Mouse Large Intestine Research Articles

Anoctamins support calcium-dependent chloride secretion by facilitating calcium signaling in adult mouse intestine

Intestinal epithelial electrolyte secretion is activated by increase in intracellular cAMP or Ca(2+) and opening of apical Cl(-) channels. In infants and young animals, but not in adults, Ca(2+)-activated chloride channels may cause secretory diarrhea during rotavirus infection. While detailed knowledge exists concerning the contribution of cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR) channels, analysis of the role of Ca(2+)-dependent Cl(-) channels became possible through identification of the anoctamin (TMEM16) family of proteins. We demonstrate expression of several anoctamin paralogues in mouse small and large intestines. Using intestinal-specific mouse knockout models for anoctamin 1 (Ano1) and anoctamin 10 (Ano10) and a conventional knockout model for anoctamin 6 (Ano6), we demonstrate the role of anoctamins for Ca(2+)-dependent Cl(-) secretion induced by the muscarinic agonist carbachol (CCH). Ano1 is preferentially expressed in the ileum and large intestine, where it supports Ca(2+)-activated Cl(-) secretion. In contrast, Ano10 is essential for Ca(2+)-dependent Cl(-) secretion in jejunum, where expression of Ano1 was not detected. Although broadly expressed, Ano6 has no role in intestinal cholinergic Cl(-) secretion. Ano1 is located in a basolateral compartment/membrane rather than in the apical membrane, where it supports CCH-induced Ca(2+) increase, while the essential and possibly only apical Cl(-) channel is CFTR. These results define a new role of Ano1 for intestinal Ca(2+)-dependent Cl(-) secretion and demonstrate for the first time a contribution of Ano10 to intestinal transport.

Comprehensive characterization of protein 4.1 expression in epithelium of large intestine.

The protein 4.1 family consists of four members, 4.1R, 4.1N, 4.1B and 4.1G, each encoded by a distinct gene. All 4.1 mRNAs undergo extensive alternative splicing. Functionally, they usually serve as adapters that link actin-based cytoskeleton to plasma membrane proteins. It has been reported that 4.1 proteins are expressed in most animal cell types and tissues including epithelial cells and epithelial tissues. However, the expression of 4.1 proteins in large intestine has not been well characterized. In the present study, we performed RT-PCR, western blot and immunohistochemistry analysis to characterize the transcripts, the protein expression and cellular localization of 4.1 proteins in the epithelia of mouse large intestine. We show that multiple transcripts derive from each gene, including eight 4.1R isoforms, four 4.1N isoforms, four 4.1B isoforms and six 4.1G isoforms. However, at the protein level, only one or two major bands were detected, implying that not all transcripts are translated and/or the proteins do not accumulate at detectable levels. Immunohistochemistry revealed that 4.1R, 4.1N and 4.1B are all expressed at the lateral membrane as well as cytoplasm of epithelial cells, suggesting a potentially redundant role of these proteins. Our findings not only provide new insights into the structure of protein 4.1 genes but also lay the foundation for future functional studies.

Expressions of tight junction proteins Occludin and Claudin-1 are under the circadian control in the mouse large intestine: implications in intestinal permeability and susceptibility to colitis.

Background & AimsThe circadian clock drives daily rhythms in behavior and physiology. A recent study suggests that intestinal permeability is also under control of the circadian clock. However, the precise mechanisms remain largely unknown. Because intestinal permeability depends on tight junction (TJ) that regulates the epithelial paracellular pathway, this study investigated whether the circadian clock regulates the expression levels of TJ proteins in the intestine.MethodsThe expression levels of TJ proteins in the large intestinal epithelium and colonic permeability were analyzed every 4, 6, or 12 hours between wild-type mice and mice with a mutation of a key clock gene Period2 (Per2; mPer2m/m). In addition, the susceptibility to dextran sodium sulfate (DSS)-induced colitis was compared between wild-type mice and mPer2m/m mice.ResultsThe mRNA and protein expression levels of Occludin and Claudin-1 exhibited daily variations in the colonic epithelium in wild-type mice, whereas they were constitutively high in mPer2m/m mice. Colonic permeability in wild-type mice exhibited daily variations, which was inversely associated with the expression levels of Occludin and Claudin-1 proteins, whereas it was constitutively low in mPer2m/m mice. mPer2m/m mice were more resistant to the colonic injury induced by DSS than wild-type mice.ConclusionsOccludin and Claudin-1 expressions in the large intestine are under the circadian control, which is associated with temporal regulation of colonic permeability and also susceptibility to colitis.

