion

Although acute auditory and visual stress seems to affect esophageal body motility, it does not induce significant motor abnormalities or increase GER in healthy humans.

Ameliorating effect of transcutaneous electroacupuncture on impaired gastric accommodation induced by cold meal in healthy subjects

BACKGROUND

Impaired gastric accommodation is recognized as one of major pathophysiologies in functional dyspepsia and gastroparesis. Electroacupuncture has been shown to improve gastric accommodation in laboratory settings. It is, however, unknown whether it exerts similar ameliorating effect in humans and whether needleless transcutaneous electroacupuncture (TEA) is also effective in improving gastric accommodation.

AIM

The aim was to investigate the effects of TEA on gastric accommodation, gastric slow waves, and dyspeptic related symptoms.

METHODS

Thirteen healthy volunteers were studied in four randomized sessions: control, cold nutrient liquid, cold nutrient liquid + sham-TEA, and cold nutrient liquid + TEA. The subjects were requested to drink Ensure until reaching maximum satiety. The electrogastrogram (EGG) and electrocardiogram (ECG) were recorded to assess the gastric and autonomic functions respectively.

RESULTS

1) Gastric accommodation was reduced with the cold drink in comparison with the warm drink (P = 0.023). TEA improved the impaired gastric accommodation from 539.2 ± 133.8 ml to 731.0 ± 185.7 ml (P = 0.005). 2) The percentage of normal gastric slow waves in six subjects was significantly decreased in the cold session (P = 0.002) and improved in the TEA session (P = 0.009 vs sham; P < 0.001 vs cold). 3) TEA showed significant improvement in the bloating (80.8 ± 5.7 vs 61.2 ± 26.2, P = 0.011), postprandial fullness (48.1 ± 12.0 vs 34.2 ± 21.2, P = 0.042), and nausea (29.6 ± 10.9 vs 19.2 ± 11.2, P = 0.026) in comparison with sham-TEA session. 4) Neither cold drink nor TEA altered vagal activities (P > 0.05).

CONCLUSIONS

TEA improves impaired gastric accommodation and slow waves induced by cold drink and the effect does not seem to be mediated via the vagal mechanisms.

Ameliorating effects and autonomic mechanisms of needle-less transcutaneous electrical stimulation at ST36 on stress-induced impairment in gastric slow waves

BACKGROUND AND AIM

Stress has long been documented to alter gastrointestinal motility. The effects of electroacupuncture (EA) on stress and gastric motility are relatively well known; however, whether EA has an ameliorating effect on stress-induced dysmotility remained unclear. This study aims to investigate the effects and mechanisms of needle-less transcutaneous electroacupuncture (TEA) on stress-induced impairment in gastric slow waves.

METHODS

A watch-size digital stimulator was developed. Ten healthy volunteers were involved in a four-session study (control, cold stress, TEA, and sham TEA). Electrogastrograpy was used to assess gastric slow waves, and electrocardiogram was recorded for the assessment of autonomic functions. The recordings were made in each session with/without stress and with TEA at ST36 or sham points.

RESULTS

The results are as follows: (i) Cold stress-induced gastric dysrhythmia and impaired normal slow waves (P < 0.01). TEA showed a preventive effect on cold stress-induced impairment in gastric slow waves. TEA at ST36, but not sham TEA, normalized slow waves (P = 0.03 vs stress; P = 0.44 vs control), attributed to the suppression of gastric dysrhythmia; (ii) Postprandially, there was a decrease in vagal activity in both control (P = 0.004) and stress (P = 0.002) sessions; this decrease was prevented with TEA (P < 0.05). Similarly, there was a postprandial increase in sympathetic activity in both control (P = 0.01) and stress (P = 0.002) sessions, and this increase was suppressed with TEA.

CONCLUSIONS

Needle-less TEA at ST36 using a watch-size stimulator is able to improve stress-induced impairment in gastric slow waves, possibly mediated via the autonomic mechanism. Home-based needle-less TEA may be a viable therapy for stress-induced impairment in gastric motility functions.

Effects of feeding on in vivo motility patterns in the proximal intestine of shorthorn sculpin (Myoxocephalus scorpius)

