Effect of cimetidine and omeprazole on gastric ulcer healing of rats with limited food intake time

Influence of aging on gastric ulcer healing activities of the antioxidants alpha-tocopherol and probucol

In the present study, we compared the effects of alpha-tocopherol and probucol, antioxidants, on the healing of acetic acid-induced gastric ulcers in 8-, 48- and 96-week-old rats. The repeated oral administration of alpha-tocopherol (16 mg/kg twice daily) and probucol (1000 mg/kg twice daily) for 14 consecutive days markedly accelerated the gastric ulcer healing in 48- and 96-week-old rats as well as 8-week-old ones. The ulcer healing effects of both drugs were not significantly different among the rats at three different ages. The superoxide dismutase (SOD) activity in the ulcerated region of 8-, 48- and 96-week-old rats was markedly lower than that in the unulcerated region. In contrast, the thiobarbituric acid (TBA)-reactive substance content, an index of lipid peroxidation, in the ulcerated region of rats at three different ages markedly increased, as compared to that in the unulcerated region. The SOD activity tended to decrease with aging, while the TBA-reactive substance content gradually increased. The repeated administration of alpha-tocopherol and probucol accelerated the ulcer healing and inhibited the increase in the TBA-reactive substance content in the ulcerated region. These results suggest that alpha-tocopherol and probucol promote the ulcer healing by their potent antioxidant activities in 48- and 96-week-old rats as well as 8-week-old rats.

The antiulcer effect of Croton cajucara Benth in normoproteic and malnourished rats

The aim of the present study is to investigate the antiulcerogenic effects of the essential oil (EO) of Croton cajucara Benth in rats fed with a normal protein (NP) and low-protein diet (MN). NP and MN rats were treated with the essential oil for 15 days after chronic ulceration was induced. The EO accelerated healing of acetic acid-induced gastric lesions in NP and MN rats (p<0.05). In a similar experiment on chronic ulceration, Epidermal Growth Factor (EGF) mRNA expression increased in NP rats but not in MN rats. In assays of acute antiulcerogenic activity, C. cajucara increased somatostatin plasma levels and decreased gastrin plasma levels in both animal groups. The EO significantly prevented ethanol-induced gastric ulcers in NP and MN rats (p<0.001). Histological examination showed initial regeneration, formation of inflammatory infiltrate and angiogenesis in the epithelium surface of acetic acid-induced ulcers in NP and MN rats. C. cajucara prevented gastric lesions in both animal groups when ethanol methodology was used. We concluded that the EO showed an antiulcerogenic activity mediated by increased somatostatin secretion and EGF mRNA expression.

A vascular endothelial growth factor mimetic accelerates gastric ulcer healing in an iNOS-dependent manner

Angiogenesis is crucial to all types of wound healing, including gastric ulcer healing. The most potent promoter of angiogenesis is vascular endothelial growth factor (VEGF). We hypothesized that a 15-amino acid peptide designed to mimic the angiogenic action of VEGF would accelerate gastric ulcer healing. Gastric ulcers were induced in mice by serosal application of acetic acid. Treatment with the VEGF mimetic accelerated gastric ulcer healing when administered orally or intraperitoneally, at a dose of 50 ng/kg or greater. Such healing was not observed when the reverse sequence pentadecapeptide or the full-length VEGF protein was administered. Contrary to our hypothesis, the VEGF mimetic did not significantly increase angiogenesis in the ulcerated stomach. The enhancement of ulcer healing by the VEGF mimetic occurred independently of cyclooxygenase-2 (COX-2) activity but was blocked by inhibitors of inducible nitric oxide synthase (iNOS). These results demonstrate that a VEGF mimetic is a potent stimulus for gastric ulcer healing, even when given orally. The effects of the mimetic were independent of stimulatory effects on angiogenesis and COX-2 activity but were dependent on iNOS-derived NO production.

