Ethanol induced duodenal lesions in man. Protective effect of prostaglandin

Protective effects of a triple-fermented barley extract (FBe) against HCl/EtOH-induced gastric mucosa damage in mice

This study was designed to observe the possible protective effects of a triple-fermented barley (Hordeum vulgare L.) extract (FBe) obtained by saccharification and using Saccharomyces cerevisiae and Weissella cibaria in alleviating gastric damage induced by a hydrochloric acid (HCl) and ethanol (EtOH) mixture in mice. After oral administration of FBe (300, 200, and 100 mg/kg) followed by 1 hr before and after the single treatment of HCl/EtOH (H/E) mixture, the hemorrhagic lesion scores, histopathology of the stomach, gastric nitrate/nitrite content, lipid peroxidation, and antioxidant defense systems including catalase and superoxide dismutase activities were observed. Following a single oral treatment of H/E-induced gastric damages as measured by hemorrhagic gross lesions and histopathological gastric, ulcerative lesions were significantly and dose-dependently (p < 0.01 or p < 0.05) inhibited in mice, when all three different doses of FBe were administered as compared to those in H/E control mice. In particular, FBe also increased gastric nitrate/nitrite content and strengthened the antioxidant defense, with a decrease in the level of gastric lipid peroxidation, but increased the activities of CAT and SOD. Moreover, the effects of FBe are comparable to that of ranitidine, a reference drug. The obtained results suggest that this fermented barley extract prevented mice from H/E-induced gastric mucosal damages through the suppression of inflammatory responses and oxidative stress-responsive free radicals. Thus, FBe can be useful to treat patients suffering from gastric mucosal disorders as a potent food supplement, and thereby, it would increase the necessity of application in the food industry.

Long-term oral melatonin administration reduces ethanol-induced increases in duodenal mucosal permeability and motility in rats

AIM

Increased intestinal epithelial permeability is associated with intestinal inflammation and dysfunction. The aim of the present study was to investigate the role of long-term oral melatonin administration on ethanol-induced increases in duodenal mucosal permeability and hypermotility.

METHODS

Male Sprague-Dawley rats were administered melatonin in their tap water (0.1 mg mL(-1) or 0.5 mg mL(-1) ) for 2 or 4 weeks. After the treatment period, the rats were anaesthetized with Inactin(®) , and a 30-mm duodenal segment was perfused in situ. The effects on duodenal mucosal paracellular permeability, bicarbonate secretion, fluid flux and motor activity were studied. The expression levels of the tight junction components, zona occludens (ZO)-1, ZO-2, and ZO-3, claudin-2, claudin-3, claudin-4, occludin, and myosin light chain kinase and of the melatonin receptors MT1 and MT2 were assessed using qRT-PCR.

RESULTS

Melatonin administration for 2 weeks significantly reduced the basal paracellular permeability, an effect that was absent after 4 weeks. Perfusing the duodenal segment with 15% ethanol induced marked increases in duodenal paracellular permeability, bicarbonate secretion and motor activity. Melatonin for 2 weeks dose-dependently reduced ethanol-induced increases in permeability and motor activity. Four weeks of melatonin administration reduced the ethanol-induced increases in duodenal motility and bicarbonate secretion but had no effect on the increases in permeability. Two weeks of melatonin administration upregulated the expression of MT1 and MT2 , although both were downregulated after 4 weeks. Melatonin downregulated the expression of ZO-3 and upregulated the expression of claudin-2, even as all other mRNA-levels investigated were unaffected.

CONCLUSION

Although further studies are needed, our data demonstrate that melatonin administration markedly improves duodenal barrier functions, suggesting its utility in clinical applications when intestinal barrier functions are compromised.

