Identification and molecular study on the interaction of Schisandrin C with human 5-HT3A receptor.

Schisandrin C (Sch C) is one of the main components of Schisandra chinensis (Schisandra). Since the olden times, Schisandra has been used as a traditional herbal medicine in Asia. Recent studies have shown that Schisandra is effective against irritable bowel syndrome (IBS) in an animal model and affects IBS through the 5-HT3A pathway in the IBS rat model. However, there lacks fundamental research on the interaction of specific components of Schisandra with the 5-HT3A receptor for the treatment of IBS. We hypothesized that a component of Schisandra binds to the 5-HT3A receptor and identified Sch C via a screening work using two electrode-voltage clamps (TEVC). Thus, we aimed to elucidate the neuropharmacological actions between Sch C and the 5-HT3A receptor at molecular and cellular levels. Co-treatment of Sch C with 5-HT inhibited I5-HT in a reversible, concentrate-dependent, like-competition, and voltage-independent manner, and IC50 values of Sch C. Besides, the main binding positions of Sch C were identified through 3D modeling and point mutation were V225A and V288Y on 5-HT3A receptor. Thus, we suggest the potential of Sch C in treating IBS in a manner that suppresses excessive neuronal serotonin signaling in the synapse of sensory neurons and enterochromaffin (EC) cells. In conclusion, the results demonstrate the mechanism of interaction between Sch C and 5-HT3A receptor and reveal Sch C as a novel antagonist.

Neuronal innervation of the intestinal crypt.

Mucosal damage is a key feature of inflammatory bowel diseases (IBD) and healing of the mucosa is an endpoint of IBD treatment that is often difficult to achieve. Autonomic neurons of the parasympathetic and sympathetic nervous system may influence intestinal epithelial cell growth and modulating epithelial innervation could for that reason serve as an interesting therapeutic option to improve mucosal healing. Understanding of the biological processes triggered by nonspecific and specific epithelial adrenergic and cholinergic receptor activation is of key importance. At present, with rising technological advances, bioelectronic neuromodulation as treatment modality has gained momentum. We discuss the current view on state-of-the-art innervation of the intestinal crypt and its impact on epithelial cell growth and differentiation. Furthermore, we outline bioelectronic technology and review its relevance to wound healing processes.

Ginger and 6-shogaol protect intestinal tight junction and enteric dopaminergic neurons against 1-methyl-4-phenyl 1,2,3,6-tetrahydropyridine in mice.

Objective: Ginger and its compound, 6-shogaol, have been known for improving gastrointestinal (GI) function and reducing inflammatory responses in GI tract. Recently, the treatment of GI dysfunction has been recognized as an important part of the management of neurodegenerative diseases, especially for Parkinson's disease (PD). In this study, we investigated whether ginger and 6-shogaol attenuate disruptions induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on the intestinal barrier and the enteric dopaminergic neurons.Methods: C57BL/6J mice received MPTP (30 mg/kg) for 5 days to induce GI alterations. Ginger (30, 100, 300 mg/kg) and 6-shogaol (10 mg/kg) were treated by gavage feeding for 15 days including the period of MPTP injection.Results: Ginger and 6-shogaol protected intestinal tight junction proteins disrupted by MPTP in mouse colon. In addition, ginger and 6-shogaol suppressed the increase of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α and IL-1ß activated by macrophage. Moreover, ginger and 6-shogaol suppressed the MPTP-induced enteric dopaminergic neuronal damage via increasing the cell survival signaling pathway.Conclusion: These results indicate that ginger and 6-shogaol restore the disruption of intestinal integrity and enteric dopaminergic neurons in an MPTP-injected mouse PD model by inhibiting the processes of inflammation and apoptosis, suggesting that they may attenuate the GI dysfunction in PD patients.

Inflammatory Bowel Disease: A Stressed "Gut/Feeling".

