Evolving concepts in the cellular control of gastrointestinal motility: neurogastroenterology and enteric sciences

Gut microbiota: a new avenue to reveal pathological mechanisms of constipation

Constipation is very pervasive all over the world. It is a common multifactorial gastrointestinal disease, and its etiology and pathomechanism are not completely clear. Now, increasing evidence shows that intestinal flora is closely related to constipation. Intestinal flora is the largest microbiota in the human body and has powerful metabolic functions. Intestinal flora can produce a variety of metabolites, such as bile acids, short-chain fatty acids, tryptophan metabolites, and methane, which have important effects on intestinal motility and secretion. The host can also monitor the intestinal flora and regulate gut dysbacteriosis in constipation. To explore the relationship between intestinal flora and host, the combination of multiomics technology has become the powerful and effective method. Furthermore, the homeostasis restoration of intestinal flora also provides a new strategy for the treatment of constipation. This review aims to explore the interaction between intestinal flora and host in constipation, which contributes to disclose the pathogenesis of constipation and the development of novel drugs for the treatment of constipation from the perspective of intestinal flora. KEY POINTS: • This review highlights the regulation of gut microbiota on the intestinal motility and secretion of host. • The current review gives an insight into the role of the host on the recognition and regulation of intestinal ecology under constipation. • The article also introduces some novel methods of current gut microbiota research and gut microbiota-based constipation therapies.

Progress in research of gastrointestinal motility regulation

Gastrointestinal motility is an important part of the physiological function of the digestive tract, and its dysfunction is one of the key factors that cause different gastrointestinal motility disorders. These diseases seriously affect patients' normal life. With the development of scientific research and technology, well-designed research studies have been conducted on the regulatory mechanisms of gastrointestinal motility, which mainly include the regulation of gastrointestinal hormones, intestinal microflora, neurotransmitters, brain-gut peptides, interstitial cells of Cajal, and gastrointestinal electrical activities. In addition, current studies have proved that bitter taste receptors have certain regulatory effects on gastrointestinal motility. This paper primarily discusses the relevant pathways controlling gastrointestinal motility.

Intraluminal nutrients acutely strengthen rat intestinal MRP2 barrier function by a glucagon-like peptide-2-mediated mechanism

AIM

MRP2 is an intestinal ABC transporter that prevents the absorption of dietary xenobiotics. The aims of this work were: (1) to evaluate whether a short-term regulation of intestinal MRP2 barrier function takes place in vivo after luminal incorporation of nutrients and (2) to explore the underlying mechanism.

METHODS

MRP2 activity and localization were assessed in an in vivo rat model with preserved irrigation and innervation. Nutrients were administered into distal jejunum. After 30-minutes treatments, MRP2 activity was assessed in proximal jejunum by quantifying the transport of the model substrate 2,4-dinitrophenyl-S-glutathione. MRP2 localization was determined by quantitative confocal microscopy. Participation of extracellular mediators was evaluated using selective inhibitors and by immunoneutralization. Intracellular pathways were explored in differentiated Caco-2 cells.

RESULTS

Oleic acid, administered intraluminally at dietary levels, acutely stimulated MRP2 insertion into brush border membrane. This was associated with increased efflux activity and, consequently, enhanced barrier function. Immunoneutralization of the gut hormone glucagon-like peptide-2 (GLP-2) prevented oleic acid effect on MRP2, demonstrating the participation of this trophic factor as a main mediator. Further experiments using selective inhibitors demonstrated that extracellular adenosine synthesis and its subsequent binding to enterocytic A2B adenosine receptor (A2BAR) take place downstream GLP-2. Finally, studies in intestinal Caco-2 cells revealed the participation of A2BAR/cAMP/PKA intracellular pathway, ultimately leading to increased MRP2 localization in apical domains.

CONCLUSION

These findings reveal an on-demand, acute regulation of MRP2-associated barrier function, constituting a novel physiological mechanism of protection against the absorption of dietary xenobiotics in response to food intake.

