Gastric Healing Research Articles

Helicobacter pylori attenuates the delay in ulcer healing induced by aspirin and selective COX-2 inhibitor

Helicobacter pylori (H. pylori) and NSAIDs are recognized as major pathogenic factors in peptic ulcer disease. However, whether these two factors exert synergistic or antagonistic effects on ulcer healing has not yet been fully explained. In this study, the effects of aspirin (ASA) alone and rofecoxib, a specific prostaglandin cyclooxygenase (COX)-2 inhibitor, were compared with that of ASA and rofecoxib applied in combination with H. pylori on gastric acid secretion and healing of acetic acid ulcers in rats. The H. pylori colonization of gastric mucosa was determined by viable bacterial culture and histology. The area of ulcers was determined by planimetry, the gastric blood flow (GBF) was measured using the H2-gas clearance method and the gastric mucosal generation of PGE2 and plasma gastrin levels were assessed by radioimmunoassay. ASA or rofecoxib applied alone delayed significantly the healing of chronic gastric ulcers and this effect was accompanied by a marked decrease in the GBF at the ulcer margin and gastric mucosal PGE2 generation without significant influence of gastric acid output. H. pylori that produced moderate gastric inflammation at the ulcer margin as confirmed by bacterial culture, prolonged significantly the healing of these ulcers and decreased the GBF at the ulcer margin and gastric acid output while elevating significantly the gastric mucosal PGE2 generation and plasma gastrin levels. H. pylori attenuated significantly the ASA- and rofecoxib-induced inhibition of ulcer healing and accompanying fall in the GBF at the ulcer margin and reversed, in part, the ASA- and rofecoxib-induced alterations in PGE2 generation. We conclude that H. pylori attenuates the delay in ulcer healing induced by ASA and rofecoxib due to enhancement in the generation of endogenous PGE2 and gastrin release, as well as suppression of acid secretion which may limit deleterious influence of NSAID on ulcer healing.

Role of endogenous prostacyclin in gastric ulcerogenic and healing responses: A study using IP-receptor knockout mice

Role of endogenous prostacyclin in gastric ulcerogenic and healing responses: A study using IP-receptor knockout mice

Role of endogenous prostacyclin in gastric ulcerogenic and healing responses: A study using IP-receptor knockout mice

Role of endogenous prostacyclin in gastric ulcerogenic and healing responses: A study using IP-receptor knockout mice

Portal hypertensive gastric mucosa has reduced activation of MAP kinase (ERK2) in response to alcohol injury: a key to impaired healing?

Portal hypertensive (PHT) gastric mucosa has increased susceptibility to injury and impaired mucosal healing. Because our previous study showed that ulcer-induced activation of mitogen-activated protein (MAP) kinase (ERK) plays a pivotal role in gastric mucosal healing, we investigated whether ERK activation is altered in PHT gastric mucosa following alcohol injury. We studied ERK2 phosphorylation and activity and expression of MAP kinase phosphatase-1 (MKP-1) in gastric mucosa of PHT and sham-operated (SO) normal rats both at baseline and following alcohol injury. In SO gastric mucosa, ERK2 phosphorylation and activity were significantly increased time-dependently following alcohol injury: by 221% and 137%, respectively at 24 h vs. baseline. In contrast, in PHT gastric mucosa following alcohol injury, neither ERK2 phosphorylation nor activity was increased versus baseline. In PHT gastric mucosa, MKP-1 mRNA and protein expression were increased at baseline versus SO rats and were increased further following alcohol injury with values higher by 20%-40% at each study time versus SO rats. Because ERK2 is crucial for mucosal healing, reduced ERK2 activation resulting from the overexpression of MKP-1 might be the basis for the impaired mucosal healing in PHT gastric mucosa.

