Gastroprotective Effects of Grape Seed Proanthocyanidin Extracts against Nonsteroid Anti-Inflammatory Drug-Induced Gastric Injury in Rats

Background/Aims

To investigate the gastroprotective effects of grape seed proanthocyanidin extracts (GSPEs) against nonsteroid anti-inflammatory drug (NSAID)-induced gastric mucosal injury in rats.

Methods

Sprague-Dawley rats were randomly allocated to the normal control, indomethacin, low-dose GSPE, high-dose GSPE and misoprostol groups. All groups except the normal control group received pretreatment drugs for 6 consecutive days. On the 5th and 6th day, indomethacin was administered orally to all groups except for normal control group. The microscopic features of injury were analyzed. The levels of gastric mucosal glutathione, gastric mucosal prostaglandin E₂ (PGE₂), and proinflammatory cytokines were investigated.

Results

The total areas of ulceration in the GSPE and misoprostol groups were significantly decreased compared with the indomethacin group (p<0.05). However, a difference in ulcer formation among the drug treatment groups was not observed. Meanwhile, the glutathione levels in the high-dose GSPE group were higher than those of both the indomethacin and misoprostol groups (p<0.05) and were similar to those of the normal control group. Additionally, there was no difference among the groups in the levels of gastric mucosal PGE₂ and proinflammatory cytokines.

Conclusions

High-dose GSPE has a strong protective effect against NSAID-induced gastric mucosal injury, which may be associated with the antioxidant effects of GSPE.     

Effect of exogenous administration of transforming growth factor-beta and famotidine on the healing of duodenal ulcer under the impact of indomethacin

BACKGROUND: Non-steroidal anti-inflammatory drugs delay ulcer healing and cause refractory peptic ulcers in humans. OBJECTIVE: To study the effects of growth factors on experimental duodenal ulcer healing in indomethacin-treated rats. METHODS: Duodenal ulcers were induced in male Wistar rats by the serosal application of 75% acetic acid for 10 s. Rats were then treated with indomethacin (2 mg/kg/day; s.c.), transforming growth factor beta (15 ng locally injected subserosally at the ulcer site) or famotidine (5 mg/kg/day; p.o.), vehicle or combinations of treatments. On day 5, 8 or 12, rats were sacrificed and the ulcer area planimetrically measured under a dissecting microscope. Macroscopic area, microscopic diameter, collagen content and mucosal regeneration were assessed in histological preparations. Gastric secretion was assessed also in the pylorus-ligated rat-model. Data expressed as median and ranges were analyzed by non-parametric test. RESULTS: Indomethacin delayed ulcer healing but transforming growth factor-beta and famotidine improved ulcer healing and reversed the effects of indomethacin. Maximal differences were observed on day 8. Transforming growth factor-beta was associated with an increase in epithelial and granulation tissue cell proliferation. Famotidine induced a profound inhibition of gastric secretion and increased collagen secretion but it did not affect cell proliferation. CONCLUSIONS: Transforming growth factor-beta and famotidine accelerate ulcer healing delayed by indomethacin.     

Healing property of the Piper betel phenol, allylpyrocatechol against indomethacin-induced stomach ulceration and mechanism of action

