Effects of KT1-32 on acute gastric lesions and duodenal ulcers induced in rats

We studied the effects of KT1-32 (sodium guaiazulene 3-sulfonate) on development of various acute gastric lesions and duodenal ulcers induced in rats. Male Donryu or Sprague-Dawley rats (220-270 g), fasted (but allowed free access to water) for 24 or 48 hr before the experiments, were used. KT1-32 (dissolved in distilled water, 10-100 mg/kg), given p.o. or intraduodenally (i.d.), dose-dependently inhibited the development of gastric lesions induced by HCl X ethanol (60% ethanol in 150 mM HCl), HCl X aspirin (aspirin 100 mg/kg in 150 mM HCl) or aspirin (150 mg/kg in pylorus-ligated preparation) and Shay ulcers (14 hr pylorus ligation). KT1-32 (30 and 100 mg/kg), given p.o. twice (9.5 hr apart), significantly inhibited the development of duodenal ulcers induced by mepirizole (200 mg/kg, s.c.), but did not inhibit gastric lesions developed simultaneously. KT1-32 (30 and 100 mg/kg), given p.o. or i.d., significantly reduced gastric acid secretion when examined using pylorus ligation preparations. KT1-32 (100 mg/kg, i.d.) had no effect on basal and suppressed duodenal HCO3- secretion by mepirizole. These results suggest that KT1-32 is a promising drug for the treatment of gastritis and peptic ulcers.     

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.     

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 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.     

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.     

Effects of prostaglandin biosynthesis inhibitors and ouabain on duodenal mucosa and HCO3- secretion in rats

A single injection (s.c.) of prostaglandin biosynthesis inhibitors such as indomethacin (5 mg/kg), aspirin (200 mg/kg) and quinacrine (100 mg/kg) or a Na+.K+ ATPase inhibitor such as ouabain (10 mg/kg) significantly reduced the adaptive increase of HCO3- output caused by acid in the duodenum of anesthetized rats. These agents had no effect on basal duodenal HCO3- secretion and histamine-stimulated gastric acid secretion. Either of these agents, when given alone, had no effect on the duodenal mucosa of conscious rats, but produced damage in the proximal duodenum within 8 hr when given together with histamine (40 mg/kg X 3, s.c., every 2.5 hr). A significant relationship was found between the degrees of inhibition of acid-induced HCO3- output and the severity of duodenal lesions induced by these drugs (r = 0.8620, P less than 0.01). These results suggest that an impairment of the mechanisms related to acid-induced HCO3- secretion may be particularly relevant to the pathogenesis of duodenal lesions.     

Effects of a gastric antisecretory-cytoprotectant 2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile (Sch 28 080) on cysteamine, reserpine and stress ulcers in rats

Prostaglandin E2 and carbenoxolone, putative cytoprotective agents, were tested in cysteamine, reserpine and stress ulcers in rats. In cysteamine-induced duodenal ulcer, PGE2 was inactive at 0.1 and 0.5 mg/kg p.o.; carbenoxolone at 100 mg/kg p.o. decreased the incidence but not the severity of the ulcer. PGE2 at 5.0 mg/kg p.o. and carbenoxolone at 300 mg/kg p.o. showed moderate effects, but the dosage also inhibited cysteamine-stimulated acid secretion. PGE2 (0.1 and 0.3 mg/kg p.o.) was inactive and carbenoxolone (100 and 300 mg/kg p.o.) further aggravated the gastric ulceration caused by reserpine or cold-restraint stress. In contrast, atropine (3 and 10 mg/kg p.o.) and cimetidine (30, 100 and 300 mg/kg p.o.) were active in all three ulcer models. But the results with cimetidine in stress ulcer were somewhat variable. 2-methyl-8-(phenylmethoxy) imidazo [1,2-a] pyridine-3-acetonitrile (Sch 28 080), a novel structure with both cytoprotective and antisecretory activity, was highly efficacious in cysteamine, reserpine and stress ulcers (1-30 mg/kg p.o.), which was presumably adequately accounted for by its potent antisecretory activity. It is concluded that cysteamine, reserpine and stress ulcers may not be appropriate models for testing the potential antiulcer effect of primarily cytoprotective compounds.     

