Prophylactic Effect of Irsogladine Maleate Against Indomethacin-Induced Small Intestinal Lesions in Rats

The effect of irsogladine maleate, a widely used antiulcer drug in Japan, on indomethacin-induced small intestinal lesions was examined in rats. Animals without fasting were given indomethacin (10 mg/kg, s.c.) and sacrificed 24 h later. Irsogladine (1-10 mg/kg) or 16,16-dimethyl prostaglandin E(2) (dmPGE(2) 0.03 mg/kg) was given p.o. twice, 0.5 before and 6 h after indomethacin, while ampicillin (800 mg/kg) was given twice, 18 and 0.5 h before. Indomethacin caused severe lesions in the small intestine, mainly the jejunum and ileum, accompanied by intestinal hypermotility, the up-regulation of inducible nitric oxide synthase (iNOS) expression, and an increase of myeloperoxidase (MPO) activity as well as enterobacterial invasion in the mucosa. These events were all prevented by both dmPGE(2) and ampicillin, except the intestinal hypermotility which was only prevented by dmPGE(2). Likewise, irsogladine also significantly and dose-dependently prevented these lesions at >1 mg/kg. This agent alone increased mucus secretion and significantly suppressed the decreased mucus response to indomethacin, resulting in a suppression of the bacterial invasion as well as the increase in MPO activity and iNOS expression. The protective effect of irsogladine was mimicked by isobutylmethylxanthine, a nonselective inhibitor of phosphodiesterase (PDE), as well as rolipram, a selective PDE4 inhibitor. These results suggest that irsogladine protects the small intestine against indomethacin-induced lesions, and this effect may be associated with the increased mucus secretion, probably due to the inhibitory actions of PDE, resulting in suppression of enterobacterial invasion and iNOS expression.     

Functional mechanism underlying cyclooxygenase-2 expression in rat small intestine following administration of indomethacin: relation to intestinal hypermotility

BACKGROUND AND AIM: We recently reported that cyclooxygenase (COX)-2 is upregulated in the rat small intestine after administration of indomethacin, and this may be the key to non-steroidal anti-inflammatory drug (NSAID)-induced intestinal damage. The present study investigated the mechanism for COX-2 expression induced in the rat small intestine by indomethacin, in relation with ulcerogenic processes. METHODS: Animals were given indomethacin or SC-560 p.o., and the intestinal mucosa was examined 24 h later. RESULTS: Indomethacin caused hemorrhagic lesions in the small intestine, accompanied with an increase in intestinal motility, bacterial invasion and inducible nitric oxide synthase (iNOS) activity, as well as the expression of COX-2 mRNA in the mucosa. Although SC-560 did not cause any damage, this agent caused intestinal hypermotility, the bacterial invasion and the upregulation of COX-2 expression. The mucosal PGE2 content was decreased by SC-560 at 3 h but recovered 12 h later, and this recovery of PGE2 was attenuated by both atropine and ampicillin, in addition to rofecoxib. The intestinal hypermotility response to indomethacin was prevented by both 16,16-dimethyl PGE2 and atropine, but not ampicillin. Yet all these agents inhibited not only the bacterial invasion but also the expression of COX-2 and iNOS activity in the intestinal mucosa following indomethacin treatment, resulting in the prevention of intestinal lesions. CONCLUSION: These results suggest that COX-2 expression in the intestinal mucosa following the administration of indomethacin is associated with intestinal hypermotility and bacterial invasion. The intestinal hypermotility caused by COX-1 inhibition may be a key to COX-2 expression after administration of NSAIDs and their intestinal ulcerogenic properties.     

