The risk of gastrointestinal malignancies in cystic fibrosis: case report of a patient with a near obstructing villous adenoma found on colon cancer screening and Barrett's esophagus.

The life expectancy for cystic fibrosis (CF) patients has increased dramatically over the last 30 years. Although the overall cancer risk for CF patients does not appear to be increased there is a marked increased risk of gastrointestinal malignancies especially in the post lung transplant population. CF patients that do develop gastrointestinal malignancies do so at an earlier age and there is often a lag in the diagnosis and management of these individuals. We present a 39 year old male CF patient that underwent a colonoscopy for colon cancer screening and a large, near obstructing, villous adenoma of his ileum was found. The polyp was removed successfully via endoscopy without incident and there was no evidence of malignancy. An upper endoscopy revealed a long segment of Barrett's esophagus with no evidence of dysplasia. We present this case as well as a detailed review of the literature on cancer risk in CF and a discussion of the mechanisms that may be involved. We also present the risk of GI malignancies in non-CF patients as a guide on how to assess and manage the risk of GI malignancies in this ever-changing patient population.

Combined challenge of mice with Citrobacter rodentium and ionizing radiation promotes bacterial translocation.

PURPOSE: Both enteric infection and exposure to ionizing radiation are associated with increased intestinal permeability. However, the combined effect of irradiation and enteric infection has not been described. We combined infection of mice with the enteric pathogen, Citrobacter rodentium, with exposure to ionizing radiation and assessed the impact on colonic epithelial ion transport, permeability and bacterial translocation. MATERIALS AND METHODS: Mice were infected with C. rodentium and then received whole-body exposure to 5 Gray gamma-radiation 7 days later. Three days post-irradiation, mice were euthanized and colons removed. Control groups included sham-infected mice that were irradiated and mice that were infected, but not irradiated. RESULTS: Macroscopic damage score and colonic wall thickness were increased by C. rodentium infection, but these parameters were not exacerbated by irradiation. Infection caused an increase in myeloperoxidase activity that was reduced by irradiation. Irradiation reduced the secretory response to electrical field stimulation, forskolin and carbachol; these changes were not altered by infection with C. rodentium. None of the treatments caused an increase in permeability to 51Cr-ethylenediaminetetraacetic acid (EDTA). However, combined infection and irradiation synergistically increased bacterial translocation to mesenteric lymph nodes, liver, spleen and blood. CONCLUSIONS: Although the combination of irradiation and infection did not exacerbate the individual effects of these challenges on ion secretion and mucosal permeability to 51Cr-EDTA, it dramatically increased susceptibility to bacterial translocation and bacteremia. These results have important implications for patients who develop an enteric infection during the course of abdominopelvic radiotherapy.

Protection of rat gastric mucosa by sucralfate. Effects of luminal stasis and of inhibition of prostaglandins synthesis.

Studies using a gastric chamber model demonstrated that sucralfate protected the rat gastric mucosa against hemorrhagic erosions induced by 40 percent ethanol and by acidified 80 mM sodium taurocholate. Protection required continuous contact of sucralfate with the gastric mucosa but it occurred without the production, by sucralfate alone, of significant damage to the luminal epithelium. Ultrastructural examination indicated that sucralfate stimulated mucus secretion by surface epithelial cells. Furthermore, sucralfate was "cytoprotective" in that, in addition to its anti-ulcer effects, it significantly reduced the damaging effects of luminal ethanol on the surface epithelium. Luminal stasis also significantly reduced the extent of hemorrhagic erosions produced by both ethanol and sodium taurocholate, but the most effective reduction in erosions occurred when sucralfate and luminal stasis were combined. Pretreatment with indomethacin abolished the protection provided by luminal stasis, but this protection was restored by sucralfate. Thus, these studies suggest that protection of the gastric mucosa by sucralfate results in part from effects on the unstirred layer. Sucralfate or its products also interact with the epithelial cells and stimulate mucus release and synthesis or release of inflammatory mediators.

Review article: new insights into the pathogenesis of radiation-induced intestinal dysfunction.

