Intestinal chemo- and mechano-sensitivity: selective modification of small intestinal sensitivity by lipids

Case Report of Presumed (In)voluntary Capsaicin Intoxication Mimicking an Acute Abdomen

Background

The clinical features of a presumed capsaicin intoxication have not been reported so far. Case Presentation. A 27-year-old man took part in a qualifying for a competition in spicy food tolerance. During this qualifying, he swallowed 4 chili peppers type Bhut jolokia (about 1 million Scoville units) and other extremely spicy foods; the total amount of capsaicin ingested (roughly calculated retrospectively) accounted for at least 600 mg. After 2½ hours, the patient developed severe abdominal pain, which led to hospital admission. In contrast to the severe symptoms, clinical, laboratory, and imaging examinations (ultrasound and plain X-ray of the abdomen) did not reveal any significant abnormalities. Treatment with analgesics resulted in complete regression of the abdominal pain within 30 hours.

Conclusions

The clinical picture in the view of pharmacological investigations on intestinal capsaicin infusions suggests that excessive doses of capsaicin can induce severe abdominal pain; the prolonged symptoms were probably due to the failure to vomit. Thus, a capsaicin intoxication must be considered in the differential diagnosis of an acute abdomen.

Chain length of dietary fatty acids determines gastrointestinal motility and visceromotor function in mice in a fatty acid binding protein 4-dependent manner

Purpose

We hypothesize that different types of dietary fatty acids (FAs) affect gastrointestinal (GI) motility and visceromotor function and that this effect can be regulated by the fatty acid binding protein 4 (FABP4).

Methods

Mice were fed for 60 days with standard diet (STD), STD with 7% (by weight) coconut oil, rich in medium-chain FAs (MCFAs) (COCO), or with 7% evening primrose oil, rich in long-chain FAs (LCFAs) (EPO). In each group, half of the mice received FABP4 inhibitor, BMS309403 (1 mg/kg; i.p.) twice a week. Body weight (BW) and food intake were measured; well-established tests were performed to characterize the changes in GI motility and visceral pain. White adipose tissue and colonic samples were collected for cell culturing and molecular studies.

Results

COCO significantly increased GI transit, but not colonic motility. COCO and EPO delayed the onset of diarrhea, but none affected the effect of loperamide. EPO reduced BW and increased the visceromotor response (VMR) to colorectal distension (CRD). COCO and EPO reduced differentiation of preadipocytes. Treatment with BMS309403: (1) reversed the effects induced by COCO in physiological conditions and in mouse models of diarrhea; (2) prevented the effects of EPO on BW, VMR to CRD and castor oil-induced diarrhea; (3) affected proliferation of preadipocytes; (4) changed the expression of Fabp4 in colonic and adipocyte samples from COCO and EPO.

Conclusion

Modifying dietary intake of MCFAs and LCFAs may be used to control GI motility or visceral pain and thus modulate the symptoms of functional GI disorders. The effect is dependent on the expression of FABP4.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-02094-2) contains supplementary material, which is available to authorized users.

Roux Limb Motility in Gastric Bypass Patients with Chronic Abdominal Pain-Is There an Association to Prescribed Opioids?

BACKGROUND/AIM

A number of patients continue to suffer from chronic abdominal pain of unknown origin, which may also lead to a prolonged use of opioid analgesics. Symptoms of abdominal pain, nausea and vomiting in this patient group resemble the characteristics of the Roux stasis Syndrome. The aim was to elucidate relationships between chronic abdominal pain, Roux limb motor activity and opioid analgesics.

METHODS

Roux limb high-resolution manometry and ratings of abdominal pain and quality of life were analysed in 15 gastric bypass patients reporting abdominal pain of unknown origin. Effect of acute opiate administration (morphine i.v.) on fasting Roux limb motor activity was assessed in asymptomatic and morphine-naïve gastric bypass patients (n = 9) and compared with an untreated control group (n = 11).

RESULTS

In the symptomatic patient group, we found disturbed Roux limb motor patterns in 10 out of 15 examinations, but no signs of Roux stasis syndrome. A high prevalence of prescribed opioid analgesics as well as a high number of reoperations in this group. The worst quality of life and the highest number of pain-killing medications were observed among the patients with distal pacemaker activity in Roux limb. In the morphine-naïve and asymptomatic patients, morphine increased the muscular tone in the Roux limb during phase III-like motor activity. A majority of the RYGBP patients with chronic abdominal pain had a disturbed Roux limb fasting motility, and there was a high prevalence of prescribed opioid analgesics. In opiate-naïve RYGBP patients, acute morphine intravenously increased the muscular tone of the Roux limb.