Gastropathy and NSAIDs

DirectorAcute Pain ServiceAssociate Professor of AnesthesiologyBaystate Medical Center and the Tufts University School of Medicine Springfield, Massachusettsscott.reuben@bhs.orgIn Reply:—Although we agree that this patient was at increased risk for development of gastropathy because of her older age and history of peptic ulcer disease, we did not believe this was a contraindication to the use of celecoxib. Although the package insert for celecoxib 1states that “significant upper GI bleeding” has occurred with celecoxib, the reported incidence was only 2 of 5,285 (0.04%) patients. In addition, a randomized controlled study 2that evaluated the safety and efficiency of 200–800 mg/day celecoxib compared with 1,000 mg/day naproxen or with placebo revealed no statistically significant differences in the incidence of gastroduodenal ulcers between the placebo group and any of the celecoxib groups (P > 0.40). In contrast, the incidence of ulceration in the naproxen group was significantly greater than in each of the other treatment groups (P < 0.001). Patients who were elderly or had a history of peptic ulcer disease were not excluded from this study. In fact, neither of these risk factors was associated with an increased risk for ulceration in any of the celecoxib groups. Therefore, we believed that celecoxib was a safer alternative to naproxen for our patient who received excellent analgesia from previous nonsteroidal antiinflammatory drug (NSAID) therapy.In addition, we elected to administer omeprazole in conjunction with celecoxib therapy to facilitate gastric healing. The healing effectiveness of omeprazole does not appear to be compromised by the continued use of NSAIDs. 3Despite these measures, a gastric perforation still developed in our patient. As discussed in our case report, 4we believe that blocking the production of prostaglandins derived from COX-2 may be deleterious in the setting of a recent gastric mucosal injury. The previous cited studies 1,2that evaluated the risk of gastrointestinal tract ulceration during the administration of celecoxib did not include patients with a recent history (≤ 30 days) of peptic ulcer disease.Although we believe COX-2 inhibitors are safer alternatives to standard NSAIDs in the presence of peptic ulcer disease, perhaps alternative analgesic therapy should be initiated in the presence of a recent gastroduodenal ulcer.

Polyamines are required for microtubule formation during gastric mucosal healing.

Polyamines are essential for the repair of gastric and duodenal erosions. Concentrated NaCl (3.4 M) given intragastrically damages the oxyntic gland mucosa and increases the activity of gastric mucosal ornithine decarboxylase (ODC), the first rate-limiting enzyme in polyamine synthesis. The nature of the process of restitution of damaged mucosa is not well known, except that cell migration and the actin cytoskeleton play a prominent role. Microtubules are cytoskeletal components essential for cell migration. The present investigation determines the relationship between polyamines, the distribution of microtubules, and gastric healing in mucosa damaged with hypertonic NaCl solution. Rats were fasted for 22 h and then given 1.0 ml of 3.4 M NaCl intragastrically. Animals were killed 1, 2, 4, 8, and 10 h after 3.4 M NaCl. The oxyntic gland mucosa was removed, and tubulin was visualized by immunofluorescence. Microtubule density was increased around and below the damaged mucosa in the upper one-third of the glandular epithelium at 2 and 4 h and returned to near control levels by 10 h. In rats damaged with 3.4 M NaCl and pretreated intraperitoneally with alpha-difluoromethylornithine (DFMO), a specific inhibitor of ODC, microtubule content was reduced significantly at all time points after NaCl treatment. Addition of spermidine after pretreatment with DFMO and 3.4 M NaCl significantly prevented the effects of DFMO. Colchicine, a potent microtubule-disrupting drug, significantly delayed normal gastric mucosal healing with no effect on ODC activity. These data show that polyamines influence the distribution of microtubules during damage in vivo and indicate a partial mechanism for the dependency of mucosal healing on polyamines.

Pepsinogen C gene product is a possible growth factor during gastric mucosal healing

We isolated, by the subtraction cloning method, a pepsinogen C (PGC) gene fragment (the sequence between the 968th and 1179th base pairs) from a rat gastric mucosal cDNA library as a cDNA clone encoding a substance that promotes growth of the normal rat gastric mucosal cell line RGM1. Northern blot analysis revealed that PGC gene expression was enhanced not only in acetic acid-induced chronic gastric ulcers but also in indomethacin-induced gastric mucosal lesions. PGC gene expression was also increased in the Helicobacter felis-infected stomachs. Thus, the PGC gene may play a role in gastric epithelial cell growth during gastric mucosal healing.

