Enteropathy In Rats Research Articles

Lafutidine Ameliorates Indomethacin-Induced Small Intestinal Damage in Rats by Modifying the Intestinal Mucosal Barrier, Inflammation, and Microbiota

Introduction: Nonsteroidal anti-inflammatory drug (NSAID)-induced small intestinal damage is a serious and escalating clinical problem without effective treatment. Lafutidine (LAF) is a novel histamine H2 receptor antagonist with a mucosal protective action. This study aimed to investigate the protective effect of LAF on indomethacin (IND)-induced enteropathy in rats. Methods: Rats were treated with LAF for 10 days with concomitant IND treatment on the final 5 days. Changes in metabolism and hematological and biochemical parameters were measured, and intestinal damage was blindly scored. Intestinal mucosal tissue and luminal contents were collected for transcriptome and microbiota sequencing. Intestinal inflammation and barrier function were also evaluated. Results: LAF treatment prevented anorexia and weight loss in rats and ameliorated reductions in hemoglobin, hematocrit, total protein, and albumin levels. LAF reduced the severity of IND-induced intestinal damage including macroscopic and histopathological damage score. Transcriptome sequencing results indicated that LAF might have positive effects on intestinal inflammation and the intestinal mucosal barrier. Further research revealed that LAF decreased neutrophil infiltration, and IL-1β and TNF-α expression in intestinal tissue. Besides, the treatment increased mucus secretion, MUC2, Occludin, and ZO-1 expression, and decreased serum D-lactate levels. LAF treatment also ameliorates microbial dysbiosis in small intestine induced by IND and increased the abundance of Lactobacillus acidophilus. Conclusion: LAF may protect against NSAID enteropathy via enhancing the intestinal mucosal barrier, inhibiting inflammation, and regulating microbiota.

Mitigation of Diclofenac Sodium–Induced Hepatic Injury and Enteropathy in Rats by Vanillin

Mitigation of Diclofenac Sodium–Induced Hepatic Injury and Enteropathy in Rats by Vanillin

Trichopus zeylanicus ameliorates ibuprofen inebriated hepatotoxicity and enteropathy: an insight into its modulatory impact on pro/anti-inflammatory cytokines and apoptotic signaling pathways.

Ibuprofen is a nonsteroidal anti-inflammatory drug that is commonly used for its analgesic, antipyretic and anti-inflammatory effects worldwide. However ibuprofen comes with serious unavoidable adverse effects on various organs when used for long duration or overdosed. Trichopus zeylanicus is a medicinal plant endemic to India owning various beneficial properties and is been used in treating various ailments. Therefore, the objective of this study was to evaluate the ameliorative effect of aqueous leaves’ extract of Trichopus zeylanicus against ibuprofen-induced hepatic toxicity and enteropathy in rats. Overall in this study 30 male albino rats were used, which were divided into five groups (six in each group). Group-I was normal control, Group-II was ibuprofen (400 mg/kg/day) inebriated group, Group-III was silymarin (25 mg/kg/day) pretreated + ibuprofen (400 mg/kg/day), Group-IV was ALETZ (1000 mg/kg/day) pretreated + ibuprofen (400 mg/kg/day), and Group-V was ALETZ alone (1000 mg/kg/day) group. The duration of the administration was for five days, followed by scarifying rats on the sixth day. Later the rats were assessed for liver and intestine enzyme markers, antioxidant parameters along with histopathological changes. In addition the pro-inflammatory markers such as TNF-α, IL-6 and IL-1β as well as anti-inflammatory cytokine IL-10 levels were measured using ELISA. Lastly the expression pattern of apoptotic signaling markers such as caspase-3, caspase-8 and Bcl-2 was evaluated using western blot. The results obtained from this study showed changes in levels of aforesaid parameter which presented the toxic effect of ibuprofen on liver and small intestine. Pre-treatment of ALETZ in ibuprofen-inebriated group was able to normalize the adverse effect caused due to ibuprofen. The conclusion of the study deduces that pre-treatment with ALETZ alleviates by modulating oxidative stress, inflammation, and apoptosis in ibuprofen inebriated rats, indicating its protective mechanism.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s10787-022-01052-5.

