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.     

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.     

Up-regulation of gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide by aspirin but not indomethacin

Infection with Helicobacter pylori and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are recognized as the two primary factors in the etiology of gastric disease. In this study, we applied the animal model of H. pylori-induced gastritis to assess the influence of NSAIDs on the course of mucosal inflammatory responses to H. pylori. Two days following intragastric application of H. pylori lipopolysaccharide, rats were divided into groups and administered daily for up to 8 days either indomethacin, aspirin or the vehicle, and their gastric mucosal tissue subjected to histological and biochemical assessment. H. pylori lipopolysaccharide elicited within 2 days a pattern of acute mucosal inflammatory responses accompanied by a massive epithelial cell apoptosis, and a marked increase in the expression of membrane-bound and soluble forms of TNF-alpha. 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 38.1% reduction in apoptosis, a 53.2% decline in membrane-bound TNF-alpha and a 63.8% decrease in soluble TNF-alpha. Compared to the vehicle controls, aspirin caused a 36.2% increase in the severity of the mucosal inflammatory involvement by the second day of administration and a 25.9% increase in the inflammatory involvement occurred by the 8th day; this effect of aspirin was accompanied by a significant (54.5%) induction in apoptosis, a 58.2% decline in membrane-bound TNF-alpha and a 61% increase in soluble TNF-alpha. In contrast, administration of indomethacin evoked only a marginal increase (5-7%) in apoptosis, and caused no discernible changes in the severity of gastric mucosal involvement and the expression of TNF-alpha forms elicited by H. pylori lipopolysaccharide. The findings indicate that aspirin, but not indomethacin, increases the severity of gastric mucosal inflammatory responses to H. pylori. This detrimental influence of aspirin appears to result from up-regulation in the mucosal expression of soluble form of TNF-alpha, which leads to the amplification of apoptotic events that potentiate gastric mucosal inflammatory reaction to H. pylori.     

Effects of leminoprazole, omeprazole and sucralfate on indomethacininduced delayed healing of kissing gastric ulcers in rats

We have examined whether or not repeated treatment with indomethacin delays the healing of kissing gastric ulcers induced in rats. The effects of leminoprazole, omeprazole and sucralfate on any delay in ulcer healing caused by indomethacin were also determined in relation to myeloperoxidase activity. Kissing gastric ulcers were induced by luminal application of an acetic acid solution. Indomethacin significantly delayed ulcer healing in a dose-dependent manner. Leminoprazole and omeprazole decreased the size and depth of ulcers, the healing of which was delayed by indomethacin, while sucralfate only decreased the ulcer depth. Histological studies showed that indomethacin inhibited tissue contraction and regeneration of the ulcerated mucosa. Leminoprazole and omeprazole prevented the inhibition of these parameters. The myeloperoxidase (MPO) activity of the ulcer portion in animals treated with indomethacin was markedly higher than in the control group. Both leminoprazole and omeprazole, but not sucralfate, significantly reduced MPO activity in contrast to the control value (in the presence of indomethacin). There was a significant relationship between the ulcerated area and myeloperoxidase activity. These results suggested that: (i) leminoprazole and omeprazole prevent the indomethacin-induced delay in ulcer healing by promoting tissue contraction and regeneration of the ulcerated mucosa; (ii) sucralfate prevents the indomethacin-induced delay in ulcer healing via the promotion of the formation of granulation tissue; and (iii) MPO activity will be useful to biochemically ensure the healing state of ulcers.     

Functional Mechanism Underlying COX-2 Expression Following Administration of Indomethacin in Rat Stomachs: Importance of Gastric Hypermotility

