Classic NSAID and selective cyclooxygenase (COX)-1 and COX-2 inhibitors in healing of chronic gastric ulcers

Hematological and Biochemical Effects Associated with Prolonged Administration of the NSAID Firocoxib in Adult Healthy Horses

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most commonly used classes of drugs in both human and veterinary medicine. However, many clinical side effects have been observed, especially when treatment has been prolonged. While the anti-inflammatory efficacy and safety of repeated administration of firocoxib (Previcox®), which is a selective NSAID COX-2 inhibitor, has been evaluated for short-term use (one to fourteen days), its clinical relevance for longer-term use is not known. As a preliminary study, healthy, adult male and female horses (n = 7) were treated with firocoxib for 40 days concomitant with the collection of blood samples encompassing treatment to assess hematological and biochemical endpoints. Daily oral administration of firocoxib was performed with one 57 mg tablet/animal (0.11-0.14 mg/kg), which was crushed and mixed with feed. Blood samples were collected one day before treatment (D0 or basal sample), during (D10, D20, D30, and D40), and after treatment (D55 and D70). Results indicated some hematological and biochemical effects were significantly reduced (p < 0.05) towards the end of treatment on D40 relative to pre-treatment or baseline values on D0. Post-treatment, all values returned to pre-treatment values within 30 days without any apparent clinical adversities. In conclusion, while these preliminary results are favorable for prolonged use of firocoxib in horses, future studies are required to evaluate the efficacy of prolonged use accompanied with other clinically relevant endpoints in healthy as well as injured or diseased animals.

Transport of Non-Steroidal Anti-Inflammatory Drugs across an Oral Mucosa Epithelium In Vitro Model

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most prescribed drugs to treat pain or fever. However, oral administration of NSAIDs is frequently associated with adverse effects due to their inhibitory effect on the constitutively expressed cyclooxygenase enzyme 1 (COX-1) in, for instance, the gastrointestinal tract. A systemic delivery, such as a buccal delivery, of NSAIDs would be beneficial and additionally has the advantage of a non-invasive administration route, especially favourable for children or the elderly. To investigate the transport of NSAIDs across the buccal mucosa and determine their potential for buccal therapeutic usage, celecoxib, diclofenac, ibuprofen and piroxicam were tested using an established oral mucosa Transwell® model based on human cell line TR146. Carboxyfluorescein and diazepam were applied as internal paracellular and transcellular marker molecule, respectively. Calculated permeability coefficients revealed a transport ranking of ibuprofen > piroxicam > diclofenac > celecoxib. Transporter protein inhibitor verapamil increased the permeability for ibuprofen, piroxicam and celecoxib, whereas probenecid increased the permeability for all tested NSAIDs. Furthermore, influence of local inflammation of the buccal mucosa on the transport of NSAIDs was mimicked by treating cells with a cytokine mixture of TNF-α, IL-1ß and IFN-γ followed by transport studies with ibuprofen (+ probenecid). Cellular response to pro-inflammatory stimuli was confirmed by upregulation of cytokine targets at the mRNA level, increased secreted cytokine levels and a significant decrease in the paracellular barrier. Permeability of ibuprofen was increased across cell layers treated with cytokines, while addition of probenecid increased permeability of ibuprofen in controls, but not across cell layers treated with cytokines. In summary, the suitability of the in vitro oral mucosa model to measure NSAID transport rankings was demonstrated, and the involvement of transporter proteins was confirmed; an inflammation model was established, and increased NSAID transport upon inflammation was measured.

Melatonin protects against ketorolac induced gastric mucosal toxic injuries through molecular mechanism associated with the modulation of Arylakylamine N-Acetyltransferase (AANAT) activity

Ketorolac tromethamine (KT), is a widely used non-steroidal anti-inflammatory drug (NSAID) for treating moderate to severe pain. However, the use of KT has been restricted due to its highly toxic attributes that lead to severe gastric ulceration and bleeding. The protective effects of exogenous melatonin (MT) has been reported in conditions associated with gastro-intestinal disorders. This study aims at exploring the role of gastric endogenous MT level and it's metabolizing enzyme AANAT, at the onset of ketorolac mediated toxicities in the gastric mucosa. Gastric mucosal damage was induced in experimental rats by oral administration of graded doses of KT, where 50 mg/kg b.w. of KT was observed to incur maximum gastric lesions. However, gastric damages were found to be protected in rats, pre-treated with 60 mg/kg b.w. of MT. Post-sacrifice, mean ulcer index, oxidative status, total melatonin levels and enzyme activities associated with MT biosynthesis and catabolism were estimated. The results reveal that KT decreases AANAT activity with a concomitant decline in endogenous MT level which cumulatively aggravates gastric toxicity. Moreover, exogenous MT administration has been found to be protective in ameliorating this ulcerogenic process in rats, challenged with KT. Biochemical and histo-pathological observations revealed the reduction in oxidative stress level and replenishment of depleted gastric MT levels in MT pre-treated animals, which might be the causative factors in conferring protection to the gastric tissues and residing mitochondria. The results revealed a correlation between depleted gastric MT level and ulcer formation, which unveiled a novel ulcerogenic mechanism. This may bring forth future therapeutic relevance for treating patients suffering from KT mediated acute gastric toxicities.

Aceclofenac-Loaded Microspheres Prepared by Vesicular Ionotropic Gelation to Minimize Drug-induced Gastric Ulcers in Rats

BACKGROUND

Aceclofenac is a non-steroidal anti-inflammatory drug and a potent analgesic. However, its oral ingestion may cause gastrointestinal problems, including dyspepsia, abnormal pain, nausea, diarrhea, and ulcerative colitis.

OBJECTIVE

Preparation of vesicular-based enteric microspheres containing aceclofenac by ionotropic gelation technique to minimize gastric irritation in rats.

METHODS

The micron-size vesicles were prepared by the ionic-orifice gelation method. Three types of vesicular-based microcapsules containing aceclofenac were prepared by employing sodium alginate as the coating material in combination with Eudragit L100, Eudragit S100, and polyvinylpyrrolidone PVP K90. The drug to sodium alginate to polymer ratios were 1:0.5:0.5, 1:1:1, and 1:1.5:1.5, respectively. Gelation of sodium alginate was induced by the dropwise addition of calcium chloride solution (10% w/v). Aceclofenac-loaded microspheres were evaluated in terms of aceclofenac content and in vitro drug release, and FTIR, DSC, and XRD were used for physicochemical evaluation of some selected formulae. The effects of microencapsulation on aceclofenac-induced ulcerative activity in male Wistar rats were also investigated.

RESULTS

The results indicated no interaction between aceclofenac and microcapsules forming polymers. In addition, microcapsules formulations M1, M4, and M7 gave maximal protection in acidic pH and optimal release in alkaline pH. The histopathological studies revealed that the reduction of ulceration is evident from the macroscopic and microscopic studies, which showed complete protection of the tissue morphology with no ulcers, indicating the effectiveness of the microcapsules system against aceclofenac-induced gastric ulceration in rats again.

CONCLUSION

Ionotropic gelation seems to be a simple, efficient technique to prepare aceclofenac-loaded microspheres with a reduced risk of gastric ulceration. It is possible to overcome the problem of gastric damage while utilizing aceclofenac by avoiding the exposure of the drug to the ulcer-prone area of the gastrointestinal tract.