Inflammatory bowel disease (IBD) is a chronic and relapsing intestinal inflammatory condition, hallmarked by a disturbance in the bidirectional interaction between gut and brain. In general, the gut/brain axis involves direct and/or indirect communication via the central and enteric nervous system, host innate immune system, and particularly the gut microbiota. This complex interaction implies that IBD is a complex multifactorial disease. There is increasing evidence that stress adversely affects the gut/microbiota/brain axis by altering intestinal mucosa permeability and cytokine secretion, thereby influencing the relapse risk and disease severity of IBD. Given the recurrent nature, therapeutic strategies particularly aim at achieving and maintaining remission of the disease. Alternatively, these strategies focus on preventing permanent bowel damage and concomitant long-term complications. In this review, we discuss the gut/microbiota/brain interplay with respect to chronic inflammation of the gastrointestinal tract and particularly shed light on the role of stress. Hence, we evaluated the therapeutic impact of stress management in IBD.

Capsaicin alleviates abnormal intestinal motility through regulation of enteric motor neurons and MLCK activity: Relevance to intestinal motility disorders.

SCOPE: Capsaicin is an active component of chili peppers, having diverse effects. However, the effects of capsaicin on intestinal motility are still controversial. The present study aimed to investigate the effects of capsaicin on intestinal motility disorder and uncover related mechanisms. MATERIALS AND RESULTS: A rat model with intestinal motility disorder was established in vitro through adding different stimuli into tissue bath; in vivo using constipation and diarrhea model, respectively. Capsaicin exerted dual effects on intestinal motility, i.e. the relaxation and contraction of jejunum induced by corresponding stimulus were, respectively, regulated to be normal contraction by capsaicin. The mechanisms underlined capsaicin-induced dual effects were investigated using Western blotting, qRT-PCR, and whole-cell patch clamp, respectively. Results showed that cholinergic excitatory nerves, adrenergic nerves, and neurons containing nitric oxide synthase, which are the main muscle motor neurons in enteric nervous system (ENS), are involved in capsaicin-induced dual effects. The competition for regulation of Ca(2+) influx by capsaicin induced the interaction with components of the ENS. Capsaicin significantly increased myosin light chain kinase (MLCK) expression and myosin phosphorylation extent in jejunal segments of constipation-prominent rats and significantly decreased MLCK expression and myosin phosphorylation extent in jejunal segments of diarrhea-prominent rats. CONCLUSION: In summary, capsaicin alleviates abnormal intestinal motility through regulating enteric motor neurons and MLCK activity, which is beneficial for the treatment of gastrointestinal motility disorders.

Alterations in serotonin, transient receptor potential channels and protease-activated receptors in rats with irritable bowel syndrome attenuated by Shugan decoction.

AIM: To determine the molecular mechanisms of Shugan decoction (SGD) in the regulation of colonic motility and visceral hyperalgesia (VHL) in irritable bowel syndrome (IBS). METHODS: The chemical compounds contained in SGD were measured by high-performance liquid chromatography. A rat model of IBS was induced by chronic water avoidance stress (WAS). The number of fecal pellets was counted after WAS and the pain pressure threshold was measured by colorectal distension. Morphological changes in colonic mucosa were detected by hematoxylin-eosin staining. The contents of tumor necrosis factor (TNF)-α in colonic tissue and calcitonin-gene-related peptide (CGRP) in serum were measured by ELISA. The protein expression of serotonin [5-hydroxytryptamide (5-HT)], serotonin transporter (SERT), chromogranin A (CgA) and CGRP in colon tissue was measured by immunohistochemistry. RESULTS: SGD inhibited colonic motility dysfunction and VHL in rats with IBS. Blockers of transient receptor potential (TRP) vanilloid 1 (TRPV1) (Ruthenium Red) and TRP ankyrin-1 (TRPA1) (HC-030031) and activator of protease-activated receptor (PAR)4 increased the pain pressure threshold, whereas activators of PAR2 and TRPV4 decreased the pain pressure threshold in rats with IBS. The effect of SGD on pain pressure threshold in these rats was abolished by activators of TRPV1 (capsaicin), TRPV4 (RN1747), TRPA1 (Polygodial) and PAR2 (AC55541). In addition, CGRP levels in serum and colonic tissue were both increased in these rats. TNF-α level in colonic tissue was also significantly upregulated. However, the levels of 5-HT, SERT and CgA in colonic tissue were decreased. All these pathological changes in rats with IBS were attenuated by SGD. CONCLUSION: SGD alleviated VHL and attenuated colon motility in IBS, partly by regulating TRPV1, TRPV4, TRPA1, PAR2, 5-HT, CgA and SERT, and reducing CGRP and TNF-α level.