Gastroprotective effect of selenium on ethanol-induced gastric damage in rats

In the present study, we examined the gastroprotective effect of selenium against ethanol-induced gastric mucosal lesions in rats. The gastric mucosal lesions were produced by oral administration with various concentrations of ethanol for three days, and 80% ethanol treatment was determined to be the optimal condition for induction of gastric damage. To identify the protective effect of selenium on ethanol-induced gastric damage, various doses of selenium were given as pretreatment for three days, and then gastric damage was induced by 80% ethanol treatment. Selenium showed a protective effect against ethanol-induced gastric mucosal lesions in a dose dependent manner. Specifically, 100 μg/kg selenium showed the highest level of gastroprotection. In addition, selenium markedly attenuated ethanol-induced lipid peroxidation in gastric mucosa and increased activities of radical scavenging enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase in a dose-dependent manner. Histological data showed that 100 μg/kg selenium distinctly reduced the depth and severity of the ethanol induced gastric lesion. These results clearly demonstrate that selenium inhibits the formation of ethanol-induced gastric mucosal lesions through prevention of lipid peroxidation and activation of enzymatic radical scavenging.

Protective effects of a gastrointestinal agent containing Korean red ginseng on gastric ulcer models in mice

Background

Korean red ginseng (KRG) is a ginseng that has been cultivated and aged for 4-6 years or more, and goes through an extensive cleaning, steaming and drying process. KRG contains more than 30 kinds of saponin components and has been reported as having various biological properties, such as anti-fatigue action, immune restoration, and neurovegetative effect. The purpose of this study was to assess the effects of a KRG-containing drug (KRGCD) on gastric ulcer models in mice.

Methods

Stomach ulcers were induced by oral ingestion of hydrochloride (HCl)/ethanol or indomethacin. Treatment with KRGCD (30, 100, and 300 mg/kg, p.o.) occurred 1 hr before the ulcer induction. Effect of KRGCD on anti-oxidant activity and gastric mucosal blood flow with a laser Doppler flowmeter in mice stomach tissue was evaluated.

Results

KRGCD (100 and 300 mg/kg, p.o.) significantly decreased ethanol- and indomethacin-induced gastric ulcer compared with the vehicle-treated (control) group. KRGCD (100 and 300 mg/kg) also decreased the level of thiobarbituric acid reactive substance (TBARS) and increased gastric mucosal blood flow compared with the control group.

Conclusions

These results suggest that the gastroprotective effects of KRGCD on mice ulcer models can be attributed to its ameliorating effect on oxidative damage and improving effect of gastric mucosal blood flow.

Gastric mucosal defense and cytoprotection: bench to bedside

The gastric mucosa maintains structural integrity and function despite continuous exposure to noxious factors, including 0.1 mol/L HCl and pepsin, that are capable of digesting tissue. Under normal conditions, mucosal integrity is maintained by defense mechanisms, which include preepithelial factors (mucus-bicarbonate-phospholipid "barrier"), an epithelial "barrier" (surface epithelial cells connected by tight junctions and generating bicarbonate, mucus, phospholipids, trefoil peptides, prostaglandins (PGs), and heat shock proteins), continuous cell renewal accomplished by proliferation of progenitor cells (regulated by growth factors, PGE(2) and survivin), continuous blood flow through mucosal microvessels, an endothelial "barrier," sensory innervation, and generation of PGs and nitric oxide. Mucosal injury may occur when noxious factors "overwhelm" an intact mucosal defense or when the mucosal defense is impaired. We review basic components of gastric mucosal defense and discuss conditions in which mucosal injury is directly related to impairment in mucosal defense, focusing on disorders with important clinical sequelae: nonsteroidal anti-inflammatory drug (NSAID)-associated injury, which is primarily related to inhibition of cyclooxygenase (COX)-mediated PG synthesis, and stress-related mucosal disease (SRMD), which occurs with local ischemia. The annual incidence of NSAID-associated upper gastrointestinal (GI) complications such as bleeding is approximately 1%-1.5%; and reductions in these complications have been demonstrated with misoprostol, proton pump inhibitors (PPIs) (only documented in high-risk patients), and COX-2 selective inhibitors. Clinically significant bleeding from SRMD is relatively uncommon with modern intensive care. Pharmacologic therapy with antisecretory drugs may be used in high-risk patients (eg, mechanical ventilation >or=48 hours), although the absolute risk reduction is small, and a decrease in mortality is not documented.

Role of vascular endothelial growth factor in portal hypertensive gastropathy

BACKGROUND AND AIMS

Portal hypertensive gastropathy (PHG) is now recognized as a distinct entity; however, the angiogenesis in the portal hypertensive gastric mucosa has yet to be elucidated. Vascular endothelial growth factor (VEGF) is a potent angiogenic factor involved in both physiological and pathological angiogenesis. The aim of this study was thus to examine the function of VEGF in the portal hypertensive and non-portal hypertensive gastric mucosa.