This is the first study to catalogue the diverse array of in vivo motility patterns in a teleost fish and how they are affected by feeding. Video recordings of exteriorised proximal intestine from fasted and fed shorthorn sculpin (Myoxocephalus scorpius) were used to generate spatio-temporal maps to portray and quantify motility patterns. Propagating and non-propagating contractions were observed to occur at different frequencies and durations. The most apparent difference between the feeding states was that bands of relatively high amplitude contractions propagating slowly in the anal direction were observed in all fasted fish (N=10) but in only 35% of fed fish (N=11). Additionally, fed fish displayed a reduced frequency (0.21±0.03 versus 0.32±0.06 contractions min(-1)) and rhythmicity of these contractions compared with fasted fish. Although the underlying mechanisms of these slow anally propagating contractions differ from those of mammalian migrating motor complexes, we believe that they may play a similar role in shorthorn sculpin during the interdigestive period, to potentially remove food remnants and prevent the establishment of pathogens. 'Ripples' were the most prevalent contraction type in shorthorn sculpin and may be important during mixing and absorption. The persistence of shallow ripples and pendular movements of longitudinal muscle after tetrodotoxin (1 μmol l(-1)) treatment suggests these contractions were myogenic in origin. The present study highlights both similarities and differences in motility patterns between shorthorn sculpin and other vertebrates, as well as providing a platform to examine other aspects of gastrointestinal functions in fish, including the impact of environmental changes.

Visceral hypersensitivity and electromechanical dysfunction as therapeutic targets in pediatric functional dyspepsia

Functional gastrointestinal disorders (FGID) are common clinical syndromes diagnosed in the absence of biochemical, structural, or metabolic abnormalities. They account for significant morbidity and health care expenditures and are identifiable across variable age, geography, and culture. Etiology of abdominal pain associated FGIDs, including functional dyspepsia (FD), remains incompletely understood, but growing evidence implicates the importance of visceral hypersensitivity and electromechanical dysfunction. This manuscript explores data supporting the role of visceral hypersensitivity and electromechanical dysfunction in FD, with focus on pediatric data when available, and provides a summary of potential therapeutic targets.

Postprandial cardiac vagal tone and transient lower esophageal sphincter relaxation (TLESR)

BACKGROUND

Transient lower esophageal sphincter relaxation (TLESR) is a vagally mediated reflex that occurs most frequently after a meal. Cardiac vagal tone (CVT) decreases after a meal, and correlates with changes in gastric electrical activity. Furthermore, decreased CVT has been reported in patients with gastro-esophageal reflux disease. We therefore aimed to characterize the association between postprandial changes in CVT and the occurrence of TLESR and reflux.

METHODS

Ten healthy volunteers underwent simultaneous autonomic nervous system, gastric myoelectric activity, lower esophageal-sphincter pressure, and reflux monitoring for 30 min in the fasting state, followed by a standard meal, and a further 4 h postprandially. Results are in mean ± SEM.

KEY RESULTS

The number of TLESRs (P < 0.0001) and reflux episodes (P < 0.0001) increased after the meal, while CVT decreased (P < 0.01). Cardiac sensitivity to baroreceptor reflex (CSB) showed similar time course changes to CVT (P = 0.06). During the first postprandial hour there was a strong correlation between the number of TLESRs and reflux episodes with CVT (R(2)  = 0.51 and R(2)  = 0.50, respectively; P < 0.05). There was also an increase in the dominant power and power ratio on electrogastrography (P < 0.05) after the meal.

CONCLUSIONS & INFERENCES

In healthy volunteers, the increase in the number of TLESRs and reflux episodes after a meal occurred mostly at a time of reduced CVT. Further studies should explore whether modulation of CVT can modify frequency of TLESRs and also this relationship should be further explored in patients with reflux disease.

Stress and food allergy: mechanistic considerations

Recent years have seen a marked increase in food allergy prevalence among children, particularly in Western countries, that cannot be explained by genetic factors alone. This has resulted in an increased effort to identify environmental risk factors underlying food allergies and to understand how these factors may be modified through interventions. Food allergy is an immune-mediated adverse reaction to food. Consequently, considerations of candidate risk factors have begun to focus on environmental influences that perturb the healthy development of the emerging immune system during critical periods of development (eg, prenatally and during early childhood), particularly in the gut. Given that psychosocial stress is known to play an important role in other allergic and inflammatory diseases, such as asthma, its potential role in food allergy is a growing area of research. However, research to date has largely focused on animal studies. This review synthesizes relevant animal research and epidemiological data, providing proof of concept for moderating influences of psychological stress on food allergy outcomes in humans. Pathways that may underlie associations between psychosocial stress and the expression of food allergy are discussed.

The effects of carbonated water upon gastric and cardiac activities and fullness in healthy young women