Exhaustive exercise increases the TNF-α production in response to flagellin via the upregulation of toll-like receptor 5 in the large intestine in mice

Although intense exercise may induce temporary immune depression, it is unclear whether exercise stimulates tumor necrosis factor-alpha (TNF-α) production in response to flagella protein flagellin (FG), which binds to toll-like receptor 5 (TLR5) and induces the production of pro-inflammatory cytokines. Male C3H/HeN mice were administered FG (1mg/kg, i.v.) after exhaustive exercise (EX), and the plasma TNF-α concentrations were examined. The production of TNF-α and the TLR5 expression in both RAW264 and Caco2 cells were measured under FG conditions in vitro. Although the plasma TNF-α concentrations were observed to significantly increase in both the EX and non-EX (N-EX) mice (p<0.01, respectively) following FG injection, the TNF-α levels in the EX mice were significantly higher than those observed in the N-EX mice (p<0.01). Epinephrine (Ep) treatment accelerated the FG-induced TNF-α production and TLR5 expression on the Caco2, but not RAW264 cells. Interestingly, a high Ep-induced TLR5 expression was observed on the Caco2 cell surface, which was inhibited by an inhibitor of phosphoinositide3-kinase (PI3K), Ly294002, as well as a β-adrenergic blocker, propranolol. In addition, the EX-induced TNF-α production observed in response to FG was also attenuated by pretreatment with propranolol. Our findings suggest that exhaustive exercise upregulates the production of TNF-α in response to FG via a high expression of TLR5 on the intestinal cell surface following the stimulation of β-adrenergic receptors with exercise.

Novel diet-related mouse model of colon cancer parallels human colon cancer.

To investigate the close parallels between our novel diet-related mouse model of colon cancer and human colon cancer. Twenty-two wild-type female mice (ages 6-8 wk) were fed the standard control diet (AIN-93G) and an additional 22 female mice (ages 6-8 wk) were fed the control diet supplemented with 0.2% deoxycholic acid [diet + deoxycholic acid (DOC)] for 10 mo. Tumors occurred in the colons of mice fed diet + DOC and showed progression to colon cancer [adenocarcinoma (AC)]. This progression is through the stages of tubular adenoma (TA), TA with high grade dysplasia or adenoma with sessile serrated morphology, intramucosal AC, AC stage T1, and AC stage T2. The mouse tumors were compared to human tumors at the same stages by histopathological analysis. Sections of the small and large intestines of mice and humans were evaluated for glandular architecture, cellular and nuclear morphology including cellular orientation, cellular and nuclear atypia, pleomorphism, mitotic activity, frequency of goblet cells, crypt architecture, ulceration, penetration of crypts through the muscularis mucosa and presence of malignant crypts in the muscularis propria. In addition, preserved colonic tissues from genetically similar male mice, obtained from a prior experiment, were analyzed by immunohistochemistry. The male mice had been fed the control diet or diet + DOC. Four molecular markers were evaluated: 8-OH-dG, DNA repair protein ERCC1, autophagy protein beclin-1 and the nuclear location of beta-catenin in the stem cell region of crypts. Also, male mice fed diet + DOC plus 0.007% chlorogenic acid (diet + DOC + CGA) were evaluated for ERCC1, beclin-1 and nuclear location of beta-catenin. Humans with high levels of diet-related DOC in their colons are at a substantially increased risk of developing colon cancer. The mice fed diet + DOC had levels of DOC in their colons comparable to that of humans on a high fat diet. The 22 mice without added DOC in their diet had no colonic tumors while 20 of the 22 mice (91%) fed diet + DOC developed colonic tumors. Furthermore, the tumors in 10 of these mice (45% of mice) included an adenocarcinoma. All mice were free of cancers of the small intestine. Histopathologically, the colonic tumor types in the mice were virtually identical to those in humans. In humans, characteristic aberrant changes in molecular markers can be detected both in field defects surrounding cancers (from which cancers arise) and within cancers. In the colonic tissues of mice fed diet + DOC similar changes in biomarkers appeared to occur. Thus, 8-OH-dG was increased, DNA repair protein ERCC1 was decreased, autophagy protein beclin-1 was increased and, in the stem cell region at the base of crypts there was substantial nuclear localization of beta-catenin as well as increased cytoplasmic beta-catenin. However, in mice fed diet + DOC + CGA (with reduced frequency of cancer) and evaluated for ERCC1, beclin-1, and beta-catenin in the stem cell region of crypts, mouse tissue showed amelioration of the aberrancies, suggesting that chlorogenic acid is protective at the molecular level against colon cancer. This is the first diet-related model of colon cancer that closely parallels human progression to colon cancer, both at the histomorphological level as well as in its molecular profile. The diet-related mouse model of colon cancer parallels progression to colon cancer in humans, and should be uniquely useful in model studies of prevention and therapeutics.