Dietary Marine n-3 PUFAs Do Not Affect Stress-Induced Visceral Hypersensitivity in a Rat Maternal Separation Model.

BACKGROUND: Although never evaluated for efficacy, n-3 (ω-3) long-chain polyunsaturated fatty acids (LCPUFAs) are commercially offered as treatment for irritable bowel syndrome (IBS). OBJECTIVE: This study was designed to investigate, in a mast cell-dependent model for visceral hypersensitivity, whether this pathophysiologic mechanism can be reversed by dietary LCPUFA treatment via peroxisome proliferator-activated receptor γ (PPARG) activation. METHODS: Maternally separated rats were subjected to hypersensitivity-inducing acute stress at adult age. Reversal was attempted by protocols with tuna oil-supplemented diets [4% soy oil (SO) and 3% tuna oil (SO-T3) or 3% SO and 7% tuna oil (SO-T7)] and compared with control SO diets (7% or 10% SO) 4 wk after stress. The PPARG agonist rosiglitazone was evaluated in a 1 wk preventive protocol (30 mg · kg⁻¹ · d⁻¹). Erythrocytes were assessed to confirm LCPUFA uptake and tissue expression of lipoprotein lipase and glycerol kinase as indicators of PPARG activation. Colonic mast cell degranulation was evaluated by toluidine blue staining. In vitro, human mast cell line 1 (HMC-1) cells were pretreated with rosiglitazone, eicosapentaenoic acid, or docosahexaenoic acid, stimulated with phorbol 12-myristate 13-acetate (PMA) and calcium ionophore or compound 48/80 and evaluated for tumor necrosis factor α (TNF-α) and ß-hexosaminidase release. RESULTS: Stress led to visceral hypersensitivity in all groups. Hypersensitivity was not reversed by SO-T3 or control treatment [prestress vs. 24 h poststress vs. posttreatment area under the curve; 76 ± 4 vs. 128 ± 12 (P < 0.05) vs. 115 ± 14 and 82 ± 5 vs. 127 ± 16 (P < 0.01) vs. 113 ± 19, respectively]. Comparison of SO-T7 with its control showed similar results [74 ± 6 vs. 103 ± 13 (P < 0.05) vs. 115 ± 17 and 66 ± 3 vs. 103 ± 10 (P < 0.05) vs. 117 ± 11, respectively]. Erythrocytes showed significant LCPUFA uptake in the absence of colonic PPARG activation. Rosiglitazone induced increased PPARG target gene expression, but did not prevent hypersensitivity. Mast cell degranulation never differed between groups. Rosiglitazone and LCPUFAs significantly reduced PMA/calcium ionophore-induced TNF-α release but not degranulation of HMC-1 cells. CONCLUSION: Dietary LCPUFAs did not reverse stress-induced visceral hypersensitivity in maternally separated rats. Although further research is needed, claims concerning LCPUFAs as a treatment option in IBS cannot be confirmed at this point and should be regarded with caution.

A fatty gut feeling.

The absorptive epithelium of the proximal small intestine converts oleic acid released during fat digestion into oleoylethanolamide (OEA), an endogenous high-affinity agonist of peroxisome proliferator-activated receptor-α (PPAR-α). OEA interacts with this receptor to cause a state of satiety characterized by prolonged inter-meal intervals and reduced feeding frequency. The two main branches of the autonomic nervous system, sympathetic and parasympathetic, contribute to this effect: the former by enabling OEA mobilization in the gut and the latter by relaying the OEA signal to brain structures, such as the hypothalamus, that are involved in feeding regulation. OEA signaling may be a key component of the physiological system devoted to the monitoring of dietary fat intake, and its dysfunction might contribute to overweight and obesity.