Aging-dependent decrease in the numbers of enteric neurons, interstitial cells of Cajal and expression of connexin43 in various regions of gastrointestinal tract

Aging is a significant risk factor for gastrointestinal dysmotility, but aging-associated differences between different organs and the exact time to start degenerating have remained obscure. Here we evaluated alterations of interstitial cells of Cajal, enteric neurons and connexin43 expression in the stomach, jejunum and colon in 2-, 12-, 16-, 20- and 24-month-old mice, as well as in aged human colon. Interstitial cells of Cajal, cholinergic and nitrergic neurons within the whole digestive tract were reduced over time, but their loss first appeared in stomach, then in intestine, helping to understand that gastric function was first impaired during aging. The decrease of connexin43 expression occurred before interstitial cells of Cajal and neurons loss, suggesting that connexin43 might be the major target influenced during senescence. Furthermore, changes in expressions of pro-inflammatory cytokines (tumour necrosis factor-α, interleukin-1β, interleukin-6) and apoptosis-related proteins (B-cell lymphoma-2, caspase-3) which indicated “inflammaging”, might contribute to the loss of enteric neurons and interstitial cells of Cajal in aged gastrointestinal tract. Our results provide possible therapeutic time window for beneficial intervention for geriatric patients with gastrointestinal motility disorders.

Reactive oxygen species overproduction and MAP kinase phosphatase-1 degradation are associated with gastroparesis in a streptozotocin-induced male diabetic rat model

BACKGROUND

Diabetic gastroparesis in human and animal models suggest different developmental causes in females vs males. Previously, we demonstrated that although male and female diabetic gastroparetic rats exhibited similarity in disease pathology, molecular mechanisms were different: slow gastric emptying in male diabetic gastroparetic rats was not associated with the level of expression and dimerization of neuronal nitric oxide synthase α in gastric tissues, as was demonstrated in females. Male gastroparesis may involve other mechanisms, such as oxidative stress. We hypothesize that sustained increased reactive oxygen species (ROS) and degradation of MAP kinase phosphatase-1 with subsequent unregulated activation of c-Jun N-terminal kinase and p38MAP kinase pathways are associated with gastroparesis in a male diabetic rat model.

METHODS

Using a male rat model of diabetic gastroparesis, we analyzed serum and pyloric tissue for ROS and antioxidant enzyme levels using ELISA; MAP kinase phosphatase-1, c-Jun N-terminal kinases, and p38MAP kinase levels utilized western blotting techniques and phospho-specific antibodies.

KEY RESULTS

Both diabetic and diabetic gastroparetic rats demonstrated overproduction of ROS. However, loss of MAP kinase phosphatase-1, a MAP kinase pathway negative regulator, with subsequent activation of c-Jun N-terminal kinase 2 and p38MAP kinase pathways, were observed only in diabetic gastroparetic rats. Diabetic rats without gastroparesis had no significant pathway activation.

CONCLUSIONS & INFERENCES

These results suggest that sustained, increased ROS and degradation of MAP kinase phosphatase-1, with subsequent unregulated activation of c-Jun N-terminal kinase and p38MAP kinase pathways, are likely to be factors in diabetic gastroparesis phenotype in a male diabetic rat model.

The colonic groove of the plains viscacha (Lagostomus maximus): Histochemical evidence of an abrupt change in the glycosylation pattern of goblet cells

The ascending colon of most rodent species shows a longitudinal colonic groove that works as a retrograde transport pathway for a mixture of bacteria and mucus toward the cecum. We describe the morphology and glycosylation pattern of the colonic groove of Lagostomus maximus to analyze the role of mucins in this anatomical feature. We also studied the distribution pattern of the interstitial cells of Cajal (ICC) to evaluate their regulatory influence on gut motility. The groove originated near the cecocolic junction and extended along the mesenteric side of the ascending colon, limited at both ends by nonpapillated ridges. These ridges divided the lumen of the ascending colon into two compartments: a narrow channel and a large channel, called the groove lumen and the main lumen, respectively. The histochemical analysis showed differences in the glycosylation pattern of the goblet cells inside and outside the groove. Unlike the mucosa lining the main lumen of the colon, the groove was rich in goblet cells that secrete sulfomucins. The PA/Bh/KOH/PAS technique evidenced an abrupt change in the histochemical profile of goblet cells, which presented a negative reaction in the groove and a strongly positive one in the rest of the colonic mucosa. The anti-c-kit immunohistochemical analysis showed different ICC subpopulations in the ascending colon of L. maximus. Of all types identified, the ICC-SM were the only cells located solely within the colonic groove.