Exposure of the abdomino-pelvic region to ionizing radiation, such as that received during radiotherapy, is associated with the development of a number of untoward symptoms which may limit the course of therapy or which may involve serious chronic intestinal disease. While the mucosal dysfunction surrounding acute radiation enteritis is generally ascribed to the effects of ionizing radiation on the cell cycle of epithelial stem cells of the intestinal crypts and subsequent epithelial loss, recent evidence suggests that other, earlier events also play a role. The severity of these early events may determine the incidence and severity of chronic enteritis. The mechanism for this is unclear, but may relate to radiation-induced compromise of host defence responses to luminal pathogens or antigens. This review will address the current state of knowledge of the pathogenesis of radiation-induced intestinal dysfunction, focusing on events which occur in the mucosa, and will discuss what the future may hold with respect to the treatment of radiation-associated diseases of the intestinal tract.

Aspirin causes rapid up-regulation of cyclo-oxygenase-2 expression in the stomach of rats.

BACKGROUND: Cyclo-oxygenase-1 (COX-1) is believed to produce prostaglandins vital to mucosal defence, whereas cyclo-oxygenase-2 (COX-2) is induced at sites of inflammation. Little is known about the regulation of COX-2 in the stomach, particularly during the period following mucosal injury. In this study, we examined COX-1 and COX-2 expression shortly after administration of NSAIDs or ethanol. METHODS: Fasted rats were given aspirin, salicylate, indomethacin or ethanol (20% or 40%) orally. Three hours later the stomach was excised, the severity of damage scored and samples taken for RT-PCR of COX-1 and COX-2 mRNA and immunohistochemistry. Nitric oxide synthase mRNA (iNOS and eNOS) and activity were also measured. RESULTS: Aspirin, indomethacin and the higher concentration of ethanol produced widespread mucosal damage, whereas salicylate and 20% ethanol caused only superficial epithelial damage. Aspirin caused a significant increase in COX-2 mRNA expression and a marked increase in COX-2 immunoreactivity, particularly in the superficial mucosa. Expression of COX-1 (mRNA and protein) was unaffected by aspirin, as were NOS mRNA expression and enzyme activity. Pre-treatment with prostaglandin E2 prevented the induction of COX-2 by aspirin. Salicylate and indomethacin caused modest increases in COX-2 immunoreactivity but no change in COX-2 mRNA. Neither concentration of ethanol affected COX-2 mRNA or protein expression, suggesting that this was a specific response to the aspirin, rather than to injury. CONCLUSIONS: These results demonstrate a rapid up-regulation of COX-2 expression in response to aspirin, possibly representing a compensatory response to inhibition of gastric prostaglandin synthesis.

Distribution and function of brain natriuretic peptide in the stomach and small intestine of the rat.

The distribution and function of brain natriuretic peptide (BNP) was studied in the rat stomach and jejunum. BNP-like immunoreactive nerves were found in the myenteric plexus, circular muscle, submucosa and in the crypt region of the jejunum. In the stomach, BNP-like immunoreactivity was found in the myenteric plexus, circular muscle, submucosa and at the base of the gastric glands. In the submucosa, BNP-like immunoreactivity was often associated with blood vessels. In segments of rat jejunum mounted in Ussing chambers, serosal exposure to rat BNP caused a concentration-dependent increase in short circuit current. A maximal effect of 18 +/- 4 microA/cm2 was observed with 1 microM BNP. The effect was quantitatively and qualitatively similar to that elicited by serosal exposure to equimolar atrial natriuretic peptide. The response to BNP was reduced by 88% in chloride free Kreb's buffer, by 83% in tissues pretreated with cinanserin, an antagonist of the 5-HT2 subtype of the 5-hydroxytryptamine receptor, and by 96% in tissues pretreated with tetrodotoxin, a blocker of axonal conduction. These results are consistent with a physiological role for BNP as a neuromodulator of gastrointestinal electrolyte transport.

Submucosal secretomotor and vasodilator reflexes.

