Biomedical subjects

A Slomiany

Publications and source records attributed to A Slomiany.

At least 37 records · Page 2Linked to original sources

PubMed2000

Suppression of endothelin-converting enzyme-1 during buccal mucosal ulcer healing: effect of chronic alcohol ingestion.

Among the factors affecting the efficiency of soft oral tissue healing is endothelin-1 (ET-1), a potent vasoactive peptide produced from a biologically inactive big ET-1 by the action of endothelin-converting enzyme-1 (ECE-1). We investigated the expression of ECE-1 during buccal mucosal ulcer healing in rats maintained for 5 weeks on alcohol containing or control diet. The mucosal activity of ECE-1, characterized by sensitivity to phosphoramidon, was associated with microsomal fraction and showed an elevated (3.1-fold) level in the alcohol diet group. Moreover, the ulcer onset in the alcohol group was reflected in a 39% greater expression of ECE-1 activity, and was accompanied by a 1.4-fold greater increase in TNF-alpha and a 2.5-fold greater enhancement in epithelial cell apoptosis. While in both groups the ulcer healing was associated with a decrease in buccal mucosal expression of ECE-1, as well as a decline in TNF-alpha and apoptosis, the changes were significantly slower in the alcohol diet group and manifested by a 40% delay in healing. Thus, chronic alcohol ingestion leads to up-regulation of ECE-1 expression, induction of TNF-alpha, and triggering apoptotic events that delay the mucosal repair.

Animals↗

PubMed2000

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.

Animals↗

PubMed2000

Up-regulation of endothelin-converting enzyme-1 in gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide.

Endothelin-1 (ET-1) is a vasoactive peptide produced from a biologically inactive big ET-1 by the action of endothelin-converting enzyme-1 (ECE-1). We investigated gastric mucosal expression of ECE-1 during a 10-day course of inflammatory responses associated with acute gastritis elicited by Helicobacter pylori lipopolysaccharide. The ECE-1 activity was associated with microsomal fraction and the level of its expression reflected the extent of mucosal inflammatory involvement. The histologic pattern of inflammation reached a maximum on the 4th day following the lipopolysaccharide and was accompanied by a 4.1-fold enhancement in the expression of ECE-1 activity and a significant elevation in ET-1 (3.1-fold), TNF-alpha (8.8-fold), and apoptosis (11.6-fold). A 41.5% decrease in the severity of mucosal inflammation by the 10th day following the lipopolysaccharide was reflected in a 62.3% reduction in the mucosal expression of ECE-1 and a decline in TNF-alpha, ET-1, and apoptosis. Thus, H. pylori infection causes up-regulation of gastric mucosal ECE-1 expression, which leads to the enhancement of ET-1 production, induction of TNF-alpha, and triggering the apoptotic events that exacerbate the inflammatory process.

Animals↗

PubMed2000

Role of endothelin-converting enzyme-1 in the suppression of constitutive nitric oxide synthase in rat gastric mucosal injury by indomethacin.

BACKGROUND: Disturbances in nitric oxide generation and the release of a vasoactive peptide, endothelin-1 (ET-1), are well recognized early events in pathogenesis of NSAID-induced gastropathy. In this study using phosphoramidon, a potent inhibitor of endothelin-converting enzyme-1 (ECE-1), we investigated the influence of ET-1 on the expression of constitutive (cNOS) and inducible nitric oxide synthase (NOS-2) during gastric mucosal injury caused by indomethacin. METHODS: The experiments were conducted with groups of rats pretreated intragastrically with phosphoramidon (10, 20, and 40 mg/kg) or vehicle, followed 30 min later by an intragastric dose of indomethacin (60 mg/kg). The animals were killed 4 h later and their mucosal tissue subjected to macroscopic damage assessment and biochemical measurements. RESULTS: In the absence of phosphoramidon, indomethacin caused extensive multiple hemorrhagic lesions of glandular mucosa, accompanied by a 29.9-fold increase in epithelial cell apoptosis, a 13.3-fold increase in NOS-2 and a 5.5-fold decline in the activity of cNOS, while the mucosal expression of ECE-1 activity increased 4-fold and the level of ET-1 showed a 4.8-fold increase. Pretreatment with phosphoramidon produced dose-dependent reduction in the extent of mucosal damage caused by indomethacin, accompanied by a significant recovery in the expression of cNOS, and a marked decline in ECE-1, epithelial cell apoptosis and the mucosal level of ET-1. Phosphoramidon, however, had no effect on the indomethacin-induced increase in the mucosal expression of NOS-2. CONCLUSIONS: The results suggest that suppression of ET-1 generation counters the mucosal drop in cNOS and the extent of gastric mucosal damage caused by indomethacin, but has no effect on the mucosal responses associated with up-regulation of NOS-2 expression. Hence, only cNOS plays a role in the protection of gastric mucosa against damage by NSAIDs.