A novel anterograde neuronal tracing technique to selectively label spinal afferent nerve endings that encode noxious and innocuous stimuli in visceral organs

One major weakness in our understanding of pain perception from visceral organs is the lack of knowledge of the location, morphology and neurochemistry of all the different types of spinal afferent nerve endings, which detect noxious and innocuous stimuli. This is because we lack techniques to selectively label only spinal afferents. Our aim was to develop an anterograde tracing technique that labels only spinal afferent nerve endings in visceral organs, without also labeling all other classes of extrinsic afferent and efferent nerves. Mice were anesthetized with isoflurane and dextran-biotin injected, via glass micropipettes (diameter 5 μm), into L6 and S1 dorsal root ganglia. Mice recovered for 7 days, were then euthanized and the colon removed. Anterograde labeling revealed multiple unique classes of afferent endings that terminated within distinct anatomical layers of the colon and rectum. We characterized a particular class of intramuscular ending in the circular muscle (CM) layer of the colon that consists of multiple varicose axons that project circumferentially. We demonstrate a technique for selective anterograde labeling of spinal afferent nerve endings in visceral organs. This approach facilitates selective visualization of the precise morphology and location of the different classes of spinal afferent endings, without visual interference caused by indiscriminant labeling of other classes of afferent and efferent nerve axons which also innervate internal organs. We have used this new technique to identify and describe the details of a particular class of intramuscular spinal afferent ending in the CM layer of mouse large intestine.

The Retinoic Acid Receptor Agonist Am80 Increases Mucosal Inflammation in an IL-6 Dependent Manner During Trichuris muris Infection

PurposeVitamin A metabolites, such as all-trans-retinoic acid (RA) that act through the nuclear receptor; retinoic acid receptor (RAR), have been shown to polarise T cells towards Th2, and to be important in resistance to helminth infections. Co-incidentally, people harbouring intestinal parasites are often supplemented with vitamin A, as both vitamin A deficiency and parasite infections often occur in the same regions of the globe. However, the impact of vitamin A supplementation on gut inflammation caused by intestinal parasites is not yet completely understood.MethodsHere, we use Trichuris muris, a helminth parasite that buries into the large intestine of mice causing mucosal inflammation, as a model of both human Trichuriasis and IBD, treat with an RARα/β agonist (Am80) and quantify the ensuing pathological changes in the gut.ResultsCritically, we show, for the first time, that rather than playing an anti-inflammatory role, Am80 actually exacerbates helminth-driven inflammation, demonstrated by an increased colonic crypt length and a significant CD4+ T cell infiltrate. Further, we established that the Am80-driven crypt hyperplasia and CD4+ T cell infiltrate were dependent on IL-6, as both were absent in Am80-treated IL-6 knock-out mice.ConclusionsThis study presents novel data showing a pro-inflammatory role of RAR ligands in T. muris infection, and implies an undesirable effect for the administration of vitamin A during chronic helminth infection.Electronic supplementary materialThe online version of this article (doi:10.1007/s10875-013-9936-8) contains supplementary material, which is available to authorized users.