Synthesis, characterization and evaluation of resveratrol-loaded functionalized carbon nanotubes as a novel delivery system in radiation enteropathy

Radiation-induced enteropathy is a major clinical challenge during radiotherapy. Resveratrol displays beneficial pharmacological activities; however, low oral bioavailability limits its effectiveness. This study aims at preparing methacrylic acid (MAAc) functionalized multi-walled carbon nanotubes (MWCNTs-MAAc) as carriers for pH triggered controlled release of resveratrol in an effort to improve the drug therapeutic potential. MWCNTs-MAAc were prepared using radiation technique and then characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) spectroscopy. In vitro drug release profile at different pH values was analyzed. Furthermore, the designed RES-MWCNTs-MAAc nanocomplex was evaluated against radiation-induced enteropathy in rats. Oral administration of RES-MWCNTs-MAAc restored colonic redox state and elevated antioxidant enzymes activities glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) and reduced colonic inflammatory mediators tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interferone-γ (IFN-γ) contents in addition to declining the intrinsic apoptotic pathway as evidenced by down-regulation of Bax and caspase-3 proteins expression accompanied by up-regulation of Bcl-2 protein expression. RES-MWCNTs-MAAc was more efficient than free resveratrol due to the delivery system that allowed prolonged resveratrol release at target site. Thus, this formulation could serve as a beneficial anti-inflammatory approach for patients during radiotherapy.

Glycomacropeptide Ameliorates Indomethacin-Induced Enteropathy in Rats by Modifying Intestinal Inflammation and Oxidative Stress.

Nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy is considered a serious and increasing clinical problem without available treatment. Glycomacropeptide (GMP) is a 64-amino acid peptide derived from milk κ-casein with numerous biological activities. The aim of this study was to investigate the protective effect of GMP on NSAID enteropathy in rats. Enteropathy was induced by seven days oral indomethacin administration. Rats were orally GMP treated from seven days previous and during the establishment of the enteropathy model. Changes in metabolism, hematological and biochemical blood alterations, intestinal inflammation and oxidative damage were analyzed. Integrity barrier markers, macroscopic intestinal damage and survival rate were also evaluated. GMP treatment prevented anorexia and weight loss in animals. Furthermore, prophylaxis with GMP ameliorated the decline in hemoglobin, hematocrit, albumin and total protein levels. The treatment had no therapeutic efficacy on the decrease of occludin and mucin (MUC)-2 expression in intestinal tissue. However, GMP markedly decreased neutrophil infiltration, and CXCL1, interleukin-1β and inducible nitric oxide synthase expression. Nitric oxide production and lipid hydroperoxide level in the small intestine were also diminished. These beneficial effects were mirrored by preventing ulcer development and increasing animal survival. These results suggest that GMP may protect against NSAID enteropathy through anti-inflammatory and antioxidant properties.

EFFECT OF AMLODIPINE ON ENTEROPATHY INDUCED BY INDOMETHACIN IN RATS

Objective: Non-steroidal anti-inflammatory drugs (NSAIDs) have become well known for causing gastroduodenal mucosal damage. In addition, they are also known to affect the small intestine in humans. Amlodipine is a third-generation dihydropyridine-type calcium channel blocker; it can inhibit inflammatory cytokines and enhance antioxidant defenses. The aim of this study was to evaluate the effect of Amlodipine on indomethacin-induced enteropathy in rats.
 Methods: Enteropathy was induced by subcutaneous indomethacin (Indo) prepared in 5 % sodium bicarbonate administrated at a dose rate of 9 mg/kg for two days at 24h intervals. Amlodipine (10 mg/Kg body weight po) was administrated for seven consecutive days beginning 24 h after the first Indo injection. Rats were sacrificed under ether anesthesia on the 8th day. The small intestinal injury was assessed by body weight loss, small intestine weight/length ratio, macroscopic damage, histological study, as well as by biochemical measurement of reduced glutathione (GSH), lipid peroxides and superoxide dismutase (SOD) activity in the small intestine tissue.
 Results: The results showed that Amlodipine didn't decrease body weight loss, it decreased small intestine weight/length ratio, macroscopic and microscopic small intestinal damage scores caused by administration of Indo. It also increased SOD activity and decreased lipid peroxidation. The effect on the level of GSH wasn't observed. No statistical significance was observed when previous findings were compared to Indo induced enteropathy group (p>0.05).
 Conclusion: Amlodipine didn't produce an obvious enhancement in enteropathy induced by Indo in rats.