Effects of MCI-727, a new antiulcer agent, on various gastric and duodenal lesions in experimental animals

Effects of a new antiulcer drug, MCI-727, on gastric and duodenal lesions, gastric secretion and gastric motility were studied in comparison with cimetidine and teprenone. MCI-727 dose-dependently (3-100 mg/kg, p.o. or i.d.) inhibited the development of acute gastric or duodenal lesions such as pyrolus ligation-, water-immersion stress-, indomethacin-, HCl-, HCl-ethanol-induced gastric lesions and cysteamine-induced duodenal lesions in rats and histamine-induced duodenal lesions in guinea pigs. These antiulcer effects exceeded those of cimetidine or teprenone. Repeated administration of MCI-727 (0.3-3 mg/kg/day, p.o., for 10 days) significantly promoted the spontaneous healing of acetic acid-induced chronic gastric ulcers. Concerning gastric acid secretion, MCI-727 selectively inhibited tetragastrin-stimulated acid secretion without effecting basal acid secretion and acid secretion by other stimuli. Cimetidine and teprenone inhibited acid secretion in several cases. MCI-727 and teprenone had inhibitory effects on gastric motility, although cimetidine had no effect. These results suggest that MCI-727 has a wide spectrum of antiulcer activity, and its mode of antiulcer action is different from that of cimetidine or teprenone.     

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 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.     

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.     

Effects of the novel anti-ulcer agent 1-(5'-oxohexyl)-3-methyl-7-propyl xanthine on experimental ulcers and gastric secretion in rats

The effects of 1-(5'-oxohexyl)-3-methyl-7-propyl xanthine (HWA 285) on various experimentally induced ulcers and gastric acid secretion were investigated in rats. HWA 285 (10-50 mg/kg, p.o.) inhibited restraint and water-immersion-induced stress, ulcers, indometacin- and absolute ethanol-induced gastric ulcers and mepirizole-induced duodenal ulcers in rats in a dose-dependent manner. HWA 285 (10-25 mg/kg i.d.) had inhibitory effects on acetylsalicylic acid-induced ulcers. The healing of acetic acid-induced chronic ulcers was significantly accelerated by HWA 285 (25 mg/kg p.o.) when it was given twice daily for 7 consecutive days. When given orally (twice a day, 11 doses in total) before the induction of gastric ulcers by stress, cimetidine at 100 mg/kg aggravated the ulcers, whereas, HWA 285 at 25 mg/kg had not such an effect. In conscious pylorus-ligated rats, HWA 285 (10-100 mg/kg i.p.) showed a dose-dependent inhibition on basal and desglugastrin- and 2-deoxy-D-glucose (2-DG)-stimulated gastric acid secretion. In stomach-lumen perfused rats, HWA 285 (30 mg/kg i.v.) inhibited 2-DG-stimulated gastric acid secretion but not carbachol-stimulated gastric acid secretion. These results suggest that the anti-ulcer effects of HWA 285 are produced by cytoprotective and central anti-secretory activity without peripheral anti-cholinergic properties. Whether the central anti-secretory effects of HWA 285 play thereby the key role, have to be clarified in further investigation.     

Effects of S-0509, a novel CCKB/gastrin receptor antagonist, on acid secretion and experimental duodenal ulcers in rats

Background:

S-0509, 2-[(tert-butoxycarbonylmethyl) [(m-(carboxy-phenyl)-ureidomethyl-carbonyl]] aminobenzo phenone, was developed as a potent and selective CCK_B/gastrin receptor antagonist that does not affect the central nervous system.

Methods:

We evaluated the effects of S-0509 on gastric acid secretion and duodenal ulcerogenic and healing responses in rats comparing it with L-365,260, another CCK_B/gastrin receptor antagonist.