The expression of COX-2 is up-regulated in the rat stomach after administration of indomethacin, and the inhibition of this enzyme may be a key to NSAID-induced gastric damage. The present study investigated the mechanism for COX-2 expression induced in the rat stomach by indomethacin, in relation with the ulcerogenic processes. The animals were given indomethacin or SC-560 p.o., and the gastric mucosa was examined 8 hr later. Indomethacin decreased the mucosal PGE2 content and produced gross damage with gastric hypermotility and the expression of COX-2 mRNA in the mucosa. Although SC-560 did not produce damage, this agent caused a decrease in the PGE2 content and an increase in gastric motility as well as the up-regulation of COX-2 expression, and provoked damage in the presence of rofecoxib. Gastric lesions induced by indomethacin were prevented by both atropine (even in the presence of exogenous HCl) and omeprazole, although the hypermotility response was inhibited only by atropine. The COX-2 expression induced by indomethacin or SC-560 was inhibited by atropine, even in the presence of exogenous HCl, while omeprazole had no effect. The mucosal PGE2 content was decreased by SC-560 at 2 hr but recovered 8 hr later, and this recovery of PGE2 was attenuated by both atropine and rofecoxib but not omeprazole. These results suggested that the COX-2 expression in the stomach following treatment with indomethacin is functionally associated with gastric hypermotility response induced by COX-1 inhibition. Luminal acid does not play a role in the up-regulation of COX-2 expression in the stomach following administration of indomethacin.     

Effect of Sucralfate on the Degradation of Human Gastric Mucus by Helicobacter pylori Protease and Lipases

Among the factors implicated in the weakening of mucus perimeter of gastric mucosal defense is Helicobacter pylori, the pathogenic action of which appears to be exerted through the elaborated protease and lipase enzymes. We present evidence that the activities of these enzymes are inhibited by an antiulcer agent, sucralfate. The grown colonies of bacteria were washed with saline, filtered through sterilization filter, and the filtrate used as the enzyme source. In the absence of sucralfate, the H. pylori protease caused extensive degradation of human gastric mucus protein, whereas free fatty acids, glycerol monooleate and lysophatidylcholine, were produced by the action of H. pylori lipase and phospholipase A enzymes. Introduction of sucralfate to the incubation systems led to the reduction in the rate of mucus protein and lipid degradation. The rate of proteolysis inhibition was proportional to sucralfate concentration up to 90 micrograms/ml, at which point a 32.5% reduction in mucus degradation was obtained, whereas the maximum inhibition of lipase (35.5%) and phospholipase A (48%) activities occurred at sucralfate concentration of 200 micrograms/ml. The results demonstrate that sucralfate is capable of counteracting in vitro the mucolytic activity of H. pylori toward human gastric mucus proteins and lipids.     

Adhesive Effect of Ecabet Sodium in a Porcine Gastric Leer Model

Abstract: Protection of the gastric mucosa, based on its high affinity for mucosal lesions, has been reported as one of the antiulcer effects of ecabet sodium. We investigated the adhesive effect of this drug on mucosal lesions in a porcine gastric ulcer model (freshly isolated stomach) and on human mucosal lesions resulting from endoscopic gastric mucosal resection (EMR) and polypectomy. After ulcer lesions had been induced by EMR in the isolated porcine stomach, ecabet sodium and sucralfate suspensions were applied. After washing with citrate buffer, at a pH of 1, 3 or 5, the adhesion of each drug to the gastric mucosa was measured. At pH 1, both drugs showed satisfactory adhesion to the ulcer lesions. When the acidity of the ulcer surfaces was decreased to pH 3 and then to pH 5, the adhesion of sucralfate showed a marked decrease (100%→31→% 13%). while that of ecabet sodium showed only a slight decrease (100%→75%→64%). Futhermore, the activity of thrombin in the ecabet sodium suspension remained high at pH 1, 3 and 5. Since the ecabet sodium suspension produced a satisfactory covering effect on gastric mucosal lesions and this effect was maintained even at low acidity, this drug is considered suitable for endoscopic directsprinkling therapy for gastric mucosal lesions.     

Role of gastric mucosal blood flow in cytoprotection

We compared the effects of graded doses of misoprostol (50-200 mg), omeprazole (12.5-50 mg), cimetidine (6.25-50 mg) and sucralfate (50-200 mg) on gastric mucosal blood flow as measured by laser Doppler flowmetry and gastric mucosal injury induced by ethanol. The results demonstrated that sucralfate, misoprostol and omeprazole, but not cimetidine, increased gastric mucosal blood flow in a dose-dependent manner and protected the mucosa against ethanol damage. The peak and summation blood flow were significantly greater with sucralfate than with misoprostol and omeprazole, but the degree of mucosal protection was similar. These results indicate that the increase in gastric mucosal blood flow, an action which is common to the three drugs, plays an important role in gastric mucosal protection, but other factors are also involved.     