The presence of neuronal reflexes within the intestine that modulate mucosal ion secretion and blood flow have been recognized for many years, but the organization of these reflexes was unclear. This review highlights important findings from recent in vitro guinea-pig studies which have shown that both intrinsic primary afferent neurones (IPANs) and extrinsic primary afferent neurones (EPANs) can respond to chemical and/or mechanical stimuli to activate pathways, the afferent and efferent elements of which are confined to the walls of the intestine. Enteric neuronal pathways involve both myenteric and submucosal plexus neurones whereas capsaicin-sensitive afferent nerves evoke secretion by stimulating submucosal secretomotor neurones and vasodilation by direct actions on the submucosal arterioles. In this review, the cellular mechanisms involved in these pathways are described and the implications of these findings are discussed.

The expression and role of Fas ligand in intestinal inflammation.

Fas ligand (FasL) is involved in the pathogenesis of inflammatory diseases and immune privilege. We examined the expression of FasL in the enteric nervous system (ENS) in murine colitis and guinea-pig ileitis. We studied FasL immunoreactivity, functional integrity of the ENS, severity of colitis, and distribution of neutrophils in wild type and B6/gld mice that lack functional FasL. In ileitis, the distribution of FasL, CD4+ and CD8+ T cells was examined. FasL expression was increased in the ENS of wild type mice with colitis, but decreased labelling of nerve fibres was noted in B6/gld mice. Neutrophils were more abundant and widely distributed in B6/gld mice. Colitis was more severe and persistent in B6/gld mice 7 days after induction. Functional parameters of intestinal secretion and motility in B6/gld mice were the same as controls. In ileitis, FasL expression was increased in the guinea-pig ENS and returned to control levels following the resolution of inflammation. While T cells were not present in the ENS of controls, they were observed during inflammation, but were excluded from ganglia. The number of enteric neurons was unchanged over the course of inflammation. The expression of FasL is altered in intestinal inflammation and contributes to its resolution in experimental colitis.

Gastrointestinal damage induced by platelet-activating factor: role of leukotrienes.

The role of leukotriene synthesis in the gastrointestinal damage induced by platelet-activating factor (PAF) was examined in the rat. The effects of a 20-min infusion of PAF (100 ng/kg per min) on leukotriene B4 (LTB4) and leukotriene C4 (LTC4) synthesis were examined in samples of the stomach, duodenum, jejunum, ileum and colon. Administration of PAF resulted in marked hemoconcentration and extensive hemorrhagic damage which was only observed in the corpus region of the stomach and in the small intestine. However, LTB4 synthesis was increased significantly in all regions studied, while LTC4 synthesis was increased significantly only in the duodenum. Pretreatment of the rats with dexamethasone significantly reduced the PAF-induced increase in LTB4 synthesis in all tissues studied. However, a reduction of PAF-induced damage following dexamethasone treatment was observed in the small intestine, but not the stomach. To further investigate the role of leukotrienes as mediators of PAF-induced gastrointestinal damage, the effects of a 10-min infusion of PAF (100 ng/kg per min i.v.) were compared to those of similar infusions of LTB4, LTC4 or leukotriene D4 (LTD4) (0.3-3 micrograms/kg per min). None of the doses of leukotrienes tested produced hemoconcentration or gastrointestinal damage comparable to that observed with the much lower dose of PAF, with the single exception of significant hemoconcentration observed with the highest dose of LTC4. The results of this study therefore suggest that leukotrienes are unlikely to play a major role as mediators of PAF-induced gastrointestinal damage in the rat.

Mechanisms of platelet-activating factor-induced electrolyte transport in the rat jejunum.