Animals↗

PubMed2000

Aspirin ingestion impairs oral mucosal ulcer healing by inducing membrane-bound tumor necrosis factor-alpha release.

Among the early manifestations of impairment by nonsteroidal anti-inflammatory drugs in mucosal tissue repair is the enhancement in tumor necrosis factor-alpha (TNF-alpha). We investigated the effect of aspirin ingestion on the processing of TNF-alpha in rat soft oral tissue during buccal ulcer healing. While in the control group, the ulcer healed by the 10th day; only a 54.8% reduction in the ulcer area was attained in the presence of aspirin administration. Moreover, by the 10th day, the delay in ulcer healing by aspirin was manifested in a 5.6-fold higher rate of apoptosis and a 5.2-fold higher level of soluble TNF-alpha, yet the expression of membrane-bound TNF-alpha showed a 38% decline. Treatment with metalloprotease inhibitor, Zincov, produced dose-dependent reduction (56.9%) in aspirin-induced increase in the mucosal expression of soluble TNF-alpha, evoked a 62% decrease in the rate of epithelial cell apoptosis, and led to a marked reversal (56.9%) in aspirin-induced delay in ulcer healing. Our findings indicate that the impairment in buccal ulcer healing by aspirin is a result of upregulation in the processing of soluble TNF-alpha from its membrane-bound precursor that leads to the amplification of apoptotic events and potentiation of the mucosal inflammatory responses that interfere with healing process.

Acetic Acid↗

PubMed2000

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.

Animals↗

PubMed2000

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.

Acute Disease↗

PubMed2000

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.

Animals↗

PubMed2000

Impact of ethanol on innate protection of gastric mucosal epithelial surfaces and the risk of injury.

Earlier investigations on the effect of ethanol on synthesis and posttranlational glycosylation of gastric mucus glycoprotein (mucin) revealed quantitative changes in the apoprotein assembly, glycosylation, and mucin retention on the mucosal surface (Slomiany et al.., Alcoholism: Clin. Exp. Res. 21, 417-423, 1998). To assess whether metabolic consequences of ethanol ingestion, documented in the in vitro system are also occurring in vivo the rats were subjected to 8 weeks of ethanol containing liquid diet. The retention of mucin on the surface of gastric mucosa was quantitated by measuring the binding of gastric mucin to Mucin Binding Protein (MBP) of gastric mucosa. The results were compared with those obtained with the rats subjected to pair-feeding the isocaloric-control diet. Before alcohol administration, and in two weeks' intervals thereafter, the gastric contents from the animals was collected and mucin purified. After 8 weeks of the respective diet, the animals were sacrificed and their gastric mucosa used for MBP preparation. The binding of mucin to MBP before ethanol, and after 2, 4, 6, and 8 weeks of ethanol diet was quantitated with Enzyme Linked Lectin Assay (ELLA). The study with standard mucin revealed that binding of mucin to MBP differs substantially between individual animals. The same variability in binding was observed with the individual mucin preparations collected at the onset of the experiment. However, with the progression of ethanol feeding, the mucin samples besides displaying the variable and animal-specific binding to MBP at the initiation of the experiment, also showed a dramatic decrease in binding. In five animals, after two weeks of ethanol diet, mucin binding to MBP decreased by 50%; in two animals, the drastic decrease in binding was observed in mucin collected after four weeks of alcohol feeding; and in one animal a 20% decrease in binding persisted for six weeks, and then decreased to 50% in the last collection. Also, in two animals, the mucin collected after 8 weeks of ethanol feeding retained only 6-9% of the initial binding capacity. In contrast, in pair-fed controls, the mucin binding to MBP remained the same or increased up to 20%. Results of the studies, performed on mucin of the individual animals and matching preparations of MBP, showed that each animal expresses different degree of mucin binding. Moreover, in chronic ethanol ingestion, the individual variations are accompanied by a decrease in mucin binding to MBP. Since the observed decrease in binding occurred in samples containing the same preparation of MBP, the component affected by alcohol resides on mucin. Thus, considering the in vitro impact of ethanol on generation of carbohydrate chains in Golgi, and the finding on mucin oligosaccharides-dependent mucin-MBP complex formation, we conclude that ethanol impairs the synthesis of mucin oligosaccharide structures required for binding with MBP, and the retention on gastric mucosal surfaces.

Alcohol Drinking↗

PubMed1999

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.