Functional mechanism underlying cyclooxygenase-2 expression in rat small intestine following administration of indomethacin: Relation to intestinal hypermotility

Background and Aim:  We recently reported that cyclooxygenase (COX)-2 is upregulated in the rat small intestine after administration of indomethacin, and this may be the key to non-steroidal anti-inflammatory drug (NSAID)-induced intestinal damage. The present study investigated the mechanism for COX-2 expression induced in the rat small intestine by indomethacin, in relation with ulcerogenic processes.
Methods:  Animals were given indomethacin or SC-560 p.o., and the intestinal mucosa was examined 24 h later.
Results:  Indomethacin caused hemorrhagic lesions in the small intestine, accompanied with an increase in intestinal motility, bacterial invasion and inducible nitric oxide synthase (iNOS) activity, as well as the expression of COX-2 mRNA in the mucosa. Although SC-560 did not cause any damage, this agent caused intestinal hypermotility, the bacterial invasion and the upregulation of COX-2 expression. The mucosal PGE₂ content was decreased by SC-560 at 3 h but recovered 12 h later, and this recovery of PGE₂ was attenuated by both atropine and ampicillin, in addition to rofecoxib. The intestinal hypermotility response to indomethacin was prevented by both 16,16-dimethyl PGE₂ and atropine, but not ampicillin. Yet all these agents inhibited not only the bacterial invasion but also the expression of COX-2 and iNOS activity in the intestinal mucosa following indomethacin treatment, resulting in the prevention of intestinal lesions.
Conclusion:  These results suggest that COX-2 expression in the intestinal mucosa following the administration of indomethacin is associated with intestinal hypermotility and bacterial invasion. The intestinal hypermotility caused by COX-1 inhibition may be a key to COX-2 expression after administration of NSAIDs and their intestinal ulcerogenic properties.     

Factors Involved in Upregulation of Inducible Nitric Oxide Synthase in Rat Small Intestine Following Administration of Nonsteroidal Anti-inflammatory Drugs

We investigated the functional mechanisms underlying the expression of inducible nitric oxide (NO) synthase (iNOS) in the rat small intestine following the administration of nonsteroidal anti-inflammatory drugs (NSAIDs) and found a correlation with the intestinal ulcerogenic properties of NSAIDs. Conventional NSAIDs (indomethacin, dicrofenac, naproxen, and flurbiprophen), a selective cyclooxygenase (COX)-1 inhibitor (SC-560) and a selective COX-2 inhibitor (rofecoxib) were administered p.o., and the intestinal mucosa was examined 24 hours later. Indomethacin decreased prostaglandin E₂ (PGE₂) production in the intestinal mucosa and caused intestinal hypermotility and bacterial invasion as well as the upregulation of iNOS expression and NO production, resulting in hemorrhagic lesions. Other NSAIDs similarly inhibited PGE₂ production and caused hemorrhagic lesions with intestinal hypermotility as well as iNOS expression. Hypermotility in response to indomethacin was prevented by both PGE₂ and atropine but not ampicillin, yet all these agents inhibited not only bacterial invasion but also expression of iNOS as well, resulting in prevention of intestinal lesions. SC-560, but not rofecoxib, caused a decrease in PGE₂ production, intestinal hypermotility, bacterial invasion, and iNOS expression, yet this agent neither increased iNOS activity nor provoked intestinal damage because of the recovery of PGE₂ production owing to COX-2 expression. Food deprivation totally attenuated both iNOS expression and lesion formation in response to indomethacin. In conclusion, the expression of iNOS in the small intestine following administration of NSAIDs results from COX-1 inhibition and is functionally associated with intestinal hypermotility and bacterial invasion. This process plays a major pathogenic role in the intestinal ulcerogenic response to NSAIDs.     

Protective effect of lafutidine against indomethacin-induced intestinal ulceration in rats: relation to capsaicin-sensitive sensory neurons