Results:

S-0509 (0.1~10 mg/kg, i.d.) was able to dose-dependently decrease basal acid secretion and inhibit the acid secretory responses induced by both pentagastrin (60 μg/kg/h, i.v.) and peptone (10%, i.g.) but not histamine (4 mg/kg/hr, i.v.) or carbachol (60 μg/kg/h, i.v.). L-365,260 (10 and 30 mg/kg, i.d.) caused only partial a suppression of the acid secretory response to pentagastrin but not to other stimuli, including peptone treatment. On the other hand, a duodenal ulcerogen, mepirizole (200 mg/kg, s.c.) caused an increase in acid secretion and resulted in penetrating ulcers in the proximal duodenum, and these ulcers gradually healed over 3 weeks. S-0509 significantly inhibited both the acid secretory (> 1.0 mg/kg, i.d.) and ulcerogenic (> 3 mg/kg, p.o.) responses induced by mepirizole when it was given as a pre-treatment. It also promoted significantly the healing of these ulcers (> 3 × 2 mg/kg, p.o.) when it was given twice daily for 14 days. In contrast, L-365,260 (30 mg/kg) tended to reduce the severity of mepirizole-induced duodenal ulcers, with a slight inhibition of acid secretion, but it caused no influence on the healing response of these ulcers.

Conclusion:

These results confirmed that S-0509 is a selective CCK_B/gastrin receptor antagonist with potent antisecretory action in vivo conditions, and further demonstrated that this agent not only prevents the development of duodenal ulcers but also shows healing promoting action on duodenal ulcers, probably through the blockade of CCK_B/gastrin receptors.

     

Antithrombotic effect of TRK-100, a novel, stable PGI2 analogue

TRK-100, a stable PGI2 analogue structurally different from carbacyclines, was compared with other antiplatelet drugs for its effect on platelet functions using animal models. TRK-100 (10-300 nM) inhibited rat platelet aggregation induced by ADP (3 microM), collagen (12.5 micrograms/ml) and A23187 (10 microM), and its potency was about 1/3-1/7 that of PGI2. TRK-100 (0.3-3 mg/kg, p.o.) dose-dependently inhibited rabbit platelet adhesion (ED50: 2.2 mg/kg), and its effect lasted over at least 5 hr. In contrast, aspirin and ticlopidine (both at 300 mg/kg, p.o.) showed only a slight inhibition (4-7%). In the thrombocytopenia induced by collagen injection in rats, TRK-100 (3-300 micrograms/kg, i.v.; 0.1-3 mg/kg, p.o.) dose-dependently inhibited a decrease in platelet number, and its ED50 was 0.48-0.62 mg/kg orally and 13.7-16.4 micrograms/kg intravenously, while the inhibition by aspirin and ticlopidine (both at 1000 mg/kg, p.o.) was 40 and 37%, respectively. In the experimental thread thrombosis in rats. TRK-100 (0.03-3 mg/kg, p.o.) dose-dependently inhibited thrombus formation, and its ED50 was 0.46 mg/kg, being 21 and 87 times as potent as aspirin and ticlopidine, respectively. These results reveal that TRK-100 has a potent antiplatelet activity and is orally and intravenously effective for a variety of thrombosis models, suggesting that it may have a therapeutic value as an antithrombotic drug.     