Although previous reports suggested that carbonated water drinking was effective against gastrointestinal symptoms, there is little information about the effects of carbonated water on gastric and appetite sensation. We therefore investigated the effect of carbonated water on short-term fullness with respect to gastric and cardiac responses in 19 healthy young women. Each subject was tested on three separate days at approximately 9 a.m. after an overnight fast. Gastric motility, evaluated by electrogastrography (EGG) and heart rate (HR), was measured for 20 min in the fasting state and 40 min after ingestion of water. Preloads consisted of an equivalent amount (250 mL) of water (W) or carbonated water (CW) and no drinking (blank). Fullness scores were measured using visual analog scales. To determine gastric motility, we assessed the component of bradygastria (1-2 cycles/min [cpm]), normogastria (2-4 cpm), tachygastria (4-9 cpm), and dominant frequency of the EGG power spectrum. After ingestion of CW, significant increases in fullness scores were observed compared with W. All postprandial EGG powers were significantly greater than preprandial, but no group difference was found. However, a dominant frequency tended to shift toward a lower band after ingestion of W. A significantly higher HR was found following consumption of CW as opposed to W. Multiple regression analysis revealed that increased HR was a significant variable contributing to the variances in fullness after ingestion of CW at 40 min. Our data suggest that CW may induce a short-term, but significant, satiating effect through enhanced postprandial gastric and cardiac activities due possibly to the increased sympathetic activity and/or withdrawal of parasympathetic activity.

Cross-sectional relationship between chronic stress and mineral concentrations in hair of elementary school girls

Chronic stress exposure is associated with diverse negative health outcomes. It has been hypothesised that stress may also negatively affect the body's mineral status. This study investigates the association between chronic stress and long-term mineral concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P) and zinc (Zn) in scalp hair among elementary school girls. Complete information on child-reported stress estimates (Coddington Life Events Scale (CLES)), hair cortisone and hair mineral concentrations, and predefined confounders in the stress-mineral relationship (i.e. age, body mass index, physical activity, diet, hair colour and parental education) was provided cross-sectionally for 140 girls (5-10 years old). The relationship between childhood stress measures (predictor) and hair minerals (outcome) was studied using linear regression analysis, adjusted for the abovementioned confounders. Hair cortisone concentrations were inversely associated with hair mineral concentrations of Ca, Mg, Zn and the Ca/P ratio. Children at risk by life events (CLES) presented an elevated Ca/Mg ratio. These findings were persistent after adjustment for confounders. This study demonstrated an independent association between chronic stress measures and hair mineral levels in young girls, indicating the importance of physiological stress-mineral pathways independently from individual or behavioural factors. Findings need to be confirmed in a more heterogeneous population and on longitudinal basis. The precise mechanisms by which stress alters hair mineral levels should be further elucidated.

Electrogastrography: methodology, validation and applications

Electrogastrography (EGG) is a non-invasive method for the measurement of gastric myoelectrical activity. It was first discovered in 1921 and popularized in 1990s. EGG is attractive because it is non-invasive. However, due to its non-invasive nature, there have also been controversies regarding validity and applications of EGG. The aim of this review is to discuss the methodologies, validation and applications of EGG. Pros and cons of EGG will also be discussed in detail. First, the gastric slow wave and its correlation with gastric motility are presented. The association between gastric dysrhythmia and impaired gastric motility is reviewed. Secondly the method for recording the electrogastrogram is presented in detail and pitfalls in the recording and analysis of EGG are discussed. Thirdly, findings reported in the literature demonstrating the accuracy of EGG in recording gastric slow waves and gastric dysrhythmia are reviewed and discussed. The correlation of the electrogastrogram with gastric contraction is carefully discussed. Finally, applications of EGG in a few major areas are reviewed.

Electrogastrography: methodology, validation and applications

Electrogastrography (EGG) is a non-invasive method for the measurement of gastric myoelectrical activity. It was first discovered in 1921 and popularized in 1990s. EGG is attractive because it is non-invasive. However, due to its non-invasive nature, there have also been controversies regarding validity and applications of EGG. The aim of this review is to discuss the methodologies, validation and applications of EGG. Pros and cons of EGG will also be discussed in detail. First, the gastric slow wave and its correlation with gastric motility are presented. The association between gastric dysrhythmia and impaired gastric motility is reviewed. Secondly the method for recording the electrogastrogram is presented in detail and pitfalls in the recording and analysis of EGG are discussed. Thirdly, findings reported in the literature demonstrating the accuracy of EGG in recording gastric slow waves and gastric dysrhythmia are reviewed and discussed. The correlation of the electrogastrogram with gastric contraction is carefully discussed. Finally, applications of EGG in a few major areas are reviewed.

Increased severity of dyspeptic symptoms related to mental stress is associated with sympathetic hyperactivity and enhanced endocrine response in patients with postprandial distress syndrome

BACKGROUND

Mental stress (MS) may alter gastric sensory-motor function. The aim of the study was to assess postprandial autonomic nervous system activity and stress hormones in response to acute mental stress in dyspeptic patients.

METHODS

A total of 25 patients with postprandial distress syndrome (PDS; 11 mol L(-1), age 35.9 ± 9.3 years) and 12 healthy controls (5 mol L(-1), age 25.8 ± 4.6 years) underwent electrogastrography and (13) C-octanoate gastric emptying study using a 480 kcal solid meal. Heart rate variability (LF/HF ratio) and corticotrophin-releasing factor, adrenocorticotropic hormone (ACTH), and cortisol serum levels were also evaluated. Dyspeptic symptoms were scored by analogue visual scale and expressed as symptoms total score (TS). The protocol was repeated twice in each subject, with and without a mental stress test before the meal.