The effect of misoprostol, omeprazole and sucralfate on nicotine- and ethanol-induced gastric injury and gastric mucosal blood flow: A comparative study

Nicotine, which is thought to be responsible for part of the pharmacological effect of smoking, exacerbates gastric mucosal injury in rats. The effects of misoprostol (12.5 micrograms to 100 micrograms), omeprazole (12.5 mg to 100 mg) and sucralfate (50 to 400 mg) on gastric mucosal blood flow and mucosal injury induced by nicotine were studied in an ex vivo gastric chamber preparation in rats. Rats were pretreated with nicotine (25 micrograms/mL orally) for 10 days and ethanol was added to the gastric chamber preparation. Laser Doppler flowmetry was used to measure the gastric mucosal blood flow and mucosal damage (ulcer index) was assessed by the area of haemorrhagic lesions. The ulcer index was significantly higher in rats pretreated with nicotine. Treatment with misoprostol and omeprazole lowered the ulcer index significantly compared with controls. The peak and summation blood flows were lower in nicotine-treated rats but failed to reach statistical significance. The peak blood flow (blood flow at 45 min) and the summation blood flow were significantly higher with all doses of sucralfate, misoprostol and omeprazole than in controls (P less than 0.05). The increase in gastric mucosal blood flow was significantly higher with sucralfate and misoprostol than with omeprazole. We conclude that sucralfate, misoprostol and omeprazole prevent nicotine- and ethanol-induced gastric mucosal damage and are accompanied by an increase in gastric mucosal blood flow. This indicates that smoking exacerbates gastric mucosal injury and that cytoprotective and site-protective agents can reduce injury by these noxious agents.     

Treatment of the gastric stump ulcer: an open study with five drugs

BACKGROUND/AIMS: Despite a great progress in the treatment of peptic ulcer disease, the management of gastric stump ulcers still remains to be established. METHODOLOGY: Eighty-one patients with peptic ulcer developed postoperatively in the gastric remnant were treated in an open trial with 5 antiulcer drugs (cimetidine, omeprazole, sucralfate, colloidal bismuth and misoprostol) characterized by different mechanisms of action. The ulcer healing rate was evaluated endoscopically after 2, 4 and 6 weeks. RESULTS: It was found that after 2 weeks the most rapid ulcer healing was in the omeprazole and cimetidine treated groups, 67 and 43% of healing, respectively. Also after 4 weeks the antisecretors were more effective than gastroprotective drugs; ulcer healing rate for omeprazole was 87% and cimetidine 68%, while for sucralfate, colloidal bismuth and misoprostol 50%, 52%, and 33%, respectively. After 6 weeks all drugs represented very close ulcer healing rates. CONCLUSIONS: Both antisecretory and gastroprotective drugs may be useful in the management of stump ulcers, however, to initiate and accelerate the stump ulcer healing omeprazole appears to be the drug of choice.     

Protection against alcohol-induced gastric mucosal injury by geranylgeranylacetone: effect of indomethacin

The mechanism of gastric mucosal protection by an antiulcer agent, geranylgeranylacetone (GGA), against ethanol-induced injury was investigated. The experiments were conducted with groups of rats with and without intraperitoneal indomethacin pretreatment. Animals received intragastrically either a dose of GGA (200 mg/kg) or a vehicle, followed 30 min later by 1 ml of absolute ethanol. The rats were sacrificed after 30 min and the gastric mucosa was subjected to macroscopic and histologic assessment and the measurements of adherent mucus, its dimension and chemical composition. In the absence of GGA, ethanol produced advanced macroscopic necrosis (greater than 38%) and the extensive necrotic lesions were visible upon histologic examination. Pretreatment with GGA significantly reduced (p less than 0.001) the extent and depth of mucosal necrotic lesions caused by ethanol, and this protection was not thwarted by indomethacin. Evaluation of the adherent mucus and its dimension by Alcian blue uptake and inverted microscope technique revealed that GGA was also capable of preventing the untoward effect of indomethacin on the adherent gastric mucus gel and its thickness. Results of chemical analyses established that in the absence of GGA indomethacin caused an increase in mucus protein (15%) and a decrease in its covalently bound fatty acids (67%) and lipids (36%). The decrease in lipids was particularly reflected in the content of phospholipids. Indomethacin, however, had no apparent effect on the composition of gastric mucus elaborated in the presence of GGA. The results suggest that gastric mucosal protective action of GGA is not mediated by endogenous prostaglandins but rather appears to involve the metabolism of mucosal lipids.     