Effects of peripherally and centrally applied ghrelin in the pathogenesis of ischemia-reperfusion induced injury of the small intestine.

Ghrelin is an important hormone involved in the control of the human appetite center. Recently, protective properties of this hormone have been recognized in various models of impairment of the gastric mucosa, including stress, ischemia and reperfusion (I/R). Ghrelin is predominantly secreted by the gastric mucosa of stomach, but there are other sources of ghrelin, for example in the hypothalamus and various parts of the central nervous system (CNS) that should be taken into consideration. This hormone exerts biological effects via the activation of growth hormone secretagogue receptor (GHSR), the presence of which was confirmed in different parts of the gastrointestinal (GI) tract and midbrain structures. Although substantial evidence of the divergent biological effects of ghrelin and the mechanism of its action has been emphasized, the precise mechanisms of ghrelin which affords GI protection is still unclear. Particularly, there is a sparse amount of evidence concerning its action on the GI system. The major aim of the present study was to evaluate the importance of peripherally and centrally administered ghrelin at different times of the ischemia and reperfusion (I/R period in the modulation of resistance of the intestinal mucosa to the injury induced by ischemia and subsequent reperfusion. Secondly, we wanted to evaluate the possible mechanism of the action of ghrelin with a particular focus on its influence on the intestinal blood flow. Male Wistar rats were divided into 4 series (A-D) of the experimental groups (n=7). In series A the importance of peripherally administered ghrelin at different time of I/R period was studied. In series B the importance of centrally administered ghrelin at different time of I/R period was evaluated. In series C and D, the mechanisms of peripherally and centrally administered hormone were examined, respectively. Two models of the I/R period were selected: short lasting (30/60 min) and long lasting (60/120 min). The following drugs were used: ghrelin (50 µg/kg i.p. or 1 nmol in 10 µl i.c.v.), 6 hydroxy dopamine (50 mg/kg i.p.), nadolol (0.5 mg/kg i.p.), calcitonin gene related peptide fragment (CGRP(8-37), 100 µg /kg i.p.), capsaicin (5-10 mg/100 ml solution s.c.). The mesenteric blood flow (MBF-ml/min), the intestinal microcirculatory blood flow (LDBF-PU), the arterio-venous oxygen difference (AVO(2)-ml/O(2)/100 ml blood), and the intestinal oxygen uptake (VO(2)) in ml O(2)/min were measured. Mucosal impairment was assessed planimetrically with the use of a digital photo analyzer (LA) and histologically with the use of the six-point Park/Chiu scale. Peripheral administration of ghrelin evoked marked increase of MBF and LDBF by 42% and 48%, respectively, with significant reduction of LA by 38%. When ghrelin was administered at the beginning of the reperfusion period during the short I/R period or prior to the long lasting I/R period, the vascular reactions and protective effects were reduced, but not completely abolished. The central administration of ghrelin before the short I/R period significantly increased the MBF and LDBF by about 32% and 35%, respectively, as well as LA reduction by about 20% in comparison to the control group. However, when ghrelin was administered prior to the long I/R period or after the onset of completed ischemia, neither vascular nor protective effects were noticed. Sensory denervation and the blockade of the CGRP1 receptors totally blocked the protective and hyperemic effects of the peripherally administered ghrelin. Selective blockade of the adrenergic system or blunting of the vagal nerves (vagotomy) significantly but not totally eliminated the effects of centrally applied ghrelin, which were abolished when both adrenergic and parasympathetic pathways were ablated. These results indicate that ghrelin applied centrally or peripherally markedly increases resistance of the intestinal tissue during the I/R period induced mucosal and hyperemic impairment evoked by I/R. Ghrelin is an important mediator of the increase in the intestinal microcirculation and elevation of the intestinal metabolism, which seems to be, at least in part, responsible for the observed protection of the intestine subjected to I/R. Impairment of this microvasculature response due to I/R seems to be responsible for a markedly observed weaker effect of ghrelin when this hormone was administered after the ischemic period. The lack of a protective effect observed after central administration of this peptide against a long lasting I/R period is probably due to damage of neural pathways caused by I/R. Finally, the peripheral activity of ghrelin in the intestine is mediated by the sensory neurons with a prominent role of CGRP released from their endings. However, this peripheral action of ghrelin depends upon the proper functioning of both the sympathetic and parasympathetic system.

