Imaging analysis of antiulcer action and the active constituent of Atractylodis rhizoma

Examination of the sizes of gastric mucosal injury has been conducted by visual means. However, the human visual-eye examination may sometimes involve personal biases and errors. In order to reduce these errors, automated analytical apparatuses have been developed. The equipment is generally expensive. In the present study, a low-cost imaging analytical method to examine the antiulcer action of drugs is reported. By using our imaging analytical method, an antiulcer effect of herbal medicine was examined on hydrochloric acid-ethanol induced gastric mucosal injury. Acetone extract of Atractylodis Rhizoma was found to have antiulcer action. In addition, the examination of fractions of the acetone extract, obtained through column chromatography, indicated that atractylon, at 17.5 mg/kg, p.o. significantly inhibits gastric mucosal injury.     

Further evidence of the antiulcer activity of IAC, a novel free radical scavenger

It has been proposed that free radicals, reactive oxygen species (ROS) and reactive nitrogen species play a critical role in gastric mucosal damage. It is well known that the exposure of gastric mucosa to damaging factors such as stress and nonsteroidal anti-inflammatory drugs produces acute ulcers that are mainly mediated by ROS. The aim of the present study was to investigate the gastroprotective properties of bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate (IAC), a novel nonpeptidyl low-molecular-weight radical scavenger, in two different models of gastric ulcer in rats caused by ROS. IAC was orally administered at the doses of 50 and 100 mg/kg before gastric ulceration induced by indomethacin and water immersion and restraint stress. The number and severity of gastric lesions, following macroscopic inspection of the mucosa, were evaluated and expressed as an ulcer score. Oral administration of IAC dosed at 50 and 100 mg/kg was able to significantly prevent gastric ulceration induced by indomethacin and by stress. The gastroprotective effect of IAC on gastric mucosa could be attributed to its intrinsic antioxidant activity, suggesting it as a novel antiulcer agent.     

Changes in cyclic AMP content of rat gastric mucosa induced by ulcerogenic stimuli--in relation to the antiulcer activity of irsogladine maleate.

Changes in the cyclic AMP (cAMP) content of the gastric mucosa induced by ulcerogenic stimuli were investigated in rats. Ligation of the pylorus for 5 hr produced no glandular mucosal lesion, but increased the cAMP content in the fundus and antrum. Aspirin produced glandular mucosal lesions in the pylorus-ligated rats and caused an increase of the cAMP content in the fundus and a decrease in the antrum. Irsogladine maleate (IM), an antiulcer agent, inhibited both the changes in the cAMP content and the mucosal damage induced by aspirin. IM increased the cAMP content in both regions, especially the antrum, in normal rats. Dibutyryl cAMP (dbcAMP) given orally prevented the gastric mucosal lesions induced by aspirin without affecting gastric secretion. These results suggest that 1) the changes in the cAMP content of the fundus and antrum induced by aspirin may be associated with the formation of glandular mucosal damage, 2) the antiulcer activity of IM may be related to an increase of the cAMP content in mucous cells, and 3) dbcAMP given orally may penetrate into the surface mucous cells and activate defensive functions. Thus, cAMP in the mucous cells may protect the gastric mucosa.     

Geranylgeranylacetone protects membranes against nonsteroidal anti-inflammatory drugs

Direct gastric mucosal cell damage mediated by nonsteroidal anti-inflammatory drugs (NSAIDs) is involved in the formation of NSAID-induced gastric lesions. We recently suggested that this direct cytotoxicity of NSAIDs is caused by their membrane-permeabilization activity. Geranylgeranylacetone (GGA), a clinically used antiulcer drug, can protect gastric mucosa against lesion formation mediated by NSAIDs. However, the mechanism by which this occurs is not fully understood. In this study, we show that GGA acts to stabilize membranes against NSAIDs. GGA suppressed NSAID-induced permeabilization of calcein-loaded liposomes and NSAID-induced stimulation of K(+)-efflux across the cytoplasmic membrane in cells. GGA was effective even when coadministered with NSAIDs and was also able to restore membrane fluidity that had been compromised by NSAIDs. This mechanism seems to play an important role in the antiulcer activity of GGA.     