Anti-ulcer effect of tea catechin in rats

Oral administration of tea catechin dose-dependently prevented absolute ethanol-induced (50, 100, 200 mg/kg) or restraint plus water immersion stress-induced acute gastric mucosal injury (300, 400 mg/kg) in rats. When the effect of test compound was evaluated on the 15th day after acetic acid injection to rats, repeated oral administration of tea catechin (25, 50, 100 mg/kg twice daily) dose-dependently accelerated the healing of acetic acid-induced chronic gastric ulcers. Tea catechin (10(-5)-10(-1) g/100 ml) concentration-dependently scavenged superoxide anions in vitro. Tea catechin (100, 200 mg/kg orally) markedly inhibited the increase in thiobarbituric acid-reactive substances in the injured mucosa of rats treated with 50% ethanol. Tea catechin (50, 100 mg/kg twice orally, daily) markedly inhibited the increase in content of thiobarbituric acid-reactive substances in the ulcerated region of acetic acid-induced gastric ulcers on the 7th and 15th days. In addition, at 50, 100 and 200 mg/kg orally, it dose-dependently prevented the decrease in gastric mucosal hexosamine content induced by absolute ethanol, although it failed to inhibit the basal gastric acid secretion. These results suggest that tea catechin may primarily protect gastric mucosa from acute gastric mucosal injury and promote the healing of chronic gastric ulcers by its antioxidant activity and gastric mucus-increasing actions.

Ganoderma lucidum polysaccharide fractions accelerate healing of acetic acid-induced ulcers in rats

The polysaccharide (PS) fractions from several medicinal herbs have been reported to have anti-ulcer effects against experimental ulcers in the rat. The water-soluble PS fractions from Ganoderma lucidum (Reishi mushroom) have been shown to inhibit indomethacin-induced gastric mucosal lesions in rats. This study aimed to investigate the effect of the PS fraction from G. lucidum on the healing of gastric ulcers induced by acetic acid in the rat and to elucidate the underlying mechanisms involved. The abdomen of rats was incised, and the stomach was treated with 10 M acetic acid (100 microL) for 1 minute, and then treated with G. lucidum PS (0.1, 0.5, or 1.0 g/kg) intragastrically, once a day for 14 consecutive days. The results indicated that the oral administration of G. lucidum PS at 0.5 and 1.0 g/kg for 2 weeks caused a significant acceleration of ulcer healing by 40.1% and 55.9%, respectively. In the mechanistic studies, additional rats were treated with 10 M acetic acid to induce acute ulcers, and then treated with G. lucidum PS (1.0 g/kg) for 3, 7, 10, or 14 days. Exposure of the rat stomach to acetic acid led to decreased mucus and increased prostaglandin levels. Treatment with G. lucidum PS at 1.0 g/kg significantly (P < .05) suppressed or restored the decreased gastric mucus levels and increased gastric prostaglandin concentrations compared with the control group. These results indicates that G. lucidum PS is an active component with healing efficacy on acetic acid-induced ulcers in the rat, which may represent a useful herbal preparation for the prevention and treatment of peptic ulcers.

The protective effect of vitamin C, vitamin E and selenium combination therapy on ethanol-induced duodenal mucosal injury

In this study, the effect of a combination of vitamin C, vitamin E and selenium on ethanol-induced duodenal mucosal damage in rats was investigated morphologically and biochemically. The duodenal mucosal injury was produced by oral administration of 1 mL of absolute ethanol to each rat. Animals received vitamin C (250 mg/ kg), vitamin E (250 mg/kg) and selenium (0.5 mg/kg) for 3 days and absolute ethanol 1 hour after last antioxidant administration and were sacrificed 1 hour after absolute ethanol. Extreme degeneration in intestinal mucosa of rats given ethanol was observed morphologically. In addition, an increase in neuronal nitric oxide synthase immunoreactive areas was observed in the rats of the group given ethanol. On the other hand, a normal morphological appearance and a decrease in neuronal nitric oxide synthase immunoreactive areas were detected in the rats given ethanol+vitamin C+vitamin E+ selenium. In the group to which ethanol was administered, an increase in serum cholesterol and a decrease in serum albumin levels were determined. On the other hand, in the group to which ethanol+vitamin C+vitamin E+selenium were administered, serum cholesterol value decreased, and the serum albumin level increased. As a result, we can say that the combination of vitamin C, vitamin E and selenium has a protective effect on ethanol-induced duodenal mucosal injury.

Acceleration of gastric ulcer healing by omeprazole in portal hypertensive rats. Is its action mediated by gastrin release and the stimulation of epithelial proliferation?

BACKGROUND

Gastric ulcer healing is delayed in patients with portal hypertension (PHT) and often responds poorly to histamine H(2) blockers. Although proton pump inhibitors are more effective anti-ulcer agents, there is little information regarding their efficacy for gastric ulcer in cases of PHT. Therefore, we investigated the effects of a proton pump inhibitor, omeprazole, on the healing of acetic-acid-induced gastric ulcer in PHT rats.