Influence of adrenalectomy on protective effects of urocortin I, a corticotropin-releasing factor (CRF)-related peptide, against indomethacin-induced enteropathy in rats

The influence of adrenalectomy on indomethacin-induced enteropathy in rats was examined and the possible involvement of adrenal glucocorticoids in protective effects of urocortin I, a CRF agonist, was investigated. Male SD rats were administered indomethacin (10 mg/kg) s.c., killed 24 h later, and small intestines were examined for hemorrhagic lesions. Urocortin I (20 μg/kg) was given i.v. 10 min before indomethacin. Bilateral adrenalectomy was performed a week before the experiment. Indomethacin caused hemorrhagic lesions in small intestines, accompanied by intestinal hypermotility, enterobacterial invasion and iNOS expression. Adrenalectomy markedly increased ulcerogenic and motility responses caused by indomethacin, with further enhanced bacterial invasion and iNOS expression. This worsening effect was reproduced by pretreatment with mifepristone. Urocortin I prevented indomethacin-induced enteropathy; this effect was abrogated by astressin 2B, a CRF2 receptor antagonist, but was not affected by either adrenalectomy or mifepristone pretreatment. These results suggest that adrenalectomy aggravates indomethacin-induced enteropathy, and intestinal hypermotility response may be the key element in the mechanism underlying this aggravation, while endogenous glucocorticoids play a role in intestinal mucosal defense against these lesions but do not account for protective effects of urocortin I, which are mediated by peripheral CRF2 receptors.

Rifaximin prevents diclofenac-induced enteropathy in rats through antibacterial and anti-inflammatory activities

Rifaximin prevents diclofenac-induced enteropathy in rats through antibacterial and anti-inflammatory activities

Цитопротективна дія донорів гідрогену сульфіду в слизовій оболонці тонкої кишки за індометацин- індукованих ентеропатій у щурів

Цитопротективна дія донорів гідрогену сульфіду в слизовій оболонці тонкої кишки за індометацин- індукованих ентеропатій у щурів

Influence of Adrenalectomy on Protective Effects of Urocortin I, a Corticotropin-Releasing Factor, Against Indomethacin-Induced Enteropathy in Rats.

We examined the influence of adrenalectomy on NSAID-induced small intestinal damage in rats and investigated the possible involvement of adrenal glucocorticoids in the protective effects of urocortin I, a corticotropin-releasing factor (CRF) agonist. Male SD rats without fasting were administered indomethacin s.c. and killed 24 h later in order to examine the hemorrhagic lesions that developed in the small intestine. Urocortin I (20 µg/kg) was given i.v. 10 min before the administration of indomethacin. Bilateral adrenalectomy was performed a week before the experiment. Indomethacin (10 mg/kg) caused multiple hemorrhagic lesions in the small intestine, which were accompanied by a decrease in mucus secretion and increases in intestinal motility, enterobacterial invasion, and iNOS expression. Adrenalectomy markedly increased the ulcerogenic and motility responses caused by indomethacin, with further enhancements in bacterial invasion and iNOS expression; severe lesions occurred at 3 mg/kg, a dose that did not induce any damage in sham-operated rats. This worsening effect was also observed by the pretreatment with mifepristone (a glucocorticoid receptor antagonist). Urocortin I prevented indomethacin-induced enteropathy, and this effect was completely abrogated by the pretreatment with astressin 2B, a CRF2 receptor antagonist, but was not significantly affected by either adrenalectomy or the mifepristone pretreatment. These results suggested that adrenalectomy aggravated the intestinal ulcerogenic response to indomethacin, the intestinal hypermotility response may be a key element in the mechanism for this aggravation, and endogenous glucocorticoids played a role in intestinal mucosal defense against indomethacin-induced enteropathy, but did not account for the protective effects of urocortin I, which were mediated by the activation of peripheral CRF2 receptors

Ciprofloxacin blocked enterohepatic circulation of diclofenac and alleviated NSAID-induced enteropathy in rats partly by inhibiting intestinal β-glucuronidase activity.