A Review on the Application of Zeolites and Mesoporous Silica Materials in the Removal of Non-Steroidal Anti-Inflammatory Drugs and Antibiotics from Water

Zeolites and mesoporous silica materials are effective adsorbents that can be useful for the removal of various pharmaceuticals including non-steroidal anti-inflammatory drugs and antibiotics from low-quality water. This paper summarizes the properties and basic characteristics of zeolites and mesoporous silica materials and reviews the recent studies on the efficacy of the adsorption of selected non-steroidal medicinal products and antibiotics by these adsorbents to assess the potential opportunities and challenges of using them in water treatment. It was found that the adsorption capacity of sorbents with high silica content is related to their surface hydrophobicity (hydrophilicity) and structural features, such as micropore volume and pore size, as well as the properties of the studied medicinal products. This review can be of help to scientists to develop an effective strategy for reducing the amount of these two groups of pharmaceuticals in wastewater.

Ameliorative effect of Boesenbergin A, a chalcone isolated from Boesenbergia rotunda (Fingerroot) on oxidative stress and inflammation in ethanol-induced gastric ulcer in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Boesenbergia rotunda (L.) Mansf. Kulturpfl., previously known as Boesenbergia pandurata (Family: Zingiberaceae) is a ginger species, locally known as fingerroot. It is an integral part of Southeast Asian traditional medicine in alleviating many gastrointestinal disorders such as flatulence, carminative, stomach ache, dyspepsia, and peptic ulcer.

AIM OF THE STUDY

Earlier we have investigated the cytoprotective effect of Boesenbergia rotunda extract. In the present study, we investigated the gastroprotection activity of Boesenbergin A (BA), a chalcone isolated from Boesenbergia rotunda extract in ethanol-induced ulcer model in rats. Besides, the contribution of anti-inflammatory and anti-oxidant ability of BA as probable mechanisms involved in the anti-ulcer activity, also been studied.

MATERIALS AND METHODS

BA was orally administered in rats before ulcer induction with ethanol. The lesions of the gastric mucosa were evaluated macroscopically and histopathologically. The efficiency of BA in mucus production, NO production, PGE₂ synthesis, mucosal nonprotein sulphydryls, glutathione (GSH) level, and lipid peroxidation (MDA) level were studied. The involvement of the anti-inflammatory capacity of BA was analyzed by using the measurement of cytokines such as TNF-α and IL-6. Finally, the expression of biomarkers such as HSP 70 and iNOS was analyzed at the transcriptional and translational levels.

RESULTS

We confirmed the protective capacity of BA via the reduction of ulcerated and haemorrhagic areas. It has induced the protection through lowering GSH, MDA and increased NP-SH level. The plasma NO levels were significantly less in BA treated rats. Both cytokines TNF-α and IL-6 were decreased together with elevated PGE₂. Upregulation of HSP and downregulation of iNOS were determined in immunohistochemical and gene expression studies CONCLUSIONS: The current results suggest that the prophylactic effect found with BA is due to (i) boosting of gastric mucus production and suppression of inflammatory mediators, via pro-inflammatory cytokines and (ii) modulating the oxidative stress response. The usefulness of Boesenbergia rotunda in folk medicine in treating ulcers partially could be due to the presence of this chalcone.

Periovulatory administration of firocoxib did not alter ovulation rates and mitigated post-breeding inflammatory response in mares

Non-steroidal anti-inflammatory drugs (NSAIDs) are a therapeutic option for the treatment of inflammation. However, negative effects of non-selective NSAIDs for treatment of mares with endometritis have been described, including delayed uterine clearance and impairment of ovulations. Firocoxib is a specific cyclooxygenase-2 (COX-2) inhibitor and has the ability to act in the uterus of mares. We investigated the effects of firocoxib on ovulation rate, numbers of polymorphonuclear neutrophils (PMNs), and COX-2 protein levels in the endometrial tissue of susceptible mares after insemination. Two experiments were conducted. In experiment 1, twenty mares were evaluated in two consecutive estrous cycles broken into the following groups: Control - no pharmacological interference; Treatment - mares were treated with 0.2 mg/kg of firocoxib orally. The treatment began on the day of ovulation induction, and firocoxib was administered until one day after artificial insemination (AI). Ovulation was induced with 1 mg of deslorelin acetate and the mares were inseminated 24 h after the injection. Ovulation was confirmed 48 h after induction, and embryos were collected eight days after ovulation. Experiment 2: Nine mares susceptible to persistent mating-induced endometritis (PMIE) were artificially inseminated. The mares were examined with ultrasound and inseminated with fresh semen in two consecutive cycles, control and treated, in a cross-over study design. The amount of intrauterine fluid was measured, and endometrial samples were collected 24 h after AI. The number of PMNs was determined by endometrial cytology and biopsy, and COX-2 labeling in endometrial samples was evaluated by immunohistochemistry. Firocoxib treatment did not induce ovulatory failure or affect embryo recovery rate in Experiment 1. In Experiment 2, firocoxib treatment reduced inflammation after AI in mares as evidenced with results regarding PMN numbers/percentage and endometrial COX-2 staining. In conclusion, the proposed treatment with firocoxib reduced endometrial inflammation in mares susceptible to PMIE after breeding, with no adverse effects.

(-)-Myrtenol accelerates healing of acetic acid-induced gastric ulcers in rats and in human gastric adenocarcinoma cells

The gastroprotective property of (-)-myrtenol, a monoterpenoid, has been demonstrated previously against acute gastric ulceration induced by ethanol. However, the healing property of (-)-myrtenol in a chronic gastric ulcer model remains to be verified. This study evaluated its healing efficacy and the mechanism involved using the rat model of chronic gastric ulcer induced by serosal injection of 80% acetic acid in vivo, and human gastric adenocarcinoma cells (AGS) in vitro. The results showed that compared to vehicle-treated ulcer controls, oral administration of (-)-myrtenol (50 and 100 mg/kg/day) for 7 days promoted ulcer healing, as indicated by significant decreases in ulcer area and volume. The macroscopic and microscopic findings confirmed the healing potential of (-)-myrtenol. The ulcer healing activity was also associated with significant increases in gastric mucin content, collagen deposition, number of cells with positive marking for proliferating cell nuclear antigen (PCNA), and by changes in the expression of the inflammatory parameters tumor necrosis factor (TNF)-α, interleukin (IL)-1β and cyclooxygenase (COX)-2, as well as a decrease of metalloproteinases (MMP-9 and MMP-2) activity. Furthermore, in vitro assays using the AGS cultures revealed that (-)-myrtenol favors wound healing activity via stimulation of cell proliferation and migration without altering the cell viability. Taken together, these findings indicate that (-)-myrtenol has gastro-cytoprotective and ulcer healing properties that can be further explored to develop a new therapeutic agent from a natural source for the treatment of gastric ulcer.

Sex-specific effects of Eugenia punicifolia extract on gastric ulcer healing in rats

AIM

To evaluate the sex-specific effects of a hydroalcoholic extract from Eugenia punicifolia (HEEP) leaves on gastric ulcer healing.

METHODS

In this rat study involving males, intact (cycling) females, and ovariectomized females, gastric ulcers were induced using acetic acid. A vehicle, lansoprazole, or HEEP was administered for 14 d after ulcer induction. Body weight was monitored throughout the treatment period. At the end of treatment, the rats were euthanized and the following in vivo and in vitro investigations were performed: macroscopic examination of the lesion area and organ weights, biochemical analysis, zymography, and evaluation of protein expression levels. Additionally, the concentration-dependent effect of HEEP was evaluated in terms of subacute toxicity and cytotoxicity.