METHODS

Animals studied were 80 male Sprague-Dawley rats aged 7 weeks, of which half underwent two-staged portal vein ligation (PHT rats) and half underwent a sham operation (SO rats). Gastric ulcers were induced by acetic acid. Starting from day 4 after ulcer induction, rats received omeprazole or vehicle orally (50 mg/kg) for 5 or 10 days. Ulcer area, proliferating cell nuclear antigen labelling index (PCNA LI), and serum gastrin levels were recorded.

RESULTS

PHT significantly inhibited epithelial cell proliferation and delayed gastric ulcer healing as indicated by a decreased PCNA LI at the ulcer margin and almost 2-fold larger ulcer area in PHT versus SO rats 14 days after ulcer induction. Ten-day treatment with omeprazole (vs. vehicle) significantly accelerated ulcer healing to a similar extent in both PHT and SO rats. Serum gastrin levels were significantly higher in PHT rats than in SO rats following treatment with omeprazole. Omeprazole (vs. vehicle) restored the decreased PCNA LI at the ulcer margin in PHT rats to that noted in SO rats.

CONCLUSIONS

In PHT rats, omeprazole accelerates gastric ulcer healing, stimulates epithelial cell proliferation at the ulcer margin, and increases serum gastrin levels. Since gastrin is a potent stimulator of gastric epithelial cell proliferation, increased serum gastrin levels may be an important factor in omeprazole-induced stimulation of epithelial cell proliferation and acceleration of gastric ulcer healing in conditions of PHT.

The acetone soluble fraction from bark extract of Stryphnodendron adstringens (Mart.) coville inhibits gastric acid secretion and experimental gastric ulceration in rats

The acetone soluble fraction from a crude methanol extract of Stryphnodendron adstringens stem bark (AFSAB) was evaluated in acute (ethanol, indomethacin and hypothermic restraint-stress) and chronic (acetic acid) models of gastric ulceration and on basal and bethanechol-stimulated gastric acid secretion in rats. Rats pretreated orally with AFSAB at doses of 400 and 800 mg/kg showed significant decreases of gastric lesion scores in ethanol (62% and 98%) and hypothermic restraint-stress (89% and 88%) models but exerted no significant influence on indomethacin-induced acute or acetic acid-induced chronic ulceration. In pylorus-ligated rats, AFSAB significantly decreased the basal as well as bethanechol-stimulated gastric secretory volume and the total acidity with an elevated pH value. AFSAB failed to modify the gastric mucus and the gastric wall nonprotein-sulphydryl content. These results point to a possible antisecretory effect of AFSAB which account for the observed antiulcer activity in ethanol and hypothermic restraint-stress induced models of acute gastric ulceration.

Influence of aging on gastric ulcer healing activities of cimetidine and omeprazole

In this study, we compared the effects of cimetidine and omeprazole on the healing of acetic acid-induced gastric ulcers in 8-, 48-, and 96-week-old rats. The repeated oral administration of cimetidine or omeprazole for 14 consecutive days markedly accelerated the ulcer healing in 8- and 48-week-old rats. However, both drugs were ineffective in 96-week-old rats. The basal gastric acid secretion of 8-, 48-, and 96-week-old rats decreased with aging. A single oral administration of cimetidine or omeprazole strongly decreased basal gastric acid secretion in the three different ages of rats. Cimetidine and omeprazole produced a potent and sustained serum gastrin-elevating action in 8- and 48-week-old rats. However, the gastrin-elevating actions of both drugs in 96-week-old rats were much weaker than in the 8- and 48-week-old rats. These results indicate that cimetidine and omeprazole have potent gastric ulcer healing actions in 8- and 48-week-old rats, as well as potent serum gastrin-elevating actions, but both drugs are ineffective in 96-week-old rats, which have lost their gastrin-elevating actions.

Effect of the antiulcer polysaccharide fraction from Bupleurum falcatum L. on the healing of gastric ulcer induced by acetic acid in rats

An antiulcer polysaccharide fraction (BR-2) from Bupleurum falcatum L. was examined for its effect on the healing of chronic ulcers induced by acetic acid in rats. When BR-2 was administered orally to the rats, it was shown to be effective in the healing of acetic acid-induced chronic ulcer. This result suggests that the use of herbal prescriptions containing B. falcatum L. may prove useful for the treatment of peptic ulcers.