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID), which may cause serious intestinal adverse reactions (enteropathy). In this study we investigated whether co-administration of ciprofloxacin affected the pharmacokinetics of diclofenac and diclofenac-induced enteropathy in rats. The pharmacokinetics of diclofenac was assessed in rats after receiving diclofenac (10 mg/kg, ig, or 5 mg/kg, iv), with or without ciprofloxacin (20 mg/kg, ig) co-administered. After receiving 6 oral doses or 15 intravenous doses of diclofenac, the rats were sacrificed, and small intestine was removed to examine diclofenac-induced enteropathy. β-Glucuronidase activity in intestinal content, bovine liver and E coli was evaluated. Following oral or intravenous administration, the pharmacokinetic profile of diclofenac displayed typical enterohepatic circulation, and co-administration of ciprofloxacin abolished the enterohepatic circulation, resulted in significant reduction in the plasma content of diclofenac. In control rats, β-glucuronidase activity in small intestinal content was region-dependent: proximal intestine<distal intestine<ileal valve. Administration of ciprofloxac caused significant reduction of β-glucuronidase activity in distal small intestine, and particularly in ileal valve. Furthermore, ciprofloxacin (10-2000 μmol/L) dose-dependently inhibited β-glucuronidase activity in distal small intestine content or E coli incubated in vitro, but did not affect that in proximal small intestine content or bovine liver incubated in vitro. After receiving 6 oral doses or 15 intravenous doses of diclofenac, typical enteropathy was developed with severe enteropathy occurred in distal small intestine. Co-administration of ciprofloxacin significantly alleviated diclofenac-induced enteropathy. Co-administration of ciprofloxacin attenuated enterohepatic circulation of diclofenac and alleviated diclofenac-induced enteropathy in rats, partly via the inhibition of intestinal β-glucuronidase activity.

Protective effect of rabamipide on non-steroid anti-inflammatory drug induced enteropathy in rats

Protective effect of rabamipide on non-steroid anti-inflammatory drug induced enteropathy in rats

Prophylactic Effect of Monosodium Glutamate on NSAID-Induced Enteropathy in Rats

We reviewed the prophylactic effect of monosodium glutamate (MSG), a substance known as the "umami", on NSAID-induced small intestinal damage in rats. Loxoprofen, one of the NSAIDs frequently used in Asian countries, given orally at 60 mg/kg, caused hemorrhagic damage in the small intestine, mainly jejunum and ileum, concomitant with a down-regulation of Muc2 expression/ mucus secretion and an up-regulation of enterobacterial invasion and neutrophil migration as well as inducible nitric oxide synthase (iNOS) expression. The severity of these lesions was reduced by pretreatment with MSG (0.1~5%) given as a mixture of powder food (10 g/rat/day) for 5 days before administration of loxoprofen. The effect of MSG was accompanied by an up-regulation of Muc2 expression/ mucus secretion as well as a suppression of bacterial invasion, iNOS expression and myeloperoxidase activity. On the other hand, these lesions spontaneously healed within 7 days, but this process was hampered by loxoprofen at low doses (>10 mg/kg) given repeatedly for 5 days after ulceration. The healing-impairment effect of loxoprofen was accompanied by the down-regulation of vascular endothelium- derived growth factor (VEGF) expression and angiogenic response, and these responses were all antagonized by feeding diet containing 5% MSG for 5 days after ulceration. It is suggested that MSG exhibits a prophylactic effect against loxoprofen-induced small intestinal lesions, this effect is functionally associated with the up-regulation of Muc2 expression/mucus secretion, resulting in suppression of enterobacterial invasion and iNOS expression, the major pathogenic events in NSAID-induced enteropathy, and MSG also has the healing promoting effect on these lesions through enhancement of VEGF expression and angiogenesis.