KEY RESULTS

Mental stress significantly increased postprandial symptoms severity in patients (TS: stress 111 ± 18 vs basal 50 ± 10; P < 0.05). Low-/high-frequency component ratio was significantly higher in patients after MS at 120 min (stress 5.46 ± 0.41 vs basal 3.41 ± 0.64; P < 0.01) and 180 min (stress 5.29 ± 0.2 vs basal 3.58 ± 0.19; P < 0.05). During stress session, in patients we found a significantly higher ACTH level than baseline at 30, 60, 90, 150, 210, 240, and 270 min and a significantly higher cortisol level at 30, 60, 90, 120, 210, and 270 min. Gastric emptying rate and electrical activity were not influenced by MS.

CONCLUSIONS & INFERENCES

In PDS patients, administration of MS before meal increases symptoms severity by inducing sympathetic hyperactivity and increased stress hormones levels. As the gastric emptying looks not altered, we conclude that these neurohormonal responses mainly affect sensitive function.

Investigation of the effect of military stress on the prevalence of functional bowel disorders

AIM: To investigate the morbidity of functional bowel disorders (FBD) under military stress conditions in order to lay foundations for the prevention and treatment of this disease.

METHODS: Four hundred and fifty-seven soldiers who were assigned to specified services and 471 soldiers who were assigned to routine services were enrolled using cluster sampling, with the latter as a control group. They were surveyed using the Rome III FBD standard questionnaire. The FBD symptom questionnaire included FBD-related symptoms, severity, duration or attack time, and accompanying symptoms.

RESULTS: The morbidity of the military stress group (14.6%) was significantly higher than in the control group (9.98%) (χ² = 4.585, P < 0.05). The incidence of smoking, abdominal pain and acid regurgitation (χ² = 4.761, P < 0.05) as well as the ZUNG anxiety/depression scores (χ² = 7.982, P < 0.01) were also significantly higher in the military stress group compared with the control group. ZUNG anxiety (χ² = 11.523, P < 0.01) and depression (χ² = 5.149, P < 0.05) scores were higher in the FBD group compared with the non-FBD group. The differences in the ZUNG self-rated anxiety and depression scales between the 2 groups were statistically significant (χ² = 14.482, P < 0.01 and χ² = 6.176, P < 0.05).

CONCLUSION: The morbidity of FBD was higher under military stress conditions.

The role of psychoneuroimmunology in personalized and systems medicine

Psychoneuroimmunology (PNI) may provide the scientific basis for personalized and systems medicine. The exploration of the extensive interactions among psychological and behavioral factors, the nervous system, the immune system, and the endocrine system may help understand the mechanisms underlying health, wellness, and diseases. PNI theories based on systems biology methodologies may contribute to the identification of patient patterns for establishing psychological and physiological profiles for personalized medicine. A biopsychosocial model will help elucidate the systemic interrelationships between psychosocial and bio-physiological factors for the development of systems medicine. Many evidences have supported the close relationships between stress, depression, inflammation, and disorders including obesity, cardiovascular disease, diabetes, arthritis, skin diseases, infectious diseases, and sleep disorders. As inflammation is a critical connection among different diseases, the elucidation of the associations may contribute to the findings of systemic therapeutic targets. With the understanding of the translational implications of PNI, integrative interventions in multiple dimensions can be applied to modulate stress responses and promote healthier behaviors. These interventions include combination drug therapies, diets, nutritional supplements, meditation, and other behavioral and mind-body strategies.

The effect of a meal and water loading on heart rate variability in children with functional dyspepsia

BACKGROUND

Alteration in autonomic function has been implicated as a possible pathophysiologic mechanism in functional dyspepsia (FD) in adults.

METHODS

This was a two-part study. For the first part of the study, nine children with FD and 28 controls underwent heart rate variability (HRV) analysis for 30 min baseline and for 60 min following a test meal. For the second part of the study, eight children with FD and 26 controls underwent HRV analysis for 30 min baseline and for 60 min following rapid water loading. HRV analysis yielded measures for power in the high frequency (HF) band (vagal activity), power in the low frequency (LF) band (mainly sympathetic activity), and LF/HF (sympathovagal balance).

RESULTS

HRV parameters did not differ between FD patients and controls in either baseline period or following water loading. Following the meal, HF was higher and LF and LF/HF were lower in FD patients as compared to controls. Baseline LF/HF was positively correlated with the water load volume in controls and negatively correlated with the water load volume in FD patients.

CONCLUSION

FD in children is associated with an abnormal autonomic response best demonstrated following a meal. The relationship between baseline sympathovagal balance and water load volume in FD patients is distinctly different from the relationship in control children.