BACKGROUND/AIM: We examined the prophylactic effect of lafutidine, a novel histamine H(2)-receptor antagonist [(+/-)-2-(furfurylsulfinyl)-N-[4-[4-(piperidinomethyl)-2-pyr idyl]oxy- (Z)-2 butenyl]acetamide], on indomethacin-induced small intestinal ulcers in rats and investigated the relation of this action to capsaicin-sensitive sensory neurons. METHODS AND RESULTS: Subcutaneously administered indomethacin (10 mg/kg) provoked ulceration in the small intestine, mainly the jejunum and ileum, accompanied by increases in myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities as well as the enterobacterial numbers invading the mucosa. Intestinal ulcerogenic response to indomethacin was prevented by 16,16-dimethyl prostaglandin E(2) (10 microg/kg, p.o.) and capsaicin (10 mg/kg, p.o. ) as well as ampicillin (800 mg/kg, p.o.), but not omeprazole (100 mg/kg, p.o.). Likewise, lafutidine (1-10 mg/kg, p.o.), but not cimetidine (100 mg/kg, p.o.), reduced the occurrence of intestinal ulcers in response to indomethacin in a dose-dependent manner, and a significant effect was observed at 3 mg/kg or greater. The protective action of lafutidine as well as capsaicin was almost totally abolished by chemical ablation of capsaicin-sensitive sensory neurons. Both lafutidine and capsaicin significantly suppressed the increases in MPO and iNOS activities as well as enterobacterial numbers in the mucosa. These agents also significantly enhanced mucus secretion in the small intestine. CONCLUSION: These results suggest that lafutidine protects the small intestine against ulceration via stimulation of capsaicin-sensitive sensory neurons. This action may be attributable to inhibition of enterobacterial invasion in the intestinal mucosa, probably by increasing the mucus secretion.     

Protective effect of rebamipide on indomethacin-induced intestinal damage in rats

BACKGROUND AND AIM: We evaluated the effect of rebamipide (2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl] propionic acid), a novel anti-ulcer drug, on indomethacin-induced small intestinal lesions in rats. METHODS: The animals were administered indomethacin (10 mg/kg, s.c.), and they were killed 24 h later. Rebamipide (30-300 mg/kg) was administered p.o. twice, 30 min before, and 6 h after indomethacin. RESULTS: Indomethacin caused hemorrhagic lesions in the rat small intestine, accompanied by an increase in enterobacterial translocation, inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) activities, as well as thiobarbituric acid (TBA) reactants, and these changes were significantly prevented by the supplementation with 16,16-dimethyl prostaglandin E2 (dmPGE2; 10 microg/kg, i.v.) or the pretreatment of animals with the antibiotic ampicillin. Treatment of the animals with rebamipide dose-dependently prevented the development of intestinal lesions, and this effect was mimicked by i.v. administration of superoxide dismutase (SOD: 3000 U/kg) + catalase (CAT: 5000 U/kg). The protection by rebamipide was accompanied by a significant suppression of the increase in both MPO and iNOS activities, and a complete inhibition of the increase in TBA reactants, while SOD + CAT significantly inhibited the increase of MPO activity and TBA reactants, but not iNOS activity. The bacterial translocation following indomethacin was also significantly decreased by either rebamipide or SOD + CAT. CONCLUSION: These results confirmed the importance of enterobacteria and iNOS/NO in the pathogenesis of indomethacin-induced small intestinal lesions, and suggested that rebamipide prevents the development of these lesions, probably by its radical scavenging action.     

Sildenafil, an Inhibitor of Phosphodiesterase Subtype 5, Prevents Indomethacin-Induced Small-Intestinal Ulceration in Rats via a NO/cGMP-Dependent Mechanism

We examined the effect of sildenafil, an inhibitor of phosphodiesterase subtype 5, that catalyzes hydrolysis of 3′,5′-cyclic guanosine monophosphate (cGMP), on indomethacin-induced small-intestinal ulceration in rats and investigated the mechanism of this action, especially in relation to endogenous nitric oxide (NO). Animals without fasting were given indomethacin (10 mg/kg) s.c. and then killed 24 h later. Indomethacin produced hemorrhagic lesions in the small intestine, accompanied by a promotion of enterobacterial invasion and the expression of inducible NO synthase (iNOS) as well as myeloperoxidase (MPO) activity in the mucosa. Sildenafil (3–20 mg/kg), given p.o. 30 min before indomethacin, dose-dependently reduced the severity of these lesions, with concomitant suppression of the increase in MPO activity, iNOS expression and bacterial invasion. These effects were attenuated by the prior administration of the nonselective NOS inhibitor, N ^G-nitro-l-arginine methyl ester, in an l-arginine-reversible manner. Indomethacin also decreased the secretion of mucus and fluid (enteropooling) and enhanced intestinal motility, but these responses were all prevented by the prior administration of sildenafil. Likewise, pretreatment of the animals with NOR-3, a NO donor, also reversed the functional changes caused by indomethacin, followed by suppression of bacterial invasion and iNOS expression, and prevented the development of intestinal lesions. These results suggest that sildenafil prevents indomethacin-induced small-intestinal ulceration in rats, via a NO/cGMP-dependent mechanism, and this effect is functionally associated with an increase in the secretion of mucus/fluid and a decrease of hypermotility, resulting in the suppression of bacterial invasion and iNOS expression following indomethacin treatment.     