METHOD

Forty-five cirrhotic patients were divided into 3 groups as follows. Group I included 15 patients without PHG who were treated with 1.5 g teprenone/day for 8 weeks: PHG(-)-t. Group II included 15 patients with PHG who were not treated with teprenone: PHG(+)-n. Group III included 15 patients with PHG who were treated with teprenone for 8 weeks: PGH(+)-t. The gastric mucosal blood flow (GMBF), the concentration of gastric mucosal VEGF and hexosamine and the endoscopic findings were studied both before and after medication.

RESULTS

Before teprenone treatment, the GMBF in the antrum, fundus, fornix were significantly higher in PHG(+)-n than PHG(-)-t. After treatment, the GMBF in the fundus and fornix significantly decreased more than before treatment in the PHG(+)-t. After treatment, the GMBF in the antrum increased significantly more than before treatment in PHG(-)-t. The gastric VEGF and hexoxamine concentration in the antrum were significantly higher in PHG(+)-n than in PHG(-)-t. After treatment, the gastric VEGF and hexosamine concentration in the antrum significantly decreased in PHG(+)-t while no change in concentration was recognized in PHG(+)-n. In the endoscopic findings, a decrease in the PHG score was recognized in 2 patients in PHG(+)-t.

CONCLUSION

Portal hypertensive gastric mucosal change was thus found to trigger a high concentration of VEGF and hexosamine. Such increased activity of VEGF and hexosamine may thus account for the presence of active congestion in PHG.

Suppressive effect of melatonin administration on ethanol-induced gastroduodenal injury in rats in vivo

1. Melatonin protection against ethanol-induced gastroduodenal injury was investigated in duodenumligated rats. 2. Melatonin, injected i.p. 30 min before administration of 1 ml of absolute ethanol, given by gavage, significantly decreased ethanol-induced macroscopic, histological and biochemical changes in the gastroduodenal mucosa. 3. Ethanol-induced lesions were detectable as haemorrhagic streaks. Ethanol administration damaged 36% and 25% of the total gastric and duodenal surface, respectively. Melatonin treatment reduced ethanol-induced gastric and duodenal damage to 14% and 8%, respectively. When indomethacin was given together with ethanol, the gastric damaged area was 44% of the total surface, while the duodenal damaged area was 35%; melatonin administration reduced the damage to only 13% of the total gastric surface and to 12% of total duodenal surface. 4. Both stomach and duodenum of ethanol-treated animals showed polymorphonuclear leukocyte (PMN) infiltration. The number of PMN increased more than 600 and 200 times in stomach and duodenum, respectively, following ethanol administration. Melatonin treatment reduced ethanol-induced PMN infiltration by 38% in the stomach and 20% in the duodenum. In indomethacin-ethanol-treated rats, the number of PMN increased by 875% compared to control group in the stomach and by 264% in duodenum. Melatonin administration reduced the indomethacin-ethanol-induced PMN rise by 57% in the stomach and 40% in the duodenum. 5. Gastroduodenal total glutathione (tGSH) concentration and glutathione reductase (GSSG-Rd) activity were significantly reduced following ethanol and indomethacin-ethanol administration. Melatonin ameliorated both the decrease in tGSH concentration as well as the reduction of GSSG-Rd activity elicited by ethanol both in the stomach and duodenum; melatonin was effective against indomethacin-ethanol-induced damage only in the stomach. 6. Ethanol-induced gastroduodenal damage is believed to be mediated by the generation of free radicals. Recently, a number of in vivo and in vitro experiments have shown melatonin to be an effective antioxidant and free radical scavenger; thus, we conclude that the protection by melatonin against ethanol-induced gastroduodenal injury is due, at least in part, to its radical scavenging activity.