Transcellular oxalate and Cl−absorption in mouse intestine is mediated by the DRA anion exchanger Slc26a3, and DRA deletion decreases urinary oxalate

Active transcellular oxalate transport in the mammalian intestine contributes to the homeostasis of this important lithogenic anion. Several members of the Slc26a gene family of anion exchangers have a measurable oxalate affinity and are expressed along the gut, apically and basolaterally. Mouse Slc26a6 (PAT1) targets to the apical membrane of enterocytes in the small intestine, and its deletion results in net oxalate absorption and hyperoxaluria. Apical exchangers of the Slc26a family that mediate oxalate absorption have not been established, yet the Slc26a3 [downregulated in adenoma (DRA)] protein is a candidate mediator of oxalate uptake. We evaluated the role of DRA in intestinal oxalate and Cl(-) transport by comparing unidirectional and net ion fluxes across short-circuited segments of small (ileum) and large (cecum and distal colon) intestine from wild-type (WT) and DRA knockout (KO) mice. In WT mice, all segments demonstrated net oxalate and Cl(-) absorption to varying degrees. In KO mice, however, all segments exhibited net anion secretion, which was consistently, and solely, due to a significant reduction in the absorptive unidirectional fluxes. In KO mice, daily urinary oxalate excretion was reduced 66% compared with that in WT mice, while urinary creatinine excretion was unchanged. We conclude that DRA mediates a predominance of the apical uptake of oxalate and Cl(-) absorbed in the small and large intestine of mice under short-circuit conditions. The large reductions in urinary oxalate excretion underscore the importance of transcellular intestinal oxalate absorption, in general, and, more specifically, the importance of the DRA exchanger in oxalate homeostasis.

Euphorbia kansui roots induced-diarrhea in mice correlates with inflammatory response

AimEuphorbia kansui (E. KS) is a traditional medicine used in China for thousands of years with the effect of propulsion in the gastrointestines. However, there is no reported study of E. KS on gastrointestinal motility until now. The aim of this work is to study the effect of E. KS on the propulsion of gastrointestines, and to elucidate the possible mechanism of action. MethodsE.KS was prepared as a 30% ethanol extract and used for the experiment of small and large intestines of mice by oral administration with three different dosages (1.2, 0.6 and 0.3 g·kg−1). The feces were observed in vivo. The morphology was carried out to detect if there are any changes in the intestines after the extract of E. KS administration. The assays of mRNA and protein expression were employed to observe IL-1β, TNFα and caspase 3. ResultsIt was shown that the extract of E.KS promoted diarrhea in mouse feces after administration, inhibited the contraction of smooth muscle of mouse small intestine and caused the inflammatory exudation on the mucosa of the intestines, enhanced the expression of both mRNA and the protein levels of IL-1β and TNFα in the small or large intestines. ConclusionThe results showed that the extract of E. KS acted on the intestinal smooth muscle with propulsion of feces involving the irritation of the intestines with acute inflammatory reactions.

Abstract LB-52: Increased incidence of cancer in the transgenic mice with 8-Lipoxygenase knocked out.