Intraluminal pressure patterns in the human colon assessed by high-resolution manometry

Assessment of colonic motor dysfunction is rarely done because of inadequate methodology and lack of knowledge about normal motor patterns. Here we report on elucidation of intraluminal pressure patterns using High Resolution Colonic Manometry during a baseline period and in response to a meal, in 15 patients with constipation, chronically dependent on laxatives, 5 healthy volunteers and 9 patients with minor, transient, IBS-like symptoms but no sign of constipation. Simultaneous pressure waves (SPWs) were the most prominent propulsive motor pattern, associated with gas expulsion and anal sphincter relaxation, inferred to be associated with fast propagating contractions. Isolated pressure transients occurred in most sensors, ranging in amplitude from 5–230 mmHg. Rhythmic haustral boundary pressure transients occurred at sensors about 4–5 cm apart. Synchronized haustral pressure waves, covering 3–5 cm of the colon occurred to create a characteristic intrahaustral cyclic motor pattern at 3–6 cycles/min, propagating in mixed direction. This activity abruptly alternated with erratic patterns resembling the segmentation motor pattern of the small intestine. High amplitude propagating pressure waves (HAPWs) were too rare to contribute to function assessment in most subjects. Most patients, dependent on laxatives for defecation, were able to generate normal motor patterns in response to a meal.

G protein-coupled estrogen receptor is involved in modulating colonic motor function via nitric oxide release in C57BL/6 female mice

BACKGROUND

Estrogen may regulate gastrointestinal motor functions, but the mechanism(s) is not totally understood. Here, we investigated whether G protein-coupled estrogen receptor (GPER/GPR30) was involved in regulating colonic motor functions and explored the underlying physiological mechanisms.

METHODS

Adult female C57BL/6 mice were used. The expression and localization of GPER were examined by RT-PCR, western blot, and immuno-labeling. The role of GPER in modulating colonic motor functions was assessed by the bead propulsion test in vivo and organ bath experiments in vitro.

KEY RESULTS

GPER was expressed in colonic myenteric neurons. The colonic transit time (CTT) in proestrus and estrus was significantly longer than that in diestrus. In vivo treatment with the selective GPER blocker G15 significantly shortened CTT in proestrus and estrus. In ovariectomized mice, acute estrogen supplementation increased CTT, which could be abolished by G15 co-administration. The GPER agonist G-1 caused a concentration-dependent inhibition of carbachol -induced circular muscle strips contraction, which was abolished by tetrodotoxin and the neuronal nitric oxide synthase (nNOS) inhibitor N-propyl-l-arginine. G-1 stimulated NO production in isolated longitudinal muscle myenteric plexus and cultured myenteric neurons, which was dependent on nNOS. Immunofluorescence labeling showed co-localization of GPER with nNOS in the myenteric plexus.

CONCLUSIONS & INFERENCES

We suggest that activation of GPER exerts an inhibitory effect on colonic motility by promoting NO release from myenteric nitrergic nerves. These results raise a possibility that GPER may be involved in mediating the inhibitory effect of estrogen on colonic motor functions, via a non-genomic, neurogenic mechanism.

Cellular and Molecular Mechanisms of Phenotypic Switch in Gastrointestinal Smooth Muscle

As a general rule, smooth muscle cells (SMC) are able to switch from a contractile phenotype to a less mature synthetic phenotype. This switch is accompanied by a loss of differentiation with decreased expression of contractile markers, increased proliferation as well as the synthesis and the release of several signaling molecules such as pro-inflammatory cytokines, chemotaxis-associated molecules, and growth factors. This SMC phenotypic plasticity has extensively been investigated in vascular diseases, but interest is also emerging in the field of gastroenterology. It has in fact been postulated that altered microenvironmental conditions, including the composition of microbiota, could trigger the remodeling of the enteric SMC, with phenotype changes and consequent alterations of contraction and impairment of gut motility. Several molecular actors participate in this phenotype remodeling. These include extracellular molecules such as cytokines and extracellular matrix proteins, as well as intracellular proteins, for example, transcription factors. Epigenetic control mechanisms and miRNA have also been suggested to participate. In this review key roles and actors of smooth muscle phenotypic switch, mainly in GI tissue, are described and discussed in the light of literature data available so far. J. Cell. Physiol. 231: 295-302, 2016. © 2015 Wiley Periodicals, Inc.