Effects of antisecretory drugs on mucosal erosions induced by intragastric distension in rats: a comparative study

The antiulcer effects of two classical antisecretory agents, cimetidine and pirenzepine, were compared with those of prostaglandin E2 and carbenoxolone sodium. The acid inhibitory action of drugs was not important in our study since the ulcer model employed consisted of perfusing the stomach continuously, at a high intraluminal pressure (120 mm H2O), with a simulated gastric juice (0.1 M HCl plus 600 mg pepsin/l). Cimetidine and pirenzepine failed to inhibit gastric erosions, whereas prostaglandin E2 and carbenoxolone greatly reduced the severity of the mucosal lesions. Long-term treatment with cimetidine did not prevent gastric damage. These findings indicate that pure antisecretory agents do not directly increase the capacity of the mucosa to resist damage.     

Dual effects of zinc sulphate on ethanol-induced gastric injury in rats: possibly mediated by an action on mucosal blood flow

The present study examines the protective effect of zinc sulphate against ethanol-induced gastric mucosal ulcers in rats. Absolute ethanol decreased the gastric mucosal blood flow and produced haemorrhagic lesions in the glandular mucosa. Zinc sulphate preincubation in an ex-vivo stomach chamber preparation prevented the formation of ethanol-induced lesions and attenuated the decrease of blood flow produced by ethanol. Subcutaneous injection of the same doses of the drug at 15 and 30 min before ethanol exposure, markedly reduced the blood flow and also aggravated ethanol-induced gastric injury; however, when injected at 23 and 24 h before ethanol administration, zinc sulphate protected against lesion formation but had no effect on the vascular changes induced by ethanol in the gastric glandular mucosa. These findings show that the antiulcer effect of zinc sulphate occurs only when the drug is given orally, or injected s.c. 23 and 24 h before ethanol challenge. Furthermore, this protective action is probably not entirely mediated by preservation of the gastric mucosal blood flow.     

A novel gastric lesion model induced in rats by partial gastric vascular ligation

Previous studies have suggested that histamine treatment after gastric vascular ligation induces mucosal damage in the rat stomach. Although ligation of left gastric artery and vein (L-AV) alone did not cause any damage in the stomach within 4 h, but provoked mild lesions due to ischemia 24 h later. In the present study we demonstrated a new model of gastric lesions induced by L-AV ligation and examined the effects of various anti-ulcer drugs on this lesion model. The gastric lesions induced by L-AV ligation occurred at the corpus and antrum, especially at the corpus-antrum border, when examined 24 h later, and the severity of damage reached maximum 3 days after L-AV ligation. Repeated treatment with omeprazole or sucralfate for 3 days significantly prevented the development of gastric lesions induced by L-AV ligation, in whole mucosa, including the antrum. By contrast, famotidine given for 3 days showed a significant protection against total lesions in the whole mucosa, but had no effect on the antral lesions. Both omeprazole and famotidine dose-dependently decreased gastric acid output while sucralfate raised the intraluminal pH due to the acid-neutralizing action. These results suggest that the pathogenesis of gastric lesions induced by L-AV ligation differs depending on the region, the corpus and the antrum, and the lesions occurred in the latter area seem to be resistant to acid suppression. It is assumed that this new model of gastric lesions is useful for screening the drugs that affect gastric mucosal defense rather than acid secretion.     

Mechanisms of gastroprotection by lansoprazole pretreatment against experimentally induced injury in rats: role of mucosal oxidative damage and sulfhydryl compounds