NSAID–PPI Enteropathy in Humans

The comprehensive studies by Wallace et al1Wallace J.L. et al.Gastroenterology. 2011; 141: 1314-1322Abstract Full Text Full Text PDF PubMed Scopus (364) Google Scholar strongly support a co-enhancement by nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPIs) in the development of enteropathy in rats, with the PPI contribution largely mediated through its alteration of small intestinal bacterial flora. A variety of observations support the presence of similar phenomena in human subjects, and suggest that NSAID–PPI enteropathy may be a frequent, but unappreciated, illness in clinical practice. Compare et al2Compare D. et al.Eur J Clin Invest. 2011; 41: 380-386Crossref PubMed Scopus (87) Google Scholar reported diarrhea, often associated with other prominent gastrointestinal symptoms, in 53% of 42 patients after 6 months of PPI therapy, with small intestinal bacterial overgrowth in 62% of them. Lombardo et al3Lombardo J. et al.Clin Gastroenterol Hepatol. 2010; 8: 504-508Abstract Full Text Full Text PDF PubMed Scopus (237) Google Scholar reported similar phenomena among 40%–50% of 200 adults who had consumed PPI medications for an average of 36 months, with diarrhea eliminated or improved in 94% after 2 weeks of oral rifaximin therapy. In neither study was the use of NSAIDs by their subjects analyzed. Both Goldstein et al4Goldstein J.L. et al.Clin Gastroenterol Hepatol. 2005; 3: 133-141Abstract Full Text Full Text PDF PubMed Scopus (572) Google Scholar and Hawkey et al5Hawkey C.J. et al.Clin Gastroenterol Hepatol. 2008; 6: 536-544Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar have independently reported more frequent small intestinal injury in healthy volunteers consuming a combination of NSAID and omeprazole for 14–16 days, in comparison with those consuming a selective cyclooxygenase (COX)-2 inhibitor, supporting the presence of an independent PPI contribution to their injury, since multiple other studies have demonstrated similar small bowel damage induced by therapeutic doses of conventional NSAIDs and COX-2 inhibitors. Microscopic colitis is reported to be more common among both PPI and NSAID consumers6Wilcox G.M. et al.J Clin Gastroenterol. 2009; 43: 551-553Crossref PubMed Scopus (54) Google Scholar, 7Keszthelyi D. et al.Ailment Phamacol Ther. 2010; 32: 1124-1128Crossref PubMed Scopus (87) Google Scholar, 8Pardi D.S. et al.Gastroenterology. 2011; 140: 1155-1165Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar with its strongest association among older adults consuming both classes of medication concurrently.8Pardi D.S. et al.Gastroenterology. 2011; 140: 1155-1165Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar Both classes of medications are widely prescribed and also available without prescription. In my small, solo practice of general internal medicine, over a recent 2-month interval, 6 patients were identified with apparent NSAID–PPI diarrhea of 2–12 months’ duration, each of whom responded dramatically within 2 weeks to withdrawal of the offending medications without other medicinal or dietary therapy. Additional studies exploring these associations on humans should receive high priority, and patients with diarrhea, abdominal distention, flatulence, or abdominal pain while consuming medications of both classes should undergo reassessment of their diagnoses and therapy. Proton Pump Inhibitors Exacerbate NSAID-Induced Small Intestinal Injury by Inducing DysbiosisGastroenterologyVol. 141Issue 4PreviewProton pump inhibitors (PPIs) and nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used classes of drugs, with the former frequently coprescribed to reduce gastroduodenal injury caused by the latter. However, suppression of gastric acid secretion by PPIs is unlikely to provide any protection against the damage caused by NSAIDs in the more distal small intestine. Full-Text PDF ReplyGastroenterologyVol. 142Issue 4PreviewWe thank Dr Daniell for his insightful remarks about our paper on the exacerbation of NSAID-induced enteropathy in rodents by proton pump inhibitors (PPIs).1 He has provided references to several studies in which data were generated that are consistent with our hypotheses that PPIs can worsen NSAID-induced small intestinal injury, and that the underlying mechanism is the PPI-induced shift in quantity and types of bacteria in the small intestine. Two additional studies are worthy of mention. Poullis et al2 reported that fecal levels of calprotectin, a marker of gut inflammation, were significantly elevated in patients taking PPIs. Full-Text PDF

