Healing Of Experimental Gastric Ulcers Research Articles

Growth Factors in Benign Gastrointestinal Diseases

Mucosal ulceration in the gastrointestinal tract leads to the development of a novel cell lineage which locally secretes growth factors such as trefoil peptides and epidermal growth factor (EGF). Gastric mucosal ulceration causes an increase of EGF receptor density and a profound decrease of somatostatin receptor density in the mucosal ulcer margin and scar. These changes in growth factors and their receptors cause a strong increase of cell proliferation in the ulcer margin. In experimental ulcer models, EGF and basic fibroblast growth factor (bFGF) promote ulcer healing by increasing epithelial cell proliferation and angiogenesis, respectively. Indomethacin delays ulcer healing by decreasing epithelial cell proliferation, inhibition of angiogenesis, and inhibition of remodelling of the granulation tissue in the ulcer base. Indomethacin interferes with EGF binding and proliferative response of gastric cultured KATO III cells. In addition, bFGF cannot reverse indomethacin-induced deleterious effects on experimental gastric ulcer healing. In summary, growth factors play an important role in promoting wound healing in benign gastrointestinal diseases.

Influence of capsaicin-sensitive afferent fibers on acetic acid-induced chronic gastric ulcers in rats.

Accumulating evidence indicates that capsaicin-sensitive afferent fibers play a pivotal role in acute gastroprotection. However, whether they also influence healing of chronic gastric ulcers is still unknown. The effects of ablation of sensory neurons on acetic acid-induced chronic gastric ulcers in rats were investigated at morphologic and biochemical levels by computerized imaging analysis of the ulcerated area, histologic examination, and neuropeptide determination. Afferent nerve ablation, as a result of treating rats with a neurotoxic dose of capsaicin (50 + 50 mg/kg subcutaneously over 2 days), produced a significant increase in the ulcer area at 1 and 2 weeks after acetic acid injection. The delay in ulcer healing was associated with a marked and persistent decrease in tissue calcitonin gene-related peptide-like immunoreactivity, whereas gastric vasoactive intestinal polypeptide was unaffected by capsaicin pretreatment. Histologically, as compared with control rats, capsaicin-desensitized animals only differed in a slight increase in the inflammatory infiltrate during the early phase of ulcer formation. These findings suggest that capsaicin-sensitive afferent fibers may play a role in the healing of chronic experimental gastric ulcers in rats, but the underlying mechanisms remain to be elucidated and deserve further investigation.

Helicobacter pylori affects the quality of experimental gastric ulcer healing in a new animal model

Helicobacter pylori has been implicated in the genesis of human gastritis, dyspepsia, and peptic ulcers. However, its influence in the quality of experimental gastric ulcer healing has not been previously investigated. Standardized gastric fundic ulcers were produced in 50 male Sprague-Dawley rats (150–200 g) by a 4 mm in diameter focal, serosal application of 100% acetic acid. Thirty rats were administered 2 ml H. pylori suspension (urease producing, ATCC 43504) in normal saline (10 8 CFU/ml) 2×/day for 7 days. Twenty rats (controls) received 2 ml normal saline 2×/day for 7 days. Gastric ulcer surface area was measured under a dissecting microscope and mucosal specimens were obtained for qualitative and quantitative histology. No gross or microscopic duodenal abnormalities were identified at sacrifice. Ninety percent of control rats showed grossly and microscopically entirely healed ulcers. The remaining 10% showed partially reepithelialized ulcers (area, 0.78 to 1.77 mm 2; mean, 1.27 ± 0.7 mm 2). The grossly “healed” mucosa demonstrated marked dilatation of gastric glands lined with mature surface epithelial cells. Parietal cells were scanty (5–10% of all cells). One hundred percent of the H. pylori-exposed rats showed persistence of chronic active ulcers (area, 1.76 to 19.63 mm 2; mean, 8.95 ± 6.15 mm 2). The ulcer beds were infiltrated by acute and chronic inflammatory cells, abundant fibroblasts, and capillary networks. The raised ulcer borders were characterized by dilated glands lined by mature surface epithelial cells. Various special stains demonstrated the presence of H. pylori in the surface mucus and within the crypts. We conclude that (1) H. pylori delays healing of experimental gastric ulcers distorting the restoration of mucosal architecture and (2) this animal model is extremely useful for the study of the role of H. pylori in the healing of experimental peptic ulcers.

