Effect of ebrotidine on gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide.

Helicobacter pylori lipopolysaccharide is a primary virulence factor responsible for eliciting acute mucosal inflammatory responses associated with H. pylori infection. In this study, we applied the animal model of H. pylori lipopolysaccharide-induced acute gastritis to assess the effect of antiulcer agent, ebrotidine, on the gastric mucosal inflammatory responses by analyzing the interplay between the activity of a key apoptotic caspase, caspase-3, epithelial cell apoptosis, and the expression of inducible nitric oxide synthase (NOS-2). METHODS: Rats, pretreated twice daily with ebrotidine at 100 mg/kg, or the vehicle, were subjected to intragastric application of H. pylori lipopolysaccharide at 50 microg/animal, and after 4 additional days on the antiulcer drug or vehicle regimen their mucosal tissue used for histologic assessment, assays of epithelial cells apoptosis, and the measurements of caspase-3 and NOS-2 activities. RESULTS: In the absence of antiulcer agent, H. pylori lipopolysaccharide induced acute reaction characterized by the inflammatory infiltration of the lamina propria, hyperemia, and epithelial hemorrhage. This was accompanied by an 11.2-fold increase in epithelial cell apoptosis, a 6.5-fold induction in mucosal expression of NOS-2, and a 5.4-fold increase in caspase-3 activity. Treatment with H2-receptor antagonist ebrotidine, also known for its gastroprotective effects, produced a 50.9% reduction in the extent of mucosal inflammatory changes elicited by H. pylori lipopolysaccharide and an 82.5% decrease in the epithelial cells apoptosis, while the activity of caspase-3 decreased by 33.7% and that of NOS-2 showed a 72.8% decline. CONCLUSIONS: The findings implicate caspase-3 involvement in gastric mucosal inflammatory responses to H. pylori lipopolysaccharide, and point towards participation of NOS-2 in the amplification of the cell death-signaling cascade. Our study also demonstrate that ebrotidine exerts modulatory effect on the H. pylori-induced mucosal inflammatory responses by interfering with the events propagated by NOS-2 and caspase-3.     

Omeprazole fails to suppress up-regulation of gastric mucosal endothelin-converting enzyme-1 by Helicobacter pylori lipopolysaccharide.

BACKGROUND: Endothelin-1, a key mediator of inflammatory processes, is produced from its biologically inactive precursor, big ET- by the action of endothelin converting enzyme-1(ECE-1). In this study, we applied the animal model of H. pylori lipopolysaccharide-induced gastritis to assess the effect of three different types of antiulcer agents on the gastric mucosal expression of ECE-1 activity. METHODS: Rats, pretreated twice daily for 3 days with proton pump inhibitor, omeprazole at 40 mg/kg, gastroprotective agent, sulglycotide at 200 mg/kg, H2-receptor antagonist, ebrotidine at 100 mg/kg or the vehicle, were subjected to intragastric application of H. pylori lipopolysaccharide at 50 microg/animal, and after 2, and 4 additional days on the drug or vehicle regimen their mucosal tissue used for histologic and biochemical assessment. RESULTS: In the absence of antiulcer agents, H. pylori lipopolysaccharide elicited a pattern of mucosal inflammatory responses resembling that of acute gastritis which reached a maximum by the 4th day and were accompanied by a 4.1-fold increase in the mucosal expression of ECE-1 activity and an 8.8-fold enhancement in TNF-alpha. Treatment with sulglycotide led to a 56.7% reduction in the extent of mucosal inflammatory involvement, the mucosal expression of ECE-1 activity fell by a 40.5% and the level of TNF-alpha declined by a 69%. Ebrotidine produced a 50.9% decrease in the extent of mucosal inflammatory involvement, a 33.6% decrease in the expression of ECE-1 activity and a 64.1% decline in TNF-alpha, whereas omeprazole elicited a 37.6% reduction in the extent of mucosal inflammatory involvement and a 29.5% decrease in TNF-alpha, but had no effect on the lipoploysaccharide-induced increase in the mucosal expression of ECE-1 activity. CONCLUSIONS: The findings implicate up-regulation of ECE-1 in triggering the induction of TNF-alpha and propagation of gastric mucosal inflammatory responses to H. pylori. We also show that omeprazole, in contrast to sulglycotide and ebrotidine, fails to counter the enhancement in the mucosal expression of ECE-1 caused by H. pylori- lipopolysaccharide.     