Platelet-activating factor (PAF) is known to cause chloride secretion in the small and large intestine in vitro. The present study investigated the mechanism of action of PAF-induced electrolyte transport in stripped rat jejunal segments mounted in standard Ussing chambers. Short circuit current was monitored as the indicator of active transport. PAF caused a concentration-dependent increase in short circuit current, whereas its precursor, lyso-PAF, did not. The response to 0.2 microM PAF was inhibited by 92% when chloride ion in the bathing solution was replaced. The response was also significantly inhibited by the PAF receptor antagonist, WEB 2170, the cyclooxygenase inhibitor, indomethacin, the phospholipase A2 inhibitor, mepacrine, and the calcium channel blocker, verapamil. In other in vitro experiments, PAF was shown to stimulate jejunal synthesis of prostaglandin E2, but not 6-keto-prostaglandin F1 alpha or the peptidoleukotrienes C4, D4 or E4. In similar experiments, 0.2 microM PAF enhanced the depletion of jejunal mucosal free arachidonic acid as measured by gas chromatography. These results show that platelet-activating factor stimulates chloride transport in the rat jejunum in vitro, and that the response is dependent upon extracellular calcium, the stimulation of phospholipase A2 and the cyclo-oxygenase catalyzed metabolism of arachidonic acid to prostaglandin E2.

Comparison of the effects of endothelin-1 and endothelin-3 on the rat stomach.

The effects of systemic administration of endothelin-1 and endothelin-3 on the susceptibility of the stomach to injury were compared in the anesthetized rat, as were their effects on gastric vascular tone, systemic blood pressure and hematocrit. When infused at concentrations in the 10(-7)-10(-6) M range, endothelin-1 was a far more potent hypertensive agent than endothelin-3. Endothelin-1 caused significant hemoconcentration, while endothelin-3 did not Endothelin-1 was approximately 5- to 10-times more potent as a vasoconstrictor in the stomach and a similar difference in potencies was observed when the ability of these peptides to increase the susceptibility of the stomach to ethanol-induced damage was compared. The two peptides were equipotent in producing gastric mucosal hemorrhage in the absence of any exogenous irritant. These results demonstrate that like endothelin-1, endothelin-3 has ulcerogenic and vasoconstriction actions in the stomach. While there are very large differences in the potencies of the two peptides in terms of producing systemic hypertension and hemoconcentration, the differences in the potency of the gastric ulcerogenic and vasoconstrictor effects are much less marked.

Nitric oxide-donating compounds stimulate electrolyte transport in the guinea pig intestine in vitro.

The role of nitric oxide (NO) as a regulator of intestinal electrolyte transport was investigated in stripped segments of guinea pig intestine mounted in Ussing chambers. Serosal application of the NO-donating compounds sodium nitroprusside or isosorbide dinitrate (in the presence of 5 microM L-cysteine) resulted in concentration-dependent increases in the short circuit current. The response to 0.5 mM nitroprusside was exhibited to the same degree in duodenum, jejunum, ileum and proximal colon, and to a lesser degree in the distal colon. The response to nitroprusside was reduced by pretreatment with either the cyclo-oxygenase inhibitor, indomethacin (45% inhibition), the 5-HT3 antagonist, BRL43694 (30% inhibition) or by incubation with chloride-free buffer (59% inhibition). There was no significant effect of the 5-HT2 receptor antagonist, LY53857, or the neural blocker, tetrodotoxin. Pretreatment of ileal segments with the NO synthase inhibitor, NG-monomethyl-L-arginine, did not significantly alter the short circuit current response to electrical field stimulation compared to controls. Exposure of ileal mucosal scrapings to sodium nitroprusside resulted in a significant increase in cGMP production. The data suggest that exogenous NO-donating compounds can modulate electrolyte transport in the guinea pig intestine in vitro. The response is cyclo-oxygenase-, 5-HT3- and chloride-dependent, and coincides with increases in mucosal cGMP. However, the role of endogenous NO in regulating electrolyte transport remains unclear.

Endothelium-derived relaxing factor (nitric oxide) has protective actions in the stomach.