Bilateral adrenalectomy worsens gastric mucosal lesions induced by indomethacin in the rat. Role of enhanced gastric motility

The mechanism by which bilateral adrenalectomy worsens indomethacin-induced gastric lesions was investigated in rats. In sham-operated rats subcutaneously administered indomethacin produced gastric lesions at doses of 10 mg/kg body wt or greater, in association with lowering of blood glucose levels. In a parallel study, indomethacin induced gastric hypermotility at the same dose levels but had no effect on acid output or mucosal blood flow even at 25 mg/kg body wt. Adrenalectomy (2 wk) itself significantly reduced the blood glucose levels (approximately 50%) and markedly potentiated the ulcerogenic and motility responses caused by indomethacin; the ED50 values dropped to approximately 10 times lower than those in sham-operated rats. Both acid output and mucosal blood flow were significantly reduced by adrenalectomy, but these values were increased after indomethacin treatment (3 mg/kg body wt). The ulcerogenic and motility responses caused by indomethacin were significantly reduced by acute infusion of glucose (25% wt/wt, 1.2 ml/h) intravenously in both sham-operated and adrenalectomized rats, and by subcutaneous administration of hydrocortisone acetate (10 mg/kg body wt for 2 wk) in the latter group. When the motility and the ulcer score were determined in the same animals, a highly significant relationship was found between these two factors in both sham-operated and adrenalectomized rats. These results suggest that (a) the increased gastric motility may be a key element in the pathogenesis of indomethacin-induced lesions and in the mechanism for aggravation of the lesions and in the mechanism for aggravation of the lesions by adrenalectomy, and (b) abrasion of adrenal glands by inducing hypoglycemia may sensitize the system to indomethacin and increase gastric motility.     

Prevention by parenteral aspirin of indomethacin-induced gastric lesions in rats: mediation by salicylic acid

Nonsteroidal antiinflammatory drugs (NSAIDs) produce gastric damage in experimental animals, irrespective of the route of administration. However, aspirin (ASA) causes damage only when it is given orally. In the present study, we examined the gastric ulcerogenic effect of subcutaneously administered ASA in rats, in comparison with various NSAIDs, and investigated the reason why ASA does not cause damage in the stomach, in relation to its metabolite salicylic acid (SA). Since the antiinflammatory action of SA is known to be mediated, partly, by endogenous adenosine (AD), we also examined the possible involvement of AD in the protective action of SA. Various NSAIDs (indomethacin, flurbiprofen, naproxen, diclrofenac, ASA, SA) were administered subcutaneously, and the gastric mucosa was examined macroscopically 4 hr later. All NSAIDs tested, except ASA and SA, caused hemorrhagic lesions in the stomach, with a marked gastric hypermotility and a decrease of mucosal PGE₂ contents. These ulcerogenic and motility responses caused by NSAIDs were blocked by pretreatment with atropine or PGE₂. ASA, although inhibiting PGE₂ generation, caused neither hypermotility nor damage in the stomach. On the other hand, SA alone inhibited basal gastric motility without any effect on mucosal PGE₂ contents, and this agent, when given together with indomethacin, prevented gastric hypermotility and lesion formation in response to indomethacin, without affecting the reduced PGE₂ contents. Likewise, ASA inhibited these responses to indomethacin, yet the effects appeared later than those of SA. Following administration of ASA, the blood SA levels reached a peak within 30 min and remained elevated for 4 hr. In addition, the protective effect of SA was not significantly influenced by either the AD deaminase or the AD-receptor antagonists. These results suggest that the failure of parenteral ASA to induce gastric damage may be explained by a protective action of SA metabolized from ASA. SA has a cytoprotective action against NSAID-induced gastric lesions, and this action is not mediated by endogenous AD but may be functionally associated with inhibition of the gastric motility response.     