Involvement of gastrin in gastric secretory and protective actions of N-alpha-methyl histamine

N alpha-methylhistamine (N alpha-MH) is one of an unusual metabolite of histamine that was found in Helicobacter pylori-infected stomachs and is believed to interact with specific histamine H(1), H(2) and H(3)-receptors to stimulate gastric acid secretion and gastrin release from isolated G-cells but the effects of N alpha-MH on gastric mucosal integrity have been little studied. This study was designed; (1) to compare the effect of exogenous N alpha-MH with that of standard histamine on gastric secretion and plasma gastrin levels in rats equipped with gastric fistula (series A); and (2) to assess the action of N alpha-MH on gastric lesions induced by 100% ethanol (series B) in rats with or without removal of antral portion of the stomach (antrectomy). Rats of series B were pretreated intragastrically (i.g.) or intraperitoneally (i.p.) with N alpha-MH or histamine (0.1-2 mg/kg) 30 min prior to 100% ethanol (1.5 ml, i.g.) with or without: (1) vehicle (saline); (2) RPR 102681 (30 mg/kg i.p.), to block CCK-B/gastrin receptors; and (3) ranitidine (40 mg/kg s.c.) to inhibit histamine H(2)-receptors. The area of gastric lesions was determined planimetrically, gastric blood flow (GBF) was assessed by H(2)-gas clearance method and venous blood was collected for determination of plasma gastrin levels by radioimmunoassay (RIA). N alpha-MH and histamine dose-dependently increased gastric acid output (series A); the dose increasing this secretion by 50% (ED(50)) being 2 and 5 mg/kg i.g or i.p., respectively, and this effect was accompanied by a significant rise in plasma gastrin levels. Both, N alpha-MH and histamine attenuated dose-dependently the area of gastric lesions induced by 100% ethanol (series B) while producing significant rise in the GBF and plasma immunoreactive gastrin increments. These secretory, protective, hipergastrinemic and hyperemic effects of N alpha-MH and histamine were completely abolished by antrectomy, whereas pretreatment with RPR 102681 attenuated significantly the N alpha-MH and histamine-induced protection against ethanol damage and accompanying hyperemia. Ranitidine, that produced achlorhydria and a further increase in plasma gastrin levels, failed to influence the N alpha-MH- and histamine-induced protection and accompanying rise in the GBF. We conclude that (1) N alpha-MH stimulates gastric acid secretion and exhibit gastroprotective activity against acid-independent noxious agents in the manner similar to that afforded by histamine; and (2) this protection involves an enhancement in the gastric microcirculation and release of gastrin acting via specific CCK-B/gastrin receptors but unexpectedly, appears to be unrelated to histamine H(2)-receptors.

Anti-ulcer effects of chitin and chitosan, healthy foods, in rats

In this study, we compared the effects of low molecular weight (LMW) chitosan (MW: 25,000-50,000), high molecular weight (HMW) chitosan (MW: 500,000-1000,000) and chitin on ethanol-induced gastric mucosal injury and on the healing of acetic acid-induced gastric ulcers in rats. Oral administration of LMW chitosan (250, 500 and 1000 mg/kg) dose-dependently prevented ethanol-induced gastric mucosal injury. Repeated oral administration of LMW chitosan (100, 200 and 400 mg/kg twice daily) also dose-dependently accelerated the gastric ulcer healing. However, the effects of HMW chitosan and chitin on the gastric mucosal injury formation and the gastric ulcer healing were less potent than those of LMW chitosan. LMW chitosan (250 and 500 mg/kg, orally) was ineffective in inhibiting gastric acid secretion in pylorus-ligated rats, although it had a weak acid-neutralizing action. LMW-chitosan (250, 500 and 1000 mg/kg orally) dose-dependently prevented the decrease in gastric mucus content induced by ethanol. These results indicate that of the three compounds, LMW chitosan has the most potent gastric cytoprotective and ulcer healing-promoting actions. In addition, gastric mucus-increasing action of LMW-chitosan may be, at least in part, related to the anti-ulcer effect of this compound.