Up-regulation of endothelin-1 in gastric mucosal inflammatory responses to Helicobacter pylori Lipopolysaccharide: effect of omeprazole and sucralfate.

BACKGROUND: Helicobacter pylori is recognized as a primary etiologic factor in the development of gastric disease and the product of particular significance to the virulent action of the bacterium is its cell wall lipopolysaccharide. We applied the animal model of H. pylori lipopolysaccharide-induced acute gastritis to study the effect of antiulcer agents, omeprazole and sucralfate, on the course of mucosal inflammatory responses by analyzing the interplay between the extent of epithelial cell apoptosis and the mucosal expression of endothelin-1 (ET-1), tumor necrosis factor-alpha (TNF-alpha), and the activity of constitutive (cNOS) and inducible (NOS-2) nitric oxide synthase. METHODS: Rats pretreated twice daily for 3 consecutive days with omeprazole at 40 mg/kg, sucralfate at 100 mg/kg or the vehicle, were subjected to intragastric application of H. pylori lipopolysaccharide at 50 microg/animal, and after 2, 4, and 10 additional days on the antiulcer drug or vehicle regimen their mucosal tissue used for histologic and biochemical assessment. RESULTS: In the absence of antiulcer agents, H. pylori lipopolysaccharide elicited within 2 days a pattern of acute mucosal inflammatory responses accompanied by a massive epithelial cell apoptosis, a 2.9-fold increase in the mucosal expression of ET-1, an 11.7-fold enhancement in TNF-alpha, and a 9.3-fold increase in NOS-2, while cNOS activity showed a 5.5-fold decrease. The extent of mucosal inflammatory involvement reached a maximum by the 4th day and showed a decline by the 10th day. This was reflected in a marked reduction in epithelial cell apoptosis, decrease in the mucosal expression of ET-1, TNF-alpha and NOS-2, and the recovery in cNOS activity. Comparing to the vehicle controls, treatment with proton pump inhibitor, omeprazole, led at the end of a 10 day period to a 48.3% reduction in the extent of mucosal inflammatory involvement elicited by H. pylori lipopolysaccharide, while a 74.2% reduction in the mucosal inflammatory involvement was achieved with gastroprotective agent, sucralfate. Moreover, this advantage of sucralfate over omeprazole in countering the lipopolysaccharide-induced changes was reflected at the end of 10 day treatment period in a 20.4% greater decrease in apoptosis, a 47.5% greater reduction in TNF-alpha and a 50.7% greater reduction in ET-1. However, both agents exerted similar influence on the restoration of gastric mucosal cNOS activity and showed a comparable effect at the end of a 10 day treatment in countering the lipopolysaccharide-induced increase in the expression of NOS-2. CONCLUSIONS: The findings suggest that an increase in the mucosal ET-1 level elicited by H. pylori lipopolysaccharide, combined with a decline in cNOS may be responsible for the induction of TNF-alpha and triggering the inflammatory process. We also show that sucralfate exhibits greater efficacy than omeprazole in suppressing the H. pylori-induced mucosal inflammatory responses. This property of sucralfate may well be due to its ability to suppress the mucosal rise in ET-1.     

Role of interleukin-4 in down-regulation of endothelin-1 during gastric ulcer healing: effect of sucralfate.