Abstract 15-Lipoxygenase-2 (ALOX15B), an oxidoreductase in the metabolism of arachidonic acid, is a functional tumor suppressor whose expression is reduced in a variety of human cancers. To determine the roles of ALOX15B in carcinogenesis, we generated transgenic mice with ALOX8, the murine homolog of ALOX15B, knocked out. ALOX8 expression at mRNA level was abolished in homozygous knockout mice and reduced to half of wild type in heterozygous knockout mice. It's observed that homozygous female ALOX8 knockout mice are infertile but male ALOX8 knockout mice are fertile. Increased incidence of tumor as uni or multimass was found in the lung, prostate and in the mesentery region of homozygous and heterozygous ALOX8 knockout mice, when compared with little mate wild type mice. Histological evaluations showed an increase in secondary tumors and inflammation in different tissues like lung and large intestine in mice with ALOX8 knocked out. The transgenic mice could be a good model to study the role of 8-lipoxygenase in carcinogenesis and may provide insights into the tumor suppressing activities of human ALOX15B. Citation Format: Rana Al-Fardan, Rabindra Karki, Changxiong Guo, Daotai Nie. Increased incidence of cancer in the transgenic mice with 8-Lipoxygenase knocked out. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-52. doi:10.1158/1538-7445.AM2013-LB-52

Clear evidence of carcinogenic activity by a whole-leaf extract of Aloe barbadensis miller (aloe vera) in F344/N rats.

Aloe barbadensis Miller (Aloe vera) is an herbal remedy promoted to treat a variety of illnesses; however, only limited data are available on the safety of this dietary supplement. Drinking water exposure of F344/N rats and B6C3F1 mice to an Aloe vera whole-leaf extract (1, 2, and 3%) for 13 weeks resulted in goblet cell hyperplasia of the large intestine in both species. Based upon this observation, 2-year drinking water studies were conducted to assess the carcinogenic potential of an Aloe vera whole-leaf extract when administered to F344/N rats (48 per sex per group) at 0.5, 1, and 1.5%, and B6C3F1 mice (48 per sex per group) at 1, 2, and 3%. Compared with controls, survival was decreased in the 1.5% dose group of female rats. Treatment-related neoplasms and nonneoplastic lesions in both species were confined primarily to the large intestine. Incidences of adenomas and/or carcinomas of the ileo-cecal and cecal-colic junction, cecum, and ascending and transverse colon were significantly higher than controls in male and female rats in the 1 and 1.5% dose groups. There were no neoplasms of the large intestine in mice or in the 0 or 0.5% dose groups of rats. Increased incidences of mucosa hyperplasia of the large intestine were observed in F344/N rats, and increased incidences of goblet cell hyperplasia of the large intestine occurred in B6C3F1 mice. These results indicate that Aloe vera whole-leaf extract is an intestinal irritant in F344/N rats and B6C3F1 mice and a carcinogen of the large intestine in F344/N rats.

Mechanosensitive Enteric Neurons in the Myenteric Plexus of the Mouse Intestine

BackgroundWithin the gut the autonomous enteric nervous system (ENS) is able to sense mechanical stimuli and to trigger gut reflex behaviour. We previously proposed a novel sensory circuit in the ENS which consists of multifunctional rapidly adapting mechanosensitive enteric neurons (RAMEN) in the guinea pig. The aim of this study was to validate this concept by studying its applicability to other species or gut regions.Methodology/Principal FindingsWe deformed myenteric ganglia in the mouse small and large intestine and recorded spike discharge using voltage sensitive dye imaging. We also analysed expression of markers hitherto proposed to label mouse sensory myenteric neurons in the ileum (NF145kD) or colon (calretinin). RAMEN constituted 22% and 15% of myenteric neurons per ganglion in the ileum and colon, respectively. They encoded dynamic rather than sustained deformation. In the colon, 7% of mechanosensitive neurons fired throughout the sustained deformation, a behaviour typical for slowly adapting echanosensitive neurons (SAMEN). RAMEN and SAMEN responded directly to mechanical deformation as their response remained unchanged after synaptic blockade in low Ca++/high Mg++. Activity levels of RAMEN increased with the degree of ganglion deformation. Recruitment of more RAMEN with stronger stimuli may suggest low and high threshold RAMEN. The majority of RAMEN were cholinergic but most lacked expression of NF145kD or calretinin.Conclusions/SignificanceWe showed for the first time that fundamental properties of mechanosensitive enteric neurons, such as firing pattern, encoding of dynamic deformation, cholinergic phenotype and their proportion, are conserved across species and regions. We conclude that RAMEN are important for mechanotransduction in the ENS. They directly encode dynamic changes in force as their firing frequency is proportional to the degree of deformation of the ganglion they reside in. The additional existence of SAMEN in the colon is likely an adaptation to colonic motor patterns which consist of phasic and tonic contractions.

