Michael Schemann

Technische Universität München, München, Bavaria, Germany

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Publications (227)1059.47 Total impact

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    ABSTRACT: Aim: The herbal preparation STW 5 contains fresh plant extracts from bitter candytuft whole plant, extracts from greater celandine herb, angelica root, lemon balm leaves, peppermint leaves, caraway fruit, liquorice root, chamomile flower and milk thistle fruit. We recently reported that STW 5 increased intestinal chloride secretion and proposed that this action may be involved in its clinical efficacy in the treatment of irritable bowel syndrome. The aim of this study was to identify the extracts responsible for the secretory action in order to provide the basis to develop novel target oriented herbal combinations. Methods: We used the Ussing chamber voltage clamp technique to study the effects of individual extracts of STW 5 on short circuit current (Isc, reflecting electrogenic ion transport across epithelial cells) in mucosal/submucosal preparations of human small or large intestinal specimens and the human epithelial cell line T84. Results: STW 5 at concentrations of 512 µg/ml and 5120 µg/ml evoked an increase in Isc. The increase at the lower concentration was due to pro-secretory effects of angelica which were nerve mediated. The increase at the higher concentration was additionally mimicked by peppermint and lemon balm. The remaining extracts did not influence ISC in the large intestine. The results were similar in T84 cells except that angelica had no effect while chamomile induced secretion. These pro-secretory effects were reduced by adenylate cyclase inhibitor MDL-12330A, cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor CFTRinh-172 and calcium activated chloride channels blocker 4-acetamido-4-isothiocyanatostilbene-2,2-disulphonic acid (SITS). Liquorice decreased ISC only in small intestine which was reversed by the epithelial sodium channel blocker amiloride. Conclusions: Results suggested that the pro-secretory action of STW 5 is mainly due to angelica with lesser contribution of peppermint and lemon balm. Their effects involve activation of cAMP- and Ca(++)-activated Cl(-) channels. We suggest that peppermint, lemon balm and in particular angelica may be the basis to develop novel herbal preparations to specifically treat secretory disorder based on impaired epithelial secretion, such as constipation.
    Phytomedicine: international journal of phytotherapy and phytopharmacology 11/2015; 22(12):1063-1070. DOI:10.1016/j.phymed.2015.08.008 · 3.13 Impact Factor
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    Gemma Mazzuoli-Weber · Michael Schemann ·
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    ABSTRACT: For long it was believed that a particular population of enteric neurons, referred to as intrinsic primary afferent neuron (IPAN)s, encodes mechanical stimulation. We recently proposed a new concept suggesting that there are in addition mechanosensitive enteric neurons (MEN) that are multifunctional. Based on firing pattern MEN behaved as rapidly, slowly, or ultra-slowly adapting RAMEN, SAMEN, or USAMEN, respectively. We aimed to validate this concept in the myenteric plexus of the gastric corpus, a region where IPANs were not identified and existence of enteric sensory neurons was even questioned. The gastric corpus is characterized by a particularly dense extrinsic sensory innervation. Neuronal activity was recorded with voltage sensitive dye imaging after deformation of ganglia by compression (intraganglionic volume injection or von Fry hair) or tension (ganglionic stretch). We demonstrated that 27% of the gastric neurons were MEN and responded to intraganglionic volume injection. Of these 73% were RAMEN, 25% SAMEN, and 2% USAMEN with a firing frequency of 1.7 (1.1/2.2), 5.1 (2.2/7.7), and of 5.4 (5.0/15.5) Hz, respectively. The responses were reproducible and stronger with increased stimulus strength. Even after adaptation another deformation evoked spike discharge again suggesting a resetting mode of the mechanoreceptors. All MEN received fast synaptic input. Fifty five percent of all MEN were cholinergic and 45% nitrergic. Responses in some MEN significantly decreased after perfusion of TTX, low Ca++/high Mg++ Krebs solution, capsaicin induced nerve defunctionalization and capsazepine indicating the involvement of TRPV1 expressing extrinsic mechanosensitive nerves. Half of gastric MEN responded to intraganglionic volume injection as well as to ganglionic stretch and 23% responded to stretch only. Tension-sensitive MEN were to a large proportion USAMEN (44%). In summary, we demonstrated for the first time compression and tension-sensitive MEN in the stomach; many of them responded to one stimulus modality only. Their proportions and the basic properties were similar to MEN previously identified by us in other intestinal region and species. Unlike in the intestine, the responsiveness of some gastric MEN is enhanced by extrinsic TRPV1 expressing visceral afferents.