BACKGROUND: The course of events associaed with healing gastric mucosal injury involves an orderly interplay between the array of signaling molecules that exert their influence on the processes leading to the restoration of the mucosal integrity. In this study, we investigated the effect of antiulcer agent, sucralfate, on the mucosal apoptotic processes during gastric ulcer healing by analyzing the expression of interleukin-4 (IL:4), endothelin-1 (ET-1), tumor necrosis factor-alpha (TNF-alpha), and the mucosal activity of capase-3, and constitutive (cNOS) and inducible nitric oxide synthase (NOS-2). METHODS: Rats with experimentally induced chronic gastric ulcers were administered twice daily for 14 days either sucralfate at 100 mg/kg or vehicle, and at different stages of treatment their stomachs were used for macroscopic and biochemical assessments. RESULTS: The ulcer onset was characterized by a massive epithelial apoptosis associated with a 33-fold increase in caspase-3 activity, 5.7-fold increase in TNF-alpha, 17.5-fold increase in NOS-2 and a 3.9-fold increase in ET-1, while the mucosal expression of cNOS activity showed a 7.6-fold drop and IL-4 expression fell by 37.2%. The healing was reflected in a rapid recovery in IL-4, and a decrease in apoptosis, caspase-3, TNF-alpha, ET-1 and NOS-2, and a slow recovery in cNOS activity, and the process was accelerated in the sucralfate-treated group. While in the absence of sucralfate the expression of IL-4 returned to that of the normal mucosa by the 7th day of healing and that of ET-1 and TNF-alpha by the 14th day, an accelerated ulcer healing with sucralfate treatment was associated with IL-4 recovery by the 4th day and that of ET-1 and TNF-alpha by the 10th day when the ulcer heated, while recovery in cNOS activity required 14 days. Yet, in both groups of animals the apoptotic DNA fragmentation rate, caspase-3 and the expression of NOS-2 activity remained significantly elevated even after the ulcer healed. CONCLUSIONS: The results suggest that a decrease in the mucosal expression of the regulatory cytokine IL-4 at the ulcer onset may well be a key factor causing dysregulation of ET-1 production, induction of TNF-alpha, and triggering the apoptotic events that affect the efficiency of mucosal repair process. We also show that accelerated ulcer healing by sucralfate may be the result of a rapid mucosal IL-4 generation that leads to the suppression of the mucosal apoptotic events.     

Downregulation of endothelin-1 by interleukin-4 during gastric ulcer healing.

We investigated the course of events associated with gastric ulcer healing by analyzing mucosal expression of interleukin-4 (IL-4), endothelin-1 (ET-1), tumor necrosis factor-alpha (TNF-alpha), and the activity of constitutive (cNOS) and inducible nitric oxide synthase (NOS-2). Ulcer onset was characterized by a massive epithelial apoptosis associated with a 5.7-fold increase in TNF-alpha, a 17.5-fold increase in NOS-2, and a 3.9-fold increase in ET-1, while mucosal expression of cNOS showed a 7.6-fold drop and IL-4 fell by 37.2%. Healing was accompanied by a rapid raise in IL-4; decrease in apoptosis, TNF-alpha, ET-1, and NOS-2; and a slow recovery in cNOS. The expression of IL-4 returned to control levels by the 7th day of healing and that of ET-1 and TNF-alpha by the 14th day, while apoptotic DNA fragmentation and the activity of NOS-2 remained significantly elevated beyond the 14-day period. The results suggest that a decrease in the mucosal level of IL-4 at ulcer onset may well be a key factor causing dysregulation of ET-1 production, induction of TNF-alpha, and triggering the apoptotic events that affect the efficiency of mucosal repair.     

Nonsteroidal anti-inflammatory drugs impair oral mucosal repair by eliciting disturbances in endothelin-converting enzyme-1 and constitutive nitric oxide synthase.