Effects of Prostaglandins on Hydrocortisone-Induced Delayed Healing of Chronic Gastric Ulcers in the Rat

We have previously shown that chronic steroid administration delays the healing of experimental gastric ulcers in rats. This study was designed to test the beneficial effects of 16,16-dimethylprostaglandin E2 or TRY-200, a stable prostaglandin I2 analogue, on the delayed healing by hydrocortisone (HC) of chronic gastric ulcers in rats. Chronic gastric ulcers were produced in male Wistar rats, weighing 180 g, by serosal application of 100% acetic acid. The rats were randomly divided into six groups: (1) saline, (2) saline, HC-treated, (3) 10 micrograms/kg of 16,16-dimethylprostaglandin E2, (4) TRY-200, a stable prostaglandin I2 analogue, at 5 micrograms/kg, or (5) 10 micrograms/kg, or (6) 30 micrograms/kg. All rats, except for control, were given daily intraperitoneal injection of 2.5 mg/kg of HC sodium phosphate. Tested drugs were administered intragastrically twice a day for 2 weeks. Rats were killed 14 days later and ulcer size was measured. Chronic administration of HC sodium phosphate resulted in a significant delay of ulcer healing induced by acetic acid. Treatment with TRY-200 at 10 or 30 micrograms/kg abolished the deleterious effect of steroids, whereas 16,16-dimethylprostaglandin E2 had no effect. These results indicate that prostaglandin I2 is more effective than prostaglandin E2 in reversing the delayed healing by steroids of chronic gastric ulcers in the rat.

Effects of sucralfate, lansoprazole, and cimetidine on the delayed healing by hydrocortisone sodium phosphate of chronic gastric ulcers in the rat

We have previously shown that chronic sucralfate ingestion stimulates gastric epithelial proliferation in rats, which may explain one of the beneficial effects of sucralfate in healing of peptic ulcers. In a separate study, we have found that chronic steroid administration delays the healing of experimental gastric ulcers in rats. This study was designed to test the beneficial effects of sucralfate, cimetidine, and lansoprazole (AG-1749, a new proton pump inhibitor), on the delayed healing by steroids in rat chronic gastric ulcers. Chronic gastric ulcers were produced in male Wistar rats, weighing 180 g, by the application of 100% acetic acid. The rats were randomly divided into five groups; (1) control, (2) vehicle alone, (3) 10 mg/kg lansoprazole, (4) 500 mg/kg sucralfate, and (5) 100 mg/kg cimetidine. Except for controls, all rats received daily intraperitoneal injections of 2.5 mg/kg hydrocortisone sodium phosphate. Tested drugs were administered intragastrically (lansoprazole and sucralfate) or intraperitoneally (cimetidine) twice a day for 2 weeks. Rats were sacrificed 14 days later and ulcer size was measured. Chronic administration of hydrocortisone sodium phosphate resulted in a significant delay of ulcer healing induced by acetic acid. Treatment with either lansoprazole or sucralfate abolished the deleterious effect of steroids, whereas cimetidine had no effect. These results indicate that lansoprazole and sucralfate overcome the delayed healing by steroids of chronic gastric ulcers in the rat.