The role that nitric oxide, an endothelium-derived relaxing factor, may play in the regulation of gastric mucosal defence was investigated by assessing the potential protective actions of this factor against the damage caused by ethanol in an ex vivo chamber preparation of the rat stomach. Topical application of glyceryl trinitrate and sodium nitroprusside, which have been shown to release nitric oxide, markedly reduced the area of 70% ethanol-induced hemorrhagic damage. Topical application of a 0.01% solution of authentic nitric oxide also significantly reduced the severity of mucosal damage. Pretreatment with indomethacin precluded the involvement of endogenous prostaglandins in the protective effects of these agents. The protective effects of NO were transient, since a delay of 5 minutes between NO administration and ethanol administration resulted in a complete loss of the protective activity. The protection against ethanol afforded by 10 micrograms/ml nitroprusside could be completely reversed by intravenous infusion of either 1% methylene blue or 1 mM hemoglobin, both of which inhibit vasodilation induced by nitric oxide. Intravenous infusion of 1% methylene blue significantly increased the susceptibility of the mucosa to damage induced by topical 20% ethanol. These results indicate that ethanol-induced gastric damage can be significantly reduced by nitric oxide. The mechanisms underlying the protective actions of nitric oxide are unclear, but may be related to its vasodilator or anti-aggregatory properties.

Alendronate induces gastric injury and delays ulcer healing in rodents.

Gastric ulceration associated with the use of NSAIDs is most frequently observed in elderly women, the same sector of society most likely to be receiving therapy for osteoporosis. As some anti-osteoporosis medications have been suggested to irritate the upper gastrointestinal mucosa, we evaluated the ability of one such drug, alendronate, to damage the gastric mucosa and to influence the severity and healing of gastric ulcers in rodents. The effects of alendronate on indomethacin-induced antral ulceration was evaluated in the rabbit, while effects on ulcer healing and on the formation of gastric erosions was evaluated in the rat. Effects of alendronate on gastric acid secretion, blood flow and prostaglandin synthesis were also evaluated. Alendronate caused erosions in the rabbit stomach, but not antral ulceration. However, at the highest doses tested (80 mg) alendronate increased the incidence and size of indomethacin-induced antral ulcers. Alendronate also enhanced indomethacin-induced gastric damage in the rat, and delayed gastric ulcer healing. These effects of alendronate were not attributable to changes in gastric acid secretion, blood flow, prostaglandin synthesis or the pharmacokinetics of indomethacin. The damaging effects of alendronate on the stomach were due to topical irritant effects and could be observed at concentrations as low as 4 mg/ml within 30 min of oral administration or topical superfusion. These results support preliminary clinical evidence that alendronate can damage the gastric mucosa. While gastric injury may be a rare occurrence in patients taking this drug, concomitant use of alendronate and NSAIDs may increase the incidence or severity of ulceration.

Radiation-induced acute intestinal inflammation differs following total-body versus abdominopelvic irradiation in the ferret.

PURPOSE: The studies were designed to investigate the differences in the intestinal inflammatory response following abdominopelvic or total-body irradiation in a ferret model. MATERIALS AND METHODS: Ferrets were exposed either to total-body or to abdominopelvic gamma-radiation (5 Gy) and various parameters of inflammation studied in the jejunum, ileum and colon 2 and 7 days later. RESULTS: Abdominopelvic and, to a greater extent, total-body irradiation caused weight loss by 7 days. White blood cell counts were reduced in both groups, but more so following total-body irradiation. Myeloperoxidase activity was significantly increased in the ileum 2 days after abdominopelvic irradiation, but it was reduced after total-body irradiation. Total-body irradiation increased tissue prostaglandin E2 levels in all regions at 2 days and decreased jejunal leukotriene B4 levels in the jejunum at both time points. Ileal prostaglandin E2 levels were increased 2 days after abdominopelvic irradiation. Expression of inducible nitric oxide synthase was not altered by either irradiation protocol. CONCLUSIONS: The data show that there are regional differences in the intestinal response to irradiation, depending on whether it was delivered to the whole body or locally to the abdominopelvic region. In particular, the ileum exhibited an acute increase in myeloperoxidase activity following abdominopelvic but not total-body irradiation.

Exposure to ionizing radiation modifies neurally-evoked electrolyte transport and some inflammatory responses in rat colon in vitro.