16,16-Dimethyl Prostaglandin E2 Inhibits Indomethacin-Induced Small Intestinal Lesions Through EP3 and EP4 Receptors

We evaluated the effect of various PGE analogs specific to EP receptor subtypes on indomethacin-induced small intestinal lesions in rats and investigated the relationship of EP receptor subtype with the PGE action using EP receptor knockout mice. Animals were administered indomethacin subcutaneously, and they were killed 24 hr later. 16,16-dimethyl prostaglandin E₂ (dmPGE₂) or various EP agonists were administered intravenously 10 min before indomethacin. Indomethacin caused hemorrhagic lesions in the rat small intestine, accompanied with an increase in intestinal motility and the number of enteric bacteria as well as iNOS and MPO activities. Prior administration of dmPGE₂ dose-dependently prevented intestinal lesions, together with inhibition of those functional changes. These effects of dmPGE₂ were mimicked by prostanoids (ONO-NT-012 and ONO-AE1-329), only specific to EP3 or EP4 receptors, although the intestinal motility was inhibited only by ONO-AE1-329. Intestinal mucus secretion and fluid accumulation were decreased by indomethacin but enhanced by dmPGE₂, ONO-NT-012, and ONO-AE1-329 at the doses that prevented intestinal lesions. Indomethacin also caused intestinal lesions in both wild-type and knockout mice lacking EP1 or EP3 receptors, yet the protective action of dmPGE₂ was observed in wild-type and EP1 receptor knockout mice but not the mice lacking EP3 receptors. These results suggest that the intestinal cytoprotective action of PGE₂ against indomethacin is mediated by EP3/EP4 receptors and that this effect is functionally associated with an increase of mucus secretion and enteropooling as well as inhibition of intestinal hypermotility, the former two processes mediated by both EP3 and EP4 receptors, and the latter by EP4 receptors.     

Possible mechanisms involved in gastric hypermotility caused by indomethacin in the rat

Pathogenesis of indomethacin-induced gastric lesions was investigated in the rat by measuring lesions, gastric motility, and terminal blood glucose levels and correlating them with each other. Subcutaneously administered indomethacin (3-25 mg/kg) dose-dependently produced lesions in the stomach with concomitant gastric hypermotility and reduction of blood glucose levels. When the lesion score and the motility were plotted against terminal glucose levels, a highly significant relationship was found among these three factors (P less than 0.01). Gastric lesions and hypermotility induced by indomethacin (25 mg/kg) were suppressed significantly by 16,16-dmPGE2 (10 micrograms/kg) with no effect on the glucose levels, while intravenous infusion of glucose (25% w/w, 1.4 ml/hr) prevented these responses and restored the reduced glucose levels above the basal values. In addition, both 16,16-dmPGE2 and glucose infusion afforded a significant protection against gastric lesions induced by indomethacin even in the acid-perfused stomach (150 mM HCl). These results confirmed gastric hypermotility as a key element in the pathogenesis of indomethacin-induced lesions and further suggested that indomethacin may sensitive gastric contractility through glycoprivic receptors by inducing hypoglycemia and PG deficiency.     

Influences of urethane anesthesia on indomethacin-induced gastric mucosal lesions in rats