Although the use of nonsteroidal anti-inflammatory drugs (NSAIDs) is known to cause the impairment in mucosal defenses that are well recognized and clinically emphasized with respect to the gastrointestinal tract, less apparent is the extent of their interference with the repair of soft oral tissue. As the disturbances in nitric oxide generation and the release of endothelin-1 (ET-1) are the early signs of injury by NSAIDs, we investigated oral mucosal ulcer healing in the presence of NSAID administration by analyzing the expression of endothelin-converting enzyme-1(ECE-1), responsible for ET-1 generation, and the mucosal activity of inducible (NOS-2) and constitutive (cNOS) nitric oxide synthase responsible for nitric oxide production. Groups of rats with acetic-induced buccal mucosal ulcers were subjected twice daily for up to 10 days to intragastric administration of either indomethacin (5 mg/kg), aspirin (20 mg/kg), or the vehicle and their mucosal tissue subjected to macroacopic assessment of ulcer healing rate and biochemical measurements. While in the control group the ulcer healed by the tenth day, only a 57.2% reduction in the ulcer crater area was attained in the animals subjected to indomethacin and a 54.8% reduction in ulcer occurred in the presence of aspirin administration. Futhermore, by the tenth day, the delay in healing in the presence of indomethacin was manifested by a 4.9-fold higher rate of apoptosis, a 2.7-fold higher expression of ECE-1 activity, a 3.9-fold higher expression of NOS-2 activity and a 2.2-fold decline in cNOS activity, while the interference in ulcer healing by aspirin was characterized by a 5.6-fold higher rate of apoptosis, a 2.8-fold expressiom of ECE-1 activity, a 3.7-fold higher expression of NOS-2 activity and a 2.3-fold lower expression of cNOS activity. Our findings demonstrate that NSAIDs not only pose a well-known risk of gastrointestinal injury, but also interfere with soft oral tissue repair. The impairment in buccal mucosal ulcer healing by NSAID ingestion is manifested in up-regulation in the expression of ECE-1 responsible for ET-1 generation, suppression in cNOS, and amplification of apoptotic events that delay the healing process.     

Induction of endothelin-converting enzyme-1 in gastric mucosal injury by idomethacin

Endothelin-1 (ET-1) is a 21-amino acid vasoactive peptide produced from a 39-amino acid biologically inactive peptide, big ET-1, by the action of endothelin-converting enzyme-1 (ECE-1). We investigated gastric mucosal expression of ECE-1 during a 16 h course of inflammatory responses associated with gastric mucosal injury caused by indomethacin. The extent of gastric mucosal damage reached a maximum 4 h following the drug, and was accompanied by a 3.9-fold enhancement in the expression of ECE-1 activity and a significant elevation in ET-1 (4.5-fold), TNF-alpha (11.3-fold), and apoptosis (29.9-fold). A 37.2% decrease in the severity of lesion 16 h following the drug was associated with a 44.5% reduction in the mucosal expression of ECE-1 activity and a decline in TNF-alpha (64%), ET-1 (65.2%), and apoptosis (72.3%). The results demonstrate that gastric mucosal injury by indomethacin is associated with up-regulation of ECE-1 expression, which leads to the enhancement of ET-1 production, induction of TNF-alpha, and triggering apoptotic events that disrupt gastric mucosal homeostasis.     

Involvement of endothelin-1 in up-regulation of gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide

In this study, we investigated gastric mucosal inflammatory responses during Helicobacter pylori lipopolysaccharide-induced gastritis by analyzing the interplay between mucosal expression of endothelin-1 (ET-1), interleukin-4 (IL-4) and tumor necrosis factor-alpha (TNF-alpha). The assays conducted 4 days after intragastric dose of H. pylori lipopolysaccharide demonstrated a pattern of acute mucosal reaction characterized by the inflammatory infiltration of the lamina propria, hyperemia, and epithelial hemorrhage. This was accompanied by a 3.1-fold increase in the mucosal expression of ET-1 and a 9-fold enhancement in TNF-alpha, while the level of IL-4 showed a 20.8% decline. The results implicate ET-1 in gastric mucosal responses to H. pylori, and suggest that an increase in its level, combined with a loss of compensatory action by IL-4, may be responsible for the induction of TNF-alpha and triggering apoptotic events that exacerbate the inflammatory process.     