Fatty acid-mediated gastroprotection does not correlate with prostaglandin elevation in rats exposed to various chemical insults

This study involved a comparison of activity of several long-chain fatty acids (arachidonic acid, dihomo-[gamma]-linolenic acid, linoleic acid, and oleic acid) for protection against gastric mucosal damage elicited by taurocholic acid, acidified aspirin, and ethanol in rats. Each damaging agent induced gastric mucosal lesions in the corpus. Mucosal damage was induced by all agents, and all fatty acids protected the gastric mucosa; however, ethanol and arachidonic acid were the most potent damaging and protecting agents, respectively. Maximally protective doses for prevention of taurocholic acid-induced damage by arachidonic, dihomo-[gamma]-linolenic, linoleic, and oleic acids were 50, 200, 100, and 200 mg/kg, respectively; however, 10 mg/kg arachidonic acid reduced lesion length by > 50%, whereas minimally effective doses of the other fatty acids were > or = 50 mg/kg. Similar potency differences were observed for fatty acid protection against acidified aspirin-induced gastric damage. Although all the fatty acids reduced macroscopic damage, histologic studies showed they did not totally eliminate surface mucosal damage. Microscopic analysis showed that treatment with dihomo-[gamma]-linolenic acid or oleic acid attenuated depletion of neutral and acidic glycoproteins from the mucus neck cells of the gastric mucosa in response to exposure to taurocholic acid. Despite having similar gastroprotective activity, arachidonic, dihomo-[gamma]-linolenic, linoleic, and oleic acids had very dissimilar abilities to elevate gastric mucosal E-series prostaglandins. Both arachidonic and dihomo-[gamma]-linolenic acids elevated E-series prostaglandins, but arachidonic acid had 2-5-fold greater gastroprotective potency. Furthermore, oleic and linoleic acids, which had protective potency similar to that dihomo-[gamma]-linolenic acid, did not significantly elevate prostaglandins. These studies failed to demonstrate an absolute correlation between prostaglandin elevation and gastroprotection. The results of this investigation suggest that prostaglandin elevation, although associated with gastroprotection, does not appear to be the sole mechanism for fatty acid-mediated protection of rat gastric mucosa.

Fish oil reduces ethanol-induced damage of the duodenal mucosa in humans

Eight healthy volunteers were studied before and after 3 weeks of dietary supplementation with fish oil (10.5 g day-1, 18% (1.9 g) eicosapentaenoic acid). Duodenal mucosal lesions were induced by instillation of 40 ml ethanol (40%). Mean endoscopic lesion score was lower after fish oil treatment (1.62 +/- 0.32; mean +/- SEM) than before (3.25 +/- 0.31; P less than 0.01). Histologic lesion score fell from 22.75 +/- 1.98 before treatment to 13.50 +/- 1.51 after fish oil (P less than 0.01). Basal and pentagastrin-stimulated gastric acid output remained unaffected. Release of prostaglandin E2, 6-keto-prostaglandin F1 alpha, and thromboxane B2 from biopsy specimens of the duodenal mucosa in vitro was not significantly altered after fish oil ingestion. In the same in vitro system calcium ionophore A23187-induced release of total leukotriene C (LTC) increased from 10.6 +/- 1.5 ng g-1 mucosa 20 min before treatment to 30.4 +/- 3.2 ng after fish oil. High pressure liquid chromatography analysis showed that this increase was partly due to formation of LTC5 as after fish oil 28% of total LTC were identified as LTC5 whereas 72% were LTC4. We conclude that in humans fish oil reduces ethanol-induced damage of the duodenal mucosa without inhibiting gastric acid secretion or stimulating prostaglandin formation. It remains to be clarified if the changes in leukotriene formation are relevant for the mucosaprotective fish oil effect.

The inhibitory effect of anti-tumor drugs on phosphatidylcholine synthesis and its reversal by geranylgeranylacetone in the isolated guinea pig gastric glands

To clarify the mechanism by which the administration of anti-tumor drugs, antibiotics or hypoglycemic agents causes gastric mucosal injury, the effects of these drugs on phosphatidylcholine synthesis in isolated guinea pig gastric glands were examined in vitro. Anti-tumor drugs such as tegafur, cyclophosphamide, and mitomycin C decreased [3H]choline incorporation into phosphatidylcholine. Furthermore, tegafur at 0.4 mg/ml decreased [3H]choline incorporation in the glands that had been pulsed with [3H]choline incorporation, suggesting that tegafur exerts its effect by inhibiting late step of phosphatidylcholine synthesis in the stomach. On the other hand, cefaclor and glibenclamide had no effect on [3H]choline incorporation. Geranylgeranylacetone, an anti-ulcer drug partially restored tegafur-induced reduction of [3H]choline incorporation into phosphatidylcholine. These results suggest that the anti-tumor drug-induced gastric mucosal injury may be due to drug-induced decrease in phosphatidylcholine synthesis, which the restoration of phosphatidylcholine synthesis by geranylgeranylacetone may explain its anti-ulcer action on drug-induced gastric mucosal lesions in vivo.