Gastric administration of garlic powder containing the trpa1- agonist allicin induces specific epigastric symptoms and gastric relaxation in healthy subjects

BACKGROUND

TRPA1 is an excitatory ion channel and is involved in sensory processes including thermal nociception and inflammatory pain. The allicin in garlic is a strong activator of the TRPA1 channel.

AIM

To evaluate the effect of intragastric garlic powder containing allicin on perception, gastric tone, and mechanosensitivity.

METHODS

An infusion-barostat balloon assembly was used for infusion of test solutions, for distension, and to measure proximal gastric compliance and tone. After an initial open label dose finding with 1 g, 2 g, 3.75 g, and 7.5 g commercially available garlic powder, a bolus of 2 g garlic powder (11 mg allicin)/60 mL H₂ O was considered to induce moderate but constant sensation and was used hereafter in a placebo-controlled, single-dose, double-blind, randomized study in 7 volunteers to evaluate gastric sensation, tone, and mechanosensitivity.

KEY RESULTS

Bolus injection of garlic caused immediate epigastric symptoms, mean aggregate symptom scores (AUC in 15 minutes) were 106 ± 49 vs. 35 ± 30 after placebo (P = 0.01). Garlic induced significant epigastric pressure, stinging, and warmth (P < 0.01 vs. placebo), while intensity of cramps, satiety, nausea, and pain was not significantly different to placebo (P > 0.05). Garlic induced an immediate, short lived fundic relaxation (balloon volume 627 ± 349 mL vs. -145 ± 120 mL; P < 0.02). No effect of allicin on proximal gastric mechanosensitivity and compliance was observed (NS).

CONCLUSION AND INFERENCES

Garlic containing allicin induces immediate epigastric symptoms of pressure, stinging, and warmth and induces fundic relaxation but does not influence mechanosensitivity or compliance. TRPA1 is a receptor that is involved in gastric sensation and motility.

Identification of Individuals with Functional Dyspepsia With a Simple, Minimally Invasive Test: A Single Center Cohort Study of the Oral Capsaicin Test

OBJECTIVES

The diagnosis of functional dyspepsia (FD) is challenging due to the lack of reliable biological markers to support the diagnosis. We assessed the relevance of a previously validated simple test for chemical hypersensitivity in the setting of a gastrointestinal outpatient department.

METHODS

A total of 224 outpatients who were referred for evaluation of gastrointestinal symptoms in the absence of alarm symptoms swallowed a capsule containing 0.75 mg capsaicin. Severity of symptoms before and after capsule ingestion was assessed by a graded questionnaire and the difference in aggregate symptom scores (delta) was calculated.

RESULTS

Sensitivity of the test was between 0.51-0.59, specificity was 0.84-0.89 and positive predictive value for the diagnosis of FD 70-71%. FD patients had significantly higher median delta symptom scores (10.0; 25% quartile: 3.0; 75% quartile: 16.0) as compared to inflammatory bowel disease (2.5; 1.0/8.5)(P=0.003), peptic ulcer disease (0.0; -1.5/4.5) (P<0.001), irritable bowel syndrome (3.0;0.5/8.5)(P=0.001), and patients classified with "other disease" (2.5;0.0/5.0)(P<0.001). Patients with gastroesophageal reflux disease had significantly lower symptom scores if FD was not concomitantly diagnosed (2.0; 0.0/6.0) than if FD was present (10.0; 4.0/15.0).

CONCLUSIONS

Hypersensitivity for capsaicin discriminates functional dyspepsia from patients with other GI disorders. The capsaicin test is a simple and non invasive method to detect a large subgroup of functional dyspepsia with chemical hypersensitivity. These findings might open new diagnostic options in functional dyspepsia and possibly new therapeutic options by targeting the specific capsaicin receptor TRPV1.

Lack of an Effect of Gastric Capsaicin on the Rectal Component of the Gastrocolonic Response

Luminal capsaicin induces local and distant reflexes in the upper gastrointestinal tract and stimulates lower gastrointestinal symptoms in susceptible persons. We aimed to evaluate the effect of gastric capsaicin on rectal motor function and sensation.