Stress, food, and inflammation: psychoneuroimmunology and nutrition at the cutting edge

Inflammation is the common link among the leading causes of death. Mechanistic studies have shown how various dietary components can modulate key pathways to inflammation, including sympathetic activity, oxidative stress, transcription factor nuclear factor-kappaB activation, and proinflammatory cytokine production. Behavioral studies have demonstrated that stressful events and depression can also influence inflammation through these same processes. If the joint contributions of diet and behavior to inflammation were simply additive, they would be important. However, several far more intriguing interactive possibilities are discussed: stress influences food choices; stress can enhance maladaptive metabolic responses to unhealthy meals; and diet can affect mood as well as proinflammatory responses to stressors. Furthermore, because the vagus nerve innervates tissues involved in the digestion, absorption, and metabolism of nutrients, vagal activation can directly and profoundly influence metabolic responses to food, as well as inflammation; in turn, both depression and stress have well-documented negative effects on vagal activation, contributing to the lively interplay between the brain and the gut. As one example, omega-3 fatty acid intake can boost mood and vagal tone, dampen nuclear factor-kappaB activation and responses to endotoxin, and modulate the magnitude of inflammatory responses to stressors. A better understanding of how stressors, negative emotions, and unhealthy meals work together to enhance inflammation will benefit behavioral and nutritional research, as well as the broader biomedical community.

Involvement of sympathetic function in the sleep-related change of gastric myoelectrical activity in rats

The gastric myoelectrical activity (GMA) fluctuates across sleep-wake states as a result of modulation by the brain-gut axis. The role of the autonomic nervous system in this phenomenon, however, was not elucidated fully. Through simultaneous recording and subsequent continuous power spectral analysis of electroencephalogram, electromyogram, electrocardiogram and electrogastromyogram (EGMG) in 16 freely moving Wistar rats, the sleep-wake states of the animals were defined and indices of cardiac autonomic regulation and GMA were calculated. We found that both cardiac autonomic regulation and GMA fluctuated through sleep-wake cycles. Correlation analysis further revealed significant correlations between EGMG power and each of the R-R interval, high-frequency power, low-frequency power, very-low-frequency power, low-frequency power to high-frequency power ratio and normalized low-frequency power of heart rate variability with respect to their trend of change across different sleep-wake states. These results suggest that the sleep-wake-related change of GMA was related to sympathovagal balance. The sympathetic nerve may play a more important role in the central modulation of GMA than perceived previously.

Postprandial changes in enteric electrical activity and gut blood flow in rainbow trout (Oncorhynchus mykiss) acclimated to different temperatures

Enteric electrical activity, cardiac output and gut blood flow were measured in rainbow trout (Oncorhynchus mykiss) acclimated to either 10 degrees C or 16 degrees C. Enteric electrical activity showed, in both the fasted and postprandial state, a distinct pattern with clusters of burst-like events interspersed by silent periods. The frequency of electrical events increased postprandially for both acclimation groups. Event frequency increased from 3.0+/-0.5 to 9.6+/-1.4 events min(-1) and from 5.9+/-0.9 to 11.8+/-2.0 events min(-1) in the 10 degrees C and 16 degrees C groups, respectively. Similarly, the number of events per cluster increased postprandially for both acclimation groups. Gut blood flow, cardiac output and heart rate increased after feeding. The gut blood flow significantly increased in both groups and peaked at 257+/-19% and 236+/-22% in the 10 degrees C and 16 degrees C groups, respectively. There was a strong correlation between the number of events and gut blood flow at both temperatures. Comparison between the two groups showed that fish acclimated to 16 degrees C may have an increased cost of sustaining the basal activity of the gut compared with the group acclimated to 10 degrees C. In conclusion, we have for the first time measured enteric electrical activity in vivo in a fish species and we have also demonstrated a strong correlation between gut blood flow and enteric electrical activity in fasted and postprandial fish.

Linear and non-linear measures indicate gastric dysmotility in patients suffering from acute schizophrenia

Cardiac autonomic dysfunction has been reported in patients suffering from schizophrenia. The aim of the present study was to evaluate gastric electrical activity in unmedicated patients suffering from acute schizophrenia in relation to their symptoms. Electrogastrography was performed before and after test meal ingestion in 26 patients suffering from schizophrenia and 26 matched controls. The non-linear measure approximate entropy (ApEn) was calculated for the first time from the obtained signal in addition to standardized measures. Results were correlated with the scales for the assessment of positive symptoms and negative symptoms. In addition, autonomic and abdominal symptoms were assessed by the autonomic symptom score. We found a significantly increased amount of tachygastria and arrhythmia within the signal of the activity of the gastric pacemaker before and after test meal digestion in patients compared to controls, indicating increased sympathetic modulation within the enteric nervous system. A significant difference was observed for slow wave, which represents the dominant frequency of gastric pacemaker activity, indicating gastric dysmotility in our patients. The elevated ApEn measure points to increased complexity and dysregulation. In addition, we have observed a correlation between delusions and tachygastria. Sympathetic function seems to be altered in the enteric nervous system of patients suffering from schizophrenia. Future studies need to explore the influence of the disease on different branches of the autonomic nervous system and clinical consequences of enteric dysfunction. Our findings point to a possible systemic autonomic imbalance that needs to be studied in respect to the neurobiology of schizophrenia.