Gastric mucosal protection by sucralfate involves phosphoinositides participation

1. The mechanism of gastroprotective action of an antiulcer drug, sucralfate, was investigated. Studies in vivo were conducted with groups of rats with and without indomethacin pretreatment, and the animals received sucralfate followed by ethanol. In the in vitro system, gastric mucosa was cultured in the presence of sucralfate with and without indomethacin. 2. The in vivo experiments revealed that ethanol caused extensive gastric lesions which were significantly reduced following sucralfate pretreatment. Furthermore, sucralfate was also capable of preventing the detrimental effect of indomethacin on gastric mucus gel dimension and its mucin content. 3. The data with gastric mucosal culture showed that the sucralfate elicited increase in mucin was accompanied by the enhanced turnover of mucosal phosphoinositides. 4. Regardless of the inclusion of indomethacin, sucralfate evoked 23% reduction in phosphatidylinositol, 24% increase in inositol-1-phosphate and 3.4-fold increase in inositol-1,4,5-trisphosphate, thus indicating the activation of phosphoinositide-specific phospholipase C. 5. The results demonstrate that the gastric mucosal protective action of sucralfate is not mediated by endogenous prostaglandins, but appears to involve the metabolism of phosphoinositide-derived messenger molecules.     

Differences in action of topical and systemic cysteamine on gastric blood flow,gastric acid secretion and gastric ulceration in the rat

The effect of cysteamine on gastric blood flow and on the indomethacin-induced gastric mucosal damage was studied. In anesthetized rats, cysteamine (280 mg/kg) given subcutaneously (sc) decreased gastric blood flow measured by the laser Doppler flowmetry technique. In contrast, cysteamine (1–60 mg/ml) applied topically to the serosal surface of the stomach evoked a concentration-dependent and long-lasting increase in gastric blood flow. At 60 mg/ml, cysteamine increased blood flow by 166.8 ± 26.1% of predrug control value. Pretreatment with indomethacin (20 mg/kg, sc), intravenous (iv) atropine (1 mg/kg), propranolol (1 mg/kg, iv), combined H₁ and H₂-blockade or bilateral cervical vagotomy alone or combined with iv guanethidine (8 mg/kg), or pretreatment with the capsaicin analogue resiniferatoxin did not reduce the vasodilator response to cysteamine. The vasodilator response to topical capsaicin, was not reduced after sc cysteamine (280 mg/kg) pretreatment. In conscious pylorus-ligated rats, sc cysteamine (100 or 280 mg/kg) given simultaneously with indomethacin inhibited gastric acid output but had variable effects on the indomethacin-induced gastric mucosal damage. Cysteamine (100 or 280 mg/kg) administered sc 4 h prior to indomethacin enhanced gastric injury by sc indomethacin, but did not prevent the gastroprotective action of capsaicin. In contrast, orally administered cysteamine (60 mg/ml) reduced gastric injury induced by sc indomethacin plus intragastric HCl. These data provide the first evidence for the effect of cysteamine on gastric microcirculation in the rat and suggest a direct vasodilator effect for topical cysteamine. The microvascular effects of cysteamine are largely responsible for the different effects of this agent on experimental gastric injury.     