AIM：To evaluate the protective activity of allylpyrocatechol （APC）, the major antioxidant constituent of Piper betel, against the indomethacin-induced stomach ulceration in the rat model and correlates with its antioxidative and mucin protecting properties.
METHODS： Male Sprague-Dawley rats were divided into five groups. Normal control rats （group Ⅰ ） were given the vehicle oral dose of gum acacia in distilled water （1 mL per rat）; ulcerated control and treated rats （groups Ⅱ-V） were given a single dose of indomethacin （30 mg/kg body wt.）; group Ⅱ rats were sacrificed 4 h after indomethacin administration; groups Ⅲ-Ⅴ rats were given the vehicle （1 mL per rat） or APC （2 mg/kg body wt.） or misoprostol （1.43 μg/kg body wt.） once daily by oral intubation for 7 d starting from 4 h after the indomethacin administration. After 7 d, the stomach tissues were excised for histological examination and biochemical analysis.
RESULTS： Treatment with APC （2 mg/kg body wt per day） and misoprostol （1.43 μg/kg body wt per day） for 7 d could effectively heal the stomach ulceration as revealed from the ulcer index and histopathological studies. Compared to the zero day ulcerated group, treatment with APC and misoprostol reduced the ulcer index by 93.4% and 85.4% respectively （P 〈 0.05）. Both APC and misoprostol accelerated ulcer healing observed in natural recovery （P 〈 0.05）, their respective healing capacities not being significantly different. The healing capacities of APC and misoprostol could be attributed to their antioxidant activity as well as the ability to enhance the rnucin content of the gastric tissues. Compared to the ulcerated untreated rats, those treated with APC and rnisoprostol showed near normal MDA levels, while the protein levels were 86% and 78% of the normal value respectively （P 〈 0.05）. Likewise, both APC and rnisoprostol increased the SOD, catalase, and rnucin levels significantly （P 〈 0.05）, the effect of APC being better.     

Tiaprofenic acid inhibits mucosal prostaglandin E2 synthesis without delaying experimental gastric ulcer healing

Increasing evidence suggests that non-steroidal anti-inflammatory drugs (NSAID) differ in gastrotoxicity. This study aimed to compare the effects of a short-acting NSAID, tiaprofenic acid, with indomethacin on experimental gastric ulcer healing in a rat model. Similar anti-inflammatory and prostaglandin-inhibitory doses of indomethacin (1mg/kg) and tiaprofenic acid (2mg/kg) were administered to rats with acetic acid-induced ulcers. After 2 weeks treatment, rats were killed and ulcer size determined. In addition, histological sections of ulcers were assessed for ulcer contraction and mucosal regeneration. The degree of inhibition of prostagiandin E₂ (PGE₂) synthesis was 72% at 2h after tiaprofenic acid and 64% at 2h after indomethacin administration, respectively. Rats treated with indomethacin for 2 weeks had significantly larger ulcers, both macroscopically and microscopically, than controls. Rats treated with tiaprofenic acid for 2 weeks had ulcers of a similar size to those of controls. Indomethacin-treated ulcers showed a failure in mucosal regeneration. Tiaprofenic acid-treated ulcers had significantly more regeneration than indomethacin-treated ulcers. We conclude that tiaprofenic acid inhibits mucosal prostaglandin levels but does not inhibit experimental gastric ulcer healing. These findings suggest that inhibition of PGE₂ synthesis is not the only factor in generating gastrotoxicity and that a shift to low gastrotoxic NSAID may be clinically worthwhile.     

Effects of misoprostol on delayed ulcer healing induced by aspirin

Clinical studies have suggested that treatment with the prostaglandin E₁ analog, misoprostol, leads to significant healing of ulcers in patients taking regular nonsteroidal antiinflammatory therapy. This study aimed to investigate mechanisms involved in this healing using a rat model. Gastric ulcers were induced by application of acetic acid using a standard technique. Rats were treated with 200 mg/kg aspirin, 100 µg/kg misoprostol, a combination of both treatments, or methylcellulose vehicle for up to two weeks, starting two days after ulcer induction. Ulcers were assessed by macroscopic measurements of area and by quantitative histological measurements. Aspirin delayed ulcer healing compared with controls, while misoprostol significantly reversed this effect. Quantitative histology revealed that misoprostol cotreatment significantly increased mucosal regeneration compared with aspirin treatment alone. However, misoprostol did not reverse the effects of aspirin on an index of wound contraction. We conclude that treatment with misoprostol significantly reverses the delayed healing effect of aspirin, and this may occur via an effect on epithelial regeneration.This study was supported by a grant from the Alfred Hospital Medical Research Advisory Committee.     

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.     

