Acid-induced Gastric Ulcers In Rats Research Articles

Effect of shikonin and its derivatives, pentaacetylated shikonin (MDS-004) on granuloma formation and delayed-type allergy in experimental animals

Of twelve reduced and acetylated derivatives of shikonin, a chemical constituent of Shikon, the accelerating activity on granuloma formation and the inhibitory activity on delayed-type allergy were investigated in order to find a compound having more characteristic effect than shikonin on wound healing in experimental animals. As a result, it was found that a reduced and pentaacetylated derivative of shikonin, MDS-004, has more excellent pharmacological activity. MDS-004 (0.1-1 mg/pellet) accelerated dose-dependently felt-pellet-induced granuloma formation when given topically together with felt-pellets in rats. It also produced strong inhibition against delayed-type allergies (ear edema) caused by oxazolone and dinitrofluorobenzene by topical application of up to 1 mg/ear to the ear skin of mice; its potency was far superior to that of shikonin. Orally administered MDS-004, unlike shikonin, inhibited carrageenan-induced hind paw edema, and exhibited tendency to heal acetic acid-induced gastric ulcer in rats. However, MDS-004, as well as commercial wound healing drugs tested and shikonin, did not show any healing action in the incised and open wound models in rats, if applied topically to the wound as 5 and 10% powders. On the other hand, MDS-004 did not produce irritative action on the ear skin at a topical dose of 1 mg/ear different from shikonin, and any behavioral changes after oral administration of 100 mg/kg in mice. These results suggest that a white powder MDS-004, different from deep purple shikonin, has accelerating action on granuloma formation without irritative action and stronger inhibitory action on delayed-type allergy by topical application than shikonin.

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.

Quality of gastric ulcer healing: histological and ultrastructural assessment

It has long been assumed that the mucosa in areas of grossly 'healed' gastric or duodenal ulcers returns to normal, either spontaneously or after treatment. This assumption is based almost entirely upon visual, superficial examination by endoscopy. Few, if any, histological and ultrastructural studies examined the deeper mucosa in the areas of grossly healed ulcers. In several experimental studies, we analysed the development, evolution, and healing of acetic acid-induced gastric ulcers in rats and assessed the histological and ultrastructural features (structure and cellular composition) of the gastric mucosa in areas of grossly healed ulcers. The gastric mucosa of grossly 'healed' ulcers showed re-epithelialization of the mucosal surface at every study interval (2 weeks, 2, 3, and 4 months), but the subepithelial mucosa displayed prominent abnormalities. Two patterns of scarring were distinguished: (a) the mucosa in the area of healed ulcer was thinner (25-45% thinner than normal mucosa) with increased connective tissue and poor differentiation and/or degenerative changes in the glandular cells; and (b) the mucosa displayed a marked dilation of gastric glands with poor differentiation of the glandular cells and a reduction in the supportive microvascular network. It is theorized that these abnormalities could interfere with oxygenation, nutrient supply, and mucosal resistance and defence; therefore, they could be a basis for ulcer recurrence. These observations indicate that the quality of mucosal structural restoration rather than the speed of ulcer healing is the most important factor in determining risk of ulcer recurrence. The clinical relevance of these findings is supported by a preliminary study in which marked histological abnormalities were found in the subepithelial mucosa in patients with 'healed' duodenal ulcers.

P-563 - Effects of 5-HT, bradykinin, PGF1α, and histamine on the contractility of connective tissue isolated from the base of acetic acid-induced gastric ulcers in rats.

P-563 - Effects of 5-HT, bradykinin, PGF1α, and histamine on the contractility of connective tissue isolated from the base of acetic acid-induced gastric ulcers in rats.