METHODS

Eighteen healthy volunteers participated twice, at least 1 week apart, in this double-blind, placebo-controlled crossover study. Participants swallowed a gastric tube for capsaicin or saline infusion. A barostat tube was placed in the rectum to measure rectal tone before and during gastric capsaicin (40 µg/ml, 2.5 ml/min) or placebo infusion and to conduct distension experiments before and after gastric infusions. Gastric infusions were terminated after 60 min or when epigastric discomfort occurred. Differences in rectal tone, compliance, and sensitivity between gastric placebo and gastric capsaicin were determined.

RESULTS

On both study days, basal rectal volumes, compliance, and sensitivity parameters were comparable (NS) before gastric infusions. Gastric capsaicin infusion induced epigastric discomfort that necessitated termination of infusion after 29.6 ± 12.3 min (saline: 54.7 ± 8.9 min; p < 0.01). Rectal tone, aggregate perception scores, and rectal compliance did not differ between placebo and capsaicin trials (p > 0.05). Rectal tone increased significantly only when capsaicin induced epigastric discomfort (p < 0.05). The reproducibility of the barostat trial was acceptable with significant correlations of volumes, pressures (< 0.05; r ² from 0.41 to 0.55), rectal compliance (p < 0.01; r ² = 0.44), and aggregate perception scores (p values all < 0.05; r ² from 0.44 to 0.0.65) between the two barostat trials.

CONCLUSION

Gastric perfusion with capsaicin does not directly influence rectal physiology through a reflex arc.

Clinical characteristics of functional dyspepsia depending on chemosensitivity to capsaicin

BACKGROUND

Augmented chemosensitivity to capsaicin has been demonstrated in approximately half of functional dyspepsia (FD) patients.

AIM

We determined clinical characteristics of FD patients with and without chemical hypersensitivity at baseline and after capsaicin ingestion for 4 weeks.

METHODS

N=49 outpatients with confirmed FD received an oral sensitivity test with 0.75 mg capsaicin at three occasions, before and after ingesting 0.25 mg capsaicin tid for 4 weeks. Symptomatic response to capsaicin allowed stratification to a capsaicin positive (chemosensitive) and a capsaicin negative (not chemosensitive) patient group. Symptom diaries were completed in the week before and during capsaicin ingestion.

RESULTS

A total of 53% FD had a positive capsaicin test, Crohnbach alpha was 0.85. Basic clinical characteristics were comparable in capsaicin positive and negative FD, but median daily aggregate upper gastrointestinal symptoms scores were significantly higher in capsaicin positive (median: 9.4; 5.4/11.7) than in capsaicin negative patients (6.6; 4.1/8.1) (P<.05). After capsaicin ingestion, upper gastrointestinal symptoms scores were reduced by -3.3 (-4.9/-1.9; P<.001) in capsaicin positive and -2.6 (-3.8/-0.3; P<.05) in capsaicin negative patients. Lower abdominal symptoms were comparable in capsaicin positive and negative patients at baseline (NS). After capsaicin ingestion lower gastrointestinal symptoms scores were reduced by -1.0 (-1.8/-0.1; P<.05) in capsaicin positive but not significantly altered (-0.6; -1.7/+0.9; NS) in capsaicin negative patients. After long-term capsaicin ingestion, the capsaicin test turned negative in 53% of chemosensitive patients (P<.01).

CONCLUSIONS

Differences in upper GI symptoms distinguished capsaicin positive and negative patients. Symptom improvement after long-term capsaicin ingestion was indirect proportional to the capsaicin test result.

A placebo-controlled trial of an oral capsaicin load in patients with functional dyspepsia

BACKGROUND

The pathophysiology of functional dyspepsia is poorly understood. Visceral hypersensitivity may play a key role. We studied a previously validated test to assess chemical hypersensitivity in functional dyspepsia by applying an oral capsaicin load.

METHODS

A total of 116 outpatients with upper gastrointestinal (GI) symptoms participated in this double-blind, placebo-controlled trial of which 73 patients received a final diagnosis of functional dyspepsia. Patients swallowed a capsule containing 0.75 mg capsaicin or placebo. A graded questionnaire evaluated the severity of nine upper GI symptoms before and after capsule ingestion and an aggregate symptom score was calculated. A final score of >9 was considered as a positive test.