Role of endothelin-1 and interleukin-4 in buccal mucosal ulcer healing: effect of chronic alcohol ingestion

We investigated the effect of chronic alcohol ingestion on buccal mucosal ulcer healing by analyzing the interplay between mucosal expression of tumor necrosis factor-alpha (TNF-alpha), endothelin-1 (ET-1), and interleukin-4 (IL-4). Chronic ulceration was induced in rats maintained for 5 weeks on alcohol-containing or control liquid diet. In both groups, the ulcer onset was characterized by a massive increase (6.5-8.9-fold) in TNF-alpha and ET-1 (1.6-4.0-fold), and a decrease (1.4-1.5-fold) in IL-4. However, the group on the alcohol diet exhibited a 38.3% higher mucosal expression of TNF-alpha, a 26. 2% higher ET-1 level, and a 6.5% lower content of IL-4. While in both groups the ulcer healing was accompanied by an increase in buccal mucosal expression of IL-4, and a decline in ET-1 and TNF-alpha, the changes were significantly slower in the alcohol diet group and manifested by a 4 day delay in ulcer healing. The results suggest that chronic alcohol ingestion exerts detrimental effects on the buccal mucosal IL-4 expression, causing dysregulation of ET-1 production, induction of TNF-alpha, and triggering apoptotic events that delay the mucosal repair.     

Gastroprotective effect of epoxy clerodane diterpene isolated from Tinospora cordifolia Miers (Guduchi) on indomethacin-induced gastric ulcer in rats

The present study evaluated the gastroprotective effect of epoxy clerodane diterpene (ECD), isolated from Tinospora cordifolia on indomethacin-induced gastric ulcer in rats. Administration of indomethacin exhibits extreme levels of ulcer index (UI) and myeloperoxidase (MPO) activity. Indomethacin down regulated PGE₂, anti-inflammatory cytokines (IL-4, IL-10) and pro-angiogenic factors (VEGF and EGF). The ECD pretreatment considerably increased the levels of PGE₂, anti-inflammatory cytokines and pro-angiogenic factors. The ulcer-healing activity of ECD was inhibited by pre-administration of the specific COX-1 inhibitor (SC560) and nonspecific NOS inhibitor (l-NAME), which indicates the involvement of PGE₂ and NOS in ECD induced ulcer healing activity. These findings suggest that ECD exerts its antiulcer activity by reinforcement of defensive elements and diminishing the offensive elements.     

Gastroprotective and Anti-oxidative Properties of Ascorbic Acid on Indomethacin-induced Gastric Injuries in Rats

Reactive oxygen species (ROS) have been implicated in the etiology of indomethacin-induced gastric mucosal damage. This study investigated ascorbic acid (vitamin C)'s protective effects against oxidative gastric mucosal damage induced by indomethacin. Ascorbic acid is a powerful antioxidant because it can donate a hydrogen atom and form a relatively stable ascorbyl free radical. We have investigated alterations in the levels of myeloperoxidase, antioxidant system enzymes (glutathione S-transferase, superoxide dismutase, glutathione reductase, catalase, glutathione peroxidase), lipid peroxidation and glutathione, as markers for ulceration process following oral administration of ascorbic acid, famotidine, lansoprazole, and ranitidine in rats with indomethacin-induced ulcers. In the present study, we found that (1) ascorbic acid, famotidine, lansoprazole and ranitidine reduced the development of indomethacin-induced gastric damages; (2) the administration of indomethacin caused a significant decrease in the levels of superoxide dismutase, glutathione peroxidase, glutathione S-transferase and glutathione, and an increase in the lipid peroxidation level; (3) the administration of ascorbic acid reversed the trend, inducing a significant increase of these enzymes' levels and a reduction in lipid peroxidation level in tissues; and (4) catalase, glutathione reductase and myeloperoxidase activities, increased by indomethacin, were found to be lower in the ascorbic acid, famotidine, lansoprazole and ranitidine-treated groups. The results indicate that the gastroprotective properties of ascorbic acid could be related to its positive effects on the antioxidant system and myeloperoxidase activity in indomethacin-induced gastric ulcers in rats.     

Gastroprotective action of glucocorticoids during the formation and the healing of indomethacin-induced gastric erosions in rats.