Lack of thrombospondin‐1 increases tumorigenesis and decreases survival of in a new mouse model of colorectal cancer

According to the National Cancer Institute more than 140,000 people will be diagnosed in the United States with colorectal cancer this year alone. The adenomatus polyposis coli (APC) gene is frequently mutated in colorectal cancer, the APC‐min mouse correspondingly is a widely used model for the study of this type of cancer. Yet, intestinal tumors develop predominately in the small intestine reflecting familial adenomatous polyposis rather than colorectal cancer. Studies indicate that the matricellular protein Thrombospondin 1 (TSP1), a key component in modifying inflammatory processes, is lost during the development of colon cancer. To study the role of TSP1 during inflammation driven colorectal carcinogenesis we developed an APC‐min and TSP−/− APC‐min mouse model. A lack of TSP1 increases tumor size and multiplicity predominately in the large intestine of these mice. Our data indicate that expression of TSP1 in the APC‐min mouse prevents the development of adenomas in the large intestine in mice fed a low fat diet. Moreover, TSP−/− APC‐min mice show 50% reduction in survival when compared to TSP+/+APC‐min mice alone (P&lt;0.05). Our in vitro experiments indicate that this difference may be due to TSP1 regulation of pro‐inflammatory mechanisms. Together this data indicates TSP1 regulates progression of colon carcinogenesis and define cellular and molecular targets of TSP1 in the prevention of colorectal cancer.

An ex vivo method for studying mucus formation, properties, and thickness in human colonic biopsies and mouse small and large intestinal explants

The colon mucus layers minimize the contact between the luminal flora and the epithelial cells, and defects in this barrier may lead to colonic inflammation. We now describe an ex vivo method for analysis of mucus properties in human colon and mouse small and large intestine. Intestinal explants were mounted in horizontal perfusion chambers. The mucus surface was visualized by adding charcoal particles on the apical side, and mucus thickness was measured using a micropipette. Mucus thickness, adhesion, and growth rate were recorded for 1 h. In mouse and human colon, the ability of the mucus to act as a barrier to beads the size of bacteria was also evaluated. Tissue viability was monitored by transepithelial potential difference. In mouse ileum, the mucus could be removed by gentle aspiration, whereas in colon ∼40 μm of the mucus remained attached to the epithelial surface. Both mouse and human colon had an inner mucus layer that was not penetrated by the fluorescent beads. Spontaneous mucus growth was observed in human (240 μm/h) and mouse (100 μm/h) colon but not in mouse ileum. In contrast, stimulation with carbachol induced a higher mucus secretion in ileum than colon (mouse ileum: Δ200 μm, mouse colon: Δ130 μm, human colon: Δ140 μm). In conclusion, while retaining key properties from the mucus system in vivo, this setup also allows for studies of the highly dynamic mucus system under well-controlled conditions.

