Effects of misoprostol, (+/-)-methyl (11 alpha, 13E)-11, 16-dihydroxy-16-methyl-9-oxoprost-13-en-l-oate, on various gastric and duodenal lesions in rats

Male Sprague-Dawley rats (230-280 g), either fasted for 15-24 hr or non-fasted prior to experiments, were used. Misoprostol (3-100 micrograms/kg, p.o.) dose-dependently inhibited the development of 150 mM HCl X aspirin (100 mg/kg)-, 150 mM HCl X 60% ethanol-, and aspirin (150 mg/kg)-induced gastric lesions. Misoprostol (30, 100 micrograms/kg, p.o.), given twice daily for 4 days, significantly inhibited prednisolone (50 mg/kg given once daily for 4 days)-induced gastric lesions. Misoprostol (30 or 2 X 300 micrograms/kg, p.o.) also significantly inhibited water-immersion stress (21 degrees C, 10 hr)-induced gastric lesions or mepirizole (200 mg/kg)-induced duodenal lesions, respectively. In contrast, misoprostol (30-300 micrograms/kg, p.o.) had no effects on indomethacin (25 mg/kg)- and mepirizole (200 mg/kg)-induced gastric lesions. Misoprostol (30 micrograms/kg, p.o.) had no effect on gastric secretion in pylorus-ligated preparations (4 hr), but it (100 or 300 micrograms/kg, p.o.) significantly increased the volume and pepsin output. Gastric motility, either normal or enhanced with indomethacin (25 mg/kg), was inhibited by misoprostol (30 or 300 micrograms/kg, p.o.). Misoprostol (30 micrograms/kg, i.d.) significantly stimulated duodenal HCO3- secretion. Mechanisms by which misoprostol inhibits various gastric lesions remain unknown. However, the stimulatory activity on duodenal HCO3- secretion appears to be involved in the preventive effect of misoprostol on the development of duodenal lesions. The effects of cimetidine and 16,16-dimethyl PGE2 were also studied and compared with those of misoprostol.     

Effects of nizatidine, a new histamine H2-receptor antagonist, on gastric acid secretion and various gastric and duodenal lesions in rats: comparison with cimetidine

We examined the antisecretory and antilesion activities of nizatidine in rats. Male SD or Donryu rats (200-260 g) were used under fasted or fed conditions. Nizatidine, given orally or parenterally (intraperitoneally, subcutaneously or intraduodenally) at 0.3-150 mg/kg, inhibited both basal (pylorus-ligation preparations) and histamine-stimulated gastric acid secretion (acute fistula preparations) in a dose-dependent manner. The potency of nizatidine was 2 to 8 times greater than cimetidine when the ED50 values (mg/kg or mu mole/kg) of each agent were compared. The antisecretory activity of nizatidine, given orally, persisted for more than 3.5 hr, but disappeared 6 hr later. Nizatidine, given orally or subcutaneously at 0.3-150 mg/kg, prevented development of gastric lesions induced by water immersion, pylorus ligation (Shay), histamine, aspirin, or indomethacin in a dose-dependent manner. Duodenal ulcers induced by mepirizole were also markedly prevented with nizatidine. The potency of nizatidine on stress lesions or duodenal ulcers was about 20 or 14 times greater than that of cimetidine, respectively. Nizatidine, given orally 3 times a day for 4 weeks, significantly (P less than 0.05) accelerated the healing of acetic acid-induced gastric ulcers which were delayed by prolonged treatment with indomethacin. These results suggest that nizatidine is a useful drug for the treatment of peptic ulcers in man.     

Augmentation of cysteamine and mepirizole-induced lesions in the rat duodenum and stomach by histamine or indomethacin

Repeated administration of histamine X 2HCl (40 mg/kg X 4) significantly augmented mepirizole (200 mg/kg) or cysteamine (300 mg/kg)-induced duodenal and gastric lesions in rats within 6 hr. Most of the duodenal lesions were penetrating ulcers and were located over the entire duodenum. Gastric lesions were mainly located in the antrum adjacent to the duodenum. Indomethacin pretreatment did not significantly augment the duodenal lesions induced by mepirizole or cysteamine, but did augment the gastric lesions induced by these compounds.     