RESULTS

Compared to the vehicle, HEEP demonstrated a great healing capacity by substantially reducing the ulcerative lesion area in males (52.44%), intact females (85.22%), and ovariectomized females (65.47%), confirming that HEEP accelerates the healing of acetic acid-induced gastric lesions and suggesting that this effect is modulated by female sex hormones. The antiulcer effect of HEEP was mediated by prostaglandin E₂ only in male rats. Overall, the beneficial effect of HEEP was the highest in intact females. Notably, HEEP promoted the expression of vascular endothelial growth factor (intact vs ovariectomized females) and decreased the expression of Caspase-8 and Bcl-2 (intact female vs male or ovariectomized female). Additionally, HEEP enhanced fibroblast proliferation and migration into a wounded area in vitro, confirming its healing effect. Finally, no sign of subacute toxicity or cytotoxicity of HEEP was observed.

CONCLUSION

In gastric ulcers, HEEP-induced healing (modulated by female sex hormones; in males, mediated by prostaglandin) involves extracellular matrix remodeling, with gastric mucosa cell proliferation and migration.

Raging the War Against Inflammation With Natural Products

Over the last few decade Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are the drugs of choice for treating numerous inflammatory diseases including rheumatoid arthritis. The NSAIDs produces anti-inflammatory activity via inhibiting cyclooxygenase enzyme, responsible for the conversation of arachidonic acid to prostaglandins. Likewise, cyclooxegenase-2 inhibitors (COX-2) selectively inhibit the COX-2 enzyme and produces significant anti-inflammatory, analgesic, and anti-pyretic activity without producing COX-1 associated gastrointestinal and renal side effects. In last two decades numerous selective COX-2 inhibitors (COXIBs) have been developed and approved for various inflammatory conditions. However, data from clinical trials have suggested that the prolong use of COX-2 inhibitors are also associated with life threatening cardiovascular side effects including ischemic heart failure and myocardial infection. In these scenario secondary metabolites from natural product offers a great hope for the development of novel anti-inflammatory compounds. Although majority of the natural product based compounds exhibit more selectively toward COX-1. However, the data suggest that slight structural modification can be helpful in developing COX-2 selective secondary metabolites with comparative efficacy and limited side effects. This review is an effort to highlight the secondary metabolites from terrestrial and marine source with significant COX-2 and COX-2 mediated PGE2 inhibitory activity, since it is anticipated that isolates with ability to inhibit COX-2 mediated PGE2 production would be useful in suppressing the inflammation and its classical sign and symptoms. Moreover, this review has highlighted the potential lead compounds including berberine, kaurenoic acid, α-cyperone, curcumin, and zedoarondiol for further development with the help of structure-activity relationship (SAR) studies and their current status.

Mechanisms of curcumin-induced gastroprotection against ethanol-induced gastric mucosal lesions

BACKGROUND

Curcumin, a pleiotropic substance used for centuries in traditional medicine, exhibits antioxidant, anti-inflammatory and antiproliferative efficacy against various tumours, but the role of curcumin in gastroprotection is little studied. We determined the effect of curcumin against gastric haemorrhagic lesions induced by 75% ethanol and alterations in gastric blood flow (GBF) in rats with cyclooxygenase-1 (COX-1) and COX-2 activity inhibited by indomethacin, SC-560 or rofecoxib, inhibited NO-synthase activity, capsaicin denervation and blockade of TRPV1 receptors by capsazepine.

METHODS

One hour after ethanol administration, the gastric mucosal lesions were assessed by planimetry, the GBF was examined by H2 gas clearance, plasma gastrin was determined by radioimmunoassay, and the gastric mucosal mRNA expression of Cdx-2, HIF-1α, HO-1 and SOD 2 was analysed by RT-PCR.

RESULTS

Curcumin, in a dose-dependent manner, reduced ethanol-induced gastric lesions and significantly increased GBF and plasma gastrin levels. Curcumin-induced protection was completely reversed by indomethacin and SC-560, and significantly attenuated by rofecoxib, L-NNA, capsaicin denervation and capsazepine. Curcumin downregulated Cdx-2 and Hif-1α mRNA expression and upregulated HO-1 and SOD 2, and these effects were reversed by L-NNA and further restored by co-treatment of L-NNA with L-arginine.

CONCLUSIONS

Curcumin-induced protection against ethanol damage involves endogenous PG, NO, gastrin and CGRP released from sensory nerves due to activation of the vanilloid TRPV1 receptor. This protective effect can be attributed to the inhibition of HIF-1α and Cdx-2 expression and the activation of HO-1 and SOD 2 expression.

Healing and Antisecretory Effects of Aqueous Extract of Eremomastax speciosa (Acanthaceae) on Unhealed Gastric Ulcers

OBJECTIVE

This work investigated the healing and antisecretory effects of the aqueous extract of Eremomastax speciosa on "unhealed gastric ulcers" associated with gastric acid hypersecretion.

MATERIALS AND METHODS

"Unhealed gastric ulcers" were induced using indomethacin following the establishment of acetic-acid-induced chronic gastric ulcers. The extract (200 and 400 mg/kg, per os) was administered concomitantly with indomethacin (1 mg/kg, subcutaneously). The effects of the extract on both basal and histamine-stimulated gastric acid secretion were determined. Mucus secretion and oxidative stress parameters were measured, and histological assessment of ulcer healing was carried out.

RESULTS

The extract significantly promoted the healing process in rats subjected to "unhealed gastric ulcers" (82.4-88.5% healing rates). Treatment with the extract significantly reduced the basal (25.95-49.51% reduction rates) and histamine-stimulated (24.25-47.41%) acid secretions. The healing effect of the extract was associated with a significant (p < 0.05) increase of mucus secretion and concentrations of antioxidant enzymes compared with the controls. The extract at the highest dose showed normalization of the mucosa, without glandular destruction and with the disappearance of fibrosis and lymphocyte infiltration.

CONCLUSION

The abilities of the extract to increase mucus secretion, to reinforce antioxidant status, and to inhibit acid secretion would be some of the mechanisms by which this extract would accelerate the healing process in "unhealed gastric ulcers."

trans-4,4'-Dihydroxystilbene (DHS) inhibits human neuroblastoma tumor growth and induces mitochondrial and lysosomal damages in neuroblastoma cell lines

In view of the inadequacy of neuroblastoma treatment, five hydroxystilbenes and resveratrol (Resv) were screened for their cytotoxic property against human neuroblastoma cell lines. The mechanism of cytotoxic action of the most potent compound, trans-4,4'-dihydroxystilbene (DHS) was investigated in vitro using human neuroblastoma cell lines. DHS was also tested in a mouse xenograft model of human neuroblastoma tumor. The MTT, sub-G1, annexin V and clonogenic assays as well as microscopy established higher cytotoxicity of DHS than Resv to the IMR32 cell line. DHS (20 μM) induced mitochondrial membrane permeabilization (MMP) in the cells, as revealed from JC-1 staining, cytochrome c and ApaF1 release and caspases-9/3 activation. DHS also induced lysosomal membrane permeabilization (LMP) to release cathepsins B, L and D, and the cathepsins inhibitors partially reduced MMP/caspase-3 activation. The ROS, produced by DHS activated the p38 and JNK MAPKs to augment the BAX activity and BID-cleavage, and induce LMP and MMP in the cells. DHS (100 mg/kg) also inhibited human neuroblastoma tumor growth in SCID mice by 51%. Hence, DHS may be a potential chemotherapeutic option against neuroblastoma. The involvement of an independent LMP as well as a partially LMP-dependent MMP by DHS is attractive as it provides options to target both mitochondria and lysosome.