Effect of colon transection on spontaneous and meal-induced high-amplitude--propagating contractions in children

BACKGROUND

After Hirschsprung disease (HD) surgery, many children experience fecal incontinence caused by increased number of high-amplitude-propagating contractions (HAPCs) through the neorectum to the anal verge. The aim of this study was to determine whether children with HD have more HAPCs than children with colon transections for reasons other than HD.

METHODS

We reviewed 500 colon manometries. Children (age 7.6 ± 5.1 years, 275 boys) with functional constipation (n = 237, age 7.4 ± 5.0 years, 126 boys) and chronic abdominal pain (n = 48, age 9.8 ± 5.8 years, 25 boys) served as controls compared with subjects with HD (n = 56, age 6.9 ± 4.1 years, 44 boys) and colon transection for other reasons (n = 24, age 6.1 ± 5.8 years, 12 boys). We excluded 139 subjects without HAPCs. We documented HAPCs during 1-hour fasting and 1-hour postprandial. Results are in mean ± SD.

RESULTS

During fasting, HD subjects had more HAPCs (2.2 ± 3.4/hour) versus functional constipation (0.8 ± 2.2/hour, P = 0.0004) and chronic pain (0.5 ± 1.1/hour, P = 0.001), but not more than colon transection (1.9 ± 3.2/hour, P = 1.0). HD showed more postprandial HAPCs (4.0 ± 5.4/hour) than functional constipation (1.5 ± 2.5/hour, P < 0.0001) and chronic pain (0.9 ± 1.6/hour, P < 0.0001), but not more than colon transection (2.4 ± 3.0/hour, P = 0.6). There were more HAPCs fasting and postprandial after colon transection (1.9 ± 3.2/hour and 2.4 ± 3.0/hour) than functional constipation (0.8 ± 2.2/hour, P = 0.3 and 1.5 ± 2.5/hour, P = 1.0) and chronic pain (0.5 ± 1.1/hour, P = 1.0 and 0.9 ± 1.6, P = 1.0). HD subjects were divided by chief complaint: fecal incontinence or constipation. HD subjects with incontinence (n = 23) only had more HAPCs fasting (P = 0.01) and postprandial (P = 0.01) than HD subjects with constipation (n = 28) only.

CONCLUSIONS

Increased HAPCs followed colon transection, regardless of a cause. HD subjects with incontinence had more HAPCs than subjects with colon transection for other reasons.

Ca2+ sensitization pathways accessed by cholinergic neurotransmission in the murine gastric fundus

Ca(2+) sensitization of contraction has typically been investigated by bathing muscles in solutions containing agonists. However, it is unknown whether bath-applied agonists and enteric neurotransmission activate similar Ca(2+) sensitization mechanisms. We investigated protein kinase C (PKC)-potentiated phosphatase inhibitor protein of 17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation in murine gastric fundus muscles stimulated by bath-applied carbachol (CCh) or cholinergic motor neurotransmission. CCh increased MYPT1 phosphorylation at Thr696 (pT696) and Thr853 (pT853), CPI-17 at Thr38 (pT38), and myosin light chain at Ser19 (pS19). Electrical field stimulation (EFS) only increased pT38. In the presence of neostigmine, EFS increased pT38, pT853 and pS19. In fundus muscles of W/W(v) mice, EFS alone increased pT38 and pT853. Atropine blocked all contractions and all increases in pT696, pT853, pT38 and pS19. The Rho kinase (ROCK) inhibitor SAR1x blocked increases in pT853 and pT696. The PKC inhibitors Go6976 and Gf109203x or nicardipine blocked increases in pT38 and pT696. These findings suggest that cholinergic motor neurotransmission activates PKC-dependent CPI-17 phosphorylation. Bath-applied CCh recruits additional ROCK-dependent MYPT1 phosphorylation due to exposure of the agonist to a wider population of muscarinic receptors. Intramuscular interstitial cells of Cajal (ICC-IMs) and cholinesterases restrict ACh accessibility to a select population of muscarinic receptors, possibly only those expressed by ICC-IMs. These results provide the first biochemical evidence for focalized (or synaptic-like) neurotransmission, rather than diffuse 'volume' neurotransmission in a smooth muscle tissue. Furthermore, these findings demonstrate that bath application of contractile agonists to gastrointestinal smooth muscles does not mimic physiological responses to cholinergic neurotransmission.