Cytoprotective activity of tiquizium bromide (HSR-902) and its mechanism

The effects of HSR-902, an antimuscarinic agent, on acute gastric mucosal lesions induced by various necrotizing agents, gastric mucus secretion and gastric HCO3- secretion in rats were compared with those of pirenzepine.2HCl (pirenzepine), an antiulcer agent. 1) HSR-902 (10-100 mg/kg), given orally, dose-dependently prevented the gastric mucosal lesions induced by ethanol-HCl (60% ethanol in 150 mM HCl), aspirin-HCl (150 mg/kg of aspirin in 150 mM HCl), 0.6 N HCl and 0.2 N NaOH; and the cytoprotective effects of HSR-902 were almost equal or somewhat more potent than those of pirenzepine. 2) HSR-902 (30 mg/kg, p.o.), like pirenzepine, increased the alcian blue binding to gastric mucosa and both hexosamine and N-acetylneuramic acid in gastric juice and reversed the decrease of alcian blue binding to gastric mucosa in water-immersion stress. 3) HSR-902 (30 mg/kg, p.o.), unlike pirenzepine and atropine sulfate, increased the gastric HCO3- secretion in the pylorus-ligated preparations. 4) The cytoprotective effect of HSR-902 (30 mg/kg, p.o.), when examined using gastric mucosal lesion induced by aspirin-HCl, was not abolished by the pretreatment with indomethacin (10 mg/kg, s.c.) or N-ethylmaleimide (10 mg/kg, s.c.). 5) HSR-902 (30 mg/kg, p.o.) did not influence the gastric mucosal potential difference. These results suggest that HSR-902 is a promising drug for the treatment of gastritis and peptic ulcers.     

Effects of 3-hydroxymethyl-2-methylimidazo [2, 1-b] benzothiazole (NIK-228) on gastric acid secretion and various experimental peptic ulcers in rats

We examined the antisecretory and antiulcer activities of NIK-228 in rats. Male Wistar rats (200 to 250 g) were used under 24 to 48 hr fasted (without water) conditions. NIK-228 and famotidine were administered orally 1 hr before pylorus ligation, stress or each ulceration inducer. Both NIK-228 (10 to 100 mg/kg) and famotidine (0.3 to 3 mg/kg) dose-dependently inhibited gastric secretion in pylorus ligated rats. Water-immersion stress-, indomethacin- or pylorus ligation (Shay)-induced gastric ulcers were dose-dependently inhibited by NIK-228 (10 to 100 mg/kg), but only water-immersion stress and indomethacin induced ulcers were dose-dependently inhibited by famotidine (0.03 to 3 mg/kg). Ethanol- and 0.6 N HCl-induced gastric lesions were remarkably inhibited by NIK-228 (ED50 = 2.7 and 5.6 mg/kg), but tended to be inhibited also by famotidine (0.3 to 3 mg/kg). Cysteamine-induced duodenal ulcer was inhibited significantly by NIK-228 (30, 100 mg/kg) or famotidine (3 mg/kg). NIK-228 may produce its antiulcer effects via antisecretory and cytoprotective effects. These results suggest that NIK-228 has antisecretory and antiulcer activities.     

Evaluation of tiquizium bromide (HSR-902) as an antiulcer agent

The effects of HSR-902, an antimuscarinic agent, on development of various gastric and duodenal lesions, gastric secretion, pupil size and salivation in rats were compared with those of pirenzepine.2HC1 (pirenzepine, antiulcer agent) and timepidium bromide (timepidium, antispasmodic). 1) HSR-902 (10-100 mg/kg), given orally, dose-dependently inhibited the developments of gastric lesions induced by water-immersion stress, aspirin, indomethacin, serotonin and reserpine and duodenal lesions induced by cysteamine and mepirizole. The activities of HSR-902 were almost equal or somewhat more potent than those of pirenzepine, and they were more potent than those of timepidium. 2) HSR-902 (30 and 100 mg/kg, p.o.), when examined using pylorus-ligated preparations, dose-dependently inhibited the gastric acid output, pepsin output, and gastric acid and pepsin concentrations, but did not inhibit the gastric volume (HSR-902, in a higher dose, slightly increased the gastric volume.). Pirenzepine (100 mg/kg, p.o.), like atropine sulfate, inhibited the gastric volume, acid output and pepsin output, but did not inhibit the gastric acid and pepsin concentrations. Timepidium (100 mg/kg, p.o.), however, hardly influenced these parameters except for increasing the gastric volume. 3) HSR-902 (100 mg/kg, p.o.) induced the mydoriasis and inhibited the pilocarpine-induced salivation, and its activities were less potent than those of pirenzepine. These results suggest that HSR-902 is a promising agent for the treatment of peptic ulcer.     