Evaluation of Acetic Acid-Induced Gastric Ulcers in Rats by Scanning Acoustic Microscopy

To clarify the mechanism of gastric ulcer recurrence, we studied acetic acid-induced gastric ulcers. The healing of these gastric ulcers was then studied for 4-21 weeks after the injection. Forty-eight ulcers were examined by macroscopic observation and scanning acoustic microscopy (SAM) and by histologic study of the ulcers. SAM has a higher radio frequency and provides more detailed information about the gastric wall than endoscopic ultrasonography (EUS). Thirteen healed and 35 non-healed gastric ulcers were observed by macroscopic observation over 4-21 weeks. SAM enabled us to observe the normal gastric wall of the rat in five different layers. The SAM echo patterns of the healed ulcers were all one pattern. On the other hand, we were able to classify the echo patterns of the non-healed ulcers into two different patterns; one pattern consisted of a high-echogenic region in the first and second layers with an underlying relatively high echogenic region in a horizontal pattern. The other pattern showed a poorly defined and spotted low-echogenic region in the first and second layers which fanned out toward the fifth layer. However, these two different ulcers could not be distinguished macroscopically. Histologic findings supported the results of the SAM study which showed one pattern in healed ulcers and two patterns in non-healed ulcers. In the non-healed ulcers the two different patterns may be ascribed to the proliferation of collagen fibers. SAM makes it possible to image the proliferation of collagen fibers and identify the two different types with an accuracy of 97%.(ABSTRACT TRUNCATED AT 250 WORDS)

Healing of acetic acid-induced gastric ulcer and gastric mucosal PGI2 level in rats

The present study was designed to investigate the changes in gastric mucosal PGI2 level accompanying the healing of acetic acid-induced gastric ulcers in rats. The ulcers, which were observed with an endoscope, were found to undergo periods of decrease, healing and exacerbation during the rat's lifetime. The phases were categorized as follows: (1) the reduction period (days 3-50 after ulcer induction, corresponding to 7-14 weeks of age), (2) healing period (days 35-150 after ulcer induction, corresponding to 12-29 weeks of age), (3) first exacerbation period (days 35-231 after ulcer induction, corresponding to 12-40 weeks of age), (4) inactive period (days 231-365 after ulcer induction, corresponding to 40-60 weeks of age), and (5) second exacerbation period (days 365-550 after ulcer induction, corresponding to 60-86 weeks of age). In normal rats, the level of gastric mucosal PGI2 gradually increased with aging between 7 and 20 weeks, then decreased up to 40 weeks. The PGI2 level in the 60-week-old rat did not differ from that in the 40-week-old rat. The PGI2 level was the lowest in the 86-week-old rat. In ulcer-bearing rats, the PGI2 level showed the same pattern of change as that in normal rats, but the level was higher. The above results indicated a marked decrease in PGI2 level between 20 and 40 weeks of age and between 60 and 86 weeks of age in normal and ulcer-bearing rats. These periods corresponded closely to the first and second exacerbation periods, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Orally Administered Human Epidermal Growth Factor on Natural and Delayed Healing of Acetic Acid-Induced Gastric Ulcers in Rats

We examined the effects of orally administered human epidermal growth factor (hEGF) on healing of acetic acid-induced gastric ulcers in rats. hEGF, given twice daily at 30 and 100 μg/kg for 2 weeks or at 100 μg/kg for 4 weeks to rats with ulcers, had no effect on natural healing or the gastric secretion, delayed one caused by indomethacin. Oral hEGF had no effect on basal histamine-stimulated gastric secretion, and stomach weight. These results indicate that oral hEGF has no biological activity on the pathophysiology of the stomach.

Vascular and Microvascular Changes—Key Factors in the Development of Acetic Acid-Induced Gastric Ulcers in Rats

The present study examined the time sequence and histologic and ultrastructural features of the formation and evolution of experimental, acetic acid-induced gastric ulcerations in rats. One hundred percent acetic acid was applied to the gastric serosa of 140 fasted male Sprague-Dawley rats through a polyethylene tube for 30 s. Gastric mucosal changes were evaluated at 1, 5, 15, and 30 min, 1 and 3 h, and 1, 2, 3, 5, 8, and 11 days after acetic acid application by visual inspection, by quantitative and qualitative light microscopy, and by transmission electron microscopy. Following exposure to acetic acid, the earliest morphologic changes occurred at 1 min and consisted of dilatation of large submucosal veins and arteries and mucosal collecting venules. Five to 15 minutes after injury, thrombi developed in submucosal veins and collecting venules, leading to microvascular stasis and mucosal necrosis. By 3 h, necrotic masses started to detach. By 24-48 h, necrotic changes penetrated the submucosa. By 72 h, most ulcers underwent transition into a "chronic" stage characterized histologically by the presence of granulation tissue at the bottom, and the appearance of a transitional healing zone at the margins. By 5 days, an increased amount of granulation tissue was observed and the gastric glands in transitional zones at the ulcer margin displayed cystic dilatation. Based on this study, we conclude that a key feature of acetic acid-induced ulcer formation is the early vascular and microvascular injury, which precedes glandular cell necrosis.