Suppression of calpain expression by NSAIDs is associated with inhibition of cell migration in rat duodenum

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for the alleviation of pain and inflammation, but these drugs are also associated with a suite of negative side effects. Gastrointestinal (GI) toxicity is particularly concerning since it affects an estimated 70% of individuals taking NSAIDs routinely, and evidence suggests the majority of toxicity is occurring in the small intestine. Traditionally, NSAID-induced GI toxicity has been associated with indiscriminate inhibition of cyclooxygenase isoforms, but other mechanisms, including inhibition of cell migration, intestinal restitution, and wound healing, are likely to contribute to toxicity. Previous efforts demonstrated that treatment of cultured intestinal epithelial cells (IEC) with NSAIDs inhibits expression and activity of calpain proteases, but the effects of specific inhibition of calpain expression in vitro or the effects of NSAIDs on intestinal cell migration in vivo remain to be determined. Accordingly, we examined the effect of suppression of calpain protease expression with siRNA on cell migration in cultured IECs and evaluated the effects of NSAID treatment on epithelial cell migration and calpain protease expression in rat duodenum. Our results show that calpain siRNA inhibits protease expression and slows migration in cultured IECs. Additionally, NSAID treatment of rats slowed migration up the villus axis and suppressed calpain expression in duodenal epithelial cells. Our results are supportive of the hypothesis that suppression of calpain expression leading to slowing of cell migration is a potential mechanism through which NSAIDs cause GI toxicity.

Potentiation of indomethacin-induced anti-inflammatory response by pioglitazone in carrageenan-induced acute inflammation in rats: Role of PPARγ receptors

This study aimed to assess the interaction between anti-inflammatory effects of pioglitazone (peroxysome proliferator activated receptor-gamma (PPARγ) agonist, PGL), and indomethacin (cyclooxygenase (COX) inhibitor, IND) and to evaluate the possible underlying mechanisms. Paw edema induced by carrageenan was used to induce inflammation. Different doses of IND (0.3-10mg/kg) and PGL (1-20mg/kg) alone or in combination were administered intraperitoneally to rats. Paw tissue levels of PPARγ, COX-2, and prostaglandin E2 and serum levels of TNF-α and IL-10 were also estimated. Doses of IND and PGL showed a statistically significant anti-inflammatory effect. Combination of a non-effective dose of IND (0.3mg/kg) with increasing doses of PGL (1-10mg/kg) resulted in potentiated anti-inflammation and vise versa. IND, PGL and the combination were able to reduce the COX-2, PGE2 contents and TNF-α level. Moreover, all these treatments caused elevation in PPARγ levels and IL-10 levels. However, when the rats were pre-treated with GW-9662 (a selective PPARγ antagonist), all the anti-inflammation and alterations in the biochemical factors were antagonized. These results showed that PGL markedly enhanced the anti-inflammatory activity of IND and this effect mediated partly at least, through PPARγ. Possible mechanisms of the interaction were that PGL stimulates the PPARγ and inhibits COX-2 by those cytokines that trigger the PPARγ and also inhibit COX-2. This study suggests that combination therapy with pioglitazone and indomethacin may provide an alternative for the clinical control of inflammation especially in patients with diabetes.

Protective effect of trillin against ethanol-induced acute gastric lesions in an animal model

The purpose of the present study was to evaluate gastroprotective effect of trillin on mucosal lesions induced by ethanol.

Protective Effects of Manassantin A against Ethanol-Induced Gastric Injury in Rats

Manassantin A, a neolignan isolated from Saururus chinensis, is a major phytochemical compound that has various biological activities, including anti-inflammatory, neuroleptic, and human acyl-CoA : cholesterol acyltransferase (ACAT) inhibitory activities. In this study, we investigated the protective effects of manassantin A against ethanol-induced acute gastric injury in rats. Gastric injury was induced by intragastric administration of 5 mL/kg body weight of absolute ethanol to each rat. The positive control group and the manassantin A group were given oral doses of omeprazole (20 mg/kg) or manassantin A (15 mg/kg), respectively, 1 h prior to the administration of absolute ethanol. Our examinations revealed that manassantin A pretreatment reduced ethanol-induced hemorrhage, hyperemia, and epithelial cell loss in the gastric mucosa. Manassantin A pretreatment also attenuated the increased lipid peroxidation associated with ethanol-induced acute gastric lesions, increased the mucosal glutathione (GSH) content, and enhanced the activities of antioxidant enzymes. The levels of pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β were clearly decreased in the manassantin A-pretreated group. In addition, manassantin A pretreatment enhanced the levels of cyclooxygenase (COX)-1, COX-2, and prostaglandin E2 (PGE2) and reduced the inducible nitric oxide synthase (iNOS) overproduction and nuclear factor kappa B (NF-κB) phosphorylation. Collectively, these results indicate that manassantin A protects the gastric mucosa from ethanol-induced acute gastric injury, and suggest that these protective effects might be associated with COX/PGE2 stimulation, inhibition of iNOS production and NF-κB activation, and improvements in the antioxidant and anti-inflammatory status.

Inhibition of Kv channel expression by NSAIDs depolarizes membrane potential and inhibits cell migration by disrupting calpain signaling

Clinical use of non-steroidal anti-inflammatory drugs (NSAIDs) is well known to cause gastrointestinal ulcer formation via several mechanisms that include inhibiting epithelial cell migration and mucosal restitution. The drug-affected signaling pathways that contribute to inhibition of migration by NSAIDs are poorly understood, though previous studies have shown that NSAIDs depolarize membrane potential and suppress expression of calpain proteases and voltage-gated potassium (Kv) channel subunits. Kv channels play significant roles in cell migration and are targets of NSAID activity in white blood cells, but the specific functional effects of NSAID-induced changes in Kv channel expression, particularly on cell migration, are unknown in intestinal epithelial cells. Accordingly, we investigated the effects of NSAIDs on expression of Kv1.3, 1.4, and 1.6 in vitro and/or in vivo and evaluated the functional significance of loss of Kv subunit expression. Indomethacin or NS-398 reduced total and plasma membrane protein expression of Kv1.3 in cultured intestinal epithelial cells (IEC-6). Additionally, depolarization of membrane potential with margatoxin (MgTx), 40mM K(+), or silencing of Kv channel expression with siRNA significantly reduced IEC-6 cell migration and disrupted calpain activity. Furthermore, in rat small intestinal epithelia, indomethacin and NS-398 had significant, yet distinct, effects on gene and protein expression of Kv1.3, 1.4, or 1.6, suggesting that these may be clinically relevant targets. Our results show that inhibition of epithelial cell migration by NSAIDs is associated with decreased expression of Kv channel subunits, and provide a mechanism through which NSAIDs inhibit cell migration and may contribute to NSAID-induced gastrointestinal (GI) toxicity.

Model-based prediction of the acute and long-term safety profile of naproxen in rats

BACKGROUND AND PURPOSE

Despite the increasing importance of biomarkers as predictors of drug effects, toxicology protocols continue to rely on the experimental evidence of adverse events (AEs) as a basis for establishing the link between indicators of safety and drug exposure. Furthermore, biomarkers may facilitate the translation of findings from animals to humans. Combined with a model-based approach, biomarker data have the potential to predict long-term effects arising from prolonged drug exposure. Here, we used naproxen as a paradigm to explore the feasibility of a biomarker-guided approach for the prediction of long-term AEs in humans.