Anaerobic Respiration of Escherichia coli in the Mouse Intestine

The intestine is inhabited by a large microbial community consisting primarily of anaerobes and, to a lesser extent, facultative anaerobes, such as Escherichia coli, which we have shown requires aerobic respiration to compete successfully in the mouse intestine (S. A. Jones et al., Infect. Immun. 75:4891-4899, 2007). If facultative anaerobes efficiently lower oxygen availability in the intestine, then their sustained growth must also depend on anaerobic metabolism. In support of this idea, mutants lacking nitrate reductase or fumarate reductase have extreme colonization defects. Here, we further explore the role of anaerobic respiration in colonization using the streptomycin-treated mouse model. We found that respiratory electron flow is primarily via the naphthoquinones, which pass electrons to cytochrome bd oxidase and the anaerobic terminal reductases. We found that E. coli uses nitrate and fumarate in the intestine, but not nitrite, dimethyl sulfoxide, or trimethylamine N-oxide. Competitive colonizations revealed that cytochrome bd oxidase is more advantageous than nitrate reductase or fumarate reductase. Strains lacking nitrate reductase outcompeted fumarate reductase mutants once the nitrate concentration in cecal mucus reached submillimolar levels, indicating that fumarate is the more important anaerobic electron acceptor in the intestine because nitrate is limiting. Since nitrate is highest in the absence of E. coli, we conclude that E. coli is the only bacterium in the streptomycin-treated mouse large intestine that respires nitrate. Lastly, we demonstrated that a mutant lacking the NarXL regulator (activator of the NarG system), but not a mutant lacking the NarP-NarQ regulator, has a colonization defect, consistent with the advantage provided by NarG. The emerging picture is one in which gene regulation is tuned to balance expression of the terminal reductases that E. coli uses to maximize its competitiveness and achieve the highest possible population in the intestine.

Localization of Transient Receptor Potential Melastatin Type-8 (TRPM8) in Normal Mouse Large Intestine and Its Up-Regulation in Inflammatory Bowel Disease Model

colitis model mice, disease activity index, tissue inflammation and amount of 5-HT was gradually increased during 7 days of DSS treatment. The visceral hyperalgesia to mechanical distension was observed on day 7 but not on day 4. The number of 5-HT3 receptorexpressing nerve fibers is significantly increased in mucosa on day 7. On the other hand, number of the 5-HT4 receptor-expressing nerve fibers is significantly decreased on day 7. No significant alteration in the number of 5-HT3 and 5-HT4 receptors was detected on day 4. Progress of the inflammation led to down regulation of SERT immunoreactivities with concomitant increases in 5-HTand TPH-1-positive cell numbers. 5-HTand TPH-1-positive cells were widely distributed in whole mucosa on day 0 and 4. On day 7, these cells were mainly detected in upper part of mucosa. A significant 2-fold increase in number of TRPV1expressing nerve fibers was found inmucosa on day 7. Non-neuronal TRPV1-immunopositive cells were observed on day 7. There is no clear alteration of the immunoreactivities of the 5-HT signaling and the TRPV1 channels in muscle layers of rectum in colitis model mice. CONCLUSION: These results suggest that increased 5-HT, 5-HT3 receptors, TRPV1 channels and decreased 5-HT4 receptors are associated with the pathological conditions of the inflammatory bowel disease.

Metabolic activation of sennoside C in mice: synergistic action of anthrones.

Sennosides A and C directly injected into the caecum of mice showed equal purgative activity. Intracaecal administration reduced time to onset of diarrhoea induced by sennoside C from about 3 h after oral administration to about 24 min. At 2.3 h after oral administration of sennoside C, nearly equimolar amounts of aloe-emodin anthrone and rhein anthrone were detected in the large intestine of mice. The purgative effect of oral sennoside C could be reduced by pretreating mice with chloramphenicol. This was observed as a decreased formation of total anthrones in the large intestine. Both anthrones and an equimolar mixture of both anthrones directly injected into the caecum exerted a purgative effect, although the activity was lower for aloe-emodin anthrone. The intracaecal ED50 values were 54.5 (24.1-89.6), 11.4 (5.0-15.7) and 11.2 (6.1-14.6) mumol kg-1 for aloe-emodin anthrone, rhein anthrone and an equimolar mixture of both anthrones, respectively. We concluded that aloe-emodin anthrone and rhein anthrone, formed mainly by intraluminal bacterial action, are the true active metabolites of sennoside C in mice and that both anthrones synergistically exert their purgative effects on mice.