    Frontiers in Cellular Neuroscience 11/2015; 9(342). DOI:10.3389/fncel.2015.00430 · 4.29 Impact Factor
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    ABSTRACT: Knowledge on basic features of epithelial functions in the human intestine is scarce. We used Ussing chamber techniques to record basal tissue resistance (R-basal) and short circuit currents (ISC; secretion) under basal conditions (ISC -basal) and after electrical field stimulation (ISC -EFS) of nerves in 2221 resectates from 435 patients. ISC -EFS was tetrodotoxin-sensitive and of comparable magnitude in small and large intestine. ISC -EFS or R-basal were not influenced by patients´ age, gender or disease pathologies (cancer, polyps, diverticulitis). Ion substitution, bumetanide or adenylate cyclase inhibition studies suggested that ISC -EFS depended on epithelial cAMP-driven chloride and bicarbonate secretion, but not on amiloride-sensitive sodium absorption. While atropine-sensitive cholinergic components prevailed in ISC -EFS of duodenum, jejunum and ileum, PG97-269-sensitive (VIP receptor1 antagonist) VIPergic together with L-NAME-sensitive nitrergic components dominated ISC -EFS in colonic preparations. Differences in numbers of cholinergic or VIPergic neurons, sensitivity of epithelial muscarinic or VIP receptors or stimulus frequency dependent transmitter release were not responsible for the region specific transmitter contribution to ISC -EFS. The low atropine-sensitivity of ISC -EFS in the colon was rather due to high cholinesterase activity because neostigmine revealed cholinergic components. Colonic ISC -EFS remained unchanged after tachykinin, P2X, P2Y or A1/2 receptor blockade. R-basal was smaller but ISC -basal was higher in small intestine. Tetrodotoxin and bumetanide decreased ISC -basal in all regions suggesting nerve-dependent secretory tone. ISC -basal was atropine-sensitive in the small and PG97-269-sensitive in the large intestine. This comprehensive study revealed novel insights into region specific nerve-mediated secretion in human small and large intestine. This article is protected by copyright. All rights reserved.
    The Journal of Physiology 11/2015; DOI:10.1113/JP271493 · 5.04 Impact Factor
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    Gemma Mazzuoli-Weber · Michael Schemann ·
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    ABSTRACT: The enteric nervous system (ENS) autonomously controls gut muscle activity. Mechanosensitive enteric neurons (MEN) initiate reflex activity by responding to mechanical deformation of the gastrointestinal wall. MEN throughout the gut primarily respond to compression or stretch rather than to shear force. Some MEN are multimodal as they respond to compression and stretch. Depending on the region up to 60% of the entire ENS population responds to mechanical stress. MEN fire action potentials after mechanical stimulation of processes or soma although they are more sensitive to process deformation. There are at least two populations of MEN based on their sensitivity to different modalities of mechanical stress and on their firing pattern. (1) Rapidly, slowly and ultra-slowly adapting neurons which encode compressive forces. (2) Ultra-slowly adapting stretch-sensitive neurons encoding tensile forces. Rapid adaptation of firing is typically observed after compressive force while slow adaptation or ongoing spike discharge occurs often during tensile stress (stretch). All MEN have some common properties: they receive synaptic input, are low fidelity mechanoreceptors and are multifunctional in that some serve interneuronal others even motor functions. Consequently, MEN possess processes with mechanosensitive as well as efferent functions. This raises the intriguing hypothesis that MEN sense and control muscle activity at the same time as servo-feedback loop. The mechanosensitive channel(s) or receptor(s) expressed by the different MEN populations are unknown. Future concepts have to incorporate compressive and tensile-sensitive MEN into neural circuits that controls muscle activity. They may interact to control various forms of a particular motor pattern or regulate different motor patterns independently from each other.