Healing process of duodenal ulcers induced by indomethacin plus histamine in rats

Healing of duodenal ulcers induced by indomethacin + histamine was investigated in rats. Animals were treated with indomethacin (5 mg/kg, s.c., once daily) and histamine (40 mg/kg, s.c., 3 times every 2.5 h after indomethacin treatment) for 2 days under fasting conditions, and they were fed normally thereafter. The duodenal ulcers so induced were confined to the proximal part of the duodenum and penetrated to the muscular mucosa with an incidence of over 80% when determined 32 h after the first injection of indomethacin (day 1). The ulcers became smaller and shallower within 7 days with granulation from the ulcer base, the mucosa grew in from the edges over the surface of granulation tissue, and they had healed almost completely after 15 days with epithelial regeneration from the edge of the ulcers. The healing of ulcers was significantly promoted by a 5-day treatment with an antacid (Al(OH)3) as well as antisecretory agents (omeprazole, cimetidine, propantheline bromide) and 16,16-dimethyl prostaglandin E2 at the dose which produced a potent inhibition of acid output and a marked increase in duodenal alkaline secretion. These results suggest that the duodenal ulcers induced in rats by indomethacin + histamine may provide a useful model for studying the healing process of duodenal ulcers and for the evaluation of the drugs with possible effects on ulcer healing.     

Effects of leminoprazole, omeprazole and sucralfate on indomethacininduced delayed healing of kissing gastric ulcers in rats

We have examined whether or not repeated treatment with indomethacin delays the healing of kissing gastric ulcers induced in rats. The effects of leminoprazole, omeprazole and sucralfate on any delay in ulcer healing caused by indomethacin were also determined in relation to myeloperoxidase activity. Kissing gastric ulcers were induced by luminal application of an acetic acid solution. Indomethacin significantly delayed ulcer healing in a dose-dependent manner. Leminoprazole and omeprazole decreased the size and depth of ulcers, the healing of which was delayed by indomethacin, while sucralfate only decreased the ulcer depth. Histological studies showed that indomethacin inhibited tissue contraction and regeneration of the ulcerated mucosa. Leminoprazole and omeprazole prevented the inhibition of these parameters. The myeloperoxidase (MPO) activity of the ulcer portion in animals treated with indomethacin was markedly higher than in the control group. Both leminoprazole and omeprazole, but not sucralfate, significantly reduced MPO activity in contrast to the control value (in the presence of indomethacin). There was a significant relationship between the ulcerated area and myeloperoxidase activity. These results suggested that: (i) leminoprazole and omeprazole prevent the indomethacin-induced delay in ulcer healing by promoting tissue contraction and regeneration of the ulcerated mucosa; (ii) sucralfate prevents the indomethacin-induced delay in ulcer healing via the promotion of the formation of granulation tissue; and (iii) MPO activity will be useful to biochemically ensure the healing state of ulcers.     

Comparative mucosal protective properties of misoprostol,cimetidine, and sucralfate

Misoprostol, a PGE₁ derivative that inhibits gastric acid secretion in rats, was compared with cimetidine and sucralfate in several rat experimental ulcer models. Gastric lesions were produced by aspirin, indomethacin, stress, sodium taurocholate, and ethanol. In all tests, misoprostol (50, 100, and 200 μg/kg) and cimetidine and sucralfate (50, 100, and 200 mg/kg) were administered intragastrically. Misoprostol protected against gastric lesions in all five experimental ulcer models at lower than gastric antisecretory doses. Cimetidine protected in the indomethacin, aspirin, and stress models, but only at gastric antisecretory doses, and did not protect against lesion formation in the ethanol and taurocholate models. Sucralfate, over the dose range tested, was not consistently protective in any of the five experimental ulcer models. It is concluded that misoprostol provides gastric mucosal protection against a wide variety of noxious agents by means of a unique mechanism and that reduction of gastric acid secretion is not required, as it is with cimetidine, for the protective effect.     