This study investigated the mechanisms involved in the protective actions exerted by lansoprazole against experimental gastric injury. Following the intraluminal injection of ethanol-HCl, the histomorphometric analysis of rat gastric sections demonstrated a pattern of mucosal lesions associated with a significant increase in the mucosal contents of malondialdehyde and 8-iso-prostaglandin F(2alpha) (indices of lipid peroxidation), as well as a decrease in the levels of mucosal sulfhydryl compounds, assayed as reduced glutathione (GSH). Pretreatment with lansoprazole 90 micromol/kg, given intraduodenally as single dose or once daily by intragastric route for 8 days, significantly prevented ethanol-HCl-induced gastric damage. The concomitant changes in the mucosal levels of malondialdehyde, 8-iso-prostaglandin F(2alpha) and GSH elicited by ethanol-HCl were also counteracted by lansoprazole. In separate experiments, performed on animals undergoing 2-h pylorus ligation, lansoprazole did not enhance the concentration of prostaglandin E(2), bicyclo-prostaglandin E(2), or nitric oxide (NO) metabolites into gastric juice. Western blot analysis revealed the expression of both type 1 and 2 cyclooxygenase (COX) isoforms in the gastric mucosa of pylorus-ligated rats. These expression patterns were not significantly modified by single-dose or repeated treatment with lansoprazole. Lansoprazole also exhibited direct antioxidant properties by reducing 8-iso-prostaglandin F(2alpha) generation in an in vitro system where human native low-density lipoproteins were subjected to oxidation upon exposure to CuSO(4). The present results suggest that the protective effects of lansoprazole can be ascribed to a reduction of gastric oxidative injury, resulting in an increased bioavailability of mucosal sulfhydryl compounds. It is also proposed that lansoprazole does not exert modulator effects on the gastric expression of COX isoforms as well as on the activity of NO pathways.     

Inhibition of Helicobacter pylori-induced cyclo-oxygenase-2 aggravates NSAID-caused gastric damage in Mongolian gerbils

BACKGROUND: The effect of Helicobacter pylori infection on non-steroidal anti-inflammatory drug-induced gastric mucosal injury is controversial. AIM: To examine the effect of the interaction between H. pylori and non-steroidal anti-inflammatory drugs on gastric mucosal injury. METHODS: Mongolian gerbils infected with H. pylori were treated with indometacin at 8 mg/kg for 2 days or 7 days. Mucosal damage was assessed by macroscopic and histological examination, and myeloperoxidase activity was measured as an index of neutrophil infiltration. The expression levels of cyclo-oxygenase proteins were determined by Western blot analysis and cyclo-oxygenase activity. RESULTS: A 2-day course of indometacin did not cause an increase in gastric damage in H. pylori-infected Mongolian gerbils compared to uninfected gerbils, while a 7-day course of indometacin caused additive gastric damage in H. pylori-infected animals. H. pylori infection induced cyclo-oxygenase-2 expression in the stomach. Treatment with indometacin for 2 days did not significantly affect cyclo-oxygenase activity in H. pylori-infected animals, while treatment for 7 days inhibited both cyclo-oxygenase-1 and cyclo-oxygenase-2 activities. Pre-treatment with a selective cyclo-oxygenase-2 inhibitor aggravated mucosal injury in H. pylori-infected animals treated or not treated with indometacin for 2 days. CONCLUSIONS: Our results suggest that cyclo-oxygenase-2 protein induced by H. pylori infection may be involved in the defence of the gastric mucosa against damage caused by non-steroidal anti-inflammatory drugs. Therefore, inhibition of cyclo-oxygenase-2 activity may enhance non-steroidal anti-inflammatory drug-caused gastric damage in H. pylori-infected animals.     

微米大黄炭对乙醇诱导大鼠急性胃黏膜损伤的保护作用及炎症因子的影响

目的：探讨微米大黄炭对乙醇所致急性胃黏膜损伤的保护作用及机制。方法：采用无水乙醇灌胃诱导大鼠急性胃黏膜损伤模型,测定各组大鼠胃黏膜一般状况、损伤指数,以及血清TNF-α、IL-6、IL-4水平。结果：模型组大鼠的胃黏膜损伤指数、IL-6、TNF-α水平均显著高于正常组（P<0.01）,IL-4水平显著低于正常组（P<0.05）。微米大黄炭组及奥美拉唑镁肠溶片组胃黏膜损伤指数低于模型组（P<0.05）,且微米大黄炭降低更明显（P<0.01）。微米大黄炭组较模型组的TNF-α、IL-6水平显著降低,IL-4水平显著升高,但较奥美拉唑镁肠溶片组比较无统计学差异（P>0.05）。结论：微米大黄炭对乙醇诱导的急性胃黏膜损伤具有一定的保护作用,其作用机制可能与抑制TNF-α、IL-6的释放,增加IL-4水平有关。     