PURPOSE: To characterize the responsiveness of the colon to neural stimulation following acute exposure of rats to gamma-radiation and to correlate observed changes to a number of parameters. MATERIALS AND METHODS: Rats were exposed to 5 or 10 Gy 137Cs gamma-radiation or not (sham-irradiated) and studied at 1, 3 and 7 days after irradiation. Stripped segments of colon were mounted in Ussing chambers for measurements of neurally-evoked electrolyte transport (electrical field stimulation). Colonic tissue was also taken for biochemical (tissue 5-hydroxytryptamine, histamine, leukotriene B4, nitric oxide synthase) and histological analyses (mast cells). RESULTS: In irradiated rats both proximal and distal colon were hyporesponsive to electrical field stimulation at 1 and 3 days, but had recovered by 7 days. In the distal colon, carbachol responses were attenuated 1 day after 10 Gy. Mast cells, tissue histamine and leukotriene B4 synthesis were significantly reduced at all time points but no changes were seen in 5-HT or inducible NOS activity. CONCLUSIONS: Rat colon becomes hyporesponsive to neural stimuli post-irradiation. The response initially (1 and 3 days) correlates with decreased mast cells and histamine, but not at 7 days.

Expression, activity and cellular localization of inducible nitric oxide synthase in rat ileum and colon post-irradiation.

PURPOSE: Studies were conducted to determine the acute effect of exposure to ionizing radiation on inducible nitric oxide synthase (iNOS) activity and expression in the rat ileum and colon. MATERIALS AND METHODS: Rats received whole body exposure to 10 Gy gamma-radiation and were studied 0.5-48 h later. Segments of ileum and colon were taken from anaesthetized rats for determination of myeloperoxidase activity (a marker of acute inflammation), and iNOS mRNA expression, enzyme activity and localization. RESULTS: Myeloperoxidase activity in ileum was not increased compared with shams until 48 h post-irradiation. In colon, myeloperoxidase activity was lower than shams at 48 h post-irradiation. Irradiation resulted in a dexamethasone-sensitive expression of iNOS mRNA in both the ileum and colon within 2h. Inducible NOS activity was significantly elevated in the ileum, but not in the colon. The elevated ileal nitric oxide synthase activity was significantly reduced by pretreatment with the iNOS inhibitor, aminoguanidine. Immunoreactivity for iNOS protein was localized to the epithelium and was apparent at 2-6 h post-irradiation in the ileum, but not the colon. CONCLUSIONS: Exposure to ionizing radiation results in the expression of iNOS in ileum and colon, but only significantly increases iNOS activity in the ileum. Inducible NOS-derived NO may participate in acute, whole body radiation-induced ileal dysfunction, independently of the development of an inflammatory response.

Exposure to ionizing radiation increases responsiveness to neural secretory stimuli in the ferret jejunum in vitro.

Experiments were designed to determine the effects of ionizing radiation on jejunal epithelial function in the ferret in vitro. Basal and stimulated electrolyte transport were determined in Ussing chambers at 0.5, 2, 24 and 48 h post-irradiation. Tissue histamine and 5-hydroxytryptamine levels were measured. Myeloperoxidase activity was also measured as an index of inflammation. Basal short circuit current was reduced at 2 h post-irradiation, but was elevated at 48 h. Basal conductance was significantly increased by 24 and 48 h. Responsiveness to electrical field stimulation was depressed at 0.5 h, and was greater than control by 24 and 48 h post-irradiation. Similarly, short circuit current responses to prostaglandin E2 were depressed at 0.5 h and elevated at 24 h. No significant change was observed in the response to carbachol post-irradiation, indicating that alterations in responsiveness were not likely at the level of the enterocyte. Changes in responsiveness to electrical field stimulation correlated significantly with increases in mucosal mast cell numbers. Myeloperoxidase activity, indicative of neutrophil infiltration, did not increase post-irradiation, nor was there histological evidence of an inflammatory cell infiltrate. There were no changes in tissue histamine or 5-hydroxytryptamine. Histology also revealed little microscopic morphological change from shams in tissue from irradiated ferrets. The results of this study demonstrate effects of irradiation on electrolyte transport in the ferret jejunum. The enhanced neurally evoked electrolyte transport observed at 24-48 h post-irradiation was not correlated with the development of inflammation, but was correlated with changes in mast cell numbers.