Effects of orally administered human epidermal growth factor on natural and delayed healing of acetic acid-induced gastric ulcers in rats.

We examined the effects of orally administered human epidermal growth factor (hEGF) on healing of acetic acid-induced gastric ulcers in rats. hEGF, given twice daily at 30 and 100 micrograms/kg for 2 weeks or at 100 micrograms/kg for 4 weeks to rats with ulcers, had no effect on natural healing or the gastric secretion, delayed one caused by indomethacin. Oral hEGF had no effect on basal histamine-stimulated gastric secretion, and stomach weight. These results indicate that oral hEGF has no biological activity on the pathophysiology of the stomach.

O-194 - Removal of granulation tissue from the bottom of acetic acid-induced gastric ulcers in rats

O-194 - Removal of granulation tissue from the bottom of acetic acid-induced gastric ulcers in rats

酢酸潰ようの治癒過程における胃粘膜アミン含量および関連酵素活性に対する抗潰よう薬の影響

In order to elucidate the action of an H2 blocker (cimetidine) and gastric mucosal protection agents (sucralfate and sofalcone) on the relapse and recurrence of gastric ulcer, the effects of cimetidine, sucralfate and sofalcone on the contents of histamine and serotonin and histidine decarboxylase (HDC) activity in the gastric mucosa were examined in the ulcer region and the intact region at the 10th day after the operation to produce acetic acid-induced gastric ulcer in rats. The following results were obtained: 1) HDC activity in the gastric mucosa of rats treated with cimetidine (100 mg/kg twice daily) tended to increase in the intact region, and it was significantly increased in the ulcer region. 2) Increased HDC activity due to cimetidine treatment was observed at the 10th day after interruption of cimetidine administration. 3) The HDC activity in the gastric mucosa was not changed by the treatment with sucralfate (500 mg/kg/day) and sofalcone (200 mg/kg/day). The results suggest that the increased HDC activity in the gastric mucosa might participate in the relapse and recurrence of gastric ulcer after discontinuation of cimetidine administration.

Effects of Cimetidine and Omeprazole on Angiogenesis in Granulation Tissue of Acetic Acid-Induced Gastric Ulcers in Rats

We investigated the effects of cimetidine and omeprazole on angiogenesis in granulation tissue and on the healing of gastric ulcers induced by acetic acid in rats. Either cimetidine (50 or 100 mg/kg) or omeprazole (10 or 20 mg/kg) was orally administered once daily for 9 consecutive days from the day following ulcer production. The ulcer index on the 10th and 30th days after ulcer production, and the extent of angiogenesis on the 10th day were examined. Cimetidine dose-dependently decreased the extent of angiogenesis on the 10th day, whereas the ulcer index on the 10th days was not significantly different between cimetidine-treated and control rats. The ulcer index of the groups treated with cimetidine during the initial 9-day period was increased compared with the control group on the 30th day. In contrast, oral omeprazole did not affect angiogenesis on the 10th day and decreased the ulcer index on both the 10th and 30th days. These results suggest that oral cimetidine may inhibit angiogenesis in ulcer granulation tissue possibly via the blocking of histamine H2 receptors and this may be one cause of delayed ulcer healing.