Effect of Indomethacin on Gastric Mucosal Blood Flow Around Acetic Acid-Induced Gastric Ulcers in Rats

Repeated administration of indomethacin markedly delays spontaneous healing of experimental gastric ulcers induced in rats. To elucidate the underlying mechanism, the effect of indomethacin on the gastric mucosal blood flow around ulcers was examined. Gastric ulcers were induced 5 days after submucosal injection of an acetic acid solution into the stomachs of rats. Blood flow was determined by the hydrogen gas clearance method. The blood flow around ulcers was significantly higher than that in rats without ulcers up to 2 weeks after ulceration but had returned to within the normal range 3 or 4 weeks later. Indomethacin, administered SC at 1 mg/kg once or repeatedly for 1-4 weeks, had little or no effect on the blood flow in normal rats. However, such treatment significantly reduced the blood flow by 20%-30% of the corresponding control levels in rats with ulcers. Prostaglandin E2, administered SC at 3 mg/kg once, markedly prevented the reduction in the blood flow due to indomethacin. The administration of prostaglandin E2, with indomethacin for 4 weeks resulted in a significantly higher blood-flow level than the control and prevented the delay in ulcer healing. Omeprazole, administered SC at 30 mg/kg once or repeatedly with indomethacin for 4 weeks, had an insignificant effect on the blood flow around ulcers but prevented the delay in ulcer healing. In conclusion, the delayed ulcer healing caused by indomethacin might be partly related to the reduced blood flow around the ulcers.

Effect of indomethacin on gastric mucosal blood flow around acetic acid-induced gastric ulcers in rats

Repeated administration of indomethacin markedly delays spontaneous healing of experimental gastric ulcers induced in rats. To elucidate the underlying mechanism, the effect of indomethacin on the gastric mucosal blood flow around ulcers was examined. Gastric ulcers were induced 5 days after submucosal injection of an acetic acid solution into the stomachs of rats. Blood flow was determined by the hydrogen gas clearance method. The blood flow around ulcers was significantly higher than that in rats without ulcers up to 2 weeks after ulceration but had returned to within the normal range 3 or 4 weeks later. Indomethacin, administered SC at 1 mg/kg once or repeatedly for 1–4 weeks, had little or no effect on the blood flow in normal rats. However, such treatment significantly reduced the blood flow by 20%–30% of the corresponding control levels in rats with ulcers. Prostaglandin E2, administered SC at 3 mg/kg once, markedly prevented the reduction in the blood flow due to indomethacin. The administration of prostaglandin E2, with indomethacin for 4 weeks resulted in a significantly higher blood-flow level than the control and prevented the delay in ulcer healing. Omeprazole, administered SC at 30 mg/kg once or repeatedly with indomethacin for 4 weeks, had an insignificant effect on the blood flow around ulcers but prevented the delay in ulcer healing. In conclusion, the delayed ulcer healing caused by indomethacin might be partly related to the reduced blood flow around the ulcers.

Inflammation, capillary leakage and healing of experimental gastric ulcers in the rat.

Little information is available on the role of inflammation and small vessel alteration in the development and healing of peptic ulcers. We studied the spontaneous healing of experimental ulcers in the rat stomach with a novel radio-isotope technique for the monitoring of capillary damage in ulcer-related inflammation. Following ulcer induction, healing was assessed on days 1, 7 and 15 by macroscopical and histological determinations of ulcer size and lesion area, parietal cell counts in the ulcer margin and nuclear imaging of the lesion area using Nanocoll, a 99mTc-labelled colloid. The ulcers were re-epithelized after 15 days. However, Nonocoll activity was still significantly enhanced in the ulcer area, and regression of the microscopically visible lesion area, which, from day 1 on, occupied a zone considerably larger than the ulcer itself, was delayed and still incomplete at the end of the study. Compared to the intact mucosa, parietal cells were reduced in the scar tissue up to 15 days (24-40%). However, despite macroscopical and histological re-epithelization, small vessel leakage and substantial tissue alteration persisted in the ulcer scar.