Effects of a proton pump inhibitor, AG-1749 (lansoprazole), on reflux esophagitis and experimental ulcers in rats

The effects of (+/-)-2-[[[3-methyl-4-(2,2,2-trifluoroethoxy-2- pyridyl]methyl]sulfinyl]-1H-benzimidazole (lansoprazole, AG-1749) and famotidine on various experimental ulcers in rats were compared. AG-1749 inhibited reflux esophagitis; gastric lesions induced by water-immersion stress, aspirin or ethanol; and duodenal ulcers induced by cysteamine or mepirizole in a dose-dependent manner: the ID50 values were 0.7, 2.4, 0.7, 8.5, 1.1 and 0.3 mg/kg, p.o. or i.d., respectively. Famotidine inhibited reflux esophagitis with an ID50 value of 12.9 mg/kg, but did not cause 50% inhibition of ethanol-induced gastric lesions even at 100 mg/kg, although it showed almost the same or a little stronger potency on other experimental ulcers: ID50 values were 0.3-1.4 mg/kg. Significant aggravation of ethanol- or water-immersion stress-induced lesions was observed in rats given famotidine at 30 mg/kg twice daily for 4 days, but not in rats given AG-1749 at 10 mg/kg twice daily. Administration of AG-1749 for 14 consecutive days markedly accelerated the healing of acetic acid-induced gastric and duodenal ulcers, and the healing effect was significant at 10 and 30 mg/kg/day, p.o. Famotidine also accelerated the healing of ulcers, but its potency was less than that of AG-1749. The results of this study indicate that although AG-1749 is slightly less potent than famotidine in inhibiting acutely induced gastroduodenal lesions, this agent is superior to famotidine in promoting the healing of ulcers and in inhibiting reflux esophagitis and ethanol-induced gastric lesions.     

Antiulcer effect of (-)-cis-2,3-dihydro-3-(4-methylpiperazinylmethyl) -2-phenyl-1,5-benzothiazepin-4-(5H)-one hydrochloride (BTM-1086) in experimental animals

Effects of (-) cis-2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5-benz othiazepin-4-(5H ) -one hydrochloride (BTM-1086) on various experimental gastric and duodenal ulcers were studied in rats. In the pylorus-ligated ulcer, restraint and water immersion stress ulcer, and drug-induced ulcer (indomethacin, aspirin, reserpine, serotonin, cysteamine), BTM-1086 prevented the development of ulcer at a dose of 0.1 to 1 mg/kg, p.o., but only weakly inhibited the histamine-induced gastric ulcer. The inhibitory activities of BTM-1086 were significantly higher than those of atropine sulfate. In the healing experiment with the acetic acid-induced stomach ulcer, BTM-1086 (1 mg/kg/day, p.o., X 14) showed a significant healing effect, which was higher than that of propantheline bromide. BTM-1086 at a dose of 0.2 mg/kg, i.d., remarkably inhibited the gastric secretion 6 hr after pylorus ligation. The aspirin-induced reductions of the total acid and K+ as well as the increments of the volume and Na+ in the gastric secretion were prevented dose-dependently by pretreatment with BTM-1086.     