EXPERIMENTAL APPROACH

An experimental toxicology protocol was set up for evaluating the effects of naproxen in rats, in which four active doses were tested (7.5, 15, 40 and 80 mg·kg(-1) ). In addition to AE monitoring and histology, a few blood samples were also collected for the assessment of drug exposure, TXB2 and PGE2 levels. Non-linear mixed effects modelling was used to analyse the data and identify covariate factors on the incidence and severity of AEs.

KEY RESULTS

Modelling results showed that besides drug exposure, maximum PGE2 inhibition and treatment duration were also predictors of gastrointestinal ulceration. Although PGE2 levels were clearly linked to the incidence rates, it appeared that ulceration severity is better predicted by measures of drug exposure.

CONCLUSIONS AND IMPLICATIONS

These results show that the use of a model-based approach provides the opportunity to integrate pharmacokinetics, pharmacodynamics and toxicity data, enabling optimization of the design, analysis and interpretation of toxicology experiments.

Endogenous prostaglandins and afferent sensory nerves in gastroprotective effect of hydrogen sulfide against stress-induced gastric lesions

Hydrogen sulfide (H₂S) plays an important role in human physiology, exerting vasodilatory, neuromodulatory and anti-inflammatory effects. H₂S has been implicated in the mechanism of gastrointestinal integrity but whether this gaseous mediator can affect hemorrhagic lesions induced by stress has been little elucidated. We studied the effect of the H₂S precursor L-cysteine, H₂S-donor NaHS, the H₂S synthesizing enzyme (CSE) activity inhibitor- D,L-propargylglycine (PAG) and the gastric H₂S production by CSE/CBS/3-MST activity in water immersion and restraint stress (WRS) ulcerogenesis and the accompanying changes in gastric blood flow (GBF). The role of endogenous prostaglandins (PGs) and sensory afferent nerves releasing calcitonin gene-related peptide (CGRP) in the mechanism of gastroprotection induced by H₂S was examined in capsaicin-denervated rats and those pretreated with capsazepine to inhibit activity of vanilloid receptors (VR-1). Rats were pretreated with vehicle, NaHS, the donor of H₂S and or L-cysteine, the H₂S precursor, with or without the concurrent treatment with 1) nonselective (indomethacin) and selective cyclooxygenase (COX)-1 (SC-560) or COX-2 (rofecoxib) inhibitors. The expression of mRNA and protein for COX-1 and COX-2 were analyzed in gastric mucosa pretreated with NaHS with or without PAG. Both NaHS and L-cysteine dose-dependently attenuated severity of WRS-induced gastric lesions and significantly increased GBF. These effects were significantly reduced by pretreatment with PAG and capsaicin denervation. NaHS increased gastric H₂S production via CSE/CBS but not 3-MST activity. Inhibition of COX-1 and COX-2 activity significantly diminished NaHS- and L-cysteine-induced protection and hyperemia. NaHS increased expression of COX-1, COX-2 mRNAs and proteins and raised CGRP mRNA expression. These effects of NaHS on COX-1 and COX-2 protein contents were reversed by PAG and capsaicin denervation. We conclude that H₂S exerts gastroprotection against WRS-induced gastric lesions by the mechanism involving enhancement in gastric microcirculation mediated by endogenous PGs, sensory afferent nerves releasing CGRP and the activation of VR-1 receptors.

Gastroprotective activity of violacein isolated from Chromobacterium violaceum on indomethacin-induced gastric lesions in rats: investigation of potential mechanisms of action

Chromobacterium violaceum, Gram-negative bacteria species found in tropical regions of the world, produces a distinct deep violet-colored pigment called violacein. In the present study, we investigated whether violacein can promote a gastroprotective effect and verified the possible mechanisms involved in this action. For this study, an indomethacin-induced gastric ulcer rat model was used. The roles of biomolecules such as MPO, PGE₂, pro- and anti-inflammatory cytokines, growth factors, caspase-3, NO, K⁺ATP channels, and α₂-receptors were investigated. Violacein exhibited significant gastroprotective effect against indomethacin-induced lesions, while pretreatment with L-NAME and glibenclamide (but not with NEM or yohimbine) was able to reverse this action. Pretreatment with violacein also restored cNOS level to normal and led to attenuation of enhanced apoptosis and gastric microvascular permeability. Our results suggest that violacein provides a significant gastroprotective effect in an indomethacin-induced ulcer model through the maintenance of some vital protein molecules, and this effect appears to be mediated, at least in part, by endogenous prostaglandins, NOS, K⁺ATP channel opening, and inhibition of apoptosis and gastric microvascular permeability.

Evaluation of the reproductive toxicity of naproxen sodium and meloxicam in male rats

Nonsteroidal anti-inflammatory drugs that are cyclooxygenase (COX) enzyme inhibitors have generally been used in short-term pain management and also to treat inflammation chronically. It is known that COX enzyme and prostaglandins play important roles in the regulation of reproductive functions in females. However, there are relatively few studies for the male reproductive system, and the results of these studies are contradictory. In this study, sperm count and motility, COX-1, COX-2, prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), and prostaglandin F2α (PGF2α) levels in testis tissue, plasma follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels, and histopathological examination of testis tissue were evaluated after naproxen sodium and meloxicam administration in male rats. Also, testis superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione (GSH) levels were measured to investigate the oxidation status. According to our results, sperm count and motility were significantly decreased in treatment groups. Plasma hormone levels did not show any statistical differences between the groups. COX-1, PGE2, and PGF2α levels were significantly decreased, while the decreases in COX-2 and PGE1 levels did not show any significance statistically. Testis SOD, catalase, GPx, and GSH levels were decreased significantly. According to the results of histopathological examination, damage in seminiferous tubules, where spermatogenesis developed, was observed. In conclusion, naproxen sodium and meloxicam decreased the sperm count and motility and also induced the damage of seminiferous tubules as a direct effect without affecting plasma hormone levels in our study. The mechanism of the reproductive toxicity induced by these agents may be based on the inhibition of prostaglandin synthesis and the induction of oxidative stress can be emphasized as a secondary factor.

New satiety hormone nesfatin-1 protects gastric mucosa against stress-induced injury: mechanistic roles of prostaglandins, nitric oxide, sensory nerves and vanilloid receptors

Nesfatin-1 belongs to a family of anorexigenic peptides, which are responsible for satiety and are identified in the neurons and endocrine cells within the gut. These peptides have been implicated in the control of food intake; however, very little is known concerning its contribution to gastric secretion and gastric mucosal integrity. In this study the effects of nesfatin-1 on gastric secretion and gastric lesions induced in rats by 3.5h of water immersion and restraint stress (WRS) were determined. Exogenous nesfatin-1 (5-40μg/kg i.p.) significantly decreased gastric acid secretion and attenuated gastric lesions induced by WRS, and this was accompanied by a significant rise in plasma NUCB2/nefatin-1 levels, the gastric mucosal blood flow (GBF), luminal NO concentration, generation of PGE2 in the gastric mucosa, an overexpression of mRNA for NUBC2 and cNOS, as well as a suppression of iNOS and proinflammatory cytokine IL-1β and TNF-α mRNAs. Nesfatin-1-induced protection was attenuated by suppression of COX-1 and COX-2 activity, the inhibition of NOS with L-NNA, the deactivation of afferent nerves with neurotoxic doses of capsaicin, and the pretreatment with capsazepine to inhibit vanilloid VR1 receptors. This study shows for the first time that nesfatin-1 exerts a potent protective action in the stomach of rats exposed to WRS and these effects depend upon decrease in gastric secretion, hyperemia mediated by COX-PG and NOS-NO systems, the activation of vagal and sensory nerves and vanilloid receptors.