Electrical biopsy of irradiated intestinal tissue with a simple electrical impedance spectroscopy system for radiation enteropathy in rats—a pilot study

Electrical impedance is one of the most often used parameters for characterizing material properties, especially in biomedical applications. Electrical impedance spectroscopy (EIS), used for revealing both resistive and capacitive characteristics, is good for use in tissue characterization. In this study, a portable and simple EIS system based on a commercially available chip was used to assess rat intestinal tissues following irradiation. The EIS results were fitted to a resistor and capacitor electrical circuit model to solve the electrical properties of the tissue. The variation in the tissue's electrical characteristics was compared to the morphological and histological findings. From the experimental results, it was clear that the electrical properties, based on receiver operation curve analysis, demonstrated good detection performance relative to the histological changes. The electrical parameters of the tissues could be used to distinguish the tissue's status for investigation, which introduced a concept of ‘electrical biopsy’, and this ‘electrical biopsy’ approach may be used to complement histological examinations.

Pravastatin Inhibits the Rho/CCN2/Extracellular Matrix Cascade in Human Fibrosis Explants and Improves Radiation-Induced Intestinal Fibrosis in Rats

Intestinal complications after radiotherapy are caused by transmural fibrosis and impair the quality of life of cancer survivors. Radiation fibrosis was considered permanent and irreversible, but recently, its dynamic nature was shown, providing new opportunities for the development of antifibrotic therapies. Among these new targets, we identified the Rho/ROCK pathway and thought to investigate whether pravastatin treatment inhibits Rho pathway activation and elicits an antifibrotic action. Rho and ROCK activities were monitored in human explants presenting radiation fibrosis remodeling after incubation with pravastatin. Subsequent modulation of CCN2, type I collagen, and fibronectin expression were assessed ex vivo and in intestinal smooth muscle cells derived from radiation enteropathy. Then, the therapeutic relevance of the antifibrotic action of pravastatin was explored in vivo in a rat model of chronic radiation fibrosis (19 Gy X-rays) treated with 30 mg/kg/d pravastatin in the drinking water. The results obtained with human explants show that pravastatin specifically inhibits Rho activity in submucosal mesenchymal cells. Pravastatin also elicits ROCK inhibition, and subsequent CCN2 production in human explants and smooth muscle cells isolated from radiation enteropathy. Inhibition of type I collagen and fibronectin does occur, showing that pravastatin modulates the secretory phenotype of mesenchymal cells. Lastly, curative pravastatin administration improves radiation enteropathy in rats. This structural improvement is associated with decreased deposition of CCN2 and subsequent decreased extracellular matrix deposition. Targeting established fibrosis with pravastatin is an efficient and safe antifibrotic strategy in radiation-induced enteropathy, and is easily transferable into the clinic.

Successful Mitigation of Delayed Intestinal Radiation Injury Using Pravastatin is not Associated with Acute Injury Improvement or Tumor Protection

To investigate whether pravastatin mitigates delayed radiation-induced enteropathy in rats, by focusing on the effects of pravastatin on acute cell death and fibrosis according to connective tissue growth factor (CTGF) expression and collagen inhibition. Mitigation of delayed radiation-induced enteropathy was investigated in rats using pravastatin administered in drinking water (30 mg/kg/day) 3 days before and 14 days after irradiation. The ileum was irradiated locally after surgical exteriorization (X-rays, 19 Gy). Acute apoptosis, acute and late histologic alterations, and late CTGF and collagen deposition were monitored by semiquantitative immunohistochemistry and colorimetric staining (6 h, 3 days, 14 days, 15 weeks, and 26 weeks after irradiation). Pravastatin antitumor action was studied in HT-29, HeLa, and PC-3 cells by clonogenic cell survival assays and tumor growth delay experiments. Pravastatin improved delayed radiation enteropathy in rats, whereas its benefit in acute and subacute injury remained limited (6 h, 3 days, and 14 days after irradiation). Delayed structural improvement was associated with decreased CTGF and collagen deposition but seemed unrelated to acute damage. Indeed, the early apoptotic index increased, and severe subacute structural damage occurred. Pravastatin elicited a differential effect, protecting normal intestine but not tumors from radiation injury. Pravastatin provides effective protection against delayed radiation enteropathy without interfering with the primary antitumor action of radiotherapy, suggesting that clinical transfer is feasible.