Effects of urethane on gastric motility and mucosal ulcerogenic responses induced by indomethacin were investigated in the rat in relation to blood glucose levels (BGL) and compared with those of pentobarbital Na. Urethane (1.25 g/kg) given intraperitoneally, caused a progressive and significant rise in BGL, while pentobarbital (30 mg/kg) given intraperitoneally did not affect BGL. Subcutaneous administration of indomethacin (25 mg/kg) caused high-amplitude gastric contractions and induced hemorrhagic lesions in the stomachs of conscious rats. These lesions were significantly inhibited by urethane but not pentobarbital. Administration of urethane abolished basal gastric motility and almost completely suppressed the motility responses induced by indomethacin, while pentobarbital did not have much effect on gastric motility under basal and indomethacin-stimulated conditions. Acid secretion was significantly decreased by urethane and increased by pentobarbital. Pretreatment of the animals with yohimbine (5 mg/kg, subcutaneously) but not prazosin (0.5 mg/kg) inhibited the elevation in BGL seen after administration of urethane and allowed resumption both gastric motility and ulcerogenic responses induced by indomethacin, with less change in acid secretion. These results suggest that intraperitoneal administration of urethane prevented indomethacin-induced gastric lesions, probably by inhibiting the enhanced gastric motility response, and this effect may relate to its hyperglycemic action mediated by ₂-adrenoceptors. These findings also provide further evidence to support the importance of gastric motility in the pathogenesis of these lesions.     

Soluble Dietary Fiber Protects Against Nonsteroidal Anti-inflammatory Drug-Induced Damage to the Small Intestine in Cats

Purpose  

Nonsteroidal anti-inflammatory drugs (NSAIDs) often cause ulcers in the small intestine in humans, but there are few effective agents for treatment of small intestinal ulcers. We found that soluble dietary fibers (SDFs), such as pectin, could prevent the formation of small intestinal lesions induced by indomethacin (IND) in cats. To elucidate the mechanism of protection by SDFs, we examined the viscosities of SDFs and the effects of pectin on gastrointestinal absorption of IND and intestinal hypermotility induced by IND.     

Sodium alginate ameliorates indomethacin-induced gastrointestinal mucosal injury via inhibiting translocation in rats

AIM:To investigate the effects of sodium alginate(ALNa)on indomethacin-induced small intestinal lesions in rats.METHODS:Gastric injury was assessed by measuring ulcerated legions 4 h after indomethacin(25 mg/kg)administration.Small intestinal injury was assessed by measuring ulcerated legions 24 h after indomethacin(10mg/kg)administration.AL-Na and rebamipide were orally administered.Myeloperoxidase activity in the stomach and intestine were measured.Microvascular permeability,superoxide dismutase content,glutathione peroxidase activity,catalase activity,red blood cell count,white blood cell count,mucin content and enterobacterial count in the small intestine were measured.RESULTS:AL-Na significantly reduced indomethacininduced ulcer size and myeloperoxidase activity in the stomach and small intestine.AL-Na prevented increases in microvascular permeability,superoxide dismutase content,glutathione peroxidase activity and catalase activity in small intestinal injury induced by indomethacin.AL-Na also prevented decreases in red blood cells and white blood cells in small intestinal injury induced by indomethacin.Moreover,AL-Na suppressed mucin depletion by indomethacin and inhibited infiltration of enterobacteria into the small intestine.CONCLUSION:These results indicate that AL-Na ameliorates non-steroidal anti-inflammatory drug-induced small intestinal enteritis via bacterial translocation.     

Pathogenesis of NSAID-induced gastric damage: importance of cyclooxygenase inhibition and gastric hypermotility

This article reviews the pathogenic mechanism of non-steroidal anti-inflammatory drug (NSAID)-induced gastric damage, focusing on the relation between cyclooxygenase (COX) inhibition and various functional events. NSAIDs, such as indomethacin, at a dose that inhibits prostaglandin (PG) production, enhance gastric motility, resulting in an increase in mucosal permeability, neutrophil infiltration and oxyradical production, and eventually producing gastric lesions. These lesions are prevented by pretreatment with PGE₂ and antisecretory drugs, and also via an atropine-sensitive mechanism, not related to antisecretory action. Although neither rofecoxib (a selective COX-2 inhibitor) nor SC-560 (a selective COX-1 inhibitor) alone damages the stomach, the combined administration of these drugs provokes gastric lesions. SC-560, but not rofecoxib, decreases prostaglandin E₂ (PGE₂) production and causes gastric hypermotility and an increase in mucosal permeability. COX-2 mRNA is expressed in the stomach after administration of indomethacin and SC-560 but not rofecoxib. The up-regulation of indomethacin-induced COX-2 expression is prevented by atropine at a dose that inhibits gastric hypermotility. In addition, selective COX-2 inhibitors have deleterious influences on the stomach when COX-2 is overexpressed under various conditions, including adrenalectomy, arthritis, and Helicobacter pylori-infection. In summary, gastric hypermotility plays a primary role in the pathogenesis of NSAID-induced gastric damage, and the response, causally related with PG deficiency due to COX-1 inhibition, occurs prior to other pathogenic events such as increased mucosal permeability; and the ulcerogenic properties of NSAIDs require the inhibition of both COX-1 and COX-2, the inhibition of COX-1 upregulates COX-2 expression in association with gastric hypermotility, and PGs produced by COX-2 counteract the deleterious effect of COX-1 inhibition.     