Effect of Epidermal Growth Factor in Combination with Sucralfate or Omeprazole on the Healing of Chronic Gastric Ulcers in the Rat

Epidermal growth factor (EGF) has been shown to enhance healing of experimental gastric ulcers when given subcutaneously or orally in the drinking water. This effect of EGF occurs without reducing gastric acid secretion. On the other hand, EGF reportedly is excreted rapidly from gastric lumen when administered by intragastric bolus. This suggests that further stimulation of ulcer healing may be expected if EGF is given with an acid-suppressive agent or with an agent allowing EGF to remain in rat gastric lumen at high concentrations. In the present study, EGF administered by gastric intubation at a dose of 10 micrograms/kg, which is three times smaller than reported in previous studies, was evaluated for its effect on acetic acid-induced rat gastric ulcers in combination with sucralfate or omeprazole. Sucralfate is well known selectively to bind proteins covering the ulcer base, and omeprazole is a potent acid-suppressive agent. Prior to the study of combined EGF and sucralfate, oral sucralfate was confirmed to allow endogenous gastric EGF and mouse EGF given exogenously to remain at high concentrations in gastric contents and tissues. EGF and sucralfate (2 g/kg/day) given alone failed to stimulate ulcer healing in submandibularectomized rats (SMR rat) whose endogenous gastric EGF was depleted. However, the combination of both drugs administered at the same doses significantly accelerated ulcer healing in the SMR rat. Omeprazole (200 mg/kg/day) significantly enhanced ulcer healing regardless of removal of the submandibular glands. The combination of EGF and omeprazole further stimulated ulcer healing in the SMR rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Indomethacin, Prostaglandins and Omeprazole on Healing of Experimental Gastric Ulcers

Prostaglandins and indomethacin exert trophic effects on the gastric mucosa which could be advantageous to ulcer healing. To examine the possibility of such a role, the effects of high and low doses of prostaglandin, indomethacin and omeprazole were compared in an experimental ulcer model. Gastric ulcers were induced in rats by a crypoprobe. This was followed by 5 to 10 days’ treatment with 16,16-dimethyl dinoprostone (prostaglandin E2) [5 or 100 μg/kg twice daily, intragastrically], omeprazole (40 μmol/kg once daily, subcutaneously), indomethacin (2 mg/kg twice daily, subcutaneously) or placebo. At the end of treatment, plasma gastrin levels, the size and depth of the ulcer and the labelling index in the area neighbouring the ulcer were measured. Omeprazole accelerated ulcer healing, as indicated by a smaller ulcer area and depth after 10 days’ treatment. Prostaglandins did not affect ulcer healing despite an increase in the height of the mucosa adjacent to the ulcer. Indomethacin delayed ulcer healing and reduced the labelling index of ulcer-adjacent mucosa. These observations suggest that the trophic and ‘cytoprotective’ effects of prostaglandins are not relevant for ulcer healing in this model. This is not unexpected, since the trophic effect induced by prostaglandins mainly results from an increase in the life cycle of the superficial mucus-producing cells and not by the enhancement of cell reproduction.

Effects of NC-1300, a gastric proton pump inhibitor, on healing of acetic acid-induced gastric ulcers in rats.

Effects of NC-1300 (a gastric proton pump inhibitor) on healing of experimental chronic gastric ulcers induced in rats were studied. Gastric ulcers were induced by the submucosal injection of 20% acetic acid (0.03 ml) into the antral-oxyntic border of the anterior wall of male Donryu rats (260-280 g). The healing of acetic acid ulcers was delayed by the daily subcutaneous administration of indomethacin (1 mg/kg) for two or four weeks after ulceration. Aggravation of healed ulcers was evoked by subcutaneous administration of indomethacin (1 mg/kg) once daily for four weeks to rats with four-week-old ulcers. Oral administration of NC-1300 (10, 30, or 100 mg/kg) once daily for two or four weeks after ulceration dose-dependently accelerated both natural and delayed healing of acetic acid ulcers. When the period of administration was extended from two to four weeks, the ED50 values (the dose reducing the ulcerated area by 50%) were decreased from 36.5 to 13.5 mg/kg in natural healing and from 76.0 to 23.0 mg/kg in delayed healing. Aggravation of four-week-old ulcers by indomethacin was significantly prevented by daily administration of NC-1300 (30 or 100 mg/kg) for four weeks. Acetic acid ulcers that were healed with NC-1300 given for four weeks after ulceration remained healed for four to eight weeks after the cessation of drug administration. A single administration of NC-1300 to normal rats and repeated administration of NC-1300 to rats with acetic acid ulcers for four weeks after ulceration caused the same degree of inhibition of gastric acid secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed Healing of Acetic Acid-Induced Gastric Ulcers in Rats by Indomethacin