Participation of Phosphoinositides in Gastric Mucosal Protection by Colloidal Bismuth Subcitrate against Ethanol-Induced Injury

The mechanism of gastric mucosal protection by an antiulcer agent, colloidal bismuth subcitrate (CBS), against ethanol-induced injury was investigated using in vivo and in vitro systems. The experiments in vivo were conducted with groups of rats with and without indomethacin pretreatment, and the animals received either a dose of CBS (100 mg/kg) or a vehicle (saline), followed 30 min later by ethanol. In the in vitro studies, gastric mucosa segments were cultured in the presence of CBS, ethanol, or both. The results of in vivo experiments revealed that in the absence of CBS, ethanol caused extensive gastric hemorrhagic lesions which were significantly reduced following CBS pretreatment and this effect of CBS was not prevented by indomethacin. The data obtained with gastric mucosal culture established that in comparison to the controls, ethanol caused a 27% decrease in mucin synthesis, while mucin synthesis in the presence of CBS increased by 48%. The increase in mucin synthesis evoked by CBS was accompanied by the enhanced metabolism of mucosal phosphoinositides, as reflected by a decrease in PI (15%) and PIP2 (30%), and an increase in IP1 (26%) and IP3 (67%). In contrast, ethanol, which exhibited detrimental effect on mucin synthesis, caused a decrease in PIP (35%), IP2 (47%) and IP3 (38%), and an increase in PIP2 (80%), and IP1 (51%). However, when the mucosal culture was carried out in the presence of both CBS and ethanol, the detrimental changes evoked by ethanol on mucin synthesis were prevented, and the phosphoinositide and inositide phosphate distribution patterns were quite similar to those in the mucosa cultured in the presence of CBS only.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protective effect of Irsogladine on monochloramineinduced gastric mucosallesions in rats:a comparative study with rebamipide

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吲哚美辛胃损伤中内皮素、一氧化氮、氧自由基的作用及其与胃动力的关系

目的 :研究吲哚美辛胃损伤中内皮素 (ET)、一氧化氮 (NO)、氧自由基的作用 ,以及胃动力对这种损伤的影响。方法 :雄性DS大鼠随机分 4组 :对照组、吲哚美辛 5mg/kg组、吲哚美辛 2 5mg/kg组、阿托品组 (阿托品 1mg/kg +吲哚美辛 2 5mg/kg)。吲哚美辛灌胃 ,灌胃前 10min阿托品皮下注射。取动脉血测ET、NO、丙二醛 (MDA)、超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH Px)水平 ,进行胃形态学观察。结果 :5mg/kg吲哚美辛不引起胃粘膜损伤 ,各检测指标与对照组无差异 ;2 5mg/kg吲哚美辛可引起胃粘膜显著出血性损伤 ,损伤指数为 38 5 7± 12 4 7,病理损伤积分为13 36± 3 37;ET 1和MDA水平升高 (P <0 0 1) ,NO、SOD、GSH Px水平降低 (P <0 0 1,P <0 0 1,P <0 0 5 ) ;阿托品组粘膜损伤较轻 ,损伤指数为 8 71± 3 35 ,病理损伤积分为 3 77± 1 0 4,ET 1含量和对照组无差异 ,MDA水平升高 (P <0 0 5 ) ,NO、SOD含量有所下降 (P <0 0 5 ) ,GSH Px含量无变化。结论 :吲哚美辛所致胃粘膜损伤中 ,ET 1和MDA生成增加起损害作用 ,内源性NO、SOD和GSH Px可清除氧自由基 ,有保护作用 ;阿托品对吲哚美辛所致胃粘膜损伤的保护作用 ,提示胃动力增加在吲哚美辛致溃疡中有重要作用。     