Inhibitory effects of various types of stress on gastric tone and gastric myoelectrical activity in dogs

OBJECTIVE

Stress impairs gastrointestinal motility, causing, for example, delayed gastric emptying and altered intestinal transit. However, little is known about the effect of various stress factors on gastric tone and gastric myoelectrical activity (GMA). The aim of this study was to assess the effect of various kinds of stress on gastric tone and GMA in a canine model.

MATERIAL AND METHODS

Six dogs, implanted with a gastric cannula and one pair of gastric seromuscular electrodes, were studied. Three kinds of stress (visual, thermal, or audio stimulation) were applied in separate sessions. GMA and gastric tone were recorded for 30 min at baseline and 30 min during stress.

RESULTS

Visual stress (blinding) did not alter gastric tone or GMA; cold stress (ice water) and audio stress (loud noise) significantly inhibited gastric tone: gastric volume was increased from 107.2+/-13.5 ml at baseline to 135.6+/-23.8 ml with cold stress (p=0.041), and from 106.4+/-5.7 ml at baseline to 159.2+/-15.1 ml with audio stress (p=0.007). Although the dominant frequency or power of gastric slow waves was not altered, the percentage of normal gastric slow waves was markedly reduced from 98.3+/-0.8 to 87.5+/-3.7 with cold stress and from 90.2+/-3.3 to 80.6+/-2.9 with audio stress (p<0.05).

CONCLUSIONS

Cold- and audio stress inhibit gastric tone and impair gastric slow waves, whereas visual stress does not seem to have such effects. These findings will help to increase our understanding of gastrointestinal motor disorders related to stress.

Effect of thermal cutaneous stimulation on the gastric motor activity: Study of the mechanism of action

AIM: To investigate the mechanism of action of thermal cutaneous stimulation on the gastric motor inhibition.

METHODS: The gastric tone of 33 healthy volunteers (20 men, mean age 36.7 ± 8.4 years) was assessed by a barostat system consisting of a balloon-ended tube connected to a strain gauge and air-injection system. The tube was introduced into the stomach and the balloon was inflated with 300 mL of air. The skin temperature was elevated in increments of 3°C up to 49°C and the gastric tone was simultaneously assessed by recording the balloon volume variations expressed as the percentage change from the baseline volume. The test was repeated after separate anesthetization of the skin and stomach with lidocaine and after using normal saline instead of lidocaine.

RESULTS: Thermal cutaneous stimulation resulted in a significant decrease of gastric tone 61.2% ± 10.3% of the mean baseline volume. Mean latency was 25.6 ± 1.2 ms. After 20 min of individual anesthetization of the skin and stomach, thermal cutaneous stimulation produced no significant change in gastric tone.

CONCLUSION: Decrease in the gastric tone in response to thermal cutaneous stimulation suggests a reflex relationship which was absent on individual anesthetization of the 2 possible arms of the reflex arc: the skin and the stomach. We call this relationship the “cutaneo-gastric inhibitory reflex”. This reflex may have the potential to serve as an investigative tool in the diagnosis of gastric motor disorders, provided further studies are performed in this respect.

Intestinal electrical stimulation improves delayed gastric emptying and vomiting induced by duodenal distension in dogs

The aim of this study was to investigate the effects of short-pulse intestinal electrical stimulation (IES) on duodenal distention-induced delayed gastric emptying and vomiting in dogs and its possible mechanisms. The study was performed in 12 dogs with jejunal electrodes and a duodenal cannula in three separate experiments to investigate the effects of IES on duodenal distension (DD)-induced delayed gastric emptying and discomfort signs, vagal efferent activity, and jejunal tone. We found that: (i) IES significantly accelerated gastric emptying of liquid delayed by distension (18.05 +/- 4.06%vs. 7.18 +/- 1.99%, P = 0.036 at 60 min). (ii) IES significantly reduced vomiting and discomfort/pain induced by distension. The average signs score was 15.33 +/- 1.37 during distension which decreased to 6.50 +/- 0.91 (P = 0.0002) with IES. (iii) IES did not change vagal afferent activity, which was assessed by the spectral analysis of the heart rate variability. (iv) IES decreased jejunal tone. In conclusion, IES with parameters commonly used in gastric electrical stimulation for nausea and vomiting associated with gastroparesis improves DD-induced delayed gastric emptying and prevents DD-induced vomiting and discomfort signs. Further studies are warranted to investigate the therapeutic potential of IES for gastrointestinal symptoms associated with disturbances in motility and sensory function in small intestine.