Animals↗

PubMed1999

Gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide: down-regulation of nitric oxide synthase-2 and caspase-3 by sulglycotide.

We applied the animal model of H. pylori lipopolysaccharide-induced gastritis to assess the effect of antiulcer agent, sulglycotide, on the mucosal inflammatory responses by analyzing the interplay between the activity of a key apoptotic caspase, caspase-3, epithelial cell apoptosis, and the expression of constitutive (cNOS) and inducible (NOS-2) nitric oxide synthase. H. pylori lipopolysaccharide applied intragastrically elicited within 4 days a pattern of mucosal responses resembling that of acute gastritis. 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 2.2-fold decline in cNOS, and a 5.4-fold increase in caspase-3 activity. Treatment with sulglycotide led to a 56.7% reduction in the extent of mucosal inflammatory changes elicited by H. pylori lipopolysaccharide and an 88.3% decrease in the epithelial cells apoptosis. Furthermore, this effect of sulglycotide was associated with a 51% decrease in mucosal expression of caspase-3 activity, a 73.7% decline in NOS-2, and a 64.1% increase in cNOS. The findings suggest that sulglycotide suppresses the H. pylori-induced mucosal inflammatory responses by up-regulating cNOS and interfering with the events propagated by NOS-2 and caspase-3.

Acute Disease↗

PubMed1999

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.

Animals↗

PubMed1999

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.

Acetic Acid↗

PubMed1999

Suppression of gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide by sulglycotide.

The effect of the antiulcer agent sulglycotide on gastric epithelial cell apoptosis and the expression of tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4) during Helicobacter pylori lipopolysaccharide-induced acute gastritis was investigated. Rats, pretreated twice daily for 3 consecutive days with sulglycotide at 200 mg/kg or vehicle, were subjected to surface epithelial application of H. pylori lipopolysaccharide (50 microg/animal), and, after 4 additional days on the drug or vehicle regimen, their mucosal tissue was used for histologic assessment, quantitation of TNF-alpha and IL-4, and the assay of epithelial cell apoptosis. In the absence of sulglycotide, H. pylori lipopolysaccharide caused acute mucosal responses manifested by the inflammatory infiltration of the lamina propria with lymphocytes and plasma cells, edema, hyperemia, and epithelial hemorrhage. These responses were accompanied by an 11-fold increase in epithelial cell apoptosis and a 9-fold enhancement of the mucosal expression of proinflammatory cytokine TNF-alpha. However, the mucosal expression of regulatory cytokine IL-4 decreased by 15%. Treatment with sulglycotide produced significant (56.6%) reduction in the extent of acute mucosal inflammatory changes caused by H. pylori lipopolysaccharide. Moreover, the effect of sulglycotide was manifested in an 88.3% reduction in the epithelial cell apoptosis and a 69.1% decrease in the mucosal expression of TNF-alpha, whereas the expression of IL-4 showed only marginal (6%) enhancement. The results suggest that the cytoprotective agent sulglycotide suppresses the inflammatory and apoptotic events elicited in gastric mucosa by H. pylori lipopolysaccharide through stimulation of TNF-alpha expression.

Animals↗

PubMed1999

Activation of apoptotic caspase-3 and nitric oxide synthase-2 in gastric mucosal injury induced by indomethacin.

BACKGROUND: Apoptosis is the process of programmed cell death characterized by a series of distinct biochemical and morphologic changes involving activation of the caspase protease, cascade, which remains under the regulatory control of nitric oxide. In this study we investigated the activity of a key apoptotic protease, caspase-3, and the expression of inducible nitric oxide synthase (NOS-2) associated with gastric epithelial cell apoptosis during indomethacin-induced gastric mucosal injury. METHODS: The experiments were conducted with groups of rats subjected to intragastric administration of 60 mg/kg indomethacin or the vehicle. After 2 h the animals were killed and their gastric mucosal tissue used for macroscopic assessment, assays of epithelial cell apoptosis, and the measurement of caspase-3 and NOS-2 activities. RESULTS: Indomethacin caused extensive multiple hemorrhagic lesions accompanied by marked enhancement in epithelial cell apoptosis, a 3.9-fold increase in mucosal expression of caspase-3 activity, and an 11.9-fold induction in NOS-2. Moreover, the mucosal expression of NOS-2 showed a positive correlation with the extent of changes induced in caspase-3 activity. CONCLUSIONS: The results implicate caspase-3 in the process of indomethacin-induced gastric epithelial cell apoptosis and point towards participation of NOS-2 in the amplification of the cell death signaling cascade, hence contributing to the extent of mucosal injury.

Animals↗

PubMed1999

Role of endothelin-1 and constitutive nitric oxide synthase in gastric mucosal resistance to indomethacin injury: effect of antiulcer agents.