Attenuation of Clostridium difficile toxin-induced damage to epithelial barrier by ecto-5'-nucleotidase (CD73) and adenosine receptor signaling.

BACKGROUND: Clostridium difficile (Cdf) releases toxins (TcdA and TcdB) that damage the intestinal epithelial barrier. Ecto-5'-nucleotidase (CD73) is expressed on intestinal epithelial cells, and it is hypothesized to protect against toxin-induced epithelial damage through the cleavage of 5'-AMP to adenosine (Ado) and subsequent activation of adenosine receptors (AdoRs). Herein, we sought to assess the potential protective effects of CD73 and AdoR signaling on the injurious effects of Cdf toxins. METHODS: Barrier function was assessed with T84 colonocytes. Transepithelial electrical resistance (TEER), paracellular fluorescein isothiocyanate (FITC)-dextran flux, and tight junction protein (ZO-1) integrity were monitored. Intrarectal installation of Cdf toxin was used to assess epithelial damage in vivo. KEY RESULTS: TcdA/B caused reduced TEER and increased paracellular flux in vitro. Concurrent treatment with 5'-AMP attenuated these responses to Cdf toxin; an effect that was blocked with ZM241385 (AdoRA2 antagonist). APCP, a CD73 inhibitor, also suppressed the protective effects of 5'-AMP on paracellular flux. 5'-AMP reduced toxin-induced disruption of ZO-1, an effect that was abolished by APCP and ZM241385. Inhibition of CD73 with APCP during Cdf toxin exposure led to increased intestinal barrier permeability and epithelial damage in vivo. Intrarectal instillation of 5'-AMP had no effect on toxin-induced intestinal injury. CONCLUSIONS & INFERENCES: Our data suggest that CD73 has a protective role against TcdA/B-induced damage. 5'-AMP treatment attenuated the damaging effects of Cdf toxin in vitro, and inhibitors of CD73 (APCP) and AdoRs (ZM241385) revealed that the cleavage of 5'-AMP to Ado was necessary for the protective effects. Inhibition of CD73 in vivo increases colonic tissue damage and epithelial permeability during Cdf toxin exposure.

Differential effects of salvinorin A on endotoxin-induced hypermotility and neurogenic ion transport in mouse ileum.

BACKGROUND: Salvinorin A (SA) is the principal active ingredient of Salvia divinorum, with an established inhibitory action on gastrointestinal (GI) transit and colonic ion transport in mice. Under normal conditions, the effects of SA are mediated by kappa opioid (KOR) and cannabinoid (CB1 and CB2) receptors. However, the role of SA in pathophysiological conditions remains unresolved. The aim of this study was to characterize the in vitro and in vivo effects of SA on mouse ileum after endotoxin challenge. METHODS: Changes in GI motility were studied in vitro, using smooth muscle preparations from the mouse ileum. In vivo, the fecal pellet output and small intestinal fluid content were measured. Neurogenic ion transport and intestinal permeability were examined using Ussing chambers. In addition, Western blot analysis of mucosa was performed and plasma nitrite/nitrate levels were determined. KEY RESULTS: Salvinorin A inhibited endotoxin-induced ileal hypercontractility via KOR, CB1, and CB2 receptors. Neurogenic ion transport, which was significantly reduced after endotoxin challenge, was normalized by SA through a nitric oxide synthase (NOS)-dependent mechanism. Western blot analysis and plasma nitrite/nitrate level quantitation confirmed the involvement of NOS in the regulatory action of SA. CONCLUSIONS & INFERENCES: This is the first report showing differential effects of SA on motor and secretory activity in mouse GI during endotoxemia. The outcomes of our study imply possible novel applications of SA and its analogs in the treatment of GI disorders.