Antisecretory and anti-ulcer effects of morphine in rats after gastric mucosal aggression

The effects of morphine on gastric secretion, barrier mucus and mucosal lesions were studied in pylorus-ligated rats treated with the ulcerogenic agents, indomethacin, aspirin or taurocholic acid. All three ulcerogenic agents induced significant mucosal lesions. Morphine decreased gastric acid secretion and suppressed the aspirin- and taurocholic acid-induced, but not the indomethacin-induced mucosal lesions. These results suggest that the ulcerogenic mechanisms of indomethacin and the other agents are not identical. Moreover the antiulcer effect of morphine appears to be mediated by an increased barrier mucus level: the amount of Alcian blue bound to the mucosa, an indirect estimate of the adherent mucus layer, was increased by morphine and correlated with its protective effect. All morphine effects were reversed by naloxone.     

Effects of the anti-ulcer agents ecabet sodium,cimetidine and sucralfate on acetylsalicylic acid-induced gastric mucosal damage deteriorated by renal failure in rats

Renal failure including post-renal transplantation increases the susceptibility of the upper gastrointestinal mucosa to injury. The aim of this study was to confirm the influence of renal failure on gastric mucosal barrier and the protective effect of various anti-ulcer agents in rats. Renal failure (RF) was induced by 45-min left renal artery clamping and right-uninephrectomy. Four days after surgery, gastric mucosal lesions were induced by intragastric administration of acetylsalicylic acid (ASA, CAS 50-78-2) (100 mg/kg). Anti-ulcer agents were given orally 30 min before ASA administration. RF induced moderate gastric mucosal damages, but significantly worsened the ASA-induced gastric lesions. Ecabet sodium (CAS 86408-72-2) and cimetidine (CAS 51481-61-9) significantly inhibited ASA-induced gastric lesions in RF rats, whereas sucralfate (CAS 54182-58-0) tended to inhibit it. ASA and all of these anti-ulcer agents had no effect on the serum creatinine and blood urea nitrogen levels increased by RF. The gastric mucosa of RF rats is more susceptible to damage induced by ASA. Ecabet and cimetidine potently inhibited gastric lesions in RF rats suggesting its utility for the gastric mucosal damage in patients with RF including post-renal transplant.     

表皮生长因子对萎缩性胃炎大鼠胃黏膜上皮增生的影响

目的：探讨表皮生长因子（epidermal growth factor,EGF）对大鼠萎缩性胃炎（chronic atrophic gastritis,CAG）动物模型的治疗作用。方法：大鼠CAG模型建立后,分别给予EGF、硫糖铝及生理盐水处理,12周后取出全胃,观察各组大鼠胃黏膜病理变化、测定腺体增殖细胞核抗原（proliferating cell nuclear antigen,PCNA）表达、测量胃黏膜腺体厚度（L1）和黏膜肌层（L2）之比及胃窦固有腺体总个数。结果：EGF组、硫糖铝组大鼠胃黏膜腺体排列规则,未发现有恶性增殖现象。EGF组胃窦L1／L2值为8．6±1．2,较硫糖铝组、模型组（6．6±1．6,5．0±0．9）明显增加（P〈0．05,P〈0．01）。EGF组、硫糖铝组的胃窦腺体个数值分别为（52．0±5．8）和（34．8±4．3）,较模型组（27．1±2．2）明显增加（P〈0．01）;EGF组、硫糖铝组PCNA表达阳性的高度分别为（84．5±2．9）um和（76．8±1．7）um,较模型组[（63．3±9．2）um]明显增加（P〈0．01,P〈0．05）,但EGF组的效果要优于硫糖铝组（P〈0．01）。结论：EGF对于大鼠CAG动物模型具有恢复治疗作用,且在促进胃腺体增殖作用方面的效果优于硫糖铝。     

Gastrointestinal mucosal injury following repeated daily oral administration of conventional formulations of indometacin and other non-steroidal anti-inflammatory drugs to pigs: a model for human gastrointestinal disease