    Frontiers in Cellular Neuroscience 10/2015; 9. DOI:10.3389/fncel.2015.00408 · 4.29 Impact Factor
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    ABSTRACT: The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN) is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs) responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs) responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN), slowly (SAMEN), or ultra-slowly (USAMEN). The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut.
    Frontiers in Cellular Neuroscience 09/2015; 9. DOI:10.3389/fncel.2015.00342 · 4.29 Impact Factor
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    ABSTRACT: To characterize pathogenic effects of antibodies to dipeptidyl-peptidase-like protein 6 (DPPX), a subunit of Kv4.2 potassium channels, on gut and brain neurons. We identified a new patient with anti-DPPX encephalitis and analyzed the effects of the patient's serum and purified immunoglobulin G (IgG), and of serum of a previous patient with anti-DPPX encephalitis, on the activity of enteric neurons by voltage-sensitive dye imaging in guinea pig myenteric and human submucous plexus preparations. We studied the subcellular localization of DPPX by immunocytochemistry in cultured murine hippocampal neurons using sera of 4 patients with anti-DPPX encephalitis. We investigated the influence of anti-DPPX-containing serum and purified IgG on neuronal surface expression of DPPX and Kv4.2 by immunoblots of purified murine hippocampal neuron membranes. The new patient with anti-DPPX encephalitis presented with a 2-month episode of diarrhea, which was followed by tremor, disorientation, and mild memory impairment. Anti-DPPX-IgG-containing sera and purified IgG increased the excitability and action potential frequency of guinea pig and human enteric nervous system neurons. Patient sera revealed a somatodendritic and perisynaptic neuronal surface staining that colocalized with the signal of commercial anti-DPPX and Kv4.2 antibodies. Incubation of hippocampal neurons with patient serum and purified IgG resulted in a decreased expression of DPPX and Kv4.2 in neuronal membranes. Hyperexcitability of enteric nervous system neurons and downregulation of DPPX and Kv4.2 from hippocampal neuron membranes mirror the clinical phenotype of patients with anti-DPPX encephalitis and support a pathogenic role of anti-DPPX antibodies in anti-DPPX encephalitis. © 2015 American Academy of Neurology.
    Neurology 08/2015; 85(10). DOI:10.1212/WNL.0000000000001907 · 8.29 Impact Factor
  • D Ostertag · S Bühner · M Götzberger · N Lukas · M Kurjak · C Pehl · M Schemann ·

    Zeitschrift für Gastroenterologie 08/2015; 53(08). DOI:10.1055/s-0035-1559286 · 1.05 Impact Factor
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    ABSTRACT: Innervation interacts with enteric immune responses. Chronic intestinal inflammation is associated with increased risk of colorectal cancer. We aimed to study potential extrinsic neuronal modulation of intestinal tumor development in a mouse model. Experiments were performed with male ApcMin/+ or wild type mice (4 weeks old, body weight approximately 20 g). Subgroups with subdiaphragmatic vagotomy (apcV/wtV), sympathetic denervation of the small intestine (apcS/wtS) or sham operated controls (apcC/wtC) were investigated (n = 6-14 per group). Three months after surgical manipulation, 10 cm of terminal ileum were excised, fixed for 48 h in 4% paraformaldehyde and all tumors were counted and their area determined in mm2 (mean ± standard error of the mean (SEM)). Whole mounts of the muscularis of terminal ileum and duodenum (internal positive control) were also stained for tyrosine hydroxylase to confirm successful sympathetic denervation. Tumor count in ApcMin/+ mice was 62 ± 8 (apcC), 46 ± 11 (apcV) and 54 ± 8 (apcS) which was increased compared to wildtype controls with 4 ± 0.5 (wtC), 5 ± 0.5 (wtV) and 5 ± 0.6 (wtS; all p < 0.05). For ApcMin/+ groups, vagotomized animals showed a trend towards decreased tumor counts compared to sham operated ApcMin/+ controls while sympathetic denervation was similar to sham ApcMin/+. Area covered by tumors in ApcMin/+ mice was 55 ± 10 (apcC), 31 ± 8 (apcV) and 42 ± 8 (apcS) mm2, which was generally increased compared to wildtype controls with 7 ± 0.6 (wtC), 7 ± 0.4 (wtV) and 7 ± 0.6 (wtS) mm2 (all p < 0.05). In ApcMin/+ groups, tumor area was decreased in vagotomized animals compared to sham operated controls (p < 0.05) while sympathetically denervated mice showed a minor trend to decreased tumor area compared to controls. Extrinsic innervation of the small bowel is likely to modulate tumor development in ApcMin/+ mice. Interrupted vagal innervation, but not sympathetic denervation, seems to inhibit tumor growth.