The aim of the present study consisted of the investigation of glucocorticoid role in the formation and the healing of indomethacin-induced (25 mg/kg, s.c.) gastric erosions in rats. The effect of deficiency of glucocorticoid production followed by corticosterone replacement on the formation and the healing of the gastric erosions was evaluated. Glucocorticoid production was decreased by adrenalectomy or by delayed inhibitory action after a single pharmacological dose of cortisol (300 mg/kg i.p.) injected 1 week before the onset of ulcerogenic stimulus. Indomethacin induced corticosterone rise and caused gastric erosions. The loss of indomethacin-induced plasma corticosterone rise potentiated the formation of indomethacin-induced erosions in both models. The area of gastric erosions in rats with glucocorticoid deficiency was considerably larger than that in control animals 4 h after indomethacin administration as well as during 48 h after the drug administration (period of erosion healing). Injecting corticosterone in rats with glucocorticoid deficiency significantly decreased the formation of indomethacin-induced gastric erosions and promoted their healing. Thus, the present data support the gastroprotective action of glucocorticoids in the formation and in the healing of indomethacin-induced mucosal injury.     

Oxidative stress involvement and gene expression in indomethacin-induced gastropathy

It has been proposed that neutrophil- and oxygen radical-dependent microvascular injuries are important prime events that lead to gastric mucosal injury induced by indomethacin. Reactive oxygen species (ROS) produced by activated neutrophils after indomethacin treatment cause gastric mucosal injury via ROS-mediated oxidation of important biomolecules such as lipid, protein, and DNA. In addition, it has been revealed that indomethacin-induced gastric mucosal injury occurs via gastric epithelial cell apoptosis. However, there is little known about the mechanism of indomethacin-triggered cellular response and apoptotic signaling in gastric mucosal cells. In the present study, we summarize the evidence that supports the involvement of oxidative stress and apoptosis in indomethacin-induced gastropathy, and review the gene expression profiles of gastric epithelial cells after indomethacin treatment determined by DNA microarray analysis.     

Role of basic fibroblast growth factor in the suppression of apoptotic caspase-3 during chronic gastric ulcer healing.

BACKGROUND: In the course of ulcer healing an array of factors compel mucosal cells to proliferate, differentiate, and migrate to the site of injury. The recognition of triggering cues requires close interaction between the regulatory proteins integrating the growth factor and cytokine- mediated signals that propel cells through the cycle events, or to signal apoptosis. In this study, we analyzed the interplay between mucosal expression of the receptor-bound basic fibroblast growth factor (bFGF-R) and cyclin-dependent kinase (Cdk2), and the activity of apoptotic protease, caspase-3, and constitutive nitric oxide synthase (cNOS) during chronic gastric ulcer healing. METHODS: The experiments were conducted with gastric mucosa of rats at different stages of acetic acid-induced chronic gastric ulcer healing. RESULTS: The ulcer onset (2 days following injury) was characterized by a massive epithelial apoptosis associated with a 33-fold increase in caspase-3 activity and a 7.6-fold drop in cNOS, while the mucosal expression of Cdk2 fell by an 18% and that of bFGF-R by 12%. The ulcer healing was accompanied by a rapid elevation in bFGF-R and Cdk2, and a slow recovery in cNOS activity, while the caspase-3 activity and epithelial apoptosis showed a marked decline. The bFGF-R and Cdk2 reached their maximums of 2.2-2.3-fold at 4-6 day of healing, while the caspase-3 activity and the apoptotic DNA fragmentation showed a 3-fold decline by the 7th day of healing. However, the activity of cNOS remained about 50% lower than that of the controls. CONCLUSIONS: Taken together, these results provide strong indications that the initial phase of ulcer healing involves the inhibition of apoptotic caspase activities by a signaling events initiated by bFGF-receptor activation and propagated by the regulatory kinases that propel the cell cycle progression. Our findings also point towards participation of cNOS in the suppression of proapoptotic activities in gastric mucosa.     