Anti-ulcer actions of phytosphingosine hydrochloride in different experimental rat ulcer models

The gastroprotective activity of phytosphingosine hydrochloride (PS-HCl, CAS 554-62-1) was assessed in four different rat models of experimentally induced gastric ulcer. Various doses (2.5-10 mg/kg) of PS-HCI were orally administered to rats 30 min before the treatment with HCl/ethanol, indometacin, cysteamine, or to rats with ligated pylorus. Oral administration of PS-HCl (2.5-10 mg/kg) to rats prevented the acute ulcer formation in 4 different types of ulcer in a dose-dependent manner as follows: (1) HCl/ethanol-induced gastric mucosal membrane lesions (20.1-47.8% inhibition), (2) indometacin-induced gastric mucosal membrane lesions (4.6-31.9% inhibition), (3) duodenal ulcer induced by cysteamine (10-20% inhibition), (4) gastric secretion and ulceration following pylorus ligation (33.3-61.9% inhibition). These results indicate that PS-HCI may be useful for the prevention of gastric ulcer.     

Antiulcer activity of cod liver oil in rats

Objective:

Cod liver oil is used widely as a dietary supplement. The present study was carried out to evaluate the effect of cod liver oil (0.5 g/kg, p.o. and 1 g/kg, p.o.) on gastric and duodenal ulcers.

Materials and Methods:

The study was carried out on different gastric ulcer models such as acetic acid induced chronic gastric ulcers, pylorus ligation, indomethacin induced ulcers, stress induced ulcers and ethanol induced ulcers. The duodenal ulcers were induced using cysteamine hydrochloride (HCl). Ranitidine (50 mg/kg p.o.) and misoprostol (100 µg/kg, p.o.) were used as standard drugs.

Results:

Both doses of cod liver oil showed gastric ulcer healing effect in acetic acid induced chronic gastric ulcers, produced gastric antisecretory effect in pylorus-ligated rats and also showed gastric cytoprotective effect in ethanol-induced and indomethacin-induced ulcer. Cod liver oil also produced a significant reduction in the development of stress induced gastric ulcers and cysteamine induced duodenal ulcer. The high dose of cod liver oil (1 g/kg, p.o.) was more effective compared to the low dose (0.5 g/kg, p.o.).

Conclusion:

Cod liver oil increases healing of gastric ulcers and prevents the development of experimentally induced gastric and duodenal ulcers in rats.     

Pathogenic mechanisms involved in mepirizole-induced duodenal damage in the rat

Mepirizole (60 and 200 mg/kg) administered s.c. induced damage in the surface epithelial cells of the rat proximal duodenum as early as 2 hr after the treatment. 16,16-Dimethyl prostaglandin E2 (dmPGE2, 30 micrograms/kg) administered s.c. significantly protected the duodenal mucosa against mepirizole-induced damage for up to 6 hr. Gastric acid secretion in acute fistula preparations was significantly reduced 1 hr after administration of mepirizole (60 and 200 mg/kg). The secretion reverted to the control level 2 hr later. In the 60 mg/kg-treated group, however, there was a significant increase in the acid output for up to 6 hr. Duodenal HCO3- secretion, stimulated with 10 mM HCl was significantly inhibited with mepirizole (60 and 200 mg/kg). Mepirizole (60 and 200 mg/kg) significantly increased the amount of acid in the duodenum for 2 to 6 hr after the treatment. dmPGE2 (30 micrograms/kg) significantly inhibited gastric acid secretion, stimulated duodenal HCO3- secretion, and reduced the increased amount of acid in the duodenum in response to mepirizole. Endogenous prostaglandin E2 and 6-keto prostaglandin F1 alpha in the duodenal mucosa were significantly reduced by mepirizole (200 mg/kg) 1 to 2 hr later. Mepirizole-induced duodenal damage appears to be caused by the increased amount of acid in the duodenum.     