Non-steroidal anti-inflammatory drugs (NSAIDs) vary in their propensity to cause damage in different regions of the gastrointestinal (GI) tract in laboratory animals and humans. This may depend on the type of drug formulation as well as the intrinsic pharmacological properties of the drugs. The purpose of this study was to determine the effects of NSAIDs, with cyclooxygenase 1 and 2 inhibitory activity but with different potency as inhibitors of prostaglandin production, when given orally as tablet/capsule formulations of NSAIDs for 10 days to pigs, a species that has close resemblance in structure and function of the tract to that in humans. Three capsule or tablet formulations of NSAIDs were given orally to pigs for 10 days. GI bleeding was measured by determination of radioactive iron in the faeces from (59)Fe-pre-labelled red blood cells. The blood loss was compared with the pathological changes in the GI mucosa observed at autopsy, mucosal myeloperoxidase (MPO) activity as an index of leucocyte infiltration, and plasma and mucosal concentrations of the drugs at termination assayed by high-performance liquid chromatography. Mucosal damage and bleeding varied according to the type of NSAID. Gastroduodenal ulcers and lesions occurred with the cyclooxygenase inhibitors indometacin (indomethacin) (Indocid capsules 10 or 5 mg kg(-1) day(-1) b.i.d.), aspirin (USP tablets 150 mg kg(-1) day(-1) b.i.d) and naproxen (Apotex tablets 50 or 75 mg kg(-1) day(-1) b.i.d.), and there was an increase in the cumulative (i.e. 10-day) blood loss at higher doses of indometacin and naproxen, and with aspirin. There was no statistically significant increase in gastric or intestinal mucosal MPO activity in the non-damaged mucosa with these drugs and this was confirmed by histological observations in non-lesioned areas of the mucosa. Indometacin produced focal ulcers in the caecum but this was not observed with the other drugs. All the NSAIDs produced significant blood loss coincident with gastric ulceration but no increase in gastric or intestinal MPO activity. Plasma concentrations of the non-aspirin NSAIDs were within the range encountered therapeutically in humans. The mucosal concentrations of indometacin in the gastric and intestinal mucosa correlated with mucosal injury. These findings show that: (i) NSAIDs vary in their propensity to produce mucosal injury in different regions of the GI tract according to their pharmacological properties and formulation; (ii) mucosal injury from some NSAIDs may not directly relate to blood loss at low doses of NSAIDs and this may depend on inhibition of platelet aggregation; and (iii) the occurrence of caecal ulcers uniquely observed with indometacin treatment may be relevant to the development of intestinal pathology (e.g. diaphragm-like structures) seen occasionally in humans. These results suggest that the pig model employed in the present studies may be useful for investigations of GI damage from NSAID tablets/capsules, especially in regions that are generally inaccessible to routine endoscopic investigations in humans (e.g. the proximal regions of the large intestine).     

Mast cells do not contribute to nonsteroidal anti-inflammatory drug-induced gastric mucosal injury in rodents

Background: By releasing pro-ulcerogenic mediators, mast cells may contribute to the mucosal injury associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs).
Methods: To study this, rat and mouse models of NSAID-induced gastric damage were used in which administration of indomethacin causes haemorrhagic injury in the corpus region of the stomach, and the "re-feeding" model in which penetrating antral ulcers are induced in the rat by naproxen. Mast cell degranulation was determined histologically and by measurement of tissue and serum levels of rat mast cell protease-II, a mediator specific to mucosal mast cells. The effects of either increasing or decreasing the number of gastric mucosal mast cells on the susceptibility of the stomach to injury induced by indomethacin were also studied.
Results: Gastric injury induced by indomethacin was not accompanied by significant mast cell degranulation. Moreover, neither increasing nor decreasing the number of gastric mucosal mast cells had a significant effect on the susceptibility of the gastric mucosa to damage induced by indomethacin. In the re-feeding model, prior depletion of gastric mucosal mast cells did not significantly affect the severity of antral ulceration induced by naproxen, nor the ability of prostaglandin E₂ to prevent this damage. Finally, indomethacin-induced damage was similar in severity in mice with a genetic defect resulting in the complete absence of mast cells as it was in normal, congenic littermates.
Conclusion: Mast cells do not play a significant role in the development of gastric injury induced by acute NSAID administration in the rat or mouse.     