Synergic Effect of Trimebutine Combined with Mosapride on Gastrointestinal Dysfunction and Visceral Pain Induced in Stress Models

The present study was undertaken to determine whether combined treatment with prokinetic trimebutine and mosapride has a synergic effect on gastrointestinal motility and visceral pain associated with gastrointestinal dysfunction. To develop effective gastroprokinetic agents with greater potencies than trimebutine or mosapride for the treatment of gastrointestinal tract disease, a mixture of trimebutine and mosapride was designed and prepared. In the present study, treatment with trimebutine alone showed a dose-dependent effect on propelling movements of normal small and large intestine in mice, whereas mosapride effected only small intestine motility. Co-administration of trimebutine with mosapride, a well-established prokinetic drug, produced a synergistic infl uence on normal small intestine motility, but demonstrated an unclear effect on large intestine motility, with a slight tendency to reduce the propelling time. In a stress model, the small and large intestine motilities were signifi cantly decreased. The reduction of intestine motility was restored to a normal level and the restoring effect was more pronounced in the combined treatment with trimebutine plus mosapride than treatment with trimebutine or mosapride alone. Furthermore, treatment with trimebutine plus mosapride signifi cantly decreased acute visceral pain which was not controlled by trimebutine or mosapride alone. These data suggest that combination therapy with trimebutine plus mosapride has a synergic effect on small and large intestine motility and visceral pain control in gastrointestinal disorders.

Adhesion Activity ofLactobacillus plantarumPM 008 Isolated from Kimchi on the Intestine of Mice

Lactic acid bacteria (LAB), including L. plantarum isolated from Kimchi, are beneficial and safe microorganisms that improve disturbances of the indigenous microflora and the host's immune system. The adhesion abilities of Kimchi-derived L. plantarum PM008 and yogurt-derived L. casei were measured in vitro and in vivo. When L. plantarum or L. casei was incubated with Caco-2 cells, these Lactobacillus strains were potently attached. When these strains were orally administered to mice, the LABs were attached on the large intestine of mice. The attachment of L. plantarum on murine intestine or Caco-2 intestinal epithelial cell lines was more potent than that of L. casei, although numbers of LAB between their feces were not different. Treatment with either L. plantarum or L. casei for 14 days suppressed fecal β-glucuronidase activity, although treatment for one day did not affect it. L. plantarum showed more potent inhibition than L. casei. In addition, L. plantarum and L. casei were stable to artificial gastric and intestinal juice. L. plantarum was more stable than L. casei. Based on these findings, the survival and adhesion effects of orally administered LAB strains in the intestine may increase numbers of LAB in intestine and express their biological activities.

Immunolocalization of membrane skeletal protein, 4.1G, in enteric glial cells in the mouse large intestine

4.1 family proteins are membrane skeletal proteins that interact with spectrin–actin networks and intramembraneous proteins. We reported that one of them, 4.1G, was immunolocalized in myelinated nerve fibers of the mouse peripheral nervous system, especially along cell membranes of paranodes and Schmidt–Lanterman incisures in Schwann cells. In this study, to examine 4.1G's appearance in unmyelinated peripheral nerve fibers, we focused on the enteric nervous system in mouse large intestines. In intestinal tissues prepared by an “in vivo cryotechnique” followed by freeze-substitution fixation, 4.1G was immunolocalized in Auerbach's myenteric plexus and connecting nerve fiber networks. Its immunostaining was mostly colocalized with glial fibrillar acidic protein, a marker of enteric glial cells, but not with c-Kit, a marker of interstitial cells of Cajal. Using whole-mount preparation after splitting inner and outer muscle layers, the nerve fiber networks including the plexus were clearly detected by the 4.1G immunostaining. By conventional pre-embedding immunoelectron microscopy, 4.1G was detected along cell membranes of enteric glial cells and their processes surrounding axons. These indicate that 4.1G may have some roles in adhesion and/or signal transduction in unmylinated PNS nerve fibers.