Human antral damage induced by alcohol is potentiated by enprostil

Enprostil, a synthetic analogue of prostaglandin E2, has been shown to protect the human gastroduodenal mucosa from aspirin injury. This study was designed to determine if enprostil protected against alcohol damage. A double-blind, randomized, cross-over study was performed on eight healthy adult men. After an overnight fast, a gastroscope was inserted and the antral mucosa was sprayed with a 10-mL test solution containing either enprostil (70 micrograms) or its vehicle (control). After 15 minutes, mucosal injury was scored (0-5), and the mucosa was sprayed with 100 mL 80% ethanol. Mucosal injury was scored after a further 15, 20, 25, and 30 minutes. The entire experiment was recorded on video film, which a second endoscopist used to score the damage independently. The two experiments were separated by an interval of 1 week. There was close agreement between the two endoscopists (r = 0.9385), and their scores were averaged. Using Friedman's two-way analysis of variance, a highly significant (P less than 0.00004) increase in injury was demonstrated following enprostil pretreatment. The Wilcoxin signed rank test showed the differences to be significant (P less than 0.05) at every time point. We conclude that enprostil, rather than protecting the human antral mucosa from alcohol injury, appears to potentiate this injury and may itself be damaging in therapeutic concentrations. This unexpected result cannot yet be explained but demands caution in the clinical use of enprostil.

A report of three multiclinic trials evaluating arbaprostil in arthritic patients with ASA/NSAID gastric mucosal damage. The Upjohn Company Arbaprostil ASA/NSAID Gastric Mucosal Damage Treatment Study Groups

Three randomized, placebo-controlled multiclinic trials involving arbaprostil dosages of (a) 10 micrograms; (b) 25 micrograms; and (c) 10, 25, or 50 micrograms orally for 4 wk in patients older than 18 yr with rheumatoid arthritis or osteoarthritis who had endoscopically documented nonsteroidal antiinflammatory drug-associated gastric mucosal damage were conducted in the United States. All patients continued taking the nonsteroidal antiinflammatory drugs and were reendoscoped after 4 wk of therapy. Success at that time was defined as complete resolution of all gastric mucosal damage. Six hundred fifty-eight patients were enrolled in the three trials. Significantly more patients experienced healing in the arbaprostil treatment groups in all trials compared with those who received placebo. The healing rates in the various trials were 68% and 32% (10 micrograms vs. placebo; p = 0.007); 77% and 23% (25 micrograms vs. placebo; p less than 0.001); and 52%, 46%, 35%, and 16% (50, 25, and 10 micrograms vs. placebo; p less than 0.001, less than 0.001, and 0.002, respectively). Diarrhea, mostly of a mild nature, was the only arbaprostil-associated side effect and was found with the 25- and 50-microgram dosages (33% and 59%, respectively). No exacerbation of arthritis signs or symptoms was found. Arbaprostil at doses with varying effects on gastric acid secretion (25 and 50 micrograms) was documented in these trials to be an effective and safe agent for healing gastric mucosal damage associated with aspirin or other nonsteroidal antiinflammatory drugs in patients with either rheumatoid arthritis or osteoarthritis without adversely affecting joint symptomatology.

Effect of acute and chronic alcohol feeding on prostaglandin E2 biosynthesis in rat stomach

The effect of acute and chronic alcohol ingestion on gastric prostaglandin E2 synthesis and the PGE2 content in the stomach was studied in rats. Up to 8 hr following a single oral load of 20% alcohol (v/v; 4 g/kg body weight), the PGE2 synthesis in isolated microsomes from rat stomach remained unchanged as compared with control values. Feeding a liquid alcohol-containing diet (37% of total Joules) for 1, 6, or 12 weeks significantly decreased the rate of PGE2 synthesis (percentage inhibition as compared with control values 39, 27, and 57, respectively). In addition, chronic alcohol feeding led to a drop in the tissue content of PGE2, the decrease being more pronounced after 6 (-49%) and 12 (-58%) weeks than after 1 week (-24%). The results suggest that the inhibition of endogenous PGE2 synthesis in the stomach following ingestion of appreciable quantities of alcohol might play a role in the pathogenesis of alcohol-induced injury of the gastric mucosa.