Enteric glia protect against Shigella flexneri invasion in intestinal epithelial cells: a role for S-nitrosoglutathione.

BACKGROUND: Enteric glial cells (EGCs) are important regulators of intestinal epithelial barrier (IEB) functions. EGC-derived S-nitrosoglutathione (GSNO) has been shown to regulate IEB permeability. Whether EGCs and GSNO protect the IEB during infectious insult by pathogens such as Shigella flexneri is not known. METHODS: S flexneri effects were characterised using in vitro coculture models of Caco-2 cells and EGCs (or GSNO), ex vivo human colonic mucosa, and in vivo ligated rabbit intestinal loops. The effect of EGCs on S flexneri-induced changes in the invasion area and the inflammatory response were analysed by combining immunohistochemical, ELISA and PCR methods. Expression of small G-proteins was analysed by western blot. Expression of ZO-1 and localisation of bacteria were analysed by fluorescence microscopy. RESULTS: EGCs significantly reduced barrier lesions and inflammatory response induced by S flexneri in Caco-2 monolayers. The EGC-mediated effects were reproduced by GSNO, but not by reduced glutathione, and pharmacological inhibition of pathways involved in GSNO synthesis reduced EGC protecting effects. Furthermore, expression of Cdc42 and phospho-PAK in Caco-2 monolayers was significantly reduced in the presence of EGCs or GSNO. In addition, changes in ZO-1 expression and distribution induced by S flexneri were prevented by EGCs and GSNO. Finally, GSNO reduced S flexneri-induced lesions of the IEB in human mucosal colonic explants and in a rabbit model of shigellosis. CONCLUSION: These results highlight a major protective function of EGCs and GSNO in the IEB against S flexneri attack. Consequently, this study lays the scientific basis for using GSNO to reduce barrier susceptibility to infectious or inflammatory challenge.

The multi-herbal drug STW 5 (Iberogast) has prosecretory action in the human intestine.

There is growing evidence that STW 5 (Iberogast), fixed combination of hydroethanolic herbal extracts), besides being effective in functional dyspepsia, also improves symptoms in irritable bowel syndrome (IBS). Clinical data indicate that modulation of mucosal secretion is a promising approach to treat intestinal disorders associated with IBS. We therefore explored the effect of STW 5 on secretion in the human intestine and the mechanisms by which it acts. The Ussing chamber technique was used to measure mucosal secretion in human intestinal mucosa/submucosa preparations and in human epithelial cell line T84. In addition, we recorded STW 5 effects on human enteric neurons with voltage sensitive dye imaging. In human tissue and T84 cells STW 5 induced a dose-dependent increase in ion secretion that was significantly reduced by the Na-K-Cl cotransporter blocker bumetanide, the adenylate cyclase inhibitor MDL-12 330, the non-specific and selective cystic fibrosis transmembrane conductance regulator (CFTR) inhibitors glibenclamide and CFTR(inh)-172, respectively, and the blocker of calcium dependent Cl(-) channels (ClCa) SITS (4-acetamido-4-isothiocyanatostilbene-2,2-disulphonic acid). It was unaffected by amiloride, a blocker of epithelial Na(+) channels. In human tissue, the nerve blocker tetrodotoxin significantly suppressed the STW 5 response. STW 5 evoked an increased spike discharge in 51% of human submucous neurons. Results suggest that STW 5 is a secretogogue in the human intestine by direct epithelial actions and through activation of enteric neurons. The prosecretory effect is due to increased epithelial Cl(-) fluxes via CFTR and Ca-dependent ClCa channels. STW 5 may be a novel option to treat secretory disorders associated with IBS and constipation.

Review article: the psychoneuroimmunology of irritable bowel syndrome--an exploration of interactions between psychological, neurological and immunological observations.