Effects of anti-ulcer agents on ethanol-induced gastric mucosal lesions in D-galactosamine-induced hepatitis rats

Patients with hepatic injury have an increased incidence of gastric ulcers and erosions. In this study, the effect of D-galactosamine(GalN)-induced hepatitis on ethanol-induced gastric mucosal lesions and the protective effect of anti-ulcer agents in rats were examined. Subcutaneous injection of GalN (1 g/kg) remarkably increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities suggesting induction of hepatic injury. Gastric mucosal lesions induced by ethanol were significantly aggravated in GalN-induced hepatitis rats. Orally administered ecabet (CAS 86408-72-2; 20-200 mg/kg) dose dependently inhibited ethanol-induced gastric mucosal lesions in GalN-induced hepatitis rats. Sucralfate (CAS 54182-58-0) tended to inhibit the gastric mucosal lesions at a dose of 200 mg/kg but teprenone (CAS 6809-52-5), cimetidine (CAS 51481-61-9) and rebamipide (CAS 90098-04-7) had little effect. All anti-ulcer agents had no effect on the serum ALT and AST activities increased by GalN pretreatment. These results indicate that the gastric mucosa of GalN-induced hepatitis rats is more susceptible to injury induced by luminal irritants such as ethanol. Ecabet potently inhibited gastric mucosal lesions suggesting its clinical utility for the gastric mucosal damage in patients with hepatic injury.     

Decrease in aspirin-induced gastric mucosal damage in rats by oral administration of the cytotoxic drugs melphalan and methotrexate

Gastric mucosal damage by aspirin and chemotherapeutic drugs was studied in Wistar rats. Aspirin 60 mg given by stomach tube caused substantial gastric mucosal damage as judged by visual examination of the stomachs removed four hours later. Melphalan and methotrexate given daily for four days had no significant macroscopic effect on the gastric mucosa, but reduced the damage caused by aspirin. This protective effect may involve a stimulation of prostaglandin synthesis by the stomach, increased mucus secretion, and/or inhibition of acid secretion.     

Effects of taurocholic acid/HCl alone or after pretreatment with geranylgeranylacetone on phospholipid metabolism in rat gastric mucosa

Changes in phospholipid metabolism in gastric mucosa caused by instillation of taurocholic acid (TCA)/HCl (80 mM/300 mM) into the stomach of rats and the effects of pretreatment with an antiulcer agent, geranylgeranylacetone (GGA), were studied after intravenous injection of radioisotope-labeled precursors. The instillation of TCA/HCl rapidly reduced the incorporation of labeled fatty acids and glycerol into phosphatidylcholine and phosphatidylethanolamine, indicating the inhibition of de novo synthesis of phospholipids. These changes were restored by 120-150 min after the TCA/HCl treatment. Pretreatment with GGA enhanced the incorporation of precursors into phosphatidylcholine immediately after the instillation of TCA/HCl. Experiments in which the mucosal lipids were labeled with fatty acids prior to the instillation of TCA/HCl showed that the degradation of cellular lipids and release of the products into the gastric lumen were induced by TCA/HCl and that these changes were not prevented by GGA. Since GGA almost completely inhibited the gastric lesions induced by TCA/HCl, the enhancement of synthesis of mucosal phosphatidylcholine induced by GGA may be involved in the prevention of gastric damage. The incorporation of labeled fatty acids into free fatty acid fraction and diacylglycerol was increased quickly by the TCA/HCl treatment, suggesting early damage to the blood vessels of the gastric mucosa; these changes were inhibited significantly by GGA.     

Decrease in aspirin-induced gastric mucosal damage in rats by oral administration of the cytotoxic drugs melphalan and methotrexate

Gastric mucosal damage by aspirin and chemotherapeutic drugs was studied in Wistar rats. Aspirin 60 mg given by stomach tube caused substantial gastric mucosal damage as judged by visual examination of the stomachs removed four hours later. Melphalan and methotrexate given daily for four days had no significant macroscopic effect on the gastric mucosa, but reduced the damage caused by aspirin. This protective effect my involve a stimulation of prostaglandin synthesis by the stomach, increased mucus secretion, and/or inhibition of acid secretion.