BACKGROUND: Endothelin-1 (ET-1) and nitric oxide, recognized key mediators implicated in the pathophysiology of gastric mucosal injury, are known to exert opposing effects on the inflammatory processes mediated by regulatory cytokines. In this study we investigated the mucosal expression of ET-1 and interleukin-4 (IL-4) and the activity of constitutive nitric oxide synthase (cNOS) during indomethacin-induced gastric mucosal injury and evaluated the effect of antiulcer agents, omeprazole and sucralfate, on this process. METHODS: The experiments were conducted with groups of rats pretreated intragastrically with omeprazole (40 mg/kg), sucralfate (200 mg/kg), or vehicle, followed 30 min later by an intragastric dose of indomethacin (60 mg/kg). The animals were killed 2 h later, and their mucosal tissue subjected to macroscopic damage assessment, ET-1 and IL-4 expression assay, and the measurement of cNOS activity. RESULTS: In the absence of antiulcer agents, indomethacin caused multiple hemorrhagic lesions and extensive epithelial cell apoptosis, accompanied by a 20.7% reduction in IL-4, a 3.1-fold increase in mucosal expression of ET-1, and a 4.2-fold decrease in cNOS. Pretreatment with a gastroprotective agent, sucralfate, produced a 59.7% reduction in the mucosal damage caused by indomethacin, a 41.2% decrease in epithelial cell apoptosis, and a 56.5% reduction in ET-1, whereas the expression of IL-4 increased by 29.3% and that of cNOS showed a 3.3-fold increase. In contrast, the pretreatment with a proton pump inhibitor, omeprazole, led to only a 10.5% reduction in the extent of mucosal damage caused by indomethacin and a 13% decrease in apoptosis, whereas the expression of cNOS increased by 68.7% and ET-1 by 12.2%, and the level of IL-4 remained essentially unchanged. CONCLUSIONS: The results suggest that an increase in the vasoconstrictive ET-1 level combined with a decrease in regulatory cytokine, IL-4, and a loss of compensatory action by cNOS may be responsible for the gastric mucosal injury caused by indomethacin. Our findings also indicate the value of sucralfate in countering the untoward gastrointestinal side effects of nonsteroidal anti-inflammatory drug therapy.

Animals↗

PubMed1999

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.

Alcohol Drinking↗

PubMed1999

Chronic ethanol-initiated apoptosis in hepatocytes is induced by changes in membrane biogenesis and intracellular transport.

The outcome of chronic ethanol consumption recorded in liver by in situ staining of the genomic DNA in fragmented nuclei indicates the course of cellular events that has been coined as apoptosis or programmed cell death. Hence, we designed the study to determine which ethanol-induced modification of the cellular make-up is responsible for the hastening the cell damage. The in vitro assays were performed with cellular organelles and cytosol prepared from hepatocytes derived from rats subjected to 9 weeks of chronic alcohol consumption. The results were compared with the pair-fed controls receiving isocaloric liquid diet. In the initial phase of the studies, we established that the process of apoptosis was not triggered by the aberrant activity of neutral or acidic sphingomyelinase. The hepatocytes derived from alcohol and control diets manifested equal enzymatic activity. The de novo synthesis of sphingoid bases and ceramides in the alcohol-derived sample of endoplasmic reticulum was reduced, but the in situ apoptosis was up to 36-fold higher than in the control. Also, the isolated hepatocytes contained a 2- to 4-fold higher amount of nucleosomal fragments in the cytosolic extracts. The endosomes from liver hepatocytes of ethanol-consuming rats, in the presence of the cytosol and mitochondria from pair-fed controls, disclosed 2 to 3 times higher apoptotic potential than sample consisting of ethanol-derived fractions only, and 3 to 5 times higher than the control-derived fractions. The substantial increase in apoptosis, as recorded in the amount of DNA fragments released to the cytosol from the fresh nuclei, was also recorded when the microsomal membranes of endoplasmic reticulum and Golgi were incubated in the conditions with preserved intracellular transport. The maximal 20-fold increase of apoptotic activity was recorded in the incubation mixtures of ethanol-derived endoplasmic reticulum-Golgi membranes with control-derived cytosol in the presence of the ATP generating system. Results infer that the intracellular transport vesicles, generated from ethanol-modified membranes in the presence of the substrates that are available in the cytosol of the control hepatocytes, activate the apoptotic activity in the in vitro system. This interpretation is supported by the results of analysis of the clathrin-coated transport vesicles that, in contrast to nonclathrin transport vesicles, contain a sizable accumulation of ceramides that are known to induce apoptosis.

Animals↗