A novel zinc derivative agent, polaprezinc, prevented the toxicity of bile acid and H2O2 on gastric epithelial cells in a cell culture model

Zinc is an essential trace mineral and many enzymes including DNA and RNA polimerases depend on its presence. Therefore, zinc may play a role in a gastric wound healing. We have reported that zinc and its derivative, poloprezinc (PZ), induced IGF-I production from mesenchymal cells, resulting in stimulation of gastric epithelial restoration through paracrine pathways. In this study, we assessed the effects of PZon the toxicity of deoxycholic acid (DCA) and H202 to gastric epithelial cell migration, proliferation and apoptosis using an in vitro wound healing model (Gastro. 110:775,1996). METHODS: Isolated rabbit gastric epithelial cells formed complete polarized monolayer. A round-shaped wound with constant size was created by mechanical cell denudation and the restoration process was monitored by measuring wound size for up to 48 h. DCA (1-140 p M) or H202 (0.1-3mM) with or without PZ (1-100 p M) was added to the medium at wounding. Cell proliferation was assessed by BrdU staining and apoptosis was measured using the TUNEL method and DNA ladder detection. RESULTS: Sequential change of wound size is shown in the table (mm 2, mean _+ SD, n=5, *p<0.05 vs control)

Effects of cyclooxygenase-2 selective and nitric oxide-releasing nonsteroidal antiinflammatory drugs on mucosal ulcerogenic and healing responses of the stomach.

Effects of selective cyclooxygenase-2 (COX-2) inhibitors (NS-398) and nitric oxide (NO) -releasing aspirin (NO-ASA) on gastric ulcerogenic and healing responses were examined in comparison with nonselective COX inhibitors such as indomethacin and aspirin (ASA). Hypothermic stress (28-30 degrees C, 4 hr) induced gastric lesions in anesthetized rats with an increase of acid secretion. The lesions induced by hypothermic stress were markedly worsened by subcutaneous administration of both indomethacin and ASA but were not affected by either NS-398 or NO-ASA, although the increased acid secretion during hypothermia was not affected by any of the drugs. On the other hand, the healing of gastric ulcers induced in mice by thermal cauterization (70 degrees C, 15 sec) was significantly delayed by daily subcutaneous administration of indomethacin and ASA as well as NS-398, but not by NO-ASA. COX-2 mRNA was not detected in the intact mucosa but was positively expressed in the ulcerated mucosa, most potently on day 3 after ulceration. Prostaglandin contents in the intact mouse stomach were reduced by indomethacin, ASA, and NO-ASA, while the increased prostaglandin generation in the ulcerated mucosa was inhibited by all drugs including NS-398. After subcutaneous administration of NO-ASA to pylorus-ligated rats and mice, high amounts of NOx were detected in both the gastric contents and serum. In addition, both NS-398 and NO-ASA showed an equipotent antiinflammatory effect against carrageenan-induced paw edema in rats as compared with indomethacin and ASA. These results suggest that both indomethacin and ASA not only increased the mucosal ulcerogenic response to stress but impaired the healing response of gastric ulcers as well. The former action was due to inhibition of COX-1, while the latter effect was accounted for by inhibition of COX-2 and was mimicked by the COX-2-selective inhibitor NS-398. NO-ASA, although it inhibited both COX-1 and COX-2 activity, had no deleterious effects on gastric ulcerogenic and healing responses.

Glutathione and N-acetylcysteine reduce gastric mucosal blood flow in rats.