Melatonin protects against gastric ulceration and increases the efficacy of ranitidine and omeprazole in reducing gastric damage

The antiulcer effect of melatonin on gastric lesions caused by restraint-cold stress was studied with the intent of determining the mechanism of action of this agent. Melatonin dose-dependently prevented restraint-cold stress-induced gastric damage with around 90% inhibition at a dose of 60 mg/kg BW. When compared with already marketed antiulcer drugs such as ranitidine and omeprazole, melatonin was found to be more effective than ranitidine but less effective than omeprazole in preventing stress ulcer. As stress-induced gastric lesions are mainly caused by oxidative damage because of hydroxyl radicals (*OH), the effect of melatonin in scavenging the.OH generated during stress conditions in vivo as well as in an in vitro model system were studied. The results indicate that melatonin caused an 88% reduction of endogenous *OH during stress in vivo, an observation confirmed in an established in vitro system. Furthermore, a decrease in the activity of gastric peroxidase (GPO) and an increase in the gastric mitochondrial superoxide dismutase (Mn-SOD) activity because of restraint-cold stress was attenuated by melatonin pretreatment indicating that the indole possibly exerts its gastroprotective effects through its direct as well as indirect antioxidant activities. Moreover, in separate experiments, cotreatment of rats with melatonin and ranitidine or omeprazole was found to protect against stress ulceration in doses at which either of these alone could not protect the stomach. The findings raise the possibility of melatonin being considered as an effective gastroprotective agent individually or as a cotreatment with either ranitidine and omeprazole.     

肝硬化门脉高压性胃病患者胃粘膜炎症与一氧化氮合酶表达

目的 定位、定量研究肝硬化门脉高压性胃症（ＰＨＧ）患者胃粘膜炎症及其与一氧化氮合酶（ｉＮＯＳ／ｃＮＯＳ）表达的关系。方法 肝硬化患者６０例,其中伴有ＰＨＧ者３５例,无胃粘膜病变者２５例。胃粘膜活检３块,Ｂｏｕｉｎ固定,ＨＥ染色及免疫组化ＳＰ法ＭＰＶ显微分光光度计测定ｉＮＯＳ／ｃＮＯＳ表达。结果 肝硬化ＰＨＧ发生率５８．２％,其中７１．４％患者伴有胃粘膜炎症（Ｐ〈０．０５）;胃粘膜炎症者胃粘膜血管ｉ     

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.     

不同抗溃疡药物对应激性溃疡发生、发展过程中细胞凋亡的影响

背景：研究不同抗溃疡药物在防治应激性溃疡(SU)时，其对胃黏膜细胞学行为的作用是否有助于SU的防治。目的：观察抗溃疡药物奥美拉陛、米索前列醇和铝碳酸镁对SU的疗效，及其对细胞凋亡和与凋亡相关的细胞因子一氧化氮合酶(NOS)表达的影响。方法：水浸—束缚应激(WRS)结束后2h，计算胃黏膜损伤的溃疡指数(UI)；原位末端标记(TUNEL)法检测胃黏膜细胞凋亡；免疫组化法检测神经型NOS(nNOS)和诱导型NOS(iNOS)表达的变化。结果：奥美拉陛(0)组、米索前列醇(M)组和铝碳酸镁(H)组胃黏膜损伤均较生理盐水组显著减轻(P＜0．01)，胃黏膜细胞凋亡发生率均显著降低(P＜0．01)，但0组和M组的效果优于H组。与生理盐水组比较，3组用药组的nNOS表达均显著增加(P＜0．01)，iNOS表达均显著降低(P＜0．01)，M组和H组的nNOS表达升高较0组更为显著(P＜0．05)。结论：奥美拉唑、米索前列醇和铝碳酸镁作用于SU发生的不同环节，可显著抑制细胞凋亡的发生，对SU均有明显防治作用。寻找对细胞有直接保护作用的药物以提高细胞的抗应激能力可能是防治SU的最终途径。