Aspirin-induced human antral injury is reduced by vodka pretreatment

Mild irritants have been shown to protect the rat gastric mucosa against noxious agents. This study was designed to test the protective potential of low-dose ethanol against acetylsalicylic acid (ASA) -induced gastric injury. Ten healthy volunteers who were nondrinkers and had normal baseline upper gastrointestinal endoscopy participated in a randomized double-blind crossover study. Thirty minutes after either vodka (37.5 ml) in tomato juice or tomato juice alone, each subject took 975 mg ASA and then underwent endoscopy 1 hr later. The degree of mucosal injury was scored, and blood was taken for ethanol and salicylate levels. There was a washout interval of seven days between the two treatments. Endoscopic scores were analyzed using the sign test. After a single dose of ASA, mucosal injury was confined to the fundus and antrum, while the duodenum was minimally affected. A significant reduction in antral damage was seen with ethanol pretreatment (P less than 0.05). The same trend was evident in the fundus but did not achieve statistical significance. Serum salicylate levels averaged 13.2 +/- 0.8 mg/100 ml and were not different between the two treatments. Ethanol concentration ranged from 1.1 to 6.2 mmol/liter following the vodka drink and was 0 after the placebo.

Review: acute human models of gastric mucosal injury

The use of acute human models of gastric mucosal injury has been stimulated by a need to understand more fully the problems of non-steroidal anti-inflammatory drugs but such models have other applications. None is ideal and they all share certain drawbacks. For none of them has a precise relationship to clinical events been established and they have all tended to be employed on a population of young healthy subjects who are not those at greatest clinical risk. Of individual methods mucosal potential difference is an indirect measure which is too often affected by other influences to be acceptable as a measure of mucosal injury when used alone, although it has some value as an adjunct to other measurements. Assay of DNA in gastric washings is a suitable technique for quantifying desquamation of gastric epithelial cells occurring in response to acute injury; on present evidence its significance is much more difficult to assess in the context of continuing challenge over several days. By contrast, measurement of microbleeding is more suitable for quantifying injury over several days of NSAID ingestion; little bleeding is recorded with a single acute challenge. Endoscopy can demonstrate macroscopic lesions which result from mucosal injury--injury which is quantified more easily and sensitively by measurements of cellular exfoliation or bleeding. Paradoxically, endoscopy's strength has been to underline the scientific weakness of acute models because it shows that it is rare for ulcers, which are the lesions of clinical concern to develop in these studies.

Prostaglandin E2 directly protects isolated rat gastric surface cell membranes against bile salts

Rat gastric surface cell membranes were prepared and the effect of taurocholic acid assessed by ESR spectroscopy using the 16-doxylstearic acid spin label. Taurocholic acid increased the polar part of the spectra, indicating an augmented amount of spin label molecules with a polar environment. Concomitantly, mobility of the spin label molecule was augmented. The effect of taurocholic acid was completely prevented by the previous addition of prostaglandin E2. This suggests a direct protective efficiency of prostaglandin E2 on rat gastric surface cell membranes without the metabolic participation of intact cells.

Misoprostol. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in the treatment of peptic ulcer disease