新しいＨｉｓｔａｍｉｎｅ Ｈ２‐受容体きっ抗薬，ＩＴ‐０６６，のラットおよびイヌの胃液分泌および酢酸潰ように対する効果

We examined the effects of a new histamine H2-receptor antagonist, 3-amino-4-(4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis-2- butenylamino)-3- cyclobutene-1,2-dione hydrochloride (IT-066), on gastric acid secretion and the healing process of experimental ulcers in rats and dogs. Famotidine, a well-established H2-receptor antagonist, was used as the reference drug. Male Donryu rats (240-260 g) and Beagle dogs of both sexes (8-10 kg), having Heidenhain pouches, were used. IT-066 dose-dependently inhibited the basal gastric acid secretion of rats, and this inhibition significantly persisted for 12 hr. In addition, the agent significantly inhibited histamine-stimulated acid secretion in both normal rats and rats with acetic acid ulcers. IT-066, given p.o. twice daily for 2 and 3 weeks after ulceration, significantly accelerated both spontaneous and delayed healing (with indomethacin) of acetic acid-induced gastric ulcers in rats. The effects of IT-066 on acid secretion and ulcer healing were almost the same or slightly more potent than those observed with famotidine. IT-066, when given i.v. or p.o., dose-dependently inhibited the gastric acid secretion stimulated by histamine, pentagastrin, or carbachol in dogs. The antisecretory effects of the agent on histamine-stimulated acid secretion significantly persisted for more than 6 hr. These results indicate that IT-066 appears to be a promising antisecretory and anti-ulcer agent.

Effect of Omeprazole on Delayed Healing of Acetic Acid-Induced Gastric Ulcers in Rats

Omeprazole, a gastric mucosal proton pump inhibitor, significantly and dose-dependently prevented the delayed healing of acetic acid-induced gastric ulcers in response to repeatedly administered indomethacin to rats. Both basal and histamine-stimulated gastric acid secretions in rats with acetic acid-induced ulcers that were given indomethacin were markedly and persistently (>24 hr) inhibited after 4 weeks treatment with omeprazole. The prevention of delayed ulcer healing by omeprazole appears to be due to its long-lasting antisecretory activity.

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.

Relapse of acetic acid-induced gastric ulcer and gastric mucosal prostaglandin I2 level in rats.

The healing process of acetic acid-induced gastric ulcer in rats was observed with an endoscope for 365 d after ulcer induction. The ulcers were induced by acetic acid solutions of various concentrations (2.5 (I), 5.0 (II), 10 (III) and 20% (IV); 0.05 ml). On day 3, a positive correlation was observed between the ulcer index (UI) and the concentration of acetic acid solution. On day 365, cumulative healing rates in groups I, II, III and IV amounted to 100, 100, 58.3 and 51.7%, respectively. The cumulative relapse rates in groups I, II, III and IV were 0, 13.6, 66.7 and 58.6%, respectively. Significant correlations were observed between initial UI values and cumulative healing or cumulative relapse rate. On day 365, rats were divided into two groups, a healed group and non-healed group, and the gastric mucosal prostaglandin I2 (PGI2) level was measured by bioassay. The PGI2 level around ulcers in ulcer-induced rats was higher than in normal rats, and it was higher in non-healed rats than in healed rats. Moreover, the PGI2 level was higher in those groups which showed a higher cumulative relapse rates. The above results indicated that the initial ulcer size and the PGI2 level around the ulcer might correlate to ulcer healing or exacerbation.

Physiological Significance of Mucous Neck Cell-type Mucins in the Healing of Acetic Acid-induced Gastric Ulcers in Rats

The present study was undertaken to elucidate the role of mucous secreting cells in the healing of acetic acid-induced gastric ulcers in rats. The results indicated that mucous neck cells (MNCs) and their secretions seem to play important roles in the prevention of the expansion of ulceration in the early stage. The reasons are that the surface mucous layer coating the ulcerated surface almost exclusively consists of MNC-type mucins and MNCs increase markedly in the mucosae surrounding ulcers. Transitional type cells containing both MNC-type and chief cell-type granules frequently occurred in this region, although chief cells almost completely disappeared.

Role of the Mucus Gel Layer in the Healing of Acetic Acid-induced Gastric Ulcers in Rats

Changes in the pH gradient and thickness of the mucus gel layer in the healing of acetic acid-induced gastric ulcers in rats were investigated. The maximum of the pH gradient and the thickness of mucus gel layer at the edge of ulcers and in the regenerated mucosa were higher, decreased gradually with the healing of the ulcers and finally reached normal values. This indicates that mucus and bicarbonate are secreted actively from the mucosa surrounding an ulcer and that they play an important role in protection of the base of ulcers and in acceleration of the healing of the ulcers.