Reduced small-intestinal injury induced by indomethacin in interleukin-17A-deficient mice

Background and Aims: The pathogenesis of enteropathy induced by non‐steroidal anti‐inflammatory drugs (NSAIDs) is still unclear, and there are no established treatments. Interleukin‐17A (IL‐17A) is a pro‐inflammatory cytokine that has been associated with the development of chronic inflammatory diseases, including autoimmune diseases. To define the role of IL‐17A in small intestinal injury and inflammation, we studied the effects of indomethacin administration in mice with targeted deletions of the IL‐17A gene. Methods: Male C57BL/6 (wild‐type) and homozygous IL‐17A^‐/‐ C57BL/6 mice were subjected to this study. Indomethacin (10 mg/kg) was subcutaneously administered to induce small‐intestinal damage. Indomethacin‐induced lesions in the small intestine were evaluated by measuring the injured area and by histopathology. Also assessed were myeloperoxidase (MPO) activity, as an index of neutrophil accumulation, and intestinal mRNA expression for inflammatory cytokines. Results: The area of macroscopic ulcerative lesions, the MPO activity and the mRNA expression of inflammatory‐associated chemokines, such as keratinocyte chemoattractant (KC), monocyte chemotactic protein‐1 (MCP‐1), and granulocyte‐colony stimulating factor (G‐CSF), were significantly increased in indomethacin‐treated groups compared with the sham groups. The development of intestinal lesions by indomethacin was inhibited in IL‐17A^‐/‐ mice compared with wild‐type mice, together with significant suppression of the increased levels of MPO activities and KC, MCP‐1, and G‐CSF levels. Conclusion: These findings demonstrate that IL‐17A contributes to the development of indomethacin‐induced small intestinal injury through upregulation of G‐CSF, KC, and MCP‐1. IL‐17A might be a promising new therapeutic target to treat NSAID‐induced enteritis.     

Interaction Between NSAIDs and Steroid in Rat Stomach

The relative risk of development of peptic ulcer with the use of nonsteroidal antiinflammatory drugs (NSAIDs) has been reported to increase when these drugs are administered in combination with steroids. We investigated the ulcerogenic potential of a combination of NSAIDs and steroids in rats and the underlying pathogenic mechanisms. Indomethacin alone produced gastric lesions, and the severity of the lesions markedly increased with concomitant administration of prednisolone. However, nimesulide, even in excessive doses, did not produce any gastric lesions, regardless of concomitant administration with prednisolone. Furthermore, we showed that the ulcerogenic potential of indomethacin administered in combination with prednisolone may be related to the induction of physiological changes, such as endogenous prostaglandin deficiency, an increase in neutrophil activation, and gastric hypermotility, by indomethacin and alteration of normal epithelial renewal by the steroid. These results suggest that the ulcerogenic potential of preferential a COX-1 inhibitor increases following concomitant administration with a steroid, whereas, nimesulide, a preferential COX-2 inhibitor, is nonulcerogenic, even when administered concomitantly with a steroid, and is therefore a clinically useful antiinflammatory agent.     

Oxygen free radicals and lipid peroxidation in the pathogenesis of gastric mucosal lesions induced by indomethacin in rats. Relation to gastric hypermotility.