Influence of age on natural and delayed healing of experimentally-induced gastric ulcers in rats

This study aimed to investigate the effect of age on natural ulcer healing and delayed ulcer healing induced by nonsteroidal antiinflammatory drugs, using a rat model. Gastric ulcers were induced in young, adult, and aged rats using serosal or mucosal (kissing ulcers) application of acetic acid. Rats were treated with indomethacin 1 mg/kg/day subcutaneously or vehicle for two weeks. Ulcers were assessed by macroscopic and histological measurements of ulcer size. Ulcer induction was affected by age. Aged rats developed significantly smaller ulcers when induced by serosal application of acetic acid and significantly larger ulcers from mucosal application of acetic acid. However, measurements of ulcer size from both models showed no age-related differences in natural ulcer healing. Similarly, indomethacin-induced delayed gastric ulcer healing was not effected by age. We conclude that there are age-related differences in the development of gastric ulcers but there are no age-related differences in natural or delayed ulcer healing in rats.This study was supported by grants from the Sandoz Foundation for Gerontological Research, Australia and Perpetual Trustees, Australia.     

清肠栓调节三硝基苯磺酸诱导结肠炎大鼠结肠黏膜细胞增殖的影响

[目的]从细胞增殖动力学角度探讨清肠栓促进结肠溃疡愈合的作用机制.[方法]制备三硝基苯磺酸(TNBS)诱导结肠炎大鼠.造模3 d,分为清肠栓高剂量组、清肠栓低剂量组、柳氮磺胺吡啶(SASP)组、模型对照组、模型组和正常组.给药7 d后,取大鼠结肠病变部位标本,进行组织学评价,运用AB-PAS染色观察杯状细胞数量及其分泌黏液功能,免疫组化染色法检测增殖细胞核抗原(PCNA)表达.[结果]与清肠栓低剂量组、SASP组、模型对照组和正常组比较,清肠栓高剂量组大鼠结肠黏膜炎症消除和溃疡愈合,杯状细胞数量及黏液增加,溃疡边缘腺体细胞增殖加强,PCNA表达增加(P＜0.05).[结论]清肠栓具有促进结肠炎大鼠结肠黏膜细胞增殖、增加杯状细胞的数量和分泌黏液的水平等作用,能够促进结肠溃疡愈合过程.     

Cyclo-oxygenase-2 inhibitors suppress epithelial cell kinetics and delay gastric wound healing in rats

BACKGROUND AND AIMS: The present study examined the effects of NS-398, a specific cyclo-oxygenase-2 inhibitor, on gastric mucosal cell kinetics and gastric wound healing following acid-induced injury. METHODS: Male Sprague-Dawley rats were fasted for 24 h and then 0.6 mol/L hydrochloric acid (HCl; 1 mL) was administered into the stomach; NS-398 or indomethacin was administered to the animals 10 min after the acid. Levels of constitutive cyclo-oxygenase (COX-1) and mitogen-inducible cyclo-oxygenase (COX-2) in the gastric mucosa were analysed using western blotting and immunohistochemical staining. The grade of the lesion was assessed using planimetry and histological examination, including immunohistochemistry for proliferating cell nuclear antigen (PCNA). RESULTS: Although there was strong expression of COX-1, there was minimal expression of COX-2 in the gastric mucosa. Expression of COX-2 was enhanced mainly in surface epithelial cells and neck cells following HCl administration. Gastric mucosal ulcers and erosions healed within 48 h, during which time the proliferative zone expanded in the control animals. Indomethacin and NS-398 suppressed the expansion of the proliferative zone and delayed the healing of the gastric injury. CONCLUSION: The present study demonstrated that cyclo-oxygenase-2 inhibitors delay gastric wound healing by suppressing expansion of the mucosal proliferative zone. These results provide evidence that cyclo-oxygenase-2 has an important role in gastric mucosal regeneration.     