Roles of pro-angiogenic and anti-angiogenic factors as well as matrix metalloproteinases in healing of NSAID-induced small intestinal ulcers in rats

AIMS

We examined changes in the expression of a pro-angiogenic factor, vascular endothelial growth factor (VEGF), and an anti-angiogenic factor, endostatin, as well as matrix metalloproteinase (MMP)-2 and MMP-9 in the rat small intestine after administration of indomethacin and investigated the roles of these factors in the healing of indomethacin-induced small intestinal ulcers.

MAIN METHODS

Male SD rats were given indomethacin (10mg/kg) p.o. and euthanized at various time points (3-24h and 2-7days) after the administration. To impair the healing of these lesions, low-dose of indomethacin (2mg/kg) was given p.o. once daily for 6days starting 1day after ulceration. Levels of VEGF, endostatin, MMP-2 and MMP-9 were determined by Western blotting.

KEY FINDINGS

The expression of both VEGF and endostatin was upregulated after the ulceration. Repeated administration of low-dose indomethacin impaired the ulcer healing with a decrease of VEGF expression and a further increase of endostatin expression, resulting in a marked decrease in the ratio of VEGF/endostatin expression. The levels of MMP-2 and MMP-9 were both significantly increased after the ulceration, but these responses were suppressed by the repeated indomethacin treatment. The healing of these ulcers was significantly delayed by the repeated administration of MMP inhibitors such as ARP-101 and SB-3CT.

SIGNIFICANCE

The results confirm the importance of the balance between pro-angiogenic and anti-angiogenic activities in the healing of indomethacin-induced small intestinal damage and further suggest that the increased expression of MMP-2 and MMP-9 is another important factor for ulcer healing in the small intestine.

Rebamipide helps defend against nonsteroidal anti-inflammatory drugs induced gastroenteropathy: a systematic review and meta-analysis

BACKGROUND

Gastrointestinal toxicity of nonsteroidal anti-inflammatory drugs (NSAIDs) has been perplexing most clinicians and users of NSAIDs. Rebamipide is increasingly advocated as a candidate option for the prevention of NSAIDs induced gastrointestinal mucosal injury.

AIMS

To assess the efficacy and the safety of rebamipide for the prevention and treatment of NSAID-induced gastroenteropathy.

METHODS

PubMed, Embase, Web of Science, Google Scholar, the Cochrane Library, Japan Science and Technology Information Aggregator, and China Biology Medicine Disc were searched up to December 2011. Randomized controlled trials (RCTs) recruiting subjects with co-prescriptions of NSAIDs and rebamipide were eligible. Efficacy and safety of rebamipide were reevaluated, and dichotomous data were pooled to obtain relative risk (RR) with a 95 % confidence interval. Heterogeneity and publication bias were assessed by the inconsistency index statistic and funnel plot analysis, respectively.

RESULTS

The search identified 338 citations, and 15 RCTs including 965 individuals were eligible. In general, rebamipide acted better than placebo against short-term NSAID-induced gastroduodenal injury. Separate studies showed rebamipide was equal to or not superior to traditional strategies (including PPIs, H2RA and misoprostol treatment). Especially, rebamipide showed a beneficial effect against the small bowel damage (total RR = 2.70, 95 % confidence interval = 1.02-7.16, P = 0.045) when compared with placebo group. The average incidence of adverse events was about 36.1 % (0-70.0 %) but no serious event was recorded.

CONCLUSIONS

Current evidences show rebamipide is effective and safe for defending against NSAID-induced gastroduodenal and lower-gastrointestinal injuries. However, more well-designed trials should be conducted to fully confirm the practical value of rebamipide.

Cost Effectiveness Associated with Helicobacter pylori Screening and Eradication in Patients Taking Nonsteroidal Anti-Inflammatory Drugs and/or Aspirin

BACKGROUND/AIMS

This study was performed to investigate the cost effectiveness of Helicobacter pylori screening/eradication in South Korean patients treated with nonsteroidal anti-inflammatory drugs (NSAIDs) and/or aspirin.

METHODS

A decision Markov model was used to estimate the effectiveness and economic impact of an H. pylori screening/eradication strategy compared to a no-screening strategy among patients who were included in the model at the age of 40 years. Utility weights were applied to four of the health status groups to reflect quality-adjusted life years (QALY). The costs of screening, H. pylori eradication, and managing peptic ulcer and ulcer complications were obtained from South Korea-specific data.

RESULTS

The total costs per patient were US $2,454 for the H. pylori screening/eradication and US $3,182 for the no-screening strategy. The QALYs for the two strategies were 16.05 and 15.73, respectively. The results were robust for the analyses of all different cohort groups who entered the model at the age of 30, 50, or 60 years and for NSAIDs-naïve patients. Through the probabilistic sensitivity analysis, the robustness of our study's results was also determined.

CONCLUSIONS

The H. pylori screening/eradication strategy was found to be less expensive and more effective compared to the no-screening strategy among South Korean patients taking NSAIDs and/or aspirin.

Evaluation of antiulcer activity of indole-3-carbinol and/or omeprazole on aspirin-induced gastric ulcer in rats

The present work is an attempt to elucidate the antiulcer activity of indole-3-carbinol (I3C), which is one of the anticarcinogenic phytochemicals found in the vegetables of Cruciferae family such as broccoli and cauliflower, alone or in combination with omeprazole (OMP), a proton pump inhibitor, to diminish the effects of induced acute gastric ulcer by aspirin (ASA) in male albino rats. A total of 48 adult male albino rats were used in the present study. Animals were divided into eight experimental groups (six animals each group). They were given different experimental inductions of ASA at a dose of 500 mg/kg/body weight, OMP at a dose of 20 mg/kg/body weight and I3C at a dose of 20 mg/kg/body weight either alone or in combination with each other orally for a duration of 7 days. Inner stomach features, ulcer index, pH activity, body weight, stomach weight, hematological investigations, serum total protein albumin and reduced glutathione activity  were investigated in addition to the histological, histochemical and immunohistochemical stain of cyclooxygenase-2 to the stomach tissue of normal control, ulcerated and treated ulcerated rats. The results of this study revealed that oral administration of ASA to rats produced the expected characteristic mucosal lesions. OMP accelerated ulcer healing but the administration of I3C either alone or in combination with OMP to ASA-ulcerated rats produced a profound protection to the gastric mucosa from injury induced by ASA. Our results suggested that administration of antiulcer natural substances such as I3C in combination with the perused treatment such as OMP is a very important initiative in the development of new strategies in ulcer healing.

Nitric oxide-releasing aspirin but not conventional aspirin improves healing of experimental colitis

AIM: To determine the effect of non-selective cyclooxygenase (COX) inhibitors, selective COX-2 inhibitors and nitric oxide (NO)-releasing aspirin in the healing of ulcerative colitis.

METHODS: Rats with 2,4,6 trinitrobenzenesulfon-ic acid (TNBS)-induced colitis received intragastric (ig) treatment with vehicle, aspirin (ASA) (a non-selective COX inhibitor), celecoxib (a selective COX-2 inhibitor) or NO-releasing ASA for a period of ten days. The area of colonic lesions, colonic blood flow (CBF), myeloperoxidase (MPO) activity and expression of proinflammatory markers COX-2, inducible form of nitric oxide synthase (iNOS), IL-1β and tumor necrosis factor (TNF)-α were assessed. The effects of glyceryl trinitrate (GTN), a NO donor, and 2-(4-carboxyphenyl)-4,5-dihydro-4,4,5,5-​tetramethyl-1H-imidazolyl-1-oxy-3-oxide, onopotassium salt (carboxy-PTIO), a NO scavenger, administered without and with ASA or NO-ASA, and the involvement of capsaicin-sensitive afferent nerves in the mechanism of healing the experimental colitis was also determined.