    Journal of Experimental & Clinical Cancer Research 04/2015; 34(1):39. DOI:10.1186/s13046-015-0159-0 · 4.43 Impact Factor

  • Gastroenterology 04/2015; 148(4):S-131. DOI:10.1016/S0016-5085(15)30454-6 · 16.72 Impact Factor
  • Shady Allam · Dagmar Krueger · Eva Maria Kugler · Michael Schemann ·

    Gastroenterology 04/2015; 148(4):S-821. DOI:10.1016/S0016-5085(15)32792-X · 16.72 Impact Factor
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    ABSTRACT: The role of purinergic signaling in the human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. LSCM-Fluo-4-(Ca(2+))-imaging of postsynaptic Ca(2+) transients (PSCaTs) was used as a reporter of neural activity. Synaptic transmission was evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,520 neurons from 241 separate ganglia, 104 patients; immunochemical labeling for P2XRs of neurons in ganglia from 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging was used to test effects of adenosine on fast excitatory synaptic potentials (fEPSPs). Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines. Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50=25μM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50=111nM) in neurons without stimulatory ADPβS responses (EC50=960nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca(2+) transients or Ca(2+) oscillations (EC50=400μM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20nM) or high (5μM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-ir follow the order P2X2>P2X1>P2X3; P2X1+ P2X2 and P2X3+P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1-7,P2Y1,2,12-14R. Responsive neurons were also identified by HuC/D-ir. Purines are critical regulators of neurotransmission in the human enteric nervous system. Purinergic signaling involves P2X1, P2X2, P2X3 channels, P2X1+P2X2 co-localization and inhibitory P2Y or A3 receptors. These are potential novel therapeutic targets for neurogastroenterology. Published by Elsevier Ltd.
    Neuropharmacology 02/2015; 95. DOI:10.1016/j.neuropharm.2015.02.014 · 5.11 Impact Factor
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    ABSTRACT: Based on the discomfort/pain threshold during rectal distension, Irritable Bowel Syndrome (IBS) patients may be subtyped as normo- or hypersensitive. We previously showed that mucosal biopsy supernatants from IBS patients activated enteric and visceral afferent neurons. We tested the hypothesis that visceral sensitivity is linked to the degree of neuronal activation. Normo- and hypersensitive IBS patients were distinguished by their discomfort/pain threshold to rectal balloon distension with a barostat. Using potentiometric and Ca(2+) dye imaging, we recorded the response of guinea pig enteric submucous and mouse dorsal root ganglion (DRG) neurons, respectively, to mucosal biopsy supernatants from normosensitive (n = 12 tested in enteric neurons, n = 9 tested in DRG) and hypersensitive IBS (n = 9, tested in both types of neurons) patients. In addition, we analyzed the association between neuronal activation and individual discomfort/pain pressure thresholds. IBS supernatants evoked Ca(2+) transients in DRG neurons and spike discharge in submucous neurons. Submucous and DRG neurons showed significantly stronger responses to supernatants from hypersensitive IBS patients as reflected by higher spike frequency or stronger [Ca(2+)]i transients in a larger proportion of neurons. The neuroindex as a product of spike frequency or [Ca(2+)]i transients and proportion of responding neurons significantly correlated with the individual discomfort/pain thresholds of the IBS patients. Supernatants from hypersensitive IBS patients caused stronger activation of enteric and DRG neurons. The level of activation correlated with the individual discomfort/pain threshold pressure values. These findings support our hypothesis that visceral sensitivity is linked to activation of peripheral neurons by biopsy supernatants. This article is protected by copyright. All rights reserved.