Effects of audio stimulation on gastric myoelectrical activity and sympathovagal balance in healthy adolescents and adults

AIM

The primary aim of this study was to investigate the effects of different audio stimulations on gastric myoelectrical activity and sympathovagal balance in adolescents compared with adults.

METHODS

The study was performed in 11 adults and 12 adolescents. Each subject underwent two sessions, one for classical music, and the other for noise. Each session consisted of 30 min of baseline, 30 min of fasting audio stimulation, a test meal, 30 min of fed audio stimulation, and 30 min of recovery. Electrocardiogram and electrogastrogram were both recorded throughout each session.

RESULTS

(i) In the fasting state, both classical music and noise impaired gastric slow wave activity in adolescents. In adults, noise had no effects while classical music moderately improved slow wave rhythmicity. (ii) In the fed state, neither noise nor music had any effects on gastric slow waves. (iii) In the fasting state, both noise and music increased the sympathovagal balance in adolescents; in adults only noise had such an effect. (iv) The test meal increased the sympathovagal balance in all groups.

CONCLUSIONS

Gastric slow waves and the sympathovagal balance are more strongly affected by audio stimulation in adolescents than in adults. The test meal normalizes the audio stimulation-induced differences between the groups.

Effects of music on gastric myoelectrical activity in healthy humans

The aim was to study the effects of listening to music on gastric myoelectrical activity in healthy humans. Gastric myoelectrical activity was recorded using surface electrogastrography from 17 healthy volunteers before and for 30 min after they listened to music. All subjects listened to the same music. Ten perceived the music as enjoyable and seven did not. The percentages of normal slow wave, dominant frequency and dominant power did not differ significantly between baseline and during music intervention. An analysis of covariance model that included the subjects' feelings about the music and dominant power showed significantly higher dominant power during music intervention in subjects who enjoyed the music (p < 0.01). In the individuals who enjoyed the music, dominant power (55.0 +/- 9.2 dB) was significantly higher during music intervention than at baseline (49.5 +/- 6.8 dB, p = 0.03). In the subjects who did not enjoy the music, dominant power was significantly lower during music intervention than at baseline (48.8 +/- 6.8 and 55.7 +/- 6.2 dB, respectively; p < 0.01). Listening to enjoyable music increases the amplitude of gastric myoelectrical activity in healthy humans. Music therapy may improve gastric motility and may be used to stimulate gastric emptying.

Effects of chronic moderate alcohol consumption and novel environment on heart rate variability in primates (Macaca fascicularis)

RATIONALE

The effects of chronic moderate alcohol consumption on cardiac function are not understood. Acute stress may affect cardiac function by shifting autonomic cardiac regulation in favor of the sympathetic nervous system. Although alcohol consumption often increases at times of stress, the interactive effects of stress and chronic moderate alcohol consumption on cardiac regulation have not been studied.

OBJECTIVES AND METHODS

The objective was to assess the effects of long-term (1-2 years) moderate (a two-drink/day equivalent, 5 days/week) alcohol consumption on heart rate (HR) variability under normal and acutely stressful conditions in small stable groups of ovariectomized adult cynomolgus monkeys (Macaca fascicularis). Monkeys were trained to voluntarily drink their daily alcohol dose (<30 min), and blood levels were determined an hour later. The animals were acutely stressed by removal from the home cage to a novel environment for 30 min. HR in freely moving subjects was recorded via telemetry in the home cage and the novel environment.

RESULTS

Acute stress increased HR, decreased HR variability, and decreased the high frequency component of the power spectrum suggesting reduced parasympathetic cardiac modulation. Chronic moderate alcohol consumption decreased HR variability and the low frequency components of the power spectrum. When stressed, monkeys with a history of chronic moderate alcohol consumption had higher HRs than the controls.

CONCLUSIONS

HR dynamics in monkeys rapidly respond to acute stress. Chronic moderate alcohol consumption may be deleterious to cardiac function. HR response to stress may be exaggerated when accompanied by a history of chronic moderate alcohol consumption.