Gastroprotective activity of oleanolic acid derivatives on experimentally induced gastric lesions in rats and mice

The gastroprotective effect of the triterpene oleanolic acid (OA) was assessed on gastric ulceration in rats. The effect of a single oral dose of OA was evaluated at 50, 100 and 200 mg kg(-1) in the following models: pylorus ligature (Shay), and aspirin- and ethanol-induced gastric ulcers. A single oral administration of OA at doses of 50, 100 and 200 mg kg-' inhibited the appearance of gastric lesions induced by ethanol, aspirin and pylorus ligature. In the pylorus ligature and aspirin models, the effect of OA at the selected concentrations was comparable with that of ranitidine at 50 mg kg(-1). In the ethanol-induced gastric lesion model, OA showed a dose-dependent activity, and at 100 and 200 mg kg(-1) was as active as omeprazole at 20 mg kg(-1). The effect of OA, its acetylated and methoxylated derivatives, oleanonic acid and its methyl ester were assessed on HCI/ethanol-induced ulcers in mice at 200 mg kg(-1). OA and its methoxylated (OAM) and acetylated (OAAM, OAA) derivatives proved to be active in this animal model. The semisynthetic derivatives OAM and OAAM had the greatest gastroprotective activity, but their effect was not significantly greater than OA. In an acute toxicity test on mice, intraperitoneal administration of OA showed no toxicity at doses up to 600 mg kg(-1).     

Lack of cytoprotection by acetaminophen against ethanol-, HCl.ethanol- and HCl.aspirin-induced gastric mucosal lesions in rats

Effects of acetaminophen against gastric mucosal lesions induced by three different necrotizing agents were studied. Acetaminophen (30, 100 mg/kg), given p.o. 0.5 hr before absolute ethanol, HCl . ethanol, or HCl . aspirin administration, afforded no cytoprotection against gastric mucosal lesions induced by the above agents in 24 hr fasted rats. However, 16,16-dimethyl prostaglandin E2 (3 micrograms/kg), given p.o. 0.5 hr before these necrotizing agents, completely prevented development of these lesions.     

Gastric antisecretory and anti-ulcer effect of ME3407, a new benzimidazole derivative, in rats

The effects of a new benzimidazole derivative, ME3407 (n-butyl-2-(thiazolo-[5,4-b]pyrid-2-yl) sulfinylacetate, CAS 133903-90-9), on gastric acid secretion and gastric and duodenal ulcers in rats were examined. ME3407, given orally, inhibited dose-dependently (0.3-30 mg/kg) the incidence of gastric lesions such as Shay ulcers, and water-immersion stress-, acetylsalicylic acid (ASA)- and histamine-induced erosions. In addition, ME3407 showed marked therapeutic effect on HCl- and ASA-induced lesions. In the lumen-perfused rats, oral administration of ME3407 inhibited dose-dependently (1-100 mg/kg) gastric acid secretion induced by histamine and tetragastrin with ED50 values of 3.02 and 3.37 mg/kg, respectively. Oral administration of ME3407 at a dose of 30 mg/kg also inhibited the elevation of serum gastrin level. The development of duodenal ulcers caused by mepirizole and systeamine was also potently inhibited by ME3407 at an oral dose of 0.1-30 mg/kg. However, when given at 30 mg/kg intraduodenally, subcutaneously or intravenously, ME3407 did not inhibit these acutely induced gastric elosion and acid output. ME3407 was not detected in the serum upon oral administration. These results indicated that ME3407 was active only by oral administration, and exerts direct action on the ulcers and acid secretion from the gastric membrane.     

Cytoprotective action of mast cell stabilizers against ethanol-induced gastric lesions in rats

We examined the effects of FPL-52694 and disodium cromoglycate (DSCG), mast cell stabilizers, on HCl X ethanol-induced gastric lesions in rats and investigated the factors involved in their protection. Oral (p.o.) administration of 1 ml of HCl X ethanol (60% in 150 mM HCl) induced linear hemorrhagic lesions in the gastric mucosa within 1 hr. FPL-52694 (1-30 mg/kg), given both p.o. and intraperitoneally (i.p.), prevented these lesions in a dose-related manner. DSCG (3-30 mg/kg) also dose-dependently reduced the formation of these lesions when this agent was given i.p. The protective effects of these drugs on HCl X ethanol-induced lesions were significantly attenuated by pretreatment with indomethacin (5 mg/kg, s.c.). Both gastric acid secretion and transmucosal potential difference were significantly reduced by topical application of FPL-52694 (greater than 10 mg/kg), but were not affected by i.p. administration of FPL-52694 and DSCG. On the other hand, gastric motor activity measured as intraluminal pressure recordings was significantly inhibited for 2 hr by both FPL-52694 (p.o. and i.p.) and DSCG (i.p.), and these effects were also significantly antagonized with prior administration of indomethacin. A significant relationship was found between the effects of these two drugs on the lesion index and the motility index (r: 0.9214, P less than 0.01), but not other factors. These results suggest that mast cell stabilizers such as FPL-52694 and DSCG protect the gastric mucosa against HCl X ethanol through a systemic action, probably mediated with endogenous prostaglandins. Although the mechanism of cytoprotection remains unknown, this property may be related to their inhibitory effects on gastric motor activity.     