RESULTS: Rats with colitis developed macroscopic and microscopic colonic lesions accompanied by a significant decrease in the CBF, a significant rise in colonic weight, MPO activity and plasma IL-1β and TNF-α levels. These effects were aggravated by ASA and 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC-560), but not celecoxib and counteracted by concurrent treatment with a synthetic prostaglandin E₂ (PGE₂) analog. Treatment with NO-ASA dose-dependently accelerated colonic healing followed by a rise in plasma NO_x content and CBF, suppression of MPO and downregulation of COX-2, iNOS, IL-1β and TNF-α mRNAs. Treatment with GTN, the NO donor, significantly inhibited the ASA-induced colonic lesions and increased CBF, while carboxy-PTIO or capsaicin-denervation counteracted the NO-ASA-induced improvement of colonic healing and the accompanying increase in the CBF. These effects were restored by co-treatment with calcitonin gene related peptide (CGRP) and NO-ASA in capsaicin-denervated animals.

CONCLUSION: NO-releasing ASA, in contrast to ASA, COX-1 inhibitors, and SC-560, accelerated the healing of colitis via a mechanism involving NO mediated improvement of microcirculation and activation of sensory nerves releasing CGRP.

Role of the COX-independent pathways in the ulcer-healing action of epigallocatechin gallate

The modulation of the cyclooxygenase-independent pathway by the green tea-derived polyphenol, epigallocatechin gallate (EGCG) during its healing action against indomethacin (IND)-induced stomach ulceration in mice was investigated. On the 3rd day of its administration, IND (18 mg kg(-1)) induced maximum stomach ulceration which was associated with increased myeloperoxidase (MPO) activity (2.1-fold, p < 0.001), and inducible nitric oxide synthase (iNOS) expression (2.5-fold, p < 0.001), along with augmented levels of serum nitrite (1.3-fold, p < 0.001), selectins and cell adhesion molecules (CAMs), as well as reduced endothelial nitric oxide synthase (eNOS) expression (53%, p < 0.001). Treatment with EGCG (2 mg kg(-1)) and omeprazole (3 mg kg(-1)) for 3 days reversed these parameters, and provided excellent (76-77%) ulcer healing.

Resveratrol commonly displays hormesis: occurrence and biomedical significance

Resveratrol induces hormetic dose responses in a wide range of biological models, affecting numerous endpoints of biomedical and therapeutic significance. These responses were reported for numerous human tumor cell lines affecting breast, prostate, colon, lung, uterine and leukemia. In such cases, low concentrations of resveratrol enhanced tumor cell proliferation whereas higher concentrations were inhibitory. Similar resveratrol-induced biphasic dose responses were seen with several parasitic diseases, including Leishmaniasis and trichinella. Hormetic effects were also reported in animal models for cardiovascular induced injury, gastric lesions, ischemic stroke, Alzheimer's disease and osteoporosis. In these cases, there was often a protective effect at low doses but an adverse effect at higher doses, exacerbating the disease process/incidence. This analysis indicates that many effects induced by resveratrol are dependent on dose and that opposite effects occur at low and high doses, being indicative of a hormetic dose response. Despite consistent occurrence of hormetic dose responses of resveratrol in a wide range of biomedical models, epidemiologic and clinical trials are needed to assess the nature of its dose-response in humans.

Biphasic Effect of Phyllanthus emblica L. Extract on NSAID-Induced Ulcer: An Antioxidative Trail Weaved with Immunomodulatory Effect

Amla (Phyllanthus emblica L.), apart from its food value, can be used as a gastroprotective agent in non steroidal anti-inflammatory drug (NSAID)-induced gastropathy. It has been suggested that the antioxidative property of amla is the key to its therapeutic effect. Hence, on the basis of in vitro antioxidative potential, the ethanolic extract of amla (eAE) was selected for in vivo study in NSAID-induced ulcer. Intriguingly, eAE showed biphasic activity in ulcerated mice, with healing effect observed at 60 mg/kg and an adverse effect at 120 mg/kg.The dose-dependent study revealed that switching from anti-oxidant to pro-oxidant shift and immunomodulatory property could be the major cause for its biphasic effect, as evident from the total antioxidant status, thiol concentration, lipid peroxidation, protein carbonyl content followed by mucin content, PGE₂ synthesis and cytokine status. Further, Buthionine sulfoxamine (BSO) pretreatment established the potential impact of antioxidative property in the healing action of eAE. However, eAE efficiently reduced pro-inflammatory cytokine (TNF-α and IL-1β) levels and appreciably upregulate anti-inflammatory cytokine (IL-10) concentration. In conclusion, gastric ulcer healing induced by eAE was driven in a dose-specific manner through the harmonization of the antioxidative property and modulation of anti-inflammatory cytokine level.

Influence of cyclodextrin complexation with NSAIDs on NSAID/cold stress-induced gastric ulceration in rats

The aim of this work was to study the ability of beta-cyclodextrin (beta-CD) or hydroxypropyl beta-cyclodextrin (HP-beta-CD) to ameliorate the induction of gastric ulcers by a nonsteroidal anti-inflammatory drug, indomethacin or piroxicam, in rats exposed to restraint and hypothermic stress at 4 degrees C. Using oral gavage, rats fasted for 72 h were administered the equivalent of a 100 mg/kg dose of the assigned drug, alone or with the designated cyclodextrin (CD). The rats were placed in suitable rodent restrainers and then placed inside a ventilated refrigerator maintained at a temperature of 4 degrees C. Six hours later, each animal was removed, anaesthetized with ether, and the abdomen opened. Each stomach was removed, opened along the greater curvature and gently rinsed with isotonic saline solution. The induced gastric ulcers were examined and assessed with the help of a 10x binocular magnifier. Pronounced and marked gastric ulceration with complete loss of the mucosa, extensive deposition of fibrin and dense neutrophilic infiltrate were observed in rats treated with each of the drugs alone. Treatment with indomethacin or piroxicam alone induced ulcer indices of 26 +/- 2.3 or 14 +/- 1.8, respectively. However, beta-CD and HP-beta-CD each significantly suppressed ulceration due to restraint and cold stress. Rats treated with indomethacin or piroxicam in the presence of either beta-CD or HP-beta-CD exhibited normal tissues. Therefore, beta-CD and HP-beta-CD act as protective agents against gastrointestinal disorders produced by restraint and cold stress, even with the added stress from administration of either indomethacin or piroxicam.

Pro-ulcer effects of resveratrol in mice with indomethacin-induced gastric ulcers are reversed by L-arginine

BACKGROUND AND PURPOSE

Although resveratrol is currently being evaluated in pre-clinical studies as a potential cancer chemopreventive agent and cardiovascular stress-releasing compound, treatment with resveratrol severely delays healing of pre-existing gastric ulcers. Resveratrol treatment can also induce endothelial NOS (eNOS) expression. Here, we have attempted to modulate NO production via eNOS in order to alleviate the pro-ulcer effects of resveratrol.

EXPERIMENTAL APPROACH

Gastric ulcers were induced in mice with a single dose of indomethacin. The effects of pretreatment with l-arginine on the pro-ulcer effects of resveratrol in these mice were then assessed. We measured ulcer damage scores (DS), myeloperoxidase (MPO) activity, generation of prostaglandin E(2) (PGE(2)) and NO, along with a gene expression study.