BACKGROUND: The pathogenesis of irritable bowel syndrome (IBS) is founded on interactive mechanisms. Disentangling these processes is a prerequisite for the development of effective drug therapy. AIM: To identify the interaction between the various factors implicated in IBS. METHODS: Articles pertaining to IBS pathogenesis focusing on psychoneuroimmunology were identified using following search terms: IBS, animal models, microbiota, probiotics, immunology, visceral hypersensitivity, imaging, psychology and visceral pain. RESULTS: Cerebral imaging using MRI and proton emission tomography scanning has revealed differential regional cerebral activation, whereas stimuli induced activation has been captured by both MRI and cortical evoked potentials. At the peripheral neurological level, the concept of visceral hypersensitivity has been challenged as perhaps representing psychological traits with symptom over-reporting or hyper-vigilance. Gut mucosal immunology is thought to be relevant with immunological changes reflected as peripheral blood cytokine level changes. Molecular technology advances suggest a role for microbiota by activating the gut immunological system. These interactions have been examined in IBS animal models. CONCLUSIONS: Translation of animal model findings to humans is needed to link the various psychological, neurological and immunological changes noted in IBS. This analysis may identify patient sub-groups, which will ultimately be critical for drug testing to be focused accordingly.

Diabetic rats supplemented with L-glutamine: a study of immunoreactive myosin-V myenteric neurons and the proximal colonic mucosa.

We studied the neuronal density and size of myenteric neurons and the epithelial cell proliferation and crypt depth of the proximal colon in diabetic Wistar rats after supplementing them with L-glutamine (1%). The animals were divided into five groups: untreated normoglycemic (UN), L-glutamine-treated normoglycemic (NG), untreated diabetic (UD), and L-glutamine-treated diabetics 4 days (DG4) and 45 days (DG45) days after the onset of diabetes. We observed a reduction of 52.7% and 50.44% in the neuronal density of the proximal colon of the UD group compared to the UN and NG groups, respectively (P<0.05). The neuronal density found for the DG4 (32.8%) and DG45 (28.6%) groups was higher than that of the UD group (P>0.05). There were no significant differences (P>0.05) when the data relative to the area of the myenteric neuron cell bodies, metaphasic index, and crypt depth in the proximal colon were compared among experimental groups.

Zinc attenuates forskolin-stimulated electrolyte secretion without involvement of the enteric nervous system in small intestinal epithelium from weaned piglets.

In a previous study, we found that secretagogue-stimulated electrolyte secretion was attenuated by dietary and serosal zinc in piglet small intestinal epithelium in Ussing chambers. Several studies show that the enteric nervous system (ENS) is involved in regulation of electrolyte and/or fluid transport in intestinal epithelium from many species. The aim of the present study is to examine the mechanisms behind the attenuating effect of zinc on electrolyte secretion and to study whether the ENS is involved in this effect of zinc in vitro. Twenty-four piglets (six litters of four piglets) were allocated randomly to one of two dietary treatments consisting of a basic diet supplemented with 100 mg zinc/kg (Zn(100)) or 2500 mg zinc/kg (Zn(2500)), as ZnO. All the piglets were killed at 5-6 days after weaning and in vitro experiments with small intestinal epithelium in Ussing chambers were carried out. Furthermore, zinc, copper, alkaline phosphatase (AP) and metallothionein (MT) in mucosa, liver, and plasma were measured. These measurements showed that zinc status was increased in the Zn(2500) compared to the Zn(100) fed piglets. The in vitro studies did not confirm previous findings of attenuating effects of dietary zinc and zinc in vitro on the 5-HT induced secretion. But it showed that the addition of zinc at the serosal side attenuated the forskolin (FSK) (cAMP-dependent) induced ion secretion in epithelium from piglets fed with Zn(100) diet. Blocking the ENS with lidocaine or hexamethonium apparently slightly reduced this effect of zinc in vitro, but did not remove the effect of zinc. Consequently, it is suggested that zinc attenuates the cAMP dependent ion secretion mainly due to an effect on epithelial cells rather than affecting the mucosal neuronal pathway.