Effects of IGN-2098, a new histamine H2-receptor antagonist, on gastric secretion and gastric and duodenal lesions induced in rats. Comparison with roxatidine]

A new compound, IGN-2098 [5,6-dimethyl-2-[4-<3-(1-piperidinomethyl) phenoxy>cis-butenylamino]-4-(1H)-pyrimidone.2HCl], was found to be a potential histamine H2-receptor antagonist in the guinea pig atrium. IGN-2098, given p.o., significantly and persistently (for more than 12 hr) inhibited the basal gastric secretion in pylorus-ligated rats. The agent also significantly inhibited the basal gastric secretion when given by the s.c.-, i.d.- or i.p.-route. Stimulated gastric secretion in fistula rats in response to histamine, carbachol or pentagastrin was also significantly inhibited with IGN-2098 given s.c. Pretreatment with IGN-2098 (p.o.) significantly protected the gastric mucosa against pylorus ligation-, water-immersion stress-, histamine-, indomethacin-, HCl.aspirin-, and HCl.ethanol-induced gastric lesions. In addition, the agent significantly protected the duodenal mucosa against mepirizole-induced ulcers. Based upon the ED50 values, the antisecretory effects on histamine, carbachol or pentagastrin-stimulated acid secretion were 6.0, 37.0 or 80 times more potent than roxatidine, respectively. As to the anti-lesion effects on HCl.aspirin-induced gastric lesions or mepirizole-induced duodenal ulcers, IGN-2098 was 8.1 or 14.8 times more potent than roxatidine, respectively. These results suggest that IGN-2098 will be a useful drug for the treatment of gastric and duodenal lesions in man.     

The relationship of intraduodenal pH and delayed gastric emptying in duodenal ulceration induced by mepirizole or cysteamine in rats

Subcutaneous administration of mepirizole (60 and 200 mg/kg) and cysteamine (100 and 300 mg/kg) to fasted rats consistently induced localized villous damage to the proximal duodenum after 6 to 8 hr. The severity of the damage in animals treated with the low doses remained unchanged at 12 hr. With the high doses, however, well-defined deep ulcers were evident by that time, the incidence being high. The agents caused a significant accumulation of highly acidic gastric contents for 6 to 8 hr, but the accumulated gastric contents had markedly decreased by 12 hr. The intraduodenal pH in these animals was significantly lowered for 8 hr with the low doses, but for 12 hr with the high doses. Both mepirizole and cysteamine significantly delayed gastric emptying which was quantitated by weighing the food residue in refed animals. This delay in emptying was observed for 6 to 8 hr with the low doses and for 12 hr with the high doses. We conclude that this prolonged accumulation of gastric contents for up to 8 hr, resulting in a continuous lowering of the intraduodenal pH for 12 hr, is a crucial factor for the progression from duodenal villous damage to visible ulcers in response to mepirizole and cysteamine.     