KEY RESULTS

Resveratrol significantly aggravated damage from indomethacin-induced gastric ulcers, and delayed healing, as shown by increased DS and MPO activity. The mRNA for cyclooxygenase (COX)-1, but not that for COX-2, was inhibited by resveratrol treatment, with reduced synthesis of PGE(2) by gastric tissue. However, resveratrol treatment induced eNOS gene expression and shifted the eNOS/iNOS balance. l-Arginine given before resveratrol in mice with indomethacin-induced ulcers significantly increased tissue NO synthesis and improved ulcer healing.

CONCLUSIONS AND IMPLICATIONS

Exogenous l-arginine increased NO formation via raised levels of eNOS induced by resveratrol and protected against the pro-ulcer effects of resveratrol. Therefore, l-arginine might be useful for alleviation of the pro-ulcer side effects of resveratrol in patients.

Protective and therapeutic effects of resveratrol on acetic acid-induced gastric ulcer

Sprague Dawley rats of both sexes were injected with either saline or RVT (10 mg/kg) either before or after acetic acid ulcer induction and decapitated 3, 5 or 10 days after ulcer. In the saline-treated ulcer groups, macroscopically evident ulcers were observed, while RVT-pretreated or RVT-treated groups had lower macroscopic ulcer scores. Likewise, the microscopic damage scores were lower for the RVT-administered groups. Gastric myeloperoxidase activity, malondialdehyde, collagen and tumour necrosis factor-alpha levels, as well as luminol- and lucigenin-enhanced chemiluminescence levels that were elevated in the saline-administered ulcer groups, were depressed with both RVT-pretreatment and RVT-treatment. Moreover, depleted glutathione levels in the ulcer groups were increased back to control levels by both pre- and post-treatments of RVT. Results demonstrate that resveratrol has both protective and therapeutic effects on oxidative gastric damage by suppressing pro-inflammatory cascades, including the activation of pro-inflammatory cytokines, accumulation of neutrophils and release of oxygen-derived free radicals.

Regulation of arginase/nitric oxide synthesis axis via cytokine balance contributes to the healing action of malabaricone B against indomethacin-induced gastric ulceration in mice

The role of the arginine-metabolism in the healing action of the Myristica malabarica phenol malabaricone B (mal B) and omeprazole against indomethacin-induced stomach ulceration in mouse was investigated. Indomethacin (18 mg kg- 1) was found to induce maximum stomach ulceration in Swiss albino mice on the 3rd day of its administration, which was associated with reduced arginase activity (30.8%, P < 0.01), eNOS expression, along with increased iNOS expression, total NOS activity (5.55 folds, P < 0.001), NO generation (2.19 folds, P < 0.001), and ratio of pro-/anti-inflammatory cytokines. Besides providing comparable healing as omeprazole (3 mg kg- 1 x 3 days), mal B (10 mg kg- 1 x 3 days, p. o.) shifted the iNOS/NO axis to the arginase/polyamine axis as revealed from the increased arginase activity (51.6%, P < 0.001), eNOS expression, and reduced iNOS expression, total NOS activity (approximately 75%, P < 0.001), and NO level (50.6%, P < 0.01). These could be attributed to a favourable anti/pro inflammatory cytokines ratio, generated by mal B. The healing by omeprazole was however, not significantly associated with those parameters.

Protective effects of DIDS against ethanol-induced gastric mucosal injury in rats

The compound 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) is an efficient anion exchanger inhibitor that can block the activities of anion exchanger 2 (AE2), which plays an indispensable role in gastric acid secretion. DIDS also has potent anti-oxidative and antiapoptosis activities. This study aimed to investigate the effect of DIDS on ethanol-induced mucosal damage in rats and to evaluate the underlying mechanisms that mediate the action of the compound. The rats received 1 ml of absolute ethanol or saline orally. DIDS [50 mg/kg intravenous (i.v.)] was given 5 min before ethanol administration. Gastric lesions were evaluated macroscopically, microscopically, and electron microscopically at 60 min after ethanol challenge. Gastric myeloperoxidase (MPO) activity, malonyldialdehyde (MDA) level, prostaglandin E2 (PGE2) synthesis, and cyclooxygenase-2 (COX-2) expression were assessed. For the evaluation of the effect of DIDS on gastric acid secretion, histamine-stimulatory gastric acid secretion was examined with or without pretreatment of DIDS (50 mg/kg; i.v.). Ethanol-induced gastric lesions were characterized by increasing gastric MDA level, MPO activity, and COX-2 expression, and decreasing PGE2 synthesis. It was found that DIDS significantly reduced the extent of gastric mucosal damage and reversed tissue MDA level and MPO activity. DIDS further enhanced the expression of COX-2 and reversed the decrease of PGE2. Our results suggested that DIDS is beneficial in rat model of gastric injury through mechanisms that involve inhibiting inflammatory cell infiltration and lipid peroxidation and up-regulating the COX-2/PGE2 pathway.

A randomized, placebo-controlled study of the effects of naproxen, aspirin, celecoxib or clopidogrel on gastroduodenal mucosal healing

BACKGROUND

Many individuals with gastroduodenal ulcers require on-going, non-steroidal anti-inflammatory drug (NSAID) or anti-platelet therapy.

AIMS

To evaluate the effects of these agents on gastroduodenal mucosal healing.

METHODS

Helicobacter pylori-negative volunteers were randomized to receive naproxen, celecoxib, aspirin, clopidogrel or placebo. Antral and duodenal lesions were created endoscopically with a biopsy forceps. After 7 days of medication dosing, each lesion was scored [from 0 (low) to 8 (high)] using a validated methodology. The primary endpoint was the mean injury score. The secondary endpoint was the percentage of subjects with > or = 1 unhealed lesion.

RESULTS

In all, 108 subjects completed the study. Naproxen impaired antral lesion healing more than placebo, clopidogrel, aspirin or celecoxib (mean injury score of 4.3 vs. 3.0, 2.7, 3.2, and 3.2, respectively, P < 0.05). Naproxen impaired duodenal lesion healing more than placebo, clopidogrel or aspirin (mean injury score of 4.0 vs. 2.4, 2.6, and 2.2, respectively, P < 0.05). More subjects taking naproxen than placebo or clopidogrel had > or =1 unhealed antral lesions (72.2% vs. 36.0% and 32.0%, respectively, P < 0.05) and unhealed duodenal lesions (61.1% vs. 16.0% and 28.0%, respectively, P < 0.05).

CONCLUSIONS

Naproxen may impair gastroduodenal healing more than aspirin or celecoxib in H. pylori negative subjects. Clopidogrel did not impair mucosal healing.

Biphasic activity of resveratrol on indomethacin-induced gastric ulcers

Resveratrol showed biphasic activity in indomethacin-induced gastric ulcerated mice. A protective effect at a lower dose (2 mg kg(-1)) and a contraindicative effect at a higher dose of Resveratrol (10 mg kg(-1)) were observed. This phenomenon was possibly controlled by a COX-1 and eNOS balance, which ultimately maintained angiogenesis in Resveratrol-treated pre-ulcerated mice. The lower dose of Resveratrol (2 mg kg(-1)) augmented eNOS expression without altering COX-1 expression, but, at a higher dose (10 mg kg(-1)), Resveratrol predominantly suppressed COX-1 expression, which significantly reduced both PGE2 synthesis and angiogenesis. Thus it ultimately resulted in delay healing of indomethacin-induced gastric ulcers. Hence, it could be concluded that COX-1 and eNOS acted as key regulatory factors switching the biphasic effects of Resveratrol in indomethacin-induced ulcerated mice.