Apoptosis in rat jejunal mucosa is regulated partly through the central nervous system, which controls feeding behavior.

AIM: The aim of this study was to investigate whether central nervous system-related feeding behavior regulates mucosal apoptosis in rat small intestines. METHODS: The test solutions used in this study were an H(1) receptor antagonist (chlorpheniramine maleate), 2-deoxy-D-glucose, leptin, and 1-deoxy-D-glucosamine (2-amino-1,5-anhydro-2-deoxy-D-glucitol). Test solutions were injected into the third cerebroventricles of rats. Feeding behavior and jejunal apoptosis were evaluated both with and without truncal vagotomy. Intestinal apoptosis was evaluated by percentage fragmented DNA, electrophoresis, and TUNEL staining. RESULTS: Chlorpheniramine and 2-deoxy-D-glucose elicited feeding, whereas leptin and 1-deoxy-D-glucosamine suppressed feeding. The test solutions, which elicited feeding (0.24 and 24 micromol/rat of chlorpheniramine and 2-deoxy-D-glucose, respectively), suppressed mucosal apoptosis in the rat jejunum 1 h after cerebroventricular infusion. In contrast, the test solutions, which suppressed feeding (8 and 24 micromol/rat of leptin and 1-deoxy-D-glucosamine, respectively), induced jejunal mucosal apoptosis 3 h after infusion. The effects of the test solutions on feeding behavior and changes in apoptosis were not affected by truncal vagotomy. CONCLUSION: The central nervous system, which regulates feeding behavior, might control intestinal function through the regulation of intestinal apoptosis.

Pathology of chronic constipation in pediatric and adult coloproctology.

In colonic motility disorders, a pathohistological diagnosis based solely on formalin-fixed gut is often inconclusive. Classical histological techniques or immunohistochemistry represent a static staining. In contrast, native tissue submitted to enzyme histochemistry provides functional information about the effectiveness of the cellular performance. Routinely, a complementary set of reactions is performed and includes acetylcholinesterase (AChE), lactic and succinic dehydrogenase, as well as nitroxide synthase reactions. In this monograph, the whole spectrum of different anomalies of the colonic wall is illustrated in a systematic fashion: Hirschsprung's disease is characterized by an increase in AChE activity of parasympathetic nerve fibers of the rectosigmoid. In ultrashort Hirschsprung's disease, only enzyme histochemistry renders a reliable diagnosis possible in biopsies of the anal ring. Aganglionosis of the musculus corrugator cutis ani shows a localized increase of AChE activity in nerve fibers, similar to Hirschsprung's disease, not detectable in conventional histology. Immaturity, hypoganglionosis and neuronal dysganglionosis can be clearly recognized in dehydrogenase reactions. Enzyme histochemical reactions are complemented by picrosirius red staining for assessment of the collagen texture of the muscularis propria. Absence or intertenial interruption of the continuous connective tissue layer between circular and longitudinal muscle of the muscularis propria has been termed aplastic or atrophic desmosis, respectively. Many of the entities described are also observed in adults. Atrophic hypoganglionosis or atrophic desmosis with loss of the myenteric plexus connective tissue fascia is implied as a frequent cause of chronic constipation in adults. The essential contribution of a functional histopathological technique towards a reliable diagnosis of gut dysfunction in native tissue is extensively demonstrated in great detail in more than two hundred figures.

Barakol extracted from Cassia siamea stimulates chloride secretion in rat colon.