Autonomic nervous system response to a solid meal and water loading in healthy children: its relation to gastric myoelectrical activity

The aim of this study was to investigate the correlation of gastric myoelectrical and autonomic activities in healthy children. Simultaneous recordings of electrogastrography (EGG) and electrocardiogram (ECG) were performed in healthy children before and after a solid meal and water loading respectively. The autonomic activity was assessed by spectral analysis of the heart rate variability (HRV). The solid meal resulted in an increase in EGG-dominant frequency (2.92 cpm vs 3.16 cpm, P < 0.05), dominant power (46.9 dB vs 53.7 dB, P < 0.05) and percentage normal slow waves (81.9%vs 89.0%, P < 0.05), while only dominant power increased following water loading. Power in the low-frequency band of HRV (LF) was significantly increased and power in the high-frequency band of HRV (HF) significantly decreased following the solid meal. Postprandial LF was positively and HF negatively correlated with the postprandial increase in EGG-dominant power. Water loading was not associated with any significant changes in HRV parameters. These results suggest that both vagal and sympathetic pathways are involved in modulation of gastric myoelectrical activity.

Distension-induced gastric accommodation in functional dyspepsia: effect of autonomic manipulation

Functional dyspepsia (FD) is associated with impaired gastric accommodation and autonomic dysregulation. The aim of this study was to investigate the effects of autonomic manipulation on distension-induced gastric accommodation in subjects with and without FD, using a newly developed gastric barostat paradigm. Twelve healthy subjects (HS) and 18 subjects with FD had four barostat examinations each: no intervention, intravenous atropine (1 mg), vagal stimulation (mental relaxation with deep breathing) and acute stress stimulation (serial subtraction task). Intrabag pressure increased from 1 to 15 mmHg in 5 min (ramp phase), and was maintained at 15 mmHg for 5 min (tonic phase). Volume responses were analysed using predefined parameters. There were no significant group differences in accommodation variables between HS and subjects with FD. The FD group could be subdivided into two distinct subgroups: subgroup 1 (n = 7, 38%) with low maximum volume and accommodation rate, and subgroup 2 with normal accommodation (n = 11). In subgroup 1, but not in subgroup 2 atropine increased maximum volume and accommodation rate substantially. Neither mental stress nor mental relaxation changed any of the accommodation variables. In a subgroup of subjects with FD, impairment of distension-induced gastric accommodation can be improved by cholinergic blockade, but not by acute physiological autonomic manipulation.

Measurement of human gastric motility by near-infrared light for the assessment of chronic mental stress

In this study, we focused on the relationship between mental stress and gastric motility and have tried to develop a measurement system of human gastric motility for the quantification of mental stress. A mental stress measurement system should be used easily in daily life. However, general measurement system as electrogastrography, endoscopy, CT, ultrasonic echogram isn't suitable for the home use. Then, we have developed non-invasive and compact measurement system of gastric motility using near-infrared (NIR) light. This system consists of NIR LEDs and an avalanche photodiode (APD). APD receives the NIR light transmitting outside the body from NIR LEDs and reflecting on the gastric wall. In the experiment, an ultrasonic echogram was used simultaneously to confirm our new method. The result showed that the waveform got by our method coincides with the cycle of contractile activity of stomach, and it was proved that our measurement system using NIR light could measure gastric motility. In addition, we performed chronic mental stress measurement intended for students to examine relationship between chronic mental stress and gastric motility. Experimental period was from two weeks before graduation examination to two weeks after graduation examination. The result showed that chronic mental stress may invoke gastric dysrhythmia, and chronic mental stress could be evaluated by long term monitoring of gastric motility using our NIR measurement system.

Alteration of gastric myoelectrical and autonomic activities with audio stimulation in healthy humans

OBJECTIVE

Cold or emotional stress was reported to affect gastric myoelectrical activity. The aim of this study was to investigate the effects of music or noise on gastric myoelectrical activity and autonomic function in healthy volunteers.

MATERIALS AND METHODS

The study was performed in 10 fasted healthy volunteers and included 30 min at baseline, 30 min of classical music via headphones and 30 min of loud household noises via headphones. The electrogastrogram (EGG) readings were recorded simultaneously with the electrocardiogram (ECG) recording.

RESULTS

Both classical music and noise altered the regularity of gastric slow waves. The percentage of normal 2-4 cycles/min (cpm) waves was reduced from 77.9 +/- 4.7% at baseline to 66.9 +/- 5.4% during music (p < 0.006) and 67.7 +/-5.4% during noise (p < 0.05). The reduction was attributed to a significant increase in bradygastria (15.8 +/- 3.9% versus 9.8 +/- 2.6%, p < 0.04) with the music and a significant increase in arrhythmia (7.4 +/- 1.6% versus 2.0 +/- 1.1%, p < 0.02) with the noise. The dominant frequency and power of the EGG were, however, not altered with either music or noise. Neither music nor noise had any effect on the autonomic function assessed by the heart rate variability.

CONCLUSIONS

Audio stimulation, with both music and noise, alters the rhythmicity of gastric slow waves. Classical music seems to increase bradygastria, whereas, household noise may increase arrhythmia. The effect of audio stimulation on the gastric slow wave does not seem to involve sympathetic or vagal efferent pathways assessed by the spectral analysis of heart rate variability.