Anti-ulcer effects of antioxidants, quercetin, alpha-tocopherol, nifedipine and tetracycline in rats

When free radical-scavenging activities of quercetin, alpha-tocopherol, nifedipine and tetracycline were measured by an electron spin resonance technique, all test compounds (10(-5) to 10(-3) M) scavenged both superoxide anions and hydroxyl radicals. The oral administration of quercetin (50 and 100 mg/kg), alpha-tocopherol (8 and 16 mg/kg), nifedipine (20 and 40 mg/kg) or tetracycline (10 and 20 mg/kg) markedly prevented the HCl plus ethanol-induced gastric mucosal injury and the increase in the content of thiobarbituric acid-reactive substances in the injured mucosa in rats. In addition, quercetin (25, 50 and 100 mg/kg), alpha-tocopherol (4, 8 and 16 mg/kg), nifedipine (10, 20 and 40 mg/kg) and tetracycline (5, 10 and 20 mg/kg), given orally, twice daily for 14 consecutive days from the day after acetic acid injection, dose-dependently promoted the ulcer healing and inhibited the increase in the content of thiobarbituric acid-reactive substances in the ulcerated mucosa. These results indicate that quercetin, alpha-tocopherol, nifedipine and tetracycline possess gastric cytoprotective and gastric ulcer healing-promoting actions. In addition, the free radical-scavenging properties of these compounds may be partly related to their anti-ulcer effects.

Anti-ulcer effects of antioxidants: effect of probucol

We investigated the effect of probucol, a lipid-lowering agent with antioxidant properties, on HCl plus ethanol-induced gastric mucosal injury and on the healing of acetic acid-induced gastric ulcers in rats. When the free radical-scavenging activity of probucol was measured by an electron spin resonance technique, the agent (10(-5)-10(-3) M) scavenged both superoxide anions and hydroxyl radicals. Oral administration of probucol (250-1000 mg/kg) dose dependently prevented the HCl plus ethanol-induced gastric mucosal injury and the increase in thiobarbituric acid-reactive substances, an index of lipid peroxidation, in the injured mucosa. Repeated oral administration of probucol (250-1000 mg/kg twice daily) dose dependently accelerated the healing of acetic acid-induced gastric ulcers. In addition, probucol already inhibited the increase in the content of thiobarbituric acid-reactive substances in the ulcerated region before the ulcer-healing effect of this agent was recognized. These results suggest that probucol may partly protect gastric mucosa from acute gastric mucosal injury and promote the healing of chronic gastric ulcers by its antioxidant activity.

Healing-promoting action of the zinc-cimetidine complex on acetic acid-induced gastric ulcers in rats

We investigated the effect of the zinc-cimetidine complex on the healing of acetic acid-induced gastric ulcers in rats. When the effects of test drugs were assessed on the 15th day after acetic acid injection, the zinc-cimetidine complex at oral doses of 15.0 (11.4 mg as cimetidine), 30.0 and 60.0 mg/kg twice daily promoted the ulcer healing in a dose-dependent manner. Cimetidine was effective at oral doses of over 45.4 mg/kg twice daily. ZnCl2 was ineffective on all ulcer parameters. The effect of the combination of cimetidine and ZnCl2 was similar to that of cimetidine alone. The zinc-cimetidine complex had already inhibited the increase in thiobarbituric acid reactants in the ulcerated region before the ulcer-healing effect of this compound was recognized. A single oral administration of the complex at 15 and 30 mg/kg to normal rats was ineffective in inhibiting acid secretion and in increasing serum gastrin levels, although cimetidine was markedly effective on both parameters. These results indicate that the zinc-cimetidine complex at about 1/4 the dose of cimetidine was as effective as cimetidine when the ulcer-healing effects of both compounds were compared with the same dose of cimetidine. In addition, the ulcer-healing effect of this complex may be due, at least in part, to the inhibition of lipid peroxidation but not due to the inhibition of acid secretion or the trophic effect of gastrin.

Cimetidine and omeprazole accelerate gastric ulcer healing by an increase in gastrin secretion

Daily oral administration of cimetidine or omeprazole markedly accelerated the healing of acetic acid-induced gastric ulcers in rats with a limited food intake time. The increased gastric acid secretion induced by daily treatment with histamine affected neither the spontaneous healing of the ulcers nor the healing-promoting actions of both agents. Pretreatment of rats with ulcers with 6-hydroxydopamine significantly inhibited the increase in the antrum gastrin cells, serum gastrin levels and corpus mucosal thickness elicited by repeated administration of cimetidine or omeprazole. Pretreatment with 6-hydroxydopamine did not affect the inhibitory actions of cimetidine and omeprazole on acid secretion, but completely abolished the ulcer healing-promoting actions of both drugs. Daily intraperitoneal administration of pentagastrin accelerated ulcer healing. These results suggest that cimetidine and omeprazole mainly accelerate the healing of gastric ulcers by the trophic action of gastrin via the increase in gastrin secretion, while the inhibition of acid secretion may play a minor role in ulcer healing.