    Experimental physiology 06/2014; 99(10). DOI:10.1113/expphysiol.2014.080036 · 2.67 Impact Factor
  • Michel Neunlist · Michael Schemann ·
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    ABSTRACT: The enteric nervous system (ENS) integrates numerous sensory signals in order to control and maintain normal gut functions. Nutrients are one of the prominent factors which determine the chemical milieu in the lumen and, after absorption, also within the gut wall. This topical review summarizes current knowledge on the impact of key nutrients on ENS functions and phenotype, covering their acute and long-term effects. Enteric neurones contain the molecular machinery to respond specifically to nutrients. These transporters and receptors are not expressed exclusively in the ENS but are also present in other cells such as enteroendocrine cells (EEC) and extrinsic sensory nerves, signalling satiety or hunger. Glucose, amino acids and fatty acids all activate enteric neurones, as suggested by enhanced c-Fos expression or spike discharge. These excitatory effects are the result of a direct neuronal activation but also involve activation of EEC which, upon activation by luminal nutrients, release mediators such as ghrelin, cholecystokinin or serotonin. The presence or absence of nutrients in the intestinal lumen induces long-term changes in neurotransmitter expression, excitability, neuronal survival and ultimately impact upon gut motility, secretion or intestinal permeability. Together with EEC and vagal nerves, the ENS must be recognized as an important player initiating concerted responses to nutrients. It remains to be studied how, for instance, nutrient-induced changes in the ENS may influence additional gut functions such as intestinal barrier repair, intestinal epithelial stem cell proliferation/differentiation and also the signalling of extrinsic nerves to brain regions which control food intake. This article is protected by copyright. All rights reserved.
    The Journal of Physiology 06/2014; 592(14). DOI:10.1113/jphysiol.2014.272948 · 5.04 Impact Factor

  • Gastroenterology 05/2014; 146(5):S-82-S-83. DOI:10.1016/S0016-5085(14)60296-1 · 16.72 Impact Factor
  • Y Nasser · G E Boeckxstaens · M M Wouters · M Schemann · S Vanner ·
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    ABSTRACT: Although animal models of the irritable bowel syndrome (IBS) have provided important insights, there are no models that fully express the features of this complex condition. One alternative approach is the use of human intestinal biopsies obtained during endoscopic procedures to examine peripheral mechanisms in this disorder. These studies have served to confirm the existence of peripheral pathways in humans with IBS and have provided many new mechanistic insights. Two general approaches have been employed; one approach has been to examine the biological activity of mediators within the mucosal tissue of IBS patients and the other has been to examine changes in the structural properties of key signaling pathways contained within the biopsies. Using these approaches, important changes have been discovered involving the enteric nervous system and the extrinsic sensory pathway (dorsal root ganglia neurons), the immune system, and epithelial signaling in IBS patients compared to healthy subjects. This review will systematically explore these mechanistic pathways, highlight the implications of these novel findings and discuss some of the important limitations of this approach.