ENDOGLIN/CD105 is expressed in KIT positive cells in the gut and in gastrointestinal stromal tumours

ENDOGLIN/CD105 (ENG) is a transmembrane glycoprotein and an auxiliary unit of the transforming growth factor-β (TGF-β); receptor, expressed predominantly in vascular endothelium. Noteworthy, Eng mRNA expression has been reported also in Kit⁺ interstitial cells of Cajal (ICC) in the mouse intestine. Gastrointestinal stromal tumours (GIST) are thought to derive from ICC. Here we have investigated Eng expression in the Kit^K641E mouse GIST model, in human GIST and in the Ba/F3 cell model. In wild type (WT) mouse antrum, Eng immunoreactivity (-ir) was detected in CD34⁺/CD31⁺ endothelium and in Kit⁺ ICC. In Kit^K641E mice, hyperplasia of Kit⁺ cells made Eng-ir even more evident. Quantitative PCR confirmed the increased expression of Eng transcript in Kit^K641E mice. On human GIST TMA, 26/49 cases stained positive for ENG. Strong ENG staining was associated with malignant and high-risk tumours. ENG negative cases were predominantly of the epithelioid type or harboured PDGFRA mutation. In vitro, Eng mRNA was up-regulated in Ba/F3 cell lines stably expressing various oncogenic Kit mutations (K641E, del559, del814). This effect appeared to be independent of Kit activation, as neither the stimulation of WT Kit by its ligand SCF, nor the inhibition of Kit autophosphorylation by imatinib mesylate in oncogenic mutants, altered Eng expression. Elevated Eng expression in Kit oncogenic mutants appeared rather to be indirectly mediated by DNA hypomethylation, because treatment with the demethylating agent 5-Aza/dC increased Eng mRNA expression in Kit^WT cells. ENG expression in ICC and in GIST deserves further consideration as ENG is emerging as a potential target for cancer therapy.

Control of enteric neuromuscular functions by purinergic A(3) receptors in normal rat distal colon and experimental bowel inflammation

BACKGROUND AND PURPOSE

Adenosine A(3) receptors mediate beneficial effects in experimental colitis, but their involvement in enteric neuromuscular functions during bowel inflammation is undetermined. This study investigated the regulatory role of A(3) receptors on colonic motility in the presence of experimental colitis.

EXPERIMENTAL APPROACH

Colitis was induced in rats by 2,4-dinitrobenzenesulfonic acid. A(3) receptors and adenosine deaminase (ADA, adenosine catabolic enzyme) mRNA were examined by RT-PCR. Tissue distribution of A(3) receptors was detected by confocal immunofluorescence. The effects of 2,3-ethyl-4,5-dipropyl-6-phenylpyridine-3-thiocarboxylate-5-carboxylate (MRS1523) (MRS, A(3) receptor antagonist), 2-chloro-N(6) -(3-iodobenzyl)-adenosine-5'-N-methyluronamide (2Cl-IB-MECA) (CIB, A(3) receptor agonist), dipyridamole (DIP, adenosine transport inhibitor) and ADA were assayed on contractile responses evoked by electrical stimulation (ES) or carbachol in colonic longitudinal muscle preparations (LMP).

KEY RESULTS

RT-PCR showed A(3) receptors and ADA mRNA in normal colon and their increased level in inflamed tissues. Immunofluorescence showed a predominant distribution of A(3) receptors in normal myenteric ganglia and an increased density during colitis. MRS enhanced ES-induced cholinergic contractions in normal LMP, but was less effective in inflamed tissues. After pretreatment with dipyridamole plus ADA, to reduce extracellular adenosine, CIB decreased cholinergic motor responses of normal LMP to ES, with enhanced efficacy in inflamed LMP. A(3) receptor ligands did not affect carbachol-induced contractions in LMP from normal or inflamed colon.

CONCLUSIONS AND IMPLICATIONS

Normally, adenosine modulated colonic cholinergic motility via activation of A(3) receptors in the myenteric plexus. A(3) receptor-mediated tonic inhibitory control by adenosine was impaired in inflamed bowel, despite increased density of functioning and pharmacologically recruitable A(3) receptors.