Comparison of Indomethacin, Diclofenac and Aspirin-Induced Gastric Damage according to Age in Rats

Background/Aims

Aging gastric mucosa is known to have decreased mucosal defenses and increased susceptibility to injury by nonsteroidal anti-inflammatory drugs. Depending on the type of nonsteroidal anti-inflammatory drug (NSAID), the underlying mechanisms and the extent of damage to the stomach or intestine may differ. This study was performed to evaluate the acute gastric damage caused by different doses of indomethacin, diclofenac and aspirin in rats of various ages.

Methods

For the acute models, indomethacin (10, 20 or 40 mg/kg), diclofenac (40 or 80 mg/kg) or aspirin (100 mg/kg) was given to 7- and 25-week-old and 1-year-old Sprague-Dawley rats by intragastric gavage. The gross ulcer index, damage area as assessed by imaging, histological index, myeloperoxidase (MPO) activity, and cytosolic phospholipase A₂ (cPLA₂) levels were measured after 24 hours.

Results

The gross ulcer index and damage area increased with age in the presence of three NSAIDs (p<0.05). The increases in MPO levels induced by diclofenac and aspirin were significantly higher in 1-year-old than 7-week-old rats (p<0.05). cPLA₂ expression induced by indomethacin (10 and 40 mg/kg) was greater in the 1-year-old rats, compared with 7-week-old rats (p<0.05).

Conclusions

NSAID-induced acute gastric damage increased in a dose- and age-dependent manner.     

Indomethacin treatment during initial period of acetic acid-induced rat gastric ulcer healing promotes persistent polymorphonuclear cell-infiltration and increases future ulcer recurrence

The study was performed to examine whether indomethacin administered during the initial period of acetic acid-induced gastric ulcer healing affects future ulcer recurrence. Gastric ulcers were produced in rats by subserosal injection of acetic acid. Indomethacin (1 mg/kg/day, orally) administered either alone or concomitant with ornoprostil (50µg/kg/day, orally) was started on the fourth day and continued for 56 days. In rats whose ulcer healed at the 90th day after production of ulcer, endoscopy was done every 30 days to examine recurrence of ulcer. Gastric specimens were obtained 10, 30, 60, 90, and 240 days after ulcer production for histology, to quantitate the height of regenerated mucosa, thickness of fibrous tissue, degree of polymorphonuclear cell infiltration, and PAS-positive cells. Cumulative ulcer recurrence rate was significantly higher in rats initially treated with indomethacin than in controls. Increased polymorphonuclear cell infiltration was the major histologic abnormality persisting after cessation of indomethacin. Ornoprostil reversed these abnormalities caused by indomethacin. In conclusion, the administration of indomethacin during the initial period of the ulcer healing promoted persistent polymorphonuclear cell infiltration and increased ulcer recurrence rates, possibly via a prostaglandin-dependent mechanism.The work was supported by The Ministry of Education, Science and Culture of Grant-in-Aid for General Scientific Research 02454236 and by the DVA Medical Research Service.     

Pentoxifylline prevents indomethacin induced acute gastric mucosal damage in rats: role of tumour necrosis factor alpha.

Neutrophil adherence within the gastric microcirculation is thought to be a major step in the pathogenesis of gastric mucosal damage induced by indomethacin. Pentoxifylline, a methylxanthine derivative, prevents leukocyte adherence to vascular endothelium and protects organs from shock by reducing tumour necrosis factor alpha (TNF alpha) concentrations. Rats were treated with 20 mg/kg oral indomethacin, pretreated with vehicle or with four different doses of pentoxifylline intraperitoneally, and killed after three hours. The gross gastric mucosal injury, neutrophil margination into the gastric microcirculation, mucosal concentrations of 6-keto-prostaglandin F1 alpha (PGF1 alpha), and PGE2 and serum TNF alpha values were measured. Whether the pentoxifylline induced protection involved nitric oxide mediated pathways or gastric acid secretion was evaluated. The data indicate that pentoxifylline reduces indomethacin induced mucosal damage and neutrophil margination in a dose dependent manner without exerting any effect on gastric mucosal prostaglandin concentrations. The maximally effective dose (200 mg/kg) of pentoxifylline reduced gastric damage by 90% and slightly stimulated acid secretion. The effect of pentoxifylline was not affected by pretreatment with the nitric oxide inhibitor. Pentoxifylline prevented the indomethacin induced increase in TNF alpha concentrations in a dose dependent fashion. Serum TNF alpha values were 30.5 (7.0) IU/ml (mean (SEM)) in rats treated with indomethacin alone and 5.0 (2.5) IU/ml (p < 0.01) in rats treated with indomethacin plus 200 mg/kg pentoxifylline. Pentoxifylline, therefore, prevents the acute gastric mucosal damage and neutrophil margination induced by indomethacin and reduces indomethacin induced release of TNF alpha.     