Oxidative stress involvement and gene expression in indomethacin-induced gastropathy

Abstract

It has been proposed that neutrophil- and oxygen radical-dependent microvascular injuries are important prime events that lead to gastric mucosal injury induced by indomethacin. Reactive oxygen species (ROS) produced by activated neutrophils after indomethacin treatment cause gastric mucosal injury via ROS-mediated oxidation of important biomolecules such as lipid, protein, and DNA. In addition, it has been revealed that indomethacin-induced gastric mucosal injury occurs via gastric epithelial cell apoptosis. However, there is little known about the mechanism of indomethacin-triggered cellular response and apoptotic signaling in gastric mucosal cells. In the present study, we summarize the evidence that supports the involvement of oxidative stress and apoptosis in indomethacin-induced gastropathy, and review the gene expression profiles of gastric epithelial cells after indomethacin treatment determined by DNA microarray analysis.     

Suppression of caspase-3 and nitric-oxide synthase-2 during buccal mucosal ulcer healing: effect of chronic alcohol ingestion

In this study, we analyzed the effect of chronic alcohol ingestion on the expression of constitutive (cNOS) and inducible (NOS-2) nitric-oxide synthase and the activity of an apoptotic protease, caspase-3, during buccal mucosal ulcer healing in rats maintained for 5 weeks on alcohol-containing or control liquid diet. In comparison with the controls, the ulcer onset in the alcohol group was characterized by a 2.5-fold greater epithelial cells apoptosis, 2.1-fold greater expression of caspase-3 activity, and a 1.4-fold greater enhancement in NOS-2, but expression of cNOS showed a 1.3-fold decrease. In both groups the ulcer healing was accompanied by a gradual decline in apoptosis, caspase-3, and NOS-2 and a recovery in cNOS activity, but the changes were considerably slower in the alcohol diet group, as manifested by a 40%(4 days) delay in ulcer healing. These results suggest that chronic alcohol ingestion interferes with the suppression of NOS-2 and the apoptotic events propagated by caspase-3 and hence affects the efficiency of oral mucosal repair process.     

Thioredoxin-1 attenuates indomethacin-induced gastric mucosal injury in mice

Indomethacin is one of non-steroidal anti-inflammatory drugs that are commonly used clinically and often cause gastric mucosal injury as a side effect. Generation of reactive oxygen species (ROS) and activation of apoptotic signaling are involved in the pathogenesis of indomethacin-induced gastric mucosal injury. Thioredoxin-1 (Trx-1) is a small redox-active protein with anti-oxidative activity and redox-regulating functions. The aim of this study was to investigate the protective effect of Trx-1 against indomethacin-induced gastric mucosal injury. Trx-1 transgenic mice displayed less gastric mucosal damage than wild type (WT) C57BL/6 mice after intraperitoneal administration of indomethacin. Administration of recombinant human Trx-1 (rhTrx-1) or transfection of the Trx-1 gene reduced indomethacin-induced cytotoxicity in rat gastric epithelial RGM-1 cells. Pretreatment with rhTrx-1 suppressed indomethacininduced ROS production and downregulation of phosphorylated Akt in RGM-1 cells. Survivin, a member of inhibitors of apoptosis proteins family, was downregulated by indomethacin, which was suppressed in Trx-1 transgenic mice or by administration of rhTrx-1 in RGM-1 cells. Trx-1 inhibits indomethacin-induced apoptotic signaling and gastric ulcer formation, suggesting that it may have a preventive and therapeutic potential against indomethacin-induced gastric injury.     

The role of glucocorticoids in healing of indomethacin-induced lesions in the rat gastric mucosa

Pretreatment with a single large dose of cortisol a week before indomethacin administration, or an adrenalectomy induced a glucocorticoid production deficiency in rats. The area of gastric erosions in these rats was considerably larger than in the control animals in 4, 24, and 48 hours after the indomethacin administration. Administration of corticosterone noticeably prompted the healing of the erosions in the rats with glucocorticoid deficiency. The findings suggest a gastroprotective effect of glucocorticoids in healing of indomethacin-induced mucosal injury.