KEY RESULTS

In functional dyspepsia, median perception scores were 10.8 (interquartile range: 4.5-18.8) after ingestion of capsaicin and 0.5 (0.0-2.5) after placebo (P < 0.001). Thirty-seven functional dyspepsia patients (54%) had a positive test after capsaicin ingestion, whereas only four (11%) patients with upper GI symptoms but without functional dyspepsia were capsaicin positive [median perception score: 1.5 (0.0-5.0)]. After placebo, symptom scores were low and not significantly different among patient groups (P > 0.05). Clinical characteristics, age, and gender distribution was similar in capsaicin positive and capsaicin negative functional dyspepsia patients (P > 0.05). The value of patient blinding was good.

CONCLUSIONS & INFERENCES

Half of functional dyspepsia patients had chemical hypersensitivity, determined with an oral capsaicin load. Placebo response was negligible. The results of the capsaicin test were not associated with specific dyspepsia symptoms or Rome subgroups.

Is the Roux limb a determinant for meal size after gastric bypass surgery?

The Roux-Y gastric bypass (RYGBP) is an effective weight-reducing procedure but the involved mechanisms of action are obscure. The Roux limb is the intestinal segment that following surgery is the primary recipient for food intake. The aims of the study were to explore the mechanosensory and biomechanical properties of the Roux limb and to make correlations with preferred meal size. Ten patients participated and were examined preoperatively, 6 weeks and 1 year after RYGBP. Each subject ingested unrestricted amounts of a standardized meal and the weight of the meal was recorded. On another study day, the Roux limb was subjected to gradual distension by the use of an intraluminal balloon. Luminal volume–pressure relationships and thresholds for induction of sensations were monitored. At 6 weeks and 1 year post surgery, the subjects had reduced their meal sizes by 62% and 41% (medians), respectively, compared to preoperative values. The thresholds for eliciting distension-induced sensations were strongly and negatively correlated to the preferred meal size. Intraluminal pressure during Roux limb distension, both at low and high balloon volumes, correlated negatively to the size of the meal that the patients had chosen to eat. The results suggest that the Roux limb is an important determinant for regulating food intake after Roux-Y bypass bariatric surgery.

Role of chemical stimulation of the duodenum in dyspeptic symptom generation

The response to chemical stimuli such as acid, nutrients, and capsaicin at the level of the duodenum is increasingly recognized as important in the etiology of dyspeptic symptoms. Increased duodenal acid exposure has been reported for patients with dyspeptic symptoms. Duodenal hypersensitivity to acid and the enhancing effect of duodenal acid on gastroduodenal mechanosensitivity may also contribute to dyspeptic symptom generation. Serotonergic signaling pathways may be involved in acid-induced dyspeptic symptoms. As for nutrients, lipid has been unequivocally shown to have a function in the pathogenesis of dyspeptic symptoms. Cholecystokinin (CCK) is an important mediator of the effects of duodenal lipid on gastroduodenal sensorimotor activities. It is unclear whether CCK hypersecretion or hypersensitivity to CCK is responsible for symptoms in dyspeptic patients. The presence of capsaicin in the duodenum evokes symptoms and affects gastric sensorimotor function. In patients with dyspepsia, capsaicin-induced symptoms appeared to occur earlier and to be more severe, however the effects of duodenal infusion and putative consequent gastric sensorimotor abnormalities have not been examined. Capsaicin activates transient receptor potential ion channel of the vanilloid type I, which can also be activated and sensitized by acid. The interaction between the different chemical stimuli is complex and has not yet been studied in patients with dyspeptic symptoms. In conclusion, the mechanisms underlying an enhanced response to duodenal chemical stimulation in patients with dyspeptic symptoms are partially understood. At the level of the duodenum, abnormalities may exist in stimulus intensity, mucosal mRNA expression, biosynthesis, release, or inactivation of mucosal mediators, or receptor expression on afferent nerve endings. Elucidation of the abnormalities involved will provide a basis for rational treatment of dyspeptic symptoms.

Effect of repeated, long term capsaicin ingestion on intestinal chemo- and mechanosensation in healthy volunteers