    Neurogastroenterology and Motility 02/2014; 26(4). DOI:10.1111/nmo.12316 · 3.59 Impact Factor
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    ABSTRACT: Objectives: Abnormal pain perception or visceral hypersensitivity (VH) is considered to be an important mechanism underlying symptoms in a subgroup of irritable bowel syndrome (IBS) patients. Increased TRPV1 (transient receptor potential cation channel subfamily V member 1) expression in rectal biopsies of IBS patients suggests a potentially important role for this nociceptor in the pathophysiology of IBS. However, evidence underscoring the involvement of TRPV1 in visceral perception in IBS is lacking. The objective of this study was to evaluate the role of TRPV1 in VH to rectal distension and clinical symptoms in patients with IBS. Methods: A total of 48 IBS patients and 25 healthy volunteers (HVs) were invited to undergo subsequent assessment of sensitivity to rectal distensions and rectal capsaicin applications. Visceral sensitivity was evaluated by rectal distension at 3, 9, and 21 mm Hg above minimal distension pressure (MDP). Capsaicin was applied to the rectal mucosa (0.01%, 0.1%, or solvent only in random order). Visceral sensations (urge to defecate, pain, burning, and warmth sensation) were scored on a 100-mm visual analog scale (VAS). TRPV1 expression in rectal biopsies was determined by immunohistochemistry and real-time PCR. Results: A total of 23 IBS patients (48%) were hypersensitive to rectal distensions (VH-IBS). A concentration-dependent increase of urge and pain perception was present in HVs and IBS patients during capsaicin 0.01 and 0.1% applications. VH-IBS patients experienced a significantly increased perception of pain, but not urge, during capsaicin applications compared with normosensitive patients (ns-IBS) and HVs. Increased pain perception was significantly associated with anxiety and VH, symptoms scores of abdominal pain, loose stools, and stool frequency. Anxiety experienced during the experimental procedure was enhanced in VH-IBS patients but not in ns-IBS or HVs. However, rectal TRPV1 expression was similar in VH-IBS, ns-IBS, and HVs on both mRNA and protein expression levels. TRPV1 expression levels did not correlate with pain perception to capsaicin or clinical symptoms in IBS patients or the subgroups. Conclusions: IBS patients with VH to rectal distension reveal increased pain perception to rectal application of capsaicin, as well as an increased anxiety response. No evidence for TRPV1 upregulation could be demonstrated. As both VH and anxiety are independently associated with increased pain perception to rectal capsaicin application, our data suggest that both peripheral and central factors are involved, with increased receptor sensitivity as a speculative possibility.
    The American Journal of Gastroenterology 11/2013; 109(1). DOI:10.1038/ajg.2013.371 · 10.76 Impact Factor
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    ABSTRACT: The cholinergic anti-inflammatory pathway is an endogenous mechanism by which the autonomic nervous system attenuates macrophage activation via nicotinic acetylcholine receptors (nAChR). This concept has however not been demonstrated at a cellular level in intact tissue. To this end, we have studied the effect of nicotine on the activation of resident macrophages in a mouse stomach preparation by means of calcium imaging. Calcium transients ([Ca(2+)]i) in resident macrophages were recorded in a mouse stomach preparation containing myenteric plexus and muscle layers by Fluo-4. Activation of macrophages was achieved by focal puff administration of ATP. The effects of nicotine on activation of macrophages were evaluated and the nAChR involved was pharmacologically characterized. The proximity of cholinergic nerves to macrophages was quantified by confocal microscopy. Expression of β2 and α7 nAChR was evaluated by β2 immunohistochemistry and fluorophore-tagged α-bungarotoxin. In 83% of macrophages cholinergic varicose nerve fibers were detected at distances <900nm. The ATP induced [Ca(2+)]i increase was significantly inhibited in 65% or 55% of macrophages by 100µM or 10µM nicotine, respectively. This inhibitory effect was reversed by the β2 nAChR preferring antagonist dihydro-β-eryhtroidine but not by hexamethonium (non-selective nAChR-antagonist), mecamylamine (α3β4 nAChR-preferring antagonist), α-bungarotoxin or methyllycaconitine (both α7 nAChR-preferring antagonist). Macrophages in the stomach express β2 but not α7 nAChR at protein level, while those in the intestine express both receptor subunits. This study is the first in situ demonstration of an inhibition of macrophage activation by nicotine suggesting functional signaling between cholinergic neurons and macrophages in the stomach. The data suggest that the β2 subunit of the nAChR is critically involved in the nicotine-induced inhibition of these resident macrophages.