The relationship of gastric hypermotility to mucosal hemodynamics, lipid peroxidation and vascular permeability changes was investigated in the pathogenesis of indomethacin-induced gastric lesions in rats. Subcutaneous administration of indomethacin (25 mg/kg) produced an increase in both the amplitude and frequency of stomach contraction from 30 min after treatment, resulting in hemorrhagic damage 2 h later. Gastric mucosal blood flow measured by a Laser flowmetry showed oscillatory fluctuations under hypercontractile states: a decrease during contraction followed by an increase during relaxation. Mucosal lipid peroxidation and vascular permeability were significantly increased with time after indomethacin treatment, and these changes preceded the appearance of hemorrhagic damage. All these events were prevented when gastric hypermotility was inhibited by atropine or 16,16-dimethyl prostaglandin E2. Pretreatment of the animals with allopurinol and hydroxyurea or continuous infusion of superoxide dismutase and dimethyl sulfoxide during a test period also attenuated these functional changes and mucosal lesions induced by indomethacin, without affecting the motility response. We conclude that oxygen free radicals may play a role in the development of mucosal lesions associated with gastric hypermotility in indomethacin-treated rats.     

非甾体抗炎药对小肠黏膜的损伤作用

研究显示非甾体抗炎药（NSAIDs）不仅可引起胃十二指肠黏膜损伤，还可引起小肠黏膜损伤。目的：探讨NSAIDs引起小肠黏膜损伤的发病机制及其病理生理变化。方法：50只大鼠随机分为空白对照组和四组模型组，以不同NSAID灌胃14d。另20只大鼠先分别行胆管结扎和假手术。再予吲哚美辛灌胃。观察各组大鼠一般情况和小肠黏膜大体、组织病理学改变，测定小肠组织髓过氧化物酶（MPO）、丙二醛（MDA）、超氧化物歧化酶（SOD）、一氧化氮（NO）含量。结果：四种NSAID均能造成大鼠小肠黏膜损伤，吲哚美辛、布洛芬和塞来昔布组累计损伤深度和面积显著高于空白对照组（P〈0．05），其中以吲哚美辛组损伤最重，阿司匹林组则与空白对照组无明显差异。各模型组小肠组织MPO含量均显著高于空白对照组，SOD活性则显著低于空白对照组（P〈0．05），MDA和NO含量均呈上升趋势，但分别仅吲哚美辛组和布洛芬组与空白对照组相比有显著差异（P〈0．05）。假手术组小肠黏膜损伤显著重于空白对照组（P〈0．05），胆管结扎组与空白对照组相比无明显差异。结论：NSAIDs可通过炎症反应、氧自由基损伤、NO过度产生以及药物的肝肠循环损害小肠上皮屏障，破坏小肠结构的完整性。     

Indomethacin-induced small intestinal injury is ameliorated by cilostazol, a specific PDE-3 inhibitor

Abstract Background. Neutrophil migration, one of the major factors predisposing to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced intestinal lesions, consists of several steps, including interaction with P-selectin from platelets. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, suppresses the expression of P-selectin from platelets and reduces interaction between platelets and leukocytes, leading to inflammatory amelioration in several disease models. We tried to clarify the therapeutic effectiveness of cilostazol for NSAID-induced small intestinal lesions. Subjects and methods. 1) Anti-PSGL-1 antibody (2 mg/kg) or cilostazol (100 mg/kg) was administered to mice one hour before Indomethacin (IND, 2.5 mg/kg) administration for 4 days to evaluate small intestinal lesions. 2) IND-induced migratory behaviors of neutrophils and platelets were evaluated in intestinal vessels by an intravital microscopy. Results. i) IND induced small intestinal lesions with an increase in MPO activity. Anti-PSGL-1 antibody and cilostazol ameliorated intestinal lesions along with suppression of MPO activity. ii) Intravital microscopy revealed that administration of IND increased migration of platelet-bearing neutrophils. Cilostazol treatment ameliorated neutrophil migration by blocking interaction between platelets and neutrophils. Conclusion. Our results suggest that enhanced platelets-bearing neutrophil migration is critically involved in the pathogenesis of IND-induced small intestinal lesions and suggest a potential application of cilostazol for prevention of NSAID-induced small intestinal lesions.