We examined the mechanism by which repeated administration of indomethacin significantly delays the natural healing of experimental gastric ulcers induced in rats. Gastric ulcers were produced 5 days after injecting 20% acetic acid (0.03 ml) into the submucosal layer of the gastric wall of the antral-oxyntic border. The natural healing of the acetic acid-induced ulcers was extensively delayed by administering indomethacin (1 mg/kg) subcutaneously once daily for 2 or 4 wk. Subcutaneous administration of natural prostaglandin E2 (1 or 3 mg/kg) twice daily for 2 and 4 wk, together with indomethacin, significantly prevented the delay of ulcer healing. Prostaglandin E2 (3 mg/kg) administered twice daily for 2 wk also significantly accelerated the natural healing of the ulcers. A single administration of prostaglandin E2 (1 or 3 mg/kg) significantly reduced histamine-stimulated gastric acid secretion for 4 h in acute fistula rats with 1- or 2-wk-old ulcers, treated with or without daily indomethacin (1 mg/kg). Endogenous prostaglandin E2 levels in the gastric mucosa of normal rats were significantly reduced for at least 12 h after a single or repeated administration of indomethacin (1 mg/kg) for 2 or 4 wk. Gastric mucosal prostaglandin E2 levels in rats with ulcers (5 days after acetic acid injection) were also markedly reduced by indomethacin. This reduction significantly reverted toward control levels after administration of exogenous prostaglandin E2 (3 mg/kg). These results suggest that endogenous prostaglandin E2 plays an important role in the healing process of gastric ulcers.

Influence of Prostaglandins, Omeprazole, and Indomethacin on Healing of Experimental Gastric Ulcers in the Rat

We investigated whether the trophic actions of prostaglandins, omeprazole, and indomethacin on gastric mucosa lead to accelerated healing of gastric ulcers in the rat. Cryoulcers were produced in the corpus area and treated with 16,16-dimethyl prostaglandin E2 (5 or 100 μg/kg b.i.d., intragastrically), omeprazole (40 μmol/kg once daily, subcutaneously), indomethacin (2 mg/kg b.i.d., subcutaneously), or placebo. At the end of the treatment, plasma gastrin, cell labeling index (autoradiography with [3H]thymidine), and the size and depth of mucosal defects were measured. Compared with placebo, omeprazole accelerated ulcer healing as indicated by a smaller ulcer area [1.1 ± 0.2 vs. 4.8 ± 1.2 mm2 (mean ± SEM)] and smaller ulcer depth (383 ± 31 vs. 488 ± 41 μm) after 10 days of treatment. Prostaglandins did not affect ulcer healing despite thickening of gastric corpus mucosa. Indomethacin delayed ulcer healing and reduced the labeling index. Omeprazole induced a marked hypergastrinemia (208 -F 12 vs. 66 ± 12 pmol/L on day 5, and 469 ± 23 vs. 58 ± 16 pmol/L on day 10). The results indicate that abolishment of acid secretion by omeprazole accelerates healing. Trophic actions and “cytoprotective” effects by prostaglandins are not relevant for ulcer healing in this model.

Effects of beta-adrenoceptor drug stimulation on various models of gastric ulcer in rats.