Misoprostol is an analogue of prostaglandin E1 and is the first synthetic prostaglandin analogue to be made available for the treatment of peptic ulcer disease. It inhibits gastric acid secretion in man, and there is also some evidence that it limits the extent of gastrointestinal damage induced by ulcerogenic agents in animals and healthy volunteers at doses lower than those required to inhibit acid secretion. This 'cytoprotective' activity has been explained by several mechanisms, but its contribution to the clinical efficacy of misoprostol in healing established ulcers is doubtful since the drug does not appear to be effective in healing peptic ulcers at non-antisecretory dosages. In clinical trials, ulcer healing has been reported in 60 to 85% of patients with duodenal ulcers and 32 to 54% with gastric ulcers receiving misoprostol 200 micrograms 4 times daily for 4 weeks--the recommended dosage. In comparative studies, the percentage of patients with healed ulcers after misoprostol (800 micrograms daily) was not significantly different from that with cimetidine (1200 mg daily), although there was greater pain relief with cimetidine. No study has yet been published concerning the use of misoprostol as maintenance therapy for the prevention of ulcer recurrence, and no long term tolerability data are available. However, in acute ulcer healing studies (2 to 12 weeks in duration) misoprostol has been well tolerated. Diarrhoea was the most commonly reported symptom, and this was only rarely of sufficient severity to interfere with treatment. No evidence of histopathological changes in the gastric mucosa induced by misoprostol have been reported in man. Evidence of uterine stimulant effects in women receiving misoprostol during the first trimester of pregnancy has resulted in the drug being contraindicated during pregnancy. Thus, misoprostol is a new type of antiulcer drug, providing an alternative approach to the therapy of peptic ulcer disease. It has been shown to be effective and well tolerated in the healing of both gastric and duodenal ulcers. Future studies need to identify the specific types of patients likely to obtain most benefit from treatment, in order to define more clearly the place of misoprostol in the treatment of these indications, as well as addressing the possibility of ulcer prevention with lower doses of misoprostol.

Cytoprotection by a synthetic prostaglandin against ethanol-induced gastric mucosal damage. A double-blind endoscopic study in human subjects

This randomized, double-blind, placebo-controlled study compared the cytoprotective effects of misoprostol, a synthetic analog of prostaglandin E1, and cimetidine on ethanol-induced gastric mucosal damage. Forty-five healthy male subjects were accepted, following endoscopy to exclude those with upper gastrointestinal disease. Injury to the gastric mucosa was induced by spraying it with 80% ethanol solution. Misoprostol (200 micrograms) intragastrically or cimetidine (300 mg) orally or placebo was administrated before the ethanol challenge. The gastric mucosa was graded using a seven-point endoscopic scale by two endoscopists 15 and 30 min after ethanol instillation. Thirty minutes following the instillation of ethanol, the gastric mucosa of placebo-treated subjects showed marked damage, with an endoscopic score (mean +/- standard deviation) of 5.5 +/- 0.9. Cimetidine partially prevented gastric mucosal damage, with an endoscopic score of 4.5 +/- 1.7 as compared to placebo (p = 0.04). Misoprostol significantly prevented gastric mucosal injury with a mean endoscopic score of 1 +/- 1.7 when compared to placebo (p = 0.0001) and to cimetidine (p = 0.0002). This cytoprotective action of misoprostol may prove to be clinically very important and warrants further investigation.

A double-blind study of prophylactic effect of misoprostol on lesions of gastric and duodenal mucosa induced by oral administration of tolmetin in healthy subjects

Tolmetin, a nonsteroidal antiinflammatory drug, is known to induce edema, submucosal hemorrhage, and erosions of the gastrointestinal tract when administered at recommended doses. The purpose of our study was to determine whether misoprostol prevented or reduced the severity of duodenal and gastric mucosal injury induced by tolmetin. Following endoscopic screening, 60 healthy male and female subjects were assigned at random to one of two treatment groups. One group was treated with tolmetin (2000 mg/day, in four divided doses) and misoprostol (200 micrograms four times daily); the other with tolmetin and placebo. Both drugs were administered for six and a quarter days. On the seventh day, 2 hr after the last dose, an endoscopic examination of the gastric and duodenal mucosa was repeated, and the results graded. Subjects with 10 or fewer hemorrhages or erosions were considered treatment successes; those with 11 or more erosions, plus any other lesions, were considered treatment failures. A total of 59 subjects completed the study. One withdrew because of an unsuspected pregnancy. In regard to the gastric mucosa, seven of 29 (24%) placebo subjects were considered treatment successes. In the misoprostol group, 27 of 30 (90%) were treatment successes. This difference is statistically significant at the P less than 0.0001 level. The overall damage to the duodenal mucosa caused by tolmetin is less than that to the gastric mucosa, with the misoprostol-treated subjects having significantly less damage than the placebo subjects (P less than 0.001). Side effects were common in both groups, but almost all were mild, gastrointestinal in origin, and did not require treatment or withdrawal from the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandins and the gastrointestinal mucosa: are they important in its function, disease, or treatment?