5-Aminosalicylic Acid Improves Indomethacin-Induced Enteropathy by Inhibiting iNOS Transcription in Rats

Nitric oxide has been implicated in the pathogenic mechanism of inflammatory bowel disease states. We evaluated indomethacin-induced enteropathy in rats, in relation to the expression of the inducible isoform of NO synthase (iNOS) using aminosalicylic acid (5-ASA), its isomer 4-ASA (10 or 50 mg/kg/day, po), and dexamethasone, an iNOS transcription inhibitor (3 mg/kg/day, sc). Enteropathy was induced by indomethacin (7.5 mg/kg/day, sc) for two days and the small intestine was examined for lesions over the next 14 days. Indomethacin-induced small-intestinal ulcer size, mucosal myeloperoxidase activity, iNOS expression and serum nitrite/nitrate levels were maximally increased by day 4 and gradually decreased by day 14. Treatment with 5-ASA, but not 4-ASA, decreased indomethacin-induced ulcer length, myeloperoxidase activity, serum nitrite/nitrate levels and iNOS expression at day 4. Dexamethasone had a greater effect than 5-ASA in reducing myeloperoxidase activity and ulcer length by 26 and 32%, respectively. Dexamethasone also reduced serum nitrate/nitrite and iNOS expression to their basal levels. In conclusion, inhibition of iNOS expression by 5-ASA appears to be associated with diminished intestinal ulceration in indomethacin-induced enteropathy.

Microcirculatory Changes in Experimental Mesenteric Longitudinal Ulcers of the Small Intestine in Rats

Rats receiving intracolonic administration of indomethacin develop longitudinal ulcers on the mesenteric side of the small intestine that are similar to those seen in the acute phase of Crohn's disease. To investigate the causative role of microcirculatory disturbances and to elucidate the therapeutic effect of antioxidants on this enteropathy in rats, we serially evaluated changes in regional blood flow of the small intestine using laser Doppler perfusion imaging and the colored microsphere injection method. Both methods disclosed stepwise hyperperfusion limited to the mesenteric side of the small intestine following transient ischemia during the initial 30-60 minutes. In addition, both a radical scavenger and a radical production inhibitor significantly ameliorated the mesenteric longitudinal ulcers. We concluded that ischemia-reperfusion on the mesenteric side accompanying excessive production of radicals might be strongly involved in indomethacin-induced longitudinal ulcers of the small intestine in rats.

Hyperbaric Oxygenation Ameliorates Indomethacin-Induced Enteropathy in Rats by Modulating TNF-α and IL-1β Production

The effect of hyperbaric oxygenation (HBO2) was investigated in a rat model of indomethacin-induced enteropathy. Enteropathy was induced by two subcutaneous injections of indomethacin (7.5 mg/kg) 24 hr apart. Six groups of rats (n=8) were treated with and without HBO2 (100% oxygen at 2.3 atm absolute) for 1 hr once or twice a day for 2 or 5 days. Disease activity index (DAI) and total ulcer length were measured. Other rats were randomized into two groups (n=16) with and without HBO2 (1 hr once a day) and four rats were killed in each group at 12, 24, 48, and 72 hr after the final injection of indomethacin. Serum and intestinal mucosal TNF-alpha, IL-1beta, myeloperoxidase (MPO), and iNOS expression was measured. HBO2 treatment significantly attenuated indomethacin -induced intestinal ulceration and improved DAI. Indomethacin increased MPO activity and iNOS expression, and these were reduced by HBO2 treatment, with a concomitant reduction in TNF-alpha and IL-1beta. Our data suggest that HBO2 treatment has a beneficial effect on indomethacin-induced enteropathy and this effect is possibly mediated by decreased production of TNF-alpha and IL-1beta.