1. Experiments were designed to evaluate the effect of the pharmacological activation of beta-adrenoceptors on various models of gastric ulcer in the rat. 2. Pretreatment with the beta-adrenoceptor stimulant drugs, isoprenaline or salbutamol, significantly inhibited stress-induced gastric ulcers. This anti-ulcer effect was abolished by propranolol but not by atenolol, suggesting that beta 2-adrenoceptors mediate this response. 3. In the pylorus-ligation model, salbutamol inhibited lesion formation and reduced the intragastric content of hydrogen ions, histamine and pepsin although the latter was only affected with the higher dose of salbutamol. 4. Salbutamol also prevented the ulcerogenic action on the gastric mucosa of an exogenously perfused artificial gastric juice, showing that the anti-ulcer effect is not necessarily dependent on acid inhibition. 5. Salbutamol also reduced the formation of acute ulcers induced by various iatrogenic means (histamine, polymyxin B, reserpine and indomethacin). 6. Long-term treatment with salbutamol accelerated the healing of experimental chronic gastric ulcer. 7. In anaesthetized rats, salbutamol produced a dose-related increase in mucosal blood flow which may contribute to its mode of action. 8. It is concluded that beta-adrenoceptor agonists exert preventive and curative effects on gastric damage induced in the rat. This effect seems specific and mediated through beta-adrenoceptor activation.

Changes in fibrinolytic, coagulative and kinin systems in healing of experimental gastric ulcer

Close relation of an experimental gastric ulcer development to coagulative, fibrinolytic and kinin systems has been widely recognized. In the present study, the fluctuations of coagulative, fibrinolytic and kinin systems in passage of time were compared against the morphological alteration in the ulcer healing process. Male adult beagles were used as experimental animals, and an acute gastric ulcer (UL-II) was produced in each by contact freezing of the branches of gastric arteries on the serosal side in the lower corpus. The tissue plasminogen activator levels in the ulcer region, surrounding embankment and in distant normal regions continually lowered for 24 hours, after which they all recovered to the normal levels. The plasma plasmin inhibitor levels started to be elevated after the passage of 24 hours, but returned to their normal range in 2 weeks. The plasma plasminogen stayed relatively unchanged throughout the process. The coagulation factors V and VIII were low untill the end of the 2nd week, after which they returned to normal. The kinin like peptide activity was low throughout the first week, showed marked release in the 2nd week, and was restored to normal at the end of the 4th week. The histologic view and microangiogram revealed repair and a marked change in fine vessels consisting of variegated and dense hyperplasia in the 2nd week, while the coagulative, fibrinolytic and kinin systems also underwent changes of a similar pattern, which indicates that the former was correlated to the latter.

Effect of Diet on the Healing of Experimental Gastric Ulcer.

Effect of Diet on the Healing of Experimental Gastric Ulcer.

Effect of Diet on the Healing of Experimental Gastric Ulcer

Ferguson was able to produce uniformly in rabbits gastric ulcers which persisted from 2 to 8 months or longer. He incised the anterior wall of the stomach and at the point of incision removed a piece of mucosa and then closed the stomach by a silk suture, the rabbits being kept on a diet of hay, oats and carrots. It occurred to us that this observation provided a method of studying the effect of diet on the healing of this experimental gastric ulcer. In our first series of rabbits we found that if a lesion was made in the posterior wall of the stomach in which no silk suture was present and one in the anterior wall in which a silk suture was present and the rabbits placed on the stock diet of hay, oats and carrots, that the posterior lesion healed in 30 days, but the anterior lesion did not. This showed that the silk suture was a factor in delaying healing and that in the absence of the silk, diet played no rôle in delaying healing. Anterior lesions of the Ferguson type were made in 29 rabbits. Twelve were placed on the stock diet and 17 on a diet of milk, bread and mashed boiled carrots. The rabbits were sacrificed on the 30th day. All of the 12 rabbits on the “rough diet” had ulcers at the 30th day. Only 3 of the 17 on the “soft diet” had ulcers. The results show that the silk suture per se is not sufficient to prevent the ulcer from healing and that a “rough diet” plus the silk suture factor are sufficient to produce a chronic gastric ulcer, grossly and histologically, and that a “soft diet” favors the healing of gastric lesions.