Kit K641E oncogene up-regulates Sprouty homolog 4 and trophoblast glycoprotein in interstitial cells of Cajal in a murine model of gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GIST) are thought to derive from the interstitial cells of Cajal (ICC) or an ICC precursor. Oncogenic mutations of the receptor tyrosine kinase KIT are present in most GIST. KIT K642E was originally identified in sporadic GIST and later found in the germ line of a familial GIST cohort. A mouse model harbouring a germline Kit K641E mutant was created to model familial GIST. The expression profile was investigated in the gastric antrum of the Kit(K641E) murine GIST model by microarray, quantitative PCR and immunofluorescence. Gja1/Cx43, Gpc6, Gpr133, Pacrg, Pde3a, Prkar2b, Prkcq/Pkce, Rasd2, Spry4 and Tpbg/5T4 were found to be up-regulated. The proteins encoded by Gja1/Cx43, Pde3a, Prkcq/Pkce were localized in Kit-ir ICC in wild-type and Kit(K641E) animals while Spry4 and Tpbg/5T4 were detected in Kit-ir cells only in Kit(K641E), but not in Kit(WT/WT) animals. Most up-regulated genes in this mouse model belong to the gene expression profile of human GIST but also to the profile of normal Kit(+) ICC in the mouse small intestine. Spry4 and Tpbg/5T4 may represent candidates for targeted therapeutic approaches in GIST with oncogenic KIT mutations.

The epidemiology and pathogenesis of neoplasia in the small intestine

PURPOSE

The mucosa of the small intestine encompasses about 90% of the luminal surface area of the digestive system, but only 2% of the total annual gastrointestinal cancer incidence in the United States.

METHODS

The remarkable contrast in age-standardized cancer incidence between the small and large intestine has been reviewed with respect to the cell type patterns, demographic features, and molecular characteristics of neoplasms.

RESULTS

Particularly noteworthy is the predominance of adenocarcinoma in the colon, which exceeds 98% of the total incidence by cell type, in contrast to that of 30% to 40% in the small intestine, resulting in an age-standardized ratio of rates exceeding 50-fold. The prevalence of adenomas and carcinomas is most prominent in the duodenum and proximal jejunum. The positive correlation in global incidence rates of small and large intestinal neoplasms and the reciprocal increases in risk of second primary adenocarcinomas suggest that there are common environmental risk factors. The pathophysiology of Crohn inflammatory bowel disease and the elevated risk of adenocarcinoma demonstrate the significance of the impaired integrity of the mucosal barrier and of aberrant immune responses to luminal indigenous and potentially pathogenic microorganisms.

CONCLUSION

In advancing a putative mechanism for the contrasting mucosal susceptibilities of the small and large intestine, substantial differences are underscored in the diverse taxonomy, concentration and metabolic activity of anaerobic organisms, rate of intestinal transit, changing pH, and the enterohepatic recycling and metabolism of bile acids. Experimental and epidemiologic studies are cited that suggest that the changing microecology, particularly in the colon, is associated with enhanced metabolic activation of ingested and endogenously formed procarcinogenic substrates.

Regulation of enteric functions by adenosine: pathophysiological and pharmacological implications

The wide distribution of ATP and adenosine receptors as well as enzymes for purine metabolism in different gut regions suggests a complex role for these mediators in the regulation of gastrointestinal functions. Studies in rodents have shown a significant involvement of adenosine in the control of intestinal secretion, motility and sensation, via activation of A1, A2A, A2B or A3 purinergic receptors, as well as the participation of ATP in the regulation of enteric functions, through the recruitment of P2X and P2Y receptors. Increasing interest is being focused on the involvement of ATP and adenosine in the pathophysiology of intestinal disorders, with particular regard for inflammatory bowel diseases (IBDs), intestinal ischemia, post-operative ileus and related dysfunctions, such as gut dysmotility, diarrhoea and abdominal discomfort/pain. Current knowledge suggests that adenosine contributes to the modulation of enteric immune and inflammatory responses, leading to anti-inflammatory actions. There is evidence supporting a role of adenosine in the alterations of enteric motor and secretory activity associated with bowel inflammation. In particular, several studies have highlighted the importance of adenosine in diarrhoea, since this nucleoside participates actively in the cross-talk between immune and epithelial cells in the presence of diarrhoeogenic stimuli. In addition, adenosine exerts complex regulatory actions on pain transmission at peripheral and spinal sites. The present review illustrates current information on the role played by adenosine in the regulation of enteric functions, under normal or pathological conditions, and discusses pharmacological interventions on adenosine pathways as novel therapeutic options for the management of gut disorders and related abdominal symptoms.