Reduction of non-steroidal anti-inflammatory drug induced gastric injury and leucocyte endothelial adhesion by octreotide.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) induce gastric ulcers. AIMS: To assess whether the somatostatin analogue octreotide prevents NSAID induced mucosal gastrointestinal damage in both animals and humans. The effect of octreotide on neutrophil adhesion to the endothelium was also evaluated. METHODS: Male Sprague-Dawley rats were pretreated either with saline (0.3 ml subcutaneously) or octreotide (0.001-1 ng/kg subcutaneously). After 30 minutes gastric ulcers were induced by the intragastric application of NSAIDs (20 mg/kg indomethacin, 200 mg/kg aspirin, 200 mg/kg ibuprofen, or 50 mg/kg diclofenac). Four hours later the rats were killed and gastric mucosal lesions were assessed by computed planimetry. To determine whether octreotide could prevent indomethacin induced injury in humans, 20 healthy volunteers were evaluated in a double blind, placebo controlled study. RESULTS: Octreotide prevented NSAID induced gastric mucosal lesions (p < 0.05). The dose response curve was U shaped and the most effective dose was 0.1 ng/kg. Leucocyte adherence in submucosal venules of the stomach was evaluated by in vivo microscopy. Octreotide (0.1 ng/kg subcutaneously) prevented indomethacin (20 mg/kg intragastric) induced leucocyte adherence in gastric submucosal venules (p < 0.05). Healthy human volunteers received 50 mg indomethacin orally thrice a day concomitantly with either an identical placebo or 0.01 microgram, 0.1 microgram, or 1 microgram octreotide subcutaneously thrice a day for three days. Injury was assessed by endoscopy. There was a negative correlation between the octreotide dose and injury score (p < 0.03 for gastric injury, p < 0.001 for duodenal injury). CONCLUSIONS: Octreotide protects the stomach from NSAID induced gastric injury, probably via its ability to reduce NSAID induced neutrophilic adhesion to the microvasculature. Octreotide also ameliorated indomethacin induced gastric and duodenal injury in humans.     

Effects of free radical scavengers on indomethacin-induced aggravation of gastric ulcer in rats

Effects of treatment with free radical scavengers in the healing process of acetic acid-induced gastric ulcer on the ulcer aggravation induced by indomethacin were investigated. Gastric ulcers were produced on the anterior wall of the stomach of male Sprague-Dawley rats by submucosal injection of 20% acetic acid. To investigate the role of oxygen radicals, rats with gastric ulcer were treated with scavengers for six weeks and then treated with indomethacin (1 mg/kg/day). While superoxide dismutase (10,000 units/kg/day) did not affect the ulcer area after indomethacin treatment, allopurinol (50 mg/kg/day) slightly inhibited the increase in ulcer area. Dimethyl sulfoxide (1% solution,ad libitum) produced a significant decrease in size of the ulcer after indomethacin treatment. Increased lipid peroxides in the gastric mucosa after indomethacin treatment decreased significantly in the rats of the dimethyl sulfoxide and allopurinol groups. These results indicate that lipid peroxidation mediated by oxygen radicals plays an important role in the mechanism of ulcer aggravation induced by indomethacin.     