Pharmacological properties of the novel antimuscarinic agent 4-[2-(1,2-benzisoxazol-3-yl)-2-(hexahydro-1H-azepin-1-yl)a cetoxy]-1-et hyl-1- methylpiperidinium iodide

Pharmacological properties of 4-[2-(1, 2-benzisoxazol-3-yl)-2-(hexahydro-1H-azepin-1-yl)acetoxy]-1- ethyl-1- methylpiperidinium iodide (SX-810) were investigated and the following results were obtained. 1. In isolated guinea-pig ileum, SX-810 showed a competitive antagonistic effect against acetylcholine with a pA2 value of 7.93. 2. SX-810 (10-50 mg/kg p.o. or 10-50 micrograms/kg i.v.) inhibited the gastroduodenal contractions induced by bethanechol and carbachol in anaesthetized rats. 3. SX-810 (10-100 mg/kg p.o.) inhibited spontaneous gastric motility in conscious rats and rabbits. 4. SX-810 (10-100 mg/kg p.o.) inhibited gastric secretion in pylorus-ligated rats. 5. SX-810 (20-200 mg/kg p.o. or 1-10 mg/kg s.c.) inhibited the ulceration induced by pylorus ligation or by exposure to restrained and water-immersed stress in rats. 6. When administered orally to rats, SX-810 had no mydriatic effect even at 3000 mg/kg, but subcutaneously administered SX-810 (0.5-10 mg/kg) exhibited such action. 7. When administered orally to rats, SX-810 (100-500 mg/kg) caused no significant inhibition of the salivation induced by pilocarpine, but subcutaneously administered SX-810 (0.5-10 mg/kg) exhibited an inhibition of the salivation. In rabbits, SX-810 (200-500 mg/kg p.o.) also caused no significant inhibition of the salivation except at an extremely high dose of 1000 mg/kg p.o. 8. SX-810 (100-500 mg/kg p.o.) caused no significant effect on urine and electrolyte excretion in rats. These results indicate that oral use of SX-810 exhibits marked spasmolytic and antiulcerative activities without exerting systemic antimuscarinic side effects.     

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.     

Antiulcer effects of 3-[[[2-(3,4-dimethoxyphenyl)ethyl] carbamoyl]methyl]-amino-N-methylbenzamide in experimental gastric and duodenal ulcers

Effects of 3-[[[2-(3,4-dimethoxyphenyl)ethyl]carbamoyl] methyl]-amino-N-methylbenzamide (DQ-2511), a newly synthesized compound, were evaluated using various types of experimental gastric and duodenal ulcers in rats. Pretreatment with DQ-2511, over the dose range 30-300 mg/kg p.o., resulted in a dose-related inhibition of water-immersion stress-, serotonin-, acetylsalicylic acid (ASA)-, indometacin-, ethanol-, and 2-deoxy-D-glucose(2DG) plus indometacin-induced gastric ulcers as well as cysteamine-induced duodenal ulcers. The antiulcer potencies of DQ-2511 were equal to or greater than those of H2-receptor antagonist cimetidine in these ulcer models except for ASA- and 2DG plus indometacin-induced ulcers. The rate of healing of chronic gastric ulcers induced by acetic acid was significantly accelerated by DQ-2511 (100 and 300 mg/kg p.o.) but not by the same doses of cimetidine. DQ-2511, at doses of 30 mg/kg p.o. and above, produced a significant decrease in gastric acid and pepsin output in pylorus-ligated rats. In anesthetized rats with acute gastric fistulae, 30 mg/kg i.v. of DQ-2511 significantly inhibited gastric acid secretion stimulated by 2DG, whereas it did not affect gastric hyperacidity evoked by either carbachol, histamine or pentagastrin. At effective antiulcer doses, this compound produced a sustained increase in gastric mucosal blood flow in conscious, restrained rats. Based on these observations, DQ-2511 is characterized as a new antiulcer compound with beneficial effects on both gastric aggressive and defensive factors. Furthermore, these results indicate a possible superiority of DQ2511 over cimetidine in regard to its antiulcer potency and spectrum.     

Effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one, a new anti-ulcer agent, on experimental acute and chronic ulcers

The effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one (AG 629), a newly synthesized compound, on various experimentally induced ulcers were investigated. Oral or intraduodenal administration of AG 629 in a dose range of 25-100 mg/kg inhibited water-immersion stress ulcer, exertion ulcer, Shay ulcer, indometacin- and acetylsalicylic acid (ASA)-induced gastric ulcer, and indomethacin-induced small intestinal ulcer in rats, histamine-induced gastric ulcer in guinea pigs, and ASA-induced gastric ulcer in dogs, though it was not effective against cysteamine-induced duodenal ulcer in rats. AG 629 in doses of 6.3-25 mg/kg p.o. twice a day significantly promoted the healing of acetic acid- or thermal-cortisone-induced gastric ulcers and acetic acid-induced duodenal ulcers in rats. AG 629 (25-100 mg/kg i.d.) inhibited the secretion of gastric acid and pepsin in pylorus-ligated rats and the acid secretion stimulated by distension of the rat stomach with air, whereas this compound did not affect acid secretion stimulated by histamine, pentagastrin, carbachol or 2-deoxy-D-glucose. This study shows that AG 629 has both prophylactic and curative effects on various ulcers. The anti-ulcer effect of this agent seems to be mediated primarily by increasing mucosal resistance and secondarily by an antisecretory activity.     

Effects of elcatonin, a synthetic analogue of eel calcitonin, on acute gastric and duodenal lesions and gastroduodenal function in rats

We studied the effects of elcatonin (eel calcitonin), on various gastric and duodenal lesions, gastric acid and duodenal alkaline secretion, and gastric motility in rats. Elcatonin at 1-30 unit/kg, given subcutaneously, dose-dependently inhibited the development of HCl-aspirin-, HCl-ethanol-, water-immersion stress- and indomethacin-induced gastric lesions. This agent also significantly prevented the formation of duodenal lesions induced by indomethacin plus histamine at 30 unit/kg, although it showed only a tendency of inhibition against mepirizole-induced duodenal lesions. 16, 16-Dimethyl prostaglandin E2 (3-30 micrograms/kg), given orally as a reference drug, showed a potent inhibition against all types of lesions tested herein at the dose of 3 micrograms/kg or greater. Elcatonin dose-dependently inhibited gastric secretion (volume, acid and pepsin output) in pylorus-ligated rats and gastric motility in conscious rats, but had no effect on duodenal alkaline secretion in anesthetized rats. On the other hand, 16, 16-dimethyl prostaglandin E2 at 10 micrograms/kg, given intraduodenally, significantly inhibited gastric secretion and motility, but stimulated duodenal alkaline secretion. We conclude that elcatonin markedly protects the gastrointestinal mucosa from injury induced by stress or various irritants. These effects might be in part accounted for by the antisecretory and antimotility activities of this peptide, although some other unknown mechanisms may be involved in the mucosal protection afforded by elcatonin.     

Effects of indomethacin on the duodenal mucosa of rats: comparative study with cysteamine

Effects of indomethacin and cysteamine on the duodenal mucosa of rats were studied microscopically (using scanning electron microscopy) and also functionally. Indomethacin (5 mg/kg, s.c.) induced no microscopic damage to the duodenal epithelium for up to 6 hr after administration. Indomethacin had no effects on gastric H+ output and the amount of H+ in the duodenum, but did reduce the duodenal HCO3- secretion (both basal and 10 mM-HCl stimulated). PGE2 contents in the duodenal mucosa were markedly reduced by indomethacin for 6 hr. These results suggest that reductions of duodenal HCO3- secretion and endogenous prostaglandins per se do not impair the H+ disposal system of the duodenum and so do not damage the epithelial cells. In contrast, cysteamine (100 mg/kg, s.c.) produced microscopic damage to the duodenal epithelium as early as 2 hr later. Cysteamine significantly increased gastric H+ output and reduced duodenal HCO3- secretion, resulting in an increased amount of H+ in the duodenum 3 hr later. Cysteamine had no effect on PGE2 contents in the duodenum. The time lag between damage formation and functional changes suggests that the earliest damage caused by cysteamine occurs by mechanisms other than erosive action of H+ emptied by the stomach. The increased amount of H+ may contribute to an enhancement of the initial damage.