Glutathione has been studied as a possible mediator in gastric mucosal protection and healing, but its extracellular function is not fully understood. This study evaluates blood flow changes in normal gastric mucosa secondary to glutathione modulation under stable central hemodynamic conditions. Thiol substances were quantified by reverse-phase ion-pair liquid chromatography and fluorescence detection. Central hemodynamics remained stable when glutathione and N-acetylcysteine were administered in a dose of 0.5 mmol/kg. Higher doses than 0.5 mmol/kg of glutathione and N-acetylcysteine caused unstable hemodynamics. Glutathione (0.5 mmol/kg intravenously) and N-acetylcysteine (0.5 mmol/kg intravenously) reduced corpus mucosal blood flow by 28% and 26% (P < 0.0005), respectively, and glutathione reduced antral mucosa blood flow by 22% (P < 0.01). L-Buthionine-[S,R]-sulfoximine (2 mmol/kg intravenously) did not effect gastric mucosal blood flow. Cysteine content in mucosa and plasma increased while mucosal glutathione levels were largely unchanged after administration of reduced glutathione and N-acetylcysteine. Plasma glutathione only increased after injection of glutathione. L-Buthionine-[S,R]-sulfoximine reduced the glutathione level in both plasma and mucosa. We conclude that glutathione and N-acetylcysteine reduce gastric mucosal blood flow and that the effect may be related to increased cysteine levels in plasma or mucosa.

Relationship between polyamines, actin distribution, and gastric healing in rats.

Intragastric administration of 3.4 M NaCl damages the gastric mucosa and increases the activity of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine synthesis. Polyamines are essential for the repair of gastric erosions. Little is known about the restitution of damaged mucosa except that cell migration is essential. Actin is the principal cytoskeletal protein and is essential for migration. This investigation determines the relationship between polyamines, actin, and gastric healing. Rats were fasted for 22 h and given 1.0 ml of 3.4 M NaCl intragastrically and killed 1, 2, 4, 8, and 10 h later. The mucosa was assayed for ODC activity and stained for G- and F-actin. F-actin was concentrated below the damaged mucosa at 1.5, 2, and 4 h. There was no increase in F-actin distribution at any time point, when NaCl-treated animals were given alpha-difluoromethylornithine (DFMO), a specific inhibitor of ODC. In addition, DFMO significantly prevented the healing of the mucosal lesions. Spermidine treatment after DFMO + NaCl significantly prevented the effects of DFMO. Cytochalasin D, a potent actin-disrupting drug, significantly delayed normal gastric mucosal healing. The endogenous polyamines increased significantly in NaCl animals. Data indicate that increases in polyamine synthesis after damage influence the distribution of F-actin in vivo, which may play a part in the healing of mucosal erosions.

Gastric wound healing in monolayer cell culture

Gastric wound healing in monolayer cell culture

Transendoscopic electrocautery‐induced gastric ulcers as a model for gastric healing studies in ponies

The ponies were apparently healthy and 6-20 months of age. In Study 1, gastric lesions were created by transendoscopic electrocautery in the non-glandular gastric mucosa, adjacent to the margo plicatus in 9 ponies which were then treated with water, 12 mg cimetidine HCl/kg bwt or 18 mg cimetidine HCl/kg bwt per os every 12 h for 35 days. In Study 2, gastric lesions were similarly induced in 9 ponies in the non-glandular mucosa and also in the glandular mucosa just below the non-glandular lesion on the greater curvature of the stomach. The ponies were treated with water, 8 mg cimetidine/kg bwt or 16 mg cimetidine/kg bwt per os every 8 h for 21 days. In both studies gastric lesion healing was monitored twice weekly by video gastroscopy. There was no apparent difference in healing times between the water and cimetidine treatment groups in either study. These results indicate that uniform gastric ulcers can be created by transendoscopic electrocautery in the non-glandular mucosa of ponies and that these ulcers heal at a predictable rate which should be useful in studying compounds that might accelerate healing of gastric mucosal lesions. However, cimetidine was not effective in accelerating the rate of healing under the conditions of this study.