Effects of 12-sulfodehydroabietic acid monosodium salt (TA-2711), a new anti-ulcer agent, on gastric secretion and experimental ulcers in rats

Effects of 12-sulfodehydroabietic acid monosodium salt (TA-2711), a new anti-ulcer agent, on gastric secretion and experimental ulcers were investigated in rats. Oral administration of TA-2711 at doses of 25 to 100 mg/kg immediately after pyloric ligation markedly reduced pepsin activity and slightly lowered acid concentration without affecting the volume of gastric juice. Addition of TA-2711 (0.25-16 mg/ml) directly to gastric juice also reduced pepsin activity in vitro. Oral TA-2711 dose-relatedly inhibited the formation of pylorus-ligated ulcers (50-200 mg/kg), aspirin-induced gastric erosions (25-100 mg/kg) and cysteamine-induced duodenal ulcers (100-800 mg/kg). In addition, this drug prevented both the formation of gastric lesions (6.3-100 mg/kg, p.o.) and the fall in gastric potential difference (100 mg/kg, p.o.) induced by ethanol. The preventive effect against ethanol-induced lesions was suppressed by pretreatment with indomethacin (10 mg/kg, s.c.). Intravenous dosing of TA-2711 (10-100 mg/kg) never produced such effects on ethanol-induced lesions and pepsin activity as observed by oral administration. These results indicate that TA-2711 exerts its anti-ulcer effect by a local action, and it is suggested that both reduction of pepsin activity and a mucosal prostaglandin-mediated process are involved in the anti-ulcer action of TA-2711.     

Effects of allyl isothiocyanate from horseradish on several experimental gastric lesions in rats

Allyl isothiocyanate is well known to be a principal pungent constituent of horseradish and an agonist for transient receptor potential (TRP) A1. Ally isothiocyanate markedly inhibited the formation of gastric lesions induced by ethanol (1.5 ml/rat, p.o.), 0.6 M HCl (1.5 ml/rat, p.o.), 1% ammonia (1.5 ml/rat, p.o.), and aspirin (150 mg/kg, p.o.) (ED(50)=1.6, 2.2, 1.7, ca. 6.5 mg/kg, p.o.). It also significantly inhibited the formation of gastric lesions induced by indomethacin (20 mg/kg, p.o.), though the inhibition was ca. 60% at a high dose (40 mg/kg, p.o.). Furthermore, several synthetic isothiocyanate compounds also significantly inhibited ethanol and indomethacin-induced gastric lesions. Whereas, TRPV1 agonists, capsaicin and piperine, inhibited gastric lesions induced by ethanol, 1% ammonia, and aspirin, but had less of an effect on 0.6 M HCl-induced gastric lesions. With regard to mode of action, the protective effects of ally isothiocyanate on ethanol-induced gastric lesions were attenuated by pretreatment with indomethacin, but not with N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME), or ruthenium red. Pretreatment with indomethacin reduced the protective effects of piperine, and L-NAME reduced the effects of capsaicin and omeprazole. Furthermore, ruthenium red reduced the effects of capsaicin, piperine, and omeprazole. These findings suggest that endogenous prostaglandins play an important role in the protective effect of allyl isothiocyanate in ethanol-induced gastric lesions different from capsaicin, piperine, and omeprazole.     

Effects of a new histamine H2-receptor antagonist, ranitidine, on experimental acute gastric and duodenal ulcers (author's transl)

Ranitidine at 100 to 200 mg/kg (i.d. or p.o.) potently inhibited the development of Shay ulcers, indomethacin- or phenylbutazone-induced gastric ulcers and histamine-carbachol-induced duodenal ulcers in rats. Ranitidine at 100 mg/kg (p.o.) also inhibited the development of water-immersion stress-induced gastric ulcers in rats, histamine-induced gastric and duodenal ulcers in guinea pigs, even though the inhibition rate remained within 70%. At that time, the gastric acid output in guinea pigs was reduced with some doses of the drug. Cimetidine at 100 to 200 mg/kg (p.o.) also inhibited the development of indomethacin-, phenylbutazone-, and water-immersion stress-induced gastric ulcers in rats and histamine-induced gastric and duodenal ulcers in guinea pigs. Shay ulcers and histamine-carbachol-induced duodenal ulcers in rats were not affected by cimetidine. Both ranitidine and cimetidine inhibited the gastric acid output in pylorus-ligated rats (7 hr); the maximal inhibition being 79.6% and 50.7% respectively. The mechanism by which ranitidine inhibits various experimental ulcers might be mainly the inhibition of gastric secretion. Gefarnate at 300 mg/kg (p.o.) significantly inhibited phenylbutazone-induced gastric ulcers in rats but had no effect on other ulcer models.