    PLoS ONE 11/2013; 8(11):e79264. DOI:10.1371/journal.pone.0079264 · 3.23 Impact Factor
  • T. Frieling · M. Schemann ·
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    ABSTRACT: Das Reizdarmsyndrom (RDS) ist einer der häufigsten Gründe, warum Patienten den Arzt aufsuchen, und stellt hierdurch eine erhebliche sozioökonomische Belastung dar. Das RDS wurde aufgrund der geschichtlichen Entwicklung bisher symptomenbasiert definiert. Diese symptomenbasierte Definition durch Symptomencluster als Krankheit ist problematisch, da sich das hierdurch definierte Patientenkollektiv bezüglich des Krankheitsverlaufs nicht grundsätzlich von anderen Erkrankungen unterscheidet. Neuere Untersuchungen zeigen, dass das RDS mit verschiedenen strukturellen, molekularen, genetischen, immunologischen, nervalen und psychosozialen Veränderungen assoziiert ist. Die vielen heute diskutierten Pathomechanismen spiegeln zum einen den multifaktoriellen Charakter des RDS wider, sind zum anderen aber auch Hinweise auf pathophysiologisch unterschiedliche Erkrankungen. Es ist zu erwarten, dass in Zukunft die weitere Aufklärung pathophysiologisch relevanter Faktoren und insbesondere deren Korrelation mit den klinischen Symptomen die Diagnostik und Therapie des Reizdarmsyndroms verbessert. Es wird ein wesentliches Ziel sein, Biomarker zur Charakterisierung der zahlreichen RDS-Untergruppen zu finden, damit eine spezifische Therapieentscheidung möglich ist.
    Der Gastroenterologe 09/2013; 8(5). DOI:10.1007/s11377-013-0782-2
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    BMC pharmacology & toxicology 08/2013; 14(Suppl 1):O30-O30. DOI:10.1186/2050-6511-14-S1-O30
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    BMC pharmacology & toxicology 08/2013; 14(Suppl 1):P34-P34. DOI:10.1186/2050-6511-14-S1-P34

Publication Stats

5k Citations
1,059.47 Total Impact Points


  • 2003-2015
    • Technische Universität München
      • Chair of Human Biology
      München, Bavaria, Germany
  • 2013
    • Catholic University of Louvain
      Лувен-ла-Нев, Walloon, Belgium
  • 2009
    • University of Bristol
      Bristol, England, United Kingdom
  • 1995-2002
    • University of Veterinary Medicine Hannover
      • Institute of Physiology
      Hanover, Lower Saxony, Germany
    • The University of Sheffield
      • Department of Biomedical Science
      Sheffield, ENG, United Kingdom
    • Bulgarian Academy of Sciences
      Ulpia Serdica, Sofia-Capital, Bulgaria
  • 2001
    • University of Tuebingen
      Tübingen, Baden-Württemberg, Germany
  • 1994-2001
    • Heinrich-Heine-Universität Düsseldorf
      • Klinik für Gastroenterologie, Hepatologie und Infektiologie
      Düsseldorf, North Rhine-Westphalia, Germany
  • 1995-1999
    • Hochschule Hannover
      Hanover, Lower Saxony, Germany
  • 1984-1992
    • Hohenheim University
      • Institute of Physiology
      Stuttgart, Baden-Württemberg, Germany
  • 1986-1989
    • The Ohio State University
      • • Department of Physiology and Cell Biology
      • • College of Medicine
      Columbus, Ohio, United States