Repeated ingestion of capsaicin over a prolonged period reduces symptoms in functional dyspepsia, but initially induces upper abdominal symptoms. Sensitizing chemonociception might be the cause for this initial effect of capsaicin. The aim was to evaluate the effect of prolonged capsaicin ingestion on duodenal chemo- and mechanonociception. Healthy subjects ingested capsules containing either 0.25 mg capsaicin tid (n = 8) or placebo (n = 8) for 28 days. Before (day 0) and after (day 29) capsule ingestion the duodenum was distended with a balloon and perfused with a capsaicin solution. Mechanically and chemically induced sensation was evaluated by a graded questionnaire. Aggregate perception scores were calculated. Perception scores during balloon distensions with 12 and 18 mmHg were significantly lower after 4 weeks capsaicin when compared to baseline (P < 0.05). Balloon volumes to induce first sensation (63 +/- 14 mL (day 0) vs 92 +/- 22 mL (day 29); P < 0.05) and discomfort (101 +/- 12 mL vs 137 +/- 22 mL; P = 0.05) where significantly higher after 4 weeks capsaicin application; balloon pressures to induce sensations were not significantly different. Intraluminal capsaicin application induced first sensation after 3.4 +/- 1.5 min (day 0) and 7.5 +/- 4.6 min (day 29) (P < 0.05) and discomfort after 15.9 +/- 9.8 min and 22.4 +/- 7.3 min (P < 0.05). The quality of perception was not altered by repeated capsaicin ingestion. In the placebo group, mechano- and chemonociception remained unaltered at day 29. Four weeks ingestion of capsaicin desensitized both chemonociceptive and mechanonociceptive pathways in healthy volunteers. Symptom reduction after prolonged treatment with capsaicin in dyspeptic patients might be attributed to a dual desensitizing effect of capsaicin on chemonociceptors and mechanonociceptors.

Duodenal chemosensitivity and mechanosensitivity in humans during acid and ethanol perfusion

INTRODUCTION

Chemical stimulation with capsaicin in the intestinal lumen induces abdominal pain, presumably through a mechanism involving the polymodal vanilloid receptor TRPV1 (transient receptor potential vanilloid receptor subtype 1). Other stimulators of TRPV1 include heat, acid or ethanol. We evaluated the effects of duodenal acid and ethanol exposure on chemosensitivity and mechanosensitivity in healthy volunteers.

METHODS

In two placebo-controlled arms of the study, healthy volunteers received duodenal infusions of either hydrochloric acid (0.1 mol/l) (n=8) or ethanol (5% vol/vol) through an oroduodenal tube. Mechanosensitivity was tested applying pressure-controlled duodenal distensions and chemosensitivity was tested by duodenal perfusion with capsaicin (40 microg/ml; 2.5 ml/min). Quality and intensity of upper abdominal symptoms were evaluated with a graded questionnaire during mechanical and chemical stimulation of the duodenum.

RESULTS

During hydrochloric acid infusion, capsaicin-induced perception was reduced (P<0.01) and latency to discomfort was increased from 24.5 min (25th/75th%:16.5/36 min) during placebo to 50 min (25.5/60 min) (P<0.01). Ethanol had no significant effect on chemosensitivity [latency to discomfort for placebo vs. ethanol: 26 min (18/40 min) vs. 20 min (9/60 min)] (P>0.05). Neither duodenal acidification nor ethanol altered mechanosensitivity significantly (P>0.05).

CONCLUSION

Duodenal acid activated mechanisms that lead to a decreased sensitivity for intraluminal capsaicin; these mechanisms might protect duodenal chemonociceptors from being sensitized by acid. Whether this mechanism is impaired in patients with upper gastrointestinal functional disease remains to be determined.

Hypersensitivity for capsaicin in patients with functional dyspepsia

The pathophysiology of functional dyspepsia is poorly understood, thus diagnostic and therapeutic options for this disease are limited. We assessed the relevance of a simple test for chemical hypersensitivity by applying an oral capsaicin load. After a preliminary dose-finding study, 61 healthy controls and 54 functional dyspepsia patients swallowed a capsule containing 0.75 mg capsaicin. A graded questionnaire evaluated severity of symptoms before and after capsule ingestion; an aggregate symptom score was calculated by adding all symptom scores. Controls developed moderate symptoms (symptom score: 6.0+/-4.1; median: 5.0). The 75% quartile (9.0) was considered the upper limit of normal. Functional dyspepsia patients had significantly higher symptom scores (10.0+/-6.5) than controls. About 54% of functional dyspepsia patients tested positive; clinically this group was not different from the group testing negative besides being on average younger and suffering more from bloating. In additional 13 patients with functional dyspepsia who tested positive (symptom score: 15.8+/-0.9), symptom response to placebo capsules (1.9+/-0.6) was similar to controls. In reliability testing, the Cronbach alpha-value of the capsaicin test was 0.86. The capsaicin test is a simple and non-invasive method to detect a subgroup of functional dyspepsia with chemical hypersensitivity.