Barakol is a purified extract of Cassia siamea, a plant that has been used as a laxative in traditional medicine. In this study, the effect of barakol on anion transport across the rat colon epithelium was investigated. Colonic epithelium was mounted in Ussing chambers and bathed with Ringer's solution. Addition of 1 mM barakol to the basolateral solution produced a slow increase in short-circuit current (Isc) in proximal colon and distal colon by 24.5 +/- 2.2 and 24.2 +/- 1.4 microA/cm(2), respectively. Barakol increased Isc in a concentration-dependent manner with an EC(50) value of 0.4 mM. The barakol-stimulated increase in Isc was inhibited by subsequent treatment with 500 microM diphenylamine-2-carboxylic acid or 400 microM glibenclamide added to the apical solution and 200 microM bumetanide added to the basolateral solution. Pretreatment of the tissues with 200 microM bumetanide, but not 10 microM amiloride, completely abolished the barakol-increased Isc. Ion substitution experiments showed an inhibition of barakol-stimulated Isc in chloride-free solution but not in bicarbonate-free solution. In addition, pretreatment of tissues with 10 microM tetrodotoxin or 10 microM indomethacin, but not 1 microM atropine or 10 microM hexamethonium, partially inhibited the Isc response by barakol. The present results demonstrated the stimulatory effect of barakol on the bumetanide-sensitive chloride secretion in rat colon. The effect of barakol was partly mediated by the stimulation of submucosal nerves and through the release of cyclooxygenase metabolites. These findings thus provide an explanation for the underlying mechanism of barakol as a secretagogue in mammalian colon.

Treatment of type 2 diabetes mellitus with agonists of the GLP-1 receptor or DPP-IV inhibitors.

Glucagon-like peptide-1 (GLP-1) is a peptide hormone from the gut that stimulates insulin secretion and protects beta-cells, inhibits glucagon secretion and gastric emptying, and reduces appetite and food intake. In agreement with these actions, it has been shown to be highly effective in the treatment of Type 2 diabetes, causing marked improvements in glycaemic profile, insulin sensitivity and beta-cell performance, as well as weight reduction. The hormone is metabolised rapidly by the enzyme dipeptidyl peptidase IV (DPP-IV) and, therefore, cannot be easily used clinically. Instead, resistant analogues of the hormone (or agonists of the GLP-1 receptor) are in development, along with DPP-IV inhibitors, which have been demonstrated to protect the endogenous hormone and enhance its activity. Agonists include both albumin-bound analogues of GLP-1 and exendin-4, a lizard peptide. Clinical studies with exendin have been carried out for > 6 months and have indicated efficacy in patients inadequately treated with oral antidiabetic agents. Orally active DPP-IV inhibitors, suitable for once-daily administration, have demonstrated similar efficacy. Diabetes therapy, based on GLP-1 receptor activation, therefore, appears very promising.

Effect of capsaicin on ion transport in the caecum of rabbits.

Effect of capsaicin, a stimulator of C-fibres, on ion transport in the caecum of rabbits was studied using electrophysiological methods, designed to evaluate ionic currents occurring in epithelial tissues. The experiments consisted in measuring transepithelial electrical potential difference (dPD) of an isolated fragment of rabbit's caecum, placed in a Ussing apparatus. The ion transport was modified through incubation in Ringer solution, supplemented with amiloride, bumetanide, and capsaicin. Capsaicin was also administered with peristalting pump. The experiments demonstrated that the inhibition of sodium ions transport caused by incubation with amiloride and incubation with capsaicin slowed down mechanical reaction to electrical potential difference. On the other hand, immediately after the administration, the capsaicin effect on C-fibres modified electrophysiological reaction of the caecum to mechanical stimulation. Physiological and pharmacological experiments reveal that a component dependent on activation of C-fibres contributes to the reaction of ion transport activation following mechanical stimulation.

Effect of the central nervous system on mucosal growth and apoptosis in the small intestine.

Recently our studies have demonstrated that the central nervous system regulates in part mucosal cell growth and apoptosis in the rat small intestine. Ornithine decarboxylase (ODC) activity is a key enzyme for polyamine synthesis which plays an important role for the intestinal mucosal growth. We have demonstrated that the increase of ODC activity in the duodenum just before the dark period is abolished by truncal vagotomy and that the infusion of 2-deoxy-D-glucose into the third cerebroventricle activates ODC activity in the small intestine. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. Our preliminary data showed that intestinal mucosal apoptosis decreased in the ventromedial-hypothalamus-lesioned rat. These results indicate that the central nervous system, in addition to local factors, is related to regulation of mucosal homeostasis in the intestinal mucosa.