Effect of ranitidine on healing of experimentally induced gastric ulcers in ponies

Summary Thirty young ponies were examined endoscopically for evidence of gastric ulceration. Seven ponies had noninduced gastric ulcers present at the initial examination and were eliminated from the study. In an attempt to induce gastric ulcers experimentally, flunixin meglumine (1.1 mg/kg of body weight, im, q 8 h) was administered for 7 days to the 23 ponies with endoscopically normal gastric mucosa. During the 7 days of flunixin administration, 11 ponies developed gastric ulcers that were appropriate for study. The 11 ponies were randomly allotted to 2 groups. Group-A (n = 5) and group-B (n = 6) ponies received ranitidine (4.4 mg/kg, po, q 8 h) and corn syrup, respectively, until ulcers healed or for a maximum of 40 days. General anesthesia was induced every 3 to 5 days for visual evaluation of ulcer healing by use of a video endoscope. The earliest complete healing of gastric lesions observed in a corn syrup-treated pony was at 17 days. At 40 days, 3 of 5 and 3 of 6 ponies of the ranitidine and corn syrup-treated groups, respectively, had healed ulcers. Results of this study indicate that: noninduced gastric ulcers may be common in young ponies, flunixin meglumine may be effective in inducing gastric ulcers for gastric healing studies in young ponies, and ranitidine (4.4 mg/kg, q 8 h) is not significantly effective in accelerating healing of experimentally induced gastric ulcers in ponies under conditions of this study.

Effects of Prednisolone and Human Epidermal Growth Factor on Angiogenesis in Granulation Tissue of Gastric Ulcer Induced by Acetic Acid

In an attempt to elucidate the role of granulation vessels in the healing of gastric ulcer, healing and angiogenesis in granulation tissue of acetic acid ulcers were studied in rats. In addition, the effects of prednisolone and synthetic human epidermal growth factor (EGF) on angiogenesis and ulcer healing were investigated. The newly formed granulation vessels in the ulcer base were measured by means of a carmine dye infusion method. Prednisolone, administered subcutaneously at 40 mg/kg/day, significantly decreased angiogenesis in the ulcer base on the 10th day after ulcer production, and on the 30th day ulcer healing was found to be significantly delayed. In contrast, angiogenesis was significantly increased, and ulcer healing was enhanced by intragastric administration of 100 micrograms/kg/day of EGF. With combined administration of prednisolone and EGF, angiogenesis was significantly increased compared to that observed with prednisolone treatment alone. The authors conclude that suppression of angiogenesis by prednisolone is a delaying factor in gastric ulcer healing and that exogenous EGF promotes ulcer healing, partly through restoration of angiogenesis.

Stimulatory effect of enprostil, an anti-ulcer prostaglandin, on gastric mucus secretion

Enprostil, a synthetic analogue of prostaglandin E2, is known to be a potent inhibitor of gastric acid secretion, and has marked anti-ulcer activity in rodents. Enprostil was administered in doses ranging from 15 to 250 micrograms/kg to rats prepared using the Shay procedure. Three hours later, the rats' stomachs were removed and processed either for the chemical determination of mucus, or for scanning electron microscopy. For the chemical determination, the secreted gastric juice was removed and the adherent gastric mucus was eluted with 2 M sodium chloride. The anthrone method was used to determine the mucus present. Enprostil was found to significantly increase gastric mucus at a dose of 60 micrograms/kg when measured by the anthrone test. Enprostil administered by the oral route was most effective in stimulating mucus secretion, suggesting a local or topical action of enprostil on mucus-secreting cells. Scanning electron microscopy of rat fundic mucosa after enprostil administration (50 to 100 micrograms/kg) revealed the presence of thin veil-like layers covering the epithelial surface, which was interpreted as an increase in mucus secretion. Higher magnifications (X 2,000) clearly showed the layers of mucus covering the surface epithelial cells. Enprostil's apparent increase of gastric mucus secretion may contribute to its anti-ulcer activity and may promote gastric healing.