In 1971 interest in the role of prostaglandins in the gastrointestinal tract was stimulated by the publication of two hypotheses--that aspirin damaged the gastric mucosa by inhibiting prostaglandin synthesis (1) and that cholera toxin caused diarrhea by stimulating it (2). Subsequent research into the gastrointestinal actions of prostaglandins has been considerable and now impinges on clinical practice. This paper reviews the involvement of prostaglandins and related compounds in mucosal protection, in ulcer healing, in diarrhea, and in gastrointestinal inflammation, with particular reference to the growing body of human data.

Gastrointestinal cytoprotective effects of misoprostol. Clinical efficacy overview

The cytoprotective effects of misoprostol, a synthetic analog of prostaglandin E1, were investigated in healthy human subjects using randomized and placebo-controlled studies. Misoprostol significantly inhibited established aspirin (975 mg q.i.d.)-induced gastric microbleeding at 50 micrograms q.i.d., and to some extent, but not significantly, at 25 micrograms q.i.d. Misoprostol also reduced acid and chloride secretion significantly at 50 micrograms q.i.d., but not at 25 micrograms q.i.d. When administered concurrently with aspirin 650 mg q.i.d., misoprostol 25 micrograms q.i.d. significantly inhibited aspirin-induced fecal blood loss without affecting plasma salicylate concentration. The fact that misoprostol was tested at a sub-therapeutic gastric antisecretory dose (25 micrograms) indicates that the inhibition of fecal blood loss was not due to its gastric antisecretory property. Misoprostol tended to reduce antral erosion and DNA content of gastric fluid, but increased mucus concentrations in subjects with ethanol-induced damage. However, the dose of ethanol used produced gastric damage in only six of the 10 subjects and did not provide a satisfactory baseline. Misoprostol attenuated the drop in transmucosal potential difference induced by sodium taurocholate. It is concluded that misoprostol has cytoprotective activity in man. These effects may be of great importance in the treatment of acid peptic disease of the gastrointestinal tract.

Cytoprotection by prostaglandin occurs in spite of penetration of absolute ethanol into the gastric mucosa

Several prostaglandins are cytoprotective for the stomach; they prevent mucosal necrosis and hemorrhages produced by noxious agents, such as absolute ethanol. One possible mechanism of cytoprotection would be that the prostaglandin may prevent penetration of the necrotizing agent into the gastric mucosa. To test this hypothesis, 2 ml of 100% ethanol containing tracer amounts of 14C at carbon 1 was given orally to rats, after ligating the pylorus. [14C]Ethanol was measured in the gastric mucosa and in plasma from 2.5 to 60 min after ethanol administration. 16,16-Dimethyl prostaglandin E2 was given orally at a cytoprotective dose (10 micrograms/kg) 15 min before 100% ethanol. The level of [14C]ethanol (disintegrations per minute per gram of tissue) in the gastric mucosa of 16,16-dimethyl prostaglandin E2-treated animals were not different from those of control animals. The plasma levels were slightly lower during the first 10 min, but the area under the curve for the entire 60 min was the same in both groups. We conclude that (a) 16,16-dimethyl prostaglandin E2 does not prevent entry of ethanol into the gastric mucosa; (b) 16,16-dimethyl prostaglandin E2 protects the cells located deep in the gastric mucosa from necrosis, in spite of the fact that these cells are in contact with as much ethanol as cells of untreated animals; (c) gastric cytoprotection is probably due to a defense mechanism at the cellular level. These findings minimize the importance of luminal factors, such as an increase in mucus or bicarbonate, in the mechanism of cytoprotection.

Protection of rat gastric mucosa against ethanol injury by the new synthetic prostaglandin MDL 646

Oral administration to fasted rats of absolute ethanol produces extensive necrotic lesions of gastric mucosa as well as a massive leakage of proteins and mucus glycoproteins into gastric lumen. When the new synthetic prostaglandin MDL 646, belonging to the PGE1 series, is administered intragastrically (2 or 10 micrograms/kg) 30 min before ethanol administration, a significant protection of rat gastric mucosa against alcohol injury is observed.