EP4 agonist alleviates indomethacin-induced gastric lesions and promotes chronic gastric ulcer healing

AIM: To investigate EP4-selective agonist effect on indomethacin-induced gastric lesions and on the spontaneous healing of chronic gastric ulcers. METHODS: In a mouse model of gastric bleeding with high dose of indomethacin (20 mg/kg), an EP4-selective agonist was administered orally. Stomach lesions and gastric mucous regeneration were monitored. In a mouse model of chronic gastric ulcer induced by acetic acid, EP4 agonist effect on the healing of chronic gastric ulcer was evaluated in the presence or absence of low dose indomethacin (3 mg/kg). In cultured human gastric mucous cells, EP4 agonist effect on indomethacininduced apoptosis was assessed by flow cytometry. RESULTS: The EP4-selective agonist reduced high dose indomethacin-induced acute hemorrhagic damage and promoted mucous epithelial regeneration. Low-dose indomethacin aggravated ulcer bleeding and inflammation, and delayed the healing of the established chronic gastric ulcer. The EP4 agonist, when applied locally, not only offset indomethacin-induced gastric bleeding and inflammation, but also accelerated ulcer healing. In the absence of indomethacin, the EP4 agonist even accelerated chronic gastric ulcer healing and suppressed inflammatory cell infiltration in the granulation tissue. In vitro , the EP4 agonist protected human gastric mucous cells from indomethacin-induced apoptosis. CONCLUSION: EP4-selective agonist may prevent indomethacin-induced gastric lesions and promote healing of existing and indomethacin-aggravated gastric ulcers, via promoting proliferation and survival of mucous epithelial cells.     

Study of 16,16-dimethyl prostaglandin E2 for prevention of stress ulcer after hepatectomy of experimental cirrhotic liver and its influence on hepatic regeneration

The influence of 16,16-dimethyl prostaglandin E2 (16,16-dm PGE2; an agent used for the prevention of stress ulcer after hepatectomy of the cirrhotic liver) on liver regeneration after hepatectomy was studied in rats. The following results were obtained. Ulceration after the stress of 6 h of water immersion was markedly suppressed in rats treated with 30 r/kg of 16,16-dmPGE2 as compared with the untreated controls. In animals that received hepatectomy alone, the gastric pH and gastric mucosal blood flow showed significant reduction from the preoperative levels. In animals that received hepatectomy plus 16,16-dmPGE2 treatment the postoperative reduction in the gastric pH and gastric mucosal blood flow was suppressed, suggesting the effectiveness of 16,16-dmPGE2 treatment in the prevention of stress ulcer after hepatectomy of the cirrhotic liver. The 3H-thymidine uptake percentage and thymidine activity 24 h after hepatectomy and the DNA content 30 h after hepatectomy were significantly higher in animals treated with 16,16-dmPGE2 than in the untreated controls. In animals that were treated intraperitoneally with 50 mg/kg of indomethacin 6 h before hepatectomy the mitotic index 30 h after hepatectomy was markedly lower than that in untreated controls. This indomethacin-induced reduction in the mitotic index tended to be normalized by treatment with 16,16-dmPGE2. These results suggest that 16,16-dmPGE2 treatment effectively prevents stress ulcer and favorably affects hepatic regeneration after hepatectomy of the cirrhotic liver.     

Plasticity of myofibroblasts appearing in granulation tissues after acetic acid treatment effect of bFGF

To clarify the origin of the myofibroblasts appearing in the healing process of the acetic acid-induced ulcer and effect of basic fibroblast growth factor (bFGF) on these myofibroblasts, we conducted an immunohistochemical study using antibody to intermediate filaments, desmin and vimentin. The binding sites of bFGF on the regenerative tissues were also studied by the radioautographic study of soluble compounds. As a result, the binding sites of bFGF were accumulated on the fibroblasts and myofibroblasts as well as on endothelial cells. The effect of CS23, acid-stable human recombinant bFGF was shown on distribution of myofibroblasts and regeneration